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Post by valhalla on Jun 16, 2021 23:21:11 GMT 1
Having finally had enough of trying to do steering alignments on the 2-post ramps - lifting in the air to release tie-rods, then dropping down again on the floor to do the alignment check and adjustment, with all the attendant problems of wheels grabbing on the floor - I made some skid plates today. These are 25cm x25cm glass-filled thermoplastic composite raw sheet, which I cut-out with a slitting disc on the grinder, then trimmed with a knife. I have four of these sheets, and each pair is sandwiched with a dollop of silicon grease - nothing else to hold them together. They work brilliantly, and so far seem to not attract too much grit between them when they are sliding apart. I wish I had made these a few years ago, as it only took me 30mins to do. However, has anyone got any experience of commercial skid-plates for use free-standing on the floor? My turning plates for the 4-post ramps are rusted to oblivion, so no use there, but I could do with some units that allow the wheel to slide in all directions parallel to the floor, with good bearings, as I want to make a shaker-rig to find suspension faults?
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Post by studabear on Jun 16, 2021 23:27:22 GMT 1
back before most of our centres had Hunter hawk eye dedicated lifts we mainly used Super tracker, the turn plates were a concaved metal plate, bit like a bowl, these sat on another flat plate or the ramp bed, they worked just fine.
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Post by studabear on Jun 16, 2021 23:31:10 GMT 1
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remmington
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Post by remmington on Jun 17, 2021 6:26:25 GMT 1
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Post by valhalla on Jun 17, 2021 23:09:19 GMT 1
This is exactly what I need to make - it hits the nail on the head. I have been struggling for ages to get under cars to release tie-rods and make adjustments, and have always had to revert to the 4-post ramps for the majority of tracking work.
Somewhere I have a couple of homemade ramps that someone gave me a while back - I reckon they could be a good start. I think I could manage with my homemade skid-plates for a while on this sort of thing, but may need to revert to some proper dishes like Stu linked above for lots of turning, as the silicon grease on my plates may not stay thick enough with that sort of abuse.
What I also had in mind, and this would definitely have to be down on the floor, is a floating pair of plates that allows the front/rear axle to be shaken to within an inch of its life, to match what I'm up against with MoT rigs. I definitely have to up the game on this front, as I'm missing too much with the wheels dangling at the moment. An illustration of this is my V70 TDI that I was working-on yesterday; the inboard steering tie-rod rose-joint only has play on the nearside when the wheel is in its normal attitude - no play exists with the wheel dangling.
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remmington
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Post by remmington on Jun 18, 2021 6:46:35 GMT 1
This is exactly what I need to make - it hits the nail on the head. I have been struggling for ages to get under cars to release tie-rods and make adjustments, and have always had to revert to the 4-post ramps for the majority of tracking work. Somewhere I have a couple of homemade ramps that someone gave me a while back - I reckon they could be a good start. I think I could manage with my homemade skid-plates for a while on this sort of thing, but may need to revert to some proper dishes like Stu linked above for lots of turning, as the silicon grease on my plates may not stay thick enough with that sort of abuse. What I also had in mind, and this would definitely have to be down on the floor, is a floating pair of plates that allows the front/rear axle to be shaken to within an inch of its life, to match what I'm up against with MoT rigs. I definitely have to up the game on this front, as I'm missing too much with the wheels dangling at the moment. An illustration of this is my V70 TDI that I was working-on yesterday; the inboard steering tie-rod rose-joint only has play on the nearside when the wheel is in its normal attitude - no play exists with the wheel dangling.
