[Saloon-lovers] MKVII Disc Brake Conversion

Saloons
1

The following is a list of Parts, Part Numbers and Prices of all the pieces
that I used to convert my MKVII to Four Wheel Disc.

Left Front Caliper CarQuest # 18-4081 $28.08
Right Front Caliper CarQuest # 18-4082 $28.00

Front Brake Pads CarQuest # BD 52 $20.63
Front Caliper Bolt Set CarQuest # H5004 $12.08 X2 $24.16
Front Brake Hoses CarQuest # SP296 $22.25 X2 $44.50

Left Rear Caliper CarQuest # 18-4116 $93.61(has cable
emer. brake)
Right Rear Caliper CarQuest # 18-4117 $93.61(has cable
emer. brake)
Rear Brake Pads CarQuest # RD 122 $13.96
Rear Caliper Bolts CarQuest # H 5011 $6.82 X2
$13.64
Rear Brake Hoses CarQuest # SP 296 $22.25 X2 $44.50
Left Rear Parking Lever GM # 1800-3044 $ Lost Receipt
Right Rear Parking Lever GM # 1800-3045 $ Lost Receipt

11" Vented Disc Rotors CarQuest # 5512BDR $76.41 ea X4 $305.64

Body to R Axle Brake Hose CarQuest # SP 6293 $29.34

Next Three Parts Purchased From: Master Power Brakes (704) 664-8866
Mooresville, N.C.
www.mpbrakes.com

Remote Master Cylinder-GM Type-1" Bore-Dual Chamber # MC 1001 PZ $139.95
2# Residual Valves (needed between M/C and rear calipers) # VL 3702 $26.00
each
Hydralic Brake Light Switch #
HW 2003 $19.95

Other Related & Misc. Parts

Rear Axle Inner Seal CarQuest # 42763 $14.48 each
Rear Axle Outer Seal CarQuest # 440085 $ 8.27 each
Rear Axle Bearing CarQuest # 25877 $13.52 each
Rear Axle Race CarQuest # 25820 $ 8.42 each

Front Inner Race CarQuest # 14276 $ 5.09 each
Front Inner Bearing CarQuest # 14138A $15.10 each
Front Outer Race CarQuest # 09195 $ 4.58 each
Front Outer Bearing CarQuest # 09067 $ 9.78 each

This is by no means a simple conversion, it involves some machining and
some serious fabrication. The Caliper Mounts have to be made from scratch
from plate steel. A mount to bolt the GM Master Cylinder in place of the
original has to be fabricated and also a plunger pin. The Rotors have to be
machined somewhat,
the center hole has to be opened up to a 3.875" ID and the 5 stud holes have
to be counterbored from the rear 1/8" deep to a .625 ID.
I have patterns for the caliper mounts and am trying to get prints drawn.
The biggest problem I had was the fact that the calipers are rather bulky
and I had to machine some of the body away to have enough clearance to keep
them from rubbing the wheels. It’s not as big a deal as it might sound, it’s
just a matter of sanding some of the housing away which is quite thick. All
of the CarQuest Brake parts were original equipment on 1969 thru 1978
Cadillac Eldorado and Oldsmobile Toronado and also some Buicks of the same
era. There may well be another caliper that will work that is not so bulky.

There are several ways to approach this conversion and this is just what I
was able to get to work. I drove the car for a couple of thousand mile and
never had any problems, but I have since disassembled the car for a
“frame-up” rebuild. I can assure you that the car would “stand on it’s
nose” when you wanted it to.
As many of you know the original hydralic system is a single chamber
system. There is not a separate circuit for the front and rear brakes as on
more modern cars.
If you blow a seal or a line you lose all brakes. It may be possible to use
the rotors and calipers I have listed with the original system if the fluid
displacement of the original master cylinder is adequate but even though you
will have disc brakes, you
will still have a “single circuit” system.
I will be happy to try to help anyone that wants to attempt this
modification is you will contact me “direct”. I want it understood that
this is not something you can do
in your garage some Saturday with a few hand tools!!
I hope this information will be of use to some of my fellow Jag-Lovers.

