My Rack Conversion
Thread Starter
Racer
Joined: May 2005
Posts: 470
Likes: 1
From: Amelia Ohio
Only one bend was from the Reese factory, the other I did. It is at the center link plate, I cut a groove on the back side, used a BFH 
until I got the angle I wanted then welded the cut.
All other angles are welded. I just got back from the speed shop with my steering u-joints, so those pics will be coming soon.
Chris
until I got the angle I wanted then welded the cut. All other angles are welded. I just got back from the speed shop with my steering u-joints, so those pics will be coming soon.
Chris
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Norval, I"m kinda curious what you feel is the weakest point of the frames in holding these racks....my only comment is when turning my wheels in the garage, the amount of flex is not all that great, my bracket holds just fine, i'ts the frame that's twisting....I STILL have not gotten my top strut/support in yet, been well over a year allready..that's life....when I get it in, now that my welding buddy is on his way back home here, maybe I can get him to beef up my frame a bit, but need know what to do....
I think I finally got the height correct for the inner tie rods, but I do wonder about modding anyting further, just exactly what it would buy me, not so sure there would be any noticeable differance in street handling, and I DO enjoy that....
which brings up another thread....
GENE
I think I finally got the height correct for the inner tie rods, but I do wonder about modding anyting further, just exactly what it would buy me, not so sure there would be any noticeable differance in street handling, and I DO enjoy that....
which brings up another thread....
GENE
Intermediate
Joined: Oct 2005
Posts: 41
Likes: 0
From: NC
Oooh! Water jetted... that wouldn’t mean that you have the parts drawn out on CAD or an .IGS file would it?
I just picked up a rack and am starting on my own. I also have access to a laser cutter...
If anyone has this drawn out I would LOVE to get a copy of what you have.
Thanks,
Mike
I just picked up a rack and am starting on my own. I also have access to a laser cutter...
If anyone has this drawn out I would LOVE to get a copy of what you have.
Thanks,
Mike
Thread Starter
Racer
Joined: May 2005
Posts: 470
Likes: 1
From: Amelia Ohio
Water Jet? Lazer cutter? You guys are pampered, bust out the sawzaw and die grinder and feel what you are creating. I did all of this fab with one (count it) one Lennox blade and it was already used from another project. The pillow blocks came from 5/8" plate that I cut 10" length out of. It was fun.
Chris
Chris
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Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Originally Posted by 427V8
Water Jet, Lazer cutter, Sawzall !
I had was 1 dull hacksaw blade and no handle.
But I actually used the back side since it cut better.
I had was 1 dull hacksaw blade and no handle.
But I actually used the back side since it cut better.
OLDE joke in the construction trades.....
In that truck is every tool known to man,.....
except a phillips screwdriver....
GENE
Burning Brakes
Joined: Jul 2001
Posts: 1,038
Likes: 3
From: Clinton IL
Very cool stuff.
I know 427 had done an awesome job of documenting.
Here is my big question.
How do you know the rack is truely level and centered? How do you know the center tie rod support is at the correct offset to center?
How do you know it is at the correct height in the frame?
I have VB&P tie rod ends on my power system now. I would hope to still be able to use those. I have a center link from my 69 Camaro that I will need to check to see if the tie rod holes are the right size (so I can whack it down).
I have no problem spending the bucks and buying a pre-made Steeroid system. However, right now I don't have the buckage to spend!
I put their unit on my 69 Camaro (Grand Prix Rack) and am 100% happy with it. They do good stuff and take the guess work out of it.
I know 427 had done an awesome job of documenting.
Here is my big question.
How do you know the rack is truely level and centered? How do you know the center tie rod support is at the correct offset to center?
How do you know it is at the correct height in the frame?
I have VB&P tie rod ends on my power system now. I would hope to still be able to use those. I have a center link from my 69 Camaro that I will need to check to see if the tie rod holes are the right size (so I can whack it down).
I have no problem spending the bucks and buying a pre-made Steeroid system. However, right now I don't have the buckage to spend!
