'61 Front End Alignment Question - Caster
07-13-2009, 10:18 AM
#1
Le Mans Master
Thread Starter
'61 Front End Alignment Question - Caster
After replacing the third arm bearing and tie rod ends and rebuilding the steering box I had the front end aligned at a local shop that's been around for a long time. I took in the specs I got off the old posts here on the Forum that effectively said the specs from the ST-12 were good to use other than maybe reducing the toe-in due to using radial tires.
Most of the 150 miles put on the car have only been around town and not much on the highway. The car tracks fine with no wander but yesterday coming off the freeway on a sweeping curve, the car felt like the steering ratio quickened up a bit. I know that sounds odd but let's just say the little extra steering wheel input about half way into the turn resulted in the car feeling like it was darting to the inside more than I would have expected.
Now, back when it was aligned, I had explained that the camber caster adjustment was behind the grease fitting and when he was done he told me that there seemed to be a bit of a tradeoff meaning he wasn't able to get both Camber and Caster to fit within the specs.
Here are the numbers after being aligned:
Camber Left: -0.2 Camber Right: 0.2
Caster Left: 0.5 Caster Right: 0.7
Toe Left: 0.02 Toe Right: 0.04
Is the lack of the Caster being in the 2 degree range the cause of the squirreliness I'm seeing? And if so, since the same adjustment is responsible for both Camber and Caster, is there a way to bring the Caster up without screwing up the Camber setting?
By the way, all the rest of the suspension is in good shape.
Also, I've read that the 'rake' of the vehicle might effect the alignment but in this case, the rear tires are 27.1 inches tall and the fronts 26.9 although there are air shocks in the back that kick up the rear end less than a 1/4-inch.
Thanks,
Mike T.
Most of the 150 miles put on the car have only been around town and not much on the highway. The car tracks fine with no wander but yesterday coming off the freeway on a sweeping curve, the car felt like the steering ratio quickened up a bit. I know that sounds odd but let's just say the little extra steering wheel input about half way into the turn resulted in the car feeling like it was darting to the inside more than I would have expected.
Now, back when it was aligned, I had explained that the camber caster adjustment was behind the grease fitting and when he was done he told me that there seemed to be a bit of a tradeoff meaning he wasn't able to get both Camber and Caster to fit within the specs.
Here are the numbers after being aligned:
Camber Left: -0.2 Camber Right: 0.2
Caster Left: 0.5 Caster Right: 0.7
Toe Left: 0.02 Toe Right: 0.04
Is the lack of the Caster being in the 2 degree range the cause of the squirreliness I'm seeing? And if so, since the same adjustment is responsible for both Camber and Caster, is there a way to bring the Caster up without screwing up the Camber setting?
By the way, all the rest of the suspension is in good shape.
Also, I've read that the 'rake' of the vehicle might effect the alignment but in this case, the rear tires are 27.1 inches tall and the fronts 26.9 although there are air shocks in the back that kick up the rear end less than a 1/4-inch.
Thanks,
Mike T.
Last edited by Vet65te; 07-13-2009 at 10:23 AM. Reason: Added Rake Info
07-13-2009, 11:16 AM
#2
Melting Slicks
That's not much caster...
I'm running 2.7*, but have power steering so it can handle it. Tracks very well!
I wonder if the tech understood that he needed to keep turning the pivot pin until he got 2* caster FIRST, and then dial in the camber with less than one turn? Think of caster as "coarse adjust" and camber as "fine adjust" on this set-up.
As you turn it to get the right caster angle, the camber is moving in and out because of the eccentric on the shaft.
Make sure he tightened the clamp bolts...
I wonder if the tech understood that he needed to keep turning the pivot pin until he got 2* caster FIRST, and then dial in the camber with less than one turn? Think of caster as "coarse adjust" and camber as "fine adjust" on this set-up.
As you turn it to get the right caster angle, the camber is moving in and out because of the eccentric on the shaft.
Make sure he tightened the clamp bolts...
07-13-2009, 12:18 PM
#3
Drifting
After replacing the third arm bearing and tie rod ends and rebuilding the steering box I had the front end aligned at a local shop that's been around for a long time. I took in the specs I got off the old posts here on the Forum that effectively said the specs from the ST-12 were good to use other than maybe reducing the toe-in due to using radial tires.
