Brake locking master cylinder issues

25th March 2012

I had been becoming more aware that it was not so much my engine carburetion problems that was preventing my buggy running correctly , but the brakes being applied whilst driving without the pedal being depressed. This was more noticeable whilst traveling up hills as the buggy would slowly come to rest with all four wheels locked. I could tell this was a hydraulic issue as If I bled the rear brakes. The brakes seemed to release and the buggy would roll again for a bout 5 miles before the problem repeated.

I decided that I would have to take the plunge and purchase a new master cylinder even though my previous master cylinder had seen little wear. GSF sell to different quality replacements and I went for the German. I decided to paint the Master Cylinder before fitting . I painted it with red oxide primer and Hammerite Hammered finish black paint. I left the bungs in place whilst I painted to ensure that the paint could not ingress into the internal parts.

The front wheel was removed to allow access to the M/C . The three brake lines was then undone with an 11mm spanner. Oddly no fluid came out of the MC before I put in the the bungs. I then undid the two 13mm bolts in the drivers side bulkhead and allowed the M/C to be removed. The general outside condition of the unit was fair. I drained off the brake fluid from the reservoir to a Jam Jar that could be taken and dispersed of properly. I removed the reservoir from the M/C as it is just a press fit and cleaned it thoroughly. The Brake fluid that came off the car seemed noticeably stiff. I took the rubber washers out of the old M/C and reassembled them into the new M/C. The Volvo reservoir was just pushed back into the grommets till it was seated.

The refitting process was pretty straight forward. I removed the M/C rubber hood and thoroughly greased the inside before replacing the cover. This whole unit was then passed through the bulkhead onto the activation shaft. Once in place it was propped in place and bolted through the bulkhead. The brake lines was then attached and the whole brake system was bled with a one man bleed kit.

MOT failures,brakes and a stiff test station

5th April 2009
Finally March has passed and the problems of the month seem to be disappointing. It has been a harrowing month of family problems some still not resolved hopefully favourably by the end of this week.

My buggy had also had an MOT failure. I had chosen the closest testing station Stiles Garage in Battle East Sussex which is a Ford dealer. It was also the Friday before Volksfest and I really wanted to have the buggy on the road.

The MOT test man pointed out 24 items that he felt in his opinion needed to be changed before he would pass an MOT on the car. To be honest some of these where very good finds the others seemed to be a little pedantic and ranged from bolts not protruding far enough from nyloc nuts to the wind screen wipers not laying flat on the body work, to the accelerator pedal being to close to the brake. I had a bigfoot accelerator pedal on the accelerator I think he didn't like it.

However the main failure was because of the rear disks. The rear disks did not seem to operate other than via the hand brake cable. Obviously this was very good to find and was worth the MOT test price alone.

He also did not like the noise that the exhaust was making stating it was obviously to loud lol. Funny I thought that was normal on a buggy. I had used a straight through exhaust on the temporary engine and realised I would have to create a baffle that would stop some of the noise escaping and offending people. A Friend suggested using a tail pipe from a beetle exhaust this was a pretty good idea as it had a baffle already built into it. The only problem was that the tail pipe and the exhaust where totally different sizes. Initially I tried securing the tail pipe into the exhaust with three opposing screws . This only slightly improved the noise level and it was obvious that the end around the baffle/tailpipe needed sealing. I thought I could wrap the tailpipe in exhaust wrap but unfortunately could not find enough material to wrap it up to the required size. Eventually a motor factor came up with a coupler that was a reduction pipe. Although this was not the correct size I worked out that it was the same size difference on both sides of the adapter. I sliced the adapter up its length and removed enough material to allow the pipe to fit. I remembered to use PI to work out the circumferences of the size i needed and the size of the existing pipe so that the difference between the two was what I removed. The adapter was then fastened on with exhaust clamps.

The end of March turned into a saga of fault finding on the buggy with the the hydraulic system being bleed and bleed and bleed with little success. I had read that the nipple should be facing up and not down so changed the callipers over from side to side. This also had the advantage of getting the handbrake cables further of the ground giving better road Clarence.

