Rearend Angle
03-21-2006, 11:43 AM
#1
Rearend Angle Does lowering the car, Eibach Prokit, affect the angle of the drive shaft to rear end? I am installing an adjustable pan hard bar and LCA's but I read on here that pinion angle was affected when I lowered it. Should I consider something more to realign this or not worry about it? Check the sig to see what I have doe to the car. I will also be putting 3:73 gears in the car and a 3400 stall all before Christmas as well as the girdle stud kit when I do the gear change. Your thoughts?
03-22-2006, 11:32 PM
#4
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Agree if you lower you'll want the LCA brackets. Also recommend and adjustable torque arm to adjust your pinion angle. You can always lower it and see how it works but my experience was that it required adjusting.
03-23-2006, 02:15 PM
#5
Confusion has set in!! What diference does it make to move the position of the LCA's? I can see buying the Torque arm but I cant see the justification of relocating the LCA's, maybe I am not seeing the whole picture, could you explain it please? Thanks
03-23-2006, 02:28 PM
#6
It moves...
Originally Posted by ss4chad
Confusion has set in!! What diference does it make to move the position of the LCA's? I can see buying the Torque arm but I cant see the justification of relocating the LCA's, maybe I am not seeing the whole picture, could you explain it please? Thanks
I'd use the RANDOM kit, and set the pinion at 3* down, to start with. [Selfish motive: I helped design and build the first Random pieces..
]The wheel hop can be traced to worn shocks, tire psi too low, bad suspension bushings, etc.
To make the car hook, you may want to remove the ft swaybar, and install adj shocks on all 4 corners. These mods will increase the pitch rotation of the chassis, planting the tires, and keeping them there. The shocks, t. arm, lowers, drops, will make the chassis more tuneable.
03-24-2006, 06:55 AM
#7
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Stating to set the pinion at 3 degrees down without further elaboration is sensless - PA is the relationship between an imaginary centerline drawn thru your crankshaft/tranny output shaft and an imaginary centerline drawn thru your pinion shaft. these (2) imaginary centerlines should be adjusted to be PARRALLEL (not in-line) by properly setting your PA with adj. T/A for the least amount of vibration (this is how car is set up from factory).
For example: if when you measure the engine/tranny angle it is 2 degrees pointing DOWN to the ground - the rear angle should be adjusted to be 2 degees pointing UP for a zero degree PA.
If you use the car on strip frequently and have considerable HP/TQ you can set your PA to -1 or -2 degrees...
So again if the engine/tranny angle is 2 degrees DOWN - the rear angle would be 1 degree UP for a -1 degree PA, and zero degrees for a -2 degree PA
For example: if when you measure the engine/tranny angle it is 2 degrees pointing DOWN to the ground - the rear angle should be adjusted to be 2 degees pointing UP for a zero degree PA.
If you use the car on strip frequently and have considerable HP/TQ you can set your PA to -1 or -2 degrees...
So again if the engine/tranny angle is 2 degrees DOWN - the rear angle would be 1 degree UP for a -1 degree PA, and zero degrees for a -2 degree PA
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03-24-2006, 08:40 AM
#8
??????????
Originally Posted by 1QUIKWS6
Stating to set the pinion at 3 degrees down without further elaboration is sensless - PA is the relationship between an imaginary centerline drawn thru your crankshaft/tranny output shaft and an imaginary centerline drawn thru your pinion shaft. these (2) imaginary centerlines should be adjusted to be PARRALLEL (not in-line) by properly setting your PA with adj. T/A for the least amount of vibration (this is how car is set up from factory).
For example: if when you measure the engine/tranny angle it is 2 degrees pointing DOWN to the ground - the rear angle should be adjusted to be 2 degees pointing UP for a zero degree PA.
If you use the car on strip frequently and have considerable HP/TQ you can set your PA to -1 or -2 degrees...
So again if the engine/tranny angle is 2 degrees DOWN - the rear angle would be 1 degree UP for a -1 degree PA, and zero degrees for a -2 degree PA
For example: if when you measure the engine/tranny angle it is 2 degrees pointing DOWN to the ground - the rear angle should be adjusted to be 2 degees pointing UP for a zero degree PA.
If you use the car on strip frequently and have considerable HP/TQ you can set your PA to -1 or -2 degrees...
So again if the engine/tranny angle is 2 degrees DOWN - the rear angle would be 1 degree UP for a -1 degree PA, and zero degrees for a -2 degree PA
03-24-2006, 09:00 AM
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A little touchy today eh? You must agree that just stating to set the pinion at 3 degrees down is pretty vague.
And in this case I do have it covered as quite a few of us have vibration problems and are trying to find the solution. PA is one of the suspect variables. There are about as many suggestions/instructions out there as to how to correctly set the pinion angle as there are members with the vibration problem
I finally went to the trouble to contact a GM Engineer that designs the cars to get the process staright from the source. So it just irks me a bit when people just throw out statements as how they think PA should be set and at what value.
