Longer rear spring bolts...

[Ken]

The longer rear spring bolts that are used to lower the rear suspension height on a C4, "... have 4 inches of thread for adjustment that allows fine tuning of the rear suspension height."

My question is... How long are those bolts, and can I get them at a local hardware store or auto parts warehouse? What grade bolt is necessary?

I'm not going to drop the front, just the rear about an inch or so. I'm sure I can get the bolts locally, but I need to know the length. Anybody know?

 

[unleadedbrew]

Man, I'm glad you brought that up, Ken. I was going to warn you about the quality of bolt you get when you buy from Ecklers and I'm sure the other dealers are the same. These are very cheap made in China without even a rating on them. ad They're 10" long with 4" of thread. Try to find them somewhere else, if you can. I'm going to start looking myself, even I've already done it and had it aligned. I was hesitant when I first saw them, but hadn't heard of any one having problems so..............You'll also prolly get 'em a heck of a lot cheaper.

Gordon

 

[unleadedbrew]

Oh yeah, the rating on the stock metric bolts is 9.8. Pretty strong.

Gordon

 

[Ken]

:cool Ten inches is what I needed to know.

... just love my big 10 inch

record of her favorite blues

Thanks Gordon, I know just where to get 'em.

 

[Ken]

Gordon, I forgot to ask if you happen to know the bolt diameter; it'll save me the effort of crawling under there to measure it. :L

 

[unleadedbrew]

Gordon, I forgot to ask if you happen to know the bolt diameter; it'll save me the effort of crawling under there to measure it. :L

The OD is 1/2" with whatever metric is close to a 13/16" head. I used a 13/16
box end on the head and a French "croissant" wrench on the nut. Since the new bolts don't have the hole drilled for a cotter pin, they came with a locking nut.

Gordon

 

[Ken]

Thanks Gordon.

 

[Vettelt193]

Think you can get them at a local home supply store (like Home Depot or Lowes)?

 

[Ken]

I've got a guy locally - The Boltman! :cool

 

[unleadedbrew]

I've got a guy locally - The Boltman! :cool

First there's 'Bruce the Brush' and now the 'Boltman'...........Sounds like a bunch of "B" rated super heros you have there, Ken.

 

[Ken]

Hey, I didn't name them - they named themselves. :L

 

[JT ZR-Won]

Ken, I installed the Mid-America bolts on mine but they weren't long enough to lower the car where I wanted it. I had custom bolts made that were longer and very heavy duty on my ZR-1. If you can get 'em longer I would.

Jay

 

[c3guy]

I have done this type of thing long before it was popular, and I would use a grade 8 SAE bolt which equals 10.9 metric. The 8.8 metric that you are talking about is only equivalent to a grade 5 SAE. A Grade 9 SAE bolt is more brittle as I understand, compared to a grade 8 that will bend under the most severe load, as opposed to a grade 9 that has more shear strength but can snap. I used to buy all my grade 8 and grade 9 bolts from a local truck center at night, and had the no invoice pricing of "aww just take them and get out of here". Their inventory must have been a mess!!!!!!

 

[Ken]

Well, just like everything else I try to do, I can't get it right the first time.

I stopped by the bolt store and found a bolt to match, in Grade 8 nonetheless, but it only had about an inch and a half of threaded portion. Of course, I guess I could always cut more threads if necessary...

Jay, you say you used longer bolts than ten inches? How long exactly and how low did you go? :confused

 

[JT ZR-Won]

Ken, I also used the bolts on my '85 and it lowered the rear to the perfect height. For some reason, when lowering my ZR-1 it just didn't lower the car that much and my driver side was practically out of threads. I had a little bit left on the passenger side though. So I ditched the bolts and got longer ones. The ride height was perfect after that

 

[WhalePirot]

9 1/2" from Dick

Guldstrand sold me my bolts, long ago. They included a Nylock nut and are 1/2". I recall using #8 hardness bolts on my '71.

My half-shafts are straight across, as they should be.

Ken, you saw how low my car is. My 335x17's modify the inner wheel wells on large dips.

 

[Ken]

So, you guys are telling me that I do not need the full four inches of thread?

 

[WhalePirot]

I have about 1/4" to 1/2" of thread showing, below the Nylock nut. It rests on a urethane bushing atop the washer.

 

[Ken]

Which brings up another point - I guess I should replace the bushings in there while the bolt's out. Where'd you get those, did you use the stock rubber replacements you got at the dealer, or did y'all use aftermarket polyurethane or something similar? :confused

 

[WhalePirot]

I am not sure the urethane makes any diference on this. The car rests upon it, and it is not a push-pull situation, as in other suspension areas, where rubber flex would allow play and looseness.