Most of the 150 miles put on the car have only been around town and not much on the highway. The car tracks fine with no wander but yesterday coming off the freeway on a sweeping curve, the car felt like the steering ratio quickened up a bit. I know that sounds odd but let's just say the little extra steering wheel input about half way into the turn resulted in the car feeling like it was darting to the inside more than I would have expected.
Most of the 150 miles put on the car have only been around town and not much on the highway. The car tracks fine with no wander but yesterday coming off the freeway on a sweeping curve, the car felt like the steering ratio quickened up a bit. I know that sounds odd but let's just say the little extra steering wheel input about half way into the turn resulted in the car feeling like it was darting to the inside more than I would have expected.
Now, back when it was aligned, I had explained that the camber caster adjustment was behind the grease fitting and when he was done he told me that there seemed to be a bit of a tradeoff meaning he wasn't able to get both Camber and Caster to fit within the specs.
Here are the numbers after being aligned:
Camber Left: -0.2 Camber Right: 0.2
Caster Left: 0.5 Caster Right: 0.7
Toe Left: 0.02 Toe Right: 0.04
Is the lack of the Caster being in the 2 degree range the cause of the squirreliness I'm seeing? And if so, since the same adjustment is responsible for both Camber and Caster, is there a way to bring the Caster up without screwing up the Camber setting?
By the way, all the rest of the suspension is in good shape.
Also, I've read that the 'rake' of the vehicle might effect the alignment but in this case, the rear tires are 27.1 inches tall and the fronts 26.9 although there are air shocks in the back that kick up the rear end less than a 1/4-inch.
Thanks,
Mike T.
Here are the numbers after being aligned:
Camber Left: -0.2 Camber Right: 0.2
Caster Left: 0.5 Caster Right: 0.7
Toe Left: 0.02 Toe Right: 0.04
Is the lack of the Caster being in the 2 degree range the cause of the squirreliness I'm seeing? And if so, since the same adjustment is responsible for both Camber and Caster, is there a way to bring the Caster up without screwing up the Camber setting?
By the way, all the rest of the suspension is in good shape.
Also, I've read that the 'rake' of the vehicle might effect the alignment but in this case, the rear tires are 27.1 inches tall and the fronts 26.9 although there are air shocks in the back that kick up the rear end less than a 1/4-inch.
Thanks,
Mike T.
07-13-2009, 12:18 PM
#4
Race Director
Take a look at the top A arm and see if the spindle support is tight up against the A arm at the rear. if it is, you are maxed out on caster unless you add second set of 2 degrees shims between the front cross member and frame.
If it isn't bottomed out, but some larger amount (say .1", your alignment guy can dial some more caster in, though the camber will go way negative on it way to being positive again.
I would make sure everything was tightened back up. The last , and I mean last, alignment guy I had work on my car didn't tighten the tie rod ends. I bought my own alignment gauge and did it myself.
I also determined one of my spindle supports is slightly bent and I can't get camber to full spec, so next time I am bored, or need to change kingpins, I will replace that spindle support
Doug
07-13-2009, 12:41 PM
#5
Safety Car
Mike,
I would doubt that what you are feeling is coming from the front end as well. Lack of caster will cause a little twitchiness in the steering and will cause the car to wander at higher speeds, but it sure sounds like this might be coming from the rear end, or even the tires.
That being said, they should be able to get more caster into the front suspension than that! That is why they put the tapered aluminum shims in between the frame and front crossmember, to add more caster.
I would guess that he was unaware that the caster adjustment can be adjusted several turns. The camber changes through it's entire range on each rotation of the screw, so the process is to adjust the screw for caster, and then slightly move the screw to bring the camber in line.
I like running high caster for the high speed stability it brings, but it does increase steering effort as the caster increases.
I am glad to see that you have the car on the road and are driving it!
Ken's 58 is getting close, and he should be driving it by fall. I have posted some pics of it in another post.
Regards, John McGraw
I would doubt that what you are feeling is coming from the front end as well. Lack of caster will cause a little twitchiness in the steering and will cause the car to wander at higher speeds, but it sure sounds like this might be coming from the rear end, or even the tires.
That being said, they should be able to get more caster into the front suspension than that! That is why they put the tapered aluminum shims in between the frame and front crossmember, to add more caster.
I would guess that he was unaware that the caster adjustment can be adjusted several turns. The camber changes through it's entire range on each rotation of the screw, so the process is to adjust the screw for caster, and then slightly move the screw to bring the camber in line.
