Setting Driveline Angle Subframe as Reference?
 

Can I go off of my factory subframe as a reference and set the angle of my engine and transmission outside of the car?

I need to fabricate a transmission mount for my LS1 T56 combo in my '69 Camaro and I was wondering if I can just go off of the subframe for now? What I plan to do is favor it more downward in the rear so I can just make some spacers to put under the transmission mount if I need to raise it a bit when it's actually installed under the car. I'm figuring this whole operation would be really easy to do at the moment since the subframe (though I will probably be getting a replacment sub) is out of the car.

So, if this isn't a dumb idea....If I level the sub frame rails, what angle should the motor and trans be at? In other words, what angle should the motor and transmission sit at in relation to the subframe?

Thanks!

Kinda hard to start playing with angles before you know what your rear's pinion angle will be also. I'd wait on measuring and trying to determine angles until everything is installed and your car is sitting at its final ride height and weight. Then measure your angles on your rear and trans and determine what needs to change. I run leafs and used some angle shims under the leaf perches to get the rear angle just how I wanted and then made a spacer out of a chunk of aluminum to put under my trans mount to get that angle set also.

Using stock ride height and body bushing height with a stock suspension front and rear, shouldn't there be a "stock" angle to the subframe?

Yeah, I realize I'll have to tweak it a bit when everything is installed but say I make the transmission mount on the crossmember 1" lower than where it would sit at the "stock" angle. Then after I get it together I can put in the correct height spacer....maybe it will be 1.125, maybe .9375....to fine adjust the car. I need to fabricate the entire transmission crossmember and it would be a whole lot easier out of the car.

Basically, I'd like to know what the angle "should" be in reference to the subframe and then I'll fabricate the crossmember so the angle is too great without a spacer.

Does that make sense?

Thanks!

I believe the stock angle in these cars for the engine/transmission pointing down with the subframe installed and the car level is 4 degrees, but don't quote me on that. Some searching on the net could verify. I don't know if the subframe is perfectly level with car itself, but I think it is or is very close. Maybe that 4 degrees is a point of reference you can work from. You mentioned you plan to point your rear pinion down, so I'd play with some different numbers to ensure you can make that work before setting engine/trans angle in your subframe. My setup worked best with my rear pinion pointed up 2 degrees and the engine/trans pointed down 2 degrees. Had to raise the trans mount quite a bit(and 'massage' the tunnel) to get that engine/trans angle. Plenty of folks using rear pinions down also. Best of luck. :thumbsup:

Thanks, I've been searching the net but haven't come up with anything in relation to the sub frame. Since there are so many different stances out there I just need a point of reference and the sub frame would be best since it's separate and takes care of both the engine and transmission mounts.

What I was talking about was pointing the trans down with the initial xmember/trany mount fabrication so that I could always just space it upwards to bring it where it needs to be. I have no idea where I'm going to put the rear pinion angle yet other than it's stock location for the moment.

The following statement is from Inland Empire's Power Train Setup documentation posted on their web site.

"Engines are set in the frames at 3 degrees downward angle to the rear. This is virtually a world standard for engine placement and is the basis for intake manifold construction. It is this fixed installation that determines the possible. To arrive at equal and opposite u-joint angles the pinion must be set parallel to the crankshaft."

Actually you might want to read the entire document as it also talks about engine placement in the frame.

http://www.iedls.com/asp/admin/getFi...&TID=28&FN=PDF

Yes, 3* downward is ideal, but you may not be able to get there without modifying the tunnel. I've seen 4-5 degrees used by some because if you angle it up any more, the trans can hit the tunnel. The further you get from 3* the more likely you'll be to have unwanted vibrations.

Thanks everyone for your replies. The .pdf file linked to be TheJDMan looks particularly helpful.

I believe that with my engine mounts I should be able to get to 3 degrees without transmission tunnel surgery since when I had the engine mocked up it looked good but we'll see.

I'm still trying to figure out what to do for a subframe at the moment since I've decided that mine is junk.

I may be going with an aftermarket rear suspension sooner than later as well which should make adjusting my rear pinion angle much easier.