MG Sports Cars

I am thinking of using a Jag rear end in my MGA V8 project. I know it is heavier, but seems to have some advantages, i.e. IRS, simple installation, easy to narrow, Posi and decent gear ratios available. (Actually I have my eye on an E-type rear end which is only 1-1/2" wider that the stock MG rear end, 3.54:1 gears and Posi.) Does anyone have experience, positive or negative using the Jag unit under an MGB?
Thanks!!

Tom Hoagland in Adrian, Michigan has done at least one of these applications, possibly more. I know his current project has that setup. Unfortunately, Tom is currently working in Panama and will not be back until the middle of March. Kurt, when he gets back, I'll have him contact you.
Mike Maloney

Kurt,

Evan Amaya has one in his B: [www.britishv8.org]

Roger Williams has info on this in his "How To Give Your MGB V8 Power" book, third edition.

Street Rod magazine had a series of article on the Jag IRS a few years ago.

Kurt, no doubt you've seen that we're doing a Jag IRS for the Roadmaster, and that there's also been a lot of IRS investigation on the 340 thread. Of course we don't have any driving results yet, but we do have feedback from Kevin who does have experience with them. Perhaps you should contact Kevin.
[forum.britishv8.org]


Jim

Let's not forget Nick Smallwood over in the UK.

[www.mgbv8.co.uk]


I always thought the early Jag IRS was a good choice if available at a good price. With the correct offset wheels, no narrowing would be needed.

Hi Guys,
Thanks for all the info and comments!!! I am definitely going with the Jag rear end, just have to find the proper one now. After all the reading the last week, I am surprised that these units are not used more often. Easily narrowed, installed and Summit only wants $169 for Dana 44 gears. The E-type rear end I was looking at is on E-bay for about $500. Unfortunately it has wire wheel hubs. did read in Roger Williams book that these go for about $2000 in the UK. It is tempting to buy it and put it on E-Bay.uk! I was also wondering if the Jag wire wheels would hold up to a Ford 302? Wires would really look nice on the MGA but I am sure I would be going way past my budget.
Mike, I did try and get hold of Tom a couple of weeks ago and got his answering phone message about his 2/22 return. I will call him then. I had guessed he was in China again.
Thanks again!

Kurt,

Did you get the package I sent you? It was a large file, so your ISP may not have let it go through. If not, let me know and I'll make copies and snail-mail to you.

Have you checked these folks out? [www.cwiinc.com]

Dan

Dan,
Yes I did receive the file, just having trouble opening it. I will persist!! (Thank you for sending it!) I did visit CW's website. Nice rear ends, I am trying to steal as many ideas from them and accomplishing them with junkyard/swapmeet/fabricated parts. I am really kicking myself, I passed up on two Jag rear ends at swap meets last year, both for less than $200.

Kurt,

Just in case you miss it I posted some additional info on the UK BBS.

Kevin

There are a number of Jag rears which all look sort of alike. Some have Posi (E type and some XJS's) and some don't (XJ6 mostly don't). I believe there are a number of widths are available.

Thanks again for all the info guys! I did get the info on the BBS Kevin, thanks!! There are a couple of Jag rear ends on local craigs lists, I just have to get the sellers to reply. The swap meet season starts here is a couple of months, so I am sure between craigs' list, swap meets and boneyard searches a good rear end, at a good price, should show up. I certainly have plenty of other work on the MGA to keep me busy.

Kurt, if you can pick up an XJ6 unit cheap, then a Dana 44 posi and choice of gears is not all that hard to come by so I wouldn't get too concerned about having to have a posi and the right gears. But, dana's used two different posi cases depending on the ratio. Best I remember the split was at about the 3.76 ratio so if you find one for a 3.54 it should handle all of the lower gearsets but if it's a 4.10 you might not want it. The lower one can be used with the higher gears but need a spacer. Going the other way you have to get the other case. There just isn't room to get the pinion in there. (The spacer works but...)

I wouldn't get too wound up in looking for an XKE unit either. Shortening the LCA's and half-shafts is by now a well established art and anything from shade tree to high tech can be done reliably. Stay tuned to the Roadmaster and 340 threads, we should have a Jag IRS installed by late spring.

