Technical Acceptable 9" rear end gear pattern........opinons please.

Hi!
I know these questions have been seen here before, but we do it one more time...... ;-)

This first pic is "Drive" side with 0.008" backlash, and 0.011" shim on pinion carrier.
Second pic is "Coast" side.

Is this acceptable or not?

// best regards, Roger .

 

As long as your preloads are good...run it.It doesn't get much better than this.

 

My installation kit says 13-15 inch/pounds preload ( new Koyo bearings), but my search on internet says around 20-22 inch/pounds on new ones.............What do you think? //Roger.

 

I think I would use the numbers in the kit I paid good money for, rather than some info from the internet. Good Luck

 

I've been doing this for a living since 1979.I hate to tell you this ...I have never measured my preload with any device...always by feel.So,in that respect I'm not going to be much help.

 

Thank guys!
Yes, I set the preload as the kit said, but this is the first time I did a set up and have spend some time on internet for info and they all says around 20-22 in/pound.......... But I have to believe the specs that followed with the kit.
//Roger .

 

38-years experience in the gearing business and I'd say the tooth contact pattern shown is very good, providing you have the correct backlash.

 

In my many years doing this professionaly this is an excellent pattern. Run it

 

Just a question regarding my own pattern without starting a new thread.
A friend and I just changed my 8.5 Chevy from 3.43's to 2.73's.
The best pattern we could get with the shims we had available is a little deep on pinion depth and has a bit of a sharp line along the inside edge of the "drive" side. .009 backlash setting.
Now...I just had the T out for a decent run and get zero noise and no real heat from the axle.

The question is...will a bit of extra pinion depth come back to bite me later, or is it one of those deals where if its not giving trouble right away it should be good for the duration?

 

Heavy concentration of load in the flank of either pinion or gear may lead to a scoring and possible failure in time. No pictures of how bad it was, so impossible to tell you how much of a problem it might cause.

 

Yeah...tried to get some pics but for some reason you couldn't see any detail in the paste.
I've seen much worse in pictures of gear patterns but there was definately a bit of a line.
It's just a used set of gears so I guess I'll call them an experiment and p*** judgement at the end of the season!
Time will tell.
Thanks Tagman.

 

On used gears it best to set your pattern on the coast side and if you can match the backlash from the used gear is the best also.

 

Directly toward the exact question asked. It's fine, run it.

 

Thanks Guys!
For opinions and advises, I did tonight the final ***embly on the third member.
I still waiting for some parts, but I hope to do a test drive in about a week.
I'm coming back and tell you if it works or not........... :-/
Bye! // Roger.

 

Hi!
The car is now re***embled again, and did a test run today.

It howls /whine when hit the pedal (acceleration), from zero mph and up...........and is totally quiet with no pedal.
Any ideas what it is........???????

Here is info on Ford 9" third member:

- Yukon Duragrip limited slip.
- Koyo bearings all new.
- Richmond ( I think) ring and pinion 3,50:1 ( came in a white box ,only marked F9350....China made ****?)
- Solid adjustable spacer.
- Moser driveshaft axle bearings.

Specs:
-Backlash 0.008"
-Preload pinion bearing 14 inch/pounds.
-Pattern as above pictures.
-Case preload......like turning in syryp.......or something like that.

Thanks!// Roger .

 

Did you hammer your spanner on the side adjusters? Those side adjusters have to be hammered tight to the bearings, that'll change your backlash if they aren't. You can't see it on the bench but if they aren't hammered and you just put that little keeper in there you'll get another couple thou once you drive it.
Too late now but the 'new' pinion bearing preload is 25ish inch pounds; 'used' pinion bearing is 15ish inch pounds.
That pattern was sweet, pull it out and see what it is now and we'll all learn something.

 

I killed a 9" gear set by not doing exactly what you say.
I didn't realize how tight those side adjusters had to be set to prevent the gear pattern from changing under load!

 

I have driven about 4-5 miles on test run, is it still "new" or is it "used" ??
I 'm going to pull it out and see what it is now.

PS. Before I pull the whole pumpkin out:
Is it possible that the ring gear is to tight to the pinion? If I add let's say about 0.002" to the pinion carrier?
Yes, the pattern and backlash will change too.
But if I remember it right the backlash was in mid range and the pattern almost the same look as pictures.
Any opinions on this?

 

Can't give good answers until you look at the gears. But I'll say you'll be fine. Do us a favor and share pics, this is a great oppertunity for others to learn.

 

I took the pumpkin out 15 minutes ago, went in for dinner...... I'll go out again and check the pattern,backlash ...etc. And look for any wears or damages because there was some small metallic partikels in the gear oil. :-/

 

Inspect as planned. If you find nothing the gear set is possibly lapping it's self and with time the noise will go away. Gear set's made today are no longer pre lapped.

 

Checked the backlash it was 0.008-0.009".
Pattern almost the same (posting pics later).
But the bearing/bearings in pinion cartridge doesn't "feel" right (when turning around in a wise). Going to take it apart and see if bearings are damaged or something ,tomorrow. Maybe I should have more preload than my specs was written........ I set it up at 13-15 inch/lbs preload on new bearings.

Update to come! //Roger .

 

I f you don't remember it being a pain in the *** to set the preload on the pinion bearings... than it may not be correct.

 

Inner bearing has thrust load upon it when power is applied. Outer bearing has thrust upon it during coasting. Since the inner bearing is the one that get pressed on. Maybe some damage to it happened then ? By the way. The best way to check wear pattern is to rotate the gears via the ring gear and not the pinion. This will put more force against the teeth similar but not equal to real conditions.

 

Hi Jonny Gee!
I rotate by the ring gear when do the pattern, also now when searching for damages. Not the pinion.
The inner bearing was not pressed on, I heated it with a Electric heat Gun and it slide into fit smoothly, then let it cooled down slowly.
Maybe wrong way to do it.
// Roger.

 

Rogga, you sound like a very knowledgeable individual by the way you work. Everyone here has given great information. I'm very sure you'll find the problem and solve it. Best of luck

 

Thanks all of you for information to a newbee.

Took it apart and make some shim modification on pinion. Could't find any damages or wears on anything.
Did a testrun today and it feels better but there are noises from the ringgear, I think .
It whines/howls a little ( like a tramcar/trolley/cablecar.....).
Here is pics of the Ring Gear, I think its Richmond but not sure, I bought a kit from Rons Machining Service at Ebay including Yukon diff, Koyo bearings and no name RingGear.
The cheapy RingGear Box looked it came direct from China or something ..........
// Roger .

 

I had not noticed before. Your running a spool ! What is your build exactly ? Back to the noise issue. I said it before (gear set's are not lapped anymore) and since you think your gears are of low quality it very well may be just that. Time will tell as the gears lap together. The noise should become less. In the mean time drive it normal for 30 minutes and let cool. Repeat this a few times as this will make for hardening at the contact point's between the gears. Good luck.

 

Pics after first test run, did a new color pattern.
Look at the pinion at the contact surface, is this normal during Break-In ?

 

Jonny Gee!
No , its not a spool....but I can agree with you on that picture it looks like a spool.
Its just a regular " Hot Rod" Ford 1940 coupe with a Chevy smallblock. Not a racecar.....//Roger .

Ps. I have Gulf LS 80-90w GL-5 oil in it, do you think a little of Lucas Oil treatment in it should do any difference for its life or is it waste of time doing it?