Researched by David Birchall
Ever felt that your Volkswagen 1200 wasn't the best-braked car around? Like to fit it with disc brakes? Well, you can! In 1966, for only $135 any Beetle owner could have them. A major Australian importer, LSD Trading Company, released the German-made Maico front wheel disc brake conversion kit for Peugeots, Porsches and VW 1200 and 1500. The Australian WHEELS magazine fitted the first set in the country to a staff VW 1200, and was delighted with the results, as the following report showed. The kits are still around today; I found a set for my '56, and if you keep looking you might find one as well.
The prospect of a VW with disc brakes encouraged them not only to test the car but also to write a stage-by-stage report of how they were fitted.
The Maico units are quite simple but incorporate many advanced design features. Both the calliper and combined hub-disc are cast from aluminium alloy, which gives a major weight saving. Because of the simplicity and lack of bulky parts, heat dissipation is extremely rapid compared with the drum brakes. The actual disc is a 24 mm wide hoop with an outside diameter of 280mm. This disc is bolted by five lugs on the perimeter to a five-spoke spider hub moulded with the minimum of metal to reduce weight but at the same time designed to be immensely strong. VWs have never suffered cracked hubs and they certainly will not with these alloy hubs. The bearings and oil seals are carried in the normal manner but the wheel studs are set in the hub, unlike the normal removable VW studs.
Because the large pads are actuated from only one side, the calliper is of the advanced swinging design. The pads are retained by a single cotter pin and are easily removable. The calliper is held in the mounting bracket by two rubber bushes that act as the pivoting points.
This could be a weak point of design as the rubber could be easily affected by oil. The calliper, which acts on the inside of the disc, is fitted with the hydraulic cylinder to the rear and set down about 15 degrees. The brake hoses are attached directly to the rear of the cylinder next to the bleeder nipple. The pads have been deeply grooved to prevent squealing - but more on that later.
Full instructions are supplied with the kit, and fitting would be well within the reach of most amateurs. However the local garage could easily fit them up and the bill should be no more than about $11 (in 1966!) For their project they had the co-operation of the then well-known Sydney VW and Porsche specialists Draper Motors, of Crows Nest.
The wheels, hubs, brake cylinders and backing plates were removed and the brake lines detached and wired back to prevent loss of fluid. The manufacturer stresses that the hoses must be in faultless condition, and you must replace the oil seals even if they are in good condition. Rebuilding now starts.
The disc is inserted in the calliper, which is held in place by the three bolts originally used for the backing plate. After cleaning and installing the bearings and new oil seals, the hub is grease packed and slipped onto the stub axle, taking care to line up the guide mark on the disc with the corresponding mark on the spider hub. Bolting the disc to the hub and setting the bearing tension completes the installation. Simple enough? Bleed the brakes, replace the road wheels, check pedal pressure and adjust rear brakes if necessary, buckle your seat belts and let's head for the Hardie Ferodo test track.
Before installing the discs, the drum brakes were tested for fade over 19 successive stops from 100 km/h. Stopping distance increased from 42 metres to 47 metres in the 10 stops, with noticeably primary fade in the last few metres. This represents a decrease in efficiency of 86 percent to 80 percent. Secondary fade built up over the 10 stops, and pedal pressures rose noticeably. Stopping distances from 50 km/h increased in 10 stops from 12 metres to 13.5 metres. This represents a decrease in efficiency from 79 percent to 68 percent. These increases are quite significant and would be multiplied by load and road conditions. The test car carried only driver and observer. Side effects were development of squeal, uneven braking and strong heat build-up on all wheel and hub surfaces.
The decade-old revolution of disc brakes was never more belated than it its application to the Volkswagen. With these huge 280 mm discs (1110 cm2 swept area), the Avon Turbospeed tyres tore at the bitumen to gain every erg of braking energy. The tyres smoked and the front end dug in as we recorded a very good distance of 10.6 metres from 50 km/h, which represents a deceleration of 8.53 m/sec/sec, or 83 percent braking efficiency. Our first stop from 100 km/h took 45 metres, which was disappointing, and most puzzling. Lockup in the last 3 metres could have partly accounted for this, and in subsequent stops we ‘backed off’ the pedal slightly to prevent this lockup, but this distance was still down on expectations. This final lockup indicated absolutely no primary fade - indeed, exactly the opposite.
