Author Topic: MK3 Wheel Cylinder seal Kit's  (Read 2178 times)

Offline Karl

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MK3 Wheel Cylinder seal Kit's
« on: October 17, 2017, 08:50:22 PM »
Hi All,

I have a MK3 I recently found on a farm near Parkes, NSW. It had been abandoned for years.

Didn't take long to get running & it is now going well. It now has an ex-RFS 3600litre gal tank & twin reels.

The brakes are working, but leak slowly when parked. I figure that the bores wheel cylinder bores must be in decent shape,  so probably only need new seals.

My question is to where can I procure such items as I have been not having much luck in doing so??

Thanks Karl

Offline Mick_Marsh

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Re: MK3 Wheel Cylinder seal Kit's
« Reply #1 on: October 17, 2017, 09:54:30 PM »
I just took mine down to a brake shop that deals with trucks.
ABS was the one. "Please fix these." I asked. They did.
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Offline Ravvin

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Re: MK3 Wheel Cylinder seal Kit's
« Reply #2 on: October 18, 2017, 08:31:38 AM »
The 2 rubber seals in the rear brake slave units are PBR P621.
The big rubber boots that cover the back of the slave cylinder are Girling 363521 and I got a pack of 4 from the UK really cheaply. I will look up the seller's details when I get home tonight.
I can't find where I wrote down the number for the seals in the front brake slaves. The guys here just matched them by size with standard PBR or compatible parts for $5 each. I thought I mentioned the number in my rebuild thread but can't find it.
I'll check my notes tonight when I get home.

Greg.

Edit: Just checked back through my posts and the big rubber boots over the rear brake slaves is sold by http://www.northwestclassic.co.uk/



I can't find the number for the rubber seals for the front brakes, but the guys just matched them and said it was a common part that they always had in stock.
« Last Edit: October 18, 2017, 09:42:38 PM by Ravvin »

Offline Karl

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Re: MK3 Wheel Cylinder seal Kit's
« Reply #3 on: December 21, 2017, 06:19:35 PM »
Thanks for the Replies.

I ended up taking them to ACT Brake's in Mitchell, as when I disassembled them they were corroded worse then I expected.

They have done a few sets for Inter Mk 3's & 4's

Offline Chazza

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Re: MK3 Wheel Cylinder seal Kit's
« Reply #4 on: December 22, 2017, 09:12:23 AM »
Nice to have you on the forum Karl!

Please post heaps about your truck,

Cheers Charlie
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S2A 109" GS '63
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Offline Andrew L

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Re: MK3 Wheel Cylinder seal Kit's
« Reply #5 on: February 24, 2018, 12:14:06 PM »
Ravvin,
any luck finding the number for the seals in the front brake slaves on a Mark3 ?
 I have one weeping

Offline Ravvin

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Re: MK3 Wheel Cylinder seal Kit's
« Reply #6 on: February 24, 2018, 04:40:59 PM »
I searched all my receipts but couldn't find what the local place had them listed as.
Luckily, your post reminded me about this and I went back through the parts manuals to find any info I could.
The original part was made by Girling and was listed as 362300. I used the NSN number and found that an alternate part number was P4189.
A quick search and I found an actual eBay listing that listed the P4189 number and when I zoomed in on the pic, I saw that the boxes also had 362300 on them.

Anyway, you can go to Repco and see if they still list them as the P4189 number, or can find a cross-referenced number. They are described as a 1" seal, 1/2" thick.
Or, if you can wait a week or so, I'll send you a pair from the lot of 27 that I just bought :)



Greg.


