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Discussion Starter #1
Looks like this differential didn't make it. The worst part was that it took out a perfectly good set of 4.10 gears! A hard shift to 2nd did it in, though I suspect the diff may have already been weak.



After taking out the pumpkin, it appears the rear bushings that hold the pumpkin onto the IRS frame were badly worn. Not exactly sure what went first, though, the carrier or the carrier bearing cap.

Anyone have ideas?

I'm thinking the worn bushing allowed the pumpkin to move, placing more strain on the carrier due to the extreme alignment angle between the half-shaft and carrier. Now I'm just trying to figure what went first, carrier housing or bearing cap. Probably the cap. I did seem to recall some differential noise (higher speeds) about a month ago, while driving on an extended trip. Didn't act up in town though, so I didn't give it a second thought.

More pics:

Pumpkin internals close up
Broken parts detail
Carrier housing (what's left of it) crack
Something tried to punch it's way out

This time I figured what-the-hell, found some used 4.56's and slapped them in. I must say, it is quite a fun ride around town now! Just wish I had a 0.5 6th gear. Hmm, might have to take a deeper look into swaping out the 5th/6th gear counter shaft and getting a higher 6th gear so I can keep these 4.56's in there :D


__________________
99 Cobra coupe heavily modded daily driver!
(I do all my own work, including engine, transmission and differential rebuilds)
Returnless fuel, T-56, built motor w/cams, P&P heads (just to name a few mods)
570rwhp/466tq on only 10.5 psi boost
Official 1/4 mile: [email protected] 1.81 60' limited only by the IRS and road race suspension
A 10 sec capable car!

A Cobra on the surface, a Viper underneath!

Gauges - zoom in || Exterior - larger view|| -- Engine-zoom in -- ||Front suspension

Other stuff (partial list):
Roll cage
Trunk mods
T-56 R&R guide tube
T-56 R&R input shaft breakage
Spring cleaning
 

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Damn Coop! Looks like the only way your gonna "stop" breaking tranny's and rear end's is to set that rev limiter at 2,000 RPM :lol: Still sure you dont want to get a live axle?
Later, Andre
 

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Discussion Starter #8
Hey Andre, yeah, I agree . . . a live axle is in my future. I'm going to skip the 8.8 and go straight for a custom 9 inch. Removable 3rd member is more appealing, particularly when it comes time to do gear swaps.

Anyone have a 9 inch (or know of one) that is for sale?

Ares, the bearing caps are aluminum. Technically, bearing caps are specific to the pumpkin for which they are made. However, after blowing apart my diff last year, I now have two driver side caps. If this one goes before I get the solid axle, I'll probably just say what-the-hell and recycle one of the pumpkins and use the two caps. Everything in there (#3) is now used, including bearings, gears, adjustable shims from #2, etc, so why not recycle the caps as well?! If it is going to eventually break, I'd rather it do it with cheap (and sometimes free) good used parts.

LOL, Roadsnake (if they made a gauge that could monitor it, I'd probably have it :D).

Boss 330, that's an interesting observation, because the spider gear shaft is bent and broken, as well as the long bolt that holds it in. Looks like it may have split in that location.

I'm just trying to figure out if it is excessive flex in the pumpkin mounts, or if the cast iron carrier housing is simply too weak. Like Ralph said, it definitely is too much power for the setup. If the carrier is weak, I'll have to soon shop for something stronger that is still streetable.

Any replacement differential suggestions?

In the meantime, I've still got one spare traction-lok and a perfectly good pumpkin on the shelf, as a spare, as well as a clutch rebuild kit. Just being prepared.
 

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Coop said:
This time I figured what-the-hell, found some used 4.56's and slapped them in. I must say, it is quite a fun ride around town now! Just wish I had a 0.5 6th gear. Hmm, might have to take a deeper look into swaping out the 5th/6th gear counter shaft and getting a higher 6th gear so I can keep these 4.56's in there :D
Coop, would you like the 4.56/T-56 combo from a drag racing perspective? I've also thought the ideal gear for that tranny and around 575 RWHP is 4.30. Can you elaborate a little on your experience w/ the 4.56's? Thanks!
 

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I think the diff cratered, then that took out the cap. I don't think the rear mount had anything to do with it. Guys shatter the Traction Loks all the time in the live axles. In the live axle setup, I use a 31 spline C-Locker and a steel cap on the left side to keep that from happening. If you want to build up another one, I have a used 28 spline Locker and you can get a steel cap from Superior if it will fit, and I think it will. But you don't really need the steel cap, since it is a live axle and you can't shock it enough, LOL.

You are going to love the live axle. 1.6x 60' anywhere and 6500 rpm launches. That 9" is heavy, but good. This is fun.

Joe
 

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I just looked at the picture again, and you broke the right side cap. That one never breaks first. The diff broke and took out the cap. The left cap is the one that will break. Mine won't, LOL.
Joe
 

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[email protected] dude you blew that thing apart. I would say that is a sign for a solid rearend. You can get pre-fabed 9"s for our cars I don't know where at for sure but there is a place taht sets them up, you can order with the axles, diff, and gear ratio you want, I think this would be the way for you to go if you are that hard on stuff:D
 

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Discussion Starter #13
Joe, I thought about using steel caps awhile back, but wasn't sure if I could mix and match them onto the aluminum pumpkin (different metals). However, this is #2 that has shattered and each time the diff grenades, my passenger side cap breaks (if that is the sequence), which cocks the half shaft at an angle, taking out the ABS sensor as well :mad:. Fortunately, last time out to the junkyard, I picked up a few sensors from a Mark VIII and they work fine :D. Saved a bundle.

Thanks for the feedback, BTW. I wasn't sure about the breakage. I thought maybe the carrier broke AFTER the bearing cap broke, and then simply got fragmented into peices by the turning ring & pinion gear. So if it is the carrier that is weak, I'm going to have to look for a suitable replacement. Fortunately I still have another traction-lok laying around in case this one breaks, since I've got to save my pennies for awhile before I can even think about getting that 9 inch rear. Money is real tight these days, so it'll have to be junkyard parts and freebies for now, LOL.

How is that 28 spline Locker for around town use and how will it behave in higher speed cornering? Sounds kind of interesting.

yugnat'00GT, the jury is still out on the 4.56/T-56 combo in my setup. I haven't taken it out yet and really tried to do a little light-to-light F-body launch in 1st gear yet (if you know what I mean :D). I did romp on the gas pedal in first and it immediatly turned the tires loose. I've got a feeling I'll have zero traction in 1st and 2nd, but 3, 4, 5 and 6 pull real hard now. I'm thinking 4.10's or 4.30's for the Ford T-56 and 4.56 for the Viper spec T-56 (because of the higher gears) would be the ideal combo. I'm not about to do a Viper spec at this point, but if the 5th/6th can be modified (depending on parts availability), I may try it and just have to learn to keep my foot out of it in 1st and 2nd.

98N2OGT, I figure I'll have awhile to look for the 9 inch setup, since window shopping is all I can do for now :eek:.
 

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Coop--I have some spare Traction-Loks if you run out, which you will. I will loan you the C-Locker if you get desperate. I also have a pumpkin case and several halfshafts. E-mail me if you get in a bind.
Joe
 
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