Outer Limits 4x4 Board

I'm about to set the pinion angle on my buggy, but I don't know too much about it. I know pinion angle needs to be within about 5 degrees, but I don't know much else about it. if you have any links to websites or just information about it could you please let me know.
thanks in advance for your replies.

Golden rule (theory) is that the output of the drive shaft (pinion end) must be parallel with the input (transfer end). This will ensure that the variations in velocity across the non constant velocity joint (uni) will cancel each other out...and ultimately negate any vibration.

Truth is that with some you can get away with it and with some you can't.

If the driveshaft angle is steep then a little pinion angle will go along way to reducing the angle and will benefit from a more direct drive as well as reducing uni stress and wear. Also because it will be predominently a low speed vehicle then vibration caused by possible misalignment is not a major issue.

Finally...if it is the front axle then pinion angle can be critical as it will denote your castor angle and can greatly affect your steering.

Pinion angles.

Pinion angle

HSV Rangie has the theories right. However, I do know that on the early Bronco bobtails, which had an upper CV joint and the pinion in line with the drivshaft, when those CV´s wore out, many guys just put in a traditional single U-joint and lengthened the driveshaft, instead of replacing the grotesquely expensive CV. Few ever complained of vibrations.
Never, ever turn up your whole front axle to let the pinion meet the driveshaft angle: Negative caster is a disaster.
It´s not that complicated to loosen up the knuckles on the axle and turn the axle without altering the caster.
Any workshop worth it´s salts should be able to do it. If your working with an older vehicle it may be set uo with zero degrees caster. In that case it would be a good thing to work in some caster once the axle is in pieces. 4 - 5 degrees is about right. Of course the more caster you´ve got, the heavier the vehicle will be to stear, (hardly noticeable with 4 or 5 degrees and power stearing) and more willing to right itself out of turns. If the vehicle is a strict rock crawler that hardly ever is driven on roads, zero degrees is ok. It´s always a compromise. I had a CJ5 ´55 once, no caster originally, in which I built in 5 degrees and that was the straightest going car I´ve ever had; I could drive far over the speed limit and take my hands of the wheel; that thang just went straight down the road, while other, compairable jeeps were dancing all over the place at far lesser speeds.
It depends on what the vehicle will be used for, as always!

HSV Rangie wrote:Pinion angle

What about broken back set up. (mine works a treat.
HSV Rangie You can do the pic

With UJ's both ends of the drive shaft (no cv or double cardin joint), if the angles are not equal (as in the 2nd pic), the velocity of the UJ's will be out of phase and not cancel each other.

However, rovers point the pinion of the front diff up and rotate the UJ's in relation to each other so that they do cancel.

Some info to read:

http://www.pirate4x4.com/tech/billavista/PR-shaft/

Michael.

been wondering for a while when you lift the pinion (diff) up to setup a Double Cardain joint like in the pic above... wouldnt the pinion bearings in the diff then starve for oil?

Ryan wrote:been wondering for a while when you lift the pinion (diff) up to setup a Double Cardain joint like in the pic above... wouldnt the pinion bearings in the diff then starve for oil?

Just found out all about that! My set up is like the double cardin pic. My pinion bearing is now growling. An extra litre of oil and a tube of Moly Bond has done a good job of quietening it done, but damage is done so it wont go away totally.

I pointed the Surf down a steep bit of drive and also drove up some car ramps to lift the rear higher so I could get the oil in.

You could also top up through diff breather too but then you dont know where the levels are at.

Does any one know what would happen with tooooo much diff oil??? Just an over flow up the breather??

Cheers,

Alec

Surfin Alec wrote:

Ryan wrote:been wondering for a while when you lift the pinion (diff) up to setup a Double Cardain joint like in the pic above... wouldnt the pinion bearings in the diff then starve for oil?

Just found out all about that! My set up is like the double cardin pic. My pinion bearing is now growling. An extra litre of oil and a tube of Moly Bond has done a good job of quietening it done, but damage is done so it wont go away totally.

I pointed the Surf down a steep bit of drive and also drove up some car ramps to lift the rear higher so I could get the oil in.

You could also top up through diff breather too but then you dont know where the levels are at.

Does any one know what would happen with tooooo much diff oil??? Just an over flow up the breather??

Cheers,

Alec

you would start getting oil up the axle tubes rather than in the centre bottom, and would cause the axle seals to blow out and u would get diff oild leaking down the back of your tyres

Why does that cause the axle seals to blow out if there is a breather? I assume they just leak?

Im just about to do a flip arm on my 80 so that i get my castor back...

I already have a D/C front shaft...

When the diff gets rotated back to its original positon will the front shaft vib???

And will the angle on the uni bee too much???

It has a 7" lift..

READ THE TECH ARTICAL ABOVE.

Michael.

Soas long as it has no mre than 3 degrees it wil be right??

does this stil apply fr the d/c..