Offline Andrew L

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Re: MK3 Wheel Cylinder seal Kit's
« Reply #7 on: February 25, 2018, 02:24:08 PM »
sent you a message Ravvin

Offline Ravvin

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Re: MK3 Wheel Cylinder seal Kit's
« Reply #8 on: February 25, 2018, 07:46:19 PM »
Got that, and replied.
While you are playing with the brakes, I suggest you check the master cylinder/air actuator too.
All of mine had leaked between the air actuator and the brake master.
It's an easy job. You will probably want to run new Dot 4 brake fluid too. The deck of my truck was rotten, so I was able to rip out enough wood to get my arm in to get a spanner onto the 3 nuts that hold the mounting bracket to the chassis rail. You probably can't do that, so leave it bolted up and follow the instructions below.

Drop the air pipe and the brake fluid pipe. Run around madly looking for a tin to catch the old dirty brake fluid that is running all over your shed floor.
Get back with the tin just as the last of the fluid runs out.
Loosen the 2 bolts that hold the metal band closed that clamps the 2 halves of the air actuator together. Be ready. It will try to pop open as the band loosens. The spring under the big piston that the diaphragm presses against is not super strong, but right-handers will struggle to hold it in with their right while undoing the clamp bolts with their left, as you will probably need to use both hands as the nuts usually turn too.

(As a note, the original bolt heads are some weird torx type thing, but I recall a 10mm socket could be flogged on and worked well. I replaced all mine with high tensile socket head bolts and nyloc nuts).



With the spring tension off, check the diaphragm for cracks or splits and pull the piston and spring out. One of mine had wet brake fluid coming through the hole around the piston shaft. Both of my trucks had sat for a long time before being moved, so if yours has been run occasionally, it may be ok.
Next, undo the 2 nuts that hold the air piston chamber to the alloy mounting bracket. One of the nuts has the stroke indicator poking through it. Poke it in and remove it or it will fall out and get lost.
With the nuts off, you can slide the diaphragm chamber off and look inside for corrosion. One of mine had leaked into here a long time back and the recess was almost totally filled with while powder from the brake fluid reacting with the aluminium.



Next, remove the 3 nuts that hold the master cylinder to the mounting bracket. 2 small and one larger. No idea why. With those undone, you can tap the whole master cylinder out and give it an overhaul.

This is pretty easy too.
Undo the filler bung on top. Be gentle on it as it has a tiny breather hole in one of the flats and if you smear the soft alloy over it, you will have vacuum issues later.
Drain any brake fluid out. Remove all the slot-headeed screws and take the top cover off. Try not to damage the celuloid-looking gasket if you can help it. The one on my MK3 was stuffed as it stuck to the alloy housing and lid and separated when I pried them apart. I made a new one out of thick gasket paper smothered in Aviation Forma-Gasket #3 or #5. Can't recall. One is fuel and brake fluid safe. It sets hard, so you will have to make another if you ever open it again. Clean any crud out of the reservoir. The 2 on my F1 were pretty clean but the one on the old MK3 was interesting.



With the reservoir wiped out, stand the master cylinder on it's end, with the bolt holes up. Use the air actuator piston to push the brake piston down, but try not to hit the bottom if you can help it or you may damage the drain-back valve.
Now clean up all the brake fluid that squirted out, usually straight onto your shorts where it will run down your leg and soak into your socks.
From here, you can push the piston down a bit and use circlip pliers to remove the inside circlip that stops the piston popping out. Number 9 on the pic below, far right of the string of piston bits if you can't see the numbers.
(Note. Get yourself a good quality set of inside and outside circlip pliers. Preferably, get a straight set and a bent leg set. Cheap is just not worth the frustration when they slip, bend or snap the tips off, usually late on a Saturday or Sunday just after the shops shut).



You may be lucky and find your circlip still has both eyelets on the ends. One on my F1 was missing and the MK3 had a different curly shaped retainer ring that was a real pain to get out as the recess was packed with corrosion and crud..
Once its out, you may be lucky and the piston will pop out as you take the pressure off the piston. If not, it is usually because there is a ring of glazed, dried brake fluid and stuff on the cylinder wall below the circlip. I suggest you push the piston down and carefully remove the build-up with fine wet & dry dipped in turps or diesel. You can also wipe a bit of vaseline or rubber grease around the bore and see if it will pop out then.
If that fails, remove the banjo bolt from the end of the cylinder, stick an air nozzle in and give it a puff. Now clean up all the brake fluid that squirted back out of the passages into the reservoir and up the wall. Hopefully you have safety glasses on. Now go and try to find the piston, seals, spring and drain-back valve which shot out and rolled under the bench to the back wall or to the exact centre under a nearby parked vehicle.
Of course, you can avoid all this fun if you wrap the whole thing in a rag before popping it out.

