Pinion angle help.

[Treblig]

update.. I put rear in car front wheels sitting on ramps and rear sitting on spring perches U bolted (tight but enough to move) with tires on and sitting on blocks. Car level and all weight on wheels , and set pinion angle at 3 *. And I put a 2x4 between the tire and leaf spring on both sides (thinking that would square up the rear). Unfortunately, after finishing up everything I test drove car and There is a noise on exceleration at any speed. I pulled third member took it and had it re-setup, put it back in and test drove again and noise on exceleration. Totally frustrated, I put car on lift and measured left to right between leaf spring and backing plate and found that the driver side and passenger side are not even. Would this cause the Noise ? Or is the pinion angle still off or both? The third member has all new parts and only aprox. less than 20 miles on everything. all thoughts and comments on this welcome.

side to side not being centered shouldn't make any difference. u said 3 degrees. the pinion should b 3 degrees down from the trans/eng angle. if ur engine driveline in 3 degrees down the the pinion should b 6 degrees down.

treblig

 

[67Dart273]

If your transmission shaft centerline is 1 degree down from level and you set the pinion at 3 down from level that is FOUR DEGREES. Seems to me that's getting a little much. All this has to be measured with loaded weight on suspension, with suspension ride height at normal driving height. This is ALSO somewhat of an estimate depending on your rear springs........factory stockers, cheesy 6 banger, or really beefed. They will twist "more or less."

The two shafts........the transmission shaft centerline........and the pinion shaft are to be PARALLEL under full house power.

 

[67Dart273]

side to side not being centered shouldn't make any difference. u said 3 degrees. the pinion should b 3 degrees down from the trans/eng angle. if ur engine driveline in 3 degrees down the the pinion should b 6 degrees down.

treblig

I thought he said the trans is 1 down, but your reasoning is certainly.............WAIT A MINUTE, no if trans is pointing down, you want the pinion UP..... "We were both typing" LOL

If the trans is 3 down, and you put the pinion 6 down, then if the pinion torques up 3, that will put both angles down, not parallel

 

[Treblig]

I thought he said the trans is 1 down, but your reasoning is certainly.............WAIT A MINUTE, no if trans is pointing down, you want the pinion UP..... "We were both typing" LOL

If the trans is 3 down, and you put the pinion 6 down, then if the pinion torques up 3, that will put both angles down, not parallel

if the trans is down 3 degree (example) the pinion should b down 6 degrees so that when u accelerate the pinion "will rise up" about 3 degrees which will then b parallel to the engine/trans driveline. The thing that ur trying to accomplish is to get the eng/trans angle parallel to the pinion angle during acceleration. the pinion always risesup when u hit the gas.
treblig

 

[67Dart273]

Yeh, but he said the trans shaft is DOWN, this means the pinion must actually be UP above level to be parallel. You were useing? example? of trans shaft down 3 which would be a lot. The pinion would have to be UP 3 to be parallel, and so if you allow 2-3 degrees in that case for "wrap" you would start out with the pinion level or up a degree

 

[Treblig]

Yeh, but he said the trans shaft is DOWN, this means the pinion must actually be UP above level to be parallel. You were useing? example? of trans shaft down 3 which would be a lot. The pinion would have to be UP 3 to be parallel, and so if you allow 2-3 degrees in that case for "wrap" you would start out with the pinion level or up a degree

s
so if the trans is down 3 the pinion should b set at 0 so that when it comes up 3 ( acceleration ) it will b up 3 making it parallel??
so if his trans is down 1 then he should set the pinion 2 down so that it will rise 3 putting it 1 up during acceleration???

treblig

 

[va-mopar]

It's a 70 Duster that had a 318 with 904 trans and 7 1/4 rear. I dropped in a Blt. 360 and a 8 3/4 rear. It still has 904 tranny. Just stock leaf spring car. no traction bars ,yet. When I just took angle off tailshaft it was 1 degree down. and I set the rear end at 3 down.

 

[va-mopar]

So, if the rear is sitting off to the passenger side 1 to 1 1/4 inch more than the driver side, that's not a Problem? As soon as I can get it back in shop, I will recheck everything starting with angle at trans and at pinion. With drive shaft in. And side to side measurements and post my findings. Thanks' guys.

