Hi all! This is my first post here. I just bought a 94 and was determined to fix (or at least reduce) the body flex. I've driven a few vettes in the past (c3, c4, c5 and c6) so the flex was nothing new or surprising to me. It's always seemed to me that they don't exibit this flexing until the miles or age start getting up there. The vette I bought has 151,387 miles on it and is 18 years old, so it had it's fair share of flexing going on.

I started by checking all the suspension bushings, ball joints, tie rod ends, wheel bearings, ect. No problems there. Everything was tight, most components were new from the previous owner. The previous owner also installed a front suspension cross brace...still flexed.

After studying the "structure" of the "frame", it became very apparent to me that the frame is made up of many brackets, braces and sections. All of these components bolt together to create a larger "frame structure".

So this is what I did....

I simply tightened every bolt I could find that was holding the "frame structure" together. I tightened everything in the front and rear along with all suspension bushing bolts. There are alot! I didn't count them, but I would guess I tightened at least 75 bolts/nuts in all.

It made a night and day differance! The car handles much better, took care of a front end shimmy that was occuring at about 30mph, car feels much more solid, responsive and just plain tighter!

I did put the car on a lift to do this. It would be hard to do on the ground or on stands because the bolts are big, hard to get to and require big wrenches to tighten them up good.

About 40% of the bolts were loose.

 

Interesting, but very believable.

 

That is interesting ... I guess I never looked at this. Did you take any pics?

 

The only thing I would have done different(perhaps you did) is remove the bolts, clean up the thread, and thread-lock them back in. With them aging I wouldn't want to push my luck having to tighten them a second time and breaking heads off.

 

Sorry, I did not take pics. The loose bolts were not so loose that they had backed out or anything, they were just not very tight.

I would say they were about as tight as a transmission pan gasket bolt, when they should be about as tight as a lug nut.

Most bolts I could only tighten about 1/4 turn. About a dozen of them took 1/2 turn and probably another dozen bolts took 3/4 turn to tighten them up.

I own a small auto repair shop in Zimmerman, MN. If there is a member here that lives close by, I would love to do this for them just to get someone elses opinion on how it changed the ride/handeling quality of the car.

 

There is a torque spec for all the bolts on the car as outlined in the factory service manual. Did you torque the bolts or just tighten with the "big wrench"?

 

That makes good sense. A lot more than the $500 longitudinal braces that were trying to be sold.

 

That makes good sense. A lot more than the $500 longitudinal braces that were trying to be sold.

 

I've heard good things about them, but I just can't bring myself to spend $500 on a pair of steel rods.

 

Here is an example of C4 frame stiffness.

 

Yes, all cars and trucks (not just corvettes) have a torque spec for every bolt. I found this out over the last 20+ years of being a mechanic. I believe there is even a section in the ASE master certification test that I take every few years.

By "big wrench", I was refering to the 24mm wrench needed to tighten some of the bigger bolts.

Does your wrench set go over 18mm? Mine goes up to 36mm. Do you know what a mm is?

 

Hey, no need to get testy. I just asked if you torqued the bolts. I wasn't attacking you. Congratulations to you for having a big wrench. That must make you a big man.

 

pm sent

 

 

PM replied to (same or next day, just hadn't updated this thread yet). Hopefully 94vettelover2 and I can get together sometime and try this out on his car. I would love to get a second opinion on how this works. Maybe I'm feeling a difference that isn't really there? Maybe I'm feeling it because I WANT to? I kind of doubt it though, because the more I drive it, the tighter it feels to me.

94vettelover2, you have my number so just give me a call when you think it might work for you. My zip is 55398, so you can get a general idea of driving time and distance.

First one is free just so I can get some feedback on how this works.


Sorry, I did come off a little testy there. I took your words as sarcasm...my bad.

No, I did not torque the bolts with a torque wrench. When you've been loosening and tightening bolts as long as I have, you find that there are only a few different bolts that NEED to be PRECIESELY torqued...like head bolts, mains, rods, manifolds, rockers, internal engine/transmission/differential parts, ect, ect.

The general rule when you do this work all day every day is: you go by the bolt size to determine its tightening torque. If the bolt holds two surfaces together that have a gasket in between, then you need to torque it. If the bolt holds two metal brackets together with no sealing gasket, then the torque is a lot less critical...still needs to be tight though. You could say that I have a "calibrated arm" when it comes to most fasteners. Certain applications still require a torque wrench, but not for this particular job.

 

Cool

 

This is the BEST solution I have seen about our C4s which are accumulating miles.

I am sure you are not imagining the tightness in the feel of your Vette.

After all, you would know better than anyone.

I, too, can tighten bolts like you after being in the business for over forty (40) years.

Congratulations on a great fix!

 

I think the reason 383vett brought up the torque specs is because many of the bolts that secure the C4 frame and frame braces have torque specs in the 30s and 40s....far less than the 100 used for lug nuts.

 

my wrench set goes to 36mm! do i get a prize?