my '89 sports pack V12 didn't have one fitted

but i have always debated installing one, but then again i don't go racing round the streets in her....



BB

 

Well, you certainly don't have to go 'racing around' to enjoy the improvement a rear ARB makes. You'll feel it whenever you turn a corner!

But your reply is, IMHO, what Jaguar was anticipating when they stopped installing the bar: nobody will know, nobody will care, we can save a few dollars, everyone's happy


Cheers
DD

 

Good shocks are a must, but I think standard springs and ARB is the way to go. Standard springs keep the compliance and will allow the tyres to maintain contact with the road in less than perfect tarmac.

An anti roll bar (ARB) allows softer springs to be used, giving a more complaint ride, as the ARB allows both wheels to move in bump and rebound together with no effect.

When the car rolls, as in a corner however the ARB then (in effect) transfers spring rate from the wheel in rebound to the wheel in bump, effectively stiffening the wheel in bump.

There is also a difference between the Jagsport and TWR Bilstein dampers. The TWR units had softer bump valving and what I have fitted to my car.

 

I have front and rear bars fitted from Addco. You will see the part numbers on their site. They fitted up without any drama whatsoever.


BUT, you will need to fab the rear trailing arm mountings. I used a pair of adjustable end links I found from someone's post on the JL list. These have a rubber mounted eye at one end and a rose/heim joint on the other.


The brackets were pretty easy: I bought square tube stock at Home Depot which had an inside dimension just about perfectly matched to the bushed end of the end links I purchased. Easy to fab the brackets from that- sawing and drill ops only. Then I bolted those brackets to the trailing/radius arms (drilled two holes in each arm).


My car had the bar mounting studs- most XJS' do, I think (just had to chase the threads with a die to clean them up), and the brackets and bushes supplied with the bar worked fine.


This fit perfectly. The end links, because they were adjustable, could be dialed in to fit just right.


I like the effect for 95% of the driving I do. When the car is pushed hard, I can feel this lifting the outside rear wheel on tight, fast turns, and can easily see the car breaking loose early because of this if you are not careful. Rain is even more treacherous, but XJS drivers know this already. I think this the reason most who track this car dispense with the bar and concentrate on spring rate and damping: more of the tire stays in better contact with the road.


But, 95% of the time, this setup is really great- very flat, very stable (as long as you don't over reach!), like slot car. Very happy with it. And stiffening springs and damping was not where I wanted to go on a convertible, as you have to be careful with this model or else you will utterly ruin the ride and overall shake. Coupes are much more tolerant of this approach.


I was concerned too, like the other posters, that this would be difficult to fit, and making the brackets and so on would be a chore. Ended up being a lot easier than I expected.


Finally: if you don't have the early model OEM trailing arms with the end link ears, there are many ways to set this up. I have seen ears welded to the small end bushing end of the arms, welded to the arms near the OEM location, bolted brackets (like I use, and then again, brackets that were fabbed very differently, too), and I have even seen a case where the owner dispensed with the trailing arms altogether, having found another way to locate the cage, and used the bolt locations on the hubs where those trailing arms attached as the mounting point for the links.


The message is, the absolute location doesn't seem to matter all that much, as long as it is somewhere in the vicinity of the lower hub. But get adjustable links if you do it that way.


-M

 

Hi Paul

That sounds a really good idea, what adjustable Shocks would you recommend.

 

Cheers Doug

I think I'm inclined to agree with you there.

 

OB,

I run Gaz adjustable shocks. I had one set fitted and loved the ability to set the ride using these adjustable shocks, but wasn't really happy with the slightly reduced ride height when using DB7 springs.

Gaz then brought out an adjustable platform shock ( it uses a threaded body and the spring platform collars can be adjusted up or down to enable ride height to be set precisely. I changed mine for these new ones, set the ride height to original Jaguar spec, played with the rebound setiings for a day until I was comfortable and it's been happy days since.

Paul

 

Cheers Paul

That sounds the best way for me to go.

 

They are indeed still around. I've just had fitted a Harvey Bailey ARB and anti tramp kit. Whilst my R-S coped pretty well with the twisty stuff before, the handling is now absolutely superb. I cant really quantify how much better each item has made it since I refurbished the IRS at the same time, but, now - WOW.

