XJ XJ6 / XJR6 ( X300 ) 1995-1997

X308 rear monostrut retrofit to X300

 
  #1  
Old 05-24-2015, 01:14 PM
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Lightbulb X308 rear monostrut retrofit to X300

Although this has been mentioned in some other threads such as the following, I thought I'd start a dedicated thread to retrofitting the X308 rear monostrut to an X300.

https://www.jaguarforums.com/forum/x...rences-132521/

I just picked one up for $15, so I'm going to put it on my "I can't think of anything else to tinker with right now" list since it isn't any priority. Maybe I'll do this at the same time I replace my rear "A frame" corner body bushings with the X308 sport bushings I bought last year.

From the comments in the thread above, it is supposed to be a straight bolt-on affair to install this X308 monostrut, and gain some improved handling in the rear. Paired with the rear sway bar, this should really firm up body roll and improve handling.

One thing I wonder is if I should replace all four "metalastic" bushings as I have no idea how many miles this used monostrut has covered. Or perhaps by their nature these bushings really never wear out since they aren't subjected to the same kind of stress as say a shock bushing? Anyone have an opinion?


I have attached a photo of one of these "monostrut" units, a diagram from the X308 service manual showing the location/installation of the monostrut, a similar illustration showing the X300 single struts that the monostrut replaces (both X308 "mono" and X300 "pair of single" struts are part 13 in the diagrams), and finally an illustration by Japthug showing the benefit/function of the monostrut versus the two single struts on the X300.

Per Japthug:


It limits the movement of the rear axle assembly.

I drew a picture. As you can see in the pic, 2 strut bar hang the diff/lower suspension arms via wishbone tie, but when force is applied, the wishbone tie can twist and doesn't allow the suspension arms move properly.

When the monostrut is attached, it hold the wishbone tie firmly so the arms can swing properly, which gives stabilized cornering.

And yes, it is bolt-on.
Part 13 in diagram:

Part number for X308 "comfort" suspension: MNC3713AA
Part number for X308 "Sport/XJR" suspension: MJA3713AD


So I wonder if there is any way to look at the wishbone out of the car and see which one you have, the comfort or sport. For example Jaguar painted colored stripes on springs to indicate which was which. So I wonder if the part number or other identifier is present on the monostrut?

Either way, replacement bushings (part 14 in diagram):

Comfort bushing: MJA3715AB1
Sport bushing: MJA3715AB2

Oddly enough, the comfort bushing is more than twice as expensive, but both are still available.
 
Attached Thumbnails X308 rear monostrut retrofit to X300-01.jpg   X308 rear monostrut retrofit to X300-x300-struts.jpg   X308 rear monostrut retrofit to X300-x308-wishbone.jpg   X308 rear monostrut retrofit to X300-wishbone.jpg  

Last edited by al_roethlisberger; 05-24-2015 at 01:25 PM.
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Old 05-24-2015, 01:20 PM
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Answered my question about knowing which monostrut (comfort versus sport) and hence which bushings one has:

Blue bushings = comfort
Red bushings = sport

The metal outer ring is colored, and you can see in the photo of the monostrut above that I posted the bushings are blue, which means "comfort".



Again, not on my priority list, so I don't know when I'll get around to it. But if/when I do install it, I'll try to report on any lesson's learned, tip, or tricks.

....I'll probably have some questions along the way too, such as what I should expect to "fall off" and how to support "it" when I start undoing the two original single struts



.
 

Last edited by al_roethlisberger; 05-24-2015 at 01:28 PM.
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Old 05-24-2015, 05:49 PM
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I put one on my xj, I just used a Jack with a wooden block under the A-frame to keep the diff from sagging in the rear. It's a pretty easy straight forward job honestly. I also changed out the diff fluid before I did it because one of the curved bars on the new strut runs right in front of the fill plug. It looks like a pain to get the fill plug off with the clearance that is left with the new strut. Than again I don't have a R, not sure if they use the same differential or not between the supercharged and NA.
 
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Old 05-24-2015, 07:31 PM
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I will have to pull a monostrut next time a see an X308 at the junkyard. For educational purposes.
 
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Old 05-25-2015, 01:26 AM
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Originally Posted by knightofgold View Post
I will have to pull a monostrut next time a see an X308 at the junkyard. For educational purposes.
You will also find monostruts on some 96+ model year X300s. Both my 96 4.0s have them! Earlier one built approx. September 1995 (759xxx). I didn't see a change point (from the 2-strut setup) listed in the parts manual PDF. I thought the monostruts were put into regular production somewhere along the line in 95/96, but that might not be the case. Scarecrow's 97 didn't have one.

My 95 model year XJ12 has the 2-strut setup. It could use the monostrut. Maybe someday...
 

Last edited by SleekJag12; 05-25-2015 at 01:33 AM.
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Old 05-25-2015, 07:41 AM
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Originally Posted by SleekJag12 View Post
I thought the monostruts were put into regular production somewhere along the line in 95/96, but that might not be the case. Scarecrow's 97 didn't have one.
I thought the same thing. And I wondered for a while why mine had the struts versus the monostrut. I bought it from an older gentleman, who worked on Jaguars, and had a 95 xj6. I assumed either mine came like that or he swapped it out at some point in time.
 
