Swapping Bolts Improves Handling?
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St. Jude Donor '07
Swapping Bolts Improves Handling?
I read in a Corvette Fever that there are a couple bolts in the front end that can be swapped to improve handling. Swapping them requires an alignment, but they claim positive results. It claimed that it transferred more steering control to the driver. I wish I remembered more of the article.
Anyone else heard of something like this? Worth doing while I rebuild my suspension?
Anyone else heard of something like this? Worth doing while I rebuild my suspension?
Team Owner
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From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
I've heard some refer to flipping the upper control arm rods around for more castor, but I measured them, and they appear to be the same either way you mount them.
Racer
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You're all so close. And yes, rocco, it is that easy. Well sort of. I remember doing that article. It was on an '84 Corvette. I'd have to go back and find the article to remember the exact years that it applies to but basically, its for the early C4s. You don't swap out the arms but actually the bushings that go between the arms and the frame. If you notice, the front ones are shorter than the rear ones. if you swap them, that moves the upper ball joint toward the rear of the car which gives it more caster. The benefit is that the car doesn't "feel as nervous" when driving it and irregularities in the road don't affect it as drastically. The owner of the car that we did the swap on just mentioned the other day how much that improved the handling. It won't give you more g's in a turn but it makes straight line driving much more enjoyable. Hope this helps.
Andy Bolig
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Racer
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From: Lancaster Lancashire
Originally Posted by C5rider
You're all so close. And yes, rocco, it is that easy. Well sort of. I remember doing that article. It was on an '84 Corvette. I'd have to go back and find the article to remember the exact years that it applies to but basically, its for the early C4s. You don't swap out the arms but actually the bushings that go between the arms and the frame. If you notice, the front ones are shorter than the rear ones. if you swap them, that moves the upper ball joint toward the rear of the car which gives it more caster. The benefit is that the car doesn't "feel as nervous" when driving it and irregularities in the road don't affect it as drastically. The owner of the car that we did the swap on just mentioned the other day how much that improved the handling. It won't give you more g's in a turn but it makes straight line driving much more enjoyable. Hope this helps.
Andy Bolig
Corvette Enthusiast
Andy Bolig
Corvette Enthusiast
If you could find the article and post which mag & issue, it would be great. I seem to remember reading about this also, but my old mags aren't readily accessible to find it. If I knew what I was looking for, that would be much easier. I seem to remember it only being applicable to the 84-87's, as the 88 on cars as we know had a different front suspension geometry. I would gladly trade a bit of turn in for improved straight line stability. Obviously this would not suit an Autocrosser I suppose.
I have most vette & C/Fever issues from around 1993 on. (somewhere)
Dave
Le Mans Master
Joined: Dec 2002
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From: Seattle Area WA
Originally Posted by joshwilson3
So, you put the rear bushings on the front, and the front bushings on the rear? Or do you leave the rear bushings alone and put another set of rear bushings on the front?
Please let us know what years this applies to.
thanks
Please let us know what years this applies to.
thanks
Le Mans Master
Joined: Jan 2002
Posts: 9,036
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From: Edmonton AB
On the '89 there are dished washers between the upper control arm
and the frame horns that the bollts pass through. During an alignment
shims are added/removed between these washers and the horns.
GM identifies these as Position 1 (front - thick) and Position 2 (rear
- thin). On the '89, these are solid circular washers - flat on one
surface, concave on the other. They are not bushings (no rubber
or urethane component.)
I read of an instance where the object was to reduce caster.
A female owner complained that the high steering effort made her car
unpleasant to drive. Switching locations (on fr/rr upper control arm
bolts) permitted less caster to be dialed in.
If it were possible to switch positions and still achieve the factory
caster setting, then nothing would have been gained. The amount
of caster needs to change (less = reduced self aligning characteristics
and thus less effort. More = the opposite.) Switching the washers
merely provides a different range of adjustment.
.
and the frame horns that the bollts pass through. During an alignment
shims are added/removed between these washers and the horns.
GM identifies these as Position 1 (front - thick) and Position 2 (rear
- thin). On the '89, these are solid circular washers - flat on one
surface, concave on the other. They are not bushings (no rubber
or urethane component.)
I read of an instance where the object was to reduce caster.
A female owner complained that the high steering effort made her car
unpleasant to drive. Switching locations (on fr/rr upper control arm
bolts) permitted less caster to be dialed in.
If it were possible to switch positions and still achieve the factory
caster setting, then nothing would have been gained. The amount
of caster needs to change (less = reduced self aligning characteristics
and thus less effort. More = the opposite.) Switching the washers
merely provides a different range of adjustment.
.