Over the next five stops, using just enough pressure to avoid lockup, the distances grew progressively less: 44 m, 44 m, 40.5 m, 40 m (the fluctuation in the figures were caused by lockup on an indifferent patch of bitumen). A stopping distance of 40 metres represents a deceleration of 9.1 m/sec/sec and braking efficiency of 93 percent. Over the next stop the distance increased minimally to 41 metres. After all this punishing we immediately ran another ‘panic’ stop from 50 km/h in 10.6 metres, exactly the same as the figure recorded at the start.
The theory for the increase in performance was this. Over the first five stops the pad material would have been gaining its ‘working temperature’, where grab effect was greatest. The lowest distance of 40 metres was the result of the culmination of the most favourable conditions.
What does this mean to the average VW 1200 owner, who is content with his car so long as it goes where he points it and who probably considers expenditure of $135 (worth about $1,300 today) quite exorbitant? With the Maico disc brakes pedal pressures are noticeably lower for low speed work (65 km/h and below) but give increased stopping power. Now consider an accident situation with drum brakes.
There are these incidental points and features. The Maico unit had been available in Europe for many years now and at one time was offered as an option on the B series Porsches. Enough said as to quality? It had only been on the US market for two years at the time of the test, due to short supply, but they sold as many units as they could obtain. LWD Trading Company had only just gained importing rights after much negotiation and is the only Australian distributor, although we know that Maico was approached by many companies for these rights. Repco later sold them also.
Generally, on the road, the discs went unnoticed. They are not shrouded in any way except that the "deep" wheels of the VW help. After many miles on dirt roads, the dust did not have any affect on performance. It was not until later that the effects of travelling in dusty conditions were apparent. Hard braking and high speed braking would produce no squeal but after speed dropped to below 15 km/h a very penetrating squeal set in. Water did not affect the brakes in any way and it did not stop the squeal.
It would appear the old trick of cutting a carbon post to size and fitting it into the pads to act as a dry lubricant is needed here, or replacement with softer pads. They thought the squeal might go after the brakes had ‘bedded in’, but after 300 km they rejected this theory. As these conversion units were aimed at competition work, it is likely that these pads are of competition quality. This inherent squealing and high pedal pressures are the two main problems with most disc brakes.
In this unit pedal pressures were quite reasonable and do not have the same vague feeling as some. However, squeal has presented itself as a very real problem, but with experimentation it could be greatly reduced if not eliminated.
All in all, they felt these disc brakes were the greatest thing that happened to VW since Dr. Porsche. For the normal motorist the cost might have seemed high, but VW acknowledged the superiority of discs by fitting them to the Type 3 VW 1600 TL, which was not a high performance car. Fitting these brakes outside the factory meant a two-fold cost of the wasted drum brakes, on which very little could be raised to compensate, and the actual fitting charge, which would be far higher than the comparative cost in production line assembly. But for the ubiquitous VW 1200 it was of course unlikely that discs would be offered as factory options in the near future, and thus for the normal motorist the expenditure was worth every cent for the added safety margin. In the field of competition work and trialling this conversion unit was judged essential and without peer.
By Dave Long
Some time back, Andrew Dodd and I did a deal and I ended up with a set of well-used Maico front disc brakes. Now these little devils are intended mostly for Beetles, but they were also made for Type 3s, which are the ones I have (though they are to go onto a Type 1, if you get my drift). I follow the reasoning that if you are chasing something that is long since extinct, you have to grab it and make it fit somehow (for a moment there I started imagining 50% of a pterodactyl).
The ones for the Type 3 vary in the mounting of the carrier for the calliper to the back of each stub axle. The hole in the centre is an inch or so larger than for the Type 1 and the mounting holes are completely different, but there's enough meat in the casting to allow a bit of remedial machining. I have had a bush made up for the centre, and with that in place, correct holes can be drilled for high-tensile bolts with counter-sunk heads.
The above procedure enables you to attach them to the front end, but it doesn't stop there (pardon the almost pun). As I said before, with this kind of stuff you have to be happy with what you can get, and if you want to carry it through, being obsessive helps. On the set I got, the cast-iron discs were stuffed, having been rubbed hollow to half their original thickness. This left me with the next stage - to get replacement discs fabricated.
