MGB Register Forum

I am gradually rebuilding our 1972 GT but with a few modifications including fitting a dual or twin line braking system from a 1978 car which had been off the road for about twenty five years. I have searched the internet and have found that there doesn't appear to be any info on rebuilding them. My workshop manuals only cover the chrome bumper cars and was trying not to buy one for a later and not find any info in it.

I can't offer much useful advice, just a suggestion:

If it is Lockheed or Girling and you have a part number, try searching on the internet for anything relevant.
I bought a Lockheed rebuild kit many years ago, but it wasn't easy to fit.
I would recommend buying a new one for peace of mind.

Ian F

I rebuilt my in-line servo with out much difficulty. It was some years ago so I will have to look up records to remember how it went and what kit I used.

Have you tried to put the whole assembly in the car yet? On my 1969 GT I had to open up the aperture to get the pedals to go through the hole.

Like you I had to open up the hole for the pedals and added a couple of rivnuts where needed, other than that it was straightforward. I got some useful advice from the other MG Forum that we both visit regarding the dismantling of the servo. I was surprised to find the diaphragm to be soft and supple, really looking like new but it was covered with a gel of some description. The only part that definitely needs replacing is the seal around the pushrod from the pedal, but as yet I haven't succeeded in removing the valve on the pedal pushrod
However I still do need to know the gap for setting the master cylinder pushrod.

I Have opened the servo and it appears to be in good condition with the exception of the seal at the master cylinder end, the diaphragm looks like new. There is very little info out there even when searching with the aid of part numbers. Providing the parts fit correctly I will add a description of how it was done.

I've been diving through a mountain of old receipts from when I built my car from a wreck. The brake servo rebuild kit came from MGOC Spares with part number 18G9080 and cost £45 in 2008. I don't recall any special problem fitting the kit and it has worked ever since over 17 years and 39,000 miles.

Shout if you havent yet sorted out a set of brake pipes now you have a later braking system Philip.

I have a complete spare for a dual circuit late B in copper/ cunifer I bought a few years ago and didnt need to use.

Theres no point in me keeping them so yours for £ 5 plus postage if they are of use to you

Thank you for the kind offer Chris, I must remember to tick the box to be notified of replies in the future. I bought a rear line kit and will shortly fit it but with the RX7 front callipers I will have to accommodate metric fittings and also routing the pipes around the slightly modified engine bay so I will pass on your offer. You may be interested in watching these videos; https://www.youtube.com/watch?v=K1dBf2ftYR8&t=973s I don't mean to knock Henry's efforts but I do think that he is gradually moving into greater and greater problems, I hope that I am wrong. Hopefully my engine will come out for the last time before the bodywork gets prepped for painting, I think my mods are coming to an end at long last.
Going back to the servo, I bought the NOS servo repair kit and it arrived in perfect condition except for the master cylinder end seal which was as bad as my old one. The seller gave me a discount because that seal is no longer available in the UK. Moss USA sells them for about £2 though and someone from the MGEx is sending one over, he is also getting me a genuine master cylinder repair kit and the pressure differential switch, all of which are much cheaper over there. I discovered afterwards that Bastuck include the seal in their Master cylinder repair kit for about £14. Moss UK cannot supply the seal and Moss USA will not post it, a practice that doesn't help owners over here

The master cylinder rebuild kit arrived complete with the servo seal so all is well. After ordering the kit from Moss USA I found out that the seller that I bought the NOS servo kit from was actually selling the same repair kit but for LDV's 1975 to 1982 and then found out that numerous TR7 parts suppliers are selling both the seal and the master cylinder kit.

Get a new servo. I replaced mine as it was not working. After fitting new one I thought I would like to see what was wrong with the old. Nothing....
it just didn't work.....