I like running high caster for the high speed stability it brings, but it does increase steering effort as the caster increases.
I am glad to see that you have the car on the road and are driving it!
Ken's 58 is getting close, and he should be driving it by fall. I have posted some pics of it in another post.
Regards, John McGraw
07-13-2009, 12:54 PM
#6
Melting Slicks
I had a similar thing with mine and it turned out the tie rod on one side wasn't tightned, same as AZDoug. As mentioned earlier they might not have realized about the caster adjustment.
07-13-2009, 01:32 PM
#7
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I was going to mention what Mike just mentioned------------make sure the clamp bolt at the top of the spindle support (upright) was tightened!!!
Also, and you probably already know this, as the eccentric bolt is turned, and because it's on an angle, BOTH caster/camber are changed. This sometimes makes it difficult to achieve the desired setting, because as the eccentric is turned, it moves forward/backward. Sometimes to achieve the desired caster or camber, the bolt must be moved so far that the other can't be achieved.
The frontend/alignment shop that I use (the guy has been in business since the Civil War days
) showed me something that I had never seen before. If the upper-outer eccentric bolt must be turned an excessive amount, then they loosen the bolts which attaches the lower-inner A-frame cross shaft to the cross member. The cross shaft is then GENTLY pryed away from the cross member and shims installed between the shaft and cross member (either front or rear of shaft as needed), then the bolts are tightened back up. This will increase/decrease caster (depending on which end of the shaft gets shimmed), thus providing additional adjustment of the upper-outer shaft for needed camber adjustment.
Some of you are possibly aware of another adjustment method which can be done which involves bending (YES, I said bending) the spindle support. The bending is done in the area of the support between the knuckle for the kingpin and the upper end of the support. Today, there are probably VERY FEW alignment shops who have either the equipment or the skills to do such bending. You DO NOT want to be present when this is performed on your prized 53-62 Corvette, or, your 49-54 Chevy (same frontend) because it's SCARY AS HELL TO SEE THEM DO IT!!!!!!!!!!!!!!!!!
Hopefully the alignment can be satisfactorily accomplished WITHOUT bending, but it is (or used to be many years ago) a method that alignment shops once use quite successfully----------------------BY A SKILLED, PROPERLY TRAINED ALIGNMENT PERSON! Most of those guys are either gone
or retired today! 
Tom Parsons
Also, and you probably already know this, as the eccentric bolt is turned, and because it's on an angle, BOTH caster/camber are changed. This sometimes makes it difficult to achieve the desired setting, because as the eccentric is turned, it moves forward/backward. Sometimes to achieve the desired caster or camber, the bolt must be moved so far that the other can't be achieved.
The frontend/alignment shop that I use (the guy has been in business since the Civil War days
) showed me something that I had never seen before. If the upper-outer eccentric bolt must be turned an excessive amount, then they loosen the bolts which attaches the lower-inner A-frame cross shaft to the cross member. The cross shaft is then GENTLY pryed away from the cross member and shims installed between the shaft and cross member (either front or rear of shaft as needed), then the bolts are tightened back up. This will increase/decrease caster (depending on which end of the shaft gets shimmed), thus providing additional adjustment of the upper-outer shaft for needed camber adjustment.Some of you are possibly aware of another adjustment method which can be done which involves bending (YES, I said bending) the spindle support. The bending is done in the area of the support between the knuckle for the kingpin and the upper end of the support. Today, there are probably VERY FEW alignment shops who have either the equipment or the skills to do such bending. You DO NOT want to be present when this is performed on your prized 53-62 Corvette, or, your 49-54 Chevy (same frontend) because it's SCARY AS HELL TO SEE THEM DO IT!!!!!!!!!!!!!!!!!
Hopefully the alignment can be satisfactorily accomplished WITHOUT bending, but it is (or used to be many years ago) a method that alignment shops once use quite successfully----------------------BY A SKILLED, PROPERLY TRAINED ALIGNMENT PERSON! Most of those guys are either gone
or retired today! Tom Parsons
07-13-2009, 03:01 PM
#8
Le Mans Master
Thread Starter
Great input, guys. I looked at the upper spindle support location and the drivers side does appear to be more towards the rear while the passenger side is about dead center. I also made a not-so-great discovery when looking at the upper A-arm on the drivers side, that upper/inner shaft was tackwelded to the A-arm. I assume the hex fitting at the end of the shaft is a press fit into the upper A-arm so this shouldn't be a real bad thing...unless I want to take the front suspension apart at some point?
