Rear Pinion Angle Off? Highway Vibes (1 Viewer)

[tsototh]

My truck has some vibes on the highway (above 60). It is SOA (was that way when I bought it) and has had the vibes since I bought it as well. I have felt the rear driveshaft and there is no play in the U-joints or the trans case output or the rear axle.

I haven't attempted to get the driveshaft balanced, but I have had the tires balanced. Anyway, to keep some of the mystery out of it, here is a photo. The angle is not parallel between the rear axle and the transfer case output, and it isn't quite a straight shot to the rear axle either (if that counts). And I don't think the driveshaft is out of phase, but will double check when there is more light out there (wouldn't that give me vibes at speeds other than highway anyway).

Opinions?

Thanks in advance, .

 

[Stumpalama]

Often, you need a Double Cardan shaft when the pinion is not parallel with the t-case output. Otherwise there are vibrations... I can't tell if you have one in your picture; it will be on the transfercase output. As well, if the pinion is set too high even with a DC shaft you can get vibrations.. that is my problem right now, bad geometry when I set up my SOA in the rear. Also, an anti-wrap bar is a good idea with an SOA. It prevents the springs from s-curving under load and stressing the pinion which can lead to it breaking.

-Stump

 

[GulfShoresFJ60]

Yeah, what does the other side of the driveshaft look like. That will help us answer the question.

 

[cruiserjunktion]

check the torque on the pinon nut

 

[Cruiserdrew]

Hang on here. We don't need to see anything else. Your pinion angle is WAY off. You choices are either parallel with a normal driveshaft or it points directly at the t-case. This one is neither.

This pinion angle is just all wrong. No amount of double cardan shaft is going to fix that.

You either need to shim the perches, or better, remove the perches and reweld them in the right place.

 

[rookie54]

Yes, this is all wrong in to terms of "drive line tech." If you want no vibes several things have to happen. The pinion angle needs to be corrected for either style of drive line first. An anti-wrap bar would help with a corrected pinion angle and it's worth remembering that under load(acceleration or sustained throttle) the pinion angle will change. If with you current setup you can point your pinion angle down enough to get parallel with the T-case and not have the u-joints bind then it should eliminate the vibes. Usually a custom CV rear drive line provides the best of both worlds; no vibes and good articulation without binding u-joints.

 

[clongacre]

best pinion angle is 5 degrees morethen angleon your engine cv driveshafts are a must

 

[tsototh]

I was thinking along the same lines. Cut the perches, turn the axle to be pointing straight in line with the driveshaft, and go with that. I'm thinking maybe the PO put it in this orientation (but not quite right obviously) rather than parallel due to the fact that the driveshaft may have not been long enough, especially at full droop. Either that or the U-joints may have been binding. Who knows...

So how much does a CV driveshaft cost? If I went that route, plus turned the axle parallel, then a anti-wrap bar... How much would all that cost? I am currently incapacitated and don't have a welder, or welding skills. I may have someone who could help me on turning the axle, but I'm not sure sure he could help on fabbing a anti-wrap bar. At least the vibes would be fixed! But I also want gears, and longfields, and polys.......

 

[lehiguy]

I was thinking along the same lines. Cut the perches, turn the axle to be pointing straight in line with the driveshaft, and go with that. I'm thinking maybe the PO put it in this orientation (but not quite right obviously) rather than parallel due to the fact that the driveshaft may have not been long enough, especially at full droop. Either that or the U-joints may have been binding. Who knows...

So how much does a CV driveshaft cost? If I went that route, plus turned the axle parallel, then a anti-wrap bar... How much would all that cost? I am currently incapacitated and don't have a welder, or welding skills. I may have someone who could help me on turning the axle, but I'm not sure sure he could help on fabbing a anti-wrap bar. At least the vibes would be fixed! But I also want gears, and longfields, and polys.......