Thanx for the sarcastic praise
And in this case I do have it covered as quite a few of us have vibration problems and are trying to find the solution. PA is one of the suspect variables. There are about as many suggestions/instructions out there as to how to correctly set the pinion angle as there are members with the vibration problem
I finally went to the trouble to contact a GM Engineer that designs the cars to get the process staright from the source. So it just irks me a bit when people just throw out statements as how they think PA should be set and at what value.
Thanx for the sarcastic praise
03-24-2006, 09:19 AM
#10
Good for you...
Originally Posted by 1QUIKWS6
A little touchy today eh? You must agree that just stating to set the pinion at 3 degrees down is pretty vague.
And in this case I do have it covered as quite a few of us have vibration problems and are trying to find the solution. PA is one of the suspect variables. There are about as many suggestions/instructions out there as to how to correctly set the pinion angle as there are members with the vibration problem
I finally went to the trouble to contact a GM Engineer that designs the cars to get the process staright from the source. So it just irks me a bit when people just throw out statements as how they think PA should be set and at what value.
Thanx for the sarcastic praise
And in this case I do have it covered as quite a few of us have vibration problems and are trying to find the solution. PA is one of the suspect variables. There are about as many suggestions/instructions out there as to how to correctly set the pinion angle as there are members with the vibration problem
I finally went to the trouble to contact a GM Engineer that designs the cars to get the process staright from the source. So it just irks me a bit when people just throw out statements as how they think PA should be set and at what value.
Thanx for the sarcastic praise
My "thinking" is the result of many tests, and alot of yrs of experience.
As for the vibration, I've discussed this with our driveshaft mfgr. His findings were that approximately 90% of the vibration problems he's investigated, with the F-body cars, was due to OEM driveshafts being bent. He sees this, when shafts are brought in for a "rebalance", when the owners are looking for the vibration.
His comment was" beat on them, and they will bend".
03-24-2006, 10:54 AM
#11
Ok, you two fight on another thread, can we get back to my question? Should I buy an adjustable torque arm to remedy this PA thing? How do I set it to 2 or 3 degrees? I dont have a big cam and I am not spraying and even if I did it would be a small shot, 50-100, I will be getting 3:73 gears and a 3000 to a 3400 stall. Now back to my question!! Should I adjust this PA or is it ok like it is? Would a UMI adjustable torque arm fix this? Do I still need to buy LCA relocation brackets?
1QUIKWS6, OLD Geezer? If I have to come over there I'm gonna whoop both of ya!! Now stop arguing!! Damm Kids!!
1QUIKWS6, OLD Geezer? If I have to come over there I'm gonna whoop both of ya!! Now stop arguing!! Damm Kids!!
03-24-2006, 12:10 PM
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I thought that my first reply did touch on how to set your PA as far as the concept goes? How you actually physically adjust the T/A that you choose would be in the mfg. instructions.
Personally, If I was lowering my car I would go with an adj. T/A. But that is your choice. I went with the Spohn T/A for LT's with the double DS safety loops due to the numbers I was already putting down at the wheels and the fact that I knew I was going to be adding more. One thing you could do is check your PA with the factory T/A after all the other components are installed - then if the angle is off - you know for sure you need one. This will cost you some time - but could save you a lot of $$.
You can't go wrong with a UMI product - high quality and good pricing. You then have a choice as to either go with a T/A that mounts to the tranny tailshaft as stock - or go with a version that uses a crossmember that bolts in place of your tunnel brace.
There are upsdides and down sides to each:
The tailshaft mounted version will usually be quieter due to the stock style of mount - but under higher HP/TQ from stock you risk breaking the tranny tailshaft housing (especially if you want to lock your verter @ WOT while on the dyno).
The body mounted front mount such as on the Spohn will relieve any stress from your tranny tailshaft - but due to the pivoting style mount you will hear a clunk when the car shifts and there will be more noise/vibration imparted from the T/A thru the floor of the car.
OK, dad - now you can come over and 'try' to whoop me
Hope I helped you out at least a little...
-Jay-
Personally, If I was lowering my car I would go with an adj. T/A. But that is your choice. I went with the Spohn T/A for LT's with the double DS safety loops due to the numbers I was already putting down at the wheels and the fact that I knew I was going to be adding more. One thing you could do is check your PA with the factory T/A after all the other components are installed - then if the angle is off - you know for sure you need one. This will cost you some time - but could save you a lot of $$.
You can't go wrong with a UMI product - high quality and good pricing. You then have a choice as to either go with a T/A that mounts to the tranny tailshaft as stock - or go with a version that uses a crossmember that bolts in place of your tunnel brace.
There are upsdides and down sides to each:
The tailshaft mounted version will usually be quieter due to the stock style of mount - but under higher HP/TQ from stock you risk breaking the tranny tailshaft housing (especially if you want to lock your verter @ WOT while on the dyno).
The body mounted front mount such as on the Spohn will relieve any stress from your tranny tailshaft - but due to the pivoting style mount you will hear a clunk when the car shifts and there will be more noise/vibration imparted from the T/A thru the floor of the car.
OK, dad - now you can come over and 'try' to whoop me
Hope I helped you out at least a little...
-Jay-
