Pinion angle question

-
If you check any rear end, you'll find they are between 3* - 5* up in relation to the pinion center line. There's nothing "arbitrary" about it. That's just where they all are. I prefer 5* simply because that's a little more conducive to a performance rear suspension, but anywhere between 3-5 is acceptable.
 
RustyRatRod said:
If you check any rear end, you'll find they are between 3* - 5* up in relation to the pinion center line. There's nothing "arbitrary" about it. That's just where they all are. I prefer 5* simply because that's a little more conducive to a performance rear suspension, but anywhere between 3-5 is acceptable.
Click to expand...

You're right - Stock A body housings put the pinion at a 5 degree upward angle relative to the perches. But if everything is loose, why not just wait til everything is in and get actual measurements to put the pinion angle exactly where you want it? It's the same amount of work at that point.

I guess he could always set it to stock and adjust with shims if absolutely necessary. But at that point, it's probably splitting hairs anyway for a cruiser.
 
mopowers said:
You're right - Stock A body housings put the pinion at a 5 degree upward angle relative to the perches. But if everything is loose, why not just wait til everything is in and get actual measurements to put the pinion angle exactly where you want it? It's the same amount of work at that point.

I guess he could always set it to stock and adjust with shims if absolutely necessary. But at that point, it's probably splitting hairs anyway for a cruiser.
Click to expand...

He can. Certainly he can do it either way. It's just this old dude's opinion that it's easier to get to out from under the car, that's all.
 
But consider this. When it's in the car, how do you know "where" the perches are in relation to level? You're going to have to move the rear axle out of the way anyway to level up the springs where the perches sit, so why not throw it on the blocks like I described? It's just easier all the way around, IMO. Not that it amounts to much.
 
RustyRatRod said:
But consider this. When it's in the car, how do you know "where" the perches are in relation to level? You're going to have to move the rear axle out of the way anyway to level up the springs where the perches sit, so why not throw it on the blocks like I described? It's just easier all the way around, IMO. Not that it amounts to much.
Click to expand...
Yea I agree with you I was looking at it again and the perches are nowhere near level. I reentered it took some more measurements for my backplate to perch and I'm just take it back out and put it on blocks and level i just didnt want to pull it back out that sucker is heavy and I'm on the dirt so there is no sliding or rolling it. Its pulling and tugging and lifting haha
How about this? Just brain storming. Say I measured the degree of the leaf spring where it meets the perch. Let's say its 4 degrees from level. Couldnt I just add that 4 degrees to the 5 and set it at 9 degrees?
 
I just took some measurements and the perches are at about 5 to 6 degrees the front being upward so at this couldn't I just set the pinion level at zero. That would be the same thing as the perches being level and the and the pinion being 5 degrees correct? Or am I thinking about it backwards?
 
dartfreak75 said:
So I need to mock up my ubolts bolt everything together and lower it down check it again. Ok thanks I'm gonna have to get my tires on my rims then lol
Another question my leaf springs move side to side about a 1/2 inch or so is it ok to push them over as far to the center as I can to help with tire clearance or will that cause wear on the bushings and springs?
Click to expand...

If your springs are in the stock locations, the perches need to be 43" center to center. If you push them in narrower, you'll put a bind on the springs. If you want them in further, now would be the time to install a 1/2" offset kit and weld the perches in at 42" c-c.
 
dartfreak75 said:
I just took some measurements and the perches are at about 5 to 6 degrees the front being upward so at this couldn't I just set the pinion level at zero. That would be the same thing as the perches being level and the and the pinion being 5 degrees correct? Or am I thinking about it backwards?
Click to expand...

The problem with that is, "where" are the leaf springs? Are they at full droop? Also, is the frame of the car level? There are way too many variables IMO to do it in that way.
 
Needs complete drivetrain to get it right. Loaded suspension.
I prefer to level the driveline-motor and trans.

RRR, its always been my understanding pinion points down a couple degrees when its all said and done.

i use the tremec app with my cell phone,jury is still out as i havent moved mine any further than shed to shop.
 
Tooljunkie said:
Needs complete drivetrain to get it right. Loaded suspension.
I prefer to level the driveline-motor and trans.

RRR, its always been my understanding pinion points down a couple degrees when its all said and done.

i use the tremec app with my cell phone,jury is still out as i havent moved mine any further than shed to shop.
Click to expand...

Yes, that's AFTER it's installed and in relation to the transmission output shaft. But as for installing spring perches, the pinion center line points UP.
 
RustyRatRod said:
Yes, that's AFTER it's installed and in relation to the transmission output shaft. But as for installing spring perches, the pinion center line points UP.
Click to expand...
Seems like a crapshoot. I did set up pinion level, measured angle of perch,so i could install new perches on a different diff. That worked out, as i just copied original angle.
 
