Driveline Angles - Diagram Attached - getting ready to buy some shafts

[joshd1971bronco]

Here's my measurements for my rebuild (see diagram). I took all measurements on a level surface, the tub is on the frame (though the top isn't on and the interior isn't in).

I am running a 302, an NP435/205 with a custom crossmember, and the factory LP dana 44 front and 9 inch rear.

What do I need to consider when buying shafts or having custom ones built.

Are my angles bad enough to need shims in the rear? What do I do about the front?

Thanks for any info.

 

[surveyor5]

My recommendation is to put a 6* shim at the rear axle. Angle at the front axle is extreme also.
Mike

 

[joshd1971bronco]

Well, I just got off the phone with Wild Horses. And, I have yet another glowing review to write about them. I spoke to Nick: extremely nice, willing ot help / talk and answer questions. I went over all my measurements with him.

Long story short, I'm getting a 24.5 inch front driveshaft and a 32.5 inch rear drive shaft (level one, $259 each). When I asked him about the angles, he said they weren't that bad and everything should work just fine (especially since I am not doing any EXTREME wheeling or have massive amounts of articulation).

I asked him about total driveline angles and what is considered 'acceptable'. He said that up to 30 degrees generally works okay. When you get over that, things start to bind, you need shims, or you should consider other means to correct the issue.

So, I'm gonna try them without changing anything and see how they do.

 

[surveyor5]

My recommendation is to put a 6* shim at the rear axle. Angle at the front axle is extreme also.
Don't know if you have 6 or 7* C bushings there already. If not they are in order!
Mike

 

[garberz]

That's too much of a difference for the rear u-joint to last. The rear pinion angle needs to be 1-2 degrees less than the drive shaft for the u-joint to properly rotate. So like surveyor5 suggested 6 degree shims will get you in the ball park. I would figure your rear pinion angle later after you get some weight in it, bumpers, spare tire, fuel tank. The front isn't as critical, with that low angle you probably already have 7 degree bushings, which makes for better caster. The front is always a trade off between caster and u-joint bind. That's why guys rotate the yokes to correct caster and keep a decent pinion angle up front.

 

[garberz]

Thinking about your pinion angle on the rear. It's very low, you really shouldn't need shims with a 3 1/2" leaf pack. Is the rear end stock? Are the springs on backwards? I measured my 76' and my angle is 16 degrees. 3 1/2" leafs. Just curious as tho why yours is only 8 degrees.
Mark

 

[joshd1971bronco]

Regarding the rear, I sure don't think I've put the leaves in backwards. But, I'll do some double checking if that truly sounds odd.

It is the stock '76 ford, low pinion, 9-inch rear end.

Now, I'll say this, I have yet to drive the truck or anything (it's going through a frame off rebuild) so there is a possibility that things aren't quite 'seated' or settled in I suppose. I did bolt things up pretty tight though.

So, do most agree that my rear pinion angle should be more like 16 degrees rather than 8? I'm not opposed to running shims if that's an issue.

Oh, and I think I have the 7 degree C bushings in the front already.

 

[garberz]

Hopefully others will comment on this. I'm not sure how much more the rear will squat with more weight, and if it squats more, the pinion angle won't change hardly. Even the driveshaft length should be good if it squats a bit more. I'm going to see what others say, and tell me your springs are oriented right.

 

[JSmall]

Hopefully others will comment on this. I'm not sure how much more the rear will squat with more weight, and if it squats more, the pinion angle won't change hardly. Even the driveshaft length should be good if it squats a bit more. I'm going to see what others say, and tell me your springs are oriented right.

My pinion is at 10* and DS is at 20* with a 2" lift block. I bought some spring perches to fix the difference in angle.

 

[bknbronco]

Front angles dont matter since you have lockouts. Just get the caster correct.

Rear mave sure your getting a cv joint in the driveshaft. As far as shims (24-8=16) so id get some 12 or 14deg shims made. Id recheck your angles. I have a 5.5" lift and my rear is 27deg on the shaft and 18deg on the pinion (but thats with a 4deg shim already in there). I just had 10deg shims made so well see how that works for me.

 

[POOH BEAR]

How are you measuring the degree's on the shafts? I always wondered.

 

[JSmall]

This is the method I used.

http://www.stu-offroad.com/axle/pinion/pinion-1.htm

 

[joshd1971bronco]

Holy cow - someone dug up an old post! ; )

To measure the angles, I used one of those cheap angle finders from the hardware store. They usually have a magnet on one side. Just set it up against whatever you're wanting to measure and let the needle stop moving.

I did notice that my u-bolts weren't all the way tight on the rear and that if I tighten them up it should bring the rear pinion up some decreasing the angle between teh pinion and the drivehshaft which will help. I might still need to add some shims. We'll see what she measures at after she's all done and loaded down.