So, let me see if I understand this lack of caster situation correctly. At around 60mph the car seems to track well enough and doesn't feel twitchy (make that 'anymore' twitchy than it already is) with the small amount of caster I have in the front end now but adding more caster will make it track even better but with the tradeoff of increasing the steering resistance? I might be tempted to not add in the caster if it adds to the steering effort needed.
Other details on the front end suspension setup on my 61 are that the coil springs are shorter than stock which I like for the 'looks'. I measured them at about 12 3/4 free height and after contacting a few vendors found the stock replacements to be in the 13 3/4 free height range so they are about an inch shorter than stock.
The old 90/10 drag shocks were shot and replaced with NAPA/Monroe Sensa Tracs. Old petrified front sway bar bushings replaced with new.
I hadn't thought about the rear suspension contributing to this squirreliness up front so let me fill in the blanks as to what I have on this '61. The stock rear springs were replaced with 5-leaf springs a number of years ago and the perch bushings appear to be in good shape. It did have the upper radius rods and the bushings were shot on them so I removed them entirely in an effort to soften the rear suspension reaction because I also have a variation of the Traction Masters underneath and the consensus was that the rear was almost 'locked up' having the upper radius rods 'and' the lower Traction Master device (pics attached). Removing the radius rods has helped although in a small way.
Rear sway bar bushings are crusty looking but substantial enough to still work well enough I believe.
The car does have rear air shocks and I suppose there's a chance (albeit a slim chance) they might be contributing to the oversteer up front in that there's only one fill valve. I had read (a very long time ago) that when a pair of air shocks are using the same pressure line that, in a turn, the outside shock could compress and effectively pump the air over into the opposite shock causing that inside shock to extend thereby adding to the body lean. Sounds plausible but probably not the main reason for the squirreliness.
As for the tires, they are far from fresh. The front 215-70's are dated '92 and the rear 255-60's are dated '93. No 'external' deterioration to be seen but all 4 will be replaced...just as soon as I figure out which spoked American I will be running so I can do them all at one time.
Mike T.
So, let me see if I understand this lack of caster situation correctly. At around 60mph the car seems to track well enough and doesn't feel twitchy (make that 'anymore' twitchy than it already is) with the small amount of caster I have in the front end now but adding more caster will make it track even better but with the tradeoff of increasing the steering resistance? I might be tempted to not add in the caster if it adds to the steering effort needed.
Other details on the front end suspension setup on my 61 are that the coil springs are shorter than stock which I like for the 'looks'. I measured them at about 12 3/4 free height and after contacting a few vendors found the stock replacements to be in the 13 3/4 free height range so they are about an inch shorter than stock.
The old 90/10 drag shocks were shot and replaced with NAPA/Monroe Sensa Tracs. Old petrified front sway bar bushings replaced with new.
I hadn't thought about the rear suspension contributing to this squirreliness up front so let me fill in the blanks as to what I have on this '61. The stock rear springs were replaced with 5-leaf springs a number of years ago and the perch bushings appear to be in good shape. It did have the upper radius rods and the bushings were shot on them so I removed them entirely in an effort to soften the rear suspension reaction because I also have a variation of the Traction Masters underneath and the consensus was that the rear was almost 'locked up' having the upper radius rods 'and' the lower Traction Master device (pics attached). Removing the radius rods has helped although in a small way.
Rear sway bar bushings are crusty looking but substantial enough to still work well enough I believe.
The car does have rear air shocks and I suppose there's a chance (albeit a slim chance) they might be contributing to the oversteer up front in that there's only one fill valve. I had read (a very long time ago) that when a pair of air shocks are using the same pressure line that, in a turn, the outside shock could compress and effectively pump the air over into the opposite shock causing that inside shock to extend thereby adding to the body lean. Sounds plausible but probably not the main reason for the squirreliness.
As for the tires, they are far from fresh. The front 215-70's are dated '92 and the rear 255-60's are dated '93. No 'external' deterioration to be seen but all 4 will be replaced...just as soon as I figure out which spoked American I will be running so I can do them all at one time.
Mike T.
Last edited by Vet65te; 07-13-2009 at 03:12 PM. Reason: Added details on front end suspension parts.
07-13-2009, 03:43 PM
#9
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Mike,
I also have Traction Masters & 5 leaf rear springs, and I recently removed the rear anti-sway bar to remove the oversteer feel during sweeping turns (especially diminishing radius turns). You may want to do the same.
