changed posi , now gears make lots of noise!

Posted By: dirt

changed posi , now gears make lots of noise! - 04/22/09 06:49 PM

I had a shop change out my posi unit in my 8 3/4 center section. they were quiet when i dropped them off, just didnt spin both tires, now they are loud. they roar so much you have to talk loud in the car to the other person so they hear you.
i pulled them back out and i am not sure what he did. I have only set up one set of gears and they were not noisy at all.

It is a 741 case 3.91 gears, I cant remember if i had him change the yoke or not but it seems a little loose, the yoke and pinion gear has some play in and out. I didnt think there should be any play there is that right?
I am rebuilding the clutch type posi unit to put back in it and want to fix the noise while i am at it. I have some gear grease ordered to check the pattern.
any ideas?

Posted By: MoparforLife

Re: changed posi , now gears make lots of noise! - 04/22/09 06:54 PM

If it wasn't noisy before it shouldn't be now. Get them to reset it up right. If you wait you won't be able to get it quiet again. There was no reason for them to take the pinion out, all that needed to be removed is the ring gear and the backlash reset.

Posted By: 69Cuda340S

Re: changed posi , now gears make lots of noise! - 04/22/09 07:14 PM

Pinion should be tight, no slack. Like said above you don't need to mess with the pinion to remove/replace the sure grip.

Posted By: dirt

Re: changed posi , now gears make lots of noise! - 04/22/09 07:24 PM

It was 10 years ago and i am just now getting around to reusing it. i only put about 60 miles on it since the shop worked on it.
what would you torque the pinion bolt to?
I may have had him swap the yoke , that would be the only reason to mess with the pinion nut.
I should be able to torque the pinion nut down and set the lash and it should be good i would think,I remember him telling me he had to change the carrier bearings when he installed the other posi unit. but they were supposed to have been new.
what would you set the lash at for used 3.91 gears?

Posted By: stumpy

Re: changed posi , now gears make lots of noise! - 04/22/09 07:43 PM

Just to clear up the terms a little. Chrysler uses the name suregrip. GM is a posi. Some folks get upset when you use a chevy name for a Mopar rearend.

Posted By: polkat

Re: changed posi , now gears make lots of noise! - 04/22/09 07:53 PM

Some 8-3/4" pinions (sorry, I don't remember which) used a crush sleeve between the pinion races as a sort of adjustable spacer. If the old crush sleeve is reused, it is possible to reach the required torque on the pinion nut (I think it is 185 ftlbs) and still have a loose pinion. For a good discussion of setup see this website:

http://www.moparmusclemagazine.com/howto/mopp_0308_mopar_rear_end_gears_set_up/index.html

Posted By: 68Bullit

Re: changed posi , now gears make lots of noise! - 04/22/09 08:09 PM

Man I sold a 741 case 3.91 posi that howled pretty bad. It was a good unit as far as I know, and never put any metal in the gear oil, nor did it have any sharp teeth (and I put WELL over 2000 miles on it). I've heard of many of these same cases with the 3.91 gearset that many people say were fine but just howled and were very loud. It's interesting that it didn't start until you removed the old posi for a good working one.

FWIW, I'd say the guy set it up correctly

Posted By: Chi_Town_Runner

Re: changed posi , now gears make lots of noise! - 04/22/09 08:13 PM

It all depends on the case.

First, only the 489 case used the crush sleeve. The 741 and 742 cases used shim packs to set the pinion depth. On the 741 and 742 case (thanks to Dr. Diff), the pinion nut should be torqued to 140 ftlbs on a 10 spline and 280 ftlbs on a 23 spline.

There should be no play on the pinion. Take it out before you drive it any further and take it back to the guy who built it. The growl you hear could be the rear end eating itself up.

Good Luck,

Frank

Posted By: MoparforLife

Re: changed posi , now gears make lots of noise! - 04/22/09 08:18 PM

FWIW I haave a 4.56 set in a 489 case that is set up right with proper backlash and the pattern is a s near perfect as it can get but you can here it above open headers. It still looks good after several seasons. These gears were that way from day 1 new.
But the point of this poster is is that the gears weren't noisy before but they are after the sure grip switch. This shouldn't be.

Posted By: JohnRR

Re: changed posi , now gears make lots of noise! - 04/22/09 08:38 PM

Quote:

Man I sold a 741 case 3.91 posi that howled pretty bad. It was a good unit as far as I know, and never put any metal in the gear oil, nor did it have any sharp teeth (and I put WELL over 2000 miles on it). I've heard of many of these same cases with the 3.91 gearset that many people say were fine but just howled and were very loud. It's interesting that it didn't start until you removed the old posi for a good working one. FWIW, I'd say the guy set it up correctly

I have 3.91's in my dart , factory gear set,they do not howl , even with the metal particle laced oil because of the POS cone type sure grip .

