9 inch open differential

[frankenfords]

When I jacked it up and turned the drivers side wheel, the passengers side wheel started to turn in the opposite direction for about 1/4 of a turn - then it stopped. The drive shaft was turning. Then I turned the passengers side and the drivers side did nothing. Went back to the drivers side and turned it and the passengers side did nothing. Each time the drive shaft was always turning.
I'll call the guy who sold me it and see what he says. Might be today, but most likely this evening.

thx, Dave J

Sounds like an open differential based on the description above. Given how it's working for you, meaning two equal patches of rubber, I'd be reluctant to swap it out

[Ratbird]

OK, sorry it took me so long to get back to this, I was on a short vacation to Colorado with the wife.

I talked to the guy I bought it from. He said that he's seen this happen before on open differentials that have been run hard, or worn out from burnouts, miles, etc. I think he said if the shims (or the bearings) get too hot and wear out the diff can sometimes lay down two tracks on a straight line burnout, but can also act as an open around corners. Sounds like it would be a sweet deal if you want a posi, BUT, the trouble is that it won't do the same thing consistently.

So he has a 4.11 that he'll swap me for my 3.89 for $400. It needs bearings ($80) and a yoke ($50), labor ($175). So I can get a decent (but noisey) 4.11 trac-lok for $705. Does that sound reasonable?

Dave J   

[ScotiaFE]

Not if it is noisy. The Trac Lok  should be as quite as church mouse.
Something is wrong with it if it is making noise.

[machoneman]

Sounds like your guy knows not of what he speaks. As noted, a Trac-Loc is quiet unless it's torn-up while a Locker will make noise, mainly clunking, on turns. Again, as to a open rear laying down twin tracks, hard to fathom, for sure. Mechanically, by what method can an open rear spin both tires? Does he need glasses when he does a rear end?   

[Lenz]

So OK, it's time to take this thing apart .  I'd like to see what's on the inside.  Sorry Dave, know I'm talking about extra work but as someone somewhere once said, "a picture is worth a thousand words".  Then again, you could just keep layin' down those double stripes until you convince yourself that you have a Trak Loc under there.  Me, that's what I'd do .  I sure wouldn't be eager to swap $700+ for something that needs work.  No matter what you decide, once you get what you have now out into the light of day all questions will be answered (if it's working, quiet and consistent I'd leave it in and run the @^%& out of it).  The guy you bought it from is suggesting that he sold you a shot rear end that doesn't make noise and acts like a Trac Loc.  I do not know all the details or your supplier, but something just don't add up .

[Dr Mabuse]

My '66 Galaxie had a 4.57 open differential, and I always got an equal burn because I had Airlift air bags in the rear springs, with #5 in the left rear, and #10 in the right rear.

I would never install a Trac-Loc in a 9". They will burn up clutches and also the OEM cases tend to crack. They are not a good, or durable design, especially for 4x4's, or drag racing.

An Eaton Detroit Locker, or Detroit Truetrac are much better choices.

[chilly460]

So he has a 4.11 that he'll swap me for my 3.89 for $400. It needs bearings ($80) and a yoke ($50), labor ($175). So I can get a decent (but noisey) 4.11 trac-lok for $705. Does that sound reasonable?

Dave J   

Doesn't seem like a good deal at all, I saw few rebuilt TrackLok rears, complete for $400 this weekend. 

[KMcCullah]

Dang for $700+ you could do an ARB Airlocker and end up with an onboard air compressor to boot. Hell Dave it's a rat rod, just weld the spiders and be done with it. 

[Ratbird]

Hm, I sure wish I knew something, (anything) about differentials. So just to refresh, the car is a Ratrod kind of look, but the engine, transmission, clutch pressure plate etc is completely and professionally rebuilt. Even though it's a 59 T-bird, it has power (front) disk brakes. It's mainly a street car, but I want to drag it maybe once a year. (I just have to be able to show a drag strip slip that proves a mid to low 14's time at a mile high) Yes, I have the fever. My name is David, and I'm a dragoholic. ;0) 

Here's what little I know; please let me know what you think about each.
He said the ring and pinon gears were slightly pitted (due to rust) and that will make them noisy. But, he said they will still be plenty strong for a 400hp motor and it won't affect the strength or performance. (true or false?)