I put their unit on my 69 Camaro (Grand Prix Rack) and am 100% happy with it. They do good stuff and take the guess work out of it.
Le Mans Master
Joined: Sep 2000
Posts: 9,078
Likes: 7
From: DFW TX
Cruise-In VII Veteran
St. Jude Donor '07
Originally Posted by Rendler
Oooh! Water jetted... that wouldn’t mean that you have the parts drawn out on CAD or an .IGS file would it?
I just picked up a rack and am starting on my own. I also have access to a laser cutter...
If anyone has this drawn out I would LOVE to get a copy of what you have.
Thanks,
Mike
I just picked up a rack and am starting on my own. I also have access to a laser cutter...
If anyone has this drawn out I would LOVE to get a copy of what you have.
Thanks,
Mike
Dullsawsall guys - Here is my arrangement with the Lazorjet/Waterjet people. There is a lady at work whos husband works for a metal fab company, I give her the templates needed. She bakes brownies for the guys that cut them out, then I give her haircare products that my wife gives me.
So everyone is happy and it works. Trust me, I do my fair share of cutting with zip cut wheels and dull blades. 
Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
Originally Posted by mrvette
Norval, I"m kinda curious what you feel is the weakest point of the frames in holding these racks....
GENE
GENE
The GM corvette manual recommends the hole should be closed. I close this hole and at the same time plate over the entire outside of the frame in this area and go right around the corner.
I don't have a clue as to how the frame flexes with your R&P put anytime you are dealing with suspension or steering you can not be too rigid. You don't want the bracket flexing at all, Zero tolerance for flex.
The wieght penalty for a heavy bracket over a light one is a few pounds and it is well worth the weight.
Build anything related to your steering as rigid as possible.
I also feel a spreader bar is a necessity and very simple to build or install.
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Chris, with your fabbing abilities and car knowledge, I just can't SEE you doing anything other than making your own rack install....
come one guy, I KNOW you can do it....jeez...gotta be what?? 3-4 of us guys here to help with dimensions/specs...
GENE
come one guy, I KNOW you can do it....jeez...gotta be what?? 3-4 of us guys here to help with dimensions/specs...
GENE
Burning Brakes
Joined: Jul 2001
Posts: 1,038
Likes: 3
From: Clinton IL
Originally Posted by mrvette
Chris, with your fabbing abilities and car knowledge, I just can't SEE you doing anything other than making your own rack install....
come one guy, I KNOW you can do it....jeez...gotta be what?? 3-4 of us guys here to help with dimensions/specs...
GENE
come one guy, I KNOW you can do it....jeez...gotta be what?? 3-4 of us guys here to help with dimensions/specs...
GENE
Good stuff!
However, there are times when getting already done has its merit.
I am ready to do this mod, just not comfortable with knowing exactly where to float the rack in place to make sure it is in the most correct position.
In fact, I will be pulling my power steering gear off the car this weekend after making multiple measurements and photos to document locations, spacing, etc. I would like to go ahead and weld the mounting brackets in place once they are there so they simply become part of the frame as if the factory intended on them to be there.
Race Director
Joined: Dec 1999
Posts: 16,945
Likes: 9
......
Originally Posted by 69Myway
How do you know the rack is truely level and centered? How do you know the center tie rod support is at the correct offset to center?
Measure from left to right lower cross shaft and the center between those is the rack center. The tie rod mounting plate position all depends on the upepr and lower cross shafts, the steering arm and the lwoer control arm. Take a good look at the diagram that was posted, see how it finds the instantaneous center from the 2 arm angles extending and then the tie rod angle is determined by the IC and the steering arm. The tie rod length is determined by the imaginary line between the 2 cross shafts and there it intersects your imaginary tie rod line from the instantaneous center. The only thing to note is that the upper cross shaft is angled so you ahve to take the fore/aft position into consideration. Best is to fab up a long bar that mimics the cross shaft, so that you can tie a string to it as far back as the rack sits (directly above the tie rod hole, use a plumb bob) and then you can get the geometry just right
How do you know it is at the correct height in the frame?
just tuck it in there as tight as possible, tie rod inner position can be customized w/ center bracket/mount plate
I have VB&P tie rod ends on my power system now. I would hope to still be able to use those. I have a center link from my 69 Camaro that I will need to check to see if the tie rod holes are the right size (so I can whack it down).
