RE : RE: [Lumps!] RE: rear sway bar upgrade

Ok, Now, I see what you mean.
Think about this …
How much does a modern car weigh?
The XJ-S, is close to 2 tons, if not a few pounds over…
thats twice what “modern cars” weigh.
Would you expect a van to perform like a sports car?
Of course not! The XJ-S is sportier than the line of other
luxury cars, but it’s no Porsche. It’s a Touring car.
Built for comfort, and with some handling characteristics.

Putting the rear bar on , will probably not hurt, but don’t
expect this to stop the front end from rolling.
at most it will probably just let you go round a little quicker,
before losing grip. The front end will still roll…

The way around this is redesign the suspension, shocks, springs, etc.
which you, don’t want to do. Much too expensive.

Most people will say …if one bar is good, two are better…
This isn’t the case.

Sorry if this isn’t what you’d like to hear…


Lumps Admin.> Being used to modern cars coupled with a like for more ‘spirited’ driving I

have found the car rolls excessivly on corners. I want something that stays
a little flatter, without going to mad on costs etc.


Dave 2000

-----Original Message-----
From: []On
Behalf Of Charlie
Sent: 07 February 2002 01:49
Subject: Re: [Lumps!] RE: rear sway bar upgrade

David ,
Most likely, But… Just a question, if you will, for the info of
What do you expect to accomplish with the addition of a rear sway bar?

Reason: front and rear sway bars, are a team. they are usually matched
with other suspension components, and additions of items without
careful planning can deter from the cars stability. If you add a rear
you may have to increase, or decrease, the diameter of the front

Sway bars, after a certain point in size, can unload the inside tire
causing a tri-cycling effect. This actually reduces handling. They can
also account for darting on irregular road surfaces. A sway bar should
compliment the handling package, not be the package.

Understeer is when you attempt to turn the car into a corner, but the
car goes straight. In the old days, the solution was to stiffen the
front end with a massive sway bar and then stiffen the rear end with a
massive sway bar. . Why both? First: The front suspension is under
sprung so putting a large sway bar on the front made a difference. This
does not mean that big sway bars are the answer. However a large sway
bar with stock springs does make the car handle better. Second: Because
the front suspension with a larger bar has less understeer. Yes it is
less, however it still has understeer. You need to make the rear end
slide around. If you can’t do this with horse power, you will have to do
it with suspension. So you install a massive rear sway bar.

This was for old technology, using a solid axle.

I.R.S., is an entirely different animal.
If you correct the front end geometry and install correct front springs,
correct front sway bar, alignment settings, shocks, and a proper wheel
/ tire package. The front end will not tend to understeer but it will go
where you point it.

Back to the original question, if you use upgrade the front, without
doing anything to the rear,
or just add more bar to the rear, the car will feel unstable in the
rear. It feels like it will want to oversteer on corner exit. Putting a
massive sway bar on the rear will make the car’s rear end come around
(oversteer). The reason why the car feels loose in the rear is because
lateral control on the rear suspension is not adequate. The rear end is
steering itself out of the corner.

Hope this enlightens a few…

Lumps Admin.
Customized 83 XJ6 /350/700R4/

----- Original Message -----
From: “David Hodges”

Can this mod be applied to my series II XJ 5.3C?


Dave 2000 1976 XJ 5.3C Essex UK

-----Original Message-----
From: []On
Of Steven Kee
Sent: 05 February 2002 13:36
Subject: [xj] rear sway bar upgrade


You need the XJS radius arms, swaybar, end links and mounting
brackets that
go around the bar and attach to the underside of the body (not the
You will have to trim the exhaust heat shields above the mufflers.
You will
also have to remove the rear set cushion to mount the bolts holding
in place. I have an article that was in Jaguar world a few years back
details this upgrade, I can fax a copy of it you.

I have also upgraded the front brakes to the 4 piston caliper setup.
want to do this take the complete ball joint to ball joint front
with steering arms. ( where that new rack bolts on to!!:wink: WELL Worth
Grab the master cylinder too!! and the pipes that do to it, you need
weird fittings, so when yours goes, you can upgrade to a cheaper

Good luck!!!
1972 XJ6 Series 1, in the process of Lumping!! :wink:

Steven Kee
On Power Systems Inc.
905-881-6644 x24
fax: 905-881-6652
cell: 416-526-2850

The archives and FAQ will answer many queries on the XJ series…

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