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Gear Whine Normal?

Just installed a new pumpkin in my s550. Already had subframe bushing and diff bushing collars. Very little gear whine before. 3.55’s on a traction loc. “New” diff is a torsen in a loaded pumpkin with 3.73’s from an auto wrecker. Had to have the pinion flanges swapped and had the local ford dealer do that so I could be sure not to screw up the pinion bearing preload.

Below freeway speeds no whine. At freeway speeds there’s very audible high pitched gear whine at light throttle. Pitch and volume reduces at higher loads. Zero noise at no load or decel.

Sound normal? I’ve read that torsens can be louder and 3.73’s can be louder than higher gear ratios but not sure if either claim is true.
 

JDee

Ancient Racer
1,300
1,179
Exp. Type
W2W Racing
Exp. Level
20+ Years
halfway between Mosport and Shannonville
Normal with my car, same rear end as you now have. But. It's had all the rubber/noise deadening taken out of the drivetrain so there's loads of gear whine, clunk from any clutch use or accel/decel and so forth. Pretty much what I would expect when all the sound deadening things are locked out or removed.
 
38
33
Exp. Type
W2W Racing
Exp. Level
Under 3 Years
Scottsdale
It is pretty normal. Mine made quite a bit of noise until I switched over to Millers Oils CRX 75w140 without additive. Now it makes very little noise.
 
Thanks guys. Guess I was lucky with my last diff with it being quiet. Just wanted to make sure (without tearing the diff apart) that it didn’t sound like incorrect backlash as a result of the pinion flange swap.

Also I specifically chose an oil without friction modifier to increase the effective TBR so maybe the lack of modifier makes it noisier too? But that sounds opposite of your experience @S550AZ
 
38
33
Exp. Type
W2W Racing
Exp. Level
Under 3 Years
Scottsdale
Yes, I had a substantial reduction switching over to the miller oil. I used factory, then tried Royal Purple and then went with the miller.
 

Dave_W

Cones - not just for ice cream
412
397
Exp. Type
Autocross
Exp. Level
20+ Years
Connecticut
I switched over to Millers Oils CRX 75w140 without additive.
Where do you buy yours at? Went looking and most outlets were in the UK. Did find it here: https://performanceracingoils.com/millers-oils-crx-75w140-nt-competition-gear-oil/ I think the description saying it includes friction modifier is wrong (I've emailed them about it). It seems the rule of thumb for Millers gear oils is if it has "LS" in the name, it's got the friction modifier, and without "LS" in the name it doesn't.
 

JDee

Ancient Racer
1,300
1,179
Exp. Type
W2W Racing
Exp. Level
20+ Years
halfway between Mosport and Shannonville
I have had pretty good luck with the BG Ultra Guard LS. With the Ford factory fill I would get axle overheats all the time but with this BG stuff that dropped to zero. I changed it out this spring and after about 15 track days it came out of there looking like new, was kicking my ass for dumping it! I wanted to try RedLine 75W140 so that's what's in there now, if it doesn't pan out I will for sure go back to the BG. I was going to put a cooler on the diff but not necessary so far. I used the BG trans fluid as well but there was no magic in it, ended up with a junked MT-82 anyway. I guess there's no helping a lost cause.....
 
3,781
3,715
Generally, the faster you spin the gears (3.23 vs 4.11) the more susceptible they are to gear whine for the obvious reasons. that being said, removing the rubber and installing urethane bushings translates that tot he chassis even more. I've seen 3.55s that were noisier than 4.11s, it just depends on the guy building the diff and any influences of the machining process in gear production. Not only that, but the 8.8 is probably the most noisy diff I have ever had my hands on even when they are perfect.
 

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