Racer
Joined: Oct 1999
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You are correct Slalom. It would be increasing caster, which would give the car more self-aligning tendancies. It's not simply swapping out the bushings but the fact that the wider busing up front now provides for more caster once the car is re-aligned. I'll have to go back and check the issues to see which one it was in. Too much water under that bridge to remember. My mind's not that good anymore.
Andy Bolig
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Andy Bolig
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Thread Starter
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St. Jude Donor '07
OK,
Found it in the August, 2001 (Volume 23, Number 8) issue of Corvette Fever. The article was written by our own Andy Bolig @ www.corvetteclinic.com Work performed by Chris Petris.
Base Alignment was 3.5 degrees caster.
What they did was swap the larger bushing from the rear bolt of the cross shaft and move it to the front bolt between the cross shaft and frame. They did NOT replace the shims that they removed in the process. It was then aligned to the following specs:
New Alignment Specs
Front: +6.5 - +7.0 Caster, -.25 Camber
Rear: -.5 Camber, Zero Toe
This mod apparently makes the car 'feel' like it wants to go forward instead of darting from side-to-side. It works for '84-'87 years. I might give this a go on my '85 when I rebuild the suspension this Spring.
Discussion?
-Kyle
Found it in the August, 2001 (Volume 23, Number 8) issue of Corvette Fever. The article was written by our own Andy Bolig @ www.corvetteclinic.com Work performed by Chris Petris.
Base Alignment was 3.5 degrees caster.
What they did was swap the larger bushing from the rear bolt of the cross shaft and move it to the front bolt between the cross shaft and frame. They did NOT replace the shims that they removed in the process. It was then aligned to the following specs:
New Alignment Specs
Front: +6.5 - +7.0 Caster, -.25 Camber
Rear: -.5 Camber, Zero Toe
This mod apparently makes the car 'feel' like it wants to go forward instead of darting from side-to-side. It works for '84-'87 years. I might give this a go on my '85 when I rebuild the suspension this Spring.
Discussion?
-Kyle
Last edited by williammackean; Nov 18, 2005 at 01:54 PM.
Le Mans Master
Joined: Jan 2002
Posts: 9,036
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From: Edmonton AB
Adding 3º of caster will noticeably increase the self-aligning nature
of the steering. -0.25º camber is not bad, there will be little if any
increase in tire wear IMO.
All I would add is that you insist that both sides be set to the same
values. Get the before and after printouts. If they can't get both
sides to the numbers you want, permit them to scale back the numbers
and adjust to the lowest common denominator - as long as this is the
same for both sides.
(I harp on this because I continue to find people who adjust for road
crown - what an antiquated concept.)
.
of the steering. -0.25º camber is not bad, there will be little if any
increase in tire wear IMO.
All I would add is that you insist that both sides be set to the same
values. Get the before and after printouts. If they can't get both
sides to the numbers you want, permit them to scale back the numbers
and adjust to the lowest common denominator - as long as this is the
same for both sides.
(I harp on this because I continue to find people who adjust for road
crown - what an antiquated concept.)
.
Thread Starter
Race Director
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St. Jude Donor '07
I harp on this because I continue to find people who adjust for road crown - what an antiquated concept.
I have always thought that to "align" something meand to make it level and true for its intended purpose. The thought of creating an intentional imperfection based upon an assumed behavior seems counterproductive to me. It also sounds rather prejudiced.
I totally follow you on the LCD concept. Good thought!
Racer
Joined: Aug 2002
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From: Lancaster Lancashire
Originally Posted by JoBy
Caster. +6 degrees +/- 0.5 degrees
Camber. +0.8 degrees
Toe 0
The changes made in the article aren't a 'major' change to these specs; and contradict the Corvette Fever article somewhat. Where the 84/85/86 cars different to the 87 (last of the first type suspension setup)?
I also read (TPiS insider hints) that the standard settings were 'way out' from the factory???
Anyone have the factory (Helm manual) specs for 84-86 cars?
Also, as an aside, I thought GM increased Front Positive Caster on the 88+ cars? Anybody have those specs for comparison?
Dave
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From: Long Island NY
Team Owner
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From: Northern, VA
St. Jude Donor '15
"In honor of jpee"
Originally Posted by Slalom4me
On the '89 there are dished washers between the upper control arm
and the frame horns...
I read of an instance where the object was to reduce caster.
A female owner complained that the high steering effort made her car
unpleasant to drive. Switching locations (on fr/rr upper control arm
bolts) permitted less caster to be dialed in..
and the frame horns...
I read of an instance where the object was to reduce caster.
A female owner complained that the high steering effort made her car
unpleasant to drive. Switching locations (on fr/rr upper control arm
bolts) permitted less caster to be dialed in..