How did my pinion angle get so out of whack over the years?

I get that the new engine likely went in with a couple more degrees of angle, but even before that, I have had horrible drivetrain noise and just recently figured out it is due to my pinion facing so far downward.

How did this come to be?

Even stock, it shouldn't be facing downward that much if the engine is facing downward as well.

New 4 leaf springs and stock shackle replacements are all I have done to the rear.

 

The backwards carb thread got me thinking that somewhere along the way.. that rear-end probably got installed upside down.

Seriously though.. I can't imagine it being that far off from the factory spec to cause this issue. Did the front suspension swap make things worse?

 

It has always been bad, as far as I know. around 2006 I started to complain about it. I may need to look back at what else I did to the car around then.

It got a little worse after the front swap because the engine now sits at a bit more of an angle. Not sure at what angle a stock engine sits, but after the R&C I am pretty sure it added a degree or two. I guess they raised the engine mounts an inch or so so the oil pan would clear all the steering stuff. Even then, it is VERY close up there.

That just added another couple degrees to the already existing \______/ lineup. Regardless, the rear should have never been set up to have a \_____ setup, unless everything else was at 0 degrees level and they put in 2 degrees negative to line up under load.

 

Maybe the 5.0 block sits higher than the 302 block? Seems like that is when it all started to hum. When I cratered my 302 and put in the 5.0.

 

Might just cut off the perches and reweld them on further back on the tube, rather than drive around with wedges under them. They just don't look safe.

 

How are the rear springs? have you ever replaced them?

 

Yes, I swapped them right around the time the noise started. 4 leaf, new from JCWhitney.

but I did a lot of things "right around the time the noise started. But back then I thought it was a cool sound. Sounded like the hum from a wwII bomber.

But honestly, it got really annoying around the time I put the 5.0 in, but again, lots of changes right around there.

 

My 74 had a noise in the rearend, it probably still has it, I haven't driven it for 14 years...but it had the noise from the day I bought it.

 

Rearend has been rebuilt around that time too. This doesn't sound like rearend noise, anyway. And I took it back apart and had bearings etc. inspected by a rearend place, no problems.

This is definitely u-joint angles.

 

IIRC the stock engines/trannys had the trans tail down 5* and the pinion was down 3 or 4* because it raises under load by the pinion gear riding up the ring gear. They make aluminum wedges that you can put between the springs and perches to adjust the pinion angle.
http://www.summitracing.com/parts/sum-770025/overview/

 

Well, if that is stock, that is what I started with two. I had 5 and 4, driveshaft was level at 0.

Maybe the stiffer springs prevented the lift where the stock springs would allow more?

Of course the caltracs prevented even more.

THAT would explain my predicament.

 

The 8" in my car has always made some noise. It runs smooth till about 75mph then has a vibration that seems to be unfindable (is that a word?). The noise sounds like gear noise from the 3:55, and has been there since I put it in. Wear is normal, no chips or cracks. Any ideas????

 

I was also thinking that, if there were wedges installed already, they might have been installed backwards when having the rear in and out

 

Originally no wedges, I had been running 2 degree wedges, which made a little difference. But I was unable to get good readings on the protractor until I read some hints on where to measure from. Now that I am getting good accurate readings, I realized that I needed 6 degrees of wedges. That is a LOT of wedge. If I need to move things that far, I will re-weld the perches.

 

Does the car need to be level, to check all this stuff?