9” trac-loc rebuild experts?

[71mach351]

I bought a used tracloc diff off eBay a couple years ago.  Seller claimed it was rebuilt.  I installed it and it had a whine above 40mph.  This year I decided to pull it and have it checked by a local performance shop.  I had them rebuild it again with new gears , bearing , everything.I put back in and it whined even louder.  The shop said they worked with their parts supplier and said the gears were incorrectly manufactured.  They pulled it again and installed a different brand of gears.  All the rebuild specs are dead nuts.  Now it makes a different whine.  

Can the housing be worn out so when installed in the car things just don’t mesh right? I’m at a loss and the shop is too.

Have any of you rebuilt a diff and just can’t get it quiet?

 

[Kilgon]

I'm not an expert but I have rebuilt a few over the years. A couple of quick questions - does it whine all the time at all speeds, or just higher speeds. Also does it whine when you coast or are slowing down? If you can answer these might be able to give you some idea of what's going on. Also, are you for sure it from the rear end and not one of the axle outer bearings?

 

[Don C]

Does it whine all of the time or just on acceleration, deceleration, coasting, or going around corners?

It's possible the housing was damaged or machined wrong so the pinion doesn't align correctly with the ring gear.

Were all of the bearings and races replaced?

Did you see what the contact patterns were on the ring and pinion?

 

[TommyK]

The case is prone to cracking at the pinion pilot support bearing. I had one do it. It was hard to see.

 

[Jeff73Mach1]

The cases can also distort if used with big horsepower-hard to detect sometimes

 

[SVO2SCJ]

You have invested MUCH time and money on this (and I get it) YOU WANT IT RIGHT !!

I only use ONE builder now (as the OLD local 9" guys are gone - and that is in Detroit) !! Call ALAN (you will be glad you did)

https://8and9inchfordrears.com/

Mark

P.S. While he builds date coded detailed units for me - HE can talk the talk of modern Tru Trac, Lockers and even build the Alum Strange (oerformance) or Mark Williams 10" Top Fuel hogs !

 

[73pony]

The guys at quick performance in Ames, IA do really good work as well.

www.quickperformance.com

 

[Stanglover]

I'm interested in the replies that come back on this subject.

 I plan on pulling the rear axle out of my 71 Mach 1 soon to have the axle reconditioned. It is the only part on my car that has not been done yet.

The plan is strip it, clean it and replace all bearings and races and seals, then make it look pretty and put it back in with a new set of Eaton Springs 152lb leaf springs (Boss). I'm scrapping the Grab-A-Trak 4 1/2 leaf if I can't get then reshaped for the correct free arc, but that's another story.

Back to the axle. It is a 3.25:1 open dif and for the driving I do, I'm ok with that. However there is a local guy who specializes in rebuilding rear axles. mainly Chevy, but has lots of experience with Ford. He has a Trac-Lok center section already done and offered it to me for 300 bucks Cnd. but use my 3.25's with it. My problem is do I really want it or is the open dif good enough? At present, there is no whine or noises from the rear end, so am I inviting problems by installing the Trac-Lok?

I have a buddy with a 73 Torino. It has a trans-planted 429 in it which may be part of his rear dif problems. A different local transmission and rear end guy put in 2 or 3 sets of Dana gears and every time they whined like crazy. Finally this person gave my buddy back his money and gave up on it. My friend then took it to the guy I plan on using and he installed a True-Track center section and problem solved. My problem is I can't afford that option.

So that's why I am interested in reading the replies to this post.

Geoff.

PS, no intent to hi-jack this thread, just interested in others opinions on the original post. Hope no offence is taken.

 

[71mach351]

The first set of gears whined starting at about 40 mph. Apply light throttle and you’d start to hear it. It was a constant drone on the interstate but become quieter as you coasted. With the new gears, it had on consistent hum fron dead stop and up and then continuing as you slow down.

All bearings and clutches replaced. Axle bearings also replaced.

I didn’t see the pattern on the second set of gears since I made them pull and replace after the first time.

The first rebuild I installed. It had a good contact pattern.

At this point it would not be cost effective to ship it to anyone to go through it again. It would be cheaper to buy a new aftermarket tracloc.

 

[Don C]

That is assuming it is the TracLok making the noise. When driving in a straight line the actual helical gears that provide the traction control should not be turning, unless you have different size tires or one is very low on air.

My guess is that the pinion/ring gear angle is wrong.

 

[Kilgon]

Unfortunately you are at a point of having to remove it no mater what is causing the problem.  I would start by pulling it out and checking the mesh pattern on the ring and pinon to see how the pinon is contacting on the drive and coast side of the ring gear.  You can use white grease as a marking paste if you need to.  

If  you can verify that ring and pinon is adjusted right then you can decide on your next move.  Odds are I think you will find out they are not properly adjusted.  If it is out and you want to try to tackle the job yourself Bad Shoes Productions makes an excellent video on rebuilding a 9".  http://www.badshoeproductions.com/

 

[71mach351]

That is assuming it is the TracLok making the noise. When driving in a straight line the actual helical gears that provide the traction control should not be turning, unless you have different size tires or one is very low on air.

My guess is that the pinion/ring gear angle is wrong.

So Don, if the thing is all set up correctly on the bench and the pattern on the gears is good, could a cracked pinion support cause the angle to change under load causing noise?

Kligon,  Don't you need a press for some parts of the rebuild?

 

[Don C]

The crack itself wouldn't be the cause of the misalignment, but whatever caused the crack probably also tweaked the case.

Yes, you will need a press and a bearing separator/puller. You'll also need something to hold the u-joint yoke while you loosen the pinion nut. I use a big stilson wrench that has a 3-foot long handle and cover the jaw teeth. You'll also need a micrometer, or digital or dial caliper, and a dial indicator.

It also helps to have a carrier removal adapter for a floor jack, that thing is heavy, if it drops and your hand is in the way you'll go to the hospital. Really helps when you install it. A holding fixture for the bench also really helps.

 

[71mach351]

The crack itself wouldn't be the cause of the misalignment, but whatever caused the crack probably also tweaked the case.

Yes, you will need a press and a bearing separator/puller. You'll also need something to hold the u-joint yoke while you loosen the pinion nut. I use a big stilson wrench that has a 3-foot long handle and cover the jaw teeth. You'll also need a micrometer, or digital or dial caliper, and a dial indicator.

It also helps to have a carrier removal adapter for a floor jack, that thing is heavy, if it drops and your hand is in the way you'll go to the hospital. Really helps when you install it. A holding fixture for the bench also really helps.

Yeah, that's what I thought.  That's why I had the "professionals" do it.

Unfortunately they got it back to me so late in the season I had to put it away for the winter.   They said they would take care of me in the spring.  We'll see how that goes.

 

[Kilgon]

That is assuming it is the TracLok making the noise. When driving in a straight line the actual helical gears that provide the traction control should not be turning, unless you have different size tires or one is very low on air.

My guess is that the pinion/ring gear angle is wrong.

So Don, if the thing is all set up correctly on the bench and the pattern on the gears is good, could a cracked pinion support cause the angle to change under load causing noise?

Kligon,  Don't you need a press for some parts of the rebuild?

Yes a press is needed.  Also a dial indicator with a magnetic base and bearing splitter. Can pick up a low cost press at harbor freight for about $90 or so.  If you do a lot of mechanical work they are worth having.  Another possibility that might be causing your current problem is the preload on the pinon.  If they preloaded the pinon using a crush sleeve and the nut got backed off on the yoke it would allow for the pinon to dive to deep when accelerating and be pushed back out when coasting causing whining issues and extreme gear wear.