Jag Rear End-Width

[Route 66]

Hi Folks, We, my sons & I are new to the Forum and to building an AC Cobra. We have chosen a DRB Boss Cobra to have Jag Suspension, Boss 260/290 & 6spd Manual most likely from a donor car if we can find the right one. We plan do everything we can ourselves perhaps foolishly but with passion. We have lots of questions but have 3 to start and a general request so I'll split them up and look forward your suggestions.

1st Question

The Jag Rear End is a quandary in that it seems most owners shorten the XJ6/12 Arms and Axles (by 65mm per side) to get a desired offset and dish on the wheels. We have seen various threads that suggest that an E-Type Series III is narrower (by 101mm overall track) and would not need mods but are rare and hard to find. I wonder whether the age is also an issue and also whether there are other issues like mounting bolt patterns that could cause problems? Any advice would be greatly appreciated on the query and/or where to get one. We have spoken to a couple of Brisbane wreckers and getting the right ratio with an LSD is difficult (make that impossible). We are planning on a 3:54 or perhaps a 3:31 in LSD.

Regards


Route 66
Brisbane, Qld

[Rebel1]

Route 66 ( I remember that TV show)

I find these guys good for used parts. They are in Melbourne and know their Jags.

Jaguar Spare Parts Supplier - Jagdaim - Australia's Largest Independant

What side of the river are you?.

[B.M.B.C]

Hi Route66

I have the Jag axle shafts and lower links you need . PM me

Thanks

[B.M.B.C]

Hi Route66

I have the Jag axle shafts and lower links you need . PM me

Thanks

[kyleb]

I would use the arms but don't bother with the original axles. I know a number of people who have snapped them. Use the ends and have the axle made by spicer or a tail shaft specialist to the correct length using the heavier unis and then you can forget about them.
The problem with the JAG rear is availability of new parts. I rebuilt mine with a new crownwheel and pinion from Dennis whelch motorsports in the U.K and fitted an Auburg gear LSD clutch pack. It is now pretty much indestructible but took some working out.
That's not to say you can't get a good second hand unit that will last ages, just food for thought in regards to longevity and how much power you will put through it.

[kyleb]

By the way it is very important to get the right housing for the LSD, also with regards to the housing, some are machined flat and others depending on mark machined at an angle so that the pinion pointed slightly up. Make sure you get the one suitable to your chassis mounting position. Hope that helps....

[Rebel1]

With regard to servicing the Jag center you should be aware of this info:
DazeCars, Mustang IRS or Independent Rear Suspension page IV

With regard to shortening and other info then go here:
Independent Rear Suspension Forum / The Jaguar IRS picture thread

and here:
DazeCars, Mustang IRS or Independent Rear Suspension page III

With regard to other info re IRS then choose a thread from here:
Independent Rear Suspension Forum / Independent Rear Suspension Forum

[Route 66]

Originally Posted by Rebel1

Route 66 ( I remember that TV show)

I find these guys good for used parts. They are in Melbourne and know their Jags.

Jaguar Spare Parts Supplier - Jagdaim - Australia's Largest Independant

What side of the river are you?.

Hi Rebel1,

I am a Northside boy!!! I remember the TV show too which kind of shows my age, I even watched a rerun the other night. When Peter R. told me his next Chassis no for the Boss Cobra was #66 I figured it as an omen and finally placed an order after pondering for a long time.

I have spoken to the guy from Jagdaim and he was very helpful. He has a XJ series with an LSD but not in 3:54, but does have a set of 3:54 gears. Add freight, shortening and setting up the diff with changed gears and bang goes the bucks. While I am a bit concerned about the age of an E-Type it seems not having to shorten the arms etc is a plus. If I can find one? I do have some leads however!!!

Regards



Route 66

[Rebel1]

Originally Posted by Route 66

Hi Rebel1,

I am a Northside boy!!! Route 66

Ahhh ... a northside fella. If you were from that other side I'd delete my posts. Way too many of those southsiders on here.

[Route 66]

Originally Posted by Rebel1

With regard to servicing the Jag center you should be aware of this info:
DazeCars, Mustang IRS or Independent Rear Suspension page IV

With regard to shortening and other info then go here:
Independent Rear Suspension Forum / The Jaguar IRS picture thread

and here:
DazeCars, Mustang IRS or Independent Rear Suspension page III

With regard to other info re IRS then choose a thread from here:
Independent Rear Suspension Forum / Independent Rear Suspension Forum

Thanks again Rebel1 for the links... there is food for thought there! One of things I was actually keen to do was source the front and rear ends and recon them myself. (Excluding shortening).

Regards

Route 66

[Rebel1]

Originally Posted by Route 66

Thanks again Rebel1 for the links... there is food for thought there! One of things I was actually keen to do was source the front and rear ends and recon them myself. (Excluding shortening).