On examination, I could see that the pad lining material doesn't cover the whole area, no doubt for a reason, possibly that with a wider pad they are too efficient. But there sure is one way to find out - suck it and see. What I am getting at is that since new pads are unavailable (but you can get them bonded with new material), it is no more expensive to get them made any width you like, within reason.
"Ahah", you say, "but since the Maicos work back-to-front (naturally), that is, the calliper works on the inside of the disc, then the pad won't have anywhere to rub on.” Well, since I am up for new discs, I can make them with a greater area (that is, a smaller hole in the centre) to line up with the wider pads. I weighed up the options for making the discs and the learning experience brought me to the discovery that:
a) someone else's 343mm discs to cut them out of can't be found, and
b) welding cast iron is not a simple operation, nor practical in this case.
Some money was wasted experimenting with sone Citroen D Series brakes, then I was referred to an engineering company in Chatswood who have some quite sophisticated profile-cutting equipment, which proved to hold the answer.
Mild steel seemed like a crummy choice, then I was put on to a material called Bisalloy, which is expensive, but has other useful qualities, like good machine finishing and wear resistance. This resulted in discs that were cleanly cut out and finely finish-ground. However, holes to mount them to the hubs had to be lined up and drilled as a separate operation elsewhere. The Bisalloy, by the way, comes in about six grades, up to bulletproof. Mine was second from the bottom, so cost could have been worse.
Another necessity was to identify and obtain bearings of the correct size to fit the Maico hub and with the inside diameter to fit the Type 1 link-pin axle spindle.
So there you have it, almost. I’ll let you know how (and IF) they work.
Different people have told me different stories about how these brakes perform; Dave Birchall is the only one I know who has a set in regular use, and he reckons they are terrific. Apparently he had his own troubles getting them reconditioned and back into service. One of these was the hydraulic pistons, which were seized. He couldn't get seals readily and ended up machining out for a thinner seal (he has access to Qantas maintenance workshops, lucky bugger, but don't say I told you).
Others who had them further back said they were pretty ordinary, and I heard of several who had simply given up and thrown them away. I believe the early examples were pretty poor, and the Maico factory brought out an improved version. My knowledge of Maico is limited, though like a lot of European firms once great, they probably no longer exist. I do remember that they used to make motorbikes and 200cc scooters, amongst other things.
I like the brakes themselves, as they typically West German - well made.
By Dave Long
What about some bigger, better brakes for your VW?
How about Porsche brakes from a 356?
Early Porsche drum brakes are big, about 280mm in diameter, made of cast aluminium with a steel liner, and bristling with cooling fins. They are beautifully made, and if you are fortunate enough to have some 10-slot five-bolt wheels, they fit right on, since that’s where the 10-slots came from in the first place.
You can use both front and rear Porsche brakes on a VW if you want to, but so far I have considered only the rears, since I am so much into the idea of front discs.
It’s mostly a bolt-on operation. The Porsche backing plate bolts to the VW axle tube, while the splines on the drum slip straight onto the VW axle.
Where the fun comes in, and I haven’t done all my homework, is that the wheel cylinder, which I recall is 19mm, has to be enlarged. You have to increase the rear brake pressure, and you do this by increasing the size of the wheel cylinder. It took me a lot of contemplation to go firm on this. A lot of experienced people tried to tell me that a smaller rear slave cylinder was required! What is meant to happen is that the front brakes get about 60% of the pressure from the master cylinder. This works OK with the standard brakes.
For the Porsche rear brakes this may be a bit of a worry, because of the four mounting holes of the original wheel cylinder. This is the same as some very early Beetles (like 1953), including early Kombis, but there was no choice of sizes and anyway they are No Longer Available (what’s new?!) The only possible substitute I have come across so far is for a BMW 323, which I think has a 23mm rear wheel cylinder. It has two holes in the casting, which are of the same pitch as two on the Porsche 356 backing plate. This is all very much a matter of experimentation, so I don’t know if 23mm is big enough to make the difference.
It gets more complicated with front discs, because you can’t play around with wheel cylinder sizes, but then there’s the pressure-limiting valve that could offer a solution.