These ramps need to be fairly long - as when you drop a car down on them - you need to push the car backwards and forwards to get the camber angle back (from where the wheels were hanging down on a two poster ramp). ---------------------------- It is just easier to find suspension play with the weight on the wheels on a fourposter or over a pit. It just is... I am gonna struggle to explain the following but I will try. Imagine a 12" length of scaffolding tube - weld a big 1/2 drive socket to one end (AF one you are never gonna use again) - then attached a normal 18" breaker bar to it at 90 degrees. Put tube under wheel/tyre in question - drop weight of car on tube - wiggle breaker bar like a shacker table www.youtube.com/watch?v=dzrOvgkMxKgwww.ebay.co.uk/itm/SYKES-PICKAVANT-08085000-SUSPENSION-WEAR-INDICATOR-/272218196342I have a 12" big block of wood with a groove in the top - to drop the pipe onto - it gives me more height to look under car - when working off a two post ramp - plus you get better access to put the breaker bar in the 1/2 socket - from bottom or top if you know what I am poorly trying to explain?If you make the pipe long enough - my Father used to rest it between two axle stands - this is not as good as a block of wood - as you can tip the axle stands to one side when you lower the car onto the pipe - Dads set up was primitive to be honest - he used 18" stilsons on the pipe
I have thought about - making up a purpose made "frame" - pipe - two end sleeves so pipe can rotate - with a frame welded up to the sleeves. Maybe spring retractable castors on it that move up when the wieght of the car falls on the pipe - there is another benefit of getting the "pipe" higher - you get to get hold of the breaker bar - the sykes tool above layed out on the floor or ramp - is jammed like an L on the floor and you can't get your hand round the handle to use it |
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Post by voicey on Jun 18, 2021 7:45:41 GMT 1
Those tables are crazy money. I don't think I paid much more for brand new my 4 post geo lift with turntables, rear slip plates and a rolling jack! |
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remmington
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Post by remmington on Jun 18, 2021 7:59:21 GMT 1
Those tables are crazy money. I don't think I paid much more for brand new my 4 post geo lift with turntables, rear slip plates and a rolling jack! I made mine (tables) - I just made them too heavy (everything I make it too heavy).  |
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remmington
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Post by remmington on Jun 18, 2021 14:01:22 GMT 1
Valhalla - see picture of pipe thing I made up.
Rusky reckons it works OK on bigger 5ton axles stands (better than the lump of wood I use!).
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Post by Joepublic on Jun 18, 2021 18:25:13 GMT 1
The mot place I use have a pit, they have round thin plates inside an oblong plate fixed to the floor, these are folded over to keep the plates from dislocating allowing the plates to turn with the front wheels and elongate as the track widens on droop
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Post by valhalla on Jun 18, 2021 22:59:53 GMT 1
Valhalla - see picture of pipe thing I made up. Rusky reckons it works OK on bigger 5ton axles stands (better than the lump of wood I use!). I see from your description above about these - they are a much more clever idea that I had been thinking-of up to now. I have loads of scaf-tube offcuts, and doing the forcing by turning a tube under the tyre is a much easier way of supporting the wheel than trying to make floating plates.
I think I might even be able to go a little further, but it would only work with some careful design;
I am going to see if it is possible to make two tubes parallel to each other, and support the wheel/tyre on a plate that is balanced across them. The reason for doing this is that it doesn't matter if the support structure is slightly off-centre, but mainly it would allow the whole rig to be used to propel the wheel back/forwards if the service brake was applied, which might find rear-void-bush compliance that may not be quite so obvious if the wheel is dragged out in camber.
What I am also thinking of doing, which might just be silly as a first-stage trial (I like your use of a breaker-bar!) is to substitute the breaker bar for an impact-driver. The inertias are all wrong, and it might just be too much for the welding (my welding....  ), but this would hammer the suspension in a remote way whilst I looked for play.
Now the clever bit - I'm thinking about fitting an adapter for a Pico NVH transducer to the plate, then measuring the motion on the plate. A sinusoidal signal would indicate an elastic compliance in bushes and suspension arms = OK, whereas a spikey signal would indicate a free-play and then a sudden jolt stop on each cycle. With a library of known good and bad suspensions, I reckon it would soon be possible to declare a suspension OK or not just from the transducer signal.
You have got my creative juices flowing now - I'm on fire....  |
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Post by valhalla on Jun 18, 2021 23:07:34 GMT 1
These ramps need to be fairly long - as when you drop a car down on them - you need to push the car backwards and forwards to get the camber angle back (from where the wheels were hanging down on a two poster ramp). That is the good thing about the skid-plates I have made so far - they have such low friction in either lateral or longitudinal direction, they don't upset the camber when the suspension comes back down to its settled height; they just let the wheel slide out as it would if the car was rolled.
