4.10s in and making noise!

peepeeskillz · Dec 20, 2009

i just finished installing my 4.10s and drove about 5 miles and they are whining, mostly in 4th and 5th gear while cruising a constant speed. i installed them myself(first time) and i used new pinion bearings only, set the rotational drag at between 20-26 inch pounds, set the pinion depth so the gear thickness was the same as the stock one, and measured my backlash to be .011. did i do something wrong!? or will they quiet down after they are broken in all the way?

thx for any help

peepeeskillz · Dec 20, 2009

i made a video

YouTube - 4.10s whining

i hope this helps, its kind of hard to hear, at the end of the video its easier to hear
any help would be greatly appreciated!!!

Kilgore Trout · Dec 21, 2009

It is normal to have to go back in and reset the pinion depth and/or backlash to get it just right and whine free.

peepeeskillz · Dec 21, 2009

oh, i guess ill have to do that. Is the car ok to drive for now until i have time to do that, or should i just not drive it until it is whine free?
thx for the help!

SVT32VDOHC · Dec 21, 2009

Did you use friction modifier with your fluid? They will make noise if you didn't.

peepeeskillz · Dec 21, 2009

yes, i put in 4 ounces of friction modifier, and ~2.5 quarts of 75w90 oil

Tanus · Dec 21, 2009

did you use that putty stuff to look at the wear pattern?

peepeeskillz · Dec 21, 2009

no i didn't do that, thats the first thing im going to do when i get enough time to take it back apart.
stupid me, i guess i should have done that after the install to make sure it was correct, was thinking if everything was set up to spec i wouldn't need to do that.

thx for the help guys, should i just park it until it is fixed, or can i still drive it to see if the whine goes away after break in?

Kilgore Trout · Dec 21, 2009

I think it is ok to drive but try to do so as little as possible. I do not think driving it is a safety issue but it may cause premature wearing of the gear teeth if they are not meshing properly.

Tanus · Dec 21, 2009

doing the pattern thing is a must IMO, do it, if the pattern is good, your fine, not sure how loud it is, but a little squiking is normal during the break-in period. Ive done a bunch of gear swaps, gets easier everytime you do it.

1987stangman · Dec 21, 2009

peepeeskillz said:
i just finished installing my 4.10s and drove about 5 miles and they are whining, mostly in 4th and 5th gear while cruising a constant speed. i installed them myself(first time) and i used new pinion bearings only, set the rotational drag at between 20-26 inch pounds, set the pinion depth so the gear thickness was the same as the stock one, and measured my backlash to be .011. did i do something wrong!? or will they quiet down after they are broken in all the way?

thx for any help

What gears did you use? If you used FMS gears, here is the setup article that started it all for me.

Installing Gears

You say you set the pinion depth same as stock? If so, I'm gonna bet the pinion shim is going to be thicker than stock setup. Also, I'm sure you did, but did you install a new crush sleeve?

rockyracoon · Dec 21, 2009

new or used gears? if they are used gears it may be hard to get that whine to stop as the gears already have a wear pattern,and IMO you would have to get the gears set up exactly as they were in their previous application,also as previously asked,did you use a new crush sleeve?

peepeeskillz · Dec 21, 2009

the gears i used are FRPP 4.10s, i was following that same article 1987stangman lol. the gears were brand new and i used the crush sleeve that came with the gears.

can gear whine mess up the transmission? i was talking to this one guy at work today, and he was telling me it could mess up my trans, i think they are getting noisier but it might just be my imagination. ive driven a total of 20 miles with them now, and it whines the loudest when barely on the gas cruising, doesnt usually whine under acceleration not until 3rd gear anyways. and also if im totally off the gas coasting in a low gear like 2nd at around 2k rpms i can feel my shifter vibrating, is this normal? it never did that with my stock gears

wmburns · Dec 22, 2009

peepeeskillz said:
can gear whine mess up the transmission?

ive driven a total of 20 miles with them now, and it whines the loudest when barely on the gas cruising, doesnt usually whine under acceleration not until 3rd gear anyways. and also if im totally off the gas coasting in a low gear like 2nd at around 2k rpms i can feel my shifter vibrating, is this normal? it never did that with my stock gears

My take on some of the questions and comments so far.

