Leaf Spring Help needed Bolts won't seat
Thread Starter
Instructor
Joined: Apr 2001
Posts: 178
Likes: 4
From: Hendersonville TN
Leaf Spring Help needed Bolts won't seat
I just installed a new Vette Brakes 9 Leaf spring on my 75 and the two forward bolts that go into the differential cover will not seat completely. The two rear bolts that go through the tabs on the differential cover are fine. These are the original bolts that were in place with the old spring. All four are the same length. I have cleaned the treads with a wire brush and tried all four bolts in the forward two holes with no success. I have tried tightening them with the no load on the spring and with the spring loaded. I have torqued all four to 70lbs. Still no luck. Has any one had a similar problem? :confused:
Safety Car
Joined: Sep 2000
Posts: 4,679
Likes: 6
From: Charles Town WV
Re: Leaf Spring Help needed Bolts won't seat (eddadams)
When I installed my new spring the cushions between the springs made the leaf about 1/2 an inch thicker. I ended up using slightly longer bolts. After the cushions compress a little I'm going to check them out. Be careful with the forward holes, they are blind holes and you don't want the bolt bottoming out in the hole.
Make sure you have the weight on the wheels when you're torquing the bolts down, you can break the rear cover if you're not careful.
Make sure you have the weight on the wheels when you're torquing the bolts down, you can break the rear cover if you're not careful.
Le Mans Master
Joined: Sep 2000
Posts: 6,036
Likes: 2
From: Westfield Indiana
Cruise-In III Veteran
Cruise-In IV Veteran
Cruise-In V Veteran
Re: Leaf Spring Help needed Bolts won't seat (eddadams)
When I installed my spring, I put a jack under it, raised it up in place, and then started all four bolts. When you say they "won't seat", do you mean that they aren't catching any threads? Or that they bottom out before reaching the spring plate? There is a small protrusion on top of the spring that MUST go into a matching hole on the bottom of the differential. I used the jack to hold up the spring while I manuevered it around to get it in place. Can be a major pain. Just have patience.
Le Mans Master
Joined: Aug 2001
Posts: 6,213
Likes: 1
From: South Alabama
Re: Leaf Spring Help needed Bolts won't seat (sharklover)
When I installed my spring, I put a jack under it, raised it up in place, and then started all four bolts. There is a small protrusion on top of the spring that MUST go into a matching hole on the bottom of the differential. I used the jack to hold up the spring while I manuevered it around to get it in place. Can be a major pain. Just have patience.
Went and got a pal and we ended up placing a floor jack under each spring end and together we jacked up the ends until the spring was compressed and flat (kept the original jack under the center to keep it in place). Now the spring mount plate was flush and everything went right together. Moderately tightened everything up, put everything else back together and torqued the center bolts with the car on the ground and retorqued after several miles. Have had no problems since but it was a good learning experience.
Race Director
Joined: Apr 1999
Posts: 10,866
Likes: 717
From: Beverly Hills/Pine Ridge Florida
Re: Leaf Spring Help needed Bolts won't seat (Cajun75)
I know nothing of the VB spring, but I would check the thickness of your original against the replacement. The front holes are blind. If the bolts are too long, and you keep torquing them, you'll break through the bottom of the diff case, and end up with a rear end gear oil leak. You may need to buy shorter bolts. Also, never torque the 4 spring bolts until you have weight on the spring. That's a sure fire way to break an ear of the case. Hope this helps. Chuck
Thread Starter
Instructor
Joined: Apr 2001
Posts: 178
Likes: 4
From: Hendersonville TN
Re: Leaf Spring Help needed Bolts won't seat (Chuck Gongloff)
I too used a jack to hold the spring and the plate in place as I tightened the 4 bolts. The problem is the forward two are bottoming out before tightening flat against the plate. So I guess I will have to get short bolts. I understand about doing the final torque with the weight on the tires. When you put the weight on the tires the spring flattens out and you can then tighten the bolts further. Thanks for you suggestions
Melting Slicks
Joined: Aug 2001
Posts: 2,043
Likes: 1
From: Elkhorn WI
Re: Leaf Spring Help needed Bolts won't seat (eddadams)
I just replaced mine 3 weeks ago...VB 7 leaf..my old one was beyond flat.
