RUMCars Forum
General Category => Unusual Microcar Discussion => Topic started by: Bob Purton on April 26, 2011, 02:53:22 PM
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My Isetta [Thumper] has developed a strange problem when in storage
over the winter. I went to get the car out last friday and the rear brake was
locked on, the hand brake had been left off so I knew it wasnt this that was
stuck but the linings had opened out by themselves and locked up the wheel. Out
of desperation I released the bleed nipple and some brake fluid under pressure
shot across the garage! This freed the rear brake but the pedal was still right
up tight. I started driving the car home but half way home the brakes started to
come on again by themselves, I released the bleed nipple once again with the
same effect and finally got it home. I did notice last year that the brake pedal
once depressed was taking its time returning to its rest position. I guess
something somewhere in the braking system is not allowing the fluid to return
and pressure is building up inside. I thought I would fit a new master
cylinder and work my way out from there replacing things untill I solve it. Has anyone got any
ideas or have experienced this before? One thought that crossed my mind was a collapsed brake hose?
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I vote collapsed brake hose as well. Otherwise the front brakes would be doing the same thing.
This seems isolated to the rear.
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It could well be Jim but I did fit a brand new hose on the rear last summer.[it could be a duff one] I have followed all the copper pipes through and none are crushed or damaged at all. I did have a simular problem once on a mini powered Berkeley and it turned out to be the master cylinder sticking. All suggestions welcome.
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Hi, from the depths of sunny Paignton (on hols with Lee T) combined guess is wheel cylinder
If brake hose collapse no fluid could get to wheel cylinder so brakes unlikely to work
Guess no2 adjuster rod from pedal to master cylinder has expanded so not allowing fuid to return to master cylinder
Guess 3 rear whel cylinder and handbrake lever arm have seized to back brake not allowing brake to self centre after application
Meanwhile still not done schmitt steering or points as Scenic threw up ECU faults and rev limit to 3K also locked its keys inside (not possible say Renault) so daughter has driven us south!
Let us know the actual solution========
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Hello Bob: I have a vehicle that I worked on yesterday and completed today. No, you may not ask what one, for you may stop reading this. During the year, the brakes work fine and stop on a dime, but when I park it for Winter, about November, and try to move it in March, the Rear Brakes are always seized. Not the single front one. (oops, cat's out of the bag). This has happened the past three Winters. I have to release the tightening adjusting screw which open/closes, the rigid end of the shoes. It always takes about three full turns. I never need to readjust. They are not self-adjusting. I just yesterday took all the parts apart, washed in cleaner, and reassembled, flushed out the lines, slaves and master, cleaned the reservoir, all with ethanol, blew it out with air and let dry overnight. and today replaced with Dot 5 fluid. I have no idea if this is going to fix it, I won't know until this time next year. Brakes work now as good as they ever did, but will they last next Winter? You can read all about this process in this coming up issue of Conveyancer. Later, Ian.
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Hi Ian. What a trooper! Still offering helpfull suggestions even whilst on your holidays! Sorry to hear about the trouble with the Renault.
I checked the rod and it had free play so cant be that, the rear cylinder was new last year and both this and handbrake lever are all greased and free moving. Will let you know if and when I find the fault. Cheers, Bob
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Hi Other Ian! Well well! It appears the three wheeler gremlin is creeping into our garages in the winter time and is tightening up our brake shoes! Isnt that weird! Its not the same issue as mine though as after adjusting the shoes I went on a run and the rear still just locked up again after a few miles. I will not be reading the story in Conveyencer though, the wife doesnt allow pervy mags in the house but will be treating myself to a copy of Stu-pots new book, there is Reliant history in the family and any book signed by Elvis has to be a good investment! Thanks . Bob
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Brake fluid is 'hydroscopic'!
It absorbs water, that's why they say never use brake fluid from a bottle that has been open for more than 3 months.
Could this be causing the 'nipple squirt?'. Damp garage over winter, poor seal on the master cylinder?
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so you don't get this excessive pressure buildup on the front brake cylinders?
