RUMCars Forum
General Category => Unusual Microcar Discussion => Topic started by: steven mandell on August 03, 2014, 02:20:36 AM
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Historical review;
I first saw this Minicomtesse in the Sales and Auctions section approx. one and a half years ago. Remember the silly picture of one doing a wheelie while supposedly towing a big car- yeah that was the one on EBay UK.
6 months later got it to L.A. to discover engine not working, and clutch exploded internally partially stripping crankshaft splines.
Now, approx. one year later I hope to have finally conquered clutch issues with parts rounded up from US sources, and much detective work re orientation and shimming of parts. This was needed because I was not able to find enough good reference material, and both the parts that were shipped, and the clutch as it came were apparently assembled improperly.
My first attempted test ride brought heavy balking and stuttering and no forward propulsion. The engine idled well, but I was hoping that perhaps the extra loading of engaging the wheels and attempting to propel the car and myself was showing a lack of engine tune rather than a still bad clutch, and that that was what was causing the commotion without motion.
After another day struggling to get at the points (engine cover held on by slot head screws recessed into tunnels too narrow for impact hammer, and likely tightened by a Gorilla 20 years ago), I got the ignition spot on.
The points were in good shape, but gapped 9 thousandths too large and opening 2 m.m. too soon.
This time I cleared out a path through the microcar patch all the way to the road. It took off surprisingly well, but upon the dreaded shift into second gear a resonance started that if allowed to continue, felt like it would rip the front wheel and engine right out of the car! The equivalent phenomenal on 2 wheels is called a "tank slapper". But why only upon the up shift to second gear?
I know that some sort of destructive, amplitude summating resonance must be getting initiated here, but I don't know exactly why these apparently unrelated parts are conspiring to self destruct. Therefore, other than immediately backing off the accelerator pedal, which stops it immediately, I also do not know what to do about it to stop it from becoming activated in the first place. Sure I could and likely will put a steering damper on it to quell the chicanery, but why is it necessary for me to be dealing with this?
Anyone heard of this happening in other Comtesses or other single front wheel cars.
The steering seems to have very little play- only about 1/4 inch either side of center at the steering wheel.
I have seen a diagram with French titling previously that appears to be showing how to set the chain tension on the steering gear that has the engine sitting atop it. But with a total steering wheel play of at most 1/2 inch, could this really be what is at cause here? :-\
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Mate it sounds like it's behaving like a shopping trolley , if a bike had completely upright front forks it would tank slap , it needs to have abit of an angle to it like / , Maybe some shims are missing to make that angle
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Need it in front of me. The others I got going never did that. However any loose element or wonky drive could promote instability. I am slightly concerned when you state that the new clutch was assembled incorrectly.... And it happens when that is asked to operate, but is otherwise OK. What happened about the worn spline? Are we visiting the original problem that broke the car, that was never fixed? More sleepless nights I fear.
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I understand that increasing the rake of the forks would diminish this tendency.
However this is a non adjustable aspect of the car's design, so it couldn't be the deciding factor unless it was built wrong and did this from new.
Given the gravity of the shaking, that seems very unlikely.
So, assuming that I could redesign the front end fork angle, this could be a potential means of compensating for the thing that is wrong with mine that isn't wrong with the others. But it would not be fixing the thing that is no longer doing its job the way it used to, as we still don't know what went wrong.
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Al,
I was only able to get a lightly used almost complete clutch.
The condition that I received it in turned out to be assembled incorrectly. But that was probably because who ever took it out couldn't remember how to put it back together.
In consideration of the fact that my original clutch was severely damaged, it seemed more wise to trust the undamaged lightly used clutch's assembly pattern.
It wasn't until I took the clutch off for the second time, and just struggled through trying to figure out what its parts were trying to tell me about how it should be shimmed and assembled that I realized that neither clutch probably was likely to have been assembled correctly in the condition that I had received them.
I carefully, and lightly filed crank splines. Only the last quarter inch or so that only engages the manual over ride to up shift into second gear is seriously compromised. I used a metal filled epoxy on that last quarter inch to partially compensate for the loss, but do not plan on taxing the connection by pulling the rubber handled, dash mounted cable control that would cause manually instigated 2nd gear engagement. That is usually reserved for jump starts.
So I'll just make sure my battery is fully charged, or that someone has jumpers nearby.
That leaves me looking for something loose whilst the steering feels quite tight.
How would one check for vertical play in the steering head, and what amount of play would be considered to be normal?
