Driveline Angles

[eric8]

I've read several articles detailing LS swaps in our truck that talk of putting a protractor on the new tranny to ensure the 3 degree downward transmission slant. Most of these swaps are using the swap plates that keep the engine in the same placement as the OE sbc engine. I'm wondering, if this is the case, what is the need for checking that angle? The engine shouldn't have moved right? And I've seen none of them mention checking the angle and it being off after the swap. If this were the case, how are they fixing it?

[brad_man_72]

You'd fix it by shimming the back of the transmission.

[solidaxel]

So how much shim would 1/8 be in degrees. or 1/4"?

[BR3W CITY]

Depends where you measure from.

The first problem is that some folks don't use an angle finder, and try to do it off of another surface, like the frame, or even the ground which usually isn't level. The other problem is that they place the angle find on a non-flat plane, altering the "True" angle of the engine and trans.

With the truck level'd out, placing the angle find somewhere like the valley pan usually works well. Using the shims on the trans xmember or mount (I've seen both done) will lower the angle, and usually you'll be working backwards like that. Its much less common to dry fit everything, then have to increase the angle unless a very non standard combo of parts is used.

If my very crappy math is right, it should be about 1/4 spacers should get 1.2*, assuming that the length from mounting to mounting is about 36"....