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8* at 4.5" lift dose this sound right

B

bcredxj

NAXJA Forum User
Location
coquitlam b.c.
I am running a 242 aw4 with a re hack & tap, the longest xj front drive shaft to a 8.25 on 3" leaf pack with 1.5 shackels and I need 8* of shim dose this sound strange to any one else or is that about right.:confused:

I have 16* on the drive shaft and 86* on the back of the dif cover bolts
 
8* does sound like quite a bit, especially seeing that you have 1.5" lift shackles installed as well. The shackles by themselves should already help to get the pinion up a little. Also remember that as soon as the pinion lifts the angle on the propshaft will reduce, but not necessarily in direct relation to each other. I don't think this is an exact science and some trial and error might be needed to get you angles within spec - saying that, I'm sure the amount of degrees the propshaft angle will be reduced by lifting the pinion a certain number of degrees could be calculated, but my maths is a bit lacking, so I won't be able to help you on that one.

When I was at that amount of lift the longer 1.5" shackles I had in was enough to get my angles to such a point where I didn't have any vibrations (I'm also running the RE hack & tap SYE).
 
best way to tell is buy a 15 dollar angle finder and do some simple math. you want 1-2*... i'm sure you know the tolerance, though.
 
At 6" of lift, I ran a 4* shim and a 1.25" lift shackle, and had no vibes.. this is before I went SYE.
 
Where did you get 16* and 86* from? Was that measured with an angle finder? If so, to get within 1-2* you would need 10-11* of shim unless I'm doing my math wrong... Sounds like too much.
 
fyrfytr1717 said:
Where did you get 16* and 86* from? Was that measured with an angle finder? If so, to get within 1-2* you would need 10-11* of shim unless I'm doing my math wrong... Sounds like too much.
Click to expand...

i'm thinking they're degrees from horizontal. and if that's the case, your math is correct. that's a LOT of shim.
 
Sounds like a lot of shim to me. I ran 4* shims with 4" and 6" of lift and didn't have a problem with either combo.
 
measuring the driveshaft with a angle finder I have 16* from horizontal and on the diff I am measuring off the back bolts on the diff cover and I am getting 86* from vertical and the shackel took off 2*

math 90-86=4 (diff) 16-4=12 (axil-diff)
2-12=10 (shackel - over all)

so from 8*-10* am I right????:roll:
 
I'm no pro at this (I'm just about to order my first new driveshaft/shims) but I would guess that you don't get to factor in any additional amount for the shackles if they were already installed at the time you took your angle measurements.

I understand how they help out your pinion angle a degree or two by lowering the rear eye of your leafspring, but if the shackles were in place when you measured 86* & 16*, then 86* & 16* is your final measurement. This results in 10*-11* of shim for your ideal driveshaft angle.

Now if you haven't installed the shackles yet and are planning on installing them at the same time you install the shims, then yes, I think subtracting 2* would be a safe guess. However, I'd just install the shackles and take another measurement to be sure.
 
Good to go! :thumbup:
 
bcredxj said:
measuring the driveshaft with a angle finder I have 16* from horizontal and on the diff I am measuring off the back bolts on the diff cover and I am getting 86* from vertical and the shackel took off 2*

math 90-86=4 (diff) 16-4=12 (axil-diff)
2-12=10 (shackel - over all)

so from 8*-10* am I right????:roll:
Click to expand...
Don't measure the driveshaft. You should compare the output angle at the t-case, compared to the pinion angle. The t-case measurement is toughest as there is no clear-cut place to measure. Your measurement will be somewhere less than 10* off vertical.

Use the machined surfaces for the rosette welds to the left and right of the rear cover for the axle measurement.

The difference between those two is what you should shim. I'll work up some graphics later if there's still any question. The driveshaft angle is irrelevant, since the operating angle of the u-joint is what matters.

Jim www.yuccaman.com
 
Okay -
jeep_angles.jpg


The two measurements that matter are highlighted, and neither of them has anything to do with the angle of the driveshaft.

Jim www.yuccaman.com
 
OK, now I'm confused. Admittedly I'm a total newb when it comes to this stuff, but I think this depends on the type of driveshaft you are using.

