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Jag rear


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A funny thing happened to me yesterday at work. We were waiting for the gate to open at the end of my shift and BSing about rods. All of a sudden a voice behind me said, "Any of you guys interested in a Jag rear end?" Without even turning around I said, "Sure! What ya got?"

To make along story short, a half hour later I'm staring at a complete unit right out of a running car 2 days ago.
How much?, says I.
$500. says the owner.
Too rich for me right now., says I.
How much ya give me?, says he.
$350., says I.
When do you want it delivered?, says he.

So about an hour ago, he shows up with it. We unloaded it. I gave him a check and he left.

Now, what am I going to do with it? God knows, I don't need another project. The Speedway body I just bought last weekend sure would look good with shakey legs out back. What do ya think guys?


What did I do with those CCR plans Vegasbruce sent..............
If you use the same rules I do,the following apply.
1. If you got it -- Use it.
2. Use it - or loss it. :lol:.

Nice score on the jag rear, by the way.
Well I don't have to make payments on it or feed it so....Guess I'l just sit on it for now.

OK Ron, where are the pics? :razz: Good deal though. :clap:
WOW! Just sit on it. You'll figure out where it should go when the time comes. Can't beat that price. That's close to free!
It ain't pretty enough for pics.................yet.

When I first started my roadster I had a jag unit.didn't want it broke down
in the middle kansas somewhere.
Sold it in a real big box with the axle stubs set for ford lugs for $600.00.
You got a deal for sure,BUT,Lots of dollars to get it looking brite and shiny
plus having axle stubs made to fit ford or chevy wheels.
It's out of a sedan and has a 4-3/4" bolt pattern already. As far as the polishing goes, I've done my own polishing for a number of years. Also know someone who has the key for the back door of a plating outfit.

Guess I'll have to drive around Kansas. To bad, I've always heard they were friendly there.

Seriously, I've considered that and more. Not real sure what I'm going to do with it yet. Maybe a rolling chassis to sell? Donno....

I had to pick up some tubing today for a customers frame so, I doubled the order. Also got some 3/8" plate for the mounts etc. and 7/8" DOM. Made the patterns from the CCR sheet while the saw was cutting.

GAB's trailing arms make more sence to me so I'll probably use that set up instead of the hair pins like the CCR plans. That's a better visual match for the 4 bar front end anyhow. I'm thinking of a quarter eliptical set up in front with friction shocks too.

I don't like the looks of the 4 shocks. I noticed some cars running one on each side. Can't tell from the picture if they are using the front or rear shock. Can anyone help me out there?

Sorry for taking so long to reply to your PM. I don't remember to check that spot very often. The post that you are looking for are here in the Suspension forum at the very bottom on the list. There are a couple of things there that might be what you are looking for. And just for good measure, here is another one:


If you need any other views or info, let me know.

Ive got one too. I've been sitting on it for like 3 years. Picked it up for $150 but I had to pull it. Finally found a use for it. Going to make some new lower arms for it and put it in a friends car.
Thanks George, that answers one question. Here's a couple more;
What size tubing did you use for the trailing arm?
Did you use a Jag insulater at the rear of it?
I would like to use 2 coil overs instead of 4. Would the one in front of the axle work by it's self?

Ron, this is in answer to your PM. I thought it would be helpful to post it here for others who may have or be thinking about a Jag.

The trailing arms are very important. They have to be mounted exactly right to keep the geometry of the Jag correct. I used rod ends from CWI (Custom car suspension parts) for the lower control arm connection and regular rod ends for the crossmember connection. You also want to use the urethane bushings to replace the very complicated bearings in both ends of the lower control arms.

I used four springs just for looks, but you can use just one spring per side. I've seen them both ways. The spring rate and spring length will establish your ride height, so you need to keep that in mind. I'm using 180# 9" springs and the ride height and ride quality are perfect for me. This took a lot of experimentation... I went through four sets of springs before finding the right combination.

I wrote a fairly detailed post about setting up the Jag for another forum. I'll try to find it and repost it here.
Thanks Lee. That's the kind of info i'm looking for. I've got the gear housing mounts worked out but I want to see how you built the trailing arms. Did you use heim ends at the crossmember?

The tubing for the trailing arm is 7/8" x .156" D.O.M. so that it can be tapped 5/8-18 for the rod ends on the front. The drawing shows using a bushing sleeve for using the original Jag bushings or the delrin replacements that some vendors sell. The last one that I installed (Lee in K.C.'s) he used the Kugel adjustable rod ends on the back. If I remember right, I had to make up some spacers to make up for the difference in width between the end fitting of the lower control arm and the tab. The tube was left straight on that application. I assume that this is what you are referring to in asking about the insulator.

As to using just one coilover per side, yes you could probably get away with it with no problem, but be aware that Jag rears are rather weight sensitive. You will need to change springs to make up for the change to the design. I don't know that you would have to double the spring rate but a significant amount would probably be required.

The amount of leverage exerted on the coilovers by the placement of the mounting point for the shocks in relation to the length of the lower control arm is quite a bit. The other thing that enters into it is the angle of the shock. The more angle in relation to the input of load results in the need for heavier springs to maintain ride height and ride stiffness.

A little bit of difference in the upper mounting width can mean more difference in ride than many people realize. That's probably why you see so many different opinions about which spring rates for Jag rears when that question is asked on one of these boards. It's kind of like the Harley coilover controversy. I measured one of the springs from a Harley and it was about 290# per inch. The generally accepted spring rate for coilovers with a straight axle rear on a bucket seems to be somewhere around 150#. I would think that there wouldn't be much "ride" when using the Harley units. But here again, there is leverage and angle in the mounting involved in the original application. Those definitely affect the choices to be made.

I've always been impressed with how English engineers do things very "properly". The Jag rear is a good example of that to me. All of the pivot points have needle bearings and seals. The use of the two shocks to balance the forces on the lower control arm. The entire assembly being isolated from the body structure and free to move but controlled with the paddle arms. But then too, they weren't designing an economy car.

Hope this helps...or at least doesn't confuse the issues too much more. :)
I have pix but for some reason I can't upload them. I've sent them to myself at work and will try to post them tomorrow. Got to spend some quality time with my 14-year-old. Talk to y'all tomorrow.
If you happen to look at my rear you may see some things that may answer some questions and if not I can shoot you some pics from mounts to axels also the speedway yoke . What size tires do you plane to run I will explane the reasion for asking after. Chevy wheels fit with the 1/2 inch stud on the hubs.
GAB...Your no confusing the issue at all, far from it. I know I'm going to have to make some compromises in mounting this and want to know the why's and what for's.

If this comes to pass, I'm looking at a 300 H.P. sbc/350, 'glass '23, somewhere around 1900#. I'm thinking tires around 28' or 29" tall, perhaps Micky's or Hoosers. For that reason, the 4 coil set up looks like the way to go.

Do you think this would be compatable with quarter eliptics in the front?

Lee...I've said it before, your T is so dead on target. I can only hope mine will come close to that.

Thanks again for your input. This IRS is a new ballgame for me. I know I can win if you don't mind me picking your brain.


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