RUMCars Forum
General Category => Unusual Microcar Discussion => Topic started by: Bob Purton on June 29, 2014, 08:52:40 AM
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I thought it would be good to confess all the design faults we have discovered on our beloved microcars, not so much to mock but just out of interest and to give others the heads up. Lets face it, all microcars have them.
I will start.
The two Isetta's I have owned.
Leaky exhaust manifolds making the cab a little fumey at times.
play in the steering mainly due to worn bronze bushes on the link shaft. RHD cars don't seam to suffer so badly as the shaft is much longer. Hard to work on. Lots and lots of parts!
Point I like..... Sociable side by side driving, nice big sunshine roof, decent suspension, bullet proof gearbox. Excellent brakes.
My old KR200.
Terrible ride due
to tiny wheels and rock hard suspension.
Cant open the engine cover to tinker unless the whole canopy is open so if doing so in the rain the whole interior fills up with water and also soaks passenger.
Weak gearbox, prone to jumping out.
Hard to drive in a straight line.
Roasting under the plastic dome. Heat from sun in certain positions even melted the upholstery.
Brakes tend to fade.
Poor engine castings, clutch bearing breaks through casing.
Points I liked....
Fun to drive [until I started suffering with vertigo!] because quite nippy and agile.
Simple design, easy to work on.
Bond MKC.
Very poor brakes.
Points I liked.
Just about everything!
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In defence of the KR200
The suspension is hard, but without it you would not get the sporting handling. New rubber makes a huge difference. But it is hard compared to most.
Hard to drive in a straight line? - when not set up correctly, not rebuilt correctly or on cheap tyres. Just try a set up car and you will find it hardly deviates unless on a cambered road. It goes where you point it. I would suggest this one is an own goal. Its bad side is deviation from gusting wind. Stuart suffers from that too, after my curried Brussels sprout soup.
I would not call the engine casting poor. The issue is its a modified 150cc engine and has a poor clutch design in its entirety, really due to use of the same 150 gear cluster, which is also inadequate for 50 years service. However the car was made to last, possibly, 5 years. It performed excellently within its design perimeters, which now look very limited. The clear path forward is shown by John Bannell's Frankenschmitt which resolves most of the issues mentioned by use of better brakes, a bigger and stronger engine and a slight alteration in the suspension.
Other irritations of the Schmitt
Loose front seat, where the rivets get play in them.
Cracked steering bar. Not a safety issue as the steel inside must be whittled off a Tiger Tank. Its is some of the hardest steel I have come across! Its just an unsightly, but commonly seen, problem.
Lack of fuel pump. Even a low pressure pneumatic pump would improve the performance, with modern fuels particularly.
Brake cam design.
Some of the owners!
Isetta, additional
Wieght, they are heavy blighters.
Poor use of space
Poor layout of some components making for access issues or additional weight that could have been saved.
Poor front suspension geometry and execution. Over complicated, to many joints
Gearchange like stirring porridge on most. Over complicated, to many joints
Rear drive friction. Over complicated, to many joints
Yet made down to a cost so some materials used little better than case hardened cheese. What other car has cylinders that brake in half? Valves that fall appart unless replaced with properly manufactured ones.
Slow for its engine size.
Better competition? Could have been but for its own probs. Because BMW threatened to sue all potential competitors some did not invest in redesigning their faults out but moved production to beyond litigation. So many faults on some other cars are because of the Isetta!
Bond - additional
Tyre wear on front. The one wheel does most of the work.
Fixation on small doors. Not the only Brit firm to do this!
Barking whippets
Possible too eccentric to ever be the success it deserved to be in its time.
Reliant on Villiers to produce the good engines they eventually came up with, but by that time they had lost the best of the styling. The favourite, most wanted modern Bond was never made by the factory. A 250cc Mk C/D Tourer.
No slow running cooling/fan, no heating.
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I guessed that would trigger a mammoth response from Al!! ;D
All good stuff Al and I wouldn't dispute any of the Isetta knocking although I have never heard of cylinders breaking in half?? Exhaust valves on the Brighton ones, yes.
To qualify what I said about schmitts having poor engine castings, I didn't mean definition in execution, just the fact that the alloy that Sachs used was utter rubbish. If you don't believe me try welding a Sachs casting and then try the same on a British motorcycle casting of the same period. The Sachs one will spit something dreadful because of all the impurities in it whereas the British alloy will behave and weld admirably. Maybe this is why the clutch bearing flange gives way??