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Other things that might cause tank slapping would be something running out of true or out of balance which increases in rotational speed when you shift to second or something that is flexing under load. Could something have been bent or forced out of alignment when the clutch was wrongly assembled by some ape trying to make it fit?
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It seems to be triggerred by the transition into second gear, rather than the absolute speed of the rotating masses, as if I back off slightly during the upshift, the whole cascading calamity stops/ is avoided, and both engine and vehicle speed continue to rise smoothly.
The crankshaft does extend about 3 inches beyond bearing support to connect with the inner splined elements of the dual centrifical clutch mechanisms. Wonder if that part could be bent, and how to check it without removing the 2 speed tranny/ clutch?
What could flex under load?
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What could flex under load?
A hairline crack or broken weld in the right place.
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I like your reasoning, but we all seem to be missing the mark so far.
Schedule permitting, I will do a brief inspection and attempt to post a picture or two of the fork/ engine mounting next morn.
On a car as lightweight as the Minicomtesse this structure is shockingly overbuilt on a massive scale- so doesn't seem likely to have failed.
But something obviously has, and there aren't very many parts that could be involved with a car this simple.
So it makes sense to go over the few there are with a fine tooth comb.
I hope it gets tangled up in something that's easy to fix.
Any suggestions as to how to check out the single front wheel front end?
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As the pics show, this is the only part of the vehicle that appears unlikely to fail.
My biggest open end wrench wasn't quite big enough to wrap around the big nut atop the steering axis.
But pushing the car in line with the front wheel axis demonstrated no percievable play between the side of the wheel rim, and the heavy bent plate that mounts the engine and front wheel spindle, and there is no shock or spring to complicate matters.
It is very simple, but I have no idea what it is.
Well at least it didn't disqualify it from entering the Concours de Lemons in Monterey in a couple of weeks. As a matter of fact it just now earned the dubious distinction of being officially accepted into the program. ;D
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Take the chain off and tow it , see what happens
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No idea whether it would make the slightest difference to the handling or not, but one thing that looks a bit different on your car compared to some other pictures on the net is the diameter and positioning of the plastic chain tensioner. Some appear about twice the diameter of yours and most have the tension point a lot closer to the outer edge of the front tyre than on your car.
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Good observation.
That would put the other cars chain tensioner closer to mid span, which I would think should be more ideal.
Perhaps incorrect drive chain tension could be a factor in creating this resonance.
Anyone know exactly where to measure, and how much forced slack I should have?
I would like to be clear on if the amount of slack is measured by pushing just one direction against The chain length, or if it is a total measure of the amount of slack created by pushing in opposite 90 degree tangents to the chain length, or about twice this amount.
That is something that I have been unclear about several times before.
This just in, I bought another Minicomtesse today. However it is unlikely that I will see it for another few months.
So immediate utility for comparison purposes will not become available before I would like to have this one handled.
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Still would like to know how to establish correct drive train tension.
But that didn't stop me from taking my own advice to Bob re how to establish correct toe in with radials. That is, I measured my current , as it came to me drive chain slack of 1/4" each side of rest / total of 1/2", and then loosened it up a bit to produce 3/8" each side of center for a total of 3/4". It is just possibly starting to shudder at a slightly slower rate of oscillation. I'll have to figure out some way of measuring the speed of shuddering before I can know if that statement is true.
But the magnitude of the "tank slapping" overall did not seem to be diminished. I made an observation seemingly consistent with my prior observation that lifting off the go pedal momentarily during the transition to second gear engagement by its centrifical clutch, stops the whole cascade of horrors, and allows the car to continue to accelerate unimpeded. The consistent observation is that, the shaking is worse when proceeding up a slight incline, and not as bad when on a slight decline. So apparently the amount of load that the drive train is under affects the degree of shaking.
I no longer think that the chain tension is likely to be the primary at cause culprit here. What a shame, as I had visions of an overly tight chain oscillating like a stretched, then twanged rubber band. Although it still seems likely to be exerting some secondary effect- especially if chain tension does affect the rate of oscillation.
a possibly more fruitful image that has occurred to me via thought experiment, is that an oscillating drive train speed as the immediate inductor of steering shudder seems quite likely, as the drive sprocket for the single front wheel falls necessarily displaced from the wheel's centerline. The chain would have to run through the mid tread of the tire for this not to be the case. So an oscillating speed of the chain should produce oscillating torque steer. I now think that this is what is happening here.