Did you read all he posted , the pinion is LOOSE , how can you think it's set up correctly if the pinion is loose ?

Posted By: 69Cuda340S

Re: changed posi , now gears make lots of noise! - 04/22/09 08:58 PM

I run 3:91 gears in a 489 case and they don't make any noise.

And yes the fact that it has slack in the pinion bearings is an issue. If retorquing the nut does not fix it it needs to come apart. No crush sleeve in a 741 case, only the 489 had a crush sleeve.

Posted By: 68Bullit

Re: changed posi , now gears make lots of noise! - 04/22/09 09:25 PM

Quote:

Quote:

Man I sold a 741 case 3.91 posi that howled pretty bad. It was a good unit as far as I know, and never put any metal in the gear oil, nor did it have any sharp teeth (and I put WELL over 2000 miles on it). I've heard of many of these same cases with the 3.91 gearset that many people say were fine but just howled and were very loud. It's interesting that it didn't start until you removed the old posi for a good working one. FWIW, I'd say the guy set it up correctly

I have 3.91's in my dart , factory gear set,they do not howl , even with the metal particle laced oil because of the POS cone type sure grip .

Did you read all he posted , the pinion is LOOSE , how can you think it's set up correctly if the pinion is loose ?

"Seems" loose, and "some play" are references that the OP used IIRC.

Yeah, I did read all that he posted, and if you would read all of the entire thread you would see that there is uncertainty whether or not the yoke was even removed or not. The problem started after a working posi was installed, NOT before. No, it doesn't sound right that the yoke is loose, obviously. So, why have other units that were setup entirely correctly howled and made noises similar to what the OP described? That was merely what I was trying to point out.

Posted By: Lefty

Re: changed posi , now gears make lots of noise! - 04/22/09 11:04 PM

Quote:

Just to clear up the terms a little. Chrysler uses the name suregrip. GM is a posi. Some folks get upset when you use a chevy name for a Mopar rearend.

In 1966 Dodge called the clutch type LS in my 66 Coronet a "Power Lock"

Posted By: MoparforLife

Re: changed posi , now gears make lots of noise! - 04/22/09 11:20 PM

Quote:

Quote:

Man I sold a 741 case 3.91 posi that howled pretty bad. It was a good unit as far as I know, and never put any metal in the gear oil, nor did it have any sharp teeth (and I put WELL over 2000 miles on it). I've heard of many of these same cases with the 3.91 gearset that many people say were fine but just howled and were very loud. It's interesting that it didn't start until you removed the old posi for a good working one. FWIW, I'd say the guy set it up correctly

I have 3.91's in my dart , factory gear set,they do not howl , even with the metal particle laced oil because of the POS cone type sure grip .

Did you read all he posted , the pinion is LOOSE , how can you think it's set up correctly if the pinion is loose ?

John I too read is post and the previous posts. That is why I made the far previous statement that there should have been no need to take out the pinion to install the sure grip (if it was or is indeed loose), also made the statement that something was misassembled if it was quiet before and not after, and to get it set up right before driving it and a new wear pattern is established and the noise is irreversable. Again I repeat - But that being that these were quiet they need attention. ASAP.

Posted By: dave571

Re: changed posi , now gears make lots of noise! - 04/23/09 01:40 AM

OK

Unless the bearings have failed, there wasn't enough preload when they changed the yolk(if that was done. The original poster isn't sure)

Remove shims( a little at a time) from behind the outer pinion bearing, and retorque the nut until it has preload again.
Drive it, and see if the noise is gone. Hopefully it is.

If the noise is stil present, it may already be beyond help.

The proper way to install a sure grip carrier on a used set of gears, is ...
1)Measure AND RECORD the backlash setting

2)remove the carrier assembly with the ring gear on it.

3)transfer ring gear to sure grip carrier

4)install new sure grip and gear into center chunk

5)use the adjusters to get the backlash EXACTLY the same as was.

If it's not, the pattern is now off, and it will be noisy.

By not changing pinion depth, and putting the backlash where it was, the original pattern is still intact.

If this procedure wasn't followed, Setting it up, may help, but a worn gear set needs to maintain it's existing pattern to not be noisy. A new pattern means noise.