Funny you should mention a Bond MkC with 250cc engine, that's exactly what mine had fitted, went very well.
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but did it stop ! perhaps this is why you rated he brakes poorly ? :)
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Bond 875,how it was ever allowed on the road baffles me
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daniel , list the design faults to help us out
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Front end lifting over 50mph,no rollover strength whatsoever,minimal strength in the body and floor,a front end that pulls to one side when braking,and the other when accelerating,fuel tank located in a prime shunt location etc etc.
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Bond 875,how it was ever allowed on the road baffles me
You could say that about some of the drivers about nowadays.
Nobody want to rate the Peel P50? My old MHX 90C had the rear wheel chassis mountings 2" out of centre, that's why the lady owner fell over in it.
The other design fault I found in 1976, there was only one sliding window, absolutely useless when puffing away on my pipe and ciggies. I couldn't see out to the rear view mirror. ;D ;D
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but did it stop ! perhaps this is why you rated he brakes poorly ? :)
No Richard. I had a 197 powered MkD shortly after and the brakes were just as bad.
Now your turn to list the faults of the Gordon, I wonder if that pulled to one side under acceleration? I say acceleration in the loosest sense! ;D
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;D the car is in no fit state to tell but i will post some of the period reviews on that matter and it never appears to have caused a problem . see also NEXT RUM magazine - i am ahead of the game this time ;)
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To qualify what I said about schmitts having poor engine castings, I didn't mean definition in execution, just the fact that the alloy that Sachs used was utter rubbish. If you don't believe me try welding a Sachs casting and then try the same on a British motorcycle casting of the same period. The Sachs one will spit something dreadful because of all the impurities in it whereas the British alloy will behave and weld admirably. Maybe this is why the clutch bearing flange gives way??
The die casting does not break unless by outside cause or a crank failure. So there is no reason to weld it. The clutch bearing lip tends to fail as the engine is missassembled at some time and the lip stressed. There is a repair insert available that needs no welding. Strangely the case is stiff and accurate enough not to leak oil or air.
But the clutch is a poor unit and barely strong enough for the job.
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I have handled three of these engines so far with broken clutch bearing lips, I have no way of knowing if they had been "misassembled" in the past but if they had or if they had not it does highlight a design fault. The poor quality of the alloy cannot help surely? My impression was that it was the constant force of the clutch in operation that weakened and eventually fractured flange. The entire pressure of the clutch opening and closing is pressing against a flimsy alloy lip. Very poor design in my book.
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Moving on to Frisky's,
I'm not an expert but wasn't there some design fault in the front suspension? I think it required a modification.
awkward to get into due to the position of the doors in relation to the inner wheel arches as I remember.
Brakes are over sensitive.
I owned a Family three with a Villiers twin engine briefly and in general thought it was a great little car.
I liked the steering and the performance.
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I have handled three of these engines so far with broken clutch bearing lips, I have no way of knowing if they had been "misassembled" in the past but if they had or if they had not it does highlight a design fault. The poor quality of the alloy cannot help surely? My impression was that it was the constant force of the clutch in operation that weakened and eventually fractured flange. The entire pressure of the clutch opening and closing is pressing against a flimsy alloy lip. Very poor design in my book.
The bearing is fitted into the housing using heat. It is a friction fit. The lip is to locate the bearing in the correct place. In the same way that a woodruff key is there to guide and position a dynostart flywheel. The taper does the holding of it, not the woodruff key, which is in fact made to be sacrificial, unlike the clutch bearing lip.
Welcome Mr Hammer and Mr Whatsa - Shim. Either rebuilding a Sachs engine, its German remember, so you think engineering, is going to cock this up. Hammering in the bearing means it will damage its friction fit. It might fracture the lip too. Not shimming is to have a loose layshaft and a miniature slide hammer. To much shimming or a needle roller bearing fall over during assembly means the shaft is to long and will push the lip out. The engine is made to be built by people who understand it. Made well, it works well. Wynford, and others I do not doubt, have a selection of tools and a half crankcase to aid them shim up the engine. That is why Wyn, Nick, Pete etc get asked to do the engines.
This is not a design fault, but operator error. The alternative is to say its not idiot proof.
The design flaw is the clutch itself. The basket is to weak, I can bend it with finger and thumb. Even the later double drive plate noshs the edge of the basket up. The clutch bearing is an eccentric design and likewise weak. The central bush can get stuck and wear its end off. The 9 compression springs become weak, up the power and they begin to struggle to provide grip, to the extent plate kits exist to add 3 extra springs. (Not helped by the stronger springs being unobtanium for years and the Moped springs being substituted as it looks the same but has not the stiffer rating, so fails quicker under load. Not sure if this sourcing issue has been resolved).
