madmog
Club Retro Rides Member
Posts: 1,153
Club RR Member Number: 46
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Sept 30, 2021 20:46:33 GMT
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I've fitted air suspension on my W114. (Thread here ) When it's low I need to have the wheels straight or they will hit and damage the wing and/or tyre. Rather than poking my head out of the window I'm going to fit something in the car so I know the wheels are straight enough to lower safely. Not when driving but when stationery obviously. I can think of three options: 1) micro-switch(es) connecting to an LED triggered by the steering arms. Eg a green LED light in the cockpit that lights when the wheels are within the safe range as indicated by the steering arm only pushing the switch within that range. Would probably have two in series, so if one switch fails on somehow the circuit would still not give a false positive. What type of switches are suitable for engine bay life? 2) cheap camera under the car - seems excessive and delay in switching the radio to correct camera or permanent screen which seems daft also. 3) Some modern cars' rear camera screens have aiming lines that move with the position of the steering wheel, showing where you will end up for a given steering wheel position. How do these work and are they easy to hack? Is it something like a rheostat? Thanks |
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93fxdl
Posted a lot
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Posts: 2,000
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Sept 30, 2021 21:32:56 GMT
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How about a mark on the steering wheel?
Ttfn Glenn
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madmog
Club Retro Rides Member
Posts: 1,153
Club RR Member Number: 46
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Sept 30, 2021 21:39:05 GMT
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Steering wheel turns several full,revolutions lock to lock. Otherwise 'wheel straight ahead' would be good enough.
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Sept 30, 2021 22:13:39 GMT
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How about a DIY steering angle kit? To be honest this seem very over-priced, but it gives you the idea and I'm sure you could come up with something cheaper. |
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I could imagine how you could use some kind of switch on the track rod - have a "bump" on the track rod that pushes in a momentary contact switch while it's in the position you want, and as soon as you move either left or right the bump moves and the switch releases. Have one on each side for some fault tolerance.
Now I think a bit more, the position of the switch would need careful thought to take into account up/down movement of the track rod as the suspension moves. The other way would be to modify the steering rack, but that's probably quite expensive.
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madmog
Club Retro Rides Member
Posts: 1,153
Club RR Member Number: 46
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Thanks guys. It's actually a steering box but same still applies, finding a location which is less exposed to movement and the elements. There's actually a steering damper - a horizantal shock absorber which is a bit out of the way and doesn't move up and down with the suspension. The question remains what sort of switches or micro switches are somewhat rugged? I guess I can always encase something in epoxy.
I think the microswitch idea is the way to go as it can be done for < £10 for a LED or 3 and switch. Could even do a traffic light thing with 5 LEDs in a row somewhere discreet. left red is no, too far left, left amber LED close, on the left, green for okay, mirrored on the right.
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I'd still go with a steering angle sensor, particularly if you want a "almost, not quite" type display. Plus, it can be mounted under the dash and not be subjected to the heat, dirt and moisture under the bonnet.
You could simplify the idea I posted previously; get a small rubber roller - an R/C car wheel & tyre or a small rubber castor. Drill the center to suit the shaft of a potentiometer and mount the wheel on the potentiometer shaft, and the potentiometer on a bracket that keeps the wheel in contact with the car steering shaft.
You could then use a small voltage gauge to display the position of the steering.
OK, might cost more like £20 than £10, but it would be much more reliable and accurate.
Another idea might be to get a linear potentiometer and mount it in parallel with the steering damper, and again use a small volt gauge to display the position.
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I'd go for a single switch in the straight ahead position, might be able to fit a cam and switch on the back of the pitman arm, if you wanted to be clever you could wire it into the air suspension so it will only lower with the switch closed.
Perhaps look at a reversing light switch, quite a few cars in the 70's had external ones.
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Last Edit: Oct 1, 2021 14:59:13 GMT by kevins
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slater
Club Retro Rides Member
Posts: 6,390
Club RR Member Number: 78
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Reed switches like you would use on a pneumatic cylinder. Totally sealed (apart from the plug) they are actuated by magnets so you would have to attach a magnet somwhere and make a bracket to hold the switch. Would think the arm off the steering box is the obvious choice (no worrying about suspension movment etc..)
Column mounted sensors are a bit of a fiddle to make work when you have many turns lock to lock. You can gear them down but you've still got to do somthing with the output where as a switch is a switch. Most will be 24v but should work on 12 I should think.
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TessierAshpool
Club Retro Rides Member
Posts: 507
Club RR Member Number: 168
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Unipolar digital Hall effect sensor to detect when the steering box arm passes in front of it?
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Drive it three feet back and forth and you will know if you have lock on,and your wheel is in the straight ahead position.
Then drop the suspension.
Apologies for stating the obvious ha
Cheers Matt.
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madmog
Club Retro Rides Member
Posts: 1,153
Club RR Member Number: 46
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I'd go for a single switch in the straight ahead position, might be able to fit a cam and switch on the back of the pitman arm, if you wanted to be clever you could wire it into the air suspension so it will only lower with the switch closed. Perhaps look at a reversing light switch, quite a few cars in the 70's had external ones. "if you wanted to be clever you could wire it into the air suspension so it will only lower with the switch closed." I did think of this but don't want the 'brain' being switched on and off as I drive about. It takes a second or two to boot up. |
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madmog
Club Retro Rides Member
Posts: 1,153
Club RR Member Number: 46
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Just picked up a steering angle sensor for £8 off Ebay to have a play with. I suspect it'll be a faff changing the signal so LEDs come on at different voltages but for £8 it'll be fun research
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Or you could go complete stealth - put a couple of relays in the feed to the fuel tank sender and with the flick of a switch, the fuel gauge becomes an analogue wheel position indicator!
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