Author Topic: 9 inch open differential  (Read 40025 times)

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Ratbird

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9 inch open differential
« on: May 28, 2014, 09:51:21 AM »
A couple of years ago I bought a 9 inch open differential (3.89) from a very knowledgeable guy who specializes in rear ends. It was out of an 1968 F-100 and was supposed to be an "open rear end. (It was just to get me rolling)
This past weekend I wanted to video it doing a burnout. After the burnout I went back and looked at the tracks, to my surprise both tires were spinning. I had about 100 foot long two tire burnout. Is that possible with an open rear end? I was told that power goes to the wheel that is spinning, or does not have good traction.
 
The reason I ask, and the reason I did the burnout, was because I am getting ready to buy a 4.11 trac loc 3rd member and I wanted to compare traction.

thx, Dave   
1959 T-bird - rat kind of a thing
FE 410ci bored .030 over, 4 sp toploader
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jayb

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Re: 9 inch open differential
« Reply #1 on: May 28, 2014, 10:23:58 AM »
Sounds like it does have some kind of traction lock unit in it.  You can tell for sure by jacking up the back of the vehicle and rotating one of the rear tires by hand.  If it is an open rear end, the other rear tire will spin in the opposite direction.  If it has some kind of positraction or traction lock setup, both tires will rotate in the same direction.
Jay Brown
- 1969 Mach 1, Drag Week 2005 Winner NA/BB, 511" FE (10.60s @ 129); Drag Week 2007 Runner-Up PA/BB, 490" Supercharged FE (9.35 @ 151)
- 1964 Ford Galaxie, Drag Week 2009 Winner Modified NA (9.50s @ 143), 585" SOHC
- 1969 Shelby Clone, Drag Week 2015 Winner Modified NA (Average 8.98 @ 149), 585" SOHC

   

Lenz

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Re: 9 inch open differential
« Reply #2 on: May 28, 2014, 10:26:41 AM »
Well, I've never heard of anything like that happening with an "open" rearend, especially if you laid it down for 100 feet.  In fact, I'd like one of those myself :), the price would be right.  Jay has the quick check that doesn't fail, do you remember what the internals looked like?
Len Zielinski
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machoneman

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Re: 9 inch open differential
« Reply #3 on: May 28, 2014, 10:32:03 AM »
Yep, you lucked out as no way would an open rear burn both tires, let alone 100'  :)
Bob Maag

Ratbird

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Re: 9 inch open differential
« Reply #4 on: May 28, 2014, 11:37:21 AM »
If I jack it up and turn a tire by hand the other side turns in the opposite direction, thus an open differential.

In the burnout the car even started to slide sideways with the slope of the road. Here's the only pictures that I have. The differential picture of the pumpkin on the little floor jack is probably the best. It's about 2/3's the way down.

https://plus.google.com/photos/101492851059660555641/albums/5796586478747315697?banner=pwa&authkey=CJSKjNbR6eunsgE

Sure is weird, wish I would have taken a picture of the burnout tracks. BTW, I had on stock street tires when I did the burnout, not the cheater slicks in the pictures.

thx, Dave J
1959 T-bird - rat kind of a thing
FE 410ci bored .030 over, 4 sp toploader
pure fun

Heo

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Re: 9 inch open differential
« Reply #5 on: May 28, 2014, 01:56:12 PM »
Maby someone made one to many one Wheel
burnouts and welded the spidergears to the
axle in the differetial



The defenition of a Gentleman, is a man that can play the accordion.But dont do it

machoneman

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Re: 9 inch open differential
« Reply #6 on: May 28, 2014, 02:52:47 PM »
True on the failed spiders. Still, very odd that it's not a OEM Ford Traction Lock (a.k.a. Trak-Lok) as I've also never seen an open rear end spin both tires. Could also have a poor man's mini-spool with welded gears (welded on purpose) but it would still spin both the same way. Very strange! 

http://www.fourwheeler.com/how-to/transmission-drivetrain/131-0901-welding-spider-gears-locking-differential-4wd/
« Last Edit: May 28, 2014, 02:54:54 PM by machoneman »
Bob Maag

Ratbird

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Re: 9 inch open differential
« Reply #7 on: May 28, 2014, 05:10:12 PM »
Agreed, very strange.
I'm going home in an hour and will try it again.