There could have been a nice forged basket using standard bearings. Sadly you get a modified 150 system that does rather limit things. It is often the part that wears out first and a worn clutch can take out the gears, as they become loose, and also the casing lip. That is not the lips fault. Such a worn item should have spotted by a owner who is responsible and maintains his car as folk used to. You want to live in a service every 10,000 miles world, then do not buy a Messerschmitt or be prepared for a large bill for your ignorance.
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Frisky - Ooo eck. Get into trouble.
THe strut was original fixed to the GRP moulding and thus could not flex, other than by stressing the GRP moulding, as I recall. Later it was mounted in a better way so it could move. The rear mounts on top of the 'boot' still have great opportunity to stress crack.
Some doors were made so they went right into the wheel arch. This found water and crap geting in the door edge. So some cars have doors short of the front wheel arch.
Indeed much Frisky work seems to have been on the suck it and see basis. But at least they reacted to errors of judgment unlike some productions. I cannot comment on if this additional cost of continual improvement of design hastened the cars failure. The whole manufacture of the car seemed to be damned by internal politics and infighting. I think that was perhaps more of a failure than the car itself!
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Well explained Al. I will argue no further but only to ad the niggling fact that you can abuse an Isetta gearbox until the cows come home and it takes it like a man! ;D
Its amusing that we all know the design faults of our favourite cars but still go into denial! ;D
As the Apostle Paul once said "Love covers a multitude of design faults, sorry, sins" ;D
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Friskies... I can see how the suck it and see development method would be beneficial but also cause havoc for production. As you say, at least they responded to the faults.
A reworked Isetta using the same trial and error process over a few years would have produced a much much better car.
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I have always said that a fully developed concept would have seen the Trienkel outpace and outspace the opposition. Very efficient use of space, lightweight, engine had potential to be much more reliable and knocks out good power. Suspension rode well but was not adequate for road holding and needed more work. It was also a very simple car. Indeed think of a modified front axle and a modern twist and go engine in the back and you have a very usable car, perhaps only out of its depth on a motorway. Much as I like Messerschmitts it would not live with what the Trienkel could be for the most people. Its tandem seating would be to radical and unsociable and it does not offer the space inside that the similar sized Trienkel manages. The Isetta just does not figure I am afraid. But then Heinkel had the benefit of seeing the errors, did he not?
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The frisky door hinges were wood screwed into soft wood bonded in to the fibreglass. Thats why you see the doors dropping.
Why they could not use hardwood to solve the problem beats me as the cost was negligible in those days.
The front end lifts over 50mph and the steering goes very light. When i was 19 i kept half a slab in the front.
Solved both problems as it never went over 50 after that.
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Isetta fault
When I used to go round a large roundabout (at speed) the fuel would not reach the carb and about 3/4 round it would stall, just restarting in time as I ground to a halt (Right hand drive).
Also, hitting a particulate drain cover at 30mph on a left curve sent the steering into full tank slapper mode. Do you go faster or slower to stop it!!!!!! I used to take my foot off and let the steering wheel calm down by itself with just light assistance. Grabbing it hard just increased the effect.
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Yep I have had the fuel starvation thing. I cured it by shortening the fuel line. It also helps to keep the tank topped up. Funny enough I never had that in my RHD, only the LHD.
The shake of death as Jim calls it!
Usually caused by too much wear or free play in the steering. Cured by replacing all the bushes of by fitting a steering damper. I think the German made ones had one fitted. There is certainly a bracket welded to the chassis for it to bolt onto.
I have never experienced that, only read about it. Sign of poor maintenance.
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I will have you know that my Isetta cost nearly £100 at that time and as you can see from the picture was perfectly maintained (at some time in its past).
When someone bought my two Isettas (£150 the pair) but never picked them up. I left them in Westcliff railway station car park near his house and told him so. I assume they were both scrapped.....
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Heinkel gear change - pulling out in front of a juggernaut with plenty of room and then. 'What No Gears'
My Heinkel was a truly awful car to drive.
Compared to the Isetta it was horrid.
Bad brakes, gear change and having to rev the engine to get anywhere.
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Yep I have had the fuel starvation thing. I cured it by shortening the fuel line. It also helps to keep the tank topped up. Funny enough I never had that in my RHD, only the LHD.
