8.8 Gear whine reduction - BITOG thread

[MountainMichael]

8.8 Gear whine reduction - various bandaids; then permanent fix

later edit:

Thread synopsis to save some people some time:

I found various ways to reduce my 8.8's gear whine by about 75%. Much later in the thread you'll see that I subsequently did gear pattern and pinion bearing pre-load diagnostics. I then learned the axle setup was fubar and went ahead and rebuilt it 'cause at that point, there was no question it was just going to continue to get worse.

So the bandaids bought some time, but it was going to keep getting louder and louder due to very poor setup 3.55 gears OEM by Ford.

Back to the original text including some flawed assertions on my part. I've subsequently corrected any mistakes I caught.

Like most of my threads, I've included a lot of detail not knowing the experience level of the people who will read it. If you're not looking for detailed info or if you will be unduly irritated by a long read, suggest you click out now.

There is possibly some good build info in this thread such as the various things I stumbled on. Notably, at least for my specific new set of FRPP 3.73 gears, the FRPP gear pattern chart is ASS BACKWARD for pinion shim adjustment. That wasted a TON of my time.

I admit to forgetting a lot since being away from the trade for some time now.

Micke

Degreed/Cert'd ASE Master Tech (etc) - Retired for 9 years now



Original text, beginning with some things done to attenuate noise before rebuild:

Because this happens so often with OEM stock AND re-geared differentials and because my car had some minor whine that was making me a little crazy, I started a thread over in BITOG.

I'm linking it here because some oil and non oil steps have already yielded improvement; like about 75% reduction overall.

There are various threads here and there in Tech on gear whine, but the loop usually isn't closed. I'm going to follow this topic to the bitter end. Yet I don't think it deserves to be in Tech per se.

The BITOG thread is getting a lot of views and some good input.

fwiw,

Micke

aka 10bears

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2646159#Post2646159

 

[kevinatfms]

im gonna be the bearer of old bad news, if the pinion/ring gear depth and backlash are set correctly, it will not whine. i read the thread posted above and would love to know why you think it would be setup correctly, yet it still whines? have you verified exact pinion preload and pinion depth? was the pinion/ring gear marked with depth change marks?
ive corrected a quite a few 8.8's(100's easily) and even a few members on this forum. once the wear pattern starts it is very hard to get rid of, even if you reset the pinion depth and preload.
i would suggest stick with 75w-140 synthetic with friction modifier if your on the trac-lok.

 

[CPRsm]

Kevin is 100% right. Properly setup gears do not whine. It's hard to find someone to do it right, shops included.

 

[BAKnBLK2010]

This is my 3rd new Mustang starting with the 2010 and now the 2012. All three have had gear whine after installing LCA's with poly bushings. All three with the factory gears. So I guess according to Kevin they were not set up right from the factory.....

 

[CPRsm]

That's entirely possible. Although there is a difference between hearing more noise from the rear end with new bushing, and the rear end actually howling.
A while back a SVT member swore all three of his gears were done correctly but they still made noise. So it MUST be normal. Until he found his axle tube was bent.

 

[MountainMichael]

This is my 3rd new Mustang starting with the 2010 and now the 2012. All three have had gear whine after installing LCA's with poly bushings. All three with the factory gears. So I guess according to Kevin they were not set up right from the factory.....

Precisely what happened with mine. I'm gonna be the bearer of GOOD news ;-) My ultra typical 8.8 gear whine (after lca's with poly) is so minor now, most people won't hear it.

What I've done so far has gotten rid of 75% of what little was there.

I plan to check backlash and mark the gears for pattern. Seemed a little loose last time I had the cover off, but I didn't check it then. If I find problems, might rebuild it with maybe a bit more gear like maybe FRPP's NEW 3.73's (not the old N suffix 3.73 whiners)

Micke

 

[Shaffe]

Kevin is 100% right. Properly setup gears do not whine. It's to fi d someone to do it right, shops included.

This^ everytime it comes up I say this.

