Also looking to get some further thought from folks here. Reading through the forums there are several recommendations. Using XJ6 springs, getting KingCoil, removing spacers and some incomplete discussions (as far as I could find) regarding cutting existing springs.
There are no spacers now on my XJ12 converted to V8, so this option won't work for me.

If at least one end of a spring is tangential, then cutting up to 2" lower should be possible, yes?
I have not torn my front apart fully yet, in next few weeks I hope, but in looking at the springs as they are installed and at parts photos, it looks as though the bottom is tangential and the top square. Can anyone confirm this?
As part of my need to lower due to the V8 350 conversion, I would be best to go to the full 2". The front is essentially near 4" too high at rest as is, with the correct wheels and new tires.
The KingCoil springs that have been recommended, and as shown by steve_schmidt, are to provide about 1 1/4" lower height from original ride. In my initial thinking, I would rather go 2" or even just a bit more and add spacers if needed. And also to not go past my budget on the front. Modifying the existing would be the cheapest, if viable.



Any feedback is appreciated.

 

Robert,

The King Springs spec is 30 to 35 mm or about 1.2 to 1.4 inches. I saw about a 2.0 inch drop with the set I put in. My wishbones had 2 spacers which I removed. If each 1/8th spacer removal lowers the car 3/8ths (as suggested earlier in this thread) then all the numbers add up. 1.2 to 1.4 inches +3/4 inch for 2 spacers = 1.95 to 2.15 inches. Floor to the top of the wheel arch was originally about 28 3/4 inches. After the drop it is about 26 3/4 inches. The 2 inch drop is a little too low with the 225/60/R16 wheel and tires I used. The original tires are 205/70/R15 with a tire height of 26.3 inches. The 225/60/R16 is 26.6 inches. The clearance seemed OK at first but every once in a while, when making a hard turn up a driveway entrance, I get a slight rub. I would say from my experience that 2 inches is just a little bit aggressive. I plan to put one of the shims back in which will reduce the drop (raise the car) by about 3/8 inch. Since you don't have any spacers to remove, you could use the King springs with a 1/8th to 1/4th spacer between the spring plate and the wishbone. This would lower the bottom of the spring below the original mounting point, giving you 3/8ths to 3/4ths of an inch greater drop than the King springs themselves, or about 2 inches. I probably sound like a King Spring salesman, I am not, I have no affiliation. However, I do like the way they ride and handle. There is much less body roll in and out of corners than with the original springs. The front end is a little stiffer and more responsive without giving up the smooth Jaguar ride. Spacers are easy to find....

Steel Spacers Products - Marshall's Hardware


Hope this helps..

Steve

 

A simpler and time tested method of dealing with this, is to swap out the XJS springs and install a good used pair from an XJ6.


When my XJ was still a 6, the nose was pleasantly down just a tad. When the "big" 6 left and the LT1 replaced it, the nose went up just a tad. I forgot the spec. But, I measured it at the time. It was right on.
I know how to lower it and not butcher stuff. But, I've no plans to do so.


I'd get a set of XJ6 springs from David Boger at everydayxj. Good guy, lists here.


Not to discard Steve's post. Definitely, a useful option.


Carl

 

This would apply to the XJ12 too? That is what my car was original. A set of XJ6 springs is reasonably priced. I think I will go this route first.

 

I very much appreciate your detail on this!

 

Robert,

There is a comprehensive list of engine weights on a Morgan Forum at...

engine weights

It lists a V12 at 680 lbs, XJ6 at 605 lbs and SB chevy at 575 lbs. So the XJ6 springs are expected to hold 605 lbs at ride height. While you only have 575 lbs of load, the XJ6 springs will probably get you much closer to stock ride height than the XJ12 springs since they are expected to hold 680 lbs at stock ride height. If you just want to get back to stock ride height, then a set of XJ6 springs will probably suffice (add a 30lb weight to the air cleaner and you will be spot on! ) . If you wanted to go lower, then you have to go with a lowering springs like the King springs. I still have my XJ6 stock springs. There was nothing wrong with them, I just wanted a lower stance. If you are interested in them let me know.

Steve

 

Steve,


Last night I purchased some XJ6 springs, but thanks for the offer.

The reasons I did not go with the KingCoil springs was 1) the 30% stiffness and 2) the est. 30mm lowering.
I did not want to introduce a stiffer ride; this is going to be a cruising vehicle on mostly straight but rough, rural highways. And 30mm in my case seemed to be insufficient. Sounds like most folks are OK with the 30mm, for some reason, my height is nearly double what most have experienced post conversion.

 

Robert,

In your last post....

And 30mm in my case seemed to be insufficient. Sounds like most folks are OK with the 30mm, for some reason, my height is nearly double what most have experienced post conversion.

I guess my explanation wasn't quite clear. Overall the King springs will dro the suspension much more than 30mm.

King lowering springs are designed to lower the stock XJ6 suspension 30 to 35mm. They have 2 separate offerings, one set for lowering the suspension if you are keeping your XJ6 engine and the other for lowering the suspension if you are replacing the XJ6 with a SB chevy. What you have is a bit different than either of these cases. You (or a PO) put a SB chevy in place of a V12. It sounds to me like the stock XJ12 springs are holding the suspension about 2 inches above stock ride height because the SB chevy is around a 100 pounds lighter than the V12. According to Carl, if you replace the XJ12 springs with XJ6 springs, you will get rid of the excessive lift the XJ12 springs are providing and get you back to stock ride height since the SB chevy weight is closer to the weight of an XJ6 engine. Now, if you were to use the King spring to replace the XJ12 spring, it would give you an additional 30 to 35 mm (1.2 to 1.4 inch) drop over replacing it with the XJ6 spring. So in your case, I would estimate that replacing XJ12 springs with the King springs will drop your front end 3.2 to 3.4 inches from where it is now. Or about 1.2 to 1.4 inches below stock ride height. So your options are to drop around 2 inches with XJ6 springs (stock ride height) or 3.2 to 3.4 inches with King springs (lowered ride height). Does that make sense?

Steve

 

Or, on a lot of other cars. 5 mile bumpers??? But, they do "work" as designed, at least till the "stuffing" hardens.


I'm not estatic with ones on my 83. But, the rear one has taken a couple of whacks with no ill effects.


So, I just live with them....


Carl

 

This thread/ build may be of interest,
https://www.jaguarforums.com/forum/x...ys-xj6-180374/

They modified the rear suspension to an interesting cantilever setup and the front has an upside coilover.
I'd be very interested to know where the front coilovers came from, i want one.

 

IIRC John at Johns Cars specifies using xj6 front springs when converting an xj12. And I think they used to be included in his xj12 kit.

 

It seems all the mods I have done to my '71 XJ 6 -have my front a little higher than I like. SBC with aluminum heads, aluminum/plastic radiator, lighter trans 200R and other aluminum stuff involved. No spacers are under my front springs.. will just do the "put spacers under the spring pan" sometime in the near future. Want to finish my car up by Christmas this year.

 

ah, look what i found, the 'petrolicious' drift jag are selling a kit
https://xcessivemanufacturing.com/ja...nsion-716.html

 

That's cool but for one concern. If using a lower setting the axles will be at an angle past parallel at static ride height. Hard on u-joints.

 

that is an over-the-top modification , but sure looks KOOL.