What grease in tranny & rear end ?

[Racer57]

'70 Cuda with 383 4-speed and 3.91 SureGrip rearend. Both were rebuilt but whine. Possibly need more miles for breakend or rear not quite set perfect. Is it possible to totally eliminate whine and what lube are you using ?

 

[ramenth]

As far as the rear goes I have to ask, did you use additive for LSD's?

Have you adjusted the clutch? A throw out bearing that doesn't release all the way will whine.

 

[moparleo]

Unless you have square cut gears, no amount of whining is normal. If the whining increases pitch with vehicle speed, it is in the differential. If it goes up and down with gear shifts, its in the box. Get it inspected before you have to start buying parts. Was the work done by a professional garage, or a friend?

 

[Racer57]

Unless you have square cut gears, no amount of whining is normal. If the whining increases pitch with vehicle speed, it is in the differential. If it goes up and down with gear shifts, its in the box. Get it inspected before you have to start buying parts. Was the work done by a professional garage, or a friend?

The previous owner had them rebuilt so I don't know who did it.

 

[moparleo]

Have you checked the fluid levels ? Where do you live ? 75/90w will work for both.

 

[Racer57]

All levels are ok. I live in Illinois, but it won't be driven in the winter if that's why your asking.

 

[moparleo]

You got it. Did you narrow the noise down to gear box or dif ? If so, try to drain the oil and refill with proper fluids so you know what is in them. Also like Ramenth said, you need a friction modifier if it has a Sure grip differential. Limited Slip Differential known as LSD. Not the drug.

 

[Racer57]

I narrowed it down to the tranny. Would something like Marvel Mystery Oil or a Lucas product help with whine ? If it don't get any better with wear or oil/additives then I guess I got a winter project.

 

[moparleo]

Try the Lucas, but it is probably too late for the bearings.

 

[Racer57]

I'm pretty sure that the bearings are good since the tranny was rebuilt less than 1,000miles ago. I now suspect the backlash wasn't set correctly. Or at least I hope to hell that's whats wrong.

Thanks for the replies.

 

[moparleo]

Not if it has been making noise for 1,000 miles. No backlash on trans gears, you can't change the distance between clusters. The gears are parallel to each other unlike a pinion gear that can be adjusted for depth and is at a right angle to the ring gear.
I have no drawing skills, so use your imagination on this.

 

[Racer57]

Is there anything that could be not set properly upon rebuild in the tranny ? How about the synchronizer ?

 

[moparleo]

The synchros just allow smooth transition from one gear to the next without grinding.