I have great front end alignment, but then again I do my own. The front stability is great with no wander or looseness whatsoever.
I also would increase caster from what you currently have (in to the 2 range).
Plasticman
I also have Traction Masters & 5 leaf rear springs, and I recently removed the rear anti-sway bar to remove the oversteer feel during sweeping turns (especially diminishing radius turns). You may want to do the same.
I have great front end alignment, but then again I do my own.
The front stability is great with no wander or looseness whatsoever. I also would increase caster from what you currently have (in to the 2 range).
Plasticman
Last edited by Plasticman; 07-13-2009 at 03:45 PM.
07-13-2009, 03:54 PM
#10
Le Mans Master
Thread Starter
Hey Plasticman, I now remember you mentioning the removal of the rear sway bar on another thread, when Traction Masters were in place. Was it a noticeable difference afterwards?
I used to think that adding rear sway bars to cars like the A-Body GM line, (GTO's, Chevelles, etc) made the front end plow a bit but maybe the solid axle Vettes react differently.
So, the Caster Adjustment get's set 'first' and then the Camber Adjustment and that the number of revolutions needed to get to the 'middle setting' of 2-degrees might be more than one and then the Camber Adjustment will only take less than one turn from that point?
I want to make sure I have the details well understood before I go back to the shop that did the alignment.
Mike T.
I used to think that adding rear sway bars to cars like the A-Body GM line, (GTO's, Chevelles, etc) made the front end plow a bit but maybe the solid axle Vettes react differently.
So, the Caster Adjustment get's set 'first' and then the Camber Adjustment and that the number of revolutions needed to get to the 'middle setting' of 2-degrees might be more than one and then the Camber Adjustment will only take less than one turn from that point?
I want to make sure I have the details well understood before I go back to the shop that did the alignment.
Mike T.
Last edited by Vet65te; 07-13-2009 at 04:01 PM.
07-13-2009, 04:12 PM
#11
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Hey Plasticman, I now remember you mentioning the removal of the rear sway bar on another thread, when Traction Masters were in place. Was it a noticeable difference afterwards?
I used to think that adding rear sway bars to cars like the A-Body GM line, (GTO's, Chevelles, etc) made the front end plow a bit but maybe the solid axle Vettes react differently.
So, the Caster Adjustment get's set 'first' and then the Camber Adjustment and that the number of revolutions needed to get to the 'middle setting' of 2-degrees might be more than one and then the Camber Adjustment will only take less than one turn from that point?
I want to make sure I have the details well understood before I go back to the shop that did the alignment.
Mike T.
I used to think that adding rear sway bars to cars like the A-Body GM line, (GTO's, Chevelles, etc) made the front end plow a bit but maybe the solid axle Vettes react differently.
So, the Caster Adjustment get's set 'first' and then the Camber Adjustment and that the number of revolutions needed to get to the 'middle setting' of 2-degrees might be more than one and then the Camber Adjustment will only take less than one turn from that point?
I want to make sure I have the details well understood before I go back to the shop that did the alignment.
Mike T.
Yes, removing the rear anti-sway bar made a positive change in getting rid of the oversteer.
"So, the Caster Adjustment get's set 'first' and then the Camber Adjustment and that the number of revolutions needed to get to the 'middle setting' of 2-degrees might be more than one and then the Camber Adjustment will only take less than one turn from that point?"
This is correct! You may find that you cannot reach the spec setting, but anything closer to 2 degrees will help.
Further info, my camber is set at zero for both sides, and my total toe-in is .100" (previously I had it set at .090" and frankly don't see any difference - .010" difference being rather nitpicking).
My specs for radial tires is:
Toe in (total) .090" to .125"
Camber 0 degrees +/- 1/4 deg.
Caster +2 degrees +/- 1/2 deg. (same as factory spec)
For Bias ply tires (factory specs):
Toe in (total) .125" to .250"
Camber +1/2 degree +/- 1/2 deg.
Caster +2 degrees +/- 1/2 deg.
Plasticman
Last edited by Plasticman; 07-13-2009 at 04:26 PM.
