JohnR

iTrader: (1)

My '99 Firehawk has UMI Adjustable Trailing Arms. Currently, the arms are set to almost level, but slightly high in front. I'm getting a little wheel hop when I bang 2nd. I'm wondering if lowering the rear mounting position will improve traction. If so, how will it affect overall handling?
Thanks,
John

wannafbody

iTrader: (2)

I think the more you lower the rear position the harder it bites.

Scarebird

What does UMI say?

wlink14

I have never experienced wheel hop with my tubular low control arms and lower control arm relocation brackets. Perhaps your shocks are worn? Are all the bolts tight? What kind of traction device is in the rear? Spool, truetrac, eaton posi, etc?
When I lowered the rear arms more I gained a lot more traction.

lees02WS6

iTrader: (5)

Do you mostly street drive the car? The lower holes increase anti-squat. That may not rid wheel hop, but it may increase oversteer.

JohnR

iTrader: (1)

I sent them a note but haven't heard back.

I have a Strange 12 Bolt, friction plate posi, 4.10 gears, with KW double adjustable shocks. Tires are Michelin Pilot Sport 275/40-17.

The car is mostly a street car with some occasional spirited driving. I know that wheel hop can break things, but the unpredictable, sudden "Oversteer" is what I fear most. This is why I'm asking the question before I start making changes.

I appreciate all the great responses.
John

RPM WS6

iTrader: (3)

This.

Also, another side effect of too much anti-squat would be an increased risk of wheel hop under hard braking.

JohnR

iTrader: (1)

Here's what UMI said in response to my question about moving the rear trailing arm to a lower position:
"Yes, moving the lower trailing arm to the next lower position should help with your wheel hop issue and improve traction. The overall effect on handling will be very minimal on a street car and typically not noticeable. "

So now I'll try relocating the trailing arm and see what happens. On the other hand, I'll be out of town for a month. I'll continue this post in July.

Thanks to all for your help,
John

weedburner

Good chance clutch engagement is too aggressive.

Grant

JimMueller

iTrader: (9)

I installed UMI's weld-in lowering brackets in 2007. Snippets from the FRRAX autox/road racing forum are below.

"You'll want to start with them horizontal. Depending on car set up, you may want the axle mount to be a little lower than the body mount end. That will help plant the tires on acceleration. The LCAs on our 3rd Gen are about 1/2" lower on the axle mount end, and I like the way the car hooks on throttle application. With the axle end higher than the body mount end, you will reduce bite on acceleration, and can induce roll-understeer."

"As for hole patterns, use the closest ones that will get your LCAs level. The longer I play with geometry, I don't necessarily buy into roll oversteer being as big of a deal as it's made out to be. I really like the antisquat you pick up getting them closer to level."

"You should add the LCA brackets. The reason for this is that you want to keep the LCA's parallel to the ground for rear steer. The LCA brackets will allow you to lower the rear of the car and still maintain the LCA geometry. Without the LCA brackets you just can't lower the rear of the car as much as you'd like."