 

[67Dart273]

When you say "off" you mean the pinion left/ right centerline? That is likely normal as long as the shaft has room in the tunnel

I think 3 down is too much with the trans down. Look at it this way. If the trans was leveled (0 degrees) you would have to jack up the rear of the car. This would put the pinion FOUR down. Do you think it will "wrap" enough to get from 4 to zero? Doubt it. I hear "talk" on here about the pinion 2 or so down. Wish I had an unmolested car to check it LOL

 

[va-mopar]

When you say "off" you mean the pinion left/ right centerline? That is likely normal as long as the shaft has room in the tunnel

I think 3 down is too much with the trans down. Look at it this way. If the trans was leveled (0 degrees) you would have to jack up the rear of the car. This would put the pinion FOUR down. Do you think it will "wrap" enough to get from 4 to zero? Doubt it. I hear "talk" on here about the pinion 2 or so down. Wish I had an unmolested car to check it LOL

I meen, the whole rear end is sitting off center 1 to 1/2 inches toward the passenger side.

 

[va-mopar]

Ok, I finally got a chance to re check here is what I found out.............. The Transmission output is 1 Degree down. rear Pinion is 3 1/2 Degrees Down. And , Rear end is off center 1/2 to 3/4 of a inch towards passenger side. ( Reminder) Car was a 318/904 trans 7 1/4 rearend now has 360 w/bored 30 over,purple+cam & Modman 2x4. 904 trans. Leaf springs only.

 

[Treblig]

Ok, I finally got a chance to re check here is what I found out.............. The Transmission output is 1 Degree down. rear Pinion is 3 1/2 Degrees Down. And , Rear end is off center 1/2 to 3/4 of a inch towards passenger side. ( Reminder) Car was a 318/904 trans 7 1/4 rearend now has 360 w/bored 30 over,purple+cam & Modman 2x4. 904 trans. Leaf springs only.

Trans 1 degree down, pinion 3 1/2 down sounds pretty close to what it needs to be. When you accelerate the pinion should come up about 3 degrees putting the pinion at 1/2 down but you really need 1 degree up during acceleration. Left to right centering (from what I have read) shouldn't make any difference. Does everyone else agree???????

If there is no vibration under normal operating conditions then the angles are correct.
If there is vibration under acceleration, you need to add more downward pinion angle preload. If the opposite occurs, the vibrations tends to decrease or disappear under acceleration, you need to reduce the downward angle preload.

If the vibration steadily increases with driveshaft speed (either accelerating or decelerating) the symptom is primarily the result of a driveshaft imbalance or yoke runout. Sometimes this yoke runout problem can be improved by rotating the U-joint 180-degrees in the rear end differential yoke.

Driveshaft-related vibrations usually occur at roughly engine speed in high gear. Wheel/axle vibrations usually occur at 1/3 rd engine speed or driveshaft speed because of the differential gearing. To determining whether it is the output of the transmission or the pinion in the differential, change gears when the noise occurs and maintain speed. If the vibration/noise changes in frequency, the source is in the transmission or engine. If the frequency remains the same it is a driveline problem.

treblig

 

[beanhead]

Trans 1 degree down, pinion 3 1/2 down sounds pretty close to what it needs to be. When you accelerate the pinion should come up about 3 degrees putting the pinion at 1/2 down but you really need 1 degree up during acceleration. Left to right centering (from what I have read) shouldn't make any difference. Does everyone else agree???????

If there is no vibration under normal operating conditions then the angles are correct.
If there is vibration under acceleration, you need to add more downward pinion angle preload. If the opposite occurs, the vibrations tends to decrease or disappear under acceleration, you need to reduce the downward angle preload.

If the vibration steadily increases with driveshaft speed (either accelerating or decelerating) the symptom is primarily the result of a driveshaft imbalance or yoke runout. Sometimes this yoke runout problem can be improved by rotating the U-joint 180-degrees in the rear end differential yoke.

Driveshaft-related vibrations usually occur at roughly engine speed in high gear. Wheel/axle vibrations usually occur at 1/3 rd engine speed or driveshaft speed because of the differential gearing. To determining whether it is the output of the transmission or the pinion in the differential, change gears when the noise occurs and maintain speed. If the vibration/noise changes in frequency, the source is in the transmission or engine. If the frequency remains the same it is a driveline problem.

treblig

Yes...final angle under power..if the trans is 1° down(this doesn't change) the pinion should be 1° up under power.. to acheive this set the pinion down 2° if you figure it will climb 3° under power. As far as side to side our engines/drivelines are off-center, but the rear chunk makes up for that difference as the driveline doesn't hit the exact center of the rear allowing the axles to be the same length on both sides (treblig that's a good way to isolate a drivetrain vibration too!)

 

[va-mopar]

Thanks' all. I agree, setting the pinion down 2 degree's . And under power it will climb 3 degrees putting the pinion at + 1 degree counter matching the -1 degree of the transmission angle. Thanks' every one. Yea, The rear end chunk was set up with all new posi and new 355 ring and pinion and the noise was at any speed / as soon as you started accelerating . Thanks' again.