Regards

Route 66

For what it's worth Diff Lapping at Kedron have an almost standard charge for reconditioning Jag Diffs .... $1000.00 inc parts.

The front end is easy with new bits from JagDaim. So are all the bits outside of the diff Center. Hub, inner pivots etc. Shortening by any driveshaft shop or Hardy Spicer atr Eagle Farm.

Whilst it's all apart, paint with POR15 and It'll all look new.

[Rebel1]

OOpsy, forgot to mention:

Jagdaim also sell a VENTED rear disk rotor kit for the Jag. The standard solid rotors have a habit of cooking your drive shaft seals if you get them too hot.

They also sell a kit using the later series hubs etc, to convert to outboard disks keeping the early series lower arms, driveshafts and center etc.

[Route 66]

Hi Kyle,

Thanks for the responses. I am concerned about the strength of shortened components and it is a priority. Some recent posts I have read are a bit scary. Some blogs make out the Jag gear to be like a truck and it seems widely used by hotrodders etc but finding some experienced can be difficult. There seems to be some leads on brand new parts from the states in some blogs I will check out. If I can find a diff centre in 3:54 with an LSD my brains trust at work are confident they can rebuild it without having to go a Diff specialist which would use up some cash.

Thanks


Route 66

Originally Posted by kyleb

I would use the arms but don't bother with the original axles. I know a number of people who have snapped them. Use the ends and have the axle made by spicer or a tail shaft specialist to the correct length using the heavier unis and then you can forget about them.
The problem with the JAG rear is availability of new parts. I rebuilt mine with a new crownwheel and pinion from Dennis whelch motorsports in the U.K and fitted an Auburg gear LSD clutch pack. It is now pretty much indestructible but took some working out.
That's not to say you can't get a good second hand unit that will last ages, just food for thought in regards to longevity and how much power you will put through it.

[Route 66]

Hi again folks,

Since posting the orginal query I have received some good advice to my various questions (thanks!!!) and also done some more research. I have not been able to track down a XJ6/12 III rear here in Brisvegas with the desired ratio (3:54) and/or LSD. Seems I can get it in bits down south in Melb but then would most likely need a visit to a diff specialist $$$ to swap gears etc plus freight blah blah. Then I ran into the headache that I could not find anyone up in my local area to shorten the Lower Control Arms? Draiveshafts are no problem - curious? The Qld Cobra Club connections have come through with a recommendation on the shortening issue. From posts I have read about LCA failures and one in particular which lead to a crash I am concerned about the strength and safety issues.

I have received a lead from OS about a set of E-Type Shafts and Control arms plus also a XJS diff centre with 3:54/LSD. I am not sure if this all can be mixed and matched? A local wrecker is adamant that the XJS Diff centre will be interchangable with XJ6/12? Peter R did say the E-Type (S3) gear was ok especially because it was already narrower but wasn't too confident about the XJS crossover? In theory it seems ok if it all worked together? If it was local it would be a big deal but the parts are a long boat ride away. The impression I get is if you ask a local (OZ) wrecker about E-Type parts they either laugh or you here the cash register ringing in the background. It is not all about the money but every couple of $'s I save puts a beer in the fridge in the shed for those long hours.

At the end of the day the outcome I am looking for is 3:54 LSD narrowed to get required offset for a slight dish on rear with 9" to 10" X 17" 's. (and strong & safe!!!)

The theory:- Get Local XJ6 complete rear - (cheap) -for brakes, hubs loose-ends. Source E-Type Shafts & LCA's and marry up to XJS 3:54 LSD??? (No shotening & no trip to Diff shop just near seals etc.)

Does any one know the answers????

On a side note I followed-up a thread on aftermarket lower control arms from the US but the business no longer operates.

Regards



Route 66
Not so sunny Brisbane Qld

[kyleb]

Personally I would'nt worry too much about shortening the LCAs as long as you brace them. Some people have fitted the LCAs with no bracing between the pivot points and that is a concern. I think the car involved in the accident you refer to was such from memory.
The xjs centre will work, but make sure it has the later taper axle bearings. The most difficult part of rebuilding these diffs is the preload, due to the fact this is accomplished with shimming the bearings.
VA Spiteri in melbourne modified mine with the Auburn Gear centre which is working a treat, they tell me it was not straight forward but they now have the knowhow and measurements required to do it. Although not cheap they do good work.
The problem we have is the 19 spline axles which is a little odd.
The complete Auburn LSD centre was cheap, about $500 from memory.
The REAL danger I believe is the driveshafts. All the weight of that corner is pushing towards the diff centre, so the possibility exists that if you break one the wheel can end up in the top of the wheel arch.

