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Post by Joepublic on Jun 19, 2021 8:52:00 GMT 1
The vibration unit from a whacker plate turned slowly would create good shake?
Mounted on an old pallet truck would help with mobility?
Used with 3 lightweight stacking boxes for the other 3 tyres to sit on so the whole lot could be stored on said pallet truck when not in use?
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Post by Rhubarb on Jun 19, 2021 11:37:18 GMT 1
I wonder if working like this would leave any marks anywhere?
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Post by valhalla on Jun 20, 2021 0:36:51 GMT 1
I think the main thing here is that I don't create something that is going to break the ramps, or drop the car off the ramps.
There are "lessons to be learned" from the MoT rigs - make sure that the shaking frequencies are matched to the car's suspension, and not the ramp posts! AKA the NI fiasco with the unified rigs over there that all cracked in exactly the same way........
For the shaking purposes (suspension testing) I'm proposing to prototype this on the floor, and see how much can be gleaned with the vehicle at floor height with the wheels loaded down onto the concrete. It is a pain to see what is going on like this, but I suspect much safer.....and after all, this is what extendable inspection mirrors and cameras are for. This devoids the 2-post ramps of any of the shaking forces going-on, as the ramp arms only need to lift the car away to remove the units under the wheels. Also, I suspect that only a pair of shakers/plates would be needed, because the intended height of these should not upset the pitch of the car too badly when it is sat down on the floor.
The wheel alignment aspect of all of this can be done in the air with ramp units under the 4 wheels exactly as you suggest above, and just needs a safe way of removing all friction between one or both wheels on a given axle to the ramp on which it sits. If the wheel is free to rotate whilst the 2-post arms are lowered, then the only degree of freedom needed should be the lateral plane, meaning that the double-roller set-up might just be able to be re-purposed in that way, whilst still giving some degree of limitation in lateral motion (so the car doesn't just slide sideways off the mini-ramps).
I think you are correct about the impact forces needing both directions, not the single direction from an impact gun. I had my doubts last night when I was typing away, but I still like the idea of a reciprocating turning device, rather than just going in there with a linear device like a Kango hammer - which I had several old spares knocking about the workshop somewhere from several years ago...... A turning device sounds a bit more controlled than a Kango sticking out the side of everything.
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Post by valhalla on Jun 20, 2021 23:35:31 GMT 1
Well, I failed at the first hurdle today - I cannot find the fairleads that I know I still have (somewhere);
I did manage to tidy the workshop and machine-shed on the way to finding the fairleads, and I think I can remember now where they might be....
During the tidying-up, in the area of the workshop where these units should have been - with all the lifting/towing metalwork - I found a set of brand-new turning-plates like Stu posted above. I reckon they must have come with the laser-tracking tool, but heaven only knows why they were there. I cannot remember them ever arriving or being there before.....
Time for a really good tidy-up now, me thinks.....
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Post by Joepublic on Jun 21, 2021 10:10:58 GMT 1
Been for an mot today (pass, advisory for out of round rear tyres) and took pics of the plates
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Post by valhalla on Jul 11, 2021 0:55:20 GMT 1
I have cheated a bit here, and went and bought one of those "paint-roller" sort of tools that was linked and mentioned above. I still intend to produce the shaker rig, but I have found that getting the bearings right is not going to be as trivial as I had hoped.
The main issue I have seen, so far, is that the need to lift the vehicle up to get it on a rig is not so good for finding problems. The wheels drop down out of the wheelarches, and everything relaxes in a way that seems to hide some of the issues, so you are forced to use skid-plates like I have already fabricated (two sheets of plastic with silicon grease sandwiched between) to get the whole suspension back where it should be. Except you cannot do that on a lot of these air-suspension monsters that I often have through my doors - once you disconnect the battery, you really do not want to be reconnecting it until every wheel is back on level ground.
The advantage of the "paint-roller" tool is that you can lock it with the breaker-bar, and just drive the vehicle onto it, which has minimal chance of disrupting the suspension and losing the evidence of what might be going wrong. The forces you can impart with this tool are incredible with a 1.5m breaker, even on rough concrete flooring. So I'm thinking that something that combines a few advantages from different methods is going to be the way forward here. A fairlead unit with mini-ramps all around it, and a way of locking the "table" to get the vehicle on and off safely, is now what I'm considering.
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remmington
Apprentice
Owns Spark Eroder
Posts: 4,971
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Post by remmington on Jul 11, 2021 3:05:42 GMT 1
I have cheated a bit here, and went and bought one of those "paint-roller" sort of tools that was linked and mentioned above. I still intend to produce the shaker rig, but I have found that getting the bearings right is not going to be as trivial as I had hoped.
The main issue I have seen, so far, is that the need to lift the vehicle up to get it on a rig is not so good for finding problems. The wheels drop down out of the wheelarches, and everything relaxes in a way that seems to hide some of the issues, so you are forced to use skid-plates like I have already fabricated (two sheets of plastic with silicon grease sandwiched between) to get the whole suspension back where it should be. Except you cannot do that on a lot of these air-suspension monsters that I often have through my doors - once you disconnect the battery, you really do not want to be reconnecting it until every wheel is back on level ground. The advantage of the "paint-roller" tool is that you can lock it with the breaker-bar, and just drive the vehicle onto it, which has minimal chance of disrupting the suspension and losing the evidence of what might be going wrong. The forces you can impart with this tool are incredible with a 1.5m breaker, even on rough concrete flooring. So I'm thinking that something that combines a few advantages from different methods is going to be the way forward here. A fairlead unit with mini-ramps all around it, and a way of locking the "table" to get the vehicle on and off safely, is now what I'm considering.
The "paint roller" thing is a simple solution. It does work. Also it is very low tech. As you said. The force you can get thru two planes is very high. I was using mine on the floor this week with an early 2003 DAF LF horse box. I found all sorts of horrors on the front suspension with ease.
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