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If I hit a "rare" NY pothole my rear will bottom out. It is not lowered and has good travel to me.It does take a good shot too bottom out. I have multileafs w/poly bushings. I installed shocks years ago but they have no miles. They are black but I don't remember what brand. If I push the car down from the rear it is like a rock.I was thinking of shaving the bumpstops for extra room or is this a mistake? Somone told me to get old style shocks.Any advise will be great. I can take pics or measurements if necessary. Thanks. Brian.
 

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If you feel the rear axle is hitting against the bumpers, take two styrofoam cups and duct tape one per bumper.

Go for a ride. Check to see if cups are touched/smashed. If not, then shocks are too hard.
 

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That's what bumpstops are for the big potholes/bumps. They are tapered so a small hit won't be harsh but if you trim them they will be more agressive when you do hit them. If the pinion angle is high, there is a bumper over the pinion nose that can hit too.

Better shocks might help but I hear the popular KYB's are harsh riding. Bilsteins are good.
David
 

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Just got back from Huston Tx on business. I saw a 200 car cruise night w/ nice 1st gens thanks to Danny Vee w/ the Huston F body club on the board.Nice guy.
Everett, good idea. I was going to put white grease on the stops.
David, you're right I won't cut them. Please explain to a suspention lamon.
"If the pinion angle is high, there is a bumper over the pinion nose that can hit too." Can I adjust anything?
If I look close is there a chance the shocks are marked so i can see what I put in there? If I disconnect the shocks @ the bottom and push the rear down should there be a difference?

Thanks guys, after reading many of both of your posts I know I am typing to
very knoledgeable Camaro people. Brian
 

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No adjustment on the pinion snubber. It is merely a bumper to prevent the pinion yoke from hitting the floorboard.

If you disconnect the shocks, the rear body should move easier by hand, but you will never bottom it out, you're too light. Add some weight, a few bags of Quikrete/sand, then the rear body will move and it should oscilliate some without shocks.

Also, too much air in the tires will stiffen the tires and give a rough ride. Any tire pressure over 34(?) PSIG will stiffen the sidewalls rendering them useless to absorb, read bend, with road terrain.
 

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That's what bumpstops are for the big potholes/bumps. They are tapered so a small hit won't be harsh but if you trim them they will be more agressive when you do hit them. If the pinion angle is high, there is a bumper over the pinion nose that can hit too.

Better shocks might help but I hear the popular KYB's are harsh riding. Bilsteins are good.
David
Dave, that is the way I understand it – the shape almost makes the spring progressive, sort of. That thought leads me to believe fixed poly bump stops are a bad idea - no deflection. I will not be using the poly ones that came with my TVS kit. I have a like new OE rubber set off a 3rd gen that are the same height as the stock 77 Z28 bumps (including the aluminum spacer block). I’ll start with those.

Wasted stock 77 Z28 bump, 3rd gen WS6 bump.


Marcus (SC&C) turned us on to these bump stops. Appear to be poly, but not fixed like the Hotchkis ones (likely made by energy suspension). These would be my next move.
Shane73 at NastyZ28 said:
The GM PN is 15956547. Application if needed would be a 2000 S10 Extreme/ZQ8 package. With a 1" lowered ride height typical on our cars, there should be about 1/4"-1/2" gap between the frame and tip of bumper. I was also told that the first 3/4" of travel in these bumpstops can be compressed by hand….They are supposedly a "progressive" bumper. They also rebound slower than the suspension movement so there is supposedly no "rebound" effect to them. He said you can even run the bumpstops touching at ride height with no ill affects.
Link: http://home.earthlink.net/~igraves96/sitebuildercontent/sitebuilderpictures/zq8s2.jpg

Mr. Pozzi, am I in line with my thoughts on fixed poly bump stops? Or am I reading too much into it?
 

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Just got back from Huston Tx on business. I saw a 200 car cruise night w/ nice 1st gens thanks to Danny Vee w/ the Huston F body club on the board.Nice guy.
Everett, good idea. I was going to put white grease on the stops.
David, you're right I won't cut them. Please explain to a suspention lamon.
"If the pinion angle is high, there is a bumper over the pinion nose that can hit too." Can I adjust anything?
If I look close is there a chance the shocks are marked so i can see what I put in there? If I disconnect the shocks @ the bottom and push the rear down should there be a difference?