Regards

Ken Nicks (tr302@aol.com)

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1 Like
2

I’m curious about the master cylinder… I agree that to drive with a
single chamber clyinder is not a good idea. I want to add just the dual
circuit master cylinder. Was this a non-boosted cylinder? my mk 9 has
a booster that i assume will work. also, since the mk9 has 4 wheel
disc, the residual value between the front and rear brakes will nto be
neded…correct.

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3

John,
The dual master cylinder that I used is basically a shelf item. The
biggest problem that I have found with the Jaguar system is the fact that it
is a single circuit and the
booster is remote from the master cylinder. With our original systems the
brake fluid pressure is boosted after it leaves the master cylinder and
therefore is boosting the “single circuit”.
In modern automobiles the dual circuit master cylinder is bolted to the
front of a booster which means that both circuits are “Boosted”. A “Booster”
is a single function unit also and that is why all the dual systems that I
know of are bolted to the booster.
I was unable to find a booster/master cylinder that would fit in the very
limited space provided by our “thru the floor pedal system”. If you were to
install a dual
cylinder you would not be able to boost both circuits. I had boosted front
brakes and unboosted rear brakes. That is fairly common in “street rods”.
My car had been parked for eight years and the reason it was parked was
because the brake system was inoperative. The booster was busted and all
the rest of the system was rusted internally. I drug the car onto my
trailer with a winch because the brakes were frozen. I didn’t have much
choice since I had Junk “shoe brakes” and even the steel brake lines had to
be replaced.
Since my car has been totally disassembled I have changed from the floor
pedals
to a swinging pedal which incorporated an 8" booster that mounts to the fire
wall and has a dual master cylinder attached. That is a major undertaking
that involves a good bit of fabrication and work under the dash, not
something I would recommend
unless someone is involved in a “frame up” rework.
My best advice for anyone with a single circuit brake system such as your
MKIX would be to always have a full unopened can of brake fluid in the boot
along with a
pair of “vise grips”. If you blow a cylinder or a line to one of the four
wheels or the front or rear lines you can always use the vise grips to clamp
off the rupture and limp home with 2 or 3 wheel brakes.
I guess I have rambled a bit but I hope some of this info will be of use
to someone
contemplating a brake project!

Regards,

Ken Nicks (tr302@aol.com)
'51 MKVII

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4

Ken Nicks wrote:

In modern automobiles the dual circuit master cylinder is bolted to the
front of a booster which means that both circuits are “Boosted”. A “Booster”
is a single function unit also and that is why all the dual systems that I
know of are bolted to the booster.

Hello Ken,

The 420 and the later "E" type have dual circuit brake system with a

remote dual circuit booster. The master cylinder has the air valve mounted
to it. I do not have any experience with it, but I know the parts are
expensive and I’ve heard it’s not the best dual circuit system. I am using a
single circuit booster from PBR that works great, but next time around, I’d
go for twin Tilton masters and a remote PBR booster. Just one opinion.

Paul Saltwick
3.8S Type

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5

Paul,
Thanks for the information, I am not familiar with the 420 and later “E”
type dual systems. A dual booster was what I started out looking for but I
hit a Dead End.
That’s when I gave up and went with a “split” system. None of the brake
people that I talked to knew of a dual booster.
If you have some info on twin “Tilton” masters, please share it!! If I
had a MKIX like John Shuck and was concerned with having a single circuit
system, a twin
master that would work with a remote booster would warrant some serious
investigation.
I ended up with a “Midland” booster from Master Power Brakes and was
pleased with its performance. What or Who does PBR stand for?
I guess some people find some of the discussions that are on the “site”
boring but IMHO it’s a wonderful way to share information and ideas.

Regards!

Ken Nicks

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6

Ken wrote:

If you have some info on twin “Tilton” masters, please share it!! If I
had a MKIX like John Shuck and was concerned with having a single circuit
system, a twin master that would work with a remote booster would warrant
some serious investigation.
I ended up with a “Midland” booster from Master Power Brakes and was
pleased with its performance. What or Who does PBR stand for?