If you haven’t given up yet, you have to watch for a further complication – if the bigger slaves take more volume of fluid, the master cylinder (pedal) travel will increase, so you may have to also go to a bigger master cylinder, from a Kombi.
In case you didn’t already know, tinkering with this sort of thing involves stacks of compromise, and probably a lot of inconvenience before you reach your goal.
I haven’t mentioned that I realise a lot of this may seem a bit theoretical, since where are you going to get Porsche 356 brakes? This is fair enough. I realise that there were only so many of these cars made, and bits have to come from wrecks. Every car has only one set of brakes, and this assumes none are damaged at the time it was scrapped.
The same applies to wheels, though, if you like those slotted 5-stud rims, they came five to a car, and you are relying on dismantlers as your source.
The dismantler I refer to would be mostly enthusiasts rather than wrecking yards. One of my rear Porsche 356 brakes I got from Andrew a couple of years ago, and I matched that up with another from Nick Photios at Rose Bay. A couple of my wheels I scored from a former 356 owner who had sold his car, but had two rims hanging up in the garage – one was black, the other purple. I just got onto these by chance. You sometimes find stuff in the most unlikely places – you may find someone advertise a 356 door and bonnet. Try phoning him to ask if he has any wheels or brakes. The worst that can happen is that he says no (9 out of 10). It’s the tenth one that gets you what you are looking for.
On a Karmann Ghia, for instance, the rear cylinders are 19mm and the fronts are 23mm. If you tried an increase for the rear Porsche brakes from 19 up to 23mm, and with 23mm at the front, you still were not getting enough pressure at the back, maybe you could try reducing the size of the fronts in addition.
Another route is the use of Porsche 912 diagonal link arms and rear discs on a VW. A set of these would match with a 912 gearbox in a Beetle in place of the VW rear trailing arms on, say, a Superbug or a 1500 Semi-Automatic. These come up from time to time when 912 owners install 6-cylinder 911 engines to replace the 4-cylinder 912. They often replace the rear diagonal links at the same time, with a set from the longer-wheelbase 911. Likewise, bits like 912 4-cylinder tachometers, which have to make way for the 6-cylinder variety.
Another possibility for rear discs that I have half played around with, involves rear discs from an NSU Ro80. Interesting, but even harder to find than Porsche parts as they only sold a couple of hundred Ro80s in Australia. I saw some photos of the Opel Senator, on which the new Commodore is supposed to be based, and it had most of the Ro80 lines about it – 20 years on!
But back to the brakes. The NSU uses a rear disc, which has a small handbrake drum inside. The disc is meant to work like a normal front disc, with a bearing, so you will need to install the Type 3 spline attachment in its place, but it could be a big success. Also, the 5-stud bolt pattern is the same for the Porsche alloys, so if you want something a bit different, the NSU wheel is quite attractive. It is 14x5½”, and has a series of triangular openings punched around the centre.
By Dave Long
Have you had the unnerving experience of the brake pedal going limply to the floor of your Beetle? If so, I hope it happened at home in your driveway.
Once more, preferring not to be alarmist, but these things occur from time to time: someone will have to put it right. If you can handle it yourself, it can save you heaps, or get you out of a spot.
Fortunately, there are usually signs of impending brake failure; rarely do they just ‘pack up’.
If the brake pedal should go down quickly even a small amount, it may be a sign that hydraulic fluid is escaping, or bypassing one or more of the brake pistons.
To recap on the obvious, a simple hydraulic braking system consists of a master cylinder activated by a pedal, linked to a small expanding cylinder at each wheel.
Regular brake fluid is said to be hydroscopic; that is, it attracts water, which tends to corrode the cylinders, which are formed of cast iron. Problems like this are more likely to affect cars driven infrequently, because the moisture can then concentrate and attack one spot.
In my experience, this tends to claim the master cylinder in most cases, allowing fluid to slip past the cups. This is one cause of pressure loss.
The other is where a wheel cylinder loses fluid, sometimes due to wear of the rubber cups, also to pitting by corrosion.
In either case, the only solution is to replace the offending item. A damaged master cylinder must be removed. Reconditioned wheel, or slave cylinders as they are sometimes described, are available sleeved in brass and stainless steel. Shop around and compare with new prices to judge the savings, if any. Avoid brass, which is soft. Stainless steel doesn't corrode, and from that angle may be preferable to cast iron.