Thanks guys, after reading many of both of your posts I know I am typing to
very knoledgeable Camaro people. Brian
The pinion angle is adjusted by using shims between the axle and leaf spring. There are special wedges made of aluminum. You don't want to adjust pinion angle without taking some careful measurements, the driveshaft angle is critical or you will have vibrations.

Take a look at the rear bumpstops and also where they contact the rear axle. See how much gap there is and if the rear axle looks like the bump stop has been hitting it a lot. If it has, the axle will be shiny and the bumpstop will be darker in the contact area.

The rear shocks usually have a steel cover so the shaft can't be seen. If it can be seen, then get a small nylon tie-wrap and put it on the shock shaft. It will get pushed up by the shock to indicate shock travel.

Scott.
I'm not sure what the Hotchkis bumpstop you mentioned looks like. Our 73 Camaro has them but they are cone shaped and that's progressive but a bit stiffer than stock.

The bumpstops in your photo are like the Third Gen bumpstops but the IROC I had in 89 had steel in the lower "step". It was bonded into the rubber but you could feel it in there. They were pretty harsh once the tall part compressed down to the lower step.

I'd use the progressive bumpstops in the photo if the alternative is a rectangular lump.
David
 

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Thanks Dave. Those sound like the same ones Hotchkis included, kind of shaped like bullets - they seem hard as a rock. I was thinking they aren't too progressive if they are so hard. I'll have to compare height too. They didn't look too short

I'll check those stops I have and see if they are like the IROC ones you described, with the step. They are from a low mileage 1985 WS6 16" wheel Trans Am I stripped some years back. Also the donor for my steering box.
 

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Dave, you were right. There feels like there is steel going across midway up, where the 'bump' protrudes from that 'shelf' like flat part. The TVS stop comes to that 'shelf', so about 1/2 the height. I'll use those for now.
 

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Discussion Starter #11
David,
I should have asked you this and looked @ my rear housing before painting it. Duh. I think the bumpstops themselves did not look bad. If I put the tie wrap on the shock shaft will I be to see if it is bottoming out? Can a shock be too short? Naaaa.Super thanks. Brian
 

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Scott.
When I'd brake our IROC very hard, one front wheel would allways lock. I thought that was strange because the brakes felt great. I figured out the front would bottom and hit the hard part of the stop, then lock a wheel due to the sudden weight transfer. I wanted to fix it but the SCCA autocross rules didn't allow it, so we had to brake more gently.

Car nut,
check the shock travel and clearance from housing to bump stop and see how much potential travel you have.
David
 

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Wow. Some of the local guys who autoX said they have taken them out from time to time as the sudden hit is rather jarring.

If size/design equal, is it safe to assume a poly stop is 'less progressive' then a rubber one, and realistically would it make any real difference to the driver?
 

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Wow. Some of the local guys who autoX said they have taken them out from time to time as the sudden hit is rather jarring.

If size/design equal, is it safe to assume a poly stop is 'less progressive' then a rubber one, and realistically would it make any real difference to the driver?
A guy running locally might get away with removing them, but we ran at the nationals and there was over 50 cars in our class. Many of them were camaros and we didn't want to do well then get protested. A corvette driver won and got protested over his steering wheel which was 1/2" too small! they took away his win.

I'd say poly is stiffer compared to the stock bumpstops.
David
 

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I agree,poly is generally harder durometer than factory rubber. Also many of them seem to give no thought at all to the shape/progressive rate. The ZQ8 S10 ones mentioned above are NOT poly,they`re a spongy orange cellulose elastomer of some kind. You`ll fine the same type of material used on almost all new cars and trucks. The 1st Design version looks very much like the WS6 stops shown in the pics above and has a very smooth progressive rate. You can`t even feel it when they touch. In the factory application they`re only about 1/4"-1/2" from touching the frame at ride height and they work very well like this. Nice soft,controled ride. The other neat thing is that they rebound much more slowly than rubber so they contribute almost nothing to the rebound rate of the car. For about $9ea. from GM Parts Direct give em a try. I have them on several cars in the front and we have a few clients who tell us they work very nicely in the rear also. Mark SC&C
 

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Anyone have a picture of where the rear bump stops go?
 
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