3.55:1 rear end noise, is it normal?
 

I have one question. I had my 8 rear-end upgrades with a 3.55:1 possi trac. for my 65 Mustang. It was a complete overhaul, all bearings and seals were allegedly replaced with new ones. I spent a little bit over 1000 dollars for this upgrade. The brand of the ring and pinion and possitrack is Auburn brand.
However, I was pretty dissapointed because this rear end rears make noise opon acceleration. Most noticable after about 35-40 MPH and above . The noise disappears open disangagement of acceleration. I returned to the mechanic Performance Differentail in city of Ontario California, and he stated that such noise was normal especially on 3:55:1 gears. Is this normal?
I can't really stand this noise. It is embarassing because my passengers always ask me "what is that noise" "what's wrong with your car" "are you sure we won't get stranded?",. And I paid exactaly $ 1057.93 According to him it is normal. I would like to know if any of you guys that have upgraded your rear end with same appication have the same problem as I do? What can I do to eliminate this noise. I am know considering on going back to my 2:70:1 non possitrac, to get rid of this embarassing noise.

The only thing I can add is that I have been warned about ring and pinions that are not Ford brand can cause some noise. Have you taken the guy for a ride and let him hear the noise?

Yes, I have taken the car back to him and he test drove it. He stated the noise is normal on all 3.55s. The noise get real annoying on highway speeds. Can't stand it, I am about to swap a used differential.

there better not be a normal noise associated with 3.55's i just bought some and there in the mail!!!

the reason im putting them in was because my orignal 2.80 were making a lot of noise.

anyway what kind of noise is it making. you need special oil for posi gears.. maybe he didnt put the right kind in..

is it a chattering or a whine sound or what??

Currie
 

When I ordered my 3.25 Traction-Lock center section several years ago from Currie in Ca., I specifically asked if there would be any gear noise. They said if there was to send it back at their expense. There wasn't any at all.

Rev

The noise it makes it's similar to the noise of a bad wheel bearing going bad, with the exception that upon disangaging throttle, the noise goes away.
I would like to here more from other guys who have 3.55 possi done. If this noise is not normal, what should I do to take care of it. The differential guy said he added a special kind of additive, but I am not sure if it is to get rid of the noise. Obviously not because the noise is not done.

My experience is pretty much the same as Rev's. I went the Currie route with 3.25s. After install, there was a whinning noise around 40 mph. I sent the 3rd member back to them and they replaced the ring and pinion gears. Now no whine.

In talking to local Mustang owners at car shows, this is a pretty common problem with the 8" rear end. Most have solved the problem by going to a 9" rear end.

well i just bought 3.55's in a already built third member so im hoping theres no noise. Should be here tuesday. im hoping nothings wrong with them. If they are messed up that guys going to hear from me. He said there set and ready to be put in.

The noise you describe is in the ring and pinion. It is only on acceleration and goes away on coast.

Either the ring set is bad, too much runnout, or it is set wrong on the power side.

Isn't normal and shouldn't do it. It won't hurt anything, just drive you and passengers crazy. It "won't" go away with time.

well i just got my rear from currie 355 and i have no weird sound coming from it sound like something is going wrong in there make sure he put in the the special fluid , i was also talking to my dad about this and he said it sounds like it is a ring and pinon problem

Thanks guys for the response. So do you guys think this problem should be responsibility of the person who installed this, or is this something that I should bite the bullet and deal with. What do you guys recommend? What should I do. Am I responsible for paying, to do what I need to do to eliminate this noise?

i think you should go back and he should fix it i he does not want to fix it forget him

It's either he installed it wrong or the ring and pinion are bad. Either way he is responsible.

I agree with the above opinions. Give the guy a chance to rectify the problem. If he won't, then (tell him your intentions) and make a complaint to the Better Business Burough (or the eqivalent) and then post it on the internet at various sites.

Then find a competent outfit to fix it (could even be just a lash adjustment).

Rev

Limited slip and locking rear ends are known to produce noise. They become a lot more noisy when the correct additives are not introduced into the lube oil. My Corvette used to like to "growl" going around corners when the lubricant wasn't in correct proportions. GM used to give me a shot of their "whale oil" additive to stop the growling. With their positraction axle using the correct oil makes a difference. I would have yours drained and refilled at another competent shop to see if it make a difference. They may also offer you advice concerning the noise.

Friction modifier
 

That's right Jeff, but his noise is in a straight line . That should mean ring and pinion. The Friction Modifier (available from Ford) added to the gear oil keeps the Traction-Lock from clunking and chattering when cornering. It's just a small little bottle of about 6-10 oz.

Rev

Re: Friction modifier
 

Concur...or a bearing perhaps.