It also occurred to me that my use of the correct amount of automatic transmission fluid in the clutch bath could be a factor.
I went with info I saw on the Fox Sundowner minibike forum on these shores for this recommendation. I think that if it were the wrong fluid, and that was prime cause here, that some irregularity of first gear engagement would be noticed also- and it isn't.
But why just when second gear is engaging? Bent outer bell of clutch causing intermittent contact during transitional engagement?
Irregularity of anti centrifical force spring that resists expansion of the second gear clutch?- less likely, as it looked OK.
Feel free to chime in with your theory, or better yet an easy to do test that would generate inescapably significant results that point to the true cause of origin of symptom.
Best case being someone with a 2 speed centrifical clutch car having had and conquered this problem before.
Jean Do? French Minicomtesse club- are you out there? :-\
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i can't say I ever noticed any sign of tank-slapping with mine. I always found my steering was totally and utterly neutral; it went where you pointed it and you pointed it where it goes. I can't remember if mine self-centered or not under drive but I know I had to shim out one of the small steering chain sprockets and also to tighten up the steering chain DEAD tight to stop the steering chain pulling off on full lock. The slightest precieveable slack in the steering chain and off it would fall at full lock.
As regards shuddering when changing up into second, I never noticed mine doing such, but then mine would never change up automatically, only manually, so I was probably too busy holding steering wheel in one hand, pulling gear-change lever with other hand and blipping throttle with foot for just the right rev range for the gear to take in, to notice any peculiarities as the gear fed itself in, as all the above often had to be done three or four times in quick succession before it felt like taking second gear.
I can't recall ever having to touch the main drive chain for any reason.
Edit; try changing up manually a few times & see if it still shakes that way?
Of the battry/cubby boxes over the rear wheel arches, these were just simple open-topped fibreglass boxes sat on top of the arche & bonded to the inside of the car. I can't remember if they were a full four-sided box or a three-sided box using the side of the car as the fourth wall (like a Peel P50 petrol tank) but I seem to think the former sounds right. Two pics attached which are the best I have for showing these boxes.
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So now we need to add steering chain slack adjustment criteria to drive train same info needed.
Sounds like you have a steering gear alignment problem, as your shimming of sprocket suggests that you are already aware- and are overtightening the steering chain as compensation.
I just checked and tightened mine. It had only slightly less play than the drive chain. I tightening it to the point where I began feeling substantial enough Resistance through the adjustment bolt to cause me pause to tighten further without factory recommendation.
I was rewarded by this tuning out about half of the violence. So it may become possible that with adding an adjustable steering damper, and perhaps some other tweaks plus slight modification to my driving technique, to acceptably tune if out. But that would leave the cause incurred, and the price for that would likely show show up some where further down the line. Plus it violates my standard. So we are not off the hook yet here.
I won't try the manual up shift into second due to the compromised condition of the last 1/4" of my crankshafts splines, which I have epoxied onto the 2ND gear engagement basket.
The fact that you need to use yours means that 2ND gear clutch issues are likely endemic to the species, and that we should both get entire new clutch assemblies that have been assembled correctly, and not fooled with.
I never found a source. Have you? Tinnerman was recommended, but as far as I could tell, only had a couple parts.
I be included a picture of the greasy steering chain run for others reference. Funny how I needed to see the picture to notice the loose bolt sitting in the grease. I wonder if that came off of what is wrong with my car. Just kidding- that would be too easy.
I see that you are not using your battery box, that appears intact, but without it's Teflon cover showing.
You were right that it was a 3 sided box bonded to the external shell. That is until someone cut the biggest side entirely, and about a third of the smaller sides off of mine.
I am using a smaller battery placed lower down in my original plastic parcel basket to keep the cars c.g. lower.
I spent far too long making a bracket from a strong tie, and tapped threads into it at the same location where the basket retaining bolts were. So I even reused the original bolts and tied it together with a Honda motorcycle rubber strap that I managed to fit nicely.
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Here is my battery box mod.
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The little I do know of these engines is they do not tolerate being towed. Since the Sachs 50 is an easy engine to start, in many cases either kick or pedal, the need to employ such a drastic starting method is frustration due to an inability to adjust the engine to run up well. Add to that the loading placed on the drive system which is counter that when the engine is providing the power and you have continued towing as an excellent way to upset the front of the car. In the same way that rolling roads kill DAF Variomatics.
