MG Sports Cars

OK, after some rest, I think I'm beginning to understand this. I read that the ideal engine angle is 3 degrees down. The best I can get is 4 or 5 degrees before stuff starts hitting stuff. So that tells me I need 5 degrees up on the pinion to get the driveshaft to 0 degrees.

Is that correct? Also, I am leveling the car using a jack for my degree measurements. the car actually sits lower in the front than back. Should I be measuring angles with the car level or with the car as it will ride?

Starting to have geeky fun with this now. :)

Using the side chrome strip as reference of zero degrees, the engine needs to be 3 degrees down at the back from this zero line (disregard any chassis rake). Once you have the engine/xsmn down at 3 degrees, the RA pinion needs to be pointing up by 3 degrees.
Edit: There is nothing magical about 3 degrees,.....it happens to be average for our conversions - if yours ends up at 2 or 4 or ?, you just need to match the pnion angle. The driveshaft angle is essentially immaterial at this point.

Here's a neat Harbor Freight digital angle finder that has a zero reference capability...had mine for years!




Edited 2 time(s). Last edit at 07/21/2014 09:07AM by ex-tyke.

Thanks Graham! That's exactly what I have been doing, using the body line to get the car level. I think 4 degrees is doable without the tranny running into the trans tunnel. I am having to fabricate a trans mount as all of the Ford ones are so tall that they push the transmission up against the tunnel. I will get that sorted 1st then get the pinion angle sorted before I worry about clearance for the driveshaft cone. One step at a time....

Keith,

Have you tried the suggestion of taking a BFH to the underside of the trans tunnel? Everyone has either done that or cut out a section like Simon Austin demonstrates in his build. The BFH took me all of 20 min without the trans in place. Without doing this I think you will have clearance issue in the tunnel and at the rear loop.

Mike, I tried but I cant get in there without pulling the motor out again. I am all by myself on this project and it took me a day to get the motor in there. Plus it seemed somewhat dangerous to do it once so I don't want to push my luck. I see that as a very last resort.

I did look at what Simon did. That might be my best bet since I can do that without pulling the motor. Less work to cut and weld and less dicey for me working alone.



Edited 1 time(s). Last edit at 07/21/2014 11:04AM by Brownwood.

Hey Kieth,

the attitude of the car doesn't make any difference to the driveshaft alignment.
What is critical is the relationship of the trans output to the diffy pinion.
Ideally both angles should match. Meaning that if you draw a line straight through the trans and another straight through the pinion.
Those lines would be perfectly parallel in both planes. Reality often precludes that ideal alignment though so a degree or so difference won't cause any big issues.
Another important angle is the drive shaft angle. Measured from the trans to the pinion you don't want a perfectly straight line. The U joints need some angle to them. Otherwise they will wear quickly and cause all sorts of harmonics.
A vertical slope when the diffy is at ride height is most common, but a horizontal offset is acceptable as well.

Hope thats helpful.
Cheers
Fred

Yes that helps. I was going for a perfectly straight driveshaft but I see the idea is to have the angles match, trans down diff up at the same angle but have them on a slightly different plane so the driveshaft isn't perfectly straight between the two.

Keith, a perfectly straight drive shaft means the needle bearings won't rotate in the cups and you're probably looking at early u-joint failure.

Paul