07-13-2009, 04:44 PM
#12
Le Mans Master
Thread Starter
Okay, now I've got the picture. I'll stop by the Tire Shop tomorrow morning when they open at 7AM and chat with Peter the guy who does the alignment. After looking for the 'relative location' of the upper/outer spindle clamp on the upper a-arm (per AZDoug's suggestion) and seeing that both spindles were near the middle (maybe the drivers side did appear to be a bit further to the rear) I'm guessing that there might be some more room for adjustment to get the Caster nearer to the magic 2-degree setting.
This shop is only open Tues through Friday and is alwasy busy so tomorrow will only cover the face-to-face discussion about the Caster settings and a followup appointment will have to be made for another day.
I like to make one change at a time so I'll probably wait till we get the Caster setting changed (I hope so, at least), see how that works out and then remove the rear sway bar.
Thanks,
Mike T.
This shop is only open Tues through Friday and is alwasy busy so tomorrow will only cover the face-to-face discussion about the Caster settings and a followup appointment will have to be made for another day.
I like to make one change at a time so I'll probably wait till we get the Caster setting changed (I hope so, at least), see how that works out and then remove the rear sway bar.
Thanks,
Mike T.
07-13-2009, 04:46 PM
#13
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Mike,
That hex fitting on each end of the upper-inner shaft is NOT a press fit!
The upper-inner shaft consists of one shaft which is an EXTREMELY tight screw-in fit in the cross member, and two bushings (the hex fittings you refer to are bushings). These bushings are a VERY tight screw-in fit in the upper A-frame.
Several weeks ago, I did a detailed post----with pictures----on a total rebuild of the front cross member/suspension.
You mentioned that the upper-inner shaft is welded to the A-frame!!!
Is the SHAFT welded to the A-frame, OR, is the BUSHING welded to the A-frame? If the shaft itself is welded to the A-frame, YOU GOT BAD, BAD, BAD problems. If the BUSHING is welded to the A-frame, you still got problems, but not so bad. What that means is that the threaded hole in the upper A-frame has become so enlarged that the bushing will not TIGHTLY screw into the A-frame.
The more I re-read your comments, the more I suspect that you have some problems at the A-frame joints, which may be causing your A-frames to "move around" during driving conditions, which is significantly changing your alignment!
Place a bottle jack (or floor jack) under the lower A-frame, remove the wheel, firmly grasp the brake drum, upper part of the suspension, or whatever you choose, and forcefully push-pull the upper part of your suspension and see how much movement there is at the upper-inner shaft/bushing joints. It SHOULD be almost non-existant. If the inner shaft joints move in-out, you definitely got problems. If that is the case, NO AMOUNT of alignment adjustments will help until the cause of the misalignment is repaired.
Tom Parsons
That hex fitting on each end of the upper-inner shaft is NOT a press fit!
The upper-inner shaft consists of one shaft which is an EXTREMELY tight screw-in fit in the cross member, and two bushings (the hex fittings you refer to are bushings). These bushings are a VERY tight screw-in fit in the upper A-frame.
Several weeks ago, I did a detailed post----with pictures----on a total rebuild of the front cross member/suspension.
You mentioned that the upper-inner shaft is welded to the A-frame!!!
Is the SHAFT welded to the A-frame, OR, is the BUSHING welded to the A-frame? If the shaft itself is welded to the A-frame, YOU GOT BAD, BAD, BAD problems. If the BUSHING is welded to the A-frame, you still got problems, but not so bad. What that means is that the threaded hole in the upper A-frame has become so enlarged that the bushing will not TIGHTLY screw into the A-frame.
The more I re-read your comments, the more I suspect that you have some problems at the A-frame joints, which may be causing your A-frames to "move around" during driving conditions, which is significantly changing your alignment!
Place a bottle jack (or floor jack) under the lower A-frame, remove the wheel, firmly grasp the brake drum, upper part of the suspension, or whatever you choose, and forcefully push-pull the upper part of your suspension and see how much movement there is at the upper-inner shaft/bushing joints. It SHOULD be almost non-existant. If the inner shaft joints move in-out, you definitely got problems. If that is the case, NO AMOUNT of alignment adjustments will help until the cause of the misalignment is repaired.
Tom Parsons
07-13-2009, 05:01 PM
#14
Race Director
I will be removing my rear sway bar shortly.
The increased rear axle roll stiffness due to my 5 1/2 leaf springs plus SSM lift bars makes the car feel a little peculiar on high speed turns, probably an oversteer condition, I wouldn't describe it as squirrely, but it doesn't feel right, rear end feels like it wants to track out, then back in, then out, etc. requiring a lot of steering wheel finessing
I sure wouldn't trust it not to want to swap ends as it got close to the limit at high speed, though at low speed it is a real road hugger.
