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Another rear spring issue!

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Old May 10, 2010 | 01:29 PM
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Default Another rear spring issue!

My '76 has a very stiff rear spring. It's like driving a truck. I had a '75 before, and it was not nearly as rough a ride. I have a 9 leaf, 2 1/2" wide spring, with 9/16" bolts. So it is the 78-82 size. Pushing down hard on the rear fender, I barely get 1" of deflection. My wheel opening centerline is 29 3/4" high, so it seems to be about 2" high. (with 8" bolts). I want to replace it with a 78-82 style VBP composite 300# spring kit, with 8" bolts. Will this cure my problem? I know everyone seems to favor the stiffer springs, but I just want a smooth ride to go cruising.
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Old May 10, 2010 | 01:38 PM
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First of all. The 9/16 bolts are the 63-77 type. (78/79 use 7/16 bolts.) So in your case your '76 indeed has a '76 spring and bolts.

Now that you have that part straight.. Call Andrew at Muskegon Brakes and ask him about his 300# 2 1/2 inch composite spring kit.

And make sure you mate that 300# spring to fairly wimpy shocks if you want a softer ride. ie Billstein Sports will still make it feel "harsh" by comparison to cheaper shocks.

Andrew
1-800-442-0335 Unbelievable Service!!

-W

Last edited by Clams Canino; May 10, 2010 at 01:41 PM.
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Old May 10, 2010 | 02:07 PM
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Thanks CC. I replaced the shocks last year with Delco gas shocks, hoping they would ease the ride. They should be fine with the 300# spring.
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Old May 10, 2010 | 04:04 PM
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I just double checked my rear spring/diff cover. As I said, the spring is 2 1/2" wide. The attaching bolts have a 9/16" head, and a 7/16" bolt dia. In addition, the casting number on the diff cover is 464910. I looked up some spring selection info, there it states that the 63-77 bolts had a 13/16" head, and the 78-79 bolts had a 5/8" head. It can't be a 63-77 spring, since it's 2 1/2" wide. Can anyone shed some light on this??
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Old May 10, 2010 | 04:17 PM
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Yes... I misunderstood your 1st post. A bolt size is not usually refered to by "head size".

So.... you do have the 7/16 bolts. That means you DO need the 78/79 spring.
You have the same issue my 1968 had - I just did this.

The Muskegon number is 600-107 315lb spring.
-W
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Old May 10, 2010 | 04:29 PM
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Thanks again CC.
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Old May 11, 2010 | 09:04 AM
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Originally Posted by Clams Canino
First of all. The 9/16 bolts are the 63-77 type. (78/79 use 7/16 bolts.) So in your case your '76 indeed has a '76 spring and bolts.

Now that you have that part straight.. Call Andrew at Muskegon Brakes and ask him about his 300# 2 1/2 inch composite spring kit.

And make sure you mate that 300# spring to fairly wimpy shocks if you want a softer ride. ie Billstein Sports will still make it feel "harsh" by comparison to cheaper shocks.

-W
Thanks for the mention, I really appreciate it! And I am definitely happy to answer any questions.

Andrew
800-442-0335
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Old May 11, 2010 | 01:08 PM
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If you're after ride quality what you want is the Hyperco "Easy Ride" 200 lb spring:


http://cmc.speeddirect.com/itemdesc....413HPS&eq=&Tp=
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