RustyRatRod said:
The problem with that is, "where" are the leaf springs? Are they at full droop? Also, is the frame of the car level? There are way too many variables IMO to do it in that way.
Click to expand...
Yea the leafs are at full droop the car is all the way up on blocks and the rear end is setting suspended on the leafs.
I'm just thinking outloud so feel free to correct me if I'm wrong but if I do it the way you said and put the perches level and the pinion 5 degrees up wouldn't that be the same thing I'm just using the leafs to suspend it instead of blocks ? Please dont take this as arguing or disagreeing I'm just trying to learn lol my brain is melting trying to figure out these damn angles
 
I just drew it out and I'm backwards. If the perches are level and the pinion is at 5 degrees then you put the pinion level the rear of the perches would go up! Right now my perches are at 6 degrees with the back down so I I need to set the pinion at 11 degrees. 6 to level the perches and 5 to get my pinion angle. Correct?
 
dartfreak75 said:
Yea the leafs are at full droop the car is all the way up on blocks and the rear end is setting suspended on the leafs.
I'm just thinking outloud so feel free to correct me if I'm wrong but if I do it the way you said and put the perches level and the pinion 5 degrees up wouldn't that be the same thing I'm just using the leafs to suspend it instead of blocks ? Please dont take this as arguing or disagreeing I'm just trying to learn lol my brain is melting trying to figure out these damn angles
Click to expand...

No, because the springs need to be at ride height and the frame level before any measurements are taken.
 
RustyRatRod said:
No, because the springs need to be at ride height and the frame level before any measurements are taken.
Click to expand...
I still don't understand why it would matter if you weld the perches on the axle while its setting on blocks the ride height isn't coming into play either if its suspended on the leaf springs or suspended on blocks level is level I dont understand the difference. But I trust you and trust your opinion so I will pull it back out and do it on blocks
 
If you just slam don't want to pull it back out, here's how to do it. Center the rear end as I described above. Install the U bolts and shock plates and torque them to spec. 45 LB FT. Support the car by the rear axle housing in the rear and the lower control arms in the front. In other words, on the suspension. Level the frame rails front to back and side to side.

Now, Put your angle finder on a known dedicated parallel surface to the pinion center line. I always turn the yoke so the u joint saddle is vertical and put the angle finder on the bottom and straight with the car's center line. Take a look at the reading.

Now, get your floor jack and place it under the rear end center on the housing behind the yoke so as not to disturb the angle finder. Just lightly bring the jack against the housing. Just enough to hold it up, because you're fixin to loosen the shock plate nuts.

Now, loosen the shock plate nuts just enough so you can rotate the housing to achieve the correct reading on the angle finder. The reading you're looking for now, it NOT 3-5*. It is whatever the transmission output shaft is, but in the opposite direction.
 
RustyRatRod said:
If you just slam don't want to pull it back out, here's how to do it. Center the rear end as I described above. Install the U bolts and shock plates and torque them to spec. 45 LB FT. Support the car by the rear axle housing in the rear and the lower control arms in the front. In other words, on the suspension. Level the frame rails front to back and side to side.

Now, Put your angle finder on a known dedicated parallel surface to the pinion center line. I always turn the yoke so the u joint saddle is vertical and put the angle finder on the bottom and straight with the car's center line. Take a look at the reading.

Now, get your floor jack and place it under the rear end center on the housing behind the yoke so as not to disturb the angle finder. Just lightly bring the jack against the housing. Just enough to hold it up, because you're fixin to loosen the shock plate nuts.

Now, loosen the shock plate nuts just enough so you can rotate the housing to achieve the correct reading on the angle finder. The reading you're looking for now, it NOT 3-5*. It is whatever the transmission output shaft is, but in the opposite direction.
Click to expand...
I'm just gonna pull it out and do it the way you said better safe than sorry I don't want to do this twice lol
 
dartfreak75 said:
I'm just gonna pull it out and do it the way you said better safe than sorry I don't want to do this twice lol
Click to expand...

While doing it "the other way" is more complex, it does make sure that you will not have to run shims under the spring perches to change the pinion angle. Doing it "my way" means there is margin for error there, but nine times out of ten it's either dead on or very close.
 
RustyRatRod said:
While doing it "the other way" is more complex, it does make sure that you will not have to run shims under the spring perches to change the pinion angle. Doing it "my way" means there is margin for error there, but nine times out of ten it's either dead on or very close.
Click to expand...
I'm gonna get my old rear end and measure it and see where it was just to double check. As long as it's not terribly off I dont see it causing a problem I have shims tho if i need them i bought them when i did my shackles like 19 years ago because i was told i would need them and i never used them lol
 
dartfreak75 said:
I'm gonna get my old rear end and measure it and see where it was just to double check. As long as it's not terribly off I dont see it causing a problem I have shims tho if i need them i bought them when i did my shackles like 19 years ago because i was told i would need them and i never used them lol
Click to expand...

That's a SMART idea. In fact, I would be confident enough to match that rear end, because it was likely right.
 
I didnt even think of it until a few mins ago. It would have been smart to measure it before I took it out with it hanging on the springs and I could have just matched that number lol lesson learned.
 
dartfreak75 said:
I didnt even think of it until a few mins ago. It would have been smart to measure it before I took it out with it hanging on the springs and I could have just matched that number lol lesson learned.
Click to expand...

Yeah, you could have done that. lol Just set it up on blocks like I told you to do the other one and measure it. Then you'll have something to go by. But you'll still have to yank the other one back out to set it up like you measured the original one.
 
RustyRatRod said:
Yeah, you could have done that. lol Just set it up on blocks like I told you to do the other one and measure it. Then you'll have something to go by. But you'll still have to yank the other one back out to set it up like you measured the original one.
Click to expand...
Yea that's what I will do. That will be a perfect time to measure the difference in length of the pinions and housing too so I can know how much to shorten my driveshaft
 
You must log in or register to reply here.
-

Back
Top