Rear end gears hurting the transmission: NO.

Gear Oil. Post stated the 2.5 quarts of gear oil were used. Consider that it may be OVERFILLED. The fluid level should be 1/4-9/16-in below the fill hole. This is not fill it up until it runs out. There has to be room for expansion. The car MUST be level. This means if the rear has been jacked up, the front must be as well.

Have you considered that which gear you are in shouldn't have any effect on the sounds from the rear end? In cases where the sound changes with the gear, its more likely the problem is in the transmission.

However, see you own comment about shifter vibration. Did you index the drive shaft and companion flange when it was removed? If not installed in the same relationship to each other, this could be the source of the vibration.

Will continued driving will hurt the car. IMO the answer is most likely no. The break in period for a new rear end should be hundreds of miles. At 20 miles, you have hardly used the new gears at all. Come back in a couple of hundred (or even a thousand).

I did listen to the video. They didn't sound all that bad to me. I did hear some change in pitch in response to drive line lash. However, that could have just as easily been the transmission.

If anything was done wrong it was how you set up the pinion depth. Not a good idea to assume it was the same as the gears removed. And since a paint contact check was not done, you have nothing to cross check your work to.

So if you are super anal, do a paint check. If the whine is only minor, drive it. Either way, check the fluid level.

>>From Ford Service cd for 8.8 solid rear axle.
1.66-1.77-liters (3.5-3.75-pints) 6.4-14.3-mm (1/4-9/16-in) below the bottom of the fill hole

peepeeskillz · Dec 22, 2009

kk thx for the imput, in a couple of days i plan on doing the paint check, and recheck the backlash.
and the car was level while i filled it, but i filled it until it started running out so there might be too much oil. and i also marked the driveshaft.

thx for the help!

Stangster007 · Dec 22, 2009

IMHO absolutely do a check with gear mesh dye, it's the only way you can know where you are with the pinion depth. Even if you were installing brand-new factory gears you would have to do this. And aftermarket gears have far more variance.

Some brands of gears are stamped with the pinion depth measured from the axle centerline, which is determined by running the gears on a special machine at the factory. But even if you have this measurement, it takes special tools to put it to use. So thus the dye.

I definitely wouldn't be driving on the gearset. Improper depth means improper loading on the gear teeth, which could easily make them run hot, which could heat them up enough to lose the hardening at the contact points, which means even after you get the gears properly adjusted later they could wear out prematurely and you'll be back at square one.

My $0.02 anyway.

wmburns · Dec 22, 2009

Another way to guage risk

An alternate view to above.

If the following were true.

Racing
Very high horse power. Incomplete gear mesh could break teeth.
Were planning on running for tens of thousands of miles
abnormal noise esp metalic "chuckle" or clunk.

I whole heartly agree with Stangster007, don't drive it.

Consider that there are no metalic noises. It is reasonable to conclude that the ring/pinion set up is close (just a slight whine). So if the plan is to normally street drive it for a while and then evaluate after a short while, go for it.

rockyracoon · Dec 22, 2009

ratech makes a pinion depth setting tool for for 8.8s,it is not a lot of money,prolly like 30 bux.
I hate gear whine,it drives me nuts.but as previously stated you need to use the marking compound,and remember you should have a load/drag on the gears when you do your check.

peepeeskillz · Dec 23, 2009

oh just to clarify i didn't just install the new pinion assuming that it was same as the stock, i measured the head thickness with a caliper and used shims to make the new pinion head thickness the same as stock or thats what i thought the MHD method called for.
but when i get time im going to do the dye test to see whats up, hopefully its not my pinion depth

Tanus · Dec 23, 2009

first gear swap I did i had to swap the pinion shim like 8 times before I got it right, Im an expert at pressing bearings on/off now, haha.

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