To remove a Beetle master cylinder, extract the two long 13-mm bolts, having first disconnected the three brake pipes, which have 10-mm or 11-mm unions. Do this carefully and avoid bending any of the pipes. They can be difficult to replace because of problems in lining up the thread. In any case, make sure the union moves freely on the pipe. And don’t forget to disconnect/replace the two wires to the brake light switch on the end of the master cylinder.
Most of this information concerns early models. The 1500 Beetle and Superbug have a split-circuit system with a tandem master cylinder and front discs, and calipers in lieu of drums/wheel cylinders. When it comes to leaks, the same general rules apply.
One aspect I have overlooked is the possibility of a broken pipe (steel) or burst brake hose. A closed hydraulic circuit which is disturbed by a fault resulting in loss of fluid will admit air, as will the step of detaching to replace a wheel cylinder or master cylinder.
Once either job is completed, you will need to remove air from the system.
Go behind each wheel in turn with a small glass container holding 20mm of brake fluid. Connect a 30cm length of small-diameter clear plastic hose to the bleed nipple, making sure the free end is within the fluid in the bottle.
Have someone climb inside and pump the pedal fairly vigorously. Them tell them to stop and hold the pedal steady. Only then do you open the bleed valve, allowing fluid to escape along with air bubbles, if everything is working as it should. When you have closed off the valve, and only then, you ask your assistant to do some more frantic pedal-pumping, then hold steady. Repeat the process until all traces of bubbles have disappeared.
Watch the reservoir constantly and top up with clean fluid. Never allow the level to fall below half. Important!
Repeat this operation at each wheel until all air has been purged from the lines, and the pedal is high and solid. A spongy pedal means air still in the system.
An outfit called Ezi-Bleed does this more simply, without the need for a helper. It consists of a plastic bottle and tube with cap to connect to the fluid reservoir, and a further hose and connector by which the bottle is pressurised from the spare tyre; all that needs to be done is to open the valve at each wheel and pump the pedal a few times. The rest is automatic.
The only hitch using this device on VWs is that you will have to adapt a cap to attach to the pressure bottle. This is tricky on early models, but makes it so simple. Sold by Mona Vale Brake and Clutch.
On the subject of brake failure, I will give you a short story. Twenty years back I was in the Army, based in Melbourne, and I had a succession of early VWs, including a standard, but loose and agile, '56 Oval.
One long weekend I drove up into the snow, roughly uphill from Albury, aiming for Mt. Buller where the Army had a ski lodge.
Most fun is to be had off the beaten track, so I motored the whole way up and down by some of the least likely forest trails, none of them on the map.
Most of the time was spent generally sideways along the edges of sheer drops off the mountainside. It was a quick and exciting drive both ways, and totally free of incident.
I had to be back on Monday at the barracks in St. Kilda Rd.
In the afternoon, returning home to Essendon, the brakes failed without warning in the traffic on the Swanston St. Bridge, and at 20 mph, lacking any way of slowing down, I stuffed it under the back of an EH Holden wagon.
I JUST FROZE UP. Since then I have tried to practice (or imagined) emergency stops with the handbrake. But when the emergency comes, you must concentrate hard to remember you still have a chance. There isn't much time.
By Rod Young
Are you like me in that you hate bleeding brakes? I don't mean "bleedin brakes" as in "bloody brakes", but changing the old, smelly, pernicious, water-laden brake fluid for the new stuff. Not only is it a two-person operation, it's a boring one.
This is the normal way of doing things:
Fill the fluid reservoir with nice, fresh fluid. Get your friend/enemy/wife to operate the brake pedal. Or anyone off the street will do. Prepare yourself with a length of clear plastic hose, a glass bottle half full of brake fluid and a 7-mm ring spanner. Crawl underneath the car, locate the left front wheel, then find the valve on the uppermost part of the backing plate. The little bleeder has a rubber cap on it. Pull it off, put your 7-mm spanner over the little bleeder and the tube over the top again and dangle the other end into some nice, fresh fluid.