Note the adjustable bracing which is on both sides of the LCA.
Hope this helps a little
Kyle..

[Rebel1]

Route 66, Did you try Hardy Spicer at Eagle Farm for the shortening of the drive shafts?.

Mine were shortened by the Kit supplier in WA and the tubing used is 75mm OD.

Have you spoken to Scott Hampson regarding the shortening of lower control arms?. He may know where you can get them shortened. He has worked on many many cobras with Jag suspension.

His site: Welcome to Venom Custom Fabrications

Remember any mods to suspension bits need your engineers approval.

[Route 66]

Hi Rebel1,

I did contact Hardy Spicers and they are happy the shorten the Axles/Driveshafts but wont touch the Control Arms. The other Drivesaft shops in Brisvegas were either the same or not sure. Through the Qld Cobra Club I have made contact with Scott as you mentioned and he is sidetracked at the moment but says he will be able to look at for me in a the not too distant future which sounds ok.

The whole shortening scenario seems a bit of a negative for both compliance, cost and reliablility hence my query about being able to mix E-Type bits. To a degree I would however think that a well engineered job would be as strong if not stronger?

Thanks again for the feedback - I am learning fast and enjoying the challenge.

Regards


Route 66

Originally Posted by Rebel1

Route 66, Did you try Hardy Spicer at Eagle Farm for the shortening of the drive shafts?.

Mine were shortened by the Kit supplier in WA and the tubing used is 75mm OD.

Have you spoken to Scott Hampson regarding the shortening of lower control arms?. He may know where you can get them shortened. He has worked on many many cobras with Jag suspension.

His site: Welcome to Venom Custom Fabrications

Remember any mods to suspension bits need your engineers approval.

[Rebel1]

Originally Posted by Route 66

The whole shortening scenario seems a bit of a negative for both compliance, cost and reliablility hence my query about being able to mix E-Type bits.

There are a lot of Cobras running around in Bris with shortened lower arms.

I've yet to hear of one having problems.

I'm surprised Peter R didn't refer you to somebody to shorten them.

[Chris L]

G;day Routte 66;
My 2 cents worth.........

If the job on the control arms is done properly, you wont have a problem with strength. Be sure who ever does them uses a jig, one of mine was out 4mm and made getting everything pointing in the right direction impossible without shortening wheelbase on one side of the car !!.
As for the diff, I sold a 3;54 lsd centre about a year ago and replaced it with a detroit soft lock centre ( to suit Dana 44 from memory) that was second hand (done 30klms) from an American friend I contacted through these forums. He let me have it for $300 which I thought was excellent.Have a good look at your drive shaft splines for wear. New bearings and seals thoughout, and some very skilled help from some mates at Ford performance Racing saw it all go together nicely. Could not be happier with the result. I would also strongly advise to go with outboard rear brakes if you can, set a mechanical handbrake assembly and ditch the complete inboard rear calipers and rotors.

I dont ever want to have the diff out of the car again, its a Python Kit and its not much fun getting access to some areas, but I imagine that may be a common deal.

Cheers
Chris

[Route 66]

Hi Guys,

As an update to my Jag Rear end query, from the start Peter (DRB) told me if I could find an E-Type rear it would solve my width and narrowing issues. He said they were rare and expensive but worth a try. First couple of guys laughed but I made a few enquiries around various sources and Gary from JagAyre Melbourne found me a Series II E-Type 3:31 Posi complete rear in pretty good nick. Price was cool, only $200 more then one local guy had quoted for an XJ6 LSD rear +$200 frieight. It has just arrived from Vic and is as described, has the larger later style brakes which are in better condition then the brakes on the Series III XJ6 front end I have. Diff has a little backlash but virtually no oil leaks? Surprising from what I've seen of any Jag rear ends. While I was looking for a 3:54 this is a reasonable comprise but the main bonus is no narrowing required. That had been a headache just finding someone to do it in Qld (Cobra Club did come thru there though) and also burns quite a few dollars. The hub to hub width issue still has me puzzled I must admit. This rear is just under 54 & 1/2" hub to hub unloaded and I would guess at normal ride height would add just under an inch to be about 55 & 1/2", this is pretty close to the 56" I've been told I needed to cut the XJ6 down to. unfortunately the various Jag forums only talk track and not hub to hub specs but it matters little now I guess as I have it here sitting on the bench.

Hopefully the diff won't need a complete rebuild but we shall see. Very likely there would be a roll of the dice with any XJ6 I would have found. It a little older but aren't we all.

Regards


Route 66

Ps: Hopefully striping it down won't be as big a pain as the front end. I still have sore knuckles from the springs and ball joints.

I must admit I can't wait to get the car sitting on wheels, that we be a hug milestone!!!!