[nazz07]

Im having trouble with my rear end and new 1 pc drivshaft,car is lowered in rear 1.5 inches and i cant seem to get the pinion angle correct in there a specific tool for the rear end that i can get this angle correct Insructions with driveshaft says 2.7 degees up can anyone shed some light on the subject please????

[sqidd]

Originally Posted by nazz07

Im having trouble with my rear end and new 1 pc drivshaft,car is lowered in rear 1.5 inches and i cant seem to get the pinion angle correct in there a specific tool for the rear end that i can get this angle correct Insructions with driveshaft says 2.7 degees up can anyone shed some light on the subject please????

How to set your pinion angle correctly.

You can use jackstands to support the axle, ramps or a drive on lift which is best. The first thing you need to do is measure your rear ride height though. Measure the distance from the tire to the fender lift (vertically). This is your ride height. You HAVE TO check/set pinion angle at this ride height or you are wasting your time. You will find it is very hard to replicate the cars ride height if you are not using a drive on lift. I ended up using ramps with 48-lb of sandbags in the trunk to replicate mine. So there is your first challenge. You don’t do it right you are wasting the rest of your time.

The biggest misconception is what “negative” pinion angle is. Negative minion angle is an angle less than where you would set the driveline angles at in an ideal world where the axle doesn’t “wind up” under launch. If you are going for a -2* angle it needs to be X-2*, X being what the perfect driveline angle is. The perfect driveline angle is when the pinion angle and the transmission tailshaft angle are in “phase”. You need to set, or at least figure out then do the math based on the driveshaft being in “phase”. Here is a link that explains it in detail. Like ride height if you do not figure out what your driveline angles need to be set at to be in phase before you go adjusting for a negative pinion angle you are wasting your time. The angle of your driveline while in “phase” should be considers “zero”. If you do not find that zero you have on basis for any math from that point on.

The Rodding Roundtable - Driveline Angles Explained

Now that you have your driveline running in “phase” its time to set your driveline angle for dragstrip launches. If you are not doing drag launches you don’t need or want any negative pinion angle as long as you have quality control arms. The pinion changes angle very, very little if you have quality control arms. I have tested this with my data acquisition system and potentiometer hooked up to the pinion. Unless you are running drag radials and have at least 350hp leave your driveline set in “phase” or zero. Your pinion barely deflects when you drop the clutch with under 350hp or you are running real drag radials.

If you are putting down some pony’s and running sticky rubber the pinion will deflect when the clutch is dropped, but not much and not for long. -2* is pretty extreme and I would only run it for a car that was at the track a lot and getting 60ft times under 1.8sec. The reason being that if you are just driving down the road at -2* you are putting a lot of strain on your U-joints (they are out of phase) and the car will have less rear wheel horsepower. And lastly you will get a high speed vibration. For a car that has good control arms, goes to the track but also drives around on the street I would set it up at -1*.

Ok, back on point. So you are under your car and you have already set the driveshaft up “in phase”. If you want to set the pinion at -1* all you need to do is take the current pinion angle that you just set, which could be just about anything depending on if the car is level, etc. and adjust the pinion 1* down from there. A -1* pinion angle is simply your in “phase” pinion angle minus one. It is irrelevant what the in phase number is.

• Get a good digital angle finder.
• Have a few pieces of angle aluminum (the kind you can get at Home Depot) to use as a “base” for the gauge.
• Get the car in the air.
• Exactly replicate the rear ride height
• Put jack stands under where the K-member meets the floorpan then put your jack under the K-member right under the motor. Jack the jack up until the weight of the car is just coming off of the front jackstands. This is to remove the droop that the front end of the car has when supported by the “tub” and the wheels are not loaded. It’s a lot more than you would imagine and it changes the transmissions output shaft angle considerably. And unless your Trans output shaft is at the angle that it is while the car is on the ground you will not calculate your “in phase” angles correctly and everything after that will be wrong.
• Take your time
• Measure everything a BILLION times. There are a ton of variables. You will find that you will not get repeatable measurements unless you start to eliminate them. Only after you can take all of the measurements 3-4 times in a row with no changes have you eliminated all the variables.
• Keep in mind, 1* is very, very small. This is not a rough adjustment. It is therefore very easy to be 3* off just because of how you are placing the angle finder. This is where repeatability comes into play. If it does not repeat, you don’t know what you have.

[Itchy]

Sqidd,

slightly off topic, but did you go back to the factory 2 piece drive-shaft? I know from your previous post that you have a lot of experience battling drive-shaft vibration.

[nazz07]

I tried old shaft with no difference in sound or vibration.I guess this is something that a pro should be doing.Im relly feeling beaten down from this.I changed gears to 373s and the car hasnt been the same since.Even had the old gears put back in and im still having similiar issuies.

[Mr. Ugly]

Dang...

Sqidd is the man!

[sqidd]

Originally Posted by Itchy

Sqidd,

slightly off topic, but did you go back to the factory 2 piece drive-shaft? I know from your previous post that you have a lot of experience battling drive-shaft vibration.

Yeah, I'm back with the stock shaft. With the angles set up perfect it has been real nice. When I had my new wheels widened they trued them up PERFECT too. That helped out. The welder told me he has never seen a wheel, even new that was perfectly true out of the box unless you are talking about the ones that are $1000/wheel+. I had the car up to 184 a few weeks back while CRUSHING a turbo 350Z. It was smooth as glass.

