The vehicle must hook up before the power you are producing will break any thing. Wheel hop will be a problem once you have a limited slip or a lincoln locker (lincoln welding machines) type spool.. The engine you have is quite heavy and long for the chassis you have it in.With all of that torque, I am surprised your frame hasnt twisted like a cork screw! Do you know how much your rat rod weighs? How much of that is on the rear wheels?. TORQUE is what breaks differentials. It is the number one cause of failure in rear ends that have been set up correctly for their application. Typically the ring gear looses a tooth or two from a shock load then the kinetic energy remaining distroys everything else. I have seen lots of 4x4's with d44's shear off all of the bolts retaining the ring gear. Thats the least harmful way I have personally seen d44  fail  to date. Then again the d44's only use 3/8 bolts for the ring gear. Jag uses 7/16.  However if you cannot get your rear tires to hook up, all of that torque just makes smoke. I have a 408 C stroker with c3 heads in a 67 mustang that is easly above 550hp on pump gas. The torque figure should be in the same range. I can get it to hook up with half throttle in first and wfo in second with ideal conditions.  I have yet to break anything but frame mounts. That failure was the result of wheel hop.. If you devolop wheel hop all bets are off. The results of wheel hop with high torque applications are well documented. Something always seems to  break. When I first installed my xj6 rear in my mustang I welded up the side and spider gears because with the torque I had on tap the open differential traction was a joke. I couldnt get it to hook at all. I had a limited slip, ring and pinion, seals and bearing kit coming from E-bay so I really didnt care about the jag guts. Weather or not you break anything with a spool is directly perportional to rear tire traction. The more weight, the larger od of the tire and the stickier the tires the greater the likely hood broken parts will result. I have made lots of Lincoln lockers for 9in rears as well as Subaru rear diff's for rally events. I never had a failure. I own a toyota Tacoma that sheared its pinion supporting the spiders in the middle of no where on Mt Hood. A friend had an alternator powered buzz box and thats what I used to weld up my side gears to the carrier. I filtered the gear oil through a tee shirt and re used it. The spiders were pulverized. I drove that rig for about three weeks that way with out failure. The ring gear had some chipped teeth so it did make noise.  The only reason I used it welded so long was the vehicle was my daily driver and the electric locker I ordered took that long to get here. 

Last edited by tyrellracing (12/06/2013 2:23 pm)

Unless you're hooking and getting gobs of traction, you won't break.  With a 1,200'ish pound engine in that lightweight vehicle, I don't think you'd have that much traction w/o full on drag slicks and another 500 pounds of weight right over the axle.

Since it seems you have the center open, how do the teeth look?
If you're worried about the stub axles, Mark Williams Enterprises will make you a set of 30 spline, harden chro-moly stubs.  They run about $900 - $950.  They might do 19 spline as well, I don't know.  I can post contact information if you're interested.

BTW, thanks for upsetting tree huggers in Oregon! They are way too serious.

when the stub axles have been pulled from the diff and the carier bearing caps are removed, should the center section simply pop out or do i need to pry on it a bit? i have it all ready to come apart but im having a hard time getting the guts out of the diff housing. just wondering if im missing somthing.

The way you said it swings to the right sounds normal but swinging way out isnt. Around here the roads all have a crown to them so most vehicles will drift a little to the right unless they are in the on comming lane. Did you check the rear alignment? Sounds like you have a bent lower control arm throwing off your toe or unequal camber thrust from side to side.Or the rear suspension was put in crooked.   I would start by checking the alignment and see what you find

Last edited by tyrellracing (12/06/2013 11:04 pm)

the rear could probly use some shimming. ill take a look at that when i put it all back together.

I am sure some one here should know about the availabity of heavy duty stubs.. I am still using the 19spl.units. All of the older D44 diffs. used the same 19spl. axles and thats where I found my limited slip carrier. Modern D44's use a much improved design with a fine spline type axles. These are available on Jag stub axles on custom order only. I believe the spline count is 31 but I an not sure. The 19spl. side gears for limited slips are getting rare these days because they were concidered to be too weak when they were still being produced.  I too had problems getting the preloaded carrier in to the case. I just pried the stub axles out. There O rings are the only thing holding them in once the bolts are removed. The carrier requires some pry work to be removed as well. I dont even recal if the Jag case even has the holes for a case spreader. Does it? I know I didnt borrow one to put mine together so mine most likely doesnt have them. Any way cool project. Good luck. I wouldnt put a whole lot of faith in the stock Jag splines to support 1000lb/ft for very long. I am sure they would survive a pass or two down the 1/4,   but I would be tearing them out for inspection after that. Just my opinion. You are aware of how catastrophic the failure would be if a inner stub failed at speed.  Not a pretty picture!.As far as seals go, I just found a bearing and seal kit on e-bay. It came with shims too. You are right. the seals were nothing special so I am pretty sure the prices you posted have a substantial mark up. I like dealing with bearing distributors directly for seals. They tend to sell enough of them to not need to mark them up as high.