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No Jim, Just the rear one. Even after releasing the pressure via the bleed nipple the brake pedal is really bolt upright with barely any travel.
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On rear hose failure. In winter it was very cold so the fluid will have reduced volume. If the pipe has failed, then on expanding, if relatively rapid temperature rise, it would pressurise. You freed it off. On driving it is exhibiting the normal failed pipe locking of brakes.
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Yep. I guess it has to be somewhere on the rear cylinder feed otherwise the fronts would be locking as well unless the pressure is going to the point of least resistance as there are two cyinders per wheel on the front. Thanks everyone for all the input. I will report back when the fault is found. At least this thread got us on a tech topic and away from ebay and the price of Peels! :D :D
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Right, problem solved but the jury is still out on what it was! The new master cylinder arrived this afternoon. I fitted it and decided to take Prof Ian Hellings advice and wind in the rear shoes by three turns. I have just returned from a half hour drive using plenty of braking and the locking up has vanished! Now was it the new master cylinder or the Hellings treatment?
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Dear Bob
My untechnical guess is that the sub zero winter temperatures are the cause of the problem as Ice can do a lot of damage externally and internally to components. and most metal components will contract. I have a rectangular box section on one of my cars that is almost round where being partially full of water, it froze and the expansion forced the RHS to balloon.
Now that the weather has improved the ice will have gone or returned to water, and the components will have expanded. Ian's suggestion of slackening off the adjuster may be just returning things to where they were last year. Why the rear wheel, that is a mystery, unless the slave cylinder, had some dirt in the bore, but you did clean it out and it made no difference.
Maybe you should consult one of the major brake compont manufacturers for their suggestions.
Chris Thomas
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Tense nervous braking? Then don't waste a second. Take Hellings!
Could be hydroscopic frozen water damage nurdlizing the master cylinder. Not a failed pipe.
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Still doesn't make sense to me, all cars suffered sub zero temperatures this winter but there brakes didn't lock up. It was new dot 4 fluid last Autumn so I am also dismissing the hydroscopic influence theory. I'm going with the faulty master cylinder idea. The previous owner told me he had just fitted a rebuild kit, this was last summer so there must have been a problem before to necessitate the rebuild and now knowing the inaptitude of the last owner I am putting it down to the master cylinder. If the problem comes back this winter I will have to eat a generous portion of humble pie which I'm developing a taste for! :D
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Yes, I agree it is a perplexing problem. ??? . I was thinking with my issue about the fluid being so old and with so much moisture in it, that it would freeze and somehow the extra pressure developed by the freezing caused the adjuster to operate. Just as if you rammed super hard on the brake pedal. I can see no connection between the adjuster and the slave. So how is it possible? And why not my front one? These "Winter Brake Gremlins" are tricky little urchins. I am now thinking that maybe with seasonal use, somehow grit or dirt is settling on the cams of the adjuster, and thus tightening it over use, and with the limited use I don't notice the progressive tightening. Then, over winter, the cams even expand more (30 below weather) and stick in a wide position tightening the brakes. When I did clean these out there was gritty dirt in there, but they did seem to operate. There is no protection for brake dust (or anything else) not to find it's way into this adjuster (open hole). Maybe I should find a plug to fit them? Anyway, after cleaning I did lubricate them well with dry graphite, so they should not stick, if that was the cause. I did estimate the gap between the cams to be about 25 thou when operating correctly, but alas there is no way to measure when stuck, for you have to release it to remove the drum, to measure. Catch 22. I don't think that your problem is the same Bob, but at face value initially did seem so. Let's see if this thread restarts this time next year. ;D
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time we put a stop to this one ! or should we just let it fade aw...............
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Yes Ian. We will confer next March!
