tuband

I just had my rear suspension off last week in order to change the gears. I lowered my rear over a year ago and used grade 8 bolts & nyloc nuts obtained from a nuts & bolts distributor. I did cross drill the ends of the bolts for cotter pins in order to have additional security. And I'm glad I did.

Here's why ..... the nyloc nuts are no longer staying tight to the threads of the bolt, especially in the location where they should be. That's of little concern to me since I have the cotter pins on the ends but it does mean that something has caused the nuts & bolts to "loosen" slightly so that they can be turned by hand. I don't know whether is is "normal" wear & tear or if cross drilling the bolt produced enough heat to change the characteristics of the bolt.

But if anyone has done a total DIY lowering mod, you might want to check your nuts (whoa, that doesn't sound good, does it?) Seriously, I would hate for someone to drop their suspension when they least expected it.

Needless to say, I'm probably going to replace the nuts & bolts very soon. But I would like to solve this issue before doing so.

FoolCrzy

:eek:

chucks88

I've got the VBP lowering kit but i'm, gonna mark the position of the nuts on the bolts for sure :thumbs: Good heads-up :yesnod:

Rob90

Thanks for the heads up. Lowering the rear is my next mod

VetteNoob

Thanks for the alert! What size bolt did you use and how long was it?

tuband

From memory .... I think I used 5/8" fine thread approx. 10" long. I measured the old bolt and got the closest thing to the diameter and about 2 inches longer. Definitely get fine threads and make sure it is Grade 8 hardness. Also you should use nyloc or similar nuts.

Hey, I like your sig. How did you do the rotating thing on the left?

VetNutJim

Anybody using the jelly method of securing those fasteners?

I mean using a second nut as a "jam nut"?
I'm thinking of drilling mine but may prefer the jam nut method.

vetracer

Why not use the OEM nut with a longer bolt and just drill a hole further down the bolt the same distance that you want to lower the car? For example, if you wanted to lower the car 1", offset the hole in the bolt down 1". That way, when the cotter pin is reinserted the bolt can not turn at all, just like the original setup.

Rob 93ZR-1

That's so simple, even I can do that. Thanks. :)

65Z01

Thanks for the heads up; guess I'll check mine soon as the snow melts.

The jam nut sounds good.

Coupe89

I used Locktite red with lock nuts, on my rear suspension.
No problems yet :skep: I'll keep checking...



[Modified by Coupe89, 11:18 PM 2/19/2003]

tuband

This sounds like a good idea ... easy, too.

RichK

I asked some friends on another forum (land racing) because I feel the nyloc locknuts are being misused in this installation. Here's a response that bears out my thoughts (plus a little history).

RESPONSE:
"Nyloc" is a trade name for one vendor's "prevailing torque locknut" but
there are others. Esna is one manufacturer that makes them. When those
locknuts first came out around WW II, the insert was made of a tough fiber.
Later, the material was switched to nylon. The idea behind the nylon insert
is to assist in keeping the nut from spinning off the bolt under vibration.
The primary locking mechanism was tightening the nut on a bolt to its
specified torque; the "prevailing torque locknut" simply added a measure of
additional safety. The nut's locking mechanism was NOT intended to provide
adequate safety by itself!

For locknuts to be effective, the nylon insert needs to be accurately sized
and of the proper grade of nylon. In addition, the bolt pitch diameter must
be correct and the thread profile needs to be in spec. Commercial hardware
doesn't have the standards that aerospace and MIL-spec hardware does. The
quality control of some commercial hardware is so pitiful that I've seen
nuts and even bolt without any threads.

There are all-metal "prevailing torque locknuts" that are used in areas
where the temperature is too high for nylon types. Generally, they have
higher torque but I wouldn't rely on this type of nut alone, either. Loctite
helps but you can't beat a cotter pin or safety wire.

Carol Smith's books address this question very well.
END RESPONSE:

The key is "prevailing torque"; when the rear rises you could unload the bolt. The only resistance to the nut turning is the interference fit between the nylon and bolt. It was never distorted enough when tightened because it had nothing to "bottom" against. I like the idea of the original nut with a longer bolt and a new hole for the cotter pin.

RichK

Lone Ranger

My doctor told me this same thing recently, as we discussed fact that I turn 40 soon... :rofl:

h rocks

I think you got either an undersized bolt, a bolt or nut with poor thread geometry, or sloppy locknut insert. The elastic stop nut material might be defective. In any event, I have run them on mine for 5-6 years without issue.


[Modified by h rocks, 10:09 PM 2/20/2003]

BANDOBOY

FYI... There are many types of locking nuts to use. A "Nylock" is probably the most useless type in my opinion. I would use a k-lock nut which is a nut that is distorted on three sides to make the threads have three high points. As the nut is tightened, the threads conform to the root diameter of the bolt. I would double nut to be safe. A spring washer could be put in between the nuts to make the application even better. locktite always gets the job done for me as well. They sell nuts with a patch already applied to the threads.

gtsyellow

double jam nut seems to be the easy idea here. grade 8 bolts aren't easy to drill through. even harder is doing it without mangling the threads

tuband

I knew that if I posted this that the Forum members would come through with good ideas, suggestions, etc. Once again, I stand in awe at the knowledge available here. Thanks to all who have posted.

tuband

CentralCoaster

Thanks for the details! I hadn't thought of the unloading.. etc. Is it possible that you melted the nylon enough to relieve its friction to the bolt when you drilled the bolt?

For this application, fine threads will keep the nut on more securely. Double-nutting is a great idea, because its easy, and preloads both nuts.



[Modified by CentralCoaster, 10:23 PM 2/20/2003]

Darkness

Good heads up! :thumbs: