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Author Topic: Riley Special chassis (Bridget the Riley)  (Read 8457 times)

Seven racer

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Re: Riley Special chassis (Bridget the Riley)
« Reply #135 on: 12 Jan 22, 10:01 am »
Wings may add a bit of weight, but they add loads more style, it looks more complete.

Perhaps attach them with bolts and wing nuts so they detach on those occasions you really want to try hard!

Lots more work, but as a retro fit they can be done at any time in the future, well worth the extra effort.

Peter

synthpunk

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Re: Riley Special chassis (Bridget the Riley)
« Reply #136 on: 29 Jan 22, 07:59 pm »
Quick pic- got a roll of gummed paper tape, and experimentally applied 2 cross ply layers across one side of the top of the tailcone. Sort of works, need to do some cleaning up of the wooden framework to ensure success. Current plan is to cover the buck in several layers of the tape, then lay over some heavy grp mat, once that’s dry peel it off the Paper (or cut it off the mould with a saw/angle grinder) then fill and sand to desired finish before painting.

synthpunk

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Re: Riley Special chassis (Bridget the Riley)
« Reply #137 on: 03 Apr 22, 07:00 pm »
Well, in spite of it snowing on Friday in mid sussex, the weather is generally improving enough, in combination with the later evenings courtesy of BST for me to seriously restart work on Bridget the Riley. First things first though- a massive spring cleaning effort, which has more than doubled my amount of workspace in the shed. You may have noticed that many of the pics so far have been long shots down the chassis, with no landscape, wide angle shots. This is because up till now, the whole thing has been built in a 3.5 foot by 8 foot space between walls of broken guitar amplifiers on either side. Very difficult to sneak down the side of the ck even sideways for a skinny arse like me.

Courtesy of several trips to the local tip, many binbags, and my trusty garden incinerator I now have 8 feet by 10 feet to work in. I’d say there’s enough room to swing a cat but he doesn’t really like it when I play that game so Ive not tested it yet…

Let the madness (re)begin!!

David F-R

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Re: Riley Special chassis (Bridget the Riley)
« Reply #138 on: 04 Apr 22, 08:21 am »
Looking good.
Space is very much at a premium for me too but you seem to have **** it.
I'm not quite as green as I'm cabbage sounding.

synthpunk

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Re: Riley Special chassis (Bridget the Riley)
« Reply #139 on: 07 Apr 22, 07:34 pm »
Need to tidy up the spills and finish the central boss, but anyways- more done on my steering wheel. watched a documentary about the bayeaux tapestry on the bbc whilst wrapping it with string, which took blooming ages and 2 balls of white parcel string… Then mixed up some shellac flakes and meths and put two coats on to seal and secure everything. Nice and grippy, and a pleasing shade of tweedy brown.
« Last Edit: 08 Apr 22, 08:46 am by synthpunk »

synthpunk

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Re: Riley Special chassis (Bridget the Riley)
« Reply #140 on: 07 Apr 22, 07:39 pm »
Cant remember if I mentioned but I decided I wanted a bigger steering wheel than the 13” one I started making, and got lucky with a 15.5” vintage 3 spoke wheel off ‘something or other quite vintage’ that I got off eBay for £10 due to missing the central hub/boss…

Jimr1999

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Re: Riley Special chassis (Bridget the Riley)
« Reply #141 on: 07 Apr 22, 08:12 pm »
Looks pukka, nice job
... You can lead a horse to water, but a pencil must be lead.

synthpunk

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Re: Riley Special chassis (Bridget the Riley)
« Reply #142 on: 29 Apr 22, 07:13 pm »
Ive been tinkering with the rear end, making a cradle/subframe to hold the engine, rear axle and brake callipers all straight and square to each other that will bolt into the aluminium angle parts that are already there, thus creating a fully functional cyclekart drivetrain that just bolts in to the structure ive already got and goes.

That’s Plan A.

Plan B involves the cradle I’m building for plan A, and adding a couple other components, and in return getting a limited amount of suspension for the rear end. It’s a bit wierd and the parts I’ve cut up and shaped are away being welded at the mo so there no photos till next week but I reckon it’ll work. It’s sort of inspired by the 2cv and the mini, in that there’s rubber cones involved. Also speedway bikes and mobilette mopeds because there’s also rubber bands.

The notable feature on the design is that it minimises the unsprung weight by moving the engine to above the ‘pivot point’ of the system, rather than having it sitting on the axle, and also that almost all the weight of the suspension cradle and half the engine is either at or below the height of the axle.

Axle location is via a Watts linkage. Careful placement of this will allow me some control over the roll centre height. Apparently this is a Good Thing.

All this extra effort is because the Riley has NO flex in it, unlike the average steel rail chassis CK, I’m guessing. So I want some flex and twist in there to stop it from just skidding off sideways at every corner like a badly setup scalextric car. An inch or so should be fine. It’s for handling rather than driver comfort.
« Last Edit: 29 Apr 22, 07:16 pm by synthpunk »

Adrian

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Re: Riley Special chassis (Bridget the Riley)
« Reply #143 on: 30 Apr 22, 04:40 pm »
Be careful now, you could be starting a series of discussions on 'suspension'
You need the chassis to be as rigid as possible, always.
Set the front suspension fairly soft......and tell you what, Rhys, tell the man!
'>)
🚗

synthpunk

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Re: Riley Special chassis (Bridget the Riley)
« Reply #144 on: 24 May 22, 11:21 pm »
Ive been meaning to draw a picture, but in between Small child, and the imminent arrival of Another Even Smaller Child, Ive basically not had the time. Actually that’s not true, I did draw a picture but Small Child drew on it with crayons because I left my sketchbook on the sofa. Oops.

Anyways, I got a friend to help me with the welding bits, but I cut up a load of 30mm square 2mm wall tube and got some hanger plates from Gemini and cut it up acceptably square and true. It still needs some capping welds in some places, and gussets and the whole engine mount bits and also a whole load of other stuff but it’s sort of a good visual hint as to where I’m going…. The brake calliper is floating on the axle, but braced at right angles to the engine mount (I might not have explained that correctly but it should be right) and the engine CofG will be probably/hopefully over the pivot point, and yes very much rubber bands, springs, bushings and mounts are all going to be involved somewhere..… as far as my meccano experiments have gone, I think it should work, at least as far as within the fairly limited amount of movement I need/expect from it. It’s not an off road quad, after all.

You can sort of see where there’s space for a Watts Linkage at the front, I’m thinking that I can either have some chunky aluminium tabs welded on to the existing ally plates, or just bolt some steel ones on to mount the chassis side links to…

synthpunk

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Re: Riley Special chassis (Bridget the Riley)
« Reply #145 on: 24 May 22, 11:43 pm »
I’d like to add that this diversion has so far added just 3 kg to the build, and I’m not expecting that to increase that much, by the time it’s done, due to rubber not really being very heavy. Which seems not bad to me. Especially since it should cut the unsprung weight in half as a side effect as well.

The watts linkage pivot is going to be below the axle, which will set the Roll Centre for the back end about 2 inches below the axle height. I have no idea if this is a good thing or not, but I think it might be. Yay meccano.

synthpunk

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Re: Riley Special chassis (Bridget the Riley)
« Reply #146 on: 30 May 22, 01:25 am »
Unexpected Great Leap Forward- I visited my friend and hassled him into doing a pile of tig welding for me, and after he’d finished he sold me a mig welder and a bottle of gas so I’d stop hassling him and