Now give the orders to your helper. He/she/it has to do exactly as you say. Say "in!" Say it again, this time louder, in case your helper was daydreaming or playing with the stereo system while waiting for you to get ready. You know, the little buttons which lock the station into memory. But somebody is digressing; I hope it's not me. Your helper should by now have pressed the pedal in and there will be pressure in the system. Open the little bleeder and it will ejaculate into the glass jar. Your helper's foot will have sunk to the floor. Now close the valve and say "out!" and your helper should allow the pedal to rise. If you use other words like "down" and "up", or "actuate" and disengage", the process will still work, I can assure you. Continue your fun for as long as no discoloured fluid or bubbles come out of the tube. Top up the reservoir with more nice, fresh fluid, then move to the other front wheel and repeat the whole process, likewise the rear wheels.
This is a process that many of you would be familiar with; I could give you a long list of things I'd rather be doing.
Why is this lousy job necessary? Well, if you ever remove any major brake component, such as a master cylinder, calliper or wheel cylinder, the closed hydraulic circuit is opened to the atmosphere and when the parts are re-installed, you have to get those bits of atmosphere back out again. But even if you don't go changing components, it's a job that should be done every two years. This is a safety item of preventative maintenance that won't be carried out by your local garage when you take it in for a "service" unless you're in the know enough to specify it, but will be done if you have your vehicle serviced regularly at a VW dealer.
Safety is affected, because the brake fluid itself deteriorates with time. This is because it is hygroscopic, ie. it has an affinity for water. Any water that is attracted to the brake fluid, which it always will be, since the atmosphere is usually humid (it gets in the little hole on top of the brake fluid reservoir, but you mustn't block it) has two bad effects on your braking system.
Firstly, since water has a lower boiling point than the glycol-based fluids used in brakes, the overall boiling point of the fluid is reduced. This matters a lot if you're towing a caravan down the Bulli Pass, for example, because repeated applications of the brakes causes a great build-up of heat that soaks into the fluid, sometimes causing it to boil. When a liquid boils, bubbles of gas are formed, and the gasses are compressible, where liquids are not. This would be a case of the dreaded "brake fade" - panicky pedal to the floor type stuff.
The second deleterious effect of water in the brake fluid is rust. If water is allowed to collect in the master cylinder and wheel cylinders because the fluid hasn't been changed, it will attack their cast-iron surface and cause pitting. This phenomenon will eventually cause leaks. (Stainless steel liners are a good idea here).
The two-yearly brake fluid change should completely replace the old fluid. For this reason, it's important to get rid of all the fluid in the piston bores of the callipers. Some VW callipers are supplied with a second purge valve well below the little bleeder, which allows all the fluid inside to drain out.
Here's my method of bleeding brakes, which I think is an improvement over the textbook approach. You'll need a compressor, though.
Find an old cap from a fluid reservoir and drill say, a 4-mm hole in it - just large enough to get the tapered tip of a compressed air gun into it. Instead of laboriously pumping the brake pedal, your helper gets to pump compressed air into the fluid reservoir. Make sure he/she/it isn't heavy-handed, because if the trigger is pressed all the way, it would be enough to blow hoses off fittings or blow the reservoir up completely. If this happens, make your helper clean it up. Gently does it, just a little bit of pressure is all that is required. Next step - get a brick and chock it under the brake pedal. Then crawl under the car, open the little bleeders up once only, and all the nasty stuff will come out in one go. It's quicker and more fun than the textbook method.
The ultimate solution is one that appeals to me greatly. Replace all the brake fluid with silicone brake fluid. This has numerous advantages and at least two disadvantages.
The pros first:
- Silicone fluid isn't the least bit hygroscopic. You can work out the implications of that yourselves, I hope, from the details I've already mentioned, but for me the best thing is that you never have to replace the stuff.
- It doesn't attack paint. Paint being stripped by glycol-based fluid is a major cause of rust.
- It doesn't stink.
The cons second:
- Silicone fluid costs a lot to buy.
- It is harder to bleed tiny bubbles from. Therefore it's best to pour it very gently when filling up reservoirs.
To this person, who doesn't mind work if it's something new each time, but hates doing the same job again, even when it is interspersed by several years, the pros far outweigh the cons, and I'll be using silicone fluid from now on. If you have to open your brake system for whatever reason, you can re-use the old fluid, and even separate any water or glycol-based fluid that may be present.