If its done right, it wont whine. I dont care what brand gears it is. Everyone says motive gears whine, guess what I had motive 4.10s in my 04GT and they were as quiet as my factory 3.27s They were set up correctly buy a guy who pretty all he does know is ford 8.8 rear ends. and he takes his work very seriously. He is a one man shop and he knows only way people come to him is by word of mouth.

If its done correctly it won't whine

 

[Corpo]

I totally got lucky with my 4.10's. All I did was swap the ring and pinion, I checked backlash and the wear pattern, it was good. Bolted it up using the same shims and bearings. Now, no whine, even with a bunch of rod end suspension. No whine. Sooooo lucky...

 

[MountainMichael]

That's entirely possible. Although there is a difference between hearing more noise from the rear end with new bushing, and the rear end actually howling.
A while back a SVT member swore all three of his gears were done correctly but they still made noise. So it MUST be normal. Until he found his axle tube was bent.

Yeah, no howling here ever. Just minor whine and most evident after UMI lca's and relo brackets. Checking backlash and gear pattern tomorrow.

OEM 3.55's in my car with 25,000 miles on the car and gears.

Drove 160 miles today to get tools and parts as I live way out in the sticks. Nice ride; the things I've done so far have reduced the perceptible whine by about 75% so what remains is considerably quieter than typical road noises like road roar, tire noise, wind noise, etc.

Just drained the gear oil hot after today's driving and I'm letting it drizzle and drip overnight.

Spillage on garage floor revealed that the Amsoil 75w140 is scary slippery stuff!

This^ everytime it comes up I say this.

If its done right, it wont whine. I dont care what brand gears it is. Everyone says motive gears whine, guess what I had motive 4.10s in my 04GT and they were as quiet as my factory 3.27s They were set up correctly buy a guy who pretty all he does know is ford 8.8 rear ends. and he takes his work very seriously. He is a one man shop and he knows only way people come to him is by word of mouth.

If its done correctly it won't whine

I don't disagree. Hundreds or maybe thousands of threads out there about 8.8's with gear whine - OEM low milers like my car (25,000 miles), others with aftermarket gears - sometimes redone 3 times with new bearings and gears - by 3 different shops ~ and still whine.

This is partially why whatever I do is going to be DIY. There was an excellent gear installer in Colo Spgs, and I knew I could trust him. But he is dead now - and I no longer live near there.

The last 3 jobs I've reluctantly hired out on the car cost me over $100/hr and each was impossibly badly botched. Word of mouth referrals insist the last time they were there, they received decent work on their cars. Go figure. I guess at a measily 100 per hour, the shops aren't willing to pay over minimum wage and so, can't hire anyone with any training.

While I don't have a pinion depth measuring kit any more, I've decided that if I have to pull the pinion gear, I will probably just do new gears and set it up myself. Might even go for the money hemorrhage and throw in an eaton posi while I'm at it. There will be some extra leg work due to where I live, not having a press, etc. Might have to use up a few crush sleeves and pinion nuts, But WTF. There is no excuse for the crap work that's being done in my area.

With my background, I will get it right. And I won't have to arrive at a shop to see them doing donuts in my car again!

Hate to talk bad about mechanics 'cause I'm a retired one, but man, it's hard to find anyone who will do even a passable job. Last 3, I wouldn't let them within a mile of working on my car again.

I had that guy in Colo Spgs put some pretty steep gears and a posi in a supercharged fox body years ago.

I never heard a noise out of that 8.8; not after hundreds of races. 'Course there was a T-Rex fuel pump back in that area of the car screaming away so that might have masked it now that I think about it..

I totally got lucky with my 4.10's. All I did was swap the ring and pinion, I checked backlash and the wear pattern, it was good. Bolted it up using the same shims and bearings. Now, no whine, even with a bunch of rod end suspension. No whine. Sooooo lucky...

+1, you are one of the lucky few. And with rod end suspension, you must have gotten it exceptionally quiet. Congrats!

Many who have had someone else set up their gears and are temporarily fortunate enough to have silence right now... won't in about 10k or 20,000 miles. Happens way too often. Crazy often. The net is flooded with 8.8 whine complaints, stories of woe and repeated money upchucks without getting relief.

