[SoCal805]

I am planning on lowering the rear 2 to 2 1/2" (blocks come in various sizes)

For those who have installed them, did you use angled shims to restore DL/Pinion angle?

Like these

https://www.speedwaymotors.com/Leaf-Spring-Pinion-Angle-Shims,3354.html?sku=916433-2

or did you shim tranny mount?

 

[ilikeike]

I've shimmed both.

Right now I just have a 1/4" spacer at the trans. mount.

Adding angle shims will add a little to your lowering block drop also,so take that into account when your adding blocks.

 

[SoCal805]

Yeah the wedge shim would add some to the block height. I was going 2 1/2" block but would likely do 2" if using the shim.

Raising housing 2"+ would have to effect DL angle so you would want to nose pinion down to compensate and or raise rear of tranny

I did a auto to T56 swap on my Impala (96) which was never made as a stick car by GM. DL angle was what I had to restore. Used 2 GM shims (1/4" total) under tranny to bring DL angle back to what it was as a automatic car

I would think several people have done lowering blocks with leaf so ideally they can share some 411

 

[69L48Z27]

You can also get blocks with some angle built in. Use the Tremec mobile app to get everything dialed in.

 

[SoCal805]

to lower the nose of the pinion when adding lowering block, does the thick side go forward or back?

under or above the lowering block?

https://www.speedwaymotors.com/Leaf-Spring-Pinion-Angle-Shims,3354.html?sku=916433-2

 

[schnide]

Thick end of shim to the rear to point pinion nose down. Most guys suggest to get 2 additional shims and install them on the bottom side with the thick end the other way to keep the "spring pack" parallel.

I suggest you do yourself a favor and measure your driveline angles before you make any changes incase you end up with any issues. Lower the car then recheck your angles and adjust from there.

 

[SoCal805]

Thick end of shim to the rear to point pinion nose down. Most guys suggest to get 2 additional shims and install them on the bottom side with the thick end the other way to keep the "spring pack" parallel.

I suggest you do yourself a favor and measure your driveline angles before you make any changes incase you end up with any issues. Lower the car then recheck your angles and adjust from there.

If using the shims do they go on top, or under the lowering block?

I assume top

10/4 on measuring DL angle pre and post lowering block install. Familiar with the process. It very well may be not ideal now so I was going to check that anyway.

It's a 2" drop and IDK yet if I will even need the shims but ordered them in case I do when installing the 2" lowering
block

I have single spring leaf

 

[schnide]

I would put the shim on top of the lowering block, that way the angle of the shim tilts the rear end without tilting the block which would move the rear forward as well as tilting it.

I actually made my own lowering blocks with the angle milled on the top for that same reason.

 

[68lowered]

I'm not sure why you're adding shims as these would change the pinion angle. When I put my 4 link in, I measured the angle of the transmission output shaft and set the pinion so they were at the same angle. This is how they set the angle from the factory, so if you had a shim in the original, I would think you'd still need one with lowering blocks. Lowering blocks are rectangular, so shouldn't change the pinion angle. They change the height of the pinion instead, so your driveshaft might end up being a bit too long.

 

[SoCal805]

I'm not sure why you're adding shims as these would change the pinion angle. When I put my 4 link in, I measured the angle of the transmission output shaft and set the pinion so they were at the same angle. This is how they set the angle from the factory, so if you had a shim in the original, I would think you'd still need one with lowering blocks. Lowering blocks are rectangular, so shouldn't change the pinion angle. They change the height of the pinion instead, so your driveshaft might end up being a bit too long.

Assuming my DL angle is in spec now, I will still measure it and see and use that 411 as a base to compare what it will be when I "lift" the rear axle housing (pinion) to lower the car

My understanding is when you move the rear end up/down for any reason, like lowering block, that changes the rear pinion angle and thus its comparison to the tranny/yoke angle. If without a shim I am good, fine I was just assuming though that a 2" lift of the rear end would change the DL angle

I will measure with just the blocks and see. If I need to get the pinion nose down some because it was raised, the shims will do that.

 

[SoCal805]

UPDATE:

Installed 2" blocks with a 2 degree Pinon shim. DL angle is good and no vibes at 90 mph

Doing RideTech coils up front for a 1 1/2" drop. Also A arm bushings. All other front suspension has been replaced (Moog)

Car was stupid high in back so needed a little more drop in back than front

Stengel Bros. U bolts were plug & play, no drilling, 7/16" x 3 1/16" x 7 7/8"

Used Energy Suspension leaf spring isolators