Clearly....there is a danger when doing this, as if the car is not constrained to stay on the 2-poster jack-pads, there is a chance it could slide off the ramps blocks under the skid-plates. I'm guessing that it would make my day if that happened..... I have only tried my skid plates on the concrete under the 2-poster, but I can easily push a Volvo V70 sideways with my hand pressure on the outer wing, so that is what I'm up against - I need to make some constraining lips around the plates like JoePublic mentions above.
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Post by valhalla on Jun 18, 2021 23:13:45 GMT 1
Right.....I know the direction I need to take on these skid units. I have just thought about what I typed above, and the obvious thing to use as the roller unit is a fairlead unit from a winch setup. I have a few around as spares, new ones with good bearings.
I will just have the main parallel rollers proud to a plate, and that plate will be bigger in area than the fairlead unit, but with a lip welded around the lower edge - to constrain the motion should the whole car start to slide sideways/forwards off the unit.
Prototyping to start this weekend.....  |
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remmington
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Post by remmington on Jun 19, 2021 6:19:12 GMT 1
Right.....I know the direction I need to take on these skid units. I have just thought about what I typed above, and the obvious thing to use as the roller unit is a fairlead unit from a winch setup. I have a few around as spares, new ones with good bearings. I will just have the main parallel rollers proud to a plate, and that plate will be bigger in area than the fairlead unit, but with a lip welded around the lower edge - to constrain the motion should the whole car start to slide sideways/forwards off the unit. Prototyping to start this weekend..... I like buying new shiney tools (I think all mechanics like shiney tools). But I really love making things for the garage - always have done. Valhalla is gonna come up with something better than I am capable of producing here. ---------------------- Not forgot the "mod". Valhalla came up for pressure brake bleeder caps - "Genius"  |
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remmington
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Post by remmington on Jun 19, 2021 6:38:56 GMT 1
Valhalla - see picture of pipe thing I made up. Rusky reckons it works OK on bigger 5ton axles stands (better than the lump of wood I use!). I see from your description above about these - they are a much more clever idea that I had been thinking-of up to now. I have loads of scaf-tube offcuts, and doing the forcing by turning a tube under the tyre is a much easier way of supporting the wheel than trying to make floating plates. I think I might even be able to go a little further, but it would only work with some careful design; I am going to see if it is possible to make two tubes parallel to each other, and support the wheel/tyre on a plate that is balanced across them. The reason for doing this is that it doesn't matter if the support structure is slightly off-centre, but mainly it would allow the whole rig to be used to propel the wheel back/forwards if the service brake was applied, which might find rear-void-bush compliance that may not be quite so obvious if the wheel is dragged out in camber. What I am also thinking of doing, which might just be silly as a first-stage trial (I like your use of a breaker-bar!) is to substitute the breaker bar for an impact-driver. The inertias are all wrong, and it might just be too much for the welding (my welding.... ), but this would hammer the suspension in a remote way whilst I looked for play. Now the clever bit - I'm thinking about fitting an adapter for a Pico NVH transducer to the plate, then measuring the motion on the plate. A sinusoidal signal would indicate an elastic compliance in bushes and suspension arms = OK, whereas a spikey signal would indicate a free-play and then a sudden jolt stop on each cycle. With a library of known good and bad suspensions, I reckon it would soon be possible to declare a suspension OK or not just from the transducer signal. You have got my creative juices flowing now - I'm on fire.... 1. If you are gonna use a pico/transducer - air impact wrench would give a known value every cycle (could not reproduce by hand). 2. You could remote switch an air wrench (valve in hose). But you will only get one directional (breaker bar powers both ways - so do MOT shacker plates - I have had a good look at these - as I thought of making one). 3. But I don't think you would get enough degrees of rotation with an air impact wrench to find play in anything (just a load of vibration).
We do hold the brake pedal down and use out scaffolding pipe in the other plane to find rear wishbone play.You have got me thinking here too - the easy you make these things to use - the more effective they are! To be honest thou - the way to go is - air shaker plates on a full deck/full height ramp (single operator MOT design). Finding a working solution for a two post ramp with the weight off the wheels - is not easy - but I sure what ever you make needs to be higher - so you can get under the vehicle to see/feel the play. |
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), but this would hammer the suspension in a remote way whilst I looked for play.
