Wobble in the Rear

[LEETHL]

Hello Everyone,
I'm new here, but not new to cars or modifications. I've got a problem however that's got me (and friends) absolutely stumped. We had taken a day to install all of the modifications below, I knew after the lowering springs that I would need an alignment, and rightfully so the toe was pretty far off (it could be felt while taking it to the alignment shop). After the alignment things were much better, however now when cruising at highway speeds and taking a "curve" to the right or hitting a "bump" such as the transition to/from an overpass the rear end gets very "squirrely" and it is/was very panic inducing (note that it does not doing this if taking a curve to the left).

• AFE MOMENTUM GT COLD AIR INTAKE SYSTEM W/ PRO 5R MEDIA
• THERMAL R&D 3" CAT-BACK EXHAUST SYSTEM WITH MID PIPES
• LETHAL PERFORMANCE LOWERING SPRINGS
• FENFABRICATION "DIFFY STIFFY" BRACE
• Tune from Unleashed Tuning

I've since had it aligned again, to no change. The sway bar set just showed up Thursday and we installed it last night, upon taking the vehicle for a test drive, the issue seems to persist. I'm going to take it for another alignment since we had part of the suspension apart for the Sway Bar install, but I don't think that'll help.

• AFE CONTROL SWAY BAR SET

We've double checked all suspension related nuts/bolts and everything is tight. We've got 2 hypothesis's (the shocks are oversprung from the lowering springs, or it's bumpsteering), but unsure how likely either are, I've been unable to find any threads on here for people with similar mods having a similar issue.

If anyone has any ideas or have experienced something similar and have been able to resolve that information would be extremely helpful.

Thank You!
-Austin

 

[Cdubya]

Not sure if you've read, but the lethal rear springs are FLAWED. I would not have even put those on if I were you and waited until they corrected things.

 

[LEETHL]

Not sure if you've read, but the lethal rear springs are FLAWED. I would not have even put those on if I were you and waited until they corrected things.

I have not seen that. I don’t know how I missed it. I’ll see about ordering a different brand and returning the Lethal Performance springs then.

Thank you,
-Austin

 

[Cdubya]

Lethal spring thread

 

[jrgoffin]

Whenever guys slam their cars - most just because they think it looks ‘cool’ - you are throwing the alignment out of whack and potentially adding bump steer issues. Fortunately with plenty of other vehicles out there, parts are available to correct and remedy the situation. Not so here. Now with every bit of jounce and rebound (especially when lowered a lot), you are going to find out it tracks weird.

Here’s some good reading on the subject (albeit for an ‘03 Cobra):
http://terminator-cobra.com/chassis & steering.htm#Alignment_&_bump-steer

 

[blackdog]

Go back to the stock springs and see if that changes or resolves the issue.

 

[LEETHL]

Whenever guys slam their cars - most just because they think it looks ‘cool’ - you are throwing the alignment out of whack and potentially adding bump steer issues. Fortunately with plenty of other vehicles out there, parts are available to correct and remedy the situation. Not so here. Now with every bit of jounce and rebound (especially when lowered a lot), you are going to find out it tracks weird.

Here’s some good reading on the subject (albeit for an ‘03 Cobra):
http://terminator-cobra.com/chassis & steering.htm#Alignment_&_bump-steer

Thanks' for this link, it was a good read. I'm just baffled as this is my 4th vehicle I've lowered, I've gotten alignments done on all immediately after dropping them. But I haven't encountered this issue before. That's partially why I was so baffled at the result in this particular application.

Go back to the stock springs and see if that changes or resolves the issue.

I've just read up on the thread Cdubya provided about Lethals spring issues, it seems most of them are noise issues, but erring on the side of caution I'll be replacing these with the H&R's which it seems is the choice for most and haven't seen issues with (they do sit about 1/2" higher than the Lethals, so I'll give them a try with a fresh alignment to see if those help. If not, going back to stock will be my next option. If it's still an issue, I guess I'll have to reluctantly take it to the dealership to see what's up.

Think's all for your suggestions. I'll update here after the changes.

Cheers,
-Austin

 

[LEETHL]

Update: Replacing the Lethal performance springs with H&R springs has fixed the issue. Surprised no one else with the Lethals had this particular issue. Live and learn, wish I had done a bit more research before buying the Lethals. Would have saved me some time.

Thanks everyone for your input!


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