Jaguar Xj6 front subframe swap on 52' 3100 help
 

Hey fellas i will soon be removing my front suspension on my 1952 3100 and i would like some tips on welding in a jaguar xj6 front subframe.. I have a complete car 1986 xj6 available so its only right I do this mod... I would also like my truck to ride low.. I have read somewhere that some folks knotch the subframe itself right where the truck frame rails meet the subframe and tuck in the truck frame into the jag subframe.. im open to any and all suggestions and tips.. Thanks to everyone in advance

Re: Jaguar Xj6 front subframe swap on 52' 3100 help
 

The whole assembly unbolts from the Jag with just a few bolts but has a lot of brackets that have to be cut off. This is the one that belongs to a member on here.
https://hosting.photobucket.com/c5e8...720&fit=bounds

This is one I found on the net. It may or may not belong to a member.

https://hosting.photobucket.com/c5e8...720&fit=bounds

Another net find with a GMC frame.

https://hosting.photobucket.com/c5e8...720&fit=bounds

The one I have that I bought in Bend Oregon a few years ago compared to a chevy truck front axle.
https://hosting.photobucket.com/c5e8...720&fit=bounds


A closer idea of mine giving you and idea of where you might notch it.
https://hosting.photobucket.com/c5e8...720&fit=bounds

If the Jag is still complete with engine and trans get it on a flat surface and get under the front and measure from the bottom of the crossmember to the floor. When I started figuring out how I was going to set the chassis up so it was at the ride height I want I would block it up that distance off the garage floor and set the front of the frame on it to see how high the running boards are.

A Jag weighs 4000 lbs if you average out several different weights. I can't find a weight bias but the six weighs about 750 lbs. Less weight means that the rig will sit higher with the same springs though.

Re: Jaguar Xj6 front subframe swap on 52' 3100 help
 

if you can pin the suspension at ride height with the weight of the vehicle and engine etc still on it, before you remove the front end, then you will have the suspension sitting where it is supposed to be for the proper geometry. then, when it's out of the car, do as mr48 says and place that on a set of blocks so you can put the truck on top of it to check your actual ride height. if you have a set of wheels for it, with the wheels/tires you want to use or at least with tires of the correct diameter/height you wanna end up with, then that will give you a great idea of how tall your truck will be with the suspension where it needs to be for the stock geometry. you can then decide if you need to notch the frame or not. when you get done, if you find the stock jag spring set up is too strong or not strong enough, you can adjust/swap the springs to match it back up to the stock jag ride height where your previous suspension pins were. i have simply used some square tubing as pins to pin suspension before, drilled and placed where the shocks would normally be sitting. jag may not have that kinda configuration but you can figure something out that will do the same thing.

Re: Jaguar Xj6 front subframe swap on 52' 3100 help
 

Thanks a bunch for all the good info "Mr48chevy" and "dsraven" for all the great info especially all the great pictures Mr48chevy! I will definitely be using all you guy's information 🤠👍🏻

Re: Jaguar Xj6 front subframe swap on 52' 3100 help
 

not familiar with the jag front end when in the car. does it have struts or regular coil springs and separate shocks?
not that it really matters but if it has a separate shock then it can be removed and a solid link can be placed in it's spot to pin the suspension at that particular ride height. it is helpful to do this first on the donor while the engine, trans, etc are all still in the vehicle because the suspension is basically in the middle of it's travel there. so, you want the same as that when it's under your truck. it's always best to keep things in the zone they were engineered to work best. if it has struts that bolt onto the body at the top instead of being an assembled part of the suspension when it is removed, then build some sort of a link that will bolt onto the suspension parts to keep the control arms locked at the stock ride height. something that will come out of of the car with the suspension. a bolt on link can be removed for doing work, but installed whenever you need so that you can re-create the stock ride height
hopefully that made sense

Re: Jaguar Xj6 front subframe swap on 52' 3100 help
 

another good thing to do before removing the donor's suspension is to place the donor car on a flat level surface, air up all the tires to factory spec and ensure they are the correct sizes, remove stuff in the trunk or interior that wasn't there when the car was new, then take an angle measurement on the lower control arm, fore to aft, so you know what angle it is supposed to be at when installed in your truck. duplicate that angle with your truck at the rake angle you want and the tire diameters you want. I use a digital torpedo level for this, they are fairly cheap, as far as tools and truck parts go, and you will likely need one when doing the suspension install anyway. they can be placed on a 4ft level (which is used as the straight edge to support the short level) to set your truck frame up level side to side and at the rake angle you desire.

Re: Jaguar Xj6 front subframe swap on 52' 3100 help
 

here is a site that can also help you with tire size changes and how they may affect steering due to scrub radius angle changes. it has to do with king pin inclination, or steering axis inclination, which will affect how much the steering is affected when tires encounter a crack in the road or grooved out lanes etc. also how the vehicle will steer around a corner, as in, how the tire offset tends to give a lot of feedback through the wheel that you need to hold back.
just a heads up on whether you want to change from the original tire diameter and wheel offsets that the jag was set up for

Re: Jaguar Xj6 front subframe swap on 52' 3100 help
 

Re: Jaguar Xj6 front subframe swap on 52' 3100 help
 

That is some good advice. Block the crossmember up so it is sitting just like it did in the donor and then fit the frame up to it on the same plane that the donor car body was on.