Clean everything up and check the bore. All mine were really good. I gave them a light touch with a fine hone, then wrapped the hone in fine wet & dry dipped in turps for a bit of a polish. Go slow and keep it wet.
The PBR rebuild kit is still available. Ask for part number K3X. They cost me about $60 each, but it has the 2 new seals, new spring and drain-back valve. It also has a thing like a thick rubber washer. This is important. It goes into the bore before the drain-back valve and stops it smacking against the back wall. Also, make sure the old one comes out when you disassemble the unit. It's easy to miss it. Oddly, my MK3 didn't have one and the early versions of the MK4 RPS don't show them.

Before reassembling the master cylinder, wash all metal bits down with acetone or thinners. Get every bit of oil or grease off it.

Look at the exploded diagram above. Part number 13 is important and easy to forget. It is just a thin metal disk. There are a series of drain holes in the head of the piston and this disk blocks the holes as it compresses the fluid then lets the fluid back out as the piston retreats. If the one in yours is still nice and round, reuse it. Mine were really worn out of shape from rubbing against the walls, so I made new ones from thin brass shim.
The rest is easy. Drop the thick rubber washer in and press it right to the bottom. Clip the new drain-back valve to the large end of the spring. Drop it into the bore. (Make sure the metal cap is still on the small end). Dip the cup shaped seal in clean brake fluid and push it down the bore to sit on the spring, flat side facing up. The small end of the spring and the metal cap fit into the recess on the cup side. Drop the round metal disk down onto the flat side of the seal.
You should have removed the old seal from the hollow end of the piston when you cleaned it all. Fit the new one from the kit, dip it in clean brake fluid and slip it in as well. Push it down a bit and fit a new circlip. It's tempting to reuse the old one, but there's a good chance that at least one of the eyelets will snap off as you are trying to refit it.

Fit a new o'ring to the stroke indicator rod and fit it back into the air diaphragm housing. I put a bit of rubber grease in the hole to help it move and hopefully stop moisture getting in. Sit the air diaphragm housing down, with the big opening facing up. Put the spring in and try to get it as close to centred as you can. Put the piston in and press it down a few times to make sure it moves freely.
Here's a cheat. Flip it over and press it down until the housing is against the ground. Grip the piston shaft carefully with vice grips, making sure you don't scratch or gouge it. This lets you flip it over, pop the diaphragm in, put the end cap on and do up the retaining band. Work out which way the unit sits in the mounting bracket on the truck as the end cap has a drain bung in it that needs to point down. Also, make sure your retaining band bolts are located so you can get at them easily if you ever blow a diaphragm and need to get at it on the side of the road.
With the band tightened, release the vice grips. The piston rod will shoot back in. At this point, push the stroke indicator rod all the way in. If it won't go almost all the way in, the damn spring has moved and is blocking the head of the indicator rod. I had this happen. Only option is to remove the band and end cap and try to reposition the spring a bit.



With that done, refit the air actuator to the mounting bracket on the truck. Next, refit the brake master cylinder to the mounting bracket.
Refit the air and brake fluid pipes. Remove the filler bung and somehow fill it up with new fluid. I have it easy. The tray is off so I can get at the damn things. Try not to spill any or your new paint will all peel off.
Start the truck, build some air pressure and bleed the brakes, flushing the old stuff out. Don't forget to top up the master cylinder now and then. Maybe a mirror and a squeeze bottle with a curved pipe would be useful here.