I braced up each end, then was able to line up the locator and tighten my bolts...as said above...if anything, get a slightly shorter bolt, or you'll bust through the case... :nono: only hand tighten when on the jacks...
once you lower the car and load is set....then slid under and finish the tightening... :cheers:
I braced up each end, then was able to line up the locator and tighten my bolts...as said above...if anything, get a slightly shorter bolt, or you'll bust through the case... :nono: only hand tighten when on the jacks...
once you lower the car and load is set....then slid under and finish the tightening... :cheers:
Thread Starter
Instructor
Joined: Apr 2001
Posts: 178
Likes: 4
From: Hendersonville TN
Re: Leaf Spring Help needed Bolts won't seat (ylose)
Well I found the problem. My old spring is 9 leaf as is the new one but the old one has an extra metal strip about 5 inches long on the bottom side of the spring. The strip is not a full leaf. It only fits under the mounting plate. So there is the extra thickness. I called Vette Brakes and they said their spring is an exact fit. He said someone must have changed my spring and put in longer bolts. The car has only 50,000 miles so I highly doubt that the spring was switched and longer bolts added. So I have a few options, 1- cut the bolts to make them shorter, 2 - get new shorter bolts, 3 - take the plate off the old spring and put it on the new one. I think I am going to try cutting the bolts first. If that doesn't work I will get new bolts. I will keep the old spring intact in case I ever one it for restoration.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Le Mans Master
Joined: Sep 2000
Posts: 6,036
Likes: 2
From: Westfield Indiana
Cruise-In III Veteran
Cruise-In IV Veteran
Cruise-In V Veteran
Re: Leaf Spring Help needed Bolts won't seat (eddadams)
Well I found the problem. My old spring is 9 leaf as is the new one but the old one has an extra metal strip about 5 inches long on the bottom side of the spring. The strip is not a full leaf. It only fits under the mounting plate. So there is the extra thickness. I called Vette Brakes and they said their spring is an exact fit. He said someone must have changed my spring and put in longer bolts.
Burning Brakes
Joined: Nov 2001
Posts: 1,191
Likes: 1
Re: Leaf Spring Help needed Bolts won't seat (eddadams)
So I have a few options......2 - get new shorter bolts.....If that doesn't work I will get new bolts.
Drifting
Joined: Feb 2001
Posts: 1,603
Likes: 0
From: San Francisco, CA
Re: Leaf Spring Help needed Bolts won't seat (eddadams)
I had the same problem with a 7 leaf. The replacement was slightly thinner than the old 7 leaf which I am sure was original. So much for the exact fit theory!! I just threw a lock washer between the bolt head and the spring plate and that was enough to take up the slack. I know it is slightly Bubba-esk but effective and I have had no problems.
Instructor
Joined: Jul 2001
Posts: 118
Likes: 0
From: Bklyn,Ny U.S.A
Re: Leaf Spring Help needed Bolts won't seat (R. Bruno)
I replaced my 9 leaf a couple of months ago with a 9 leaf from mid-america had no problems putting it in.I also bought a kit from mid-america with it also it came with a new bottom plate and new bolts forgot how much it was but wasn`t too much also when putting in the spring I placed a jack under the center of the spring caught the 4 bolts then worked on the ends :seeya
Burning Brakes
Joined: Nov 2001
Posts: 1,191
Likes: 1
Re: Leaf Spring Help needed Bolts won't seat (R. Bruno)
I had the same problem with a 7 leaf. The replacement was slightly thinner than the old 7 leaf which I am sure was original....I just threw a lock washer between the bolt head and the spring plate and that was enough to take up the slack.