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Still doesn't make sense to me, all cars suffered sub zero temperatures this winter but there brakes didn't lock up. It was new dot 4 fluid last Autumn so I am also dismissing the hydroscopic influence theory. I'm going with the faulty master cylinder idea. The previous owner told me he had just fitted a rebuild kit, this was last summer so there must have been a problem before to necessitate the rebuild and now knowing the inaptitude of the last owner I am putting it down to the master cylinder. If the problem comes back this winter I will have to eat a generous portion of humble pie which I'm developing a taste for! :D
Ah ineptitude. Very often the basis of a problem and sold to me as I spent much the last 25 years sorting that out on cars bought in. Funny how things work when assembled correctly 'innit?
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Can I just extend the discussion to Messerschmitt brakes. I have an unusual situation with mine. They work!
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Can I just extend the discussion to Messerschmitt brakes. I have an unusual situation with mine. They work!
No they don't Al, it's just you pushing your clod-hoppers through the rust holes in the floor and pressing them down hard onto the road Fred Flintstone-style.
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Dear Al
Congratulations
It appears to me that the brakes on Bob's Isetta also work well, infact the rear brake works too well.
As I see it, brakes are there to slow down and stop a car (under the control of the driver). I would be more disappointed if they did not stop a car from moving. The issue appears to be that Bob wanted his brakes to release under the control of the driver, which is the opposite of them working. Not unreasonable when you think of it; especially as the front ones are releasing.
I am sure that with the engineering knowledge and skills Bob has all will be revealed in the fulness of time (next March)
Chris Thomas
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Ho Ho Marcus! I think Al is having at pop at me for deserting the world of Messerschmitts for a brand of car he doesnt like. I think though now I have rebuilt just about everything on the car it will be a good un. I do admit that during the ten years I owned the schmitt it was very very low maintenance, all I ever had to do was adjust the brakes[frequently], change the oil and set the points but then again the car was restored properly in the first place! I miss the schmitt but not the vertigo attacks it gave me whilst driving it!
Thanks for the vote of confidence Chris but my "engineering knowledge and skills" dont extend to girling braking systems, mercury barometers yes! Theres a thought, fill the hydraulics with quick silver, now that WOULD respond to temperature change!!
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Hi, still Paignton location, keen to know what actually failed! rubbers? bore scored? big lump of rust dropped in and circulated? is it still there? acting as a valve in the three way connector?
Forensic mechanics is of great interest to me. Easy to break stuff or inherit previous dubious quick fixes but real credible (safe) solutions of more interest
(recent broken schmitt track rod end springs to mind) nearly resolved with thick track rods and real schmitt rubbers both ends and middle, just need to learn how to fit and time up new points
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I'm not really sure Ian. I dismantled the old cylinder and found nothing obviously wrong inside other than the fact that the spring was much weaker than the one in the replacement. It could be that the piston was not returning fully after being pressed in. Today I partially solved the steering wander, It turned out to be something that you mention earlier. The big center nut that holds the rear wheel hub on the splinted drive shaft had become loose, I have already nipped it up a couple of times but even though there is a split pin holding it , it kept coming loose. This time I thought I would really get it on tight with the use of a tube over the end of my socket wrench, I got it pretty tight but then suddenly I was able to give it about three more complete revolutions and could feel that the shaft was being drawn through the bearings inside the chain case until it came to a positive stop, it appears that the guy who rebuilt the chaincase had not drawn the shaft through the bearings fully, he must have stopped tightening the nut when it offered resistance, hence with use it kept moving. I immediately noticed an improvement with the steering, less wander. There is still some more improvement to make I think with a better worm and nut but all in all a good mornings work!.
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Might be pertinent to Isetta. Trienkels suffer from play on the rear axle. You would think that tightening it up, with the drum washer the correct way round, would solve this. It does not as the distance tube fitted over the axle to keep the two rear axle bearings in place either end of the casing but in tension is of poor quality steel. It therefore shears within itself allowing more play. Tighten it and a few months later it is loose again. Both Trienkel and Isetta rely on the splines of the hub to be a good tight fit to avoid rear steer. Clearly a sloppy rear bearing allows play and the spline is the weak bit. Once worn it is not easy to repair. So if you have a Treinkel sling the old tube and get one made out of proper steel to replace it. The club should sell these but historically refused to do so. Isetta owners take advice from someone who knows as they might have the same problem.
