Rear Spring Issue
Thread Starter
Pro
Joined: Jan 2007
Posts: 524
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From: Auckland New Zealand
Rear Spring Issue
When pulling rear wheels off to replace rotors and park brake shoes I discovered a 6mm thick spacer
between the wheel and the drive flange – on the right rear wheel only a bit odd I thought.
When it all went back together, there was no way I was going to put one oddball spacer back on.
After bolting wheel up, found it was dragging badly on something under the car. On further inspection, the inside rim was binding on the end of the transverse leaf spring and it's associated cup washers.
For now I have had to put the spacer back on whilst I scratch my head a bit more.
My first thought is, the steel wheels on the car are not the original and have a slightly different offset, which is set more towards the car centreline.
On the offending end that fouls the wheel I measured the distance from centre of diff housing out to end of spring. This distance is 6mm longer than same measurement on the left rear side.
The measurement from spring centre-bolt to end of leaf, is the same on both sides and the centre-bolt appears to be centred between the bolts at the rear of diff housing.
Anyone have any clue as to what is going on here?
Neville
between the wheel and the drive flange – on the right rear wheel only a bit odd I thought.
When it all went back together, there was no way I was going to put one oddball spacer back on.
After bolting wheel up, found it was dragging badly on something under the car. On further inspection, the inside rim was binding on the end of the transverse leaf spring and it's associated cup washers.
For now I have had to put the spacer back on whilst I scratch my head a bit more.
My first thought is, the steel wheels on the car are not the original and have a slightly different offset, which is set more towards the car centreline.
On the offending end that fouls the wheel I measured the distance from centre of diff housing out to end of spring. This distance is 6mm longer than same measurement on the left rear side.
The measurement from spring centre-bolt to end of leaf, is the same on both sides and the centre-bolt appears to be centred between the bolts at the rear of diff housing.
Anyone have any clue as to what is going on here?
Neville
Le Mans Master
Joined: Nov 2000
Posts: 7,246
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From: Going too fast over the hill. Iowa
Did you switch/measure the wheels left to right to see if they are the same?
Did you measure the halfshafts to see if they are the same length?
I have seen both problems.
Did you measure the halfshafts to see if they are the same length?
I have seen both problems.
Le Mans Master
Joined: Mar 2005
Posts: 7,631
Likes: 11
From: Rocklin California
Welcome to the world of many surprises. I have spent many hours with tape measure, and thinking cap. Trying to chase down how these cars are supposed to be and what someone prior to me has done. It's a real challenge. But you should get some good advice here on the forum. Good luck 
Team Owner
Joined: Mar 2003
Posts: 26,118
Likes: 1,874
From: Greenville, Indiana
"On the offending end that fouls the wheel I measured the distance from centre of diff housing out to end of spring. This distance is 6mm longer than same measurement on the left rear side."
I don't know if the spring is supposed to be centered on the differential but if it is, sounds like you've found your problem if you measured correctly. That would mean your spring isn't seated and you'd likely get a lean. Also, your trailing arm bolts probably would be slightly canted to one side if the spring was offset.
As an idicator only, how does your tire/fender clearance compare side/side at the rear?
I don't know if the spring is supposed to be centered on the differential but if it is, sounds like you've found your problem if you measured correctly. That would mean your spring isn't seated and you'd likely get a lean. Also, your trailing arm bolts probably would be slightly canted to one side if the spring was offset.
As an idicator only, how does your tire/fender clearance compare side/side at the rear?
Le Mans Master
Joined: Jun 2004
Posts: 9,015
Likes: 331
From: Southeast Missouri
Without checking my wheels, I would suspect that your spring might not only be off of center that much from side to side, but also that your wheels are not original width/offset. Six millimeters is damned little, and I believe the clearance between rim and spring/washer should be more than that. (Like I said, without checking!!!)
Thread Starter
Pro
Joined: Jan 2007
Posts: 524
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From: Auckland New Zealand
Halfshafts - well I had agood look at them and they appear to be original. I will give them a measure though.
Thread Starter
Pro
Joined: Jan 2007
Posts: 524
Likes: 12
From: Auckland New Zealand
"On the offending end that fouls the wheel I measured the distance from centre of diff housing out to end of spring. This distance is 6mm longer than same measurement on the left rear side."