Unfortunately this did not resolve the problem I bought a Gunson pressure one man bleeding system that fitted onto the hydraulic reservoir. It pressurized the system 7up so that you could just bleed the fluid and the calliper nipple. This eventually gave some success however the rear brakes where now braking the pedal was traveling and hitting the bulk head which would be seen as another MOT failure.

I had spent the rest of March trying to think how to resolve this problem I placed threads on http://www.thesamba.com and on http://www.volkzone.co.uk . Eventually a member of the samba suggested that as my master cylinder was lower than my calipers I would need a residual pressure valve to keep the pressure within the caliper section up to 2lb. Now I was not aware by posting this onto volkzone that this would open a tin of worms. Several members of VZI said that this would not solve my problems other members suggested that my brake push rod length was the wrong length and might need adjusting. I ordered the residual 2lb wilwood valves and would have to try them when they turned up two days later. These promised to eliminate excessive pedal travel. I also managed to remember that these items needed a special adapter to connect them to the 10mm copper pipework as they where a Jic thread and ordered the adapters at the same time. I would also need to make up new hydraulic lines to connect to the valves. The lines would need to be 500mm long with two concave 10mm male connectors. In the middle 170mm from one end I would need to have convex female adapters. Bearing in mind the valve was 70mm long this would give me two lines one 170mm and one 260mm per side.

Later today i made another trip down to the garage and spent some time looking over the whole hydraulic system with a good friend and buggy enthusiast John. I had decided before coming that I wanted to check the brake pedal position something which was often overlooked when changing the master cylinder or removing and refitting the pedal set.The pedal was supposed to travel up to 3mm before hitting the piston in the master cylinder. Mine was over 15mm and once it was reset the pedal started to react better if not totally correct. A drip was noticed on one of the flexi-joints on the rear A-arm tightening this made the pedal movement a little better. I think the real change will be made only by the residual valves that i currently have on order and my hydraulic lines have been made up. My MOT retest was looming and I was not going to have time to fit the residual valves before the retest. The only question was would it pass or fail?

Preparing for the IRS/Gearbox conversion

6th March 2008
The garage was starting to fill up before I started on the stripping down of the back end. As the gearbox was coming out to be replaced by an IRS 1302s version, I stripped down the brakes to make this removal easier.

The removal of the wheels and drum brakes where fairly straight forward. The wheel bolts where loosened whilst the car was on the ground. As when the car was to be put on axle stands this would be easier to get the wheels off. Once the wheels where off, the drums where visible to be removed. These are secured with a cotter pin and large nut. The nut is torqued up to around 250ft/lbs so you will need a long bar with the handbrake latched on before it will budge. With this nut off it is best to back the pads off. These are retracted by rotating little star adjusters which re hidden in the back of the backing plate by two rubber bungs. You can rotate the star adjusters with the correct tool or a medium sized flat blade screw driver. Turn one at a time to ensure you are not winding them the wrong way and locking the brake up further. With the brake pads backed off the drums can be withdrawn from the shaft. Personally I use a long socket-set extensions held horizontally against the drum and between the backing plate. This can then be hit with a hammer to remove the drum. It is sometimes necessary to move the bar to the other side of the drum so that the drum comes off evenly. The backing plates must have the handbrake cable unhooked. This can be achieved by undoing the nut at the back of the plate that bolts the cable tort. Releasing this gives enough slack for it to be unhooked. The brake cylinder also needs to be disconnected and sealed up.The backing plates are held on by four 14mm bolts with these removed the drive shaft bearing cover plate can be removed and then the backing plate will come off. I placed the drive shaft bearing covers back on so that the bearings would be sealed.

Removing the the shock absorbers was just a case of undoing the respective bolts and removing the shock absorber. It is interesting that the only difference between the IRS and Swing Axle shock absorbers is the wider bush that sits at the bottom of the shock. The bottom bush can be removed by driving in a new one. I had removed the longer bushes from an old set of IRS shocks that I bought with the IRS parts.

You can clearly see in the picture right above that there would need to be some work with the fibre glass body sections to allow the IRS A-Frame arms to travel in their plane without hitting the body work.

I needed to get a friend to help me remove the gearbox as this was a heavy item that would need to be balanced on the jack whilst it was being undone. I would attempt this when a friend was available.