I like the mercury auto weather brake system. Fair weather, brakes work, can go out and play. Wet and windy, brakes seized, cannot go out and get the car wet.
Messerschmitts are renowned for the invention of the perfectly free functioning frictionless brake system possibly backed with ali brake shoes which only touch at either end of the friction surface when hot. Any Schmitter worth his salt has had to find himself parked on the pavement next to a line of traffic at a red light calmly looking over at them and going 'hi, guys. It's only me'. Further fun is peeing on the front wheels half way down a steep hill to get them working again, like going into Koblenz from the Autobahn Koln - Karlsruhr. So good are Schmitt brakes that they are at their most exciting when the car runs at its best, just after a rainstorm on a hot day. That bit of water vapour cools the charge and magnifies the power. Sadly the tyres do not grip well, or at all if cheapo boys, and the brakes rather crude on/off, well having thought about, off actually, nature can make for some very interesting experiences. Otherwise you drive slowly and the brakes are about adequate but that is really rather boring and you will be left behind by the pack on a run. Perhaps why Schmitts are not everyone's idea of transport as they do tend to suit the nutter element who have little time for dawdling.
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Dear Bob
What would be the effect of using mercury in place of break fluid be?
Does Mercury boil at a lower temperature than brake fluid?
Would there be an electrolitic action between the Mecury and the Copper brake pipes, or the Aluminium Master cylinder components?
Would you ever need to change the Mercury?
Apart from weight, why have the Formula 1 racing boys never thought of using Mercury (apart from the health hazard)?
Chris Thomas
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Chris I was only joking! But as you ask, Mercury 674 F and Dot4 dry 446 F but lower if moisture present. One advantage of using hg would be that it doesnt hold water. Disadvantages would be it would eat through copper pipe and eat the Cylinders out even quicker and then amalgamate. This could be solved by using stainless steel tubes and cast iron cylinders which I believe old ones were made from anyway. Would most likely last a long time too. Other disadvantages, its very expensive to buy triple distiled and heavy as you say. There is one other draw back that I can see and that is it has no lubricating qualities unlike brake fluid so it wouldnt work with piston rubbers. Dangerous? This is scare mongering clap trap from our EEC friends, ok its dangerous if you drink it or boil it and breath in its steam! Then again so is brake fluid and a whole host of other liquids that that you can buy down the shops! The EEC have banned production of new mercury barometers other than for the MOD which fortunately has not effected the three surviving manufactures who will now make you a nice reproduction Daniel Quare and supply it empty. The customer can then hand it straight back to them and request that they quite legally service and refill with this dangerous stuff there used/second hand barometer. What a load of nanny state clap trap! Someone at Brussels had to sit down and think about how to stop these three people from churning out all of half a dozen barometers a year that would be so dangerous. Meanwhile all our low energy light bulbs containing mercury get chucked into landfill by the millions every day! It makes my mercury, sorry blood boil!
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the plot sickens!¬ I was always told that the rear nut you mention should be F T (second T=tight!!!!!!) any less and the splines will wear.
I use a long britool bar 1/2 drive and a length of tube also never loosen to get pin through castelated nut keep going on tightness. No doubt plenty of other advice will follow.
is there any rear wheel movement vertically or horizontally? maybe splines or bearing! there is a newer bearing that has a groove and a grease nipple can be added to the casting to enable extra lube as the oil swishing around in the chaincase may struggle to get to the bearing ? comments welcome
pleased to hear from no one regarding my glass excess as it means no one else has smashed bits! Attic is calling.
Back soon first show Abingdon week tomorrow
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Dear Bob
So apart from the lubrication of the rubber seals, your suggestion was not so stupid.
It sounds like Mercury is quite agressive.
What could you use in place of a rubber seal?
Perhaps you should patent the idea before somebody else does.
Chris Thomas
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Chris, from what I hear if you start off with clean pipe work and new cyclinder rubbers silicone is a better option.
