New KYB's! Rear End is still bouncy?

a_alyte · 06-27-2007, 12:58 PM

I now have new KYB's all around & I have noticed a difference, especially in the front however, the rear end still feels too bouncy. When I push down on the front end there is very little bounce (the car comes back up & thats it), when I push down on the rear, the car comes back up, back down & up again (very little resistance as compared to the front)! The rear end also feels too bouncy when traveling over dips at highway speeds.

I had the front struts installed at one shop & the rear installed at another, not sure if that matters.
Should I replace the springs next or is there something else I could check?

Thanks

richtazz · 06-28-2007, 06:05 AM

If you didn't change the rear upper strut mounts, that's probably where the bounce is coming from. KYB is a quality unit, but it's not impossible that you got bad ones wright out of the box either.

BNaylor · 06-29-2007, 07:23 AM

How many miles were on your GP when new struts were installed. With KYBs the rear end may have some bounce compared to stock but not too bouncy where you cannot live with it. It may take time to settle in. If not I would look at the possibility of weak strut springs. With springs removed the spring height can be checked to see if in factory specs.

a_alyte · 06-29-2007, 12:18 PM

I just had the KYB's installed at 134K miles. I did not change the mounts because the ones I ordered from Tire Rack (also KYB) looked a bit different from the originals, & the mechanic thought they might cause noise. The KYB mounts had numerous holes where the originals only had 3 (it still lined up however), & the KYB mounts once fitted on top of the struts showed more play than the originals. Does this sound right or did Tire Rack send me the wrong mounts?

Also, if I go with Eibach Pro-Kit Lowering Springs, would an alignment be all that I need to bring the car back into specs (camber etc.), or would more be needed?

BNaylor · 06-29-2007, 01:09 PM

Aftermarket upper strut mount/load bearings may cause noise but I don't believe the bouncy feeling is from the mounts. With your mileage more like strut springs. The rule of thumb is to stay with the OEM GM mounts. Too many problems with aftermarket brands that I know of. I took my own advice and went with KYB GR2 all around but with the stock mounts. The weight of the car may negate any play that you see.

As to the lowering kit from Eibach or other brands no major problems that I know of and many GP owners have them installed. If camber is off during the alignment check then you will need to adjust the camber via a camber kit. Checkout Eibach or you can use the low cost generic kits that are available which replaces one of the lower strut mounting bolts with an eccentric bolt. The strut holes have to be elongated for this type kit.

However, note that some GP owners with lowering kits complain about the pogo stick (bouncy) effect after installation.

a_alyte · 06-29-2007, 06:17 PM

Thanks for the input, I do appreciate it.

I'll contact the dealer to see how much they charge for mounts. As for the springs, is there any other brands that are popular with GT's, or would it be best to stay stock?

a_alyte · 07-17-2007, 12:38 PM

So now I have new KYB struts, KYB strut mounts, Gen 2 SSC lowering springs & anti pogo washers. I have no noise but the ride still feels too bouncy, mainly at highway speeds.

What's this all about?

Den69RS96 · 07-19-2007, 10:16 AM

I'm going to second the KYB strut mounts stink. I used them when I installed my gr2 struts. The bolts they supply for the rear are too short but work. The stock mounts had a long bolt which stuck out past the nuts. The kyb screws are too short and barely reach the end of the nut. They hold, but at least they could supply longer bolts. The fronts I removed and installed the old gm ones. After I installed the struts the dealership could not get my front end aligned. Removed the kyb front mount, put in the old gm ones and no problems.

a_alyte · 07-19-2007, 10:27 PM

My GT was extremely bouncy when I bought it at 133K miles. The first thing I did to the suspension was the KYB struts, I did notice a big difference. Now that I have the new springs & mounts, it feels like I'm just bouncing around. This is costing me too much money & it's driving me crazy.

I know what you mean about the rear KYB mounts, they seem universal and the bolts are too short. The KYB mounts are very expensive (they cost me more than the KYB struts) & the GM mounts are even more expensive.

I also had my car aligned after having the mounts & springs installed.

a_alyte · 01-12-2008, 01:29 PM

Update:

I removed my lowering springs & went factory, now my GT handles like a car rather than a ride at the amusement park

. My suspension now consist of KYB struts, KYB mounts, & OEM springs (Plus alignment).

I did like the look of my car with the lowering springs, but not enough to deal the shitty ride associated with it. If your upgrading your suspension & ride quality is important to you, I highly recommend sticking to the factory specs.

My

phaelax · 01-14-2008, 12:23 PM

I have the KYB struts and mounts (stock springs), but I haven't noticed any bouncing since I put them on 10k miles ago.

BNaylor · 01-14-2008, 01:20 PM

IMO the KYBs need some break in time. I noticed my GR2s were stiffer than stock and sort of bouncy but that disappeared. I use the stock GM upper strut mounts (front and rear) and load bearing (front). Stock strut coil springs.

a_alyte · 01-14-2008, 02:41 PM

I'm not sure if I made myself clear. The Gen 2 SSC lowering springs that I had paired with the kyb struts & mounts were the cause of my bouncy ride. Now that I replaced the Gen 2 SSC lowering springs with OEM springs, my ride is good. The KYB struts & mounts were not the cause of my bouncy ride.

BNaylor · 01-14-2008, 03:26 PM

Thats interesting. Many GP owners claim great success with the Superior Sport Chassis - Gen 2 SSC springs contrary to your experiences and definitely less problems than with Eibachs. Including using them with KYB brand struts. As a result ZZPerformance has been out of stock on these springs. Just my two cents worth but I think the real issue is pairing them with aftermarket KYB either the GR2 or AGX adjustable struts which are really generic in nature since the same by part number will fit and work in a Regal, Impala, Intrigue, etc. Less bounce with the AGX since they are adjustable. From what I understand they were designed and engineered to work properly with the stock GM struts which IMO are still the best overall if you can afford them. However, if you have the money and want to do it right probably best to go with GMPP/Koni products.

GMPP Package: 12498354

Assembled Strut/spring package, lowers car approx .9" in front, .7" in rear.

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