Series III Brake Booster Option

Does anyone have any experience with this option?*14921|L2*15008|L3*15681

I’ve been driving my XJ6 daily for a few weeks as my normal daily driver is out of commission and today the brake booster failed (lost stopping power, obvious hissing from the booster plus a little groan from the booster when I press the brake pedal).

Thanks for any help.

the groan is usually a dry valve pedal side - where can you hear the hiss? as for a replacement, any reputable brand is ok just make sure it’s suitable for your model as there’s a difference in rod length & travel distance into the master cyl, some are adjustable most aren’t. the one you have post is listed as correct for your model, it’s up to you where you spend your money

Unfortunately, once I add the item to my cart to purchase, it shows up as “Out of Stock.” Back to the drawing board…

The old one can be rebuilt by a specialist, Matt - but a replacement should be available, and is the better option

xj6 85 Sov Europe (UK/NZ)

All the generic part sources I could find (Autozone, Advance, O’Reilly, PartsGeek, and others) showed that they sell the part, it is a direct fit, and it is out of stock with no indication of when it will be in stock again.

I’m paying extra to purchase from Welsh – doesn’t even appear to require a core return. I actually like the idea of having mine rebuilt, but I need the car back working properly ASAP. I can drive it in a pinch without a working brake booster, but I’m hoping I get the replacement before I have to think about that! Looks like a pretty straightforward job.

Driving without a working booster is, as you know, Matt, a work for Superman - not for ordinary humans without risk…:slight_smile:

xj6 85 Sov Europe (UK/NZ)

It’s a little tricky, actually.



I appreciate your reply! This gives me some context. I certainly will try to do this job without disturbing the pedal box, but your experience makes me prepared to give up after a smaller level of effort than if you hadn’t conveyed this. :slight_smile:

I’ll report back soon. I expect the booster to arrive tomorrow evening, so certainly by this weekend, although since I know it’s coming I might as well just pull the booster out now since that’s the hardest part.


As I looked at the job this evening and pondered my tool set (both in tools and personal ability), what struck me is that I don’t think I can get that cotter pin out of the booster pin. Given that and Doug’s description, I decided to do it the “proper” way and remove the pedal box.

I have a manual that simply says to remove the bolts from above the brake pedal (it said four but I found six) and then remove the master cylinder (disconnected from brake lines), booster, and pedal box all out as a unit. I still don’t plan to break the brake lines off the master cylinder and I have it disconnected from the booster. The pedal box now moves in the engine compartment but I’m not sure how easy it will be to simply take it out. I’ll have a few electrical connectors down at the brake pedal of course, but in theory if all those are disconnected, can the whole unit come out? Obviously if so, the brake pedal itself would come with it?


Worked on it again this morning. I got the booster/servo out without removing the pedal box. It was easier since I had to remove the master cylinder. As it turns out, the master cylinder is leaking out the rear. I think I’ll just rebuild it, that doesn’t look too difficult and a kit is pretty cheap.

As mentioned before, the booster is connected inside the pedal box with a fork and a dowel that runs through the booster fork, and that dowel is held on by a cotter pin. On my car, that cotter pin was on the fender side and it was not easy getting to the cotter pin in that tiny space. When I put it all back together, I’ll reverse the direction of the dowel and have it such that the cotter pin is on the engine side instead of the fender side.

Sadly it appears as if the master cylinder has been leaking for a while. I guess I just haven’t been watching carefully or ignoring it, but now I have surface rust from the corrosive brake fluid within the engine compartment. (See pics below).

Questions for those still reading:
I’m not creating a showcar. What would you recommend for mitigating the rust in the engine compartment caused by the brake fluid?

What about the gasket between the booster and the pedal box? Does anyone have a source?

This is the rebuild kit for the master cylinder. Seems pretty straightforward (I think I used those same words on my first post in this thread, though…).

Another option for a rebuild kit:

I’d buy from either – the prices are close enough – but I can’t find that gasket between the booster and the pedal box from either. If either sold it, I’d buy both parts from the same source.