Ian, I did still feel some wheel movement after tighening the axle nut but it turned out to be a knackered wheel! The countersunk holes showed excessive wear and enlargement and as a result were just not biting down fully, it looks like someone had been driving the car with the wheel nots loose. I swaped it over with the spare and it tightened down fully, no free play at all now thank goodness! The car is now feeling pretty nice to drive and I'm warming to it.
Anyone got a good spare Isetta wheel? The one piece tubeless type?
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Apologies if following is obvious but I have seen rears set up with bits missing/modified poorly etc
I think that there should be (starting from brake drum ) a conical threadless spacer the wheel right (wrong!) way round
a large washer then the actual threaded shouldered nut-the big meaty washer goes against the wheel and up the shoulder so takes up about 3 or 4 mm
Do you have these? the stud ends up about 5 or 6 mm from nut top --Maybe this makes sense!
Still Paignton
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is there any rear wheel movement vertically or horizontally? maybe splines or bearing! there is a newer bearing that has a groove and a grease nipple can be added to the casting to enable extra lube as the oil swishing around in the chaincase may struggle to get to the bearing ? comments welcome
Should be no play. There is no great prob with lub on these bearings to my knowledge. The oil from the chain gets around enough to do the job on open bearings but you could use sealed bearings OK I guess.
Slight change in plan. NAF is not going on the road but Sarge is. Tatty red Schmitt. Should be starting it today with a good clean up and looking at the front suspension and steering. So hopefully be on the road in a couple of weeks depending on the Van (needs MOT and has tasks doing for contrat at Sandown Book Fair and moving a 22 ton Cotswold stone roof from Hay to home a pallet at a time amongst other things. If the Goggo is sorted we can heckle Nick with his Nobel and see if we can get some unified visits going, not least a workshop day to sort out issues. Roger is now working on his Schmitt. Graham's car is already going. Might finally get a cell together. That might kick several others round the county into action as well.
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OOPS forgot the big 4 hole thick steel ring! this goes against the wheel Then the meaty individual washers (4) then the shouldered wheel nuts
must remember not to post when 200 miles away from car also not after going to see Stan Web and band Chicken Shack live!! last saw him in 1967 at Torquay Town Hall
Double Diamond, Wrexham Lager, Starlight bitter and just passed driving test No2 (for car) test no1 for bubble car passed a year earlier age 16 Those were the days
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Yep, did my driving tests in the same order. About the rear wheel set up, yes you are stating the obvious but much appreciated all the same! Hope the sun is still shining in Paignton. I was down in Looe last september, love the place!
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I love the West Country! Looe is nice, but just a bit further along is Polpero. I have played at the festival there a few times and had a fantastic time. Loads of shops selling Cornish pasties, Cornish ice cream, fish and chips and great beers, like Sharp's Doombar and St Austel ales. Once past Solstice Park everything is better!
My Trojan used to wander a bit, so Goggo asked what rear tyre pressure I had and I told him that it was set as in the handbook. He told me to put it higher and it work wonders.
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1967 at Torquay Town Hall
Double Diamond, Wrexham Lager, Starlight bitter
Starlight Bitter, good grief, 18 pints of that and you got a bit merry! What happened to Double Diamond. I believe it was one of the first beers brewed specifically for canning/keg along with Newcastle Brown Ale (Dog) which is still very much with us.
Cannot say I have had Wrexham Lager and I think I am probably rather pleased. Most British lager is crap and I feel that Welsh heavy industry would produce beer drinkers traditionally.
Newquay Steam Lager, mmm! Doom Bar, even better and available at my local hostelry as the option to the session beer if your just popping in.
Sorry, its RUM car not BEERcar. The two things used to go together like Campervan and trailer though. Ho hum.
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Well I drink very little these days, but when I do I always go for quality rather than quantity. Cheap beer, cheap coffee and cheap bread are a waste of money. There's a pub quite near the Tatty Sark in greenwich which sells Doombar, and catering largely to younger and trendier people than I led me to believe that it would be badly kept and poured. I was amazed to find it was absolutely perfect, and even two of my nieces liked it.