I also find the lack of specific data on Sachsonette oil details slightly worrying. With a proportion of over 2 million engines being automatic there has to be data available of the net, or via purchase, on this engine. Indeed I seem to recall finding a Scandinavian manual scanned on line for it at one time. There were references to buy data on buy a manual sites too.
Logic says. What was broke when it came? The second stage clutch and shaft. What has been changed? The second stage clutch and shaft for used parts at some point not assembled correctly. The problem is related to the second stage coming in, which has a partially inoperative selection. Thus the most likely bit to not be working is the second stage clutch and shaft.
There is no harm in checking all bearings, alignments and tensions.
The tensioner looks to have been inverted as it shows a hole and a flat edge as if it had worn out once in the other orientation. If so that is evidence of either long usage, being thrashed or towed often. Other condition of the rest of the parts might guide one to which of those options is likeliest. Forcible over use is more likely to have broken something. We already know the clutch was broken in an odd way. So you can see where my money is going on condition. If correct cure might be rather difficult, especially without firm data on which to base the work. Maybe a second car might prove a boon, but it might arrive with its own faults.
Roots car, ignoring the worsening fuel leak, was always easy to start even as the starting system become less effective. Ian is resolving those issues with a service of the starter unit and of the tap. I got it going at several events so Root could drive the car, often at some throttle due to the excess fuel due to the leak. Non of the other Sachs 50 I have had have been hard to get running. Such is their normal reliability I never had cause to play with the clutch systems.
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The great Zardoz has spoken. ::)
OK, I'm going a little grandiose here. But the image of the hovering giant head was too strong to go unmentioned.
Al has always got a most welcome big head for these kinds of things.
However, I haven't fed the big head enough specifically correct data to do the most good yet.
So I have included the , excuse the expression, "exploded view" taken more than a year ago as I was first taking the broken clutch apart.
Looks to me like it is the first gear clutch that shattered.
Other than the crankshaft whose damaged splines occupy only the last 1/4", that are not loaded upon automatic up shifts- I don't know what other damaged shaft you might be referring to.
Sorry if my previous information was too incomplete or misleading.
The smaller diameter basket shaped piece at the end closest to the camera, that is encircled by a spring, is the part whose internal splines were found to be stripped, with consequent damage to lesser degree inflicted upon the last 1/4" of the crankshafts splines.
The big plate at this end has a beveled face at its periphery lined with asbestos like clutch material, and is the alternative mechanism for engaging second gear.
This just in- a scooter specialist just called me to say that a dragging wheel at the rear, via low tire pressure, dragging brake, or bad wheel bearing could also be a source of generating an offset load that could try to torque steer the car.
That would particularly make sense if the loading were cyclical, like a bad bearing jamming up a bit, once per revolution. Could even make sense to be initiated by the possible momentary interlude between the front wheel being powered by first and second gear, as I would expect this type of effect to be most noticable while in an unpowered state. He mentioned all this because he said that side car set ups run similar off set loads, and are particularly prone to episodes of tank slapping.
So I'll throw a block under the rear axle and spin the tires to check for resistance after checking the tire pressures.
Admittedly quite a long shot.
But almost easier to check than to argue about.
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Here is an alternate view that simplifies the arrangement of major clutch components.
You should be able to see the totally stripped inner splines of the peripherily notched basket like piece on the near end, that sat at the tip of the crankshaft.
I used metal filled epoxy on a replacement piece to partially compensate for the damaged splines at the end of the crank, but still do not intend to use the manual over ride engagement of second gear mechanism that is the only initiator of an effect that depends on this connection.
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Mr Spock meets Zardoz. Hmm, interesting.
I was looking at logic there, If backed by evidence there might be answers. If the questions have been answered then move on. It is only by illumination that the source of the problem can be found. So the next idea is as good as the last, unless someone has had a previous issue the same.
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No, I'm not taking a big old TV appliance to the dump.
That is my Minicomtesse having survived the rigors of it's 370 mile excursion to Monterey.
Good news is that not only have I successfully recreated the pedal drive, but the horrific shaking during transmission shifting is now reduced by 80% or so to a nearly acceptable and brief shudder.
Proper tire pressures plus balancing the front wheel/ tire, or maybe just re breaking itself in after reclocking / a different indexing of the first and second gear clutches on the crankshaft splines relative to one another?
I don't even know if that last proposed explanation entirely makes sense.
However I am glad that it has ocurred in time for the Concourse DE Lemons tommarrow morning.
I'll let you know how it goes.
