BlackScreaminMachine

iTrader: (17)

I have been researching this as best I can. So if anything sounds redundant or odd, pls don't mind.

I am well aware pinion angle has no tangible effect on traction, this is more for setting the right value to reduce some driveline vibration but when I start racing again the correct way to help with traction. There are 2 different methods but I am more interested in the ground method for this.

Specifications:

2002 T/A NON WS.6
- QA1 R Series front shocks, LT1 rated spring (I want to say 315# but I will recheck) Single Adj.
- Stock K members and A Arms
- TQ Arm Relocation Cross Member (UMI)
- BMR Adj. TQ arm
- UMI Drag Bar (no pre load right now, will be set when I race)
- QA1 Single Adj rear shocks
- Moser 12 Bolt
- Stock Spring, Isolator still in.
- 17" WS.6 Rim, i.e. Stock O/D tires

I do not have the ride weight measurements handy so I will get those if needed.

Basically With adding the TQ relocation kit the instant center is not based on stock but I do want a correct pinion angle so the drive line does not have too much bind as I am trying to track down a Vibration.

Also to mention the car has 45k Miles, Stock Motor mounts but a Poly trans mount with out preload plate. Since the TQ arm is off the trans this should not be a major factor but I will be swapping back the mount to see if there is a diff.

The virbation is bearly noticable until 70-80 mph so its very annoying and since I have a different TQ mount then stock, i need the instant center correct before worrying about the pinion angle.

The UMI TQ Arm cross member has many selections as a FYI.

Long story made short is that I am hearing about a method that you need to get the engine and rear end neutral balanced on the ground with preloaded rear and a arms. Then figure out if the rear needs to come up or down to get the correct instant center. Then from there I can play with the pinion angle.

** If I am off here, pls correct and no I am not interested in the BMR method for Pinion Angle

I have access to level ground as well as a drive on lift so everything will be loaded and I can sit in the driver seat so it will have a realistic representation of what the suspension will see when racing/driving.

So I am looking for more info and expert adv on achieving the correct setting.

If I am missing anything, pls tell me, questions, please ask me.

BlackScreaminMachine

iTrader: (17)

Bump. You would be surprised how little the info is out there for f body specific.

jimmyblue

iTrader: (11)

The right setting for torque arm angle, is what gets you
the bite you want (or best you can get). Moving the nose
down moves the instant center back (increased weight
transfer). This can be a long series of cut-and-try, your
technique is also in the picture and has to be eliminated
as a variable.

Pinion angle via the rear adjuster, is for killing the vibe
after the setting up for launch is done.

You want a slight negative bias in the driveline angle
because the suspension will wind up some under load.
I've seen guidance of -1 degree for a hard or poly
bushing setup and -2 for soft / stock.

wrencher

iTrader: (2)

The angle of the LCA's & the torque arm mounting point create the front to rear IC.
Move IC back/upward for traction, moving IC forward/lower improves heavy braking.( less prone to rear brake wheel hop)
The adjustments on your UMI dont change it a ton I'm betting.
The IC shouldn't create a vibration. Has to be a driveline imbalance or pinion adjustment. Once IC is in place the pinion should be set up.
I had these issues as well, it was 99% always pinion angle or driveshaft balances that cured them.

BlackScreaminMachine

iTrader: (17)

I appreciate all those that responded. I've heard this both ways but at this point I want to read some litature on this. Since there can be some variation on opinions it makes it hard to decide.

SS SLP2

iTrader: (8)

post # 3

"..... Moving the nose
down moves the instant center back (increased weight
transfer). ....."

POST # 4
"""....Move IC back/upward for traction, moving IC forward/lower improves heavy braking.( less prone to rear brake wheel hop)...""""

I would ask both of the above gentlemen to pardon, but I seem to read two different answers, I read one say move the front of the TA nose >>up to move the IC back and one answer say move the TA nose >>>down to move the IC back

I am sure I am missreading, some one PLEASE set me stright
Johnny

wrencher

iTrader: (2)

Also the length of the torque arm with have major influnence on the IC & anti squat under accel.
Remember the IC is caculated by the angle of the LCA's & the forward most mounting point of the TA.
So your kinda set in what you got with relocation brackets, ride height & your particular TA.
Major changes have to be done to make a big change.

The angle of the pinion is not a factor here.
This is liken to wheel alignment. It is chassis geometery
There are also IC's for the front & rear axles as viewed from the front & rear of the car.
Also refered to as roll center.
Same thing ride height & chassis configuration determine them.

It comes down to you need to chose the parts for your car with the intended use in mind.

Dave88LX

Does the information on this page help?
http://www.baselinesuspensions.com/

wrencher

iTrader: (2)

There's some good info there.
It's close but a torque arm suspension is kind of it's own entity.
Basically much more in common with a 3 link.
This has some decent info;
http://www.racetec.cc/shope/index.htm
TA IC calculator
http://www.racetec.cc/shope/tim.13.htm

But with F-cars you have to have a goal in mind for the use of the car.
The torque arm chosen will pre-determine a lot of these settings for you.