The shake of death as Jim calls it!
Usually caused by too much wear or free play in the steering. Cured by replacing all the bushes of by fitting a steering damper. I think the German made ones had one fitted. There is certainly a bracket welded to the chassis for it to bolt onto.
I have never experienced that, only read about it. Sign of poor maintenance.
No tank baffling, then, unlike Trienkel and Schmitt. Good driving though, I approve. Good practice for turbo lag on a Saab!
No the steering geometry on the Isetta is bad. It should not be able to do its shake if the swivel and leverage points were in the right place. It would happily camber steer, which it does not. Would you let go of an Isetta steering wheel at 40 mph? Could go anywhere. The best I had was ex Phil Bowler white and blue 250 but even that was in a trance half the time.
Frisky had those BMC van door hinges with a brass ball with a hole in as the pivot. A bit overboard for a small bit of GRP but whatever. I did not remember the bit of soft wood till you said. I never got to understand the sometimes surface indicators, sometimes countersunk indicators.
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When someone bought my two Isettas (£150 the pair) but never picked them up. I left them in Westcliff railway station car park near his house and told him so. I assume they were both scrapped.....
Is Westcliffe along the Thames Estuary coast of Essex? I ask, as my good bud Martin collected several (thought it was three) Isetta from near some station and towed them home in one go behind his car like a row of ducks. We were young and indestructible in those flared days. Be funny if it were these cars.
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Heinkel gear change - pulling out in front of a juggernaut with plenty of room and then. 'What No Gears'
My Heinkel was a truly awful car to drive.
Compared to the Isetta it was horrid.
Bad brakes, gear change and having to rev the engine to get anywhere.
Oh dear. So many were like that. They do not need to be. Brakes bad? Better than most in class but given that this car was not working well elsewhere, it probably used to do the which side is going to stop first, trick, with accomponying run over Jack Russell sound effects.
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i found my Trojan brakes if anything a bit fierce but they certainly worked , noisy i would say but what the heck - better when lagged back seat a bit , awful fumes that i do remember - i always preferred when the roof or at least the windows were open . never any gear change problems really nicely set up probably by my old mate mike simmonds - he of 20 odd years experience with them .
the one design fault they all had was the service intervals , they have it right nowadays about 20,000 miles and even then not much to do .if they had been 20,000 i don't suppose many would have ever had a service yet !
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Heinkel gear change - pulling out in front of a juggernaut with plenty of room and then. 'What No Gears'
My Heinkel was a truly awful car to drive.
Compared to the Isetta it was horrid.
Bad brakes, gear change and having to rev the engine to get anywhere.
Well Barry, I have only had a brief drive of two Heinkels, one of which had a truly terrible engine that vibrated through the whole car and the other I couldn't find the gears and when I did find one I wasn't sure which one I was in. It put me off of those cars totally. Poor build quality as well. The front door always feels like it going to drop off when you open them. Isetta's are so so superior in every way!! ;D ;D ;D Are we getting tribal?
For Als benefit I WOULD let go of the steering wheel at 40mph on the motorway, I prefer to drive Thumper on the motorway to around town , the steering firms up nicely at that speed. Maybe its a toe in thing?
The rhd is a corruption of the original BMW version of the design and yes , the counter weight is a botch up but because of the aforementioned point doesn't count. ;) But strangely enough I believe the RHD set up actually improves the steering due to the extra long link shaft from worm to drop arm. Wear in the bushes of this longer shaft translates into less play.
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Is it true that some of the Isettas came with a lead silver painted brick offset under the seat, or was this someone's home brewed compensatory addition?
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Heinkel gear change - pulling out in front of a juggernaut with plenty of room and then. 'What No Gears'
My Heinkel was a truly awful car to drive.
Compared to the Isetta it was horrid.
Bad brakes, gear change and having to rev the engine to get anywhere.
Well Barry, I have only had a brief drive of two Heinkels, one of which had a truly terrible engine that vibrated through the whole car and the other I couldn't find the gears and when I did find one I wasn't sure which one I was in. It put me off of those cars totally. Poor build quality as well. The front door always feels like it going to drop off when you open them. Isetta's are so so superior in every way!! ;D ;D ;D Are we getting tribal?
For Als benefit I WOULD let go of the steering wheel at 40mph on the motorway, I prefer to drive Thumper on the motorway to around town , the steering firms up nicely at that speed. Maybe its a toe in thing?
