Pinion, cut n turn Q (1 Viewer)

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

Joined
Feb 21, 2004
Threads
73
Messages
597
Location
The Rockies or the Andes
On an SOA if I move my pinion farther "forward" than I do down, is a cut and turn still necesary?

i.e. I am SOA now but I also reversed the front springs and added a Toybox. The pinion is now so far from the t-case it looks like I'll need the rear DS from a 60. The case is at 2 degrees from vertical, if i set that on the front pinion and allow a degree or two for the axle to torque under load i end up with a pinion that is vertical (straight up and down, 90 degrees) which is, I beleive, what the stock pinion angle is. I am not trying to avoid a cut and turn, i am just wondering if it is necesary.

Am I missing something here?
 
don't measure pinion angle just yet....first step is to set your caster angle at ride height, then see how the pinion angle ends up....

stock caster is +1....big tires like more caster, so plan on +4 or so....unless yer only running 31's on that SOA ;)
 
When people do a SOA they usually have a lot of travel and scary driveline angles so they need to a) point the pinion at the transfer case (i.e., tilt it up so that it points directly at the Transfer case) and b) get a CV driveshaft (the one with a double u-joint bulbous at the T-case end). This solves the angle problem but by tilting the pinion at the sky you make your caster angle worse (to improve caster on the front of a 40 tilt the pinion DOWN) – to solve BOTH of these issues people with initiative and a few hours usually do the cut and turn (cut the axle ends through the first section of pipe and rotate the ends so that you actually improve the caster from stock -- to compensate for large tires)
 
IanB said:
On an SOA if I move my pinion farther "forward" than I do down, is a cut and turn still necesary? SOA is a way of adding lift and bigger tires for more clearance. One thing that is a clearance issue is the pinion. By pointing it at the t-case you remove more of this issue but create others. Your caster will be way off. If you are adding bigger tires then you want more castor like Woody stated. In order to do this without cut and turn you are dropping your pinion even more and can cause binding issues with the pinion. BY doing a SR you are moving the pionion up but IMO not enough to disregard a C&T. You can get by but your already have to take the axle off for the spring swap why not just spend a little more time and do it right.
i.e. I am SOA now but I also reversed the front springs and added a Toybox. The pinion is now so far from the t-case it looks like I'll need the rear DS from a 60. The case is at 2 degrees from vertical, if i set that on the front pinion and allow a degree or two for the axle to torque under load i end up with a pinion that is vertical (straight up and down, 90 degrees) which is, I beleive, what the stock pinion angle is. I am not trying to avoid a cut and turn, i am just wondering if it is necesary. With a Toybox and that long of a DS you might not but by adding the castor correction I think you might run into more clearance issues with the pinion than if you did a C&T. Best advice is to buy a set of castor shims and see where the pinion sits and how it performs offroad. If you get binding you will know it one way or the other.

Am I missing something here?

My Opinion
 
Trollhole said:
My Opinion


Good stuff. I am trying to talk Uncle Ben into helping me set the caster angle, he has a caster/camber gauge.
 
My front DS angle is not steep at all due to the Toybox and spring reversal, so if I rotate the pinion to point at the t-case I dont gain a lot of clearance at all. Should I rotate it anyway to prevent bind or should I set it to the same angle as the output flange on the t-case to prevent DS vibration?
 
if you do C&T which I say go ahead and do, point the pinion at the t-case, ground clearence is good, you won't notice vibs from the front end. My axle isn't turned much either, 4.5deg for caster, and 7deg up from pinion, that is only 11.5deg
 
The stock caster range are from .84 to 2.34º + in my 60 axles .. I thought are the same range for all Cruiser axles ..

After my SO I try to go over 3.50 but somhing in my idea fail and keep under 3 both sides .. :(
 
The stock caster range are from .84 to 2.34º + in my 60 axles .. I thought are the same range for all Cruiser axles ..

After my SO I try to go over 3.50 but somhing in my idea fail and keep under 3 both sides .. :(
 
I am still undecided about this. The front output flange on the t-case is 2 degrees from vertical, pointing up, not down at the diff. If I set the exact same angle on the pinion so the u-joints are in sync I end up with exactly +4 degrees of caster. So, theoretically I don't need to c&t except for the potential for bind (edit: and clearance). Since the front driveshaft will be long and at a shallow angle I need to figure out how to figure out if a driveshaft I dont have yet will bind. Clear as mud? :D
 
IanB said:
On an SOA if I move my pinion farther "forward" than I do down, is a cut and turn still necesary?

i.e. I am SOA now but I also reversed the front springs and added a Toybox. The pinion is now so far from the t-case it looks like I'll need the rear DS from a 60. The case is at 2 degrees from vertical, if i set that on the front pinion and allow a degree or two for the axle to torque under load i end up with a pinion that is vertical (straight up and down, 90 degrees) which is, I beleive, what the stock pinion angle is. I am not trying to avoid a cut and turn, i am just wondering if it is necesary.

Am I missing something here?
I sketched it out on graph paper. Move the T-case back 6" from the toy box install. Move the pinion down 5" from the SOA. The driveline/pinion angle is reduced.
And yes the Front DS is a longfeller. :grinpimp:
 
I even had Uncle Ben scratchin his head over this one. Basically the trade off now is between clearance and having a u-joint only DS in the front with the joints in the correct plane. Im still thinking, i can definitely understand the clearance gain but then I create DS issues. With mods its always a trade off it seems.
 
rusty_tlc said:
I sketched it out on graph paper. Move the T-case back 6" from the toy box install. Move the pinion down 5" from the SOA. The driveline/pinion angle is reduced.
And yes the Front DS is a longfeller. :grinpimp:

Front springs are reversed too, so like a 3" gain there? Not sure, wheelbase is 98.25 inches.
 
For future reference, the combination of H42/Toybox/Split case with reversed stock 40 springs and SOA will damn near fit the stock rear DS. We were sizing it yesterday. I want a DS with a lot more travel in the splines though so I wont use it.
 
Ian, you don't really need to cut n turn from what you describe. can you take a pic of the front DS angle for us?
 
Mace said:
Ian, you don't really need to cut n turn from what you describe. can you take a pic of the front DS angle for us?

ditto ..

CV.JPG


transfer.JPG
 
Ok here it is. Angle of output flange of t-case, angle of pinion and caster. It didn't come out super clear in the pics but teh protractors both read 88 degrees (same plane) and the caster gauge reads 4 degrees.
PICT1031.JPG
PICT1030.JPG
PICT1027.JPG
 
Last edited:
I mocked up a DS with duct tape and welding rods from center to center. It's about 3.5' long with the front axle weighted. Although the rods sag a little bit its still safe to say teh DS is pretty close to 10 degrees from horizontal, with no sag it would be less, maybe 9 degrees? For reference the axles are all level, side to side and front to back, so this is just as if the rig was sitting on level ground.
PICT1032.JPG
PICT1033.JPG
 

Users who are viewing this thread

Back
Top Bottom