65 SF rear axle pinon angle?

[James Romano]

While doing some work on the rear, I found that this unit was worked on and when reinstalled, was tilted about 15 deg nose down, which wore out the U-joint and destroyed the two clamps. Thankfully, nothing else.

What is the correct angle...or eyeball. I think I have it right, it's level and about 5 deg nose up. The drive shaft is straight as far as I can tell

Picture shows the right brake assy and the pinion before I took it all apart. See how far the whole unit is tilted...was a really poor install.

Thanks! Stay safe!
JR

 

[rkrochen]

I may be wrong but if memory serves correctly it should be between 5 and 7 degrees. I am sure someone else can confirm.

 

[Kram Edyorloh]

If that car is jacked up using the rear axle something is wrong there. To check it, the jackstands must be under the axle and not the frame. Its usually around 5* down but that alters under load if the springs are weak. It should never go up past straight in an ideal World, snubbers to the rescue!! LOL

 

[James Romano]

Right now, the car is on jackstands via using the frame right in front of the wheels. I have new springs and shocks

So you're saying put the axle on the jackstands then check? So how do I set this correctly if the axle is sitting on the jack stands? I won't be able to turn it. I can say for sure that it was definitely too far down... the collar bolts for the u-joint were bent to hell from the stress.

 

[James Romano]

I may be wrong but if memory serves correctly it should be between 5 and 7 degrees. I am sure someone else can confirm.

That would make sense... I'll go with that. I'm a little high now, so I'll see if that's better.

Thanks!

 

[Ross Wooldridge]

Essentially, it needs to be the same number of degrees OPPOSITE to what the tail stock and slip yoke are doing at the trans end. The degrees need to cancel themselves out for the U joints to work properly. I.E. if the slip yoke sits 3 degrees up above level, then the rear has to point down the same number of degrees. All of this needs to be done with the car's weight on the suspension.

Another way to look at it is to draw two lines - one showing the line coming straight out from the rear, and the other coming straight out from the slip yoke. They need to be parallel.

If your car has worn out the rear U joint, bent the clamps etc, more than likely the bushing in the tail shaft is worn out too.

Typically, because the engine is slightly tilted downwards from front to back, the rear points up slightly, and yes, typically between 4 - 7 degrees.

 

[James Romano]

Thanks for this. When I built my Jeep, I pretty much eyeballed it and allowed for a little flex when I lowered the body back down. But that was a lot easier because I have a 3" lift and don't need to jack it to get under it.

It looks like I had the third picture in your diagram... the bushing seems ok, no play at all in the tail shaft, it's tight. I think the u-Joint took the brunt of it.

What I'll do it raise the front up higher on jacks... set the pinion, lower it down and see how it looks and adjust from there.

Thanks for the info. I have it around 5* up right now... I'll let you know how it goes.

 

[Kram Edyorloh]

I'll make this easy, put the car on a 4 poster ramp so weight is on the car, you can not check pinion angle if the weight of the car is not on the axle.
Then you put an angle finder on the top of the diff housing and read it, it should be 5* down.
You correct it by putting shim wedges between the spring and the spring perch.
If its waaay out ....and yours looks like it is....you have to cut the perches off, rotate the axle casing and tack weld back on, remove and weld fully.

 

[Kram Edyorloh]

The "axle" means axle/diff housing over here. What you call an axle is called a half-shaft over here so maybe the terminology isn't helping LOL

 

[Ross Wooldridge]

Correct - diff and axle housing.

 

[Kram Edyorloh]

You NEVER want 5* up on the diff when the vehicle is static , that means under acceleration the propshaft will be starting to pull the yoke out of the tailshaft, the diff slams UP under accel not down.....hence a snubber to restrict it.

 

[James Romano]

I'll make this easy, put the car on a 4 poster ramp so weight is on the car, you can not check pinion angle if the weight of the car is not on the axle.
Then you put an angle finder on the top of the diff housing and read it, it should be 5* down.
You correct it by putting shim wedges between the spring and the spring perch.
If its waaay out ....and yours looks like it is....you have to cut the perches off, rotate the axle casing and tack weld back on, remove and weld fully.

OK, got it. Makes sense now. I've been doing more reading and I understand what you mean now. I'll do that today and see where it's at. I also found this on ebay, which matches what you are saying... not so much the product... but his description and pics are very good. I'm really getting schooled on this car... lol.

eBay

 

[Kram Edyorloh]

Has that car got the springs removed in the pic?, I cant see them, it looks like the axle (casing) is just hanging there?.....my eyes aint what they used to be though LOL

 

[James Romano]

I'll make this easy, put the car on a 4 poster ramp so weight is on the car, you can not check pinion angle if the weight of the car is not on the axle.
Then you put an angle finder on the top of the diff housing and read it, it should be 5* down.
You correct it by putting shim wedges between the spring and the spring perch.
If its waaay out ....and yours looks like it is....you have to cut the perches off, rotate the axle casing and tack weld back on, remove and weld fully.

It was really bad with the old spring in... now with the new setup, it's just about level, so I think I can get away with using a shim.

 

[Kram Edyorloh]

Its all good my friend, i have been messing with these cars 40years and still learn something now and again, we never stop learning, which is good

 

[Kram Edyorloh]

This was my 300 in the late 80's/90's, because it was so low the prop was actually straight and parrellel with the road, static!......but we didn't care back then and regularly hit 120mph up the motorway 6 up, good times back then, today, not so much

 

[James Romano]

Lol! Yeah....I had my Dad's workhorse as my first car. 73 Ply Fury Sport Suburban. Banana yellow with fake wood paneling. Hahaha. Loved that car... Made a great bed in the back for the babes. Lol

Here is the current angle... I'm going to get some shims and just level it out. Will be miles ahead of what it was, which was really bad

 

[James Romano]

First photo is tilted a little too much, use floor as a reference

 

[Kram Edyorloh]

Thats more like it mate, as you say, its still up a bit, it needs to be around the same amount DOWN. Just jack it up under the centre of the axle so its just about ready to take the weight off the stands and thats what the car sees-ish when driving, if you want you cant chuck a bag of sand or two in the trunk to simulate passengers but that is considered over the top in reality, it moves all over the shop under real time use....but HAS to be restricted to some degree.
A friend of mine left the U bolts slack after fitting an axle in a ;72 Charger, first pass down the strip when he lifted at the end the casing rotated and pulled the prop out over the finish line at 110mph.....it was not a pretty sight, took out the trans,floor,brake pipes,cables, everything.

 

[Ross Wooldridge]

Nice to know that eBerg is selling shims. Thanks for the link. I'd love to get that pinion angle gauge he has!!