They aren't cheap - but what a difference...

 

Could you post some pics please Beavis, and a link to HB?
Thanks, Greg

 

I had to take a look under my old '77 XJ-S yesterday. Yes, it has rear ARB

 

Whether you go with spring rate and damper tuning, or add a rear bar, it's horses for courses, really.


After all, when Jag introduced the XJS, they did so with a rear bar, having run the IRS design for many years, and so were well informed as to the trades as far as spring rate and dampers vs. bar. The fact that the bar was later deleted, and then reintroduced on sports models and again deleted tells us one or two things: either the efficacy of the bar vs dampers/spring tuning was an either/or thing, or, it was driven by cost. The bar and brackets and links add up.


But as to the question of how to set up the suspension, or the addition of a rear bar: it is best to begin by renewing or at least verifying the integrity of all the suspension bushes and the front and rear mounts. Most owners will find one or more bushes and mounts in need of replacement. Then, shocks. Since it takes a set of 6 to do this car it is pricey and many owners delay too long on this. Finally, often the rear springs become saggy, and those should be replaced. And all of these things should be attended before considering whatever else one wants to do to the suspension.


BUT, if we limit ourselves to the rear, and ask the question: which is the way to go, rear bar or revise spring rates and damping: I suggest, again, given Jag's own conflicted behavior on this point, go whichever way you want. The cheaper way will be the bar. A set of GAZ damping adjustables, with the adjustable perches will set you back a few bob, but certainly will give you the ability to dial in the damping and ride height.


Myself, I blanched at the cost of those shocks, and put new OEM spec shocks on instead and fitted a bar, making sure the springs were still in spec at the time as well. For street purposes, you get 85+% of the way there for substantially less cost.


My 2 cents.

 

Greg, here's the link.. will post some pics up for you a little later...

Harvey Bailey Engineering Ltd Home

Rich

 

My 89 was delivered without an ARB even though it has the sport pack!? I'll be looking into this too, as I like my cars to be complete

 

same here ,

though i have fully adjustable dampers on the front and back at the moment,

i actually have a HBE quick-rack steering rack that has never been fitted in storage as well , and i have a quick-rack already installed in the car ,

i have everything to fit the rear ARB , except for the bar its self , so might be tempted by the ones on ebay as above

BB

 

Hi

Thanks, that's very good advice, as I never considered the cost until you brought it up.

Its bad enough for a re-core to do a Radiator, so shocks must be a really outrageous price.

 

OB,

It's worth doing the sums carefully. Remember if you're doing either the springs or shocks on the rear, there's no more labour to do the other, and if springs need replacing, then shocks will as well.

As we know, springs and shocks are a minefield with large numbers of rubbish pattern springs out there that will sag within months. Only use really reputable springs.

When it comes to shocks, there's a whole range available in the UK where you are. And prices can be surprising from quite cheap to very expensive. I'm not sure who made the sports shocks for the pre-facelift convertibles but as an example: sports shocks from Jaguar £106+ vat, Bilstein B6 £178, Gaz adjustable height £105.

So time to sit down with a calculator maybe?!

Paul

 

Agree that having all bushes springs and shock absorber in perfect condition before deciding that you need suspension upgrade is a good approach.
Many owners, including me will have XJS with suspension components years old, past there best and possibly have never driven an XJS in perfect condition as it left the factory.

Having said that, if upgrading shock absorber my preference in increasing order of quality and cost (in my opinion)
Spax adjustable

Bilstein adjustable

Ohlins active (electrically controllable) , possibly the last word. Cost , if you have to ask then you (& me) probably can't afford!

 

There is KONI

 

I have a set of clips, that bolt to the rear IRS strut right next to the rear radius arm ( no removal of the arms and welding required) that allows you to bolt to it and allows the same mount at the existing studs (hanging down) unused. In the UK...I think Harvey Bailey has a similar design......PM me if you want a set from the US. Use the original struts from Jaguar breakers, along with the links....per.....The Grant of Francis of OZ, Best, JW