Suspension/Driveline problems

[WCFB-Russ]

(Note: Placed this in the main suspension forum as well because not everyone checks the 4th generation forums and i really need as much insight on this problem as I can get)

So --- get a soda and some snacks cause I gotta run down the story really quick here and it might take a little bit:

Back in 2005 - driving my 1994 Camaro 3.4L V6 after having broken in the Spec Stage 2 Clutch and installed a Polyurethane Trans Mount to my 5-speed manual (t5) - I happened to be on the 110N freeway heading onto the 91W. The interchange there is a fun dip to a 90* turn on which I *always* down-shift, hit the apex and floor it out of the turn just for s&g.

On this particular occasion I did the same as I had always done, and upon hitting third gear an flooring the accelerator - I hear an *extremely* loud BANG (almost a BAM noise) and suddenly the entire car is shaking. I was probably going above 75-80mph when it happened...

I pulled to the side of the road, convinced I had blown a tire (that's what it felt/sounded like) - made sure it was safe, got out of the car and did a complete walk around. No issues. All 4 tires were inflated with no signs of distress, bulges or damage/wear. So I get back in the car and accelerate back up again, to find the vibrations around 60-65 mph. We (my wife and I) were headed to a friends house, so we got there and since he was a car guy, we talked the matter over with him, deduced it was probably the U-joints giving way, and I resolved to fix them.

Did that. Bought two new u-joints and melted the old nylon out of the factory ones on my Ls1 STEEL driveshaft and replaced the U-Joints with Spicer U-Joints I bought from pepboys.

Vibration seemed gone, until I hit 70-75mph - I tried pushing past the vibration but it seemed like the faster I went the worse the vibration got. Never did manage to find a place where the vibration vanished, and I have been on a quest to eliminate since.

Without making this story too much longer, to date I have:

• Replaced Axle Bearings/Carrier Bearings
• Replaced rear with LS1 Rear End (3.42 gearing / full disc - after causing the pinion to grenade - long story)
• Replaced Rear Tires
• Replaced both Front Wheel Bearing Hub Assembly
• Replaced both Outer Tie Rod Ends
• Replaced Front and Rear endlinks
• Replaced U-Joints
• Had driveshaft rebalanced
• Replaced transmission (another long story)
• Adjusted transmission mount height to bring to proper height w/poly endlink pieces

I cant adjust my pinion angle because I have a TQ arm made by MAC which JEGS now sells, looks like this:


(kind of auto-adjusting).

As of right now if I get the car up to 3500 rpm in 4th gear (about 80mph) or above 2500 rpm in 5th (around 80mph), the entire car vibrates. Vibration is felt in the pedals and the middle-back of the driver's/passenger seats.

Anyway - would appreciate any info anyone can give me or suggestions. I'm sure I've replaced more parts on the car but those are the only pieces I can think of. If you mention something and I've replaced it I will definitely add it to the list of replaced/repaired parts.

Also - in 2005 I had my entire steering system rebuilt and replaced the stock v6 rack with a Z/28 steering rack - however it does *not* look like they replaced the steering components other than the rack itself, and I'm a little concerned about that...(rubber on the outer tie rods was 1994 original and very rotted/falling off when i replaced them).

Thanks for any help you can give.

-Russ

[White_Knuckle_Tight]

Gremlins...haha, I dunno man, but now I am really curious as to what it is. The loud bang has me stumped. Maybe something broke internally? I have no idea man

[hypurone]

First thing that comes to mind is shocks/struts. Even if everything is balanced, the road is not as smooth as you think it is when it feels smooth. At speed when a small oscillation is started in the suspension, it will only intensify if the shock/strut can't dampen it...

If those have been changed/upgraded, I would be looking at the rear suspension bushings (trailing arms, diff mounts etc) as well as the engine and trans mounts....

[02pewtersix]

check shocks/struts. all bolts bolted in and tight holding the T/A brace to the tunnel? how about the shaft that the torque arm slides on, is it binding? how about the bolts that slide into the back of the torque arm that bolt to the rear end. be sure those are tight
check lower control arm bushings and anything on suspension before you tighten and torque be sure the suspension is loaded.

[WCFB-Russ]

brace is tight, not binding (checked when i changed the clutch just last month).

Shocks are something I haven't really thought about -- I guess something I should add is that this is the first full year that she's seen road action. Normally I only drive her for a few months and as such -- have kind of neglected replacing certain parts.

The bushings/shocks/hoses are all "vintage" '94. (working on replacing them as I go..I've got a checklist)

That being said, I'll push the shocks/struts to the top of the list. I've also been told to remove the "isolator" plate from the poly trans mount, to replace the steel DS for an aluminum one -- but the bushings / shocks are something that I haven't really put much emphasis on.

Thanks for all the good suggestions from everyone.

[White_Knuckle_Tight]

Actually come to think of it, if it isn't your shocks, then I'd check the engine/ tranny mounts. I had an old '75 Chevelle Malibu that did something similar to this when I first got it. It would vibrate and make hellacious noise at higher speeds but not at lower speeds. It ended being a combination of worn out suspension not being able to "soften" road bumps, and a broken engine mount.

[WCFB-Russ]

I doubt it's the engine mounts but it is something that I've taken into account at one point or another and I will take it under advisement. Changing out the poly trans mount to a stock trans mount has been suggested, in addition to removing the "isolator plate" on the poly tranny mount, suggesting that the poly trans mount vibrates waaaay too much either with the plate on or just in general. I'll start with the mount and work my way out (I am looking at shock options atm. though).

Thanks everyone

[02pewtersix]

it is not advised to take the plate out..(if you are refering to the plate that sits between the trans and trans mount. that is there to help compress the trans mount and equalize pressure and allow for a constant flat surface for the mount to rest on when bolted in

[White_Knuckle_Tight]

Oh your welcome by the way for pushing this back to the top so everyone notices it, LOL

[WCFB-Russ]

Originally Posted by White_Knuckle_Tight

Oh your welcome by the way for pushing this back to the top so everyone notices it, LOL

;-) lol