Thread: wheel offsets- jag irs

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hi everyone
has anyone here-or anyone know of any- 41-48 fords with 72 jag (xjs?) rear ends?
its wider than the type most rodders use but ive been told but a good source that it can and has been done but the wheel offset needs to be right so i would like to know if anyone has done it before.

Originally Posted by spikeo

hi everyone
has anyone here-or anyone know of any- 41-48 fords with 72 jag (xjs?) rear ends?
its wider than the type most rodders use but ive been told but a good source that it can and has been done but the wheel offset needs to be right so i would like to know if anyone has done it before.

Hey Spikeo, Welcome!!

I just read somewhere that the Jag IRS is around 61" wide from each wheel mounting surface. I know the 41-48 Fords are wider than the 35-40 Fords but I don't remember how much. I have a '58 Ford 9" rear in my 37 Ford sedan that is 57.25". Given the difference in width between the two cars (37 & 48 Fords), I don't think the Jag rearend will give you much of a problem with wheel offset.

Are you going to use the Jag IFS on the front, too? I read a few posts on another forum where they were using both the IFS & IRS in 48 Ford pickups. I think the car & truck frames are different by then but in either case, they said for the Jag suspension to give proper handling & ride, the frame itself must be very stiff & rigid. If that's true, you'll probably need to box the entire 48 chassis and maybe stiffen the X-member some.

I hope somebody comes along soon who has some actual experience with this swap but there's a little bit to chew on for now. Keep us posted. sounds like a fun project!

Randy

Here's a little more info for you: http://www.snowwhiteltd.com/inst_40fordcross.htm

The XKE is narrower but has spline drive for wire wheels ..parts will interchange to use the XJS hubs that uses 4.75 chevy pattern wheels. ,, I have seen a few write ups of how to narrow the sedan stuff, I bought 3 jag rears for $500 at a bone yard in Calif, 2 later model fronts for $250 ...K & K crosmembers in New ZEland. has a custom crosmember for front stuff. I plan on making my own front crossmember and using chevy mid sized cavilar center pivot rear racks. jag swaps are popular in england into us cars-trucks google jag ifs, irs etc and you should be able to find a lot of Info. My son put one of the rears in his 22 dodge lakester, we used an old set of CCR T bucket plans to make the rear brackets with an optical tracer plasma cutter that looked at the ccr prints. . after cutting out 3 sets we found the prints were not right, probably some distortion in the printing process, best to draft your own paterns checking all the dimensions and cutting up a jag cage and using transfer punches to get an exact hope placement.

Originally Posted by randyr

Hey Spikeo, Welcome!!

I just read somewhere that the Jag IRS is around 61" wide from each wheel mounting surface. I know the 41-48 Fords are wider than the 35-40 Fords but I don't remember how much. I have a '58 Ford 9" rear in my 37 Ford sedan that is 57.25". Given the difference in width between the two cars (37 & 48 Fords), I don't think the Jag rearend will give you much of a problem with wheel offset.

Are you going to use the Jag IFS on the front, too? I read a few posts on another forum where they were using both the IFS & IRS in 48 Ford pickups. I think the car & truck frames are different by then but in either case, they said for the Jag suspension to give proper handling & ride, the frame itself must be very stiff & rigid. If that's true, you'll probably need to box the entire 48 chassis and maybe stiffen the X-member some.

I hope somebody comes along soon who has some actual experience with this swap but there's a little bit to chew on for now. Keep us posted. sounds like a fun project!

Randy

yeah thanks for the reply. ill be using the front out of the same jag got virtually complete donor car minus engin/trans which i dont need anyway.

my boss who ive bought them both from has been a rodder for a long time! the 48 has been unfinished for 20 years! he knows of a guy over here who has a 40 coupe with the same rear in it- so he called him at 20 past 6 one morning to ask him! and he said they can be used but thew wheel offset will be different to the narrower jag rears which are used in the earlier model rods.

on the front he said i should be able to fit 5- 5 1/'2'' rims and not have problems hitting the guards lock to lock, i could narrow the crossmember easily enough but since im on a fairly tight budget narrowing the steering rack is not really an option but with the narrow front wheels it will be alright anyway.

im also hoping to put it on 'bags as well later on as they can bolt straight on replacing the coil overs. so im hoping to set it up to sit in the weeds.

as for building the chassis (or frame as you guys say) ill be making a full chassis jig and our laws over here are very strict compared to yours in the states but i prefere to over engineer anyway.

i spose ill find out when i get the jag apart and measure up!

I have a 73 Mustang 9" under my 46 Ford Bus cpe. It is 61.25" inches flange to flange. I have 8" wheels with 4.5" backspacing and 225-70x15 tires. There is plenty of clearance both to body and fenders. In fact, another 1/2" toward outside would fill the opening best.

Originally Posted by slowpoke

I have a 73 Mustang 9" under my 46 Ford Bus cpe. It is 61.25" inches flange to flange. I have 8" wheels with 4.5" backspacing and 225-70x15 tires. There is plenty of clearance both to body and fenders. In fact, another 1/2" toward outside would fill the opening best.

thats good to know. i think i read somewhere that the later jags, inc mine are 61'' so your 9 inch is bloody close to that! mines been tubbed to suit 10'' on the back so i should have plenty of clearance on the inside.