One hypothesis might be that most axle shop mechanics are so poorly paid, they are no longer willing to take the time to get ANYTHING spot on right. Or maybe, could it be that most axle shops simply are not willing to pay wages necessary to hire and KEEP any truly qualified professional tech?

 

[weather man]

I think we all have the problem of finding a quality shop to work on our stangs. Even though the shop doing my build has a good rep. I pray every day it all turns out. Since we are talking rear ends, do the Ford Racing covers help any? I admit I bought mine 70% look and 30% function.

 

[MountainMichael]

Hey, weatherman. How ya' been?

I'm curious to hear answers on this. That big chunk of aluminum seems to me like it should damp out some vibes; especially with those studs going into the caps.

Did you feel like it reduced axle noise or have your driven with it yet? Or does your 'stang even have the dreaded whine?

Thanks for input! Looking forward to reading answers to your question.

Best of luck with the work you're getting done.

Micke

 

[weather man]

Hey, weatherman. How ya' been?

I'm curious to hear answers on this. That big chunk of aluminum seems to me like it should damp out some vibes; especially with those studs going into the caps.

Did you feel like it reduced axle noise or have your driven with it yet? Or does your 'stang even have the dreaded whine?

Thanks for input! Looking forward to reading answers to your question.

Best of luck with the work you're getting done.

Micke

Micke, It will be a little while yet before I can tell you

 

[MountainMichael]

Kevin, I'll link you over here from your thread. Been trashin' up your thread with a bunch of this stuff and no call for it. Scroll down to the next post for gear marking compound patterns. Nothing found outlined in this post that I would call diagnostically relevant. Just showing how I rigged for a couple of tests - and 1 finding: .0005" to .00075" (half to three quarters of a thousandth) side motion in the pinion gear; not enough to be causing problems YET... I don't think. But it does show the pinion bearing set no longer has preload. Could zero preload make those bearings sing? I dunno.

Backlash checked in 4 places ranged from .0115" to .013", so not terrible gear tooth or radial runout variance.

Details for this post:

First, I started with some atypical use of the dial indicator to see if there was any side slop in the timken/tapered bearings on the pinion gear or on the side bearings. I found the aforementioned miniscule side lash in the pinion flange using this dial indicator setup rig. The indicator rig was carefully isolated from anything else so I did NOT get false readings. I used hand force only up and down on the driveshaft to move the pinion flange for the test. BTW, I next turned the pinion flange and found .004" runout in it; probably not a big deal.

Image cropped to take out some blinding back lighting:

Next atypical test; I set the dial up on the back of the diff carrier - but NOT for runout; instead, once again, I was going to thrust the gear/carrier sideways to see if there was any slack in the side bearings. There was none. Zero. Here was the setup. It's a tight setup in there but could be done with a magnetic base versus the vise-grips/articulated cam setup used in the above photo:

Next up, here was the rig I used for checking backlash in 4 places on the ring gear. As noted in the preface, they ranged from .0115 to .013". That is, eleven and a half thousandths to thirteen thousandths. So the usual "butter zone" backlash of 10 to 12 is exceeded a bit:

Next up, I measured the axle to spyder cross-shaft air gap. Left was .024", right was .023". Kinda' loose but still easily within Ford spec. I'll obviously tighten that up a bit when I do the new clutch/shim stack out:

pic doesn't seem to want to load... will try again in next post..

Micke

Trying those pics again; will see if they fail again. Maybe I've exceeded my bandwidth limit?? Nope, it worked. .024" left - .023" right. M

As I'd mentioned before, I've forgotten a lot as I retired in 2-2004. Was once allegedly a passable mechanic.

I probably used too much gear marking compound. Mea culpa; it is the first time I've used the GM stuff. So the following pics show silver sharpie labeling by each of the drive and coast pics; positions 1, 2, 3 and 4 around the ring gear.

The final pair of pics is of an unlabeled in between space as that area was NOT so grossly over-doped by me with the marking compound:

Position one; drive side:

^^The above looks not horrible to me, but a bit close to the root. Then again, I have been warned against reading much into the drive pattern on used gears..


