Lowering & pinion angles ?
06-12-2007, 11:19 PM
#1
2nd Gear Member
Thread Starter
Join Date: May 2007
Posts: 202
Lowering & pinion angles ?
If I install a eibach pro kit do I have to change my pinion angle and inwhat direction? I just put a DMJ lowering kit on my F150 and needed to change the angle. I would like to know before I get started thanks.
06-12-2007, 11:43 PM
#2
3rd Gear Member
Join Date: Oct 2006
Location: Sunshine State
Posts: 588
RE: Lowering & pinion angles ?
This may help you out...
The following was written by CrazyAl:
OK, here is the pinion angle setting procedure for an OEM 2-pc driveshaft. (This is NOT correct for a solid 1-pc aftermarket driveshaft)
First, lift up the car so that you can work under it. Be sure you use safe lifting procedures. Youmust have the rear suspension loaded--in other words, you need to have the tires on ramps or the rear axle tube on stands so the weight of the car is compressing the rear suspension.
It is best if the car is as level as you can get it, so if possible lift up the front to the same height as the rear. You're not going to be working on the front end, so it doesn't matter if the front suspension is loaded or not.
You are now ready to take measurements. I attached a rough sketch that shows where you are doing the measuring.
Now, use the angle gage to measure the angle of the driveshaft right next to the rear end. It doesn't really matter what this number is, just measure it and write it down. Take the measurement at the place labeled "1" on the sketch.
Move the angle gage over and measure the angle of the pinion itself. The actual pinion shaft isinside the rear end housing, so you have to take the measurement on the piniondrive flange. This isthe place makred "2" on the sketch. Make sure you are holding the gagefirmly on the wider part of the flange.Don't allow the gage to lean across the little step machined on it. (See the note on the sketch) Write this number down too.
You are interested in the difference between these two numbers. So, take the angle of the driveshaft and subtract the angle of the pinion from it.
The correct measurement will be about 3 to1.5 degrees difference, with the pinion being closer to horizontal than the driveshaft is. In other words, 0 degrees would have the measurements the same: The driveshaft and the pinion would be perfectly in line. You want the pinion to be angled down lower by about3 to 1.5 degrees. (Technically, this is called a negative angle, as in "-3 degree pinion angle", but wether or not the actual measurement is negative depends on how your angle gage is calibrated, so that is not always reliable)
If your measurement is not correct, then you need to adjust it. To do that, loosen the locknuts on your LCAs and then turn the center adjusters. Lengthening the LCAs will bring the nose of the pinion down, which will give you a larger angle difference. Be sure you have both LCAs set the same. You can either count turns and repeat the same change on both sides, or you can use a tape measure to measure the LCA lengths and keep them the same that way.
Once you've adjusted them a bit, check the angle again. Repeat adjusting and checking until the angle is where you want it. Once you've got it set, put a few drops of loctite on the adjusting nuts and tighten them down. Lower the car and go for a test drive.
How do you know what the proper angle is? Well, some of this is trial and error. You might have to reset it if things aren't to your liking. However, the general rule is that the more aftermarket parts you have in your rear suspension, the less the angle difference needs to be. 3.0-2.5 degrees is about right for a street car with relatively minor suspension mods. If you have a lot of aftermarket parts in the rear end (combo type UCA and LCAs+ more) then you could try 2.0 degrees instead. A full race setup might be 1.5 or even 1.0 degrees, though this would be an extreme situation: no rubber or polyanywhere in the rear suspension, reenforced frame, etc.
What is the theory behind this? Well, when you accelerate hard the whole axle assembly rotates a bit. Newton said every action has an equal and opposite reaction. Well, when the engine turns the wheels, a reaction torque is applied to the axle. On a race car with a SOLID suspension nothing much happens, but on a street car the rubber/poly bushings flex a bit and the axle housingrotates a little. You are setting it up so that when you get on the gas hard, and the axle twists a bit, THEN the driveshaft and the pinion are in perfect alignment. [end of article]
The following was written by CrazyAl:
OK, here is the pinion angle setting procedure for an OEM 2-pc driveshaft. (This is NOT correct for a solid 1-pc aftermarket driveshaft)
First, lift up the car so that you can work under it. Be sure you use safe lifting procedures. Youmust have the rear suspension loaded--in other words, you need to have the tires on ramps or the rear axle tube on stands so the weight of the car is compressing the rear suspension.
