Has anyone converted series 2 or 3 XJ brakes to HydroBoost? Pictures? Known conversion kits?
Thanks,
Clyde

 

I don't get it. Hydro denotes hydraulic to me. Boost denotes assist.
Our jaguars like most "modern" cars have hydraulic brakes. and most are boosted via engine vacum.

Way back when, Tbirds used hydraulic brakes, but with a hydraulic booster in lieu of a vacum boost.

The hydraulic cylinders actuate the brake calipers, while the vacum bellows assist in applying the pedal to the master cylinderr.

But, you might well have something entirely different in mind.

Nomenclature can be confusing.

Carl

 

HydroBoost systems were used on a lot of heavy-duty and Diesel pickups in the US beginning in the 1970s; some of the big Lincolns used it before they were downsized. It was powered by the power steering pump rather than engine vacuum.
I don't understand why you would want to do this to a Jaguar. Perhaps because it is fairly compact when compared to a vacuum booster; I don't know.

 

Compact is the issue. More so for trying to update the brakes on the Mark 2 I purchased, but also for more stopping power on XJ12L/BBC
Regards,
Clyde Gantz

 

HydroBoost from what I read is a Bosch Trade name. I had Hydro Boost on my 1985 Buick Grand National.

 

I have found the factory vacuum booster more than adequite and I only manage about 14 inches of vacuum with my setup. If you're not making that much vacuum try a eletric vacuum pump. Hydroboost brakes are clumzy, leaky and a plumbing nightmare. Hydroboost is great when you dont have room for a vacuum booster in the engine compartment. Other than that a eletric or mechanical vacuum pump is the way to go.

I have mentioned this before...but the rear brakes are just along for the ride and dont do much becasue the system, as designed, is heavily biased to toward the front. This is done with calipers and piston sizes and there is no proportion valve to tweek for better balance. If you simply increased assist using hydroboost or some other method the bias would be the same and you would still have poor brakes becasue the front would lock and the momentum of the car would overcome the front wheels ground friction. This is what to do becasue this is exactly what Aston Martin did with the DB7 and what Jaguar did with the later XJS...they left the front rotors and calipers the same and simply upgraded the rear calipers and rotors.

There are many ways to get these cars to stop better. If you upgrade your rear brakes and actually have them do some brake work the car will stop signifigantly better. An increase in rear bias must accompany a increase in rear tire adhesion to maintain balance and with a BBC you're gonna need larger rear tires anyway. Relocate the batter to the trunk while you're at it. Doing these things will also decrease nose dive and give the vehicle much better dynanics.

Over the years I've tried various things and stuff like upgrading to better pads and drilled rotors can only get you so far.

Also see this thread....
https://www.jaguarforums.com/forum/x...94/#post769581

You do nice work and I can only imagine that your detailing of this setup would look amazing.

 

Icamerica,
Thanks for the link. Great read, which I will re-read. Lot to absorb first round. Thanks for sticking with me on the understanding of the bias. A lot has been spent on the stock set up to date, so I'm likely to live with it for now. If it is so out of hand to stop, I have to consider changes to the rear as indicated in the link.

 

Hydroboost is hands down the best power brake setup I've ever used. If the booster and your pump are working properly, you will eat your steering wheel. Assuming of course proper traction and the rest of your braking system is good. As far as plumbing, you need 2 hugh pressure hoses and 2 returns. The high pressure can be made out of SS braided teflon -6. The reservoir should have 2 return bungs as well, a 2nd one can be welded or brazed on to your existing can, otherwise get a rebuilt pump for an 80s diesel suburban. If it leaks, well you're doing it wrong.

I've got a BBC series 1 that I'll convert to hydroboost in the next 2 weeks. I've also worked on another S1 project that I've helped convert to hydroboost. Made adapter plate between stock aluminum pedal mount and booster, modified the rod length, and used late model GM aluminum master with plastic snap in reservoir like from an Astro Van or silverado truck and Wilwood manual adjustable proportioning valve. Tricky part is the reservoir and hood clearance. Used remote reservoir and machined some low profile pieces that snap into the place of the stock reservoir. This one is still a work in progress, so I can't speak for its performance, but I'm confident it will be as good as the 5 or so other cars and trucks I've put hydroboost on. Bleeding the P/S hydraulic system correctly is a must on new systems, otherwise it will moan and groan and you'll have bad steering and bad brakes.

 

Wow, that LS is tucked back far. That's going to be great for handling and balance. I like they way the driver side exhaust goes forward and crosses over the front, nice work, and it eliminates the steering shaft issue. This project is going to be ridiculously powerful. Good info on the hydroboost and I love that remote brake fluid tank, it's reminiscent of the original design.

 

Thanks for the compliments. Yes, it should be a fun daily driver. Lots of work done, trans tunnel, firewall , rear inner fenders slightly tubbed to fit 275/40-17. Down to wiring and interior work. Car belongs to the owner of the shop I work at Sire Custom Performance in Los Angeles.

 

GM style Hydroboost is without a doubt the best hydraulic brake system EVER!

i have had them on many vehicles, 2 suburbans, 1 chevy silverado truck, 1986 buick GN, over 200K miles,never a problem!

small (compared to vac booster), and latetly some guys are using an electric P/S pumps, instead of belt drive pump, even to run the P/Steering, pump
can be mounted almost anywhere!

today i would deffinatly use a Hydroboost system, for my XJS, i have race cams and vacuum is barely able to function properly,(had to add an electric vac pump when im idling in traffic!