Next, Position 1 Coast Side. This looks wide to me but also a bit too close to the heel:

Next up, position 2 drive side:

Position 2 coast side. Pardon some remnants on these patterns; those occurred when rotating the ring gear under no load to photograph:

Position 3 drive side:

Position 3 Coast Side:

Position 4 Drive Side:

Position 4 Coast Side - again, odd remnants are probably from too much compound and final turn for pics not under any load:

As promised (I hope), here is an in between area that was NOT so grossly over-doped with gear marking compound by me. This one is therefore not numbered. Drive side:

Non numbered in between area coast side:

Ok, that is it for the gear pattern pics for now. Going over to link Kevin to this now.

M

Linked kevinatfms to this thread for the pattern pics; his continuing help is MUCH appreciated!

Going out to load the axle and take pinion and both driveshaft segments angles.

M

 

[kevinatfms]

This is my 3rd new Mustang starting with the 2010 and now the 2012. All three have had gear whine after installing LCA's with poly bushings. All three with the factory gears. So I guess according to Kevin they were not set up right from the factory.....

coming from me, trust me. i spent some time around the factory workers and machines, they can be off by quite a bit, hence the reason tooling is changed out every so often to identify part issues and problems. remember there was a TSB for rear ends when the 05's first came out, ended up being the gearset and fords solution was to throw axle harmonic weights onto them. well that didnt work very well and alot of rears were fully rebuilt or replaced with updated part numbers.

just because its factory doesnt mean it isnt fucked. that is what TSB's are for.

 

[MountainMichael]

Just 2 short days, and my parts are here!

Thanks, Steve! Great job once again.

If memory serves, Roush shows pics of measuring the pinion angle using the flat on the diff housing.

Problem is, I get WAY different readings between using the housing or using the pinion flange. Opinions?

Here is what I found:

With rear axle loaded... jounce the car a few times... all 3 elements (pinion snout, rear driveshaft and front driveshaft) are angled up.

That is, starting at the back of the car, all 3 angle UP from there as follows:

Pinion if measured from axle housing/casting: 6 degrees UP.

Pinion if measured from pinion flange: 3 degrees up.

Back driveshaft: Angles up from back to front 5.5 degrees

Front driveshaft: Angles up from back to front 5 degrees

Roush says they want the pinion up angle to be 2 to 4 degrees LESS than the front driveshaft. Why the front? Makes no sense to me. Would make more sense to me if comparing pinion angle to REAR driveshaft. But wtf. Either will be ok... but ONLY if the pinion flange is the better measurement.

SO: If I trust the pinion flange measurement, I'm right where I need to be. If I trust the measurement from housing casting, the pinion snout needs dropped 3 degrees or more.

However, I've read that with CV joints as my car still has, these measurements are NON critical. Whereas with U joints, it would be critical and might cause noise/wear problems.

However, my understanding is that pinion angle almost never causes whine...

Opinions appreciated..

Pics:

Here is the angle finder on the housing casting reading 6 degrees UP; there is some parallax in the pic so it might not look like 6:

Here is the angle finder on the pinion flange indicating 3 degrees UP:

This is ONLY sitting on the magnet perch; it is NOT sitting on the plastic housing. Could that be the rub or is the cast iron axle housing just not an accurate place to measure from?


Opinions appreciated; especially if you have 2 piece driveshaft and have adjusted pinion angle removing gear whine. I'm doubting that has happened but wanted to ask... input appreciated!

'k, back to Friday night drinking..

Micke

 

[kevinatfms]

ok after looking at all the pics i will comment on how the rear seems to be setup incorrectly.

on your drive side of your ring gear, you were initially correct as the pattern is much too deep indicating pinion depth issues.

on your coast side i see the wear pattern too far out from the center of the face indicating that the backlash could be tightened a little better. take it from .013 down to under .010 and you should be golden. i like to run mine loose but if you are already experiencing whine i would guess the pattern is worn into the face too much to recover it.

as far as the air gap, that seems to be well within specs, almost a little too loose. once you shim with the new packs it should be much less total air gap than before. IIRC mine was originall .060 total while the FRPP packs are .045 and with shims you can get down to under .030 if you have a BFH big enough to get the s-spring into the carrier with the ring gear on.

ill look at them again in a little and write more, im headed out to the bar for some drinks with some friends soon. once i get back ill write some more down about why i think you have gear whine, but ill start with saying the pattern does not look correct, much to deep.