Hello Ken,

Tilton makes several sized single cylinders available at most of the

racing supply shops, for a dual set-up, you mount two side by side. PBR is
an Australian brake manufacture and Terry’s Jaguar Parts sells their boosters
as “replacements” for Mark II/ S Types. There is nothing like “new” parts
and they work well, but you’re on your own mounting it. My guess is that
product liability in this country makes aftermarket brake parts a very risky
business. Some European cars actually used dual masters and two separate
single boosters under the hood for dual circuit brakes. The booster behind
the master is a great idea, unfortunately for many saloons, it’s major
surgery.

Paul Saltwick
3.8 S Type

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7

Has anybody fitted a dual circuit to the S-Type in any way?, without using
420 subframe etc, something simpler, a bolt on master cylinder and a few
extra pipes?

Alastair Lauener
64 S-Type
@Alastair_Lauener

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8

Alastair,
I know absolutely nothing about the layout of the brake system on the
S-type or
420. I do know that there is a Four Wheel Disc Master Cylinder listed in
the catalog
of Master Power Brakes that is a Manual model and has a longer stroke than
others.
They list it as Part# MC390360M4 ar $119.95 each. It is not a remote fill
so an access panel would have to be cut in the floor of a car like mine
(MKVII) to check and fill! They also list a boosted cylinder and even sell
a stainless access door!
There website is www.mpbrakes.com and click on the heading for Street Rod
Accessories.
I have no affilation with these guys but they are one of the largest
suppliers of any
type of aftermarket brake components in the US. I have found them to be
quite helpful and knowledgable. There facility is only about a 35 min.
drive from my business. If I can be of assistance let me know!
I would suggest that anyone with any brake project in mind log on their
site and check them out.

Regards,

Ken Nicks (tr302@aol.com)
'51 MKVII

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9

Yes this is been most helpful I recently purchased a mark seven that was put away 10 years ago that Bad master cylinder rebuilt master cylinder all four wheel cylinders have no pedal whatsoever. Wondering if I can used said alternative master cylinder and bypass Break servo and just use a newer master cylinder? Anyone knowing any more topics on dealing with the brakes I don’t 1956 Mark seven would be helpful Glad I found this forum it’s torture not be able to drive a new car because of breaks

10

It isn’t really a big deal to rebuild the hydraulics. You might have to get the wheel cyls sleeved, and possibly change to a more modern remote servo.

11

Can you suggest any remote servos
And or break masters

12

I’m not very familiar with the MKVII, but I’m guessing that any 7" remote servo such as the MGB etc would do - you can get them in various ratios, perhaps someone knows what ratio the car was originally fitted with, and if going up a size is worth it or not.

On the master, you can either rebuild it (have it sleeved if the bore is pitted), or you can find one with the same mounting, stroke, and diameter, and use that.

13

I’ve been following these threads and looking endlessly as well. I’d love to install a dual circuit MC in my Mk2 even if I had to dump the booster and run manual brakes.

Wilwood makes generic MC’s and has options with remote reservoirs but I’ve never seen one adapted to a saloon. If I understand what’s said above, is it that the way the pedal swings and pushes the rod is not compatible with these generic MC’s?

14

Keep in mind that as I recall the Rover 2000TC circa 1969 used two boosters, one for the front brakes and one for the rears. Both boosters were mounted on the inner fender RH side under the hood. I suspect this was a work around before a suitable dual master cylinder/booster combination was available.

John F. Quilter
Eugene, Oregon USA

15

And I just found a photo on Google Images of this set up in case anyone is interested

BTW how do you attach photos to the new Jag-Lovers forums postings, if that can be done.

John F. Quilter.

16

John,

Guides are all in User Guides and How-Tos, you the one on uploading pictures is:
https://forums.jag-lovers.com/t/how-do-i-add-pictures-to-a-post/349356/4

17

Rover 2000TC engine bay.jpeg738Ă—415 71.9 KB

Testing the photo upload feature with the mentioned Rover 2000TC dual brake booster system.

John F. Quilter
Eugene, Oregon USA

18

Thanks for that excellent info, great post.

out of left field, wonder how easy to use a rear end (and brake system) from a more common vehicle to modify and swap in, often done with older off-road vehicles, plenty from '70s & 80s had rear leaf & discs.
even keep same ratios with Dana

The Oz made PBR universal boosters are made specially to replace older models and are very good