Drivetrain Rear Gear Noise

[RangerJoe]

I did my first full gear install about three weeks ago. I driven the car three or four times and put about 30 miles on it, just to "break it in". I seemed to have a difficult time setting pinion depth using the Ratech tool, but I believe this is on me, not the tool. I also seemed to have a difficult time measuring pinion preload due to me using a click style torque wrench. That being put out there, here is my problem:

Gears sound fine as long as the drivetrain has a slight load on it. Gears do not clunk or click when initial load is applied. The only sound I get is when I am coasting. I get something between a howl and a growl, not really sure how to describe it. The sound goes away if I turn to the right, but not to the left.

I read that decel howling or growling is due to bad preload on input bearing, but the fact that it goes away with right hand turns makes me think this is not right. I am leaning towards a differential bearing, but not really sure. I have had a bad axle bearing before, but it growled during turns, not went away. Backlash was set to .010".

Someone point me in the right direction, please! I have a trusted mechanic who will redo the install for $150, but I hate being defeated by something.

Thanks in advance!

Joe

 

[CarMichael Angelo]

what brand is the gear?

 

[RangerJoe]

Frpp. But, after talking to my mechanic friend, i found out that motive now makes the frpp gearsets. However, with the characteristics of this sound, i think something is wrong.

Ratio411, got any input here? Anyone else? What is on your mind mike? I know you are pondering something.

Joe

 

[f8tlfiveo]

I'd love to help, but I do not know much in this area

 

[RangerJoe]

Well, that makes two of us!

Joe

 

[ratio411]

The only thing I am trying to grasp is how you set preload with a click wrench?
I didn't even know you could get an inch/pound wrench that clicks.
I thought they were all dial type.

I am only guessing here, but quiet on turns sounds like something else.
Maybe a carrier bearing?

I have only set up 4 rears from scratch, so I am far from 'expert' at it.

 

[ratio411]

Did you rebuild the diff too?
Just brainstorming...
The diff is what operates when you turn (duh!), so that comes to mind.

 

[ratio411]

I googled the words "diagnosing differential gear noise", and got a bunch of stuff.
I haven't read much yet, but one thing that sticks out on many sounds/diagnosis is they are for gears that already broke in and were 'previously quiet'. You are not there yet.

The diagnosis that are for gears making noise right after setup simply say "defective parts/improper setup".
Doesn't help much, but there are certain clues to be had I am sure.
http://reviews.ebay.com/Diagnosing-Differential-and-Driveline-Noises?ugid=10000000009118033
http://www.rsgear.com/articles/1996_08.pdf

 

[ratio411]

http://www.billhughes.com/temp/tracLoc.pdf

Pinion gear bearings have a constant-pitch noise.

This noise changes only with vehicle speed. Pinion

bearing noise will be higher because it rotates at a

faster rate . Drive the vehicle and load the differential.

If bearing noise occurs the pinion rear bearing is

the source of the noise. If the bearing noise is heard

during a coast, front bearing is the source.

Worn, damaged differential bearings usually produce

a low pitch noise. Differential bearing noise is

similar to pinion bearing. The pitch of differential

bearing noise is also constant and varies only with

vehicle speed.

Axle shaft bearings produce noise and vibration

when worn or damaged. The noise generally changes

when the bearings are loaded. Road test the vehicle .

Turn the vehicle sharply to the left and to the right.

This will load the bearings and change the noise

level. Where axle bearing damage is slight, the noise

is usually not noticeable at speeds above 30 mph.

It says bearing noise on coast points to the front bearing.
That points to preload IMO.

Something else I read elsewhere: "whine = too loose/growl (rumble) = too tight"
Take that with a grain of salt though! I just thought it was interesting.

 

[7991LXnSHO]

I am afraid this sounds right. The pickiness of the set up is why I do not do rear end work by myself. BUT also check the U joints too as they can do wierd things.

 

[clement]

Frpp. But, after talking to my mechanic friend, i found out that motive now makes the frpp gearsets. However, with the characteristics of this sound, i think something is wrong.


Joe

if you look at the newer FRPP gears from around the last 5 years vs. older gears, the angle of the tooth face is different as well as the newer ones being chinese. the newer gears all seem to have a coast howl. if you buy factory ford gears for like a gt500 they are like the 'old' FMS gears and dont make noise. as long as the setup is correct, they are probably fine. they are just going to be loud. the gears are different than they used to be. i have about a 15 year old set of gears in mine right now that were used when i set them up and dont make hardly any noise. i have set up new frpp and motive gears that i couldnt get to shut up on coast and the pattern was great.

 

[RangerJoe]

I googled the words "diagnosing differential gear noise", and got a bunch of stuff.
I haven't read much yet, but one thing that sticks out on many sounds/diagnosis is they are for gears that already broke in and were 'previously quiet'. You are not there yet.