Outer ends remain the same, inners depend on what kind of mounting system you have, tapered like the thread starter will accept stock tie rod ends, otherwise it's 5/8th heims.
Measure from left to right lower cross shaft and the center between those is the rack center. The tie rod mounting plate position all depends on the upepr and lower cross shafts, the steering arm and the lwoer control arm. Take a good look at the diagram that was posted, see how it finds the instantaneous center from the 2 arm angles extending and then the tie rod angle is determined by the IC and the steering arm. The tie rod length is determined by the imaginary line between the 2 cross shafts and there it intersects your imaginary tie rod line from the instantaneous center. The only thing to note is that the upper cross shaft is angled so you ahve to take the fore/aft position into consideration. Best is to fab up a long bar that mimics the cross shaft, so that you can tie a string to it as far back as the rack sits (directly above the tie rod hole, use a plumb bob) and then you can get the geometry just right
How do you know it is at the correct height in the frame?
just tuck it in there as tight as possible, tie rod inner position can be customized w/ center bracket/mount plate
I have VB&P tie rod ends on my power system now. I would hope to still be able to use those. I have a center link from my 69 Camaro that I will need to check to see if the tie rod holes are the right size (so I can whack it down).
Outer ends remain the same, inners depend on what kind of mounting system you have, tapered like the thread starter will accept stock tie rod ends, otherwise it's 5/8th heims.
Thread Starter
Racer
Joined: May 2005
Posts: 470
Likes: 1
From: Amelia Ohio
Okay, I will get measurements and more specific proceedures for centering and the sort. I'm working right now but I get something together today or tomorrow morning. I want to get my u-joints in first.
Chris
Chris
Instructor
Joined: Jan 2003
Posts: 143
Likes: 0
From: Vancouver Wa
I would like to know more about this conversion as I think the stock steering system in my 81 sucks even when rebuilt, vague control and road feel is undesirable. I take it that you are doing a rack and pinion conversion and you got the rack from a grand am? Did you have it rebuilt or was that not necessary? How did you make the connection from the steering box to the rack? How much does this conversion cost? Mid America has a complete conversion kit for $1,250.00 but my budget doesn’t allow for this and probably won’t for a long time. I take it that rack and pinion feels a whole lot better then a pitman arm going to a control valve system. This just seems and feels kind of sloppy to me and is not what I have in mind for my vette.
C6 the C5 of tomorrow
Joined: Nov 2000
Posts: 6,665
Likes: 2
From: Twin Cities Minnesota
Originally Posted by evalu8r
Okay, I will get measurements and more specific proceedures for centering and the sort. I'm working right now but I get something together today or tomorrow morning. I want to get my u-joints in first.
Chris
Chris
What did you end up with for tie rod lengths and center bracket width and offset?
I'd like to compare it to my system and update my website.
Brian,
You can use a used rack as long as it's in good shape, just get one out of a 92 or newer Grand Am. Not too new though, the rack must be behind the front wheels, bolted to the firewall. The newer cars went to front steer I thinks.
There are some pics on my web page, under Rack and pinion, http://www.corvetteforum.net/c3/427v8/
cost is much cheaper, but you need to be able to weld and cut 1/4" steel and it depends on how good you are at the junkyard crawl.
Steering feel is amazing, very tight.
One gotcha is the power steering pump is too much for the rack and makes the steering light, there are fixes for that too, from the cheap, weld up the flow valve to specially modified pumps.
Keith
Last edited by 427V8; Feb 3, 2006 at 03:23 PM.
