Disk Brake Conversion

[derek]

I have the roam off road front and rears on my 88 and it was the best purchase I have ever done for my series. My wife was overwhelmed by the cost until she drove the truck. Now she enjoys driving it around town.

Just a couple of thoughts

1. Check your swivel balls, any pitting get prepared to replace them.
2. Replace all of your tie rod ends -

--- It is amazing what new swivel balls and tie rod ends will do. If I were to do it over again, I would have done the P38 power steering conversion at the same time.

Check out this link:http://www.expeditionlandrover.info/PowerSteering.htm

3. Check your axle breathers while you are down there.
4. Make sure your booster is in good shape
5. Check the rest of your brake lines for wear and movement.
6. Get ready to paint or powder coat all the parts that need it.
7. Replace the Races at the same time.
8. Replace your front shocks while you are at it (if they are original)
9. Swivel grease not oil in your swivel balls.
10. Get all your tires balanced and aligned perfectly.

[o2batsea]

Alternately you can use a hydroboost instead of the vacuum type. One will bolt up to a late s3 tower and plumb into a power steering pump. This will dramatically reduce the amount of body trimming, and give you a much lighter pedal.

[o2batsea]

There is nothing magical about a Land Rover brake booster. It's a pretty standard set up and you could probably fit something from the local pick and pull quite easily that'll fit on a S3/Defender tower. The only consideration would be the line fittings on the MC if you get one from say a pickup truck. The Rover ones are 3/8ths-24 which is not America standard. Easy enuf to make new lines with the proper ends.

[thixon]

There is nothing magical about a Land Rover brake booster. It's a pretty standard set up and you could probably fit something from the local pick and pull quite easily that'll fit on a S3/Defender tower. The only consideration would be the line fittings on the MC if you get one from say a pickup truck. The Rover ones are 3/8ths-24 which is not America standard. Easy enuf to make new lines with the proper ends.

Wouldn't you also have to be concerned with the bore and stroke of the master cyliner? If it can't move enough fluid to acuate the braking system, you'd be in for a wild ride!

[I Leak Oil]

To add to what Travis said, Mounting bolt pattern (on both ends), diameter, thickness, will you have to modify the fender to fit it, connection to the pedal....by the time you're done you're better off just getting a rover booster or find an alternate that you KNOW fits a series with minimal modification.

[o2batsea]

To add to what Travis said, Mounting bolt pattern (on both ends), diameter, thickness, will you have to modify the fender to fit it, connection to the pedal....by the time you're done you're better off just getting a rover booster or find an alternate that you KNOW fits a series with minimal modification.

They're all about the same. On both ends. Worst case you make a bolt plate out of 1/4 inch to adapt. But I know that a regular old Delphi MC is a straight up fit on an S3 tower, and if you add a hydroboost, the fender trimming is minimal. And I am pretty sure that your standard issue C-10 brake MC is well up to the chore, as well as anything similar. It's not like Rover used something that was not an off the shelf solution. Brake systems are more or less universal.

[luckyjoe]

Another less invasive option is to install 109 front brakes.

Surplus to my needs, I have a complete front set of 109 twin leading shoe brakes.

A nice upgrade for an 88...

[yorker]

Not sure how diaphragm diameter affects boost, as remote servo's are available in various boost ratios with the similar diaphragm diameter, or occasionally higher boost with smaller diaphragm (1.9:1 = 8", 2.3:1 = 6").

Maybe some have more than one diaphragm inside.

single:

Dual


Booster style Pedal PSI out Maximum Attainable

7” single diaphragm 120 800 800
7” dual diaphragm 120 900 1200
8” dual diaphragm 120 1000 1400
9” single diaphragm 120 900 1200
9' dual diaphragm 120 1200 1500

The efffect of booster size on pressure
output.
The effectiveness of your braking
will ultimately be determined by the
amount of hydraulic pressure being
pushed out to the wheels. The primary
factor is how much power assist your
booster will provide.
As a general rule the pressure
output of a booster is directly proportional
to it’s diameter, the bigger the booster
the more assist it will give. Other factors
will enter into the equation such as vacuum
level or booster design. Low vacuum
will diminish your boosters assist. anything
lower than 18” will begin to diminish
the performance of your booster so it’s
necessary that you have at least 18” of
vacuum from your engine. The smaller
the booster diameter the greater the negative
effect of low vacuum will have on
the booster. NEVER GO BELOW 16”!
Booster performance can be
enhanced by modifying the design. By
adding an additional internal diaphragm
you can generate additional assist giving
you the performance of a larger booster
in a smaller space.

http://www.mpbrakes.com/uploads/documents/optomize.pdf

also:

The effect of master cylinder bore
size on pressure output.
By changing the bore size of
the master cylinder you can adjust the
amount of pressure output. The smaller
the bore of the master the more pressure
it puts out. The trade off is pedal travel.
too small a bore will stop you nicely but
you may be very uncomfortable with the
travel. The following data is with 20”
vacuum and a dual diaphragm 8”
booster.
So typically you can gain a 25%
increase in pressure output by dropping
to a 1” bore master from 1-1/8”

see also: http://www.classicperform.com/PDFs/B...ssureChart.pdf

This is the formula to figure your output booster pressure.

Force in pounds = (Diaphragm area in square inches) x (manifold vacuum in inches Hg) x ½

Example: 7” single diaphragm booster with 17 inches of vacuum. 3.5” x 3.5” x 3.14 = 38.465 square inches x 17 inches of vacuum x 50% = 326.95 psi

Power Boosters: Power boosters were needed when disc brake systems were being used more and more on factory cars. The amount of boost created from the booster is directly related to the square inches of the booster and the inches of vacuum imputed from the engine. Since the disc brake calipers required a greater volume of fluid due to the size of the pistons and the clamping force (some times up to 6 tons), the master cylinder requires a bigger diameter bores to push the required volume of brake fluid. When you increase the bore size you reduce the output pressure of the master cylinder. In order to boost the pressure output of this larger bore master cylinder the factories installed a power booster. Power booster range in size from 7" to 11". Most street rods have floor mounted pedals so the master cylinders are generally located under the floor boards. This creates a room problem so the 7" booster was incorporated to use with the 1" and 1-1/8" master cylinders. The biggest problem with using a power booster is it requires vacuum to operate and most hot rods have 3/4 race cams so there is little or no vacuum. If you are currently using a power booster and having problems stopping, take a vacuum gauge and check the inches of vacuum. To work properly it takes 16-18 inches of vacuum anything much less than this forget it.

The dual diaphragm 7” has a total area of over 76 square inches about the same as a 10” single. This doubles the vacuum assist of the single diaphragm. I would recommend anyone using the older single diaphragm to update to this booster.

http://www.hotrodheaven.com/tech/brakes/

[TeriAnn]

Nice bit of research very well presented.

[Apis Mellifera]

I've been pondering disc brakes for a while. Does anyone have a spare front swivel housing etc? Basically everything from the swivel ball out. I have access to 3D scanning, rapid prototyping, 5-axis CNC, etc. It seems like most people could source common calipers and brackets and rotors, if off-the-shelf. What is not so easy, is sticking the pieces on stock parts. I'm not saying I can definitely do this easier and cheaper, but I have some ideas I'd like to flesh out.

[Revtor]

You could maybe go here and pull a few.. Oh wait that's the Defender pile...

http://www.4x4dergi.com/hurda-arac-israfi/

ouch!
~Steve

[jp-]

I am working on a Disc brake conversion, using off the shelf Mazda parts. You get to keep your Land Rover hubs, and it works with stock 16" wheels. Testing hopefully to be completed early next year.