Need advice on driveline angles

[69importkilla]

I did some measuring and here's what I came across:

Transmission is pointing down 5 degrees
Driveshaft pointing down 3 degrees
Pinion pointing down 2 degrees

Now by all means I can imagine this being not right. My understanding is, the transmission should be parallel to the pinion, and they ideally should be less than three degrees.

I also noticed the input side of the transmission has some play. Whats acceptable if any?

Now how do I fix it? I cannot move the transmission up, short of cutting the tunnel up. Its really, really close to the bottom of the tunnel as it is. Also heard some comments on using a CV joint on the front part of the shaft, any opinions?

Should I try to put some taper shims in rear spring mounts to bring the pinion up some?

Thanks for the help

[19,69camaro]

What about motor mounts? Do you have clearance under the oil pan? To me 5 degrees sounds like a little much and I think you will run into trouble later with header collector clearance.

I think you are on the right track with starting with the rearend, but I think you will have to adjust the engine/transmission angle to get everything where you want it.

[RobNoLimit]

Where are you measuring the trans angle? Most trans pan rails are not on the same line as the output shaft. The oilpan rail on the motor is a good spot. Also, is the suspension at ride hieght?

[69importkilla]

I dont have a heck of alot of clearance under the pan, so moving it down could be difficult, but maybe not impossible.

I am measuring the transmission angle on the yoke itself (hopefully thats legit). The transmission doesnt have any flat rails on it to utilize. The suspension is at ride height.

[69importkilla]

Anyone?

[darrinf68]

If my calculations are correct you have a 2 deg angle at the trans (5 down trans minus 3 down driveshaft) = good. However, the angle at the pinion is 5 deg (3 down driveshaft + 2 down pinion) = bad. Those angles need to be equal or no more than 0.5 diff otherwise you'll have vibration. 5 deg down at the trans seems a bit much. Most are around 3 deg if measured at the flywheel, at least on a stock setup. The transmission and pinion do not necessarily need to be parallel, rather the angles between them at either end of the driveshaft should be equal. But don't take my word for it:
http://www.iedls.com/asp/admin/getFile.asp?RID=5&TID=28&FN=PDF

[rustomatic]

Darrinf68: Thanks for the helpful post/link--after a year, my laziness in setting up this angle properly has really gotten the best of me. It's time to tear everything apart again anyway, though...

[69importkilla]

+1 for me too. Thanks to Darrin! Thats some useful information.

Now the only thing I'm worried about is the angle of the motor/transmission. Its going to take some work to get it right. Still I wonder if/how a CV joint set-up would work? Anyone gone that route yet?

[darrinf68]

Are you using the stock subframe? I don't know about a T-56, but I had to cut out the top of the tunnel on my 68 to fit a TKO600 - that's with a Heidts subframe though. The bottom of the oil pan is about 1/4" from the steering rack so there's no way to lower the engine in front. If I didn't open up the tunnel, the drive train angle would have been about 5.5 degree down at the flywheel. Two degrees may not sound like much, but at the back of the transmission that's about 2" difference. I now have 3 degrees at the flywheel and about 2.5 degrees down at the pinion. At ride height the driveshaft is damn near level. Of course I had to make my own crossmember to make all this fit, which is another story in itself.

[69importkilla]

Yeah I'm using a stock subframe. I am going to have to look at remounting the engine to get this stuff right and/or cutting the tunnel up. Neither idea is something Im looking forward to. I am going to get some shims to move the pinion up a bit and hopefully that will hold for a bit. I guess this is why I'm beating the idea of the CV joint. If it is capable of rectifying the issue without move the engine and tranny around that would be even better...