 

[oldkimmer]

If the noise is at any sort ur gears are not set up correctly. U don't want the pinion up +1 if ur tranny is at -1. Then ur up 2 degrees on acceleration. U want the angles to cancel out , not counteract. So what I'm saying is that if the tranny is -1 u want the pinion down -1 under hard acceleration. So set the pinion to -3 or -4. Kim

 

[va-mopar]

If the noise is at any sort ur gears are not set up correctly. U don't want the pinion up +1 if ur tranny is at -1. Then ur up 2 degrees on acceleration. U want the angles to cancel out , not counteract. So what I'm saying is that if the tranny is -1 u want the pinion down -1 under hard acceleration. So set the pinion to -3 or -4. Kim

Here is the whole story.. The rear end was set up the first time and then one of the bolts in the pinion yoke was broke off, so the pinion was removed and another was installed. Then the rear was put together and put under car. Then it was driven and a noise on acceleration and deceleration was heard. was told the pinion nut was too lose so nut was tightened, and noise on deceleration stopped but noise on acceleration was still noticed. was told the rear needed to be re-setup. It was, and put back in and driven and noise on acceleration was still there. So, I took it apart again and took it to be re-re-setup. It was and put back in and same thing.. Noise on acceleration. So , I re checked the pinion angle and it is -3 degrees. The noise must be in the rear-end, because Before putting this 8 .75 rear in car it had the 7.25 rear in and driven a little while with NO noise.

 

[va-mopar]

And yes every time I checked pinion angle car was (Loaded) on all 4 wheels.

 

[oldkimmer]

Then u should be ok on pinion angle. When they re set it up did the change the pinion depth or just the back lash? Do u have any pics of the patterns. Kim

 

[va-mopar]

Then u should be ok on pinion angle. When they re set it up did the change the pinion depth or just the back lash? Do u have any pics of the patterns. Kim

Was told that from second re-setup to third the pattern and back lash was changed. no pic's

 

[cawley]

I'm a tempting to set pinion angle on my 70 Duster. Any help/ advice would be greatly appreciated. It was a 318 with 904 trans and 7 1/4 rear. I put in a 360 and a 8 3/4 rear. It still has 904 tranny. I just took angle off tailshaft and it is. 1 degree down. What should the pinion angle be. The rear end don't have perches , so I will be weilding them on after I set the correct angle. Thanks in advance.

In my chassi book they say 5-10 nose down but prefer 5-7

 

[va-mopar]

Update, I got the car back in shop. Just out of curiosity and some extra time, I just pulled the 8 3/4 rear out. I put the 7 1/4 rear end back in. And measured the pinion angle and found it to be set at +3 ( 3 degrees up ). I got a set of 3 degree pinion shims and out of curiosity put them under the front of the 8 3/4 and rechecked the pinion angle, it is now at 0 degrees. I put everything together and took the car out for a short test drive. I found out that the noise it was making was still there BUT one half to 2/3's as loud. Maybe I going the right way with pinion angel. ??? I didn't re-check the transmission angle.

 

[Treblig]

Did you try this method while you were out on the road??
If there is no vibration under normal operating conditions then the angles are correct.
If there is vibration under acceleration, you need to add more downward pinion angle preload. If the opposite occurs, the vibrations tends to decrease or disappear under acceleration, you need to reduce the downward angle preload.

This way you know which way to go.

Treblig

 

[va-mopar]

Did you try this method while you were out on the road??
If there is no vibration under normal operating conditions then the angles are correct.
If there is vibration under acceleration, you need to add more downward pinion angle preload. If the opposite occurs, the vibrations tends to decrease or disappear under acceleration, you need to reduce the downward angle preload.

This way you know which way to go.

Treblig

I hear what your saying Treblig. the noise was at any speed, while accelerating . example- While doing 45mph, coasting no noise, if you press on gas pedal ,even just enough to stay at 45 noise, and pretty loud. I have a blt 360 with dual 3in exhaust that dumps right in front of rear end. and the pinion angle was at 3 degrees nose down.

 

[furyus2]

I think the op was right about keep going the same direction with the pinion angle. If you moved it up, and it improved, move the pinion up a few degrees more, and see if it keeps improving.

 

[va-mopar]

I think the op was right about keep going the same direction with the pinion angle. If you moved it up, and it improved, move the pinion up a few degrees more, and see if it keeps improving.

I agree, I'll keep moving it a few degrees at a time one way then the other to see if I can get it right. As always, Thanks Guys for your advice. I keep up dating till it's fixed.