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How big can you go on shims?

Desert Rat

Desert Rat

Fetch the comfy chair
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Got the front and rear drivelines in but my angles are off. Here is the stats:

Front - 6 inch TC springs on a D60. Measurements are:
TC =4 degrees up
Driveshaft =24 degrees down
Pinion =5 degrees down

Anybody proficient on calculating what shims I need for the front?

Rear - Corp14ff on 4 inch ORD shackle reversal, 4 inch TC springs, 1 inch ORD zero rate.
TC=4 degrees down
Driveshaft=24 degrees down
Pinion=13 degrees down

According to several articles, I'm supposed to subtract 2 degrees for axle wrap in the rear. So, my calculations show I need an 11 degree shim in the rear to put it 2 degrees low which levels it out under load and keeps the pinion in line with the driveshaft. The driveline is a 1350 CV from High Angle Driveline. I have an e-mail into Jesse too. So, is an 11 degree shim too much? I really don't want to cut and re-weld the spring perches. I also sit 1 inch high in the rear right down which I had planned on leaving so that after loading the rig with gear it would sit level. If I pulled the zero rate, it would sit level empty. However, this would probably reduce my angles a bit. Recommendations? Anybody else in this boat before? Looks like JKW Offroad makes 10 degree shims now and can custom makes some 11's for me.
 
the proper way to figure the size shims is to measure the center line of the axle to the ujoint, and the driveshaft length.

this will give you a ratio, of every so many pinion angles changes, the driveshaft will change 1 degree.

on my front axle, i had a 15* ujiont angle, pinion length was 15" and the driveshaft was 34" (IIRC), so preaty much for every 2.6 degrees the pinion changed, the driveshaft changed 1 degree. i only needed a 6* shim to make a 0* ujiont angle.

i found a good right up while i was looking at the shims that explains this quite well, ill see if i can find it again.
 
I have 12 deg in the rear. no real problem with me. Unless you didn't allow for your drive shaft travel.
 
I suspect that I will have to have the driveshaft lengths changed when this is all done anyway since rotating the pinion up is going to compress my slip shaft a bit both front and back.
 
There is a good article on Pirate also about driveshafts, specifically the 1350 HAD one that I bought. As long as I am ok with running a 11 degree shim in back, I'll be good to go. I'm thinking though that if I pull the 1 inch zero rate, and then add a shim back in , I won't lose the full inch of lift, more like 3/4 of an inch only. That would also lessen my angles. The hard part is figuring out how much the driveshaft will raise when I rotate the pinion up. Right now, 11 degrees is what I need, but that isn't taking into account the reduction in angle on the driveshaft as it lifts with the rotated pinion. I've read a couple of articles and one said it didn't make a big difference. The other article said it was a large difference and screwed up his calculations.
 
what are the lengths of the driveshafts and ill figure up the size shims you need, im bored.

there is a guy on pirate that is making 15* shims also if you need them.
 
I'm running 8 degree shims in the front and no shims in the rear.
 
I`am running 8* steel shims in the rear to bring my pinion down from the 4" flip and longer shackle`s. But I also have the short shaft kit with new 1350 CV`s.
Put alittle weld on them and you are good togo.
 
Didn't measure the lengths of the shafts. I used an angle finder to find my angles ala the Pirate article that BillaVista wrote. I double checked the stats I posted above and they are accurate. No doubt I need an 11 degree shim in back, but perhaps a tad smaller since if I rotate the pinion up, the driveshaft is going to come up a little too. And, I'm thinking of pulling that zero rate which would lower the back an inch but come up slightly with the shim.
 
In order to get your spring plate bolts into the housing on the passenger side the third shim will go under the top spring plate. And it should be turned the opposite way of the bottom.

(hijack begin) Does anyone make offset pinion degree shims (zero rate style) like the ones Az-Kickin' made? Or has anyone had there zero rates milled to a degree? (hijack over)
 
If you check out the product reviews on the main CK5 page for the High Angle Driveline 1350 shaft, you will see that they took a set of ORD zero rates and had them milled to a 6 degree taper.
 
Update:

Ok, so I go out tonight and pull the zero rates out. I put everything back together and the Blazer is pretty much sitting level now instead of a bit butt high. I drive it around the block and then take the angle measurements again. Wow! a whole one degree difference. I was hoping pulling the zero rate would bring things a little better in line. Not so. I had a good conversation with Jesse at HAD and he is recommending I cut the spring perches off and have new ones welded on instead of using 10+ degree shims. He knows his stuff and looks like I'll probably take his advice. Sucks though since I thought I was almost done......
 
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