9 inch open differential

[Ratbird]

The Detroit locker looks great Jay, and they have a $50 rebate right now so my 28 spline would be $499.
But then I need the ring and pinon to make my 3.89 a 4.11, plus I'd have to pay someone to do the work.

The ones Jim pointed out from Quickperformance.com are $525 for any axle spline. A complete center section with 4.11 gears and the Detroit locker is $975. That one says it's good for up to 400 HP. I'm right around there, however if I ever want to move up to a 445 stroker etc I'll have to have a better case - nodular or aluminum takes it up another $700.

My head hurts.........I need to rethink this plan.

Hell, if I decide I'm going to do a 4.11 detroit locker, then I might as well take the one I have now (the 3.89) and weld it up as a drag setup, and run it ragged this summer.   

[chilly460]

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.

I meant that $700 for a traction lock third member is out of line with what I saw for prices at Carlisle.  I saw $375 on one, and $400 on several more, before haggling.  Granted, I don't know particulars if they were used gears or what, but even with new gears it would seem they'd be considerably cheaper than $700.  These are plain iron cases. 

I've run Detroits on the street, granted in heavy trucks, but they weren't too bad IMO.  They have a bit more lash so you have to be smooth on/off the throttle at low speed, but otherwise I found the driveability difference minimal.  I like that fact that they're bulletproof and simple. 

I picked up a complete 3.70 Detroit Locker rear at Carlisle for $525, used locker, plain case.  Lots of guys run used NASCAR detroits without issue, they run $200-225 on Ebay so that's a consideration if you're trying to save some cash. 

[KMcCullah]

Epay has a bunch of complete used 3rd members. Something else to make your head hurt.  Your 28 spline axles seem to be an issue as most I looked at were 31 spline units. I'm always up for a used part if it saves me a buck.

http://www.ebay.com/itm/5-67-9-Inch-Ford-3rd-Member-31-Spline-Race-Car-Hot-Rod-/171355500574?pt=Motors_Car_Truck_Parts_Accessories&hash=item27e595701e&vxp=mtr

http://www.ebay.com/itm/5-29-Ford-9-Inch-3-Rd-Member-31spline-/171355494104?pt=Motors_Car_Truck_Parts_Accessories&hash=item27e59556d8&vxp=mtr

[fastback 427]

I just picked up a Yukon aluminum thru bolt, Richmond gears, Daytona aluminum support, and bearing kit for under 600 at quickperformance. The prices are great shipping was a day early. I reused my spool. The guy that set up mine said the Yukon quality was as good as the high end mark Williams case.

[Ratbird]

"Yukon aluminum thru bolt, Richmond gears, Daytona aluminum support"

You guys might as well be speaking German.

Quickperformances web site seemed very user friendly. Maybe I'll give them a call soon and see what they recommend. I'm sure they can explain things to me faster over the phone.

So is a "mini spool" the same as a Detroit locker?

[fastback 427]

No. A spool keeps the axles turning the all the time. Lockers go in and out of "posi track". I run a a spool on the street with no problems but many don't like them on the street. What I was getting at with the Yukon case etc, was that its good for 1200 HP at a low cost. You can also get a nodular case from him around $240.

[Ratbird]

I talked to Mike at "quickperformance". He said I should consider getting some 31 spline axles if I ever want to go up past the 400hp range. Better to do them when I do the third member as opposed to spending money twice. I have to agree, it'll be money saved in the long run. It's going to be a while before I get the bucks saved up though.

He also said that my scenario of an open acting like a posi is very possible, it's also telling me that something is really wrong in my differential.

After i get done with my fuel lines (hopefully this weekend) I'll pull that 3rd member and see what's going on inside. Any advise (or even instructions) on how to weld the thing as a complete locker? I'm sure there are some video's on youtube.

thx, Dave J   

[machoneman]

Don't weld the spiders. There is a reason why NHRA and other drag racing associations forbid vehicles with welded spiders from competing on a real drag strip. If (more like when) the welds give up or the spiders shatter, the instantly driven side will easily put you into the guard rail. This is the same reason why spools require aftermarket axles; no longer are 31 splined OEM Ford axles still allowed with a spool. 

2:11 REAR END
Welded spider gear rear ends prohibited in all classes. Four wheel
drive permitted per class requirements. Aftermarket axles
and axle-retention device mandatory on Top Fuel, Funny Car,
Pro Stock, Top Alcohol Dragster, Top Alcohol Funny Car, Comp,
Super Comp, Super Gas, Super Street, and 10.99 or quicker E.T.
cars; also mandatory on any car (regardless of class or E.T.) with
a spool.
2:12

[Ratbird]

Thanks Bob, yeah, I don't plan on taking it to the track until I get a proper rear end in it. For that matter, I want to replace all the front end bushings and get a good alignment first too.

The weld up would be just to get by with a drivable car for now. If I open it up and the pins (or whatever they are called) for the spider gears are shot I thought maybe I can have it welded for now.

I'm not even sure how that works, but I found a local guy who teaches auto mechanics at the local northern NM college and he rebuilds trannys out of his home shop. I'll take to him or at least pick his brain.

thx, Dave

[Heo]

The problem with open diffs and one Wheel burnouts
(low oil lewel ads to the problem)
Is the spidergears seizes to the pin that holds them (steel against steel)
Now it drives both wheels
And the pin starts to rotate and cut the pin that is there
to hold it in place. And the pin starts to destroy the hole
for it in  the diff and you get a play thats gett bigger and bigger.
By now the diff is junk.
Finaly the pin for the spider gear breaks and the car wont move
Maby you still can save your diff with a new pin and two spidergears

[Ratbird]

Thanks Heo, your explanation is actually one that I can understand, and makes sense. Like I said, I know next to nothing about diffs. Is it very difficult to remove the spider gears? And would I need any special tools to put new ones back in? (adjustments, shims, etc?)

If I take that route I can surely sell it and re-coupe some money for a detroit locker.

Dave 

[Heo]

I dont remember but i Think on the 9 inch you
have to open up the diff to change the spidergears
you have to remove the diff from the senter section
but no problem just ordinary hand Tools
Be careful to not change adjustment sidewise on the
diff and your fine
You understand when you see inside the centersection
two big..."nuts" to adjust the diff from side to side

Hard for me to explain in English but i Think you figure it out

[Ratbird]

Thanks again Heo, when I eventually get it out I'll look at the gears and pin and see if they are in need of replacing. Hopefully it's not beyond repair. I'm quite good with mechanical stuff, but don't own any micrometer's and other tools, etc. that are needed to do a lot of car stuff. I'm OK up to a torque wrench and that's about it.

It's midnight where you are, have a good weekend!

[KMcCullah]

How about some good pics of this ill advised procedure. And a hint..... mig or rod (3/32 dia 7018 or 6010) works fine. Just make sure you preheat before you weld em. 200-250 deg will do. After welding let it cool slowly. Wrap the whole center section with a thick chunk of pink attic insulation to help slow the cooling process. 

https://www.google.com/search?q=9+inch+welded+spider+gears&tbm=isch&tbo=u&source=univ&sa=X&ei=FHabU8-3K4mzyASftIFg&ved=0CC4QsAQ&biw=1600&bih=805

And don't weld the wrong gears. I noticed a pic of a ring and pinion welded together. Don't do that! 

[Heo]

Or you can make a limited slip like in a Volvo 164
my son bought.
They had stuffed a pair of jeans in with the spidergears