On my F1, I fitted a Nitto air fitting to the inflation valve for the tires and diff, down by the driver's knee. This lets me connect my 240v compressor to the truck and pressurise the system. Handy when trying to track down leaks and will make it easier to bleed the system when I get to that stage. You could do this on a MK3 or MK4 as well, through the tyre inflation valve above the spare tyre on the passenger's side, but just remember that if you run the truck with this valve open, the governor won't unload the compressor when you hit it's normal limit. It will continue running and the over-pressure relief valve on the air reservoir will open, if its not seized up.

Greg.

Offline Chazza

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Re: MK3 Wheel Cylinder seal Kit's
« Reply #9 on: February 26, 2018, 09:49:08 AM »
Top post Greg still laughing!  :D

May I suggest methylated spirits, rather than acetone or thinners, for cleaning brake parts? A bit safer for the user's health and recommended by brake manufacturers.

I was wondering if a lever type press, made of something cheap such as timber, would be handy for holding the servo parts when assembling and disassembling. A weight could be hung on the end of the lever to overcome the force of the spring,

Cheers Charlie
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S2A 109" GS '63
S2A Fire Truck '64

Offline GGG

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Re: MK3 Wheel Cylinder seal Kit's
« Reply #10 on: February 26, 2018, 11:37:39 AM »
I think that we should have a special file for Greg's SOPs as he has some interesting ones. I note with interest his continued use of his boot as a receptacle. I think that it was coolant last time.  ::)
Geoff O.

Offline Ravvin

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Re: MK3 Wheel Cylinder seal Kit's
« Reply #11 on: February 26, 2018, 04:52:54 PM »
Yeah, metho would be safer.
The spring really isn't that strong. When I had to close one of the air actuators after moving the spring as it was obstructing the stroke indicator rod, I was able to stand the whole assembly on it's end on the carpet and press the end cap down against the spring pressure with one hand. Then I held it in place with my knee while I did the band up.
You aren't compressing the master cylinder as well, as when the air actuator chamber is closed, the end of the piston rod should just clear the end of the brake master piston. If it doesn't, you forgot to put the packers back in between the air actuator and the alloy mounting bracket.

Yeah, everything from coolant, brake fluid, smelly rainwater laying in tyres to bull-ants all seem to end up in my boots.
At work, I wear a pair of canvas gaiters to protect against blackberries and plantation harvest slash, but never think to put them on for working at home.

Greg.

Offline Andrew L

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Re: MK3 Wheel Cylinder seal Kit's
« Reply #12 on: February 26, 2018, 06:07:27 PM »
 Fantastic Post with great info:
 Im lucky enough that Both my Trucks had major break work in recent years but one Slave Cylinder weeped from that time.
 But I dont know how much was done and its one of those things that will need work again in years to come.

Offline Chazza

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Re: MK3 Wheel Cylinder seal Kit's
« Reply #13 on: February 27, 2018, 09:32:09 AM »
Probably a good time to remind everyone to check brake pipes for external rusting; it is often overlooked and with single-circuit brakes as on Land Rovers a rather scary thought if one leaks.

Have you changed your brake fluid this year? I haven't  :(

Cheers Charlie
S2 Command Recce '59
S2A 109" GS '63
S2A Fire Truck '64

Offline john.k

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Re: MK3 Wheel Cylinder seal Kit's
« Reply #14 on: March 05, 2018, 04:12:45 PM »
Hello,all,glad to see you re still hard at it....When you get brake cylinders stainless sleeved,its not impossible to have a leak between the sleeve and cylinder.,so its best to try them straight away,so you can take them back,if necessary.The other point is that sleeved master cylinders will have the bleed hole drilled too large,and with a razor sharp edge,and will cut a groove in the rubber cup quite quickly.Even orig cast iron cylinders develop this groove,because the cylinder is being used incorrectly.....too much force applied ....and IH should have used a proper booster cylinder....but they didnt.