I have an early xj6 300 sovereign with the shorter rear springs (7 coils I believe as opposed to 9).

Its time for one new shock at the rear (think the bush is fubarred). I am considering my options.

Did some searching for historic threads but couldn't find anything specific to my queries.

Lowest budget option

I know its also advisable to put a new isolator in.

Cheapest option is get one shock and one spring isolator.

Now for the higher budget options..

I could replace shocks & springs on both sides

Now my query - has anybody upgraded their rear springs from the early short ones to the longer later ones and if so what was your experience.

My only concerns with fitting updated longer ones are whether the car will appear to sit too high at the rear and whether there will be more body roll ?

or should I go for XJR rear springs ? i don't have a towbar at present but I do own a touring caravan, and if i fitted a towbar a stiffer rear might be better due to the weight from the tow hitch.

Just trying to consider all angles before I buy parts & have fitted to avoid regretting my choice. Considered doing the job myself but very limited time-wise and I'm using the car as a daily.

Thanks in advance for any advice

Kyle

 

Go with the KYB springs(there are two types for x300, normal and slightly thicker, they are around £75 for a pair of the thicker ones - RF6742), they work well, as for shocks, if you want budget look for used ones, often can get a pair of shocks for XJ8 on eBay in excellent condition for under £100. Think I paid £50 for a set of almost brand new bilsteins few years back. You'll be able to reuse big doughnut bushes but you will need a set of new shock bushes as originals are most likely toast, unless of course new shocks will come with replacement bushes(they often do). Both easy to replace, I'd say 2h a side if you know how to handle a spanner. You might need a new lower shock bolt, as sometimes they are seized solid and its just easier to cut them off but that's £15 per bolt from Jag and you can find out if they will come out or not before actually doing the job.

 

So x308 shocks will fit my x300?

Do you have the kyb springs you mention on your car?

 

The Bilstein original shock # chart coming

For the non - supercharged and non - V - 12 you will be using the B4 rating

 

Thanks for the replies, are the shocks handed? the suppliers I've looked at it appears the shocks are identical for either side?

 

The X308 shocks come in ride leveling with 1 master air pump and the shock assembly may have the air ports orientated a certain way dictating they all 4 are different

The X 300 does not have this ride leveling

The X308 in some cheapened versions may come in straight standard stand alone shocks with no air hoses , but I'm not aware of that

 

I upgraded the rear springs on my car about 2 years ago. 7-turn JLM11422 to 9-turn JLM12257:




Unladen, the new version spring was about 1cm taller than the original, which is what translated to the rear ride height. This year I added a second 6mm disc shim to the top of the rear springs to get a little more boost, and am happy with it.

If you think you will tow a caravan, the better springs would be a very good idea. New KYB springs would probably be the best, as Katar says. I am now using KYB shocks (new with the upgraded used springs) and I like them. Supposedly comparable to the Bilstein B6. Got a firm rear end now, to match the front!

Best to plan on doing both sides equally, especially if you want to change to different rate springs or shocks.

If you search used springs, you can use the JLM12257 or the JLM12342 (sport/supercharged, more firm). Both were also used on certain versions of the XJ8 and XK8 and will fit the X300.

 

buy factory donuts

 

Item # 5 ?

Or # 13 and 14 and lower bushing # 17

Genuine Damper And Spring Fittings-rear For Jaguar Xj 1995 - 1997 (from 720125 To 812255) Classic | Jaguar Land Rover Classic Parts

 

I also have recently installed a second 6mm packer to each rear spring as well as new OE upper donuts and lower isolators. I retained the original 7-coil springs and am happy with the height. The previous owner put in new black Bilsteins (B4?).

I'd rent a truck long before I would consider towing with the XJ, but maybe that's the USAian in me.

 

It is worth bearing in mind that the front springs can get a little tired too, affecting ride height.

 

The bottom shock bolts are M14, does anybody know what length they are? Thinking of getting some before the job in case originals rusted/seized.

Do I need to get the specific jaguar part or should it be sufficient to get one of the correct length ?

I know the actual part number is JZB100036

 

Suspension bolts are high strength and not what you will see at the hardware store

If you're by a wrecker you can pull some to be prepared or least know where to find some

 

I've got hold of a set of the thicker rear kyb springs.

Does anybody know the part number for rear kyb shocks and are there different versions from kyb ?

 

KYB KG6797 Gasajust (rear) is the upgraded type for the X300 that I have installed. Ironically, they are not adjustable! They claim "increased handling" and up to 25% more damping power over OE. KYB has one called Monomax, but that might be too much damping for the X300. Use KG4730 for the front.