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rear end help needed

cwerve74

Well-known member
Joined
Sep 17, 2003
Messages
132
Location
Memphis
Corvette
1974 454MT red conv
I have completed the rear end rebuild but am not happy with the result. Need help understanding what is wrong and what needs to be done to fix it. When I got the car back on the ground the tail seem to high. I have several photos to help in understanding the problem. What was done . New differential cover, rebuilt t-arms rebuilt half shafts, New camber arms., New bushings all around, new spring. I don't see what is wrong other than the tail is to high and the half shafts & camber arms seems at the wrong angle. I think the spring is some how involved but don't see the root casuse. Help. High tail photo is a composit of two pictures so it looks strange but what I wanted tp show was the wheels in the wheel arch. The photo of the half shaft angle is in next post.
 
Photo of half shaft and camber arm. Angle seems top be not parrallel with teh ground.
 
One additional photo showing complete rear .
 
Have you rolled the vette around to help it settle or did you just set it down and not like the way it looked?
In the second pic, it looks like the bottom of the tires are leaning in too much, (like it was freshly lowered from the jack or hoist) and it could be that it just needs to move around a bit so the tires settle to where they normally ride while driving.

I believe I've read in other posts about adjusting some tension bolts on the spring that affect ride height...I can't recall a specific thread but perhaps you can do a search?
Use key words like; rear spring, ride height, rear spring adjustment...
Heidi
 
If you're lucky, all you'll need to do is release the torque on the trailing arm bushing nut and bolt, and let the car settle to it's proper height after you bounce it up and down a few times. Suspension bushings must only be torqued with the weight of the car on it's wheel and at normal ride height.

If you're not lucky, you've bought yourself one of the aftermarket springs that are arched incorrectly which give you the wrong ride height. Unfortunately, there's no real correct spring on the market to exchange it with. You can either put your original spring back on (most of them are still serviceable) or get longer bolts that join the spring ends to the trailing arms.

My guess is that it will be the new spring that's giving you the problem.

:beer
 
You can get the rear lower with longer spring bolts. I think mine are like 10 inches. Yours look much smaller.
I'll see if I can find a link for ya.
 
Check your spring bolts like the other guys said. Use 8" at least to lower to about 28"+/- 1/2" to center of fender well.
Spring should be loaded with the weight of the car on it. what I do is use the siisor jack to level the rear T arms,snug the front bolt, torque the 4 spring bolts to 50 ft/lbs, use a level on the rotor to bring in rough alignment to 1/8" neg camber,install the spring end links using the longer bolts, drop car and roll back and forward to settle the suspension, slid under and torque the 4 spring bolts to 75 ft/lbs, torque front bolt to 50ft/lb? double check this one, adjust height. Should be ok or very close
 
All of the available reproduction springs create the wrong ride height (too high), which is why most of the Vette catalog suppliers sell 10" extra-long link bolts and Nylok nuts to compensate for the incorrect spring arch/load rate; a correct spring is just about perfectly flat under normal load.

That's why you're always better off to have the original spring professionally re-arched/rebuilt (assuming it hasn't lost a lot of material due to corrosion). There's only one place with the facilities, experience, heat-treat, annealing, and shot-peening capability, and know-how to do it right - Eaton-Detroit Spring (www.eatonsprings.com). I have an article on that process coming up in six weeks in the March issue of "Corvette Enthusiast" magazine.
:beer
 
I love this forum. OK I have done most of the suggestions. loosened & retorked, bounced & rocked it a little got about an inch out of it. Let me comment on the replys.

78SilvAnniv

Yes I had not move the car since it was lowered. I had done a prilim Camber adjustment but that was with the T-arm 3 inches higher so the camber is not zeroed at this ride hight.

Vettehead Mikey

I think I am falling into the unlucky group. Did some measurements after settling the car. See attached diagram. The D diamentions is 2 inches to tall. and K is 1 3/4 too tall. The spring material on the new one is thicker than the orginal. The whole stack of springs is about 3/4 "more than the orginal. On the other end the spring cushions have not compressed much I would say there is about 3/4 to 1 inch on that side. Those two measurements are most of the problem.

c5d
Did not know the orginal could be recondidtioned. My spring looks perrty sad but I will investigate that as an option. Looks like JohnZ has a link for that .

coupeman

Wonderfull set of instructions. I did most of them thru some set of trial & error. This is my 1st project car. I will be getting 8 inch bolts as I think that will be a good temp fix (maybe perminate). I believe if I run it like it is the half shafs will have a half life. I want to look at putting back in the orginal spring also.

