RUMCars Forum
General Category => Unusual Microcar Discussion => Topic started by: AndyL on January 02, 2015, 05:11:37 PM
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Happened to see these two steering worms on ebay. What I found interesting is that the thread style is different, with one having a v-style thread and the other a square thread profile. I am guessing the square thread was the later profile which would lower friction a bit
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Hi Andy. MIne is a 1959 car and has the V profile steering worm but I was told the square cut thread is better so I managed to get hold of one along with its matching nut last year. I still havnt got around to fitting it. I don't know if the square cut ones are latter but it will be interesting to see if it makes any difference in the feel of the steering.
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In theory a square thread for the same lead angle should give about 15-20% less friction than a V-thread.
I'm pretty sure replacing the silentbloc bushes in the steering linkages with plastic polyurethane items would help a lot too. Greg Hahs does a kit, but it's far from cheap.
I remember years ago foolishly agreeing to change the silent blocks on the lower front suspension arms of a members car. Club had got a bad batch and lots of them were failing. I got a phone call from someone local after the IOC published members details. He asked if I could help, although I soon found out that it really meant fix my car because I don't have a clue!
The chaps entire tool kit seemed to consist of a Black and Decker electric screwdriver. I did fix his car, which was far from an easy task as it involved stripping the car suspension apart in a unelectrified lock-up in the wintertime, plus the club were out of stock on the silentblocks.
The chap was supposed to be there to assist, but always seemed to be called away to an urgent meeting whenever I went around. ::)
I'm older and wiser now.
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Yes, I changed all my silentblocks for new when I got the car but next time around I think I will use rod ends on the link/track rod and polyurethane bushes everywhere else.
I do wonder why BMW use an acme thread on the steering worm in the first place. I guess a square worm may be harder or more expensive to produce.
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The V-thread may have been an attempt to cut down or remove shimmying caused by the single rod actuation of the steering mechanism. That's eliminated with the fitting of a steering damper, but not all cars had one fitted, mine include, although the bracket on the chassis is there for one to be added later. Was probably an optional extra, and shouldn't really be needed until the steering developed some wear and tear
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Mine has never suffered with the shakes and I dont have a steering damper. I wonder if my radial tyres help in that area? Although I replaced all the silent blocks and the front shaft bronze bushes I think I need to do the outer bush again. I think I reamed a little too much material out and there is some play there now. I pump it full of grease and it firms up but only for a few hundred miles. What tyres are you running on?
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My car isn't roadworthy yet, still being rebuilt.
The car still has its original Dunlop goldseal tyres, although they're knackered.
I will probably go for Falken radials when I get to that stage, Terry Parkin runs those and says they fit well on the rims and don't require spacers to clear the shock/spring towers.
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Terry is correct, that's what I'm running on, excellent tyres and not too dear either.
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I think the original crossplies look more appropriate as they sit on the rim better, however if you intend to really use the car I think radials are a much better option.
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Got my steering box top off today, I have the square style thread on my car. So interesting, I think they fitted whatever they had available.
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Next job is to pop the steering wheel of the shaft. Going to make a puller, and think a bit of heat may help. Anyone got any good tips to pass on?
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Only that tension, plus shock from a mallet, is more efficient than whanging on mega pressure to break the taper. But you know that. The tool made will fit a number of other vehicles, so its handy. I have an original Goggo one, made out of parts of the rear shaft puller set as intended, very neat. So far it only did not fit the Schmitt, which has an awkward and offset angle. Really you need both a nut and handlebar puller to make a neat job of that installation. I have the puller available, now I have Russell's stock, but its a bit of a sledge hammer to crack a nut on anything else, £30.
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Next job is to pop the steering wheel of the shaft. Going to make a puller, and think a bit of heat may help. Anyone got any good tips to pass on?
I gave up on pullers and whacking it with a mallet after I discovered that a small 12-ton press works great.
The wheel and shaft fit nicely into the confines of the press, then it is a simple matter of pressing the shaft out, rather than pulling the wheel off.
The most stubborn wheels just pop off with very little effort, no heat needed, and certainly no damage. (unless you screw it up somehow...)
I bought a very small 12 ton press 10 years ago for around $100USD. It takes up very little room and I have used it for all sorts of things over the years.
If you don't have a press, find a friend that does. That's what friends are for. ;)
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I know exactly what you're talking about, but I don't really have the space for a tool like that- I've seen the size of the garages you folks have in the US.
I do have a couple of small bottle jacks, not 12 ton, but probably good for a ton at least, I would think that would suffice to pull the wheel off, so I could put something together that will get the job done.
There is also a hydraulic press I can access at work, so I might give that a go. I take it you pressed against the bottom of the aluminium hub?
