Hi all,

The rear-end on my 67 is stock so I am assuming that it is a 8". Earlier this year I switched from 2.79 to 3.55 (perfect fit for my T5 and my cam) and unfortunately ever since (or so) there is an annoying noise from the rear-end.

It basically only happens when I am accelerating. I hear it the most when I am cruising at low speed (the exhaust is not too loud then) and just a super slight pressure on the right pedal and I can hear noise from the rear-end. It sounds like when you are going in reverse gear with any kind of car (not really nice).

What should be my plan of action here? Fluid? New bearings? Complete replacement?

Thanks a lot!

 

You have a low low piched whine correct? It sounds like who ever installed your new gears did not set the lash correctly. It is not a worn out issue. however the gears will wear prematurely. You need to take it back to whoever installed them and have them redo it.
If you did it then you need to buy a new differential kit and set the lash. you can find exactly how to do this via google. It is not difficult but you must be precise.

 

ya. it might be the lash between pinion and gear. especially if it's since you changed.
If it only came in now it could mean damage like pinion bearing etc. but if the pinion and ring were new and all bearings replaced during install I'd say the lash wasn't set correctly

 

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Your rearend is likely an 8" unless it is a big block car. The easiest way to tell at a glance is to look at the bottom two nuts holding the center section in the housing. If you can use a socket and ratchet on them, it is an 8". If the pinioin support overhangs the nuts so you would have to use a wrench to get them off it is a 9".

Were the gears new or used when you put them in? It is almost impossible to get a correct pattern on used gears when you swap them to a different carrier and bearings. The result will be some gear whine. If the gears were new, then it probably wasn't patterned correctly.