Jim

Did anyone read Jim's vibration encounter while machining the Jag half-shafts for the Roadmaster project?

My Jag rear end is fullly assembled and not once did I consider having teh half-shafts & u-joints balanced. Has anyone had their half-shafts with u-joints balanced as a unit? What about brake rotors?

Would appreciate the pro and cons.

Thanks,

Arthur

Arthur,
I have given the same issue some thoughts and have seen no mention in the Jag rear end modifications literature I have read so far. Based on past experience with driveshafts, I would think that the half-shafts should definitely be balanced. This is inexpensive and would prevent getting the car on the road and having a nagging vibration in the rear. If the shafts are not more than a few thousands out of straight, the joints are perfectly lined up, and the splice weld is of consistant width/height around the entire circumference you can probably get away with it, but for $100 or less I wouldn't risk it. Since your rear end is assembled, I would check the joint allignment and weld beads. If they look good, put a dial indicator on the center of the shafts and check the run-out. I would imagine that somewhere in Jag books or the internet, are tolerances to check against.

Kurt,

My Jag rear is off an XKE and the halfshafts are OEM and have not been modified/shortened. However, when I rebuilt them, I may not have aligned the u-joints in the original configuration, could they now be out of balance because of this mis-step. I have not heard or read about any issues with Jaguars having vibration problems. I can only guess that Jaguar was doing the original balancing well?

Now if my shafts were bent, I could have a problem. Also, as my rear end is solid mounted to the frame, any out of balance may be magnified by the chassis and body. I could be unlucky, the out of balance if any, could perfectly match the resonance frequency of the body/frame and that could vibrate all my body joints and teeth into a loose pile. LOL, Imigination going wild here.

Appreciate your response.

Arthur

Problem with that approach Kurt is that the half shafts are not even remotely close to round in cross section. There is probably no less than .100" of runout as forged. So dialing it in isn't really a good option. They can be balanced but they can't really be trued with any accuracy. Using the turn-and-tube method to shorten, this becomes feasible, but I think Arthur's car uses the XKE parts in stock length.

Jim

Here is a link to a very detailed description of Jaguar rear ends and how to modify them [home.bresnan.net]

The specific information is for a Mustang conversion, but 95% of it applies to an MG conversion.

Thanks for posting that link, it stirred me to action. Current prices from David are as follows:

"69-73 XJ6 - 3:54, non locking ($350, have 1)
73-79 XJ12 , 3:31 locking ( $400, may have 1)
74-78 XJ6 , 3:31 non locking (Don't have any)
79 - 87 XJ12 - Only sold outside of US
79-81 XJ6 - 3:07 non locking ($300, may have 1)
82-87 XJ6 - 2:88 non locking ($300, have several)
All XJS - 2:88 locking (don't have any)

Those are for US version cars. There are some exceptions. The Euro XJ6 Series 3 (82-87) came with a locking 3:08."

I just bought a Jag IRS posi from a different source for $250, that looks to be a right good bargain, especially if the brakes are good. You may be able to find a better deal at the swap meets this summer or on ebay or Craigslist, and if I see one I'll pass it along. But I'm about done with shopping for awhile. David's prices really aren't bad at all, and if NC is within range....

Jim

Wow. Lot's of great info in that link, Larry!

If anyone wants a Jag rear end and is near a Pull-A-Part junkyard (www.pullapart) keep an eye on thier inventory.Awesome yard, very clean customer area and neatly arranged inventory plus thier inventory and standardized prices are on the net. They willl even E-mail you if they get in a car you are looking for. You pull the parts but they have forklift service to help with the heavy stuff. With the considerable help of a strong nephew, I got a 3.31:1, power-lok Jag rear end this morning for $82.60 complete. This was out of a '76 XJ12. They charged a $13 more for the driveshaft. THe first time to take out a Jag rear end took about 4 hours, could do it in 1/3 the time If had to do it again. (Take a battery powered hacksaw for the dual exhaust which is threaded through the rear end housing, lots of fun to chisel through without the hacksaw!)
Sure can't beat that price!!