To all
Last night I was kind of depressed ( my wife has a different description of my mood) today if feel good again with a plan . Thanks to all
 
Did you torque the spring mount bolts with the car on the ground? If not, retorque them with the full weight of the car on the spring. This should help some.
Then take it out and drive around the block to settle the spring. When you raise the wheels off the ground and just drop it, the tires are closer together than normal and causes it to be higher. It needs to be rolled several feet back and forth to unscrub the tires. Driving around the block is better. It's a good idea to check the torque on the spring bolts again.
Now check ride height and adjust with longer bolts if necessary. You can get them from a good hardware store. It's a 9/16 fine thread, grade 8, start with 8 inches long. Use nylock nuts, and you can drill and pin them if you wish. It may settle a little more with the spare tire and a few weeks time.
 
Cwerve74,

I experienced a very similar situation with the rebuilding of the rear suspension in my 81, and even though I tried to get the camber adjusted as even as I could, the rear height did not improve until I had the car aligned (all 4 wheels).

I think that JonhZ may be right about the lack of quality control outside Eaton. I almost bought the spring from Eaton, but instead I got it from Corvette Central, and I don't know who supplies them the springs.

However, it does seem that almost 30 years in a spring would be enough for it to loose some of its load/spring rate and reliability. I had a chance to compare the old and new, and while uninstalled, they seemed to have the same shape and dimensions. I placed the new one over the old one while laying on the ground as a horse shoe would, and did not noticed any difference beyond the the missing rubber cushion cup from the new one that is usually fitted into the factory, and the corrosion and busted aluminum shims in my old one.
 
Pigpen you must have better hardware stores by you. I went to what I thought to be my best bet and can up short. The longest they had was 6 inches(same as currently installed). I found an online retailer that has 8 inch bolts. But as I studied this long bolt option it looks to me that by doing this you move the spring end and cushion very close to the rubber part of the tire. My estimate is about 1/2 inch clearence. see picture of my mock up of a 8 inch bolt. Is there enough flex in the tire to cause an interfearence? Has anyone experienced a tire rub with this long bolt option?
 
You do have to be careful with the tires. I use the 8" bolts but the tires are the stock size 225-70-15 THe only place I found the correct bolts was through a vette supplier like Vette Brakes cost is about $18 but you should get them where you are in a day or two UPS.
 
...or you could use this opportunity to slap on some fat and tall slicks in the back ;).

I have a question, you guys are talking about changing out the spring bolt to a longer one, so he can lower it even more. But, if he has the stock bolt on there, shouldn't the spring work towards the bolt, and not the other way around? There aren't any aftermarket springs that are close to the originals?

And, why doesn't GM still make these for our old Vettes?

Thanks! :D

TR
 
It's a bit hard to see, but this is what mine looks like. I have it lowered as much as possible. I have stock tires so I do not have a issue with clearance...
That is a good question though. How much play would a tire or bolt slide horizontally during normal driving habits? Is 1/2 inch enough? Anyone not running stock size tires with the 8 inch bolt?
 
JrdnsEdu

Thanks for the photo. I did a little enhancment plus and attached your photo. I marked the center to the camber strut and wheel rim. If those are 8 inch bolts you have about 1 1/2 inchs of thread below the nut. You are not far from the stock length. I ordered long bolts but I have convinced my self I will need most of the length to get the correct body height. Plus I am real concerned about the clearenace between the tire at that length. I am going to call Corvette Central and talk to the tech person. I am about 80% of the way toward returning the spring. But if I am going to replace the spring just not sure if I get another one some place else that it fits any better. Does anyone have experience with the stock 9 leaf rear spring from some retailer that they thought was a good fit?
 
I haven't had a chance to look at my car and the picture is difficult to see but since the spring and tire both attach to the trailing arm won't they maintain their space as they move in tandem, particularly with the arch in the spring wanting to move toward the center of the car as it drops down and pulling the bolt in with it.
 
CWERVE74,

There is a bolt supply house just off Winchester near the Airport. I can't think of the street to turn on but it is right at the end of the runway. Go down to first street and turn left and it will be on your left. There is also another fastener supply house on Lamar and Winchester. I think either will have your 8" bolts.

Randy:w

I went to what I thought to be my best bet and can up short.
 
The one I used is on Sanderwood Drive

Active Bolt and Screw CO
730 South Main Street, Memphis, TN 38103
(901) 523-1557
map | driving directions



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Assembly Component Systems
283 Cumberland Street, Memphis, TN 38112
(901) 324-5101
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Eagle Sales Inc
1340 Farmville Road, Memphis, TN 38122
(901) 458-6133
(901) 458-4144 (fax)
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sales@eaglesales.com



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Fell & Company International
3266 Winbrook Drive, Memphis, TN 38116
(901) 332-6669
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Maintenance Supply & Fastener CO
2890 Sanderwood Drive, Memphis, TN 38118
(901) 362-1720
map | driving directions
 
CWERVE74- I measured my bolts this morning and they are 10", not 8". Hope that helps.
 

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