Pinion depth, should not have been messed with. If the guy who changed the yolk decided to change the depth, and set the pattern up fresh from what it was, it is screwwed, and will always be noisy

Posted By: scratchnfotraction

Re: changed posi , now gears make lots of noise! - 04/23/09 02:40 AM

with stumpy

right there is your prob

you gots a posi were a suregrip should be and its making noise now

sorry,I could not help not saying it

give doctordiff a call he will fix it

Posted By: kzcountry

Re: changed posi , now gears make lots of noise! - 04/23/09 03:32 AM

Quote:

with stumpy

right there is your prob

you gots a posi were a suregrip should be and its making noise now

sorry,I could not help not saying it

give doctordiff a call he will fix it

I agree give Doctordiff a call. He will make it right. I just got my 489 case back yesterday, it had a howl and now quiet as can be.

Posted By: dirt

Re: changed posi , now gears make lots of noise! - 04/23/09 11:45 AM

i did call dr diff, he is sending me a rebuild kit for one of my posi, i mean suregrip units.
I am going to try to set it up myself first and see if it fixes it.

I never knew that posi was a chevy term. everyone around here uses it for any brand of car.

Posted By: RapidRobert

Re: changed posi , now gears make lots of noise! - 04/23/09 12:41 PM

Quote:

with stumpy
right there is your prob
you gots a posi were a suregrip should be and its making noise now

Life is good

Posted By: DoctorDiff

Re: changed posi , now gears make lots of noise! - 04/23/09 01:26 PM

Posi has become a generic term, like Allen wrench or Crescent wrench.

Technically, Spicer sourced Powr-Lok (Power-lock) traction differentials were used from '57-'68 in Mopar 8 3/4" rears. Chrysler called these Sure-Grip.

Powr-Loks were also used from '57-'64 in Chevy passenger car rears. Chevy caled these Posi.

Posted By: JS29

Re: changed posi , now gears make lots of noise! - 04/23/09 02:33 PM

Mona Lisa Vito: The car that made these two, equal-length tire marks had positraction. You can't make those marks without positraction, which was not available on the '64 Buick Skylark!
Vinny Gambini: And why not? What is positraction?
Mona Lisa Vito: It's a limited slip differential which distributes power equally to both the right and left tires. The '64 Skylark had a regular differential, which, anyone who's been stuck in the mud in Alabama knows, you step on the gas, one tire spins, the other tire does nothing.
[the jury members nod, with murmurs of "yes," "that's right," etc]
Vinny Gambini: Is that it?
Mona Lisa Vito: No, there's more! You see? When the left tire mark goes up on the curb and the right tire mark stays flat and even? Well, the '64 Skylark had a solid rear axle, so when the left tire would go up on the curb, the right tire would tilt out and ride along its edge. But that didn't happen here. The tire mark stayed flat and even. This car had an independent rear suspension. Now, in the '60's, there were only two other cars made in America that had positraction, and independent rear suspension, and enough power to make these marks. One was the Corvette, which could never be confused with the Buick Skylark. The other had the same body length, height, width, weight, wheel base, and wheel track as the '64 Skylark, and that was the 1963 Pontiac Tempest.
Vinny Gambini: And because both cars were made by GM, were both cars available in metallic mint green paint?
Mona Lisa Vito: They were!
Vinny Gambini: Thank you, Ms. Vito. No more questions. Thank you very, very much.
[kissing her hands]
Vinny Gambini: You've been a lovely, lovely witness.

Posted By: plumebody

Re: changed posi , now gears make lots of noise! - 04/23/09 03:44 PM

My Cousin Vinnie

And she's HOT

Posted By: CYACOP

Re: changed posi , now gears make lots of noise! - 04/23/09 05:52 PM

Quote:

My Cousin Vinnie

And she's HOT

Pic?

Posted By: GomangoCuda

Re: changed posi , now gears make lots of noise! - 04/23/09 06:17 PM

Quote:

Quote:

My Cousin Vinnie

And she's HOT

Pic?

Just google Marisa Tomei.

Posted By: scratchnfotraction

Re: changed posi , now gears make lots of noise! - 04/23/09 07:00 PM

Posted By: dirt

Re: changed posi , now gears make lots of noise! - 04/25/09 03:37 PM

the yoke was loose!
that could be why the gears made so much noise.
what should it be torqued to? 741 case course spline?

Posted By: Chi_Town_Runner

Re: changed posi , now gears make lots of noise! - 04/25/09 06:02 PM

Posted above:

Quote:

On the 741 and 742 case (thanks to Dr. Diff), the pinion nut should be torqued to 140 ftlbs on a 10 spline

Frank

Posted By: dirt

Re: changed posi , now gears make lots of noise! - 04/25/09 11:18 PM

Its tightened up now, rebuilt the suregrip and took it for a test drive and it worked great. 2 of the disc were broke in the suregrip.
it spins both tires and is quiet again.