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Old 05-25-2015, 10:38 AM
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Originally Posted by SleekJag12 View Post
You will also find monostruts on some 96+ model year X300s. Both my 96 4.0s have them! Earlier one built approx. September 1995 (759xxx). I didn't see a change point (from the 2-strut setup) listed in the parts manual PDF. I thought the monostruts were put into regular production somewhere along the line in 95/96, but that might not be the case. Scarecrow's 97 didn't have one.

My 95 model year XJ12 has the 2-strut setup. It could use the monostrut. Maybe someday...

*laugh* .... well I'll kick myself if the monostrut is already installed on my 97XJR

I'll have to go poke my head up underneath, but I don't recall seeing it when I was changing the rear shocks last year. But it's I didn't notice I guess since I wasn't looking for it.

I'll look later and report.
 
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Old 05-25-2015, 10:47 AM
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Originally Posted by al_roethlisberger View Post
*laugh* .... well I'll kick myself if the monostrut is already installed on my 97XJR

I'll have to go poke my head up underneath, but I don't recall seeing it when I was changing the rear shocks last year. But it's I didn't notice I guess since I wasn't looking for it.

I'll look later and report.
The monostrut was never used on the XJ6 XJR6 or XJ12. It was only factory fitted to the few manual XJR6 cars. It was used as a field fix to address the judder on the 4-5 shift. I always thought the cars handled better after they were installed.
 
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Old 05-25-2015, 11:01 AM
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Al, I'll buy yours off you. I need one and my 97 XJ6L doesn't have one.
 
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Old 05-25-2015, 06:56 PM
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Default No monostrut on 97 XJR

Originally Posted by al_roethlisberger View Post
*laugh* .... well I'll kick myself if the monostrut is already installed on my 97XJR

I'll have to go poke my head up underneath, but I don't recall seeing it when I was changing the rear shocks last year. But it's I didn't notice I guess since I wasn't looking for it.

I'll look later and report.

Verified, my 97 XJR does NOT have the monostrut.

.
 
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Old 06-07-2015, 09:36 AM
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I just got one. I'm going to check the condition of the bushings and install this and Polyflex rear sub frame bushings this week. Now all I need is a rear sway bar and associated hardware.
 
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Old 06-07-2015, 08:14 PM
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Great, let us know what procedure, gotchas and other lessons learned you discover taking the old pair of single struts and putting in the new monostrut.

I plan to remove the old "comfort" bushings from mine, have a buddy clean the monostrut up and have it powder coated, then I'll get some of the XJR/Sport bushings in before I install mine.

.
 
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Old 06-08-2015, 10:02 AM
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Dealer has the XJR sport bushings for $14.44 each (whse). Going to clean it up a bit and install either Wednesday along with the Polyflex Rear Subframe Bushing. I still haven't tracked down a rear sway bar. I'm also going to do the upper and lower rear diff mount bushings I think too.
 
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Old 07-10-2015, 03:08 PM
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Old 11-11-2016, 08:21 PM
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my 97 xjr has the monostrut installed,i will replace the bushings,undecided between oem sport,or powerflex...
 
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Old 03-11-2019, 10:45 PM
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I know this is an old link but I finally began to put my strut on my car and not having a lot of luck lining up the bolts. Spent the last four hours trying to get them lined up. Any suggestions on the process. Already changed out all the bushings.
 
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Old 03-12-2019, 06:09 AM
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Last edited by Lady Penelope; 03-12-2019 at 06:16 AM.
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Old 03-14-2019, 06:40 AM
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Originally Posted by cdma View Post
I know this is an old link but I finally began to put my strut on my car and not having a lot of luck lining up the bolts. Spent the last four hours trying to get them lined up. Any suggestions on the process. Already changed out all the bushings.
I think you'll need to force it, crowbar is probably a good idea. I've bought a monostrut recently too but I'll be replacing the wishbone tie as well at the same time to fit in rear anti roll bar(my LWB is missing it) so I'm hoping to bolt on top first and then get the bottom aligned.
 
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Old 03-14-2019, 09:35 AM
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I have a X308 monostrut sitting in the garage for someday installation

Not determined if I will rebush it first or the poly density to use or a premade source

Some thoughts came to mind on installing it as I took it out of a salvage yard donor car

At a muffler shop they have the pole jacks to place in certain areas of exhaust line installation this can be used in this application where the assembly weight sag or the coil springs preload have the holes off in the vertical direction

Another though was the spring compression tool kit at the auto parts store free tool loan program , thus would remove the springs reload

If the holes are or in the horizontal axis some of the cheap cargo straps from harbor freight with the final strapping pull over buckle as it tightens the strip dimension may pull things over

But then may be the case to get the inter bolts in first as the outer bolts are removed and working your way from the inside out

Could be the matter of placing the car frame on wooden blocks and using the jack under the center differential or off to the left side location then to the right

Some fine adjustment may be had by putting some heat on the assemble strut rods and expanding their dimmention

Some day I will " play " with this holding a beverage not made with corn syrup

But I'll probably be cussing with British words and accent

The threaded bullet I will probably get made at a machine shop on a lathe because making something out of tubing stock myself would probably be a disaster and damage the bushings
 

Last edited by Lady Penelope; 03-14-2019 at 10:14 AM.
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Old 03-14-2019, 10:09 AM
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Mine went in with no fuss. Car on jack stands, hydraulic jack moving things around to line up holes. Nothing bolted down tight until all bolts in.

Worth doing. Nice change.
 
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