Doug
The increased rear axle roll stiffness due to my 5 1/2 leaf springs plus SSM lift bars makes the car feel a little peculiar on high speed turns, probably an oversteer condition, I wouldn't describe it as squirrely, but it doesn't feel right, rear end feels like it wants to track out, then back in, then out, etc. requiring a lot of steering wheel finessing
I sure wouldn't trust it not to want to swap ends as it got close to the limit at high speed, though at low speed it is a real road hugger.
Doug
07-13-2009, 05:32 PM
#15
Le Mans Master
Thread Starter
Doug - Do you feel the oversteer on your '61 is caused more by the rear sway bar or the 5-leaf spring/traction bar setup you're running? I've only driven my '61 about 150 miles since it came down off the jackstands and after replacing the items I mentioned, the car does track and steer well, or at least 'had' tracked well up to this point. Other than this 150 miles worth of driving, my last experience driving a solid axle Vette was over 25 years ago so that might account for some of the lack of familiarity with these cars but I use the term 'squirrely' to describe how the car felt on a sweeping turnoff from the highway where I'd guess my exit speed was somewhere in the 40 to 45 mph range. Everything felt fine till the turn got sharper and I found a little extra steering wheel input made the car dart to the inside of the corner more than I expected. My first reaction was to correct it by turning the wheel to the outside to minimize the darting. It happened kinda quick and hadn't happened before though I believe that I hadn't tried that much steering movement off-center at that speed before either.
Tom - I just put the car back up on Jackstands (under the lower a-arms) and was unable to get any movement at that upper a-arm when pulling or pushing. Now that the wheels are off, I was able to see that the inner bushing is also 'welded' to the upper a-arm. Swell.
Tom - I just put the car back up on Jackstands (under the lower a-arms) and was unable to get any movement at that upper a-arm when pulling or pushing. Now that the wheels are off, I was able to see that the inner bushing is also 'welded' to the upper a-arm. Swell.
Last edited by Vet65te; 07-13-2009 at 05:53 PM.
07-13-2009, 06:06 PM
#16
Race Director
Doug - Do you feel the oversteer on your '61 is caused more by the rear sway bar or the 5-leaf spring/traction bar setup you're running? I've only driven my '61 about 150 miles since it came down off the jackstands and after replacing the items I mentioned, the car does track and steer well, or at least 'had' tracked well up to this point. Other than this 150 miles worth of driving, my last experience driving a solid axle Vette was over 25 years ago so that might account for some of the lack of familiarity with these cars but I use the term 'squirrely' to describe how the car felt on a sweeping turnoff from the highway where I'd guess my exit speed was somewhere in the 40 to 45 mph range. Everything felt fine till the turn got sharper and I found a little extra steering wheel input made the car dart to the inside of the corner more than I expected. My first reaction was to correct it by turning the wheel to the outside to minimize the darting. It happened kinda quick and hadn't happened before though I believe that I hadn't tried that much steering movement off-center at that speed before either.
You can take out one or the other to reduce roll stiffness. Since lighter springs or removing the lift bars isn't an option with the motor I have, the sway bar will go.
If I need further adjustments to get rid of oversteer, I will either install a heavier front sway bar, or second front sway bar.
The steering you describe sounds similar to what I was experiencing, however, my front suspension is spot on tight, so the car doesn't dart anywhere, it feels unstable to me, like the rear end wants to go further out than i want it to.
Doug
07-13-2009, 06:23 PM
#17
Le Mans Master
Thread Starter
It's Looking Like I'll be Removing the Rear Sway Bar
While I was checking the upper/inner portion of the a-arms I double checked the front wheel bearings and found a little 'click' when moving the passenger side rotor (SSBC Force 10 Disc Setup) in and out (grabing the rotor at 12 and 6 o'clock). Not a lot but more than I expected. So, popped off the dust cap and only had to snug it up about an eighth of a turn to take out that play. That's not going to cure all the ills but it's one more step towards getting the suspension set up the way it should be.
Rear Sway Bar Removal - For you guys who either are going to remove the rear sway bar or have already removed it and also have a lower traction bar setup like mine, is there an easy way get that lower sway bar bracket out from under the spring bundle without having to take 'everything' apart?
Mike T.