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Tight on the hub and protect the threads on the column. If pressure is not square and controlled it can either turn or bell the end of the shaft. Most shafts are made of surprisingly soft metal. If anything touches the plasticised and caste in parts the damage is done before you notice. So be certain the area is clear. With a correct puller I have never had a failure other than when Mr Botch has stepped forward. Like welding the wheel on etc.
Hydraulic press is really useful but its the box of handy scrap used as dollies that gets in the way! I have about 3 bakers trays of them, now I have manufacturing tooling. Comes with the territory.
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Easy enouh for me to make a custom mandrel so that it locates accurately in the centre of the steering column- got a decent sized lathe and know how to use it.
Took me a morning to get the pesky swivel bolt off the steering column which bolts to the dashboard.
I know it'll all go back together a lot easier than it came apart, all the bits will be greased for a start!
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Its good to hear you have the acme cut steering worm, they all say its the better of the two.
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So meep meep to the coyote version it is!
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I know exactly what you're talking about, but I don't really have the space for a tool like that- I've seen the size of the garages you folks have in the US.
There is also a hydraulic press I can access at work, so I might give that a go. I take it you pressed against the bottom of the aluminium hub?
The press I am talking about is rather small, between 4-5 ft tall and 2 ft wide, 2ft deep max:
http://www.harborfreight.com/12-ton-shop-press-33497.html (http://www.harborfreight.com/12-ton-shop-press-33497.html)
You could probably rig up something with a bottle jack just for this if you wanted to, then dismantle it after the wheel is freed up.
If go the press route, have the assembly resting on blocking from either side with the bottom of the wheel resting on the blocking and the shaft passing through and hanging down.
Leave the nut on the top of shaft for now and press down on that. The wheel stays stationary and the shaft is then pushed down.
Leaving the nut in place serves 2 purposes:
1: When it frees up, it prevents the shaft from dropping through and clunking on the floor
2: It prevents the threads on the top of the shaft from mushrooming or deforming due to the pressure of the press.
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Yes that's how I thought it would look, very similar to the one at work. Really haven't got the space for that. I'll make something up or use the one work.
Question, did you make a cradle to support the underside of the wheel? The aluminium steering shaft bushing will only move down the shaft about quarter of an inch or so before it jams up, so not much clearance underneath. The wheel hub is soft aluminium so I don't want to damage it, thinking of maybe turning up a cradle from some hardwood.
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Question, did you make a cradle to support the underside of the wheel? The aluminium steering shaft bushing will only move down the shaft about quarter of an inch or so before it jams up, so not much clearance underneath.
hmmm, that's right, the aluminum cast piece has to be removed from above and the wheel is in the way.
It has been awhile since I did this.
Regardless, I used the pair of cast iron blocks with notches (you can see them on the pic of the press if you click the pic) to support the wheel from the hub while letting the shaft pass through. I probably spanned the aluminum piece and then put some chunks of 1/4" steel bar in there to finish the span so that the blocking supported the wheel hub only before pressing.
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Okey dokey. So basically a split hub supporting the underneath, it seems I'm going about things the right way then.
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Got my wheel off okay. I used a large two leg puller in the end, with a custom split plate that bolted together underneath the wheel.
I used a bit of heat to expand the aluminium hub, but nothing drastic. Came off with a sudden pop. :)
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Well done Andy. I have only this week put mine on, left job almost until last in case in had to come off again and ruin the paint!
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I took my steering/pedal box off today.
Like everything else on this little critter, it's jammed up- the pedals move fine, but the bolt/shaft that runs through them all is stuck firm inside the aluminium housing.
I have a good spare, which I intend to use, as it's in better nick anyway. However interestingly I found there was a variation in the two aluminium castings. The one on my car had the rod completely enclosed inside the aluminium housing, whereas my spare had it exposed once it went into the aperture for the steering gear.
Not sure why or when the design was changed, but just another little mystery thrown up.
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(http://img.photobucket.com/albums/v293/subculture84/steering%20boxes_zpsuhv0ozhh.jpg) (http://smg.photobucket.com/user/subculture84/media/steering%20boxes_zpsuhv0ozhh.jpg.html)
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I would imagine the one with the partially exposed shaft would be less prone to seize up and could share a little grease that is packed around the worm and nut. Other than that I cant think of any reason why they would have made the two types. I wonder which one came first?
I cant say I noticed which type my car has when I removed that part.
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Looking at some period photographs, it seems the box with the exposed shaft is more in keeping a with a sliding window car, and the other unit was fitted on earlier cars like the bubble window vehicles.
As so many people say, is there such a thing as an original Isetta? They seemed to throw on whatever they could lay their mitts on. Does make me laugh though, you just don't get those sort of idiosyncrasies with modern cars.
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but in 60 years time will we all be discussing the merits of a '14 Skoda Octavia over a '64 Audi - I doubt it
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In 60 years time, it's doubtful 'we' will be discussing anything at all! ;D
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;D
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Ah, Those days before lead free feathers.