Hey all!

im new here. Newly hooked on these cars. Have an xj6 lined up for the summer (friends car he’s selling me) if this virus doesn’t bankrupt us. So I have a 1986 XJS front suspension in my old Chevy (please don’t kick me out cause it’s not a jag) and am doing some tuning and need to know if the lower control arms in a series 3 XJ are parallel to the ground and a if not, what angle? I am thinking the suspension is way, way sprung due to my Chevy being lighter. The control arms are playing down 13° Assuming 0° is parallel

thanks

 

Is the road wheel upright ? As I recall the lower wishbone should not be parallel to the road when the car is standing, there will always be some angular displacement. Of course if the engine weight is way less than the original XK engine, then the car will sit higher. Maybe you need a couple of bags of cement hidden under the wings !!

 

Lol cement will help. I’ve only got a small distance between the bump stops so I’m sure it’s not right. It’s on its own weight. The car is like 3200lbs I think the Xjs was about 4000 wasn’t it?

These are 13° Pointed down. So they aren’t parallel to the road in a stock series III? Do you know what the angle is or perhaps if it’s not too much trouble, can you send a photo?

 

I don't see any big problems. The front wheel reveal looks good, the upper bump stop looks good, and the lower arm angle looks pretty good. I might be concerned about bump steer if the tie rods are not pretty flat. I take it that you are just putting it together, you haven't driven down the road yet. As Fraser mentioned, the road wheels in front spec at 1/2* positive camber, give or take a quarter degree.

Dave

 

Thanks for your reply. I had assumed that was a bit “sprung” as the arms are so pointed down and the bump stops are so close. Those are xjs v12 springs and are the firmest. I believe I need softer than the softest which Assuming are xj6 springs I figure I can have them made, pending the cash flow starts to return. They aren’t that bad. I just was hoping to match the stock angle for control arms. If I go down 1-2” even better. I want a soft ride... think 70s buick

 

You've got a nice looking early '50's Chevy and an ambitious front suspension swap. Good luck.

Dave

 

Thanks!

believe it or not, it’s extremely straightforward. Seems like the engineer on this jag front end was a 49-54 (-62 corvette) owner lol.

the lug pattern is the same, brakes fit under stock Chevy wheels, clears frame rails. Rack spline is 1/4 inch away from frame - right where it needs to be for anyone that had manifolds other than mine (lol), 4 holes in the jag line up exactly with 4 holes in the Chevy (one per corner), track with almost spot on

the old one drops out with 2 parallelogram plates and 16 bolts. Recreated the plates and will be welding then to the jag. I did think of soft mounting it with the jag bushings and pads but for the sake of ride height and “simplicity” I’m going with the plates

 

Nice work!

Dave

 

1. Brings back memories. Somewhere between 49 and 52. Nice cars. Late 54 I swapped my 52 MG TD for a Belgian assembled 60 Chevrolet four door. Black. Terrible tires got replaced with WSW's. A very nice car. Heat and tunes, the TD had neither!! I was stationed in Germany! Whe discharged, I brought it home.. NY to El Paso, Texas. Three days. Sent wifeand newborn daughter ahead aboars American air Lines. Knew not to push the babbit pounder past 60. But, it wasa OK for miles at a time, all day an a lot of night!

2. The angle of the arms looks about right to me. More down travel is usual in my opinon. It has plent. Up travel is less so the amount looks adequate.

What is under the hood a better 235 or a SBC?

Carl

 

Thank you everyone! I hope I am not out of line by starting a Chevy conversation on a jaguar form, only the utmost respect for these vehicles. So badly want a series 3! It’s a small block Chevy now, but that’s another problem… We’ve just about killed that engine, and we are hopefully, if this virus doesn’t bankrupt us, going to put in an early 2000’s 5.3 fuel injected V-8 in computer controlled four-speed automatic. Same weight as I have now, though. I did a substantial amount of research:

Thank you everyone! I hope I am not out of line by starting a Chevy conversation on a jaguar form, only the utmost respect for these vehicles. So badly want a series 3! It’s a small block Chevy now, but that’s another problem… We’ve just about killed that engine, and we are hopefully, if this virus doesn’t bankrupt us, I’m going to put in an early 2000‘s 5.3 fuel injected V-8 in computer controlled four-speed automatic. Same weight as I have now, though. I did a substantial amount of research:





The jag is way too stiff. It’s:

4.90 id
.66” spring thickness
6 3/4 turns
Roughly 11.5 height
Roughly 7” installed height (in jag)
466 pound rate
Not sure if load but guess around 2,000.
Square ends (meaning the last coin turns down into itself)

Those are all pieced together from much research


The Chevy spring specs are readily available:

Bar Diameter - Inches 0.59
End Type 1 Square
End Type 2 Tangential
Free Height - Inches 14.22
ID - Inches 3.22
Installation Height - Inches 9.50
Load - lbs 1625.00
Spring Rate - lbs per inch 344.00
Spring Type Constant Rate


SO IF I CAN find a donor vehicle with a spring 10-12” tall, 4.9 id spring with 6 or 7 turns and a rate around 344, load around 1625, it will go in the jag front and give a ride firmness almost identical to Chevy. So far, NOT so good. Searched the mood catalog and got close, but the best was 15” tall. Would make the jag too high. Looked a What felt like a million springs on rock auto too.