Stay tuned.........
1959 T-bird - rat kind of a thing
FE 410ci bored .030 over, 4 sp toploader
pure fun

Ratbird

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Re: 9 inch open differential
« Reply #8 on: May 28, 2014, 08:28:12 PM »
Well holy shiitake sauce, it must be a trac-lok. I just laid down two 70 - 80 foot burnouts and got the skid pictures to show it. Not only that, but I jacked up the rearend and turned either wheel and the opposite wheel did NOT turn.
I positively remember turning one and the other rotating the opposite way before. However, that must have been before I put in the 3.89. So the guy who sold me the current pumpkin was mistaken and he sold me a trac-lok. That would explain a lot of things. For one, the old 390 felt powerful enough, but it would barely spin the cheater slicks, which at the time I thought was a one wheel wonder. That was because the clutch was stock, and the rear end was a trac-lok.

Man, I'm sorry to have bothered everyone with yet another rookie mistake.

I'm guessing that, because the one wheel will turn (while jacked up and out of gear) and the other doesn't reverse, then I must have the clutch type thingy in there - would that be correct?

Dave J     
1959 T-bird - rat kind of a thing
FE 410ci bored .030 over, 4 sp toploader
pure fun

66FAIRLANE

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Re: 9 inch open differential
« Reply #9 on: May 28, 2014, 09:18:27 PM »
Even with a Traction Lock (clutches) the wheels still turn together when jacked up. I have sometimes seen open wheelers lay two stripes, but not consistently.

frankenfords

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Re: 9 inch open differential
« Reply #10 on: May 28, 2014, 10:10:50 PM »
Well holy shiitake sauce, it must be a trac-lok. I just laid down two 70 - 80 foot burnouts and got the skid pictures to show it. Not only that, but I jacked up the rearend and turned either wheel and the opposite wheel did NOT turn.
I positively remember turning one and the other rotating the opposite way before. However, that must have been before I put in the 3.89. So the guy who sold me the current pumpkin was mistaken and he sold me a trac-lok. That would explain a lot of things. For one, the old 390 felt powerful enough, but it would barely spin the cheater slicks, which at the time I thought was a one wheel wonder. That was because the clutch was stock, and the rear end was a trac-lok.

Man, I'm sorry to have bothered everyone with yet another rookie mistake.

I'm guessing that, because the one wheel will turn (while jacked up and out of gear) and the other doesn't reverse, then I must have the clutch type thingy in there - would that be correct?

Dave J   

If one wheel turns, but the other does NOT turn, when you jack it up, and when you hammer it both wheels spin equally, sounds like a Detroit Locker to me. That would be the ultimate score. Does it make a ratcheting sound during low speed turns when you're off the gas? Does it squeal the inside tire during turns when you're giving it even light amounts of pedal?

I have heard of 4 pinion open differentials being shimmed to tighten the spider gears to make a 'poor man's' limited slip, but if that was the case, the other wheel would turn the opposite direction when you spun one side, like any other open dif. If both tires spin the same direction, that would tell me clutch type limited slip.

Ratbird

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Re: 9 inch open differential
« Reply #11 on: May 28, 2014, 10:57:06 PM »
Hm, well I don't know what to make of it now. I'll try to upload the video and the pictures tomorrow evening.
The guy that sold me this is what I would call an expert. This is his main work, and he has a lot of years experience. I was told by more than one person that he is one of two guys in Albuquerque that can really build precision, quality, diffs.

I'll try to contact him tomorrow and see what he thinks. He has a trak-lok 4.11 he will trade me for mine and $400. It's not rebuilt, but he said it's in good shape. He said it'll be a little loud, but with my Ratbird I won't be able to hear a thing.

I know mine's not a locker because I've done some 4 wheeling in the mountains, and hauling firewood. I've been in my truck when I hit pavement and forgot to unlock the hubs - thus, I know how they bind and bite when cornering.

Stay tuned again!
Thx to everyone again.
1959 T-bird - rat kind of a thing
FE 410ci bored .030 over, 4 sp toploader
pure fun

Cyclone03

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Re: 9 inch open differential
« Reply #12 on: May 29, 2014, 03:41:47 AM »
The 4 pinion diff under my Mustang would spin both tires 50ft or so.
In neutral both rears turned the same way , but holding drive shaft opposite.

Trac Loc turns one wheel if drive shaft is held.
Lance H

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Re: 9 inch open differential
« Reply #13 on: May 29, 2014, 07:57:03 AM »
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 
1959 T-bird - rat kind of a thing
FE 410ci bored .030 over, 4 sp toploader
pure fun

mlcraven

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Re: 9 inch open differential
« Reply #14 on: May 30, 2014, 06:59:45 PM »
Careful...he might ask for it back!
Michael