Rear Sway Bar Removal - For you guys who either are going to remove the rear sway bar or have already removed it and also have a lower traction bar setup like mine, is there an easy way get that lower sway bar bracket out from under the spring bundle without having to take 'everything' apart?
Mike T.
07-13-2009, 06:47 PM
#18
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a contrarian view of oversteer
Before anyone gets sufficiently ambitious enough to remove their rear sway bar, ask yourself if you really are getting classic oversteer.
Oversteer is a loss of rear cornering traction that happens before a loss of cornering traction at the front. Is that what you guys are actually experiencing? On the street? I suspect not.
I suspect you are feeling roll oversteer instead. This is an artifact of the suspension geometry on the early cars (dare I say it (close your eyes, Tom).... on C1s). Roll oversteer happens because, as the body begins to lean and the suspension compresses, the outside tire in a turn actually changes direction..... turning in more.
Without some substantial modifications to the C1 suspension, this is just the way it is. All three of our C1s do this.... one is a body off restoration, one is a low mile survivor, one is a high mile unrestored car. Only the high mile car has a rear bar.
If you have access to a bump steer gauge, and a fair amount of energy and time, you might find you can minimize the roll oversteer feel by judiciously lowering the center steering arm. Well heeled vintage racers do this and I've driven a vintage racer with this modification at Laguna Seca. Darn thing actually cornered at the limit rather well.
Bottom line, I don't think removing the rear sway bar addresses the root problem and I'm doubtful it even treats the symptom. However, if I'm wrong about the way you guys are driving on the street, then, yes, by all means, remove the rear bar because doing so will reduce true oversteer.
Jim
Oversteer is a loss of rear cornering traction that happens before a loss of cornering traction at the front. Is that what you guys are actually experiencing? On the street? I suspect not.
I suspect you are feeling roll oversteer instead. This is an artifact of the suspension geometry on the early cars (dare I say it (close your eyes, Tom).... on C1s). Roll oversteer happens because, as the body begins to lean and the suspension compresses, the outside tire in a turn actually changes direction..... turning in more.
Without some substantial modifications to the C1 suspension, this is just the way it is. All three of our C1s do this.... one is a body off restoration, one is a low mile survivor, one is a high mile unrestored car. Only the high mile car has a rear bar.
If you have access to a bump steer gauge, and a fair amount of energy and time, you might find you can minimize the roll oversteer feel by judiciously lowering the center steering arm. Well heeled vintage racers do this and I've driven a vintage racer with this modification at Laguna Seca. Darn thing actually cornered at the limit rather well.
Bottom line, I don't think removing the rear sway bar addresses the root problem and I'm doubtful it even treats the symptom. However, if I'm wrong about the way you guys are driving on the street, then, yes, by all means, remove the rear bar because doing so will reduce true oversteer.
Jim
Last edited by jim lockwood; 07-13-2009 at 06:50 PM.
07-13-2009, 06:56 PM
#19
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Rear Sway Bar Removal - For you guys who either are going to remove the rear sway bar or have already removed it and also have a lower traction bar setup like mine, is there an easy way get that lower sway bar bracket out from under the spring bundle without having to take 'everything' apart?
Mike T.
When I removed my rear anti-sway bar, I cheated and removed the lower traction bar plate (by undoing the U-bolts), and dropped the bar out from under the spring on the one side. Then did the 2 frame bolts, and then pulled the end of the bar out of the rubber under the other spring. So one side has the rubber still under the spring, and one doesn't. But easier than undoing both sides.
Eventually, I am sure I will get the rubber out of the other side, but it doesn't bother me a bit.
Plasticman
07-13-2009, 07:07 PM
#20
Race Director
My car didn't used to feel like this until I added the SSM lift bars, which increased the rear spring rate. I suppose I could just replace them with snubber bars, as I have some, but that is more work.
My car felt like it handled quiet well with the old saggy 4 leaf springs, but there was no rear wheel traction, and severe wheel hop.
This probably is roll oversteer, due to a change in rear roll stiffness with no change in front roll stiffness, causing the front wheel to turn in more. Is it a potential Oh, ****!! real oversteer, swap ends quicky problem? I don't know
What I really need is 20 minutes on a skid pad to find out what the car is going to do, but taking a $2K Bondurant class,and also being told I can't use my car on their track to boot, rules that out.
Doug
Last edited by AZDoug; 07-13-2009 at 07:11 PM.
