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Disc Brake Conversion Questions

10K views 26 replies 13 participants last post by  bacook 
#1 ·
So, I have a '76 Series 3 ex-MOD 109 that has a 3.5 liter V8 from a '88 RRC installed. I despise the drum brakes that are on there. I want to convert them to Disc brakes and I plan on using the kit from Heystee Automotive. I am confused though about the servo and master cylinder. Heystee seems to indicate that to do a 4 wheel disc conversion that I have to install a pedal box, servo, and master cylinder from a Defender. But it also seems like I have seen elsewhere on the web that it's ok to install the 4 wheel discs and keep the series 3 pedal box, servo and master cylinder. Being a '76 it already has the dual circuit master cylinder so it seems that this would be ok with the discs. Anyone here done the Heystee conversion?
 
#3 ·
Call Forbyn Brothers for a better outcome. Here's a pic of my 1976 Series III 109 with their disc brakes installed:
 

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#6 · (Edited)
I'm installing a Heystee conversion on my SIIA 88" - using D-90/Discovery solid rotors on the front and staying with 10" drums on the back. I've got a Series III pedal stand and bought the booster from Heystee because its smaller in diameter than the later Land Rover units and won't require as much fender cutting. I'm planning on using the master cylinder that was used on the disc/drum equipped 110's. I also switched to later wheel cyinders in the rear brakes so all the brake pipe threads in the system will be metric instead of a mix.

Couple of gotchas with the Heystee conversion if you're not expecting them - not a big problem but for information purposes so you aren't surprised by them:

Clearance around the 12 mm star head bolts used to mount the front calipers is very tight. Be prepared to turn a box head wrench by 1/8 turn before re positioning the wrench for another bite. Also you might need to do a little clearance grinding where the caliper bolts up to the new swivel housing - its best if you do this on the bench before you have the hubs and rotors mounted (I didn't).

Your Series III master cylinder will not work on disc brakes because the front chamber of the drum brake M/C does not have enough volume to operate the calipers.

Also the new hubs are supplied with the larger studs that were introduced on the Series III - which means you have to find a set of stock Series III hubs for the rear axle if you're upgrading a Series II (unless you don't care that the rear axle will take a different size lug nut than the front axle).
 
#7 ·
My series 3 is a '76. I've ordered the front and rear conversion from Heystee along with the 8" servo and plan on using the same 110 master cylinder as you. I also think I might replace all the brake lines so everything is metric. So basically I have a completely new brake system except for the pedal box. Thanks for the tips!
 
#11 ·
I was doing some research tonight and found that the 1987 Range Rover uses a Lockheed master cylinder that looks like it would fit the early Defender servo as well as the Series 3 servo. Part number is RTC3658. This might be a better option than the early Defender 110 master cylinder since it was designed for front and rear disc brakes. Any thoughts?
 
#21 ·
WRONG!

Paul Heystee first used Santana disc brake parts for his conversion totally unaware of Timm's efforts. It is anyone's guess as to who started development first. Timm likes to say his design was ripped off but it is not the case. I've known both parties for decades and both developed their systems in the same time frame independent of one another.

When the Santana brake parts started to become hard to get, Paul modified the Santana design to use Defender type rotors and calipers. Since form follows function and both parties used Defender parts the products do look similar. Timms design used a single casting for both sides and machined the R & L sides differently. Paul's design used a different casting for each side. Since Paul's castings are handed they do not include attachment bosses on both sides making it the lighter weight steel swivel housing.

There was no rip off. Just independent development in the same time frame with form following function.
 
#14 ·
Hey guys, I am in the process of swapping in my haystee kit now. I need one of these gaskets though. What are they called specifically, does anyone know where I can get one?

All I bought are the kits from haystee and the defender stuff. I just have the stock maser cylinder in there, where should I go for the new one that I am reading I will need?

Thanks and please


 
#16 · (Edited)
I think I had the 2nd prototype disc conversion that BCB (Timm Cooper) made and used the standard dual servo master & servo used on my 71 11A... it worked really well stopping my 300hp Chevy V8... Just did a conversion recently on a 78 109 using RRC axles and brakes & still kept the stock Servo & master (new one) worked out well.

------ Follow up post added August 16th, 2017 01:45 PM ------

PM me:) I am local and have done this conversion.. (the real one)

Hey guys, I am in the process of swapping in my haystee kit now. I need one of these gaskets though. What are they called specifically, does anyone know where I can get one?

All I bought are the kits from haystee and the defender stuff. I just have the stock maser cylinder in there, where should I go for the new one that I am reading I will need?

Thanks and please


View attachment 282202
 
#15 ·
That is the swivel ball seal. Sold everywhere, but avoid Britparts unless you want a leak. To replace it properly, you will need several other gaskets as the hub and housing have to be removed (as you have done in your picture).

There is another way where you use a fine blade to cut the seal at the top, carefully slide it over the swivel ball, and then seal the cut at the top of the axle, but I'd do it the correct way.

Rovers North sells them as do most others.
 
#19 ·
Awesome! Thank you.

Also what is this pin or clip that holds these together? I can't find anything on line and they didn't come with the caliper kit... any ideas guys?

View attachment 282418
We have piles of the brake hardware, but need some more defined pictures to guide you or send what you need.
 
#23 ·
Since there has been some discussion about the servos I thought I might add a little.

There were 2 different Series III servos, though both looked the same. Both have a 6 inch diaphragm. LR1781 (STC1816) used on the 88 has a boost ratio of 1.90:1. The 109 used LR15248 which has a boost ratio of 2:1. I have no idea what the aftermarket servos have.

When Santana went to disc brakes they used a servo with an 8 inch diaphragm to get more boost. Since Santana used the same pedestal as the SIII Land Rover the Santana servo is a direct bolt on to a Series truck.

The Defender uses a different servo attachment than the Series, which means you cannot mate an unmodified Series pedal to a Defender servo. The early Defender servo was an 9 inch type 50. To get it to work on a Series pedestal you would need to either modify the end of the pedal or narrow the end of the servo rod.

The later Defender type 80 uses an 11 inch diaphragm for even more braking boost. The type 80 will not fit under a standard Series bonnet without playing some cut and weld games with the pedestal. The Series Deluxe bonnet is taller and will fit the type 80 vertically. However the wing top would need to be cut out to the edge of the bonnet and the bonnet flange removed or bend up at the side of the servo to get a fit.

I have not looked at Disco or RRC servos for fit but assume they use the same servo rod end as the Defender.
 
#24 ·
You can also modify a series or Defender pedal box to accept a GM style Universal brake booster. You then cut the GM rod down and use the cleavis from the Land Rover booster after Drilling and threading it.

I have a dual 11 inch GM truck style booster on my Defender now and it works amazing. The issue with the series trucks not having enough room for the larger diameter booster could be avoided if you modified the series pedal box to use the GM Style Universal brake booster and get a dual 8 or dual 9. Both of these are smaller external diameter but have considerable increase in booster volume over the single diaphragm units.

I have this explained in my salisbury disc brake conversion thread.

The GM style brake boosters will also accept the Land Rover Masters with just very minor grinding of the Land rover Master holes to make them slightly wider
 
#27 ·
This is the combination of parts I went with. I'm making all of the brake lines, so I can't confirm that they will line up with the hoses and pipes in an existing system, but they fit the Heystee kit.

Brake master: NRC8690
Front Calipers: SEB500460, SEB500470 (from 6A713928, after 1984)
Front Rotors: FTC902
Rear Calipers: STC1268, STC1269 (to 1A614447, to 2001)
Rear Rotors: FTC3846G (to W159806, 1998)
 
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