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To clarify, drcook is talking about the #5 bushing in the diagram in post #4. Maybe that is the issue. I'd also verify that you have the correct front shock for your year C4. The problem you're having makes me think the shock is running out of travel in compression before it should.
Mr Miller - can you confirm how I can identify the RideTech shock to confirm that it is the correct model for my 1996 Corvette Coupe?
The shock bushings supplied with new shocks are wrong for our cars. The oem bushings had one that kind of looked like a mushroom and went through the hole inot the other shock, very much like the pin top bushings I posted a link to above.
Take a look at the detail drawing above. If the bushings don't have that step to fill the hole and go into the other bushing, the bushings will be able to punch through the shock tower hole.
Dr Cook - thank you for the feedback here, this is very illuminating. Do you know if installing the stock "mushroom-style" bushing with the RideTech setup is a possibility? I am considering reverting back to Bilsteins after having this issue now twice, but I would much prefer to rebuild with a more robust setup if possible.
A lot of those oem bushings have gone by the wayside over the years and there are no oem replacements that I could find. The closest is the pin top shock bushings I posted the links to above.
Pricey, yes, worth it ? A resounding yes. I put them on my car, once I got the nut tension adjusted correctly, what a difference it was! (my low mileage oem ones are stashed away, just in case). While I was swapping the shocks out (my car sat for a long time before I bought it, I am rebuilding it back to as new) I discovered about the bushings. Even the ones that ship with Bilsteins are wrong !
Sorry last night's post was a little muddy, I had just got back from the ER, I hurt myself and had a drug reaction.
You might try calling some of the Corvette recyclers and see if there is a low mileage wreck that has the oem bushings, but for a price to performance value, the mounts Banski sells have no equal. They let the shock work, not the bushings.,
Sorry last night's post was a little muddy, I had just got back from the ER, I hurt myself and had a drug reaction.
Ahhh, well that explains why you were writing about mushrooms...
FWIW, while I agree 100% that the correct upper bushings are important, I ran the incorrect-but-standard-issue bushings as shown in post #2 of this thread for years with no problems like vettes-n-effect is experiencing. It should take one hell of an impact to shove those incorrect bushings through the little hold in the upper shock tower.
Yes, this is exactly how the shocks were installed - and as you mentioned, the shock is breaking through the upper shock mount. You are not the first one to have asked the question, last year the folks at Ride Tech were surprised to see that the top retaining plate above the shock was ripped clean off.
I want to revisit this, along with your picture where you circle the problem area in red. I'm trying to visualize the order that washers and bushings were installed. What should be the case is that from bottom to top there is a washer (what you called retaining plate), then a bushing, then the shock mount sheet metal, then a bushing, then a washer, and then two nuts tightened together in a locking formation (reference the picture I posted). But what I think I'm seeing from the bottom up is a bushing, then a washer, with that bushing halfway through the hole in the shock mount sheet metal; then one nut, then the other nut about 15 threads away (i.e. not close to being locked), and then the wayward upper bushing, and a missing upper washer.
Something isn't computing for me: if the washer that we are seeing is indeed the lower washer (you said it's the upper that's missing), then the bottom bushing had to be installed below it. Are you sure you didn't mean that the lower washer was ripped clean off? If that's the case, then all the rest makes sense, because what's left if the upper wash and the upper bushing was pushed over it.
But even then, why aren't the two nuts locked together? If they weren't, and the lower nut backed off and let the shaft and bushings hammer around in there, then I might understand how a combination of that plus the wrong bushings led to this failure. Could you maybe take a pic of the other side so we can see how things were installed?
The holes through the shock tower on my 96 are over 3/4" in diameter. I will measure the actual part later today/tomorrow and post a picture. That is yardstick measurement. I will use dial calipers later.
I don't know about the earlier years C4's, but on mine, the smaller diameter ones, or ones without an interlocking boss, would poke through, or be cut to pieces relatively soon.
This is what the oem shock rubbers for a 96 look like. Notice the "mushroom" shape of the one that goes through the shock tower. At least on the '96's, if the bushings aren't right, they will poke through that hole eventually.
The "stem" is .930'ish. The through hole, .935 or so. The rubber compresses a little of course, even with the lightest touch on the dial calipers.
The Banski Pin Top shock bushings are shaped just like this. They fill the hole up and don't rattle around.
Go to the installation document on Banski's site and you will see the relationship better. I have added a screen shot of the document, but you really should go read it.
If you are having a shock rattle, this very well could be why. How about folks with other year C4's detail the size of the hole in the upper shock mount ?
If you are having a shock rattle, this very well could be why. How about folks with other year C4's detail the size of the hole in the upper shock mount ?