The rhd is a corruption of the original BMW version of the design and yes , the counter weight is a botch up but because of the aforementioned point doesn't count. ;) But strangely enough I believe the RHD set up actually improves the steering due to the extra long link shaft from worm to drop arm. Wear in the bushes of this longer shaft translates into less play.
From my experience of both Heinkel and Isetta I do not see them both in the same league.
The Isetta has a chassis, brakes on all wheels, a 300cc BMW engine and build quality is superior. More torque, easier to get in and out, windows that slide back, better driving position, better gear change. etc.
Positives for Heinkel.......?
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Positives for Heinkel.......?
Isetta owners do not appreciate the finer points so despite its rarity there are still nearly enough to go round to those that do. :o
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WHAT????!!!!!! They don't have braking on the rear wheel?? Is that correct?
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Its a genuine microcar using minimalist design. Handbrake on the rear, hydraulic in the front. No need for a brake bias and the car is light enough that the surface area of the front brakes is more than adequate. The key thing is to not use the green coloured brake friction material. It is very hard and a more progressive pedal can be had with using a softer grade of friction lining.
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Like the Nobel then and by extension the Bobette! I actually quite liked using the handbrake with the foot brake when driving the Nobel as the hand book recommended. Felt more in control.
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Yep. Save the Heinkel has very good brakes. I have never had insufficient brakes to stop, I have had insufficient grip, which is entirely another matter. Cannot say that for my Nobs. But then you drive to cars performance and the Nobs I had were not that nimble either. The Heinkel is, done correctly, as it has a brilliantly simple steering rack and good steering (let down by the suspension/damping). So the speed is governed by the suspension, not brakes or power available, when its all working well. In addition the gearbox is good enough to use a downchange to aid braking/handling by shifting the centre of gravity back as you accelerate out of the corner earlier than not changing down. Here you will find many who disagree as they never had a gear change that was set up correctly nor were prepared to rev the engine as it is designed to be, prefering to plod. Get it wrong and you can easily tip over so its trusting your abbilities as mechanic and driver. Such a Heinkel would be nipping at the Messerschmitts heels and leaving the Isettas looking for another gear. I know, we proved it on several Story trips and runs through the Harz Mountains. This is not to say an Isetta cannot be driven with spirit but ultimately its great weight prevents it keeping up despite have 50% more volume in the engine. Cruelly shown on hills were the Heinkel is probably the best climber per cc out of the whole microcar group.
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Yes, Nobel is very underpowered in my view and I know Heinkel /Trojans can have spirited performance. I have driven behind some well sorted ones over the years and the same can be said for a few Isetta's. I remember one of the Stonham barns rallies a while back whilst out on the run in my Schmitt and having trouble keeping up with Barry Yellop in his RHD Isetta plus passenger! He used to drive/ride competitively in his younger years so I don't know if it was his driving skills or a breathed on engine that made it go like that. Another quite lively one was the one Phil Bowler murdered out to you. Generally as you said Isetta drivers plod , that's the style for me anyway, I would like to live longer! I wouldn't mind giving a Heinkel a serious go at some time but I have come to learn that one project at a time is the way to get em finished.
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Phils car had poor brakes, which were ATE of course. If not right the ali shoes expanded creating brake fad. I set the wheel alight driving it around Bath. Once I had sorted out the action and friction material it actually stopped! Despite being a 250cc its engine seemed better than the British 300cc. None the less, despite being the best driving Isetta it was not a car I would have zonked about winding miles in. An Isetta is very much a small car not an enclosed bike.
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Yes, I have also heard the old 250 motors were very good. The girling twin leading shoe system on the British cars is a better braking system though.
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Isetta Girling brakes are very good, especially the extra brake on the back wheel. Who thought of that idea? Clearly not Mr. Heinkel, who preferred hand brake turns to actually slowing down. ;)
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Heinkel aeroplanes mostly did not have rear brakes. He would not have noticed?
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I think Spitfires did have a back brake - who won the war? ;D
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Calm down boys! Remember, the idea of this thread was just to discuss design faults, not to get all tribal and take sides! ;D
Funny you should mention Spitfires, tomorrow I have to collect a dashboard from a Mk2 Spitfire aircraft, that's a model that saw action in WW2 and wait for it, turn it into a coffee table!!
I have agreed to do the job on the strict understanding that I will not drill any holes in it for fixings. I am prepared to use existing holes and also any bullet holes it may have! :D
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I have a Hurricane lamp!
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I have not just one, but two Wellington boots - a collector, no less.
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If you had three you would be Jake the Peg - and we know where this thread is going!