The other thing I should mention is that, well most guys doing a build like this are excited about better handling and cornering, all of my intentions are on maintaining that soft floaty 50s ride. I have exponentially more faith in the Jaguar front and then Camaro or Mustang two. The latter two were lighter than my Chevy, and economy cars. Yes, sporty, but they were economy cars. The Jaguar way to thousand pounds more than my car and was stable at 160 mph, while delivering a fantastic ride. Seems to me the much better starting point. Also, much less work than a Camaro. I have a virtually brand new 1967 Camaro frame in storage. I am going to sell it. I am also going to stock up on Jaguar front ends, because any other American 50s car that I build, if I’m so blessed to have the opportunity to again, will be Jaguar

 

my Babbitt pounder HATED me lol we drove that car EVERYWHERE. 75mph and it was painful lol. Got it with 40,030 miles and killed cylinder 5 by 48,000.

 

I have a S3 car and l find the ride absolutely delightful.

I wanted that same ride on my '49 truck, so I swapped in the front suspension off of an XJS using the same rubber mounting used by the Jag from the factory.

First, here's what I did to set the Jag crossmember in the GM frame:

The correct angle of the front cradle for transplanting in your Chevy sedan is the one that gives you the correct caster angle.

To get the angle/position correct, I took the shim stack out of the front upper ball joint of the Jag's suspension and re- installed it so it was even on both sides of the joint - this puts the caster adjustment at the nominal position.

Next I slid the Jag cross member under the truck and connected the rear rubber mounts of the cross member to the GM frame with a bracket. I put a trolley jack under the front horns of the cross member and jacked it up until I had the factory caster angle, which IIRC is about 3.5 degrees (you can buy a camber tool on ebay). With the frame level, the suspension at the correct ride height and the built-in castor angle set, I simply built a bracket to connect the two rubber eyes on the Jag to the truck frame.

This is the bracket I used to pick up the rear rubber mount for the Jag. Note the all-thread that replaces the spring to hold the Jag suspension at ride-height for the install and setting caster.

After setting the castor angle with a caster gauge that attaches with a magnet to the front wheel hub (you swing the wheels left to right and read the degrees on a bubble) this is the bracket I fab'd to attache the Jag cross-member to the GM frame horns

This photo was taken at the body shop, so it was pretty dusty. Final design has three grade 8 bolts holding the bracket to the chassis.

On the issue of spring rates....

Comparing the Jag spring rate to that of your Chevy's is apples to oranges. It would only be relevant if the geometry of the Jag suspension was exactly the same as the Chevy. The angle of the spring, where the spring exerts its force on the a-arm, length of the a-arm and other factors, I'm sure, determine the spring rate needed.

If you're Chevy weighs about the same as a Jag, a XJ6 spring should give you about the same ride as a XJ6 - I wouldn't worry about the spring rate. I put an iron LS 5.3 in a XJS a few years ago, and it rode fine with XJ6 springs in it, but I did have to clip them to get the ride height. In retrospect I should have modified the spring pan so I could shim the ride height, but I was jonesing to get it on the road. Here's a Jag spring pan modified for an airbag, but with a cup welded to it to retain a spring/shims it would work.



To get the Jag ride, you should use the Jag Boge shock or the Monroe for the XJ6. I have KYBs and they are too harsh. You'll need to fabricate a shock mount like this (sorry for the sideways shot)


Here's a photo of the final product. It is on airbags right now, and I'm pretty disappointed in the ride quality - it rides like a truck, not an XJ6! I have some tricks up my sleeve to try, but if it won't ride plush like the Jag, I'm going back to Jag springs and Boge/Monroe shocks.


The 5.3L V8 that powers it. Note how close the steering shaft connection to the Jag rack is.. You'll need to consider this too.


There is a FB group for Jag suspension swaps, mostly dominated by Ford trucks. There's also a Social Forum on the HAMB for Jag suspension, but it's languished since Ryan doesn't think it is 'traditional' enough.