I think what he's saying is that the spider gears can get worn and burnt, and start to act like they are welded, thus it sometimes will lay down a two stripe burnout, but on a turn they break free and act as an open. Problem is, it's a crap shoot each time. (true or false or maybe?)
I said to him, well if that is true, then you sold me the 3.89 that was supposed to be noisy but solid, yet it didn't last. He said, that's because an open differential is not meant to be doing burnouts, and the burnouts are what most likely trashed it (true or false?)

He said the Ford diff clutches last pretty long. They have a larger diameter than a Chevy. Chevy's are no good. He said this 4.11 clutch still has plenty of the checkered pattern on it which means it will last quite a while. (true or false?)     

Chilly, where did you see rebuilt Trac-loc's for $400? I found this on E-bay, http://www.ebay.com/itm/FORD-9-NINE-INCH-REAR-GEAR-TRAC-LOC-POSI-THIRD-MEMBER-28-SPLINE-OR-31-SPLINE/151323330908?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222008%26algo%3DSIC.MOTORS%26ao%3D1%26asc%3D23309%26meid%3D7503784206041329585%26pid%3D100005%26prg%3D9834%26rk%3D3%26rkt%3D6%26sd%3D161288632259&rt=nc
Seems like a better deal than mine as it's completely rebuilt, and I can sell my worn out 3.89 and get some money back.

Len, you are exactly correct. I can guess and guess forever, but I need to pull the pumpkin anyway if I'm going to be getting a posi (trac-lok). I can take pix, post them, and you great gentlemen will have a lot more than my lame explanations to go on. It's going to be a while though. Right now I'm in the middle of replacing the fuel lines with 3/8's inch. Bending this stuff is a lot tougher than bending conduit! 

Regards and thanks to all, Dave J.
 

[chilly460]

Saw them at Carlisle.  I actually picked up a complete Detroit Locker 3.70 third member for $525, that Ebay unit is out of line IMO. 

[jayb]

I would say his first statement about pitted gears may be true, although it is more likely that the gears are noisy because they are worn.  His second statement about the spider gears being worn and acting like they are welded sounds like BS to me.  However, he may be on the right track because if the shafts that the spider gears are riding on are worn, maybe they could jam and lock the wheels together in some situations.  As far as burnouts trashing a one wheel wonder (open rear end), its always possible, but they should take some of that abuse anyway.  My experience with Ford clutches is that they do last a long time, until you start doing burnouts; then you can burn them up in a hurry.  If there is a checkered pattern on the clutches there is still clutch material present,so they have a while to go before they give up completely.

Two words:  Detroit Locker   

[cjshaker]

I was just going to reply when Jay popped in. I have to agree with every word he said. And I'll add that me and friends (when we were young) used to do "one wheel peels" in every conceivable way possible, on a regular basis, in all sorts of Ford cars and NEVER did we have any rear troubles except for the backlash that comes from a hundred thousand plus miles of use. He's also right on with Traction Loks, while they work, when you try to treat them like a posi the clutches have a very limited lifespan.

In my opinion, when you are purchasing a rear differential from somebody who rebuilds it with nearly all used parts, then you are going to get marginal performance and lifespan at best. Especially when those parts are robbed from many different used pieces that had already seated and worn into their original assemblies. And I get the feeling all those parts are robbed from junkyard rears that likely already had 100,000+ miles. It's like using used pistons and rings from a wore out engine in a fresh rebuild, it just don't work out well.

But mainly I agree with this statement 110%. This will end your problems forever

Two words:  Detroit Locker   

[Ratbird]

Thanks again gents.
What do you mean by "out of line" Chilly? Do you mean there's a possibility they are made with low quality parts and steel? I've heard that it takes someone with a lot of experience to be good at building rearends, and it concerns me too that these things might be mass produced.

Jay, the rearend is from an axle a guy traded him for some work. When he opened it up he found out it was in need of repair, thus the pitted gears etc. I don't convey what he has told me very well, but I'm guessing he was talking about the shafts for the spider gears is why it sometimes lays down two tracks.
 
So is a Detroit locker for strip only though? I want something that is street compatible. Do you guys know of a good source for a locker and how much that might cost me?

regards, Dave

 

[jayb]

Detroit Lockers work great on the street, in my opinion anyway.  You can buy them online at Summit for around $550; see the link below.  These are the newer "soft lockers" that are quiet, yet positively lock the rear end.

http://www.summitracing.com/parts/dtl-187sl17b/overview/

[Jim Comet]

Check out quickperformance.com I have never used them but they list many choices. I may give them a try when I get my new center section this fall. Jim