If it is a single cardan driveshaft, then yes I agree you want to get your transfer case and differential at the same angle in order to share the deflection evenly between the u-joints at the transfer case yoke and the differential yoke.

However, if it is a double cardan driveshaft (which the front XJ driveshaft in question is) then you want your driveshaft angle to be within 1*-2* of your differential angle. This allows the u-joint at the differential end to have minimal deflection while the majority of the deflection is absorbed by the double cardan joint.

According to the Tom Woods website in regards to aligning your driveline after installing a SYE kit:

"With this conversion you should be able to keep the transfer case at stock height. You will however, want to be sure to pitch the differential so the pinion points more or less directly at the out-put of the transfer case, maintaining a minimal joint angle at the differential end."
 
fyrfytr1717 said:
OK, now I'm confused. Admittedly I'm a total newb when it comes to this stuff, but I think this depends on the type of driveshaft you are using.

If it is a single cardan driveshaft, then yes I agree you want to get your transfer case and differential at the same angle in order to share the deflection evenly between the u-joints at the transfer case yoke and the differential yoke.

However, if it is a double cardan driveshaft (which the front XJ driveshaft in question is) then you want your driveshaft angle to be within 1*-2* of your differential angle. This allows the u-joint at the differential end to have minimal deflection while the majority of the deflection is absorbed by the double cardan joint.

According to the Tom Woods website in regards to aligning your driveline after installing a SYE kit:

"With this conversion you should be able to keep the transfer case at stock height. You will however, want to be sure to pitch the differential so the pinion points more or less directly at the out-put of the transfer case, maintaining a minimal joint angle at the differential end."
Click to expand...
Dangit - Through all that I missed one key point....original poster has a hack-n-tap SYE. Yes, the angle of the pinion would therefore point 1-2* below the driveshaft to allow for axle wrap.

The measurement in the pic I posted is just for the stock driveshaft.

Jim www.yuccaman.com
 
Glad to know I wasn't misleading bcredxj. I still learned something new though. I knew you wanted your pinion yoke 1*-2* below the driveshaft, but I didn't know that was to make up for axle wrap. Always good to know the reasoning behind the rules of thumb. :thumbup:
 
SO am I doing this right or
p176534_image_small.jpg
p176535_image_small.jpg


should it be measured like this this
jeep_angles.jpg

remember this is a double cardan front drive shaft for running in the back:doh:
p176534_image_small.jpghttp:
 
Just for a quick recap...

SYE w/ double cardan: Measure driveshaft angle and differential pinion angle. Driveshaft angle should be 1*-2* steeper than differential pinion angle. (I believe this is what you are doing in your pictures.)

Stock single cardan: Measure transfer case angle and differential pinion angle. They should be the same. (This is what is shown in the diagram.)
 
fyrfytr1717 said:
I understand how they help out your pinion angle a degree or two by lowering the rear eye of your leafspring, but if the shackles were in place when you measured 86* & 16*, then 86* & 16* is your final measurement. This results in 10*-11* of shim for your ideal driveshaft angle.
Click to expand...

Well, now that I have my SYE installed and am trying to correct my driveshaft angle, I have found that the info I gathered from others and repeated above is not completely accurate. It is still true that you want your driveline angle 1-2* steeper than your your pinion angle however, simply substracting one angle from the other doesn't give you the right amount of shim as gorman pointed out in the following quote...

gorman said:
Also remember that as soon as the pinion lifts the angle on the propshaft will reduce, but not necessarily in direct relation to each other. I don't think this is an exact science and some trial and error might be needed to get you angles within spec - saying that, I'm sure the amount of degrees the propshaft angle will be reduced by lifting the pinion a certain number of degrees could be calculated, but my maths is a bit lacking, so I won't be able to help you on that one.
Click to expand...

In my case, I have a measurement of 5* on the pinion and 17.5* on the driveshaft. After accounting for the 1-2* this leaves me with a difference of approximately 11*. I'm going to see if I can work out the math, but I'm figuring that shimming half that amount is probably about right as the driveline will get flater as the pinion angle gets steeper. I'll report back if I figure out an equation to use.
 
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