When we put the Nova subframe under my 51 Merc we got one of my students Nova in the shop and took some measurements off it.

Re: Jaguar Xj6 front subframe swap on 52' 3100 help
 

Does anyone have a picture of a 3100 with the xj6 subframe installed that shows the actual ride height? With and without mods if possible.. thanks

Re: Jaguar Xj6 front subframe swap on 52' 3100 help
 

My '49 GMC has a Jaguar suspension from a Series 3 XJ6. Here's the truck at its normal ride height.

http://67-72chevytrucks.com/gallery/...Show_Low_2.jpg

This Jag subframe is soft-mounted with no modifications to the truck frame or the crossmember. It is on airbags, but the ride-height is set to what it would be for an XJ6 (corrected for different tire diameter than the Jag) The XJ6 S3 ride height specification is usually expressed as a distance from the bottom of the crossmember to the ground, and if I recall correctly is about 4.5" for my truck.

At the correct ride height (the XJ6's ride height), the distance from the bottom of the running boards to the ground is about a beer can's height.

I fabbed the brackets for the crossmember to bolt it to the truck by setting the caster adjustment on the Jag's upper a-arm to the nominal position (no shims) and then set the caster at 5 degrees and made the brackets to hold it there.

There's a build thread for this truck that includes the Jag suspension installation at https://67-72chevytrucks.com/vboard/...d.php?t=725080

Re: Jaguar Xj6 front subframe swap on 52' 3100 help
 

e, that ride height is perfect. I'm betting it rides well and travels over speed bumps pretty well too, without taking paint off the underside or creating havoc in the line up of cars behind you.

Re: Jaguar Xj6 front subframe swap on 52' 3100 help
 

Thanks. I've owned both a Jaguar XJ6 and an XJS with this suspension and thought the ride quality for both was exceptional and wanted to have my truck ride be similar.

Unfortunetly, I installed air bags in the truck, and while it rides OK, it is a bit harsher than I'd experienced in my Jags.

The airbag's effective spring rate isn't linear - it increases pretty rapidly due to its small volume of the airbag that will fit where the Jag's spring was installed, and this makes it stiff over bigger bumps. The truck has a 40 series tire (the Jag had a 70 series tire) and the increased sidewall stiffness contributes to the harsh ride too. I've got a set of factory coil springs sitting on the bench waiting to be installed in my truck.

https://talk.classicparts.com/media/...l?d=1587951677

OP - here's a few other things to consider

-The Jag is 'rear steer' unlike a Mustang 2 IFS which is 'front steer'. This puts the rack tower underneath the engine's headers. It can be difficult to find an exhaust manifold/header that will work

-The bushings in the Jag subframe that hold the steering rack are garbage - you'll need to find/make some urethane bushings

-The upper shock mount on the Jag are part of the body so you'll have to weld a shock mount to the subframe. I got mine from 'Suicide Doors" (I think they have a different name these days - ThorBros?)

-The Jag's sway bar bracket are part of the body too, so you'll need to fabricate some brackets to mount it to your truck's chassis

-The Jag uses an Adwest steering rack with a 48-tooth input spline. You can buy a u-joint from Borgeson to get from the Jag's spline to double-D steering shaft.

-Rebuilt steering racks are hard to find and pretty spendy. I had mine rebuilt at a local rack and pinion rebuilder. In later years, Jag switched from Adwest to ZF. (I think these only came on the last XKS Jags) If you can find the German rack, it is much better and less prone to leaking.

-Most parts to rebuild the suspension are available from Moss Motors in Goleta California

-A standard Saginaw 'ham can' power steering pump that flows about 3-3.5GPM works well with the Jag rack. I changed the relief valve from 1300psi to about 1100psi to put a little more 'feel' in the steering. The hydraulic fittings on the Jag rack are SAE, not metric. (I installed adapters so I could run -6 JIC hydraulic hose on mine)

Re: Jaguar Xj6 front subframe swap on 52' 3100 help
 

Thank you a bunch for all the info in here guys! Also to user name "e015475" can u or someone else tell me if the 48tooth diameter shaft on the jag steering rack is 3/4" in diameter or? And also on the other end of the u-joint I need it to be for 3/4" double DD on the chevy side for my 52 3100 correct? Please someone help before purchase the incorrect one from Borgeson lol

Re: Jaguar Xj6 front subframe swap on 52' 3100 help
 

It is 3/4" - 48 spline.

I think I mis-spoke when I said it was a Borgeson u-joint on my truck, but Borgeson does make one. Part 014937.

Mine is a a Sweet Mfg u-joint that gets the 3/4"-48 to 3/4" DD.

I bought mine from Speedway motors.

https://www.speedwaymotors.com/Sweet...MGB,32713.html

If you like to scrounge junkyards and save a few bucks, the MG B uses the same spline