Rear driveshaft angle ?

[DEEPWOODS]

My rear drive shaft has more angle now with the longer 4R70W and Np205,yoke flange to yoke flange is 28 3/4" the drive shaft is at 21 degrees and the pinion 14 degrees Is this bad? Thanks Keith

 

[bax]

Put the pinion in line with the driveshaft. line them up any you will be good. You can be down a few degrees.

 

[DEEPWOODS]

If I am doing this right my pinion it 7 degrees lower than the drive shaft Is this OK for highway?

 

[COBlu77]

If I am doing this right my pinion it 7 degrees lower than the drive shaft Is this OK for highway?

I doubt it, but you'll know pretty quickly when you get it on the road. It will vibrate like crazy and you'll go through u-joints pretty quickly. The pinion angle is supposed to be 0-1 degrees.

I used 6 degree spring shims, and I'm at about 2 degrees. You're really supposed to weld on new spring perches at the proper pinion angle. The angle on the CV joint is supposed to work up to 22 degrees. Mine is about 18. What you should really check is your front DS and see if it's binding now. My CV will bind at full droop. That's a much tougher issue to solve.

 

[DEEPWOODS]

My front driveshaft is longer than stock about 4" and lower at the TC because the front yoke of Np205 is a little lower also. I have the 90's explorer front drive shaft cut down in the front .Some one on here said the explorer front driveshaft has more angle than his new tom woods driveshaft

 

[bax]

take a picture of what you have.

 

[kaw550]

Wouldnt he need a 4 degree shim?

 

[Broncobowsher]

NP205, CV yoke or U-joint yoke?

 

[DEEPWOODS]

NP205 with CV yokes

 

[Broncobowsher]

Wouldnt he need a 4 degree shim?

That sounds about right. Currently a 7° angle at the pinion, but the shims yield more gain then there actual taper due to the pinion raising up and taking out some of the driveshaft angle in the process. So a 4° shim should yield 5°, maybe even a little closer to 6° or so of pinion angle correction.

 

[beaux312]

Not tring to hijack this, but my d/s angle is 23 and pinion is 13 what size shim should I use?

 

[Broncobowsher]

Not tring to hijack this, but my d/s angle is 23 and pinion is 13 what size shim should I use?

That is a 10° operating angle. I would look for a 7 or 8° shim, min 6° to put in there.

It is real easy, you want a little less shim then the angle you are trying to fix. There are ways to use math to figure what you really need, Really just a little compund geometery. The length of a few of the arms of the angles gets a bit tricky as does using an imagenery piviot point and a few other odds and ends. In the end it isn't super critical anyway so if you are off by a degree or two it generally works just fine.

 

[DEEPWOODS]

I have 6° shims now at the rear axle springs and only 2 1/2" of lift but the transmission and NP 205 take away about 4" of length, So this is why I am having a problem. If I use more shim to rotate the axle up will I have pinion bearing lubrication issues for highway use?

 

[bax]

No, you will be fine on the highway.

 

[Broncobowsher]

I was running 10° of milled lift block (actually a little too much, didn't factor that pinion rise, shallower driveshaft angle then I took measurements). That was on 3½" of lift and about 3" shorter driveshaft due to the 4R70W. 4.88 gears made that shaft spin mighty fast. I drove it from Phoenix to Vegas a few times, lots of other highway driving as well. Some small towing jobs; all the gravel to landscape the back yard 1½ times (mistake in planning), hauled tons of dirt out of the backyard (part of that planning mistake plus puttin in a pool), and even some high speed runs doing 80 running late to meet up with people for a trail run. The pinion bearing oiling was fine. Biggest issue was having too much oil in the diff due to the high fill plug location, lost a couple axle seals right away. After fixing the oil seals and setting the correct oil level (just to the bottom of the axle tube) it was fine and happy for years. Sold it and as far as I know it is still happy.

 

[DEEPWOODS]

So,do I pull the 6° shims and change to 10° or 12° ? Will this change my drive shaft length a little shorter about how much or not enough to worry about?

 

[Broncobowsher]

It will have a minor change to driveshaft length. It should not be enough to matter. If it does, then it wasn't right to start with.

 

[Steve83]

It may be too late for this, but if you're interested, this is how Ford recommends setting up a driveshaft:

 

[DirtDonk]

I only looked at the pics Steve, but does it say anything about double-cardan shafts in the text? I'm thinking no, since the later Broncos probably didn't use them anymore (that right?) and so might not be covered in the TSB. If they did though, I'll go back and read the whole thing just for the info.

Thanks

Paul

 

[HGM]

I only looked at the pics Steve, but does it say anything about double-cardan shafts in the text? I'm thinking no, since the later Broncos probably didn't use them anymore (that right?) and so might not be covered in the TSB. If they did though, I'll go back and read the whole thing just for the info.

Thanks

Paul

**Paul,
The idea with a double cardan is to "split" the angle. If you have a 8* angle at the trans, you could use the double cargan to give you an operating angle of 4* for each joint in that double cardan joint.. ** This info may not be 100% correct.. I'm learning a bit more about the double cardan here.. I've recently found this quote:

Since a double cardan or CV driveshaft cancels out the angles on that end, you need to set it up so the non-CV end operates at 0 degrees. It's as simple as setting it up so the pinion is in line with the driveshaft. In reality, we've found that on leaf-sprung vehicles, it's best to set the pinion 1-3 degrees lower because the pinion will climb under load. Vehicles with link-type suspensions can set the pinion to 0 degrees

.... So, it may have a little more to it than a 2-pc design would...
On a live axle, live Steve's TSB shows, you want an operating angle of at least 1/2* in order to assure needle bearing rotation. But, you want to keep that angle to less than 3* for maximum life.. In the world of lifted, short wheelbase, Bronco's, thats not always possible.. The most important thing is that the operating angle of each joint is as close to equal as possible and the shaft is in phase. This way, each rotation of each yoke variation will cancel itself out..

BTW, simply changing pinion angle will not always correct the issue.. The pinion angle is dictated by the transmission output shaft angle.. They should be on the same plane, or a D/C joint will be needed to split the front angle to get them close..

I'm a bit surprised though that true CV joints are not more popular.. They can be built to be pretty strong and they do not have speed variation when the angle changes, hence the name constang velocity.. Ford experimented with these on the Bronco II and everyone uses them on FWD as well as 4x4 half shafts..