Pinion angle and gear whine

[04mustang70]

I have a 70 Mach 1. I recently bought and installed a 3.70 trac loc geared chunk . I love the acceleration difference between the 2.90 gear I had before. Theres a massive deceleration whine now though. Is there anything I can do about that? Or is it just from aftermarket gears? I believe there yukon gears.

Second question is I used 1 inch lowering blocks to lower the rearend. ( shame on me) Do I have to be concerned about altering the pinion angle? There does seem to be some vibration at or around 50 mph? Will the 1 inch make a difference in the pinion angle? How would I measure the pinion angle? I've read most articles on this and don't see any easy way of measuring the pinion angle. I would love to solve both these problems. thanks

 

[zookeeper]

Nothing at all wrong with using 1 inch blocks. They are also not going to cause gear whine. Noise on decel is typically from excessive gear lash, so I'd have it checked before you tear something up. Lots of work, but necessary.

 

[68EFIvert]

I also have the same rear end setup as you and have the same gear whine under deceleration. Did you get your unit from TJ on Ebay? I think he lives in PA IIRC.

 

[04mustang70]

So you don't think the 1 inch blocks affect the pinion angle enough to worry about it?

 

[phutch11]

The gear whine is definitely too much lash on the gears.

Check the pinion angle with a $3 inclinometer from Harbor Freight. Slap it on the bottom of the rear end housing and see what she says. Do the same on the bottom of the starter to get the angle of the engine/tranny.

You want them to be equal or as close as you can get.

Posted via Mobile Device

 

[zookeeper]

So you don't think the 1 inch blocks affect the pinion angle enough to worry about it?

Not at all. If the pinion angle is off by too much, the result will be vibration, not noise. If your car doesn't shake at freeway speeds, consider the pinion angle to be close enough to live with.

 

[Hack]

If you just bought a new center chunk and you have gear whine, you should send it back. Pinion angle has nothing to do with it. The center chunk is set up incorrectly.