I don't know if the spring is supposed to be centered on the differential but if it is, sounds like you've found your problem if you measured correctly. That would mean your spring isn't seated and you'd likely get a lean. Also, your trailing arm bolts probably would be slightly canted to one side if the spring was offset.
As an idicator only, how does your tire/fender clearance compare side/side at the rear?
I don't know if the spring is supposed to be centered on the differential but if it is, sounds like you've found your problem if you measured correctly. That would mean your spring isn't seated and you'd likely get a lean. Also, your trailing arm bolts probably would be slightly canted to one side if the spring was offset.
As an idicator only, how does your tire/fender clearance compare side/side at the rear?
Using a plumb bob from body, hanging down past centreline of spinner and measuring to wheel rim,there is a 10mm difference. This may not be a good indicator, as body may not be exactly centred on chassis? I'm not sure how good this was ex factory. The body mounts appear to be original and untouched. They are certainly quite old and a bit cracked.
One other thought I had was the centrebolt could be sheared off and spring has moved.
I have had a go at cracking spring mounting bolts - no luck. I do not think they have ever been undone, similar to alot of other parts on car - most things seem to have never been touched.
I will persevere and soak bolt thread in WD40 for a while. I will also measure halfshafts but would be surprised if they were differrent.
I cannot see that it is anything to do with the trailing arms, as they just locate the axle.
Neville
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Team Owner
Joined: Mar 2003
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From: Greenville, Indiana
If you're saying the RR wheel is 10 mm farther o/b than the left wheel and then you subract the approximately 6mm spacer, that leaves a net offset of 4 mm. Is that correct. If it is, that seems to be within range of many cars.
I think you either have a bastard wheel or your spring has shifted. WD 40 is a very poor penetrating oil. You might try something else.
You should be able to measure from the centerline of your spring bolts to the tip end of the spring to see if it's shifted over.
I think you either have a bastard wheel or your spring has shifted. WD 40 is a very poor penetrating oil. You might try something else.
You should be able to measure from the centerline of your spring bolts to the tip end of the spring to see if it's shifted over.
Thread Starter
Pro
Joined: Jan 2007
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From: Auckland New Zealand
To ID the wheels, what markings would I be looking for?
What inner offset if they are genuine 66 corvette steel wheels?
Last edited by Nev Williams; Jul 7, 2007 at 10:03 PM.
Thread Starter
Pro
Joined: Jan 2007
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From: Auckland New Zealand
Update -
With the car sitting level on wheels the rim does not interfere. It only seems to be when car is jacked up and wheels are hanging down at full travel.
With spacer removed the rim does not rub, but is still what I would consider very close (about 12-15mm - 5/8" clear) - is this normal?
I would have thought, even when the wheel is in full down position, there should be no interference.
With the car sitting level on wheels the rim does not interfere. It only seems to be when car is jacked up and wheels are hanging down at full travel.
With spacer removed the rim does not rub, but is still what I would consider very close (about 12-15mm - 5/8" clear) - is this normal?
I would have thought, even when the wheel is in full down position, there should be no interference.
Race Director
Joined: Nov 2000
Posts: 10,340
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From: Beverly Hills (Pine Ridge) Florida
Possible too much clearance in the rear spindle/wheel bearings. GM Spec was .001 to .007" end play (from the factory) and couple that with a wear, can allow the wheel to move around quite a bit. If the bearing have not been changed / checked, would recommend doing so. "Normally" the original bearing were shot in the 60K to 70K miles range.
Good luck,
Plasticman
Good luck,
Plasticman
Thread Starter
Pro
Joined: Jan 2007
Posts: 524
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From: Auckland New Zealand
Possible too much clearance in the rear spindle/wheel bearings. GM Spec was .001 to .007" end play (from the factory) and couple that with a wear, can allow the wheel to move around quite a bit. If the bearing have not been changed / checked, would recommend doing so. "Normally" the original bearing were shot in the 60K to 70K miles range.
Good luck,
Plasticman
Good luck,
Plasticman
I have given in to temptation and driven it round the block a few times !!!
Neville