8 3/4 question

[david411]

Has any of you used Dr Diff's complete center section? If so, did it have any whine or was it quiet?
My existing rear end ( with only 400 miles) had noise so I had the gear set and bearings replaced and within 1500 miles it also developed noise (whine). The work was done by different shops. The second shop has the car back and has used 3 different gear sets and are not pleased with the noise. I don't know weather to spend $ 800.00 on an NOS gear set or $1400.00 on a new diff.
I just want to stop the whine.

 

[moparleo]

The type of noise needs to be properly diagnosed first. Bearings and/or gears ?

 

[david411]

Gear noise for sure.

 

[MOPARMITCH]

The main problem , is the pinion depth. Must be set correctly for the case in question. Most times, if using the same case, with new gears, the pinion shims can be re used, so the depth is set correctly. If a new case, then there is a tool to check pinion depth, so it is correct. It is ALWAYS advisable to check pinion depth. After that , It is only an adjustment of of the ring gear case, side to side, done with the adjusters, provided on the ring case, itself....

 

[david411]

All the work on the diff is being done by a shop that only does driveline work ie clutch, rearends and driveshaft building and balancing. I would think they would how to properly set up a diff. They say the problem is the after market gears. I don't know.

 

[Cudafor36]

My new 489 pig and 3:55's whine as well. Running green bearings. Bought it from Drive line works in FL (Joe). Called him and he said the new gear sets whine a little unlike oem. Argh.

 

[aussiemark]

Maybe find some good used OEM gears.

 

[david411]

Mine was more than a little whine. At about 40 MPH under LIGHT acceleration it sounded like the law was behind me. LOL It was not nearly as noisy at deceleration.

 

[john-9]

after 3 or 4 gear sets ,,spending $800.00 on a NOS gear set is not going to solve the problem -- the shop/shops being used obviously have no clue of what they are doing -- the gear set is not the problem ,, the mistake the shops are making is on setting the pinion depth and pinion bearing preload correctly as well as not specifying a break in for the new gears and bearings - time is money to them and they do not want to spend any more time than is necessary ,,so close is good enough ,, then they blame the gear sets and you are sol.
ask around there are people/shops that do take pride in their work -- a gear set up properly will make no noise ---

 

[MOPARMITCH]

after 3 or 4 gear sets ,,spending $800.00 on a NOS gear set is not going to solve the problem -- the shop/shops being used obviously have no clue of what they are doing -- the gear set is not the problem ,, the mistake the shops are making is on setting the pinion depth and pinion bearing preload correctly as well as not specifying a break in for the new gears and bearings - time is money to them and they do not want to spend any more time than is necessary ,,so close is good enough ,, then they blame the gear sets and you are sol.
ask around there are people/shops that do take pride in their work -- a gear set up properly will make no noise ---

Agreed...See post #4......

 

[david411]

I have not bought the NOS $800. gear set yet. It was an option if all aftermarket gear sets have a whine.

 

[john-9]

the shop did the gear set up - did you do the install of the rebuilt center section into your car or did the shop do that as well -- if you did the install -- did you notice if the shop did a pattern check with gear marking compound to make sure the gears were meshing properly . if not then for sure the gears were not set up correctly.
the pattern check is the final say on the correct gear set up -- once the correct pattern is achieved , now you do the final assembly which will be pinion bearing preload and backlash . this goes for all differentials Ford , Gm , Chrysler etc.
here are a couple pics of 8-3/4 I've done showing the patterns

if all after market gears were noisy --no one would buy them

 

[david411]

They did the install so I did not see the pattern.

 

[aussiemark]

 

[david411]

Thanks

 

[Scorch]

I had mine done by Quick Performance and had no problems. I installed it myself and beat the snot out of it with my Crate Hemi for the last 10,000 miles. Still going strong. Check them out at https://www.quickperformance.com.