 

[MountainMichael]

Here is another thought: I lowered the back of the car 1 inch. This made the rear driveshaft almost at the same angle as the front driveshaft. Shouldn't be a problem with a CV joint in between... UNLESS having it in almost a straight line is transmitting too much noise from the diff... just a thought..

 

[kevinatfms]

If memory serves, Roush shows pics of measuring the pinion angle using the flat on the diff housing.

Problem is, I get WAY different readings between using the housing or using the pinion flange. Opinions?

Here is what I found:

With rear axle loaded... jounce the car a few times... all 3 elements (pinion snout, rear driveshaft and front driveshaft) are angled up.

That is, starting at the back of the car, all 3 angle UP from there as follows:

Pinion if measured from axle housing/casting: 6 degrees UP.

Pinion if measured from pinion flange: 3 degrees up.

Back driveshaft: Angles up from back to front 5.5 degrees

Front driveshaft: Angles up from back to front 5 degrees

Roush says they want the pinion up angle to be 2 to 4 degrees LESS than the front driveshaft. Why the front? Makes no sense to me. Would make more sense to me if comparing pinion angle to REAR driveshaft. But wtf. Either will be ok... but ONLY if the pinion flange is the better measurement.

SO: If I trust the pinion flange measurement, I'm right where I need to be. If I trust the measurement from housing casting, the pinion snout needs dropped 3 degrees or more.

However, I've read that with CV joints as my car still has, these measurements are NON critical. Whereas with U joints, it would be critical and might cause noise/wear problems.

However, my understanding is that pinion angle almost never causes whine...

Opinions appreciated..

Pics:

Here is the angle finder on the housing casting reading 6 degrees UP; there is some parallax in the pic so it might not look like 6:

Here is the angle finder on the pinion flange indicating 3 degrees UP:

This is ONLY sitting on the magnet perch; it is NOT sitting on the plastic housing. Could that be the rub or is the cast iron axle housing just not an accurate place to measure from?


Opinions appreciated; especially if you have 2 piece driveshaft and have adjusted pinion angle removing gear whine. I'm doubting that has happened but wanted to ask... input appreciated!

'k, back to Friday night drinking..

Micke

before i head out, the 3 degrees is correct. you measure from the bottom portion of the pinion. that isnt too extreme but i think factory spec is -2 and acceptable up to -2.5 degrees. ill check my WSM again but im about 90% sure. the additional angle could be a factor in your pinion bearing play as it may have started to accumulate flat spotting on the face of the bearing race.

 

[kevinatfms]

Here is another thought: I lowered the back of the car 1 inch. This made the rear driveshaft almost at the same angle as the front driveshaft. Shouldn't be a problem with a CV joint in between... UNLESS having it in almost a straight line is transmitting too much noise from the diff... just a thought..

you may want to correct pinion angle with an adjustable upper control arm and or mount. i dont know if the 1 degree would really make a difference but it could be contributing to the pinion bearing wear.

 

[MountainMichael]

Kevin, much appreciated!

Tippin' a few myself.

Depending on formula, I guess I would offset my shims about .004" thicker on Dr side and .004" thinner on pass side to get backlash under .010". That appeals anyway since I have a lot of driveline clunks and clacks when shifting lower gears at light throttle. Not that it will help a lot, but ya' know.

If the carrier comes out sloppy loose, I'll adjust the above for some added preload.

However, let me know if you think I need to change pinion depth. I'm thinkin' on it myself; looking at various charts ~ that don't always agree with one another!

Will wait 'til ya' get to look at it some more before ordering shims.

At this point, my thought was to reduce backlash as you stated and then re-establish the totally missing pinion bearing preload - a bit of a PITA in the car, but whatever.

Just guessing here, but maybe pinion bearing preload helps damp some of the noise? I know it has other critical purposes; looking at a possible ancillary purpose to it.

Again, your help much appreciated!

Micke