Mort

Is the fat end of the 2* shim on the 1500 spring pack facing the front of the truck? I think it is but couldn't tell for sure. If it is then take the shim off and that should fix your pinion angle. Then I think your pinion face would be 92* ( 2* up) and your rear drive shaft would be 95* ( 5*down). Net pinion angle should be 3* negative which should be good for your application. It will depend on how much your axle rotates upward under acceleration. With the torque you are/will be putting through your drivetrain I would try to get the pinion angle a little more in line and -3* sounds like it would be a good place to start.

I think in theory you will get some good weight transfer but I would be afraid of wheel hop. Time will tell and I hope it hooks like stink.

moregrip

iTrader: (8)

the fat part is in the front.

After further reading there are a few things bothering me.
1st, it seems there should be about a 1* difference between the trans angle and the front drive shaft angle, they are on the same plane. Apparently to activate the needle bearings in the u-joint a 1* difference is needed. I suppose if I was splitting hairs there might be a .5* variance.

If that's the case, then maybe lowering my carrier bearing would be a better choice. I can increase the trans/front d/s variance and decrease the diff/rear d/s at the same time.

Just got back from a test loop. Rides like a dream, fantastic. Absolutely zero traction. No vibrations up to 75mph. Still, I'm not comfortable with the pinion angle.............

Mort

Needing a 1* variance in the joints to activate the needle bearings is news to me. If so maybe you are better off dropping the carrier bearing a little to achieve the best driveline angles. You will just have to figure out how much of a shim it will take and if the studs on the carrier bearing are long enough to accommodate the shims.

Zero traction on street tires = and

Well the ride sounds good.

Hopefully the slicks will hook.

moregrip

iTrader: (8)

I am going to put on a traction device at some point, just not exactly sure what. The Caltracs were just so damn noisy, I couldn't take it anymore.

I'm not sure what to do, time will tell I guess

moregrip

iTrader: (8)

I going to remove those shims this morning and re measure, that -6* is just bugging me too much

moregrip

iTrader: (8)

one side done, ****! It was almost harder to remove the damn shim than swap leaf springs! LOL.

BTW, earlier when I said they were 2* shims I was just guessing , when I finally got the shim out and took the time to read it, it was actually a 3.5* shim! says so right on the shim

moregrip

iTrader: (8)

Here are the final changes in ride height and driveline angles

Ride Height:
................................old.............1/2 ton susp...........1/2 ton susp
.................................................. .3.5* shim...............no shim
Driver Rear...............41 8/16.............40 1/16................39 11/16
Pass Rear.................41 13/16...........40 5/16................39 15/16
Driver Front............................................. ..................38 6/16
Pass Front............................................. ....................38 8/16

Basically the truck looks level now even though there is roughly a 1" rake to it.

.....................caltracs......unloaded.....1/2 ton susp.....1/2 ton susp
.................................................. ......3.5*shim............no shim

diff angle...........93*.............92*............90* ..................92*
rear d/s angle.....98*.............96*............96*...... ............95*
front d/s angle....95*.............93*
trans angle.........95*...........93.5*

pinion angle w/caltracs loaded -5* (diff 3* up)
pinion angle w/caltracs unloaded -4* (diff 2* up)
pinion angle 1/2 ton susp w/3.5*shim -6* (diff 0* up/down)

pinion angle 1/2 ton susp no shim -3* (diff 2* up)

moregrip

iTrader: (8)

the ride is sooo much better, glad I finally did this mod, no more traction, lol, no more noise either

so far so good on vibrations, none up to 90mph

BlownChevy

iTrader: (20)

I am glad you finally did A mod.

Mort

That -3* pinion angle sounds better.

Congrats and good work.

Now on to the next challenge. Traction

Maybe a few hundred pounds worth of sand bags in the bed will do the trick....