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This just in....Mincomtesse takes top honors ;D
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LeMons 24 howers. How does this work? How does it go backwards? How can it so many wheels? How........ Just accept is a slightly sour taste but refreshing. Its the Lemon to some over restored Gin.
I say, awfully well done, old fruit. Top hole, what!
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Here is an alternate view that simplifies the arrangement of major clutch components.
You should be able to see the totally stripped inner splines of the peripherily notched basket like piece on the near end, that sat at the tip of the crankshaft.
I used metal filled epoxy on a replacement piece to partially compensate for the damaged splines at the end of the crank, but still do not intend to use the manual over ride engagement of second gear mechanism that is the only initiator of an effect that depends on this connection.
Is this the right sort of thing?
http://www.ebay.fr/itm/SACHS-NOS-Saxonette-50-Clutch-1st-Gear-Arctic-Cat-Coleman-Mini-Bike-Vintage-/121416746452?ssPageName=ADME:B:SS:GB:3160
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I reckon so. Same as the one the other geezer had with the Snowtrak thingamabob I put you on to.
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Thanks Barry.
It appears that we both ran across the fact that the Saxonette drive train was also used in the Fox Sundowner minibike, and Artic Cat smowmobiles that were sold in North America. This seller has some good NOS first and second gear clutches to offer, but nowhere other than by purchasing a lightly used complete 2 speed clutch unit was I able to replace the peripherly noched, and internally splined basket like piece shown in the accompanying picture.
In the Minicomtesse this piece allows a manual over ride engagement of the automatic engagement of the second gear clutch. I do not know if this feature was available on the mini bike or snowmobile, but do not intend to use it for upshifting, as unlike Stuarts experience with his Comtesse- this one does now upshift automatically. I also will use jumper cables if the battery runs flat, as further stripping the crankshaft's most distal splines (pictured) that engage this piece is a risk better avoided.
At any rate, I am finally a happy camper, as my Comtesse went from the shakes of death to idling, shifting and driving well enough for 20 minutes in line to pick up the highest award at the Concourse de Le Mons. :)
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Thanks Steven.
I think I would need to dismantle the set-up myself to fully understand what's going on.
My Flipper has a saxonette two speed engine and whilst driving around the garden I could not work out if it was in first or second gear.
It has a cable (with no operating lever attached) which enters the engine - see photo.
I used some Mole gripps to operate the cable but couldn't work out what it did.
It seems it may be a way of keeping the engine in first gear rather than a device for forcing it to change up to second?
https://www.dropbox.com/s/l5iypbfabfn7t7d/P1060765.wmv?dl=0
https://www.dropbox.com/s/6d3idjj8opoew5y/P1060460.MOV?dl=0
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Holding first makes sense for descending a steep hill, etc. DAF had the same ability, in their case holding the cones in place.
Yet to really test out the efficiency of the drive on the Shopper, but it is a very similar unit. The rear wheel. tyre, looks a bit wonky so I might have to have that off. Beginning to be a Sachs Saxonette Auto fanciers club!
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Thanks Steven.
My Flipper has a saxonette two speed engine and whilst driving around the garden I could not work out if it was in first or second gear.
It has a cable (with no operating lever attached) which enters the engine - see photo.
I used some Mole gripps to operate the cable but couldn't work out what it did.
It seems it may be a way of keeping the engine in first gear rather than a device for forcing it to change into second.
If it accelerates well from a standing start, you are likely in first gear.
The change to second would be obvious, even if not accompanied by the "shake of death".
If you are indeed in first gear and pulling on the stock rubber lawn mower type pull handle has no effect- then your clutch / 2 speed tranny unit is probably suffering from a deranged 2ND gear clutch. On mine, it was the first gear clutch that had exploded.
Although it may seem reasonably useful to have a way to downshift into first gear for descending hills, I consider it highly unlikely that a set up that looks identical to my Comtesses' s could be made to work on first gear rather than second. See pic for view of non intuitive path of cable induced and lever transferred push onto thin bevelled strip located as a secondary frictional area for second gear engagement.
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The Saxonette in the Shopper now runs well, needed the float cleaned as it weighed to much with accretions on it. I see how it works now. The valve is in the lid. Should be possible to use paste to lap these together into a fluid proof seating as it is all accessible. Even make a small bow spinner to make it easier, like lighting Ray Mears.
The Shopper changed beautifully into second as it left under its own power to go to the local show, piloted by Andrew. I will see him again at 5 pm with reports.