Hi Guys

I am considering Retro Fitting my 1990 XJS that has ABS

With a Brake Booster System from another Car because my ABS Pump has burned out

Where the only problem (from my point of view) is that the operation of the Brake Light Switch is different

So either I'll have to improvise and rewire it in some way or else my 'Preferred Option' would be to Swap the Brake Pedal, so that I can keep the existing Brake Switch

Is it possible to do that and if so how would I do it ?

 

As Greg and I have been saying: yes you can.

 

Hi Daim

That's not quite what I meant

I know that you can Swap the Complete unit but an XJS with the Brake Booster System doesn't 'AFAIK' have the Peg sticking out of the side to operate the Brake Switch setup like on an ABS Car

So I am talking about the Pedal ONLY not the complete unit

 

Please, please, please stop looking for ways to avoid fixing the original system on your car! It was built to have the system it has, so messing around with braking systems is ill-advised. Plus it will probably make the car ininsurable or, if you don't declare the modifications to your insurer you will, unquestionably, invaidate your insurance.

 

Hi Bladerunner

Definitely food for thought but I'll have a word with my Insurance Company and see what they say, as they have been using the Brake Booster System on these Cars for years

 

May I ask why you are going down this route when you can pick up a working ABS pump on ebay for less than £100?

 

If you need parts ob , pm me I may be able to help but surely the main breakers have a pump?

 

I am a little bit dubious about buying a second hand pump on an Auction Site in case it was giving trouble before they decided to sell it

The Brake Booster System is simpler and so much more reliable and I'm also not a big fan of ABS

 

Hi Brinny

Cheers!

I've very rarely seen an XJS in a Breakers Yard but I'll keep looking just in case

 

Because before the normal breakers get them, the specialists, like Simply Performance and Just-XJS buy thrm in the UK. There is no such thing as XJ-S models on the scrap yard here.

 

Hi Daim

Cheers, I thought as much myself

 

You have plenty of protection from ebay as a buyer.



Bear in mind that these pumps are not failing left-right-and-centre. You have been unlucky to have one fail, let alone two, so I understand you may have the impresion that they are unreliable and all failure-prone. But you also have cars that have sat for long, long periods of time.



This system is really common and in all my years of having Range Rovers with them (probably 20 years) I haven't head of them failing or had any problems myself.

 

Hi Bladerunner

Cheers for that helpful advice but today I took the Old Brake Pump apart, just to see what was in there and if it could be repaired

Which was a Nightmare to get open, as its got crushed in anti tamper rings presumably to stop you doing that

I'm going to do a full write up the next time that I update my 'Cherry Blossom Restoration' thread including Photos, so everyone can see whats inside

Keeping the Car Original is not really my thing, I just want to make it better where I can and since I have already got an XJS without ABS as well as some other XJS's that have

I can make a comparison between both of those systems and the one without the ABS is in my opinion a better Car to drive

After all they were using Brake Boosters in these Cars up until about 1987 so providing my Insurance Company is OK with it, then thats the way that I will probably go

 

OB, have you thought about having the motor rewound ( reconditioned)? If you are rewiring a new system it is best to go to the Electric manual and see how Jag wired the original system and then pencil in your modification and follow that.

 

Hi Afterburner

Wait till you see the Photos of what I found when I took that ABS Pump apart, which I wasn't intending to do, as there are anti tamper locking tabs to prevent you from doing just that

But as 'Warrjon' said it could be done then I had to do it rather than be a 'Snowflake' and wimp out

As for the Vacuum Servo or Brake Booster as I call it, there is No Wiring up to do apart from the Brake Light Switch

Which taken in the Scheme of things is a minor inconvenience to wire up, being no more than just a couple of wires

And that is just about it, apart from from having to modify the Brake Pipes which looks a very easy job as I've made all the Brake Pipes on my Cars

Then there is just the Vacuum Tube to connect to the Inlet manifold and maybe an Aux Vacuum Tank to give you more capacity if needed

Where apart from anything else I'd like to make that Mod, as from my own personal viewpoint I feel that it is Safer and less likely to go wrong

As I've had the ABS go bad on 3 occasions

Either through a Broken Wire in the Valve Block or one of those Valves getting blocked with rust or Crud, even though I change the Fluid every year

Where I have found myself Cruising along and then Suddenly and without Warning when I put on the Brakes

The Car took a Violent dive to the right and tried to ****** the Wheel out of my hand, where I felt very lucky not to be spun off the road

When the System was Brand New then no doubt it worked fine but 20 years of intense heat has made those wires go crispy, where maybe just a little jolt would be enough to break one

Or a build up of Crud in the Fluid could block up one of the Valves inside the Valve Block

Which doesn't tend to happen with a Vacuum Servo