 

This is AWESOME. thanks! Very good build and great read

I really appreciate how helpful you and everyone else has been especially given the fact that this is off topic.

a coupes questions

for ride height sake, I cannot use the rubber eye bushings and rear pads. I’ll be using the same 8-bolt rectangular plates that bolted the factory Chevy suspension. Picture of someone’s crossmember and where the plate will be welded

the horns (front eye bushes) aren’t outside of my frame but rather in line with it so it would make a difference for sure. i have a top-hat Frame so it would likely be 1/4 plate bolted to the bottom of my frame. The rear would be almost impossible but that just makes it more fun. If I can do it.

Also, the Jag double knuckle unjoint thing was required for your steering connection right? What did you do at the top of that to the column?


Many many thanks

 

Oh I forgot

i was told there is about “50lb” of spring in the jag shock, and also it won’t clear my inner fender. I guess I have to pony up and get an adjustable shock for something like a ranger ad that’s the exact size and design i need
but very doubtful it’s the ride I want

 

Well, regardless of how you mount the Jag cross-member - rubber bushings, plates or weld - set the angle with one of these to get the correct geometry-

Longacre Caster Camber Gauge 78260

I didn't put the Jag 'double knuckle' in my steering linkage. I've been driving it about a month now and I can't feel any movement up through the column. Mine has two universal joints - one Jag spline to double-D and the other double-D to double-D

The Jag rack has a input spline that's a little unique, but you can buy steering joints with the Jag spline to double-D from Borgeson or Sweet IIRC. (maybe Speedway too)

The steering column in mine is from a 50's Cadillac. I shortened it about 18" and installed a 'column saver' which is a bushing and a thrust bearing that replaces the bottom end of the column. The last one I bought I got from Eckler Truck Parts. I ground the steering shaft for the double-D joint with an angle grinder and a file. The universal joints are pinned to the shaft to keep them in place. If you go the 'column-saver' route you'll need to support the shorter column at the floorboard. This is a collar that secures the column to the toe-board. The oval thingy is a stainless trim ring to hold a boot to keep hot air out of the cab



If you want the Jag's ride, you should try and duplicate all the suspension geometry, including the shock and tower. I don't know if it is equivalent to 50# of spring, but the stock Boge shock is gas charged, but it doesn't have any effect on spring rate - it is only there to keep the shock fluid from entraining air. I'd relieve the inner fender to make the factory shock arrangement fit. You can make a little clearance with a hammer and dolly in just a few minutes if you just need a little space on the inner fender. If it is a lot, just cut the inner fender away and make a 'blister' to cover the intrusion.

Gratuitous picture of my XJ6 to throw the forum moderators off.


I've got a build thread on my truck and the Jaguar suspension and it might be best to continue the discussion there if you have additional questions

https://67-72chevytrucks.com/vboard/...d.php?t=725080

 

That jag is gorgeous. I want one so bad. A fiend offered me an xj40 but I think I want to wait for a series I-II-III to come along. I can tell they are going up in price.

I ordered an inexpensive version of that caster:camber finder. Sooo much less redneck then when I used magnetic angle finder to do my 54 front end alignment haha

I’ve been told the Chevy frame and jag crossmember touch in a way that gives perfect caster. A GM engineer from newzeland did a write up on this but he passed away recently so can’t ask till my car is passed onto my son (lol)

I am 90% certain the top of the crossmember is 180° to the ground in the jag

I’ll check out your thread! I get it that this isn’t particularly appropriate here / in fact I’m grateful and surprised by the kindness here. I’m belong no more on the Chevy truck forum than I do here, though

though soon this will home. I no longer have need of a daily driver and am likely going to sell me 2002 Lexus. I can get an xj6 with that money

 

My Xj6 was the most reliable car in my fleet till I bought a Toyota. It gets used regularly to fetch parts for the rest of them.

I'd think twice about selling a Japanese car and replacing it with an XJ6 though. The Jag can be reliable, but it requires frequent tinkering. If you don't have time or inclination to play with it all the time, it will soon become 'yard art'. If you're patient you can find them very cheap that have deferred maintenance and the cost of professional repair (if you can even find a shop to work on it) is more than the car is worth. They can be had for next to nothing if you're patient.

If you're mechanically inclined this board can be very helpful in bringing one back to life - there's 40+ years of experience to tap here.

 

True. That Lexus is awesome and rides like dream but it barely gets driven as I always have something from our small dealership to drive. I probly will keep it

I am not saying this to be arrogant but rather, blessed... I haven’t come across a job that doesn’t require machining that I can’t do. It’s how I got my Lexus dirt cheap. Needed “$3000 worth of stuff done” that I took care of for $500 plus my time. I do hope to come across a series iii or even a ii. I so love the lines and now that I’m elbows deep in the front end of one, I can say I love the engineering