IronOutlaw

iTrader: (4)

Car is basically stock, it shouldnt have happend. It broke when I was pulling onto the highway into traffic and I almost got hit, I thought it was the rear end.

I need to prevent this from happening again and I think I may know the problem but would like other opinions.
Car is lowered with an eibach pro kit. I think my pinion angle is way off because of this. When I changed trannies I had to force the torque are onto the rearend to bolt it up. On my old firebird it just slipped on and off effortlessly.
Do yall think that LCA relocation brackets will get my pinion angle back normal? Car has really bad wheel hop so Im hoping to cure this to before my stall comes in the mail.
Thanks,

trent

kinglt-1

iTrader: (26)

Imo I would say you need adjustable lca's along with an adjustable tq arm.

SS RRR

iTrader: (2)

The lowering of your susp. has no influence on your pinion angle. Broken torque arms have been known to happen from stress fractures that finally give away from load transfer. The LCA relocation brackets are a good idea to aid in transferring load to the chassis so the torque arm doesn't have to do all the work.

camar0corey

iTrader: (22)

Just go with a adjustable, then you will know your pinion angle is at whatever you set it at, not some random condition.

Elliott's94Z

iTrader: (12)

Adjustable UMI torque Arm here...I would highly recommend looking into one. If not I have my stock one you can have.

NSTIGATR

iTrader: (4)

ive got a brand new UMI adjustable torque arm for you with new bushing. 250 shipped to your door...

sweetbmxrider

iTrader: (13)

chassis or tranny mounted?

ABA383

iTrader: (1)

My vote goes for getting the TA off of the trans tail shaft...I had a Spohn trans mounted TA and split the tailshaft...I have a Spohn cross brace mounted TA with 2 DS loops and I love it...UMI and BMR are also great choices too...

--Alan

ss.slp.ls1

iTrader: (36)

I broke my stock TA as well. It cracked where it bolts up to the diff. Snapped right as I downshifted to chase down an EVO.

I have a new stocker on there now, and a Spohn chromemoly adj tunnel mount TA waiting to go on.

NSTIGATR

iTrader: (4)

trans mounted....

IronOutlaw

iTrader: (4)

wow, I thought lowering the car moved the pinion angle some. Now I wonder why the TA didnt want to slide onto the rear.
This is from the Herron performance website under LCA relocation info...

"Product Information
Reposition your instant center by changing your lower control arm angle for improved traction. Brackets lower the rear of the control arm up to 3", a must for all lowered vehicles to correct lost suspension geometry. By lowering your vehicle, you are changing the lower control arm angle, allowing the rear mounting point to sit higher than the front. This will, in return, cause wheel hop and a great deal of traction loss.

Lowered Vehicles: We do not recommend lowering a 3rd or 4th generation F-Body without lower control arm relocation brackets due to the compromise in the geometry on the instant center. Brackets will significantly improve instant center position, eliminate wheel hop and increase traction. Brackets installed will also help 60-foot times of .10 or better, lower ETs and increase track consistency--a must for all lowered vehicles! "

So I must have gotten instant center and pinion angle mixed up, what is instant center?

SS RRR

iTrader: (2)

Because the diff wants to be at a different angle, but because you are forcing it into position there will be some resistance.
https://ls1tech.com/forums/ls1-domes.../t-396309.html

Z-RATED94

iTrader: (6)

I too have the Eibach Pros and it did change the pinion angle slightly. Relocation brackets, adj. panhard rod, lca's and a chassis mounted adj. Spohn TA straightened everything out.

ss.slp.ls1

iTrader: (36)

Was it a noticeable differences with those suspension parts? I will be doing the same very shortly?

Beaflag VonRathburg

iTrader: (176)

It's probably partially because it is either 15 or 12 years old depending on which vehicle it is in your sig.

SPDEMON

Actually lowering your car has all the influence in the world when it comes to changing the pinion angle.

Suspension geometry always has an effect on pinion angle.

In this case, you have a triangle. If you were to make a line straight off the tailshaft of your trans (as if the DS went straight back) that would be the top side of tha triangle. The driveshaft is the bottom side of the triangle, and the distance in between the two sides at the rear of the vehicle will be the third side.

When you change the dimensions of that third side, which will come from either lowering or lifting the suspension of the car, it will change the pinion angle unless you were to shim the rear axle housing (not usually done on a coil spring setup, mostly on leaf sprung set-ups, so not an option for us).

That is why it is mandatory (if you want max performance) to have an adjustable torque arm especially when you lower the car.

SO I am not sure why you would say that, when it is fairly common knowledge that the wheel hop associated with a lowered f-body is due to the change in pinion angle and the rear axle not biting into the pavement.

LCA relocation brackets will help correct the problem, but considering the TA is broke, get an Adj. TA and the LCA reloc. brkts and be done with it.

Z-RATED94

iTrader: (6)

I'm very happy with the way the car hooks, considering it's on lowering springs. A lot of that has to do with the adjustability I have now and the MT street radials. Their a great tire.
Don't forget when you lower the car, you throw the back end off side ways. You bring the back of the car back to center over the rearend with the adj. panhard bar.

SS RRR

iTrader: (2)

What you've stated is an interesting theory and all, however the pivot point between the drive shaft and yoke are not compromised no matter how into or out the chassis the differential sits. That is because the torque arm to differential is a fixed point. The only part of the differential, drive shaft and torque arm that changes angle is at the torque arm and tranny mount. Think about it. If what you said was correct the pinion angle would be changing constantly during normal suspension travel (ie over every bump/dip in the road).
The only time the pinion angle will change (and hopefully in a very minuscule fashion) is when there is extreme load (ie shock to the drive train) on the differential which forces the diff. in an upward fashion. This is where stress fractures can take place with the stock stamped steel torque arm which inevitably leads to breakage.
I blame wheel hop more on the angle of LCA's rather than pinion angle.

IronOutlaw

iTrader: (4)

Wow, this is gonna get more expensive than I thought. I cant find a stocker near me so I guess Im gonna bite the bullet and get an adjustable TA. Id like to keep it tranny mounted due to my car being lower on power, under 400 ponies, and to keep cost down. I just cant spend 400-600 bucks on a chassis mounted torque arm right now.

What would you guys use?

IronOutlaw

iTrader: (4)

Ok, I found these...
edelbrock
http://store.summitracing.com/partde...5&autoview=sku

UMI
http://store.summitracing.com/partde...5&autoview=sku