Last edited by tyrellracing (12/07/2013 3:43 pm)

haha! ya, it gets some looks! and it has scared its share of ladies on the road. and if you follow me too close your going to eat coal for dinner for a few miles.
i have considerd how bad it would be if i broke an axle or somthing at speed. before its back on the road im going to build an upper controll arm type of fail safe brace. this way if somthing breaks the wheel dosnt just flop over like a dead fish and send me to my death.
the saving grace of this rig is that it will never ever hook up, and in the 2 years since i finished the car, ive been too scared to push it past 3/4 throttle. its seen 3/4 throttle twise for about a split second each time and otherwise only ever sees half throttle once in awhile. both times over 1/2 throttle was just to see what it would do, and it has so much more to give at those speeds that i shut it down right away. last summer i left a new laborghini in the dust from a 75mph highway roll with half throttle.... so you can see im scared of pushing it harder, i have a family.

Just a curious question for you guys. With that double  frame LCA in Ralphys Cobra pics and the addition of a Watts link. Would that at least partially replace the need for a trailing arm ? Sorry for the thread hi-jack . Was just a quick thought.

Another post with pics from three different cars.

Fullchat289's ERA


DCDoug's CSX


MdMan352's Contemporary


Ralphy

Good work Ralphy. I knew they were a failure point from reading about it but the images you posted shows exactly what I was talking about with one glaring exception.  The rotory shear took place in an area that rendered its failure pretty much harmless. The bearing didnt seem to be damaged at all.. If the bearing remains intact and the carrier was an open type, it would behave like you put the transmission in neutral. With a limited slip you might have enough grip to keep moving but once you have stopped the posi will seldom have the grip to get you moving again  Most limited slips only have aprox. 100lb/ft required to break the clutches loose. They dont need much more than that because the difference in rear tire traction doesnt usually require it. Any one that has seen a "Z" spring posi and knows how minimal their preload is surly knows what I mean when I say "How could somthing that whimpy work"?  I have sheared an axle on 9" and with a over tight trac loc it wouldnt move under its own power once I came to rest . As for 2.88 gear sets they are much stronger than any ratio higher numerically. This is due to the number of teeth in contact. The higher you go numerically the lower the tooth count on the pinion. just by numbers alone you cannot have as many teeth contacting with a 7 tooth pinion as you can with a 12 tooth pinion. The changes occurr in steps, A 7 tooth pinion may be used on 4 different ratios, then an 8 tooth pinion will cover the next 4,ect. There are too many variations of tooth counts to be specific. Every different gear manufacturer has their own idea of whats best.   Bottom line when you get into the more aggressive ratios like 5.25's you will seldom have more than one or two teeth in mesh. 2.88 will have as many as 7 or 8 in mesh at any time. By tooth count alone the 2.88's come out ahead in strength however,. for practicality they come in last place no matter how strong they are. The problem with 2.88:1 gears is there are no factory installed manual transmissions with a low enough first gear ratio to work other than the T5 5 spd ford installed behind their 4 banger and its a pretty sad example of a T5.  Even automatics tend to struggle to pull that tall of a load. The 4+1 5spds w/o overdrive built by doug nash will perform fine with the 2.88 because they were designed to opperate that way.  They are now built by Richmond gear and are still available for a price.  So 303 Radar, You found the the stubs in 30 spline, Is that the factory D44 fine spline count for their axles? 30 is an uncommon spline count. 28, 31 are far more common.  Just curious.

Go back to my first post and find the original link. There's a picture post of all the parts one guy broke. Three difference types of half shafts.

Here, check post 18.
http://www.clubcobra.com/forums/all-cobra-talk/124452-custom-jag-irs-strength-pics-inside-2.html

Ralphy

Last edited by Ralphy (12/09/2013 8:39 pm)

303Radar wrote:

Ralphy wrote:

Go back to my first post and find the original link. There's a picture post of all the parts one guy broke. Three difference types of half shafts.

Here, check post 18.
http://www.clubcobra.com/forums/all-cobra-talk/124452-custom-jag-irs-strength-pics-inside-2.html

Ralphy

Wow, I guess I can see lots of breakage with 750 hp, sticky tires, and a quarter mile monster!

 
He says that's on his 500 plus HP car.

Ralphy

Last edited by Ralphy (12/11/2013 4:05 am)

well in light of all this reading and proof, its only a matter of time untill mine blows up and sends me into another car.
im going to ditch my IRS and go ford 9" im thinking. ill save the IRS thing for another car thats more tame.