It is best if the car is as level as you can get it, so if possible lift up the front to the same height as the rear. You're not going to be working on the front end, so it doesn't matter if the front suspension is loaded or not.
You are now ready to take measurements. I attached a rough sketch that shows where you are doing the measuring.
Now, use the angle gage to measure the angle of the driveshaft right next to the rear end. It doesn't really matter what this number is, just measure it and write it down. Take the measurement at the place labeled "1" on the sketch.
Move the angle gage over and measure the angle of the pinion itself. The actual pinion shaft isinside the rear end housing, so you have to take the measurement on the piniondrive flange. This isthe place makred "2" on the sketch. Make sure you are holding the gagefirmly on the wider part of the flange.Don't allow the gage to lean across the little step machined on it. (See the note on the sketch) Write this number down too.
You are interested in the difference between these two numbers. So, take the angle of the driveshaft and subtract the angle of the pinion from it.
The correct measurement will be about 3 to1.5 degrees difference, with the pinion being closer to horizontal than the driveshaft is. In other words, 0 degrees would have the measurements the same: The driveshaft and the pinion would be perfectly in line. You want the pinion to be angled down lower by about3 to 1.5 degrees. (Technically, this is called a negative angle, as in "-3 degree pinion angle", but wether or not the actual measurement is negative depends on how your angle gage is calibrated, so that is not always reliable)
If your measurement is not correct, then you need to adjust it. To do that, loosen the locknuts on your LCAs and then turn the center adjusters. Lengthening the LCAs will bring the nose of the pinion down, which will give you a larger angle difference. Be sure you have both LCAs set the same. You can either count turns and repeat the same change on both sides, or you can use a tape measure to measure the LCA lengths and keep them the same that way.
Once you've adjusted them a bit, check the angle again. Repeat adjusting and checking until the angle is where you want it. Once you've got it set, put a few drops of loctite on the adjusting nuts and tighten them down. Lower the car and go for a test drive.
How do you know what the proper angle is? Well, some of this is trial and error. You might have to reset it if things aren't to your liking. However, the general rule is that the more aftermarket parts you have in your rear suspension, the less the angle difference needs to be. 3.0-2.5 degrees is about right for a street car with relatively minor suspension mods. If you have a lot of aftermarket parts in the rear end (combo type UCA and LCAs+ more) then you could try 2.0 degrees instead. A full race setup might be 1.5 or even 1.0 degrees, though this would be an extreme situation: no rubber or polyanywhere in the rear suspension, reenforced frame, etc.
What is the theory behind this? Well, when you accelerate hard the whole axle assembly rotates a bit. Newton said every action has an equal and opposite reaction. Well, when the engine turns the wheels, a reaction torque is applied to the axle. On a race car with a SOLID suspension nothing much happens, but on a street car the rubber/poly bushings flex a bit and the axle housingrotates a little. You are setting it up so that when you get on the gas hard, and the axle twists a bit, THEN the driveshaft and the pinion are in perfect alignment. [end of article]
06-12-2007, 11:49 PM
#3
5th Gear Member
Join Date: Mar 2006
Location: Nor Cal
Posts: 2,179
RE: Lowering & pinion angles ?
Simple answer yes. However there are also several other mods that should also be done. You will also need a adj. panhard bar to center the axle. You will need camber bolts up front for the proper alignment. To adjust the pinion you can go two ways Adj. UCA or Adj. LCA. My method of choice is Adj. UCA.
Here is a great reference thread that is almost a must read.
https://mustangforums.com/m_2727670/tm.htm
https://mustangforums.com/m_1624504/tm.htm
Here is a great reference thread that is almost a must read.
https://mustangforums.com/m_2727670/tm.htm
https://mustangforums.com/m_1624504/tm.htm
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