The diagnosis that are for gears making noise right after setup simply say "defective parts/improper setup".
Doesn't help much, but there are certain clues to be had I am sure.
http://reviews.ebay.com/Diagnosing-Differential-and-Driveline-Noises?ugid=10000000009118033
http://www.rsgear.com/articles/1996_08.pdf

Hey Ratio,

Yeah I have read about everything I could find on the net about this. Yes, my inch pound wrench is a click style. I borrowed it from my father-n-law as well as the Ratech tool (I think it is an older Craftsman). Although, he uses the solid spacer instead of the crush sleeve. I don't know if this makes a difference, but he said it is much easier to set up. I am sure it is a bearing, just not sure which one it is. I was leaning towards the pinion bearing, but after noticing that it goes away on right hand turns, it made me think it could be a carrier bearing. I may try adding a 1/4 turn to the pinion nut and see what happens. I will only drive it a short distance, if no immediate improvement, then I will probably let the mechanic have a stab at it.

if you look at the newer FRPP gears from around the last 5 years vs. older gears, the angle of the tooth face is different as well as the newer ones being chinese. the newer gears all seem to have a coast howl. if you buy factory ford gears for like a gt500 they are like the 'old' FMS gears and dont make noise. as long as the setup is correct, they are probably fine. they are just going to be loud. the gears are different than they used to be. i have about a 15 year old set of gears in mine right now that were used when i set them up and dont make hardly any noise. i have set up new frpp and motive gears that i couldnt get to shut up on coast and the pattern was great.

This is basically the same advice the mechanic gave me. I just can't stand to think something could be wrong with it. On second thought, I may just take it on over there and let him listen to it before I touch anything.

Thanks again guys!

Joe


Joe

 

[7991LXnSHO]

So what do you buy for good, quiet gears now besides GT500 ones???

 

[RangerJoe]

So what do you buy for good, quiet gears now besides GT500 ones???

I don't know. When I talked to him about it, he seemed very disgusted. He claimed to have installed around 2000 ford made gearsets over the last twenty years. He said he never had problems out of the ford made ones. Then about two years ago, he had a set that wouldn't be quiet. He pulled the out to inspect and noticed they looked a little different. Called frpp and found out they were no longer making their own.

I passed on a new in box pro 5.0 gear for real cheap because i wanted an easy to install frpp. Maybe i should have gotten them. Either way, i really don't think this noise is caused by the gears alone.

Joe

 

[clement]

So what do you buy for good, quiet gears now besides GT500 ones???

i dont know. i have all the old 8.8 gears i could ever need for that reason. its a big pain in the ass.

 

[clement]

even to get to the low side of the torque spec on the pinion is pretty difficult to get. i set mine at 12"lbs because it was a bitch to get any more crush on it. at 12" lbs my pinion is very smooth and easy to turn. as far as depth; most of the housings i have taken apart (probably between 75-80 since i did my first in '94) most of the factory pinion shims are .026". my car came with a .022". the old rule used to be if you were using a FMS gear to start with the factory pinion shim, eyeball the carrier shims and check pattern. 99% of the time the factory pinion shim was the perfect depth with a ford gear. but the pinion depth can be a little different because it depends on your individual housing in the end. if you dont know you just have to start with your best guess, shim it and run pattern to find where you need to go with it. how did your pattern look? what about the carrier and pinion bearings? it doesnt really surprise me that the pinion was a bitch to set, that is normal. pull the cover, look at the pattern again and look at the fluid. if the pattern is good and hasnt changed and the fluid doesnt have metal in it i would put it back together and leave it alone.

 

[CarMichael Angelo]

Frpp. But, after talking to my mechanic friend, i found out that motive now makes the frpp gearsets. However, with the characteristics of this sound, i think something is wrong.

Ratio411, got any input here? Anyone else? What is on your mind mike? I know you are pondering something.

Joe

Sorry to get back so late to this,..but the reason I asked is that the Motive set I had originally in my car turned out to be a set intended for 4WD off road applications. After talking w/ the Motive dude, he told me that I would never get them quiet because of the sloppier tolerances and the disregard for quite noise levels when they were finished.
He told me that a the average 200.00 motorsport set would be the solution,..and it was for me.

 

[RangerJoe]

even to get to the low side of the torque spec on the pinion is pretty difficult to get. i set mine at 12"lbs because it was a **** to get any more crush on it. at 12" lbs my pinion is very smooth and easy to turn. as far as depth; most of the housings i have taken apart (probably between 75-80 since i did my first in '94) most of the factory pinion shims are .026". my car came with a .022". the old rule used to be if you were using a FMS gear to start with the factory pinion shim, eyeball the carrier shims and check pattern. 99% of the time the factory pinion shim was the perfect depth with a ford gear. but the pinion depth can be a little different because it depends on your individual housing in the end. if you dont know you just have to start with your best guess, shim it and run pattern to find where you need to go with it. how did your pattern look? what about the carrier and pinion bearings? it doesnt really surprise me that the pinion was a **** to set, that is normal. pull the cover, look at the pattern again and look at the fluid. if the pattern is good and hasnt changed and the fluid doesnt have metal in it i would put it back together and leave it alone.

Well, been thinking on this. Do you think the force caused by turning the car would apply a load to the pinion bearing and cause it to be quiet? I used a .027 shim on the pinion btw. I'm still wondering if i don't have enough preload on my input bearing.

Joe

 

[clement]

i think its more that turning one way the gear is on the coast side and turning the other its not. the few pinion bearing issues ive seen had a vibration, not just a noise. that and the pattern changed and ruined the gears. pull the cover and see how it looks. if you want pull the axles too and turn it by hand to see how it feels that should tell you everything you need to know. in the end the pattern is what matters.

 

[RangerJoe]

Well, just to update. I carried it to my mechanic yesterday. He said i did 't have enough preload on my carrier bearings. I'm a little embarrassed to say i didn't realize you had to check this. I assumed that would take care of itsself with the backlash. Don't know, maybe i measured it incorrectly. He said i actually had my pinion depth and pinion preload right, go figure. Also said it was a good thing i didn't drive it too much.

I appreciate all the help you guys gave. Just wanted to update thread.

Joe