Rear Spring Bolt Length

[Maymyvetteliveforever]

I've read in Vansteel's site that the stock bolt is 6", I see in Keen's site that it's 6 3/8". Then I've seen some say that it's 8" what is the correct stock length of rear spring bolt for a 75' Coupe?

Next question is the thickness, I've read between 1/2" and 9/16" what's correct?

Next question, on Vansteel's site they show in the picture below that the kit includes two bushing per side, I thought it was 4 per side, maybe mine are crushed so much that I thought it was 4?


SG-11P8K

 

[MYBAD79]

6" or 6 3/8" won't make a huge difference. Why do you ask, do you want the 'correct' bolt or do you want to adjust the ride height to where it needs to be ?

My advice? Buy the kit with 8" bolts and new washers, cups and bushings. Rubber bushings are fine but Poly is just as good and supposed to last longer....

Run the nut up so that the ride height is correct - drive the car so the suspension can settle, just letting it off the jack won't be enough, it will settle after you drive it over a few bumps....

Once the ride height is ok, cut the excess of the bolt under the nut off, these 8" bolts have enough thread for adjustment, you'll likely end up with a 7" bolt.

I think stock size is 1/2", I am using 9" long 5/8" grade 8 bolts from McMastercarr.com - with these 9" bolts I have about 1 1/2" excess under the nut, still need to cut it off ... if I ever get a flat tire the bolt will drag on the road if I don't cut it...

 

[Maymyvetteliveforever]

Thanks for the reply MYBAD79.

Reason I ask is because I presently have 6.5" bolts but my second set of 9 leaf metal seems to be sagging a bit. I was thinking of keeping the 6.5" for now untill I can't the rear leaf and tires and wanted to go back to stock size bolt.

When you mention getting the grade 8 bolt from McMastercarr.com, where did you get the bushings and washers from. I wasn't aware they were sold seperately?

Are there 2 rubber bushings per side?

 

[Twin_Turbo]

Yes, only 2 per side.

 

[red74]

I prefer the OEM 6" bolts and rubber cushions.

 

[Maymyvetteliveforever]

Yes, only 2 per side.

Thanks TT.

I prefer the OEM 6" bolts and rubber cushions.

So you're say that OEM stock is 6" Bolts?

 

[SmokinBBC]

The stock bolts off of my 70 are 6 3/8.

 

[MYBAD79]

When you mention getting the grade 8 bolt from McMastercarr.com, where did you get the bushings and washers from. I wasn't aware they were sold seperately?

Are there 2 rubber bushings per side?

I bought a kit with stock length bolts and found they're too short. Then I bought the longer bolts from McMaster.

I prefer the OEM 6" bolts and rubber cushions.

I prefer a shorter bolt as well but ride height and half shaft angle is more important to me.

 

[mrvette]

When you mention getting the grade 8 bolt from McMastercarr.com, where did you get the bushings and washers from. I wasn't aware they were sold seperately?

Are there 2 rubber bushings per side?

I bought a kit with stock length bolts and found they're too short. Then I bought the longer bolts from McMaster.

I prefer the OEM 6" bolts and rubber cushions.

I prefer a shorter bolt as well but ride height and half shaft angle is more important to me.

when going VBP plastic, I noted the increases bolt length, but with 17" wheels, it's not a problem, I also have not lowered the car any, the prime reason is about ground clearance, I hate dragging ass or front 'spoilers'.....it IS a street machine, after all.....

:surrender:

 

[vette78SA]

Rear leaf spring bolt kit etc?

I am thinking about replacing the rear leaf spring bolts etc on my 78SA. The spring is probably OE and still seems to ride okay. The current bolts are 8" in length and the grommets etc look pretty worn out.

Is there any way I can just R/R the bolts, grommets etc on each side without fussing with the spring? It looks like I can block the end of the spring on each
side with a chock and just replace the hardware. Is this the proper way to do
it?

In advance, thanx for your input, tips and suggestions.

vette78SA

mike

I've read in Vansteel's site that the stock bolt is 6", I see in Keen's site that it's 6 3/8". Then I've seen some say that it's 8" what is the correct stock length of rear spring bolt for a 75' Coupe?

Next question is the thickness, I've read between 1/2" and 9/16" what's correct?

Next question, on Vansteel's site they show in the picture below that the kit includes two bushing per side, I thought it was 4 per side, maybe mine are crushed so much that I thought it was 4?


SG-11P8K

 

[MYBAD79]

Put a C-clamp on the spring to prevent the jack from sliding and place the jack under the spring end. Jack up the spring until you took the load of the bolt (cushions will be loose now) and remove the nut and then the bolt... replace bolt/nut/cushions and lower the jack, remove C-clamp and move on to the other side.... easy....

 

[010752]

The oem bolts on my 75 convertable are 6" long from the underside of the head. Maybe they got the 6 3/8" including the head.:smash:

The first 1/2" or so under the head is 9/16", then the majority of the shank is 1/2" and then the threaded area is back out to 9/16" unf. A special bolt.

Grade 8, 1/2" or 9/16" bolts are availavle at any Ace Hardware in 1" increments. Either will work just fine.

To replace, just put a block of wood under the end of the spring, clamp a vicegrip unto the spring to prevent sliding and jack up enough to release the original bolt tension.