The anti-wrap is not absolutely nesesary, but fixing that pinion angle should be considered as such. You need to get your hands on a angle grinder (cheap and easy, a 4 1/2" unit should suffice) and a new set of spring perches. Get the vehicle off of the wheels, take off the U bolts and cut off the existing perches with your angle grinder. Then place the new perches on the axle tube. Let the weight back down onto the axle and then use a jack or some other form of force to rotate the axle until you have the correct pinion angle which will be this; in agreement with the T-case out put flange minus two degrees, meaning two degrees lower than the front out put if you DO NOT have a CV joint on the front of the driveline. If you do have a CV joint on the driveline, the pinion should point directly at the T case output minus two degrees. The two degrees allows for the pinion rising under torque. Rent a welder or get a friend to help weld the perches on in the appropriate location.

 

[agent orange]

The pinion angle needs to be addressed as mentioned above but you should also check to see if the yokes are in phase.

 

[cruiser88]

The driveshaft is not in phase.....turn it around its backwards also

 

[tsototh]

Here's a better pic of the whole darned thing...

Looks to be in phase to me (unless I am thinking wrong). Also, as far as it being backwards, could that be a significant factor as well?

The front driveshaft is the stock variety (1 u-joint on each end) and the pinion is pointing towards the t-case as well.

Any more opinions? Thanks for all the comments thus far!

 

[Cruiserdrew]

Technically it is backwards but that won't affect the vibe thing. Generally, since the splines can be damaged by rocks, you want them up against the t-case where they will be out of the way. No big deal though. I run a DC shaft in the rear and the splines are down by the diff by necessity. Works fine.

The phasing looks right, but even so, your angles are just wrong. Whoever set that up just didn't know.

Either they are parallel and you run a "normal" drive shaft, or the pinion point exactly at the t-case and then your run a DC shaft with the DC at the Transfer end. There isn't a 3rd choice. Plus, yours has an added problem-under torque the rear diff wraps UP, making your crappy pinion angle even worse. You really should do this right.

Setting perches in the rear is about as simple as welding projects get. Get some of RuffStuff's perches and get to it!

 

[cruiser88]

ya the phasing is correct. When I got mine backwards there was a slight vib. but then again anything would make my old 62 vibrate.

 

[GulfShoresFJ60]

Yeah with that driveshaft the rear pinion flange should be parallel to the transfer case flange.

 

[tsototh]

Which is the better option? A DC shaft, or just put it parallel and keep my current one? Do you think my current one would be long enough being in a parallel position?

 

[Cruiserdrew]

Which is the better option? A DC shaft, or just put it parallel and keep my current one? Do you think my current one would be long enough being in a parallel position?

Personal opinion: I think the d/c shaft is better. The pinion is tipped up and out of the way. Down side is that it's much more expensive.

I used the front shaft from an 84 and had it lengthened to fit the rear. SOme minitrucks also have a nice DC shaft.

Here is the angle at the differential:

The important thing to see is the zero degree angle at the pinion.

 

[rookie54]

Maybe this can add as a "stimulus" but running the setup with the bad vibe can do some potential damage somewhere? Bearings, gears, seals....? input? The DC shaft setup is a proven winner. I would suspect a custom rear shaft be several hundred bucks at least. Where you at?

 

[weak-link]

try some steel shims, once you find what degree works tack them to your perches.

done-cheap-effective

 

[tsototh]

What about this guy?
https://forum.ih8mud.com/sale-parts/263869-front-double-cardigan-driveshaft-85-pickup.html

A 85 Mini-truck front driveshaft that has been lengthened a bit?

Would that work, what would it need besides possibly being lengthened? Not sure if the flanges are the same or not? Diff U-joints too?

Could go this route too, hard to tell if it is in bad shape or not, guess it would be cheap insurance to go ahead and change out the u-joints when I got it lengthened. Maybe talk him down in price too...

https://forum.ih8mud.com/sale-parts/247400-82-60-series-front-shaft.html