I need to find a better solution though. I am always thinking about the shaft when the speeds are high. I've had a shaft drop out of a car doing 130+ and it tore the back half of the trans, 2 NHRA safty loops and a lot of the trans tunel right out of the car. I have no idea how high we got off of the ground but I was certain we were going to be using the roll cage. We lucked out and the car landed on its wheels and I managed to keep it mostly on the road though. I'm not exactly excited about doing that again.

Come spring I will be twisting 650rwhp on pump and 750rwhp on race fuel. I plan on doing the Maxton Mile and getting my 200mph certificate (unfortunately they don't give those out on the interstate) and then I am thinking of doing the Silver State Classic. I don't think the stock shaft is the way to go. I have been talking with a custom shaft maker that does a lot of 4x4 stuff and we are looking at doing a 2pc with all CV joints. I'm not looking for light as the most important thing. I need it to be harmonics free and strong. I have all winter to deal with it and its not like anything else on the car has to wait on the shaft though.


Maybe I will just get a bunch of slightly used take offs and change them out every couple of runs.

[Scrochy]

Originally Posted by sqidd

How to set your pinion angle correctly.

You can use jackstands to support the axle, ramps or a drive on lift which is best. The first thing you need to do is measure your rear ride height though. Measure the distance from the tire to the fender lift (vertically). This is your ride height. You HAVE TO check/set pinion angle at this ride height or you are wasting your time. You will find it is very hard to replicate the cars ride height if you are not using a drive on lift. I ended up using ramps with 48-lb of sandbags in the trunk to replicate mine. So there is your first challenge. You don’t do it right you are wasting the rest of your time.

The biggest misconception is what “negative” pinion angle is. Negative minion angle is an angle less than where you would set the driveline angles at in an ideal world where the axle doesn’t “wind up” under launch. If you are going for a -2* angle it needs to be X-2*, X being what the perfect driveline angle is. The perfect driveline angle is when the pinion angle and the transmission tailshaft angle are in “phase”. You need to set, or at least figure out then do the math based on the driveshaft being in “phase”. Here is a link that explains it in detail. Like ride height if you do not figure out what your driveline angles need to be set at to be in phase before you go adjusting for a negative pinion angle you are wasting your time. The angle of your driveline while in “phase” should be considers “zero”. If you do not find that zero you have on basis for any math from that point on.

The Rodding Roundtable - Driveline Angles Explained

Now that you have your driveline running in “phase” its time to set your driveline angle for dragstrip launches. If you are not doing drag launches you don’t need or want any negative pinion angle as long as you have quality control arms. The pinion changes angle very, very little if you have quality control arms. I have tested this with my data acquisition system and potentiometer hooked up to the pinion. Unless you are running drag radials and have at least 350hp leave your driveline set in “phase” or zero. Your pinion barely deflects when you drop the clutch with under 350hp or you are running real drag radials.

If you are putting down some pony’s and running sticky rubber the pinion will deflect when the clutch is dropped, but not much and not for long. -2* is pretty extreme and I would only run it for a car that was at the track a lot and getting 60ft times under 1.8sec. The reason being that if you are just driving down the road at -2* you are putting a lot of strain on your U-joints (they are out of phase) and the car will have less rear wheel horsepower. And lastly you will get a high speed vibration. For a car that has good control arms, goes to the track but also drives around on the street I would set it up at -1*.

Ok, back on point. So you are under your car and you have already set the driveshaft up “in phase”. If you want to set the pinion at -1* all you need to do is take the current pinion angle that you just set, which could be just about anything depending on if the car is level, etc. and adjust the pinion 1* down from there. A -1* pinion angle is simply your in “phase” pinion angle minus one. It is irrelevant what the in phase number is.

• Get a good digital angle finder.
• Have a few pieces of angle aluminum (the kind you can get at Home Depot) to use as a “base” for the gauge.
• Get the car in the air.
• Exactly replicate the rear ride height
• Put jack stands under where the K-member meets the floorpan then put your jack under the K-member right under the motor. Jack the jack up until the weight of the car is just coming off of the front jackstands. This is to remove the droop that the front end of the car has when supported by the “tub” and the wheels are not loaded. It’s a lot more than you would imagine and it changes the transmissions output shaft angle considerably. And unless your Trans output shaft is at the angle that it is while the car is on the ground you will not calculate your “in phase” angles correctly and everything after that will be wrong.
• Take your time
• Measure everything a BILLION times. There are a ton of variables. You will find that you will not get repeatable measurements unless you start to eliminate them. Only after you can take all of the measurements 3-4 times in a row with no changes have you eliminated all the variables.
• Keep in mind, 1* is very, very small. This is not a rough adjustment. It is therefore very easy to be 3* off just because of how you are placing the angle finder. This is where repeatability comes into play. If it does not repeat, you don’t know what you have.

this looks familar...............

[sqidd]

Originally Posted by Scrochy

this looks familar...............

The search function must be broken again

[nazz07]

do you think that the dealer would be able to do this correctly??

[Back@itagain]

Originally Posted by nazz07

I tried old shaft with no difference in sound or vibration.I guess this is something that a pro should be doing.Im relly feeling beaten down from this.I changed gears to 373s and the car hasnt been the same since.Even had the old gears put back in and im still having similiar issuies.

Ford balances the rear diff. assembly to help fight harmonics issues. Thats part of the reason why so many people have problems with gear changes. Another reason why it is not recommended to remove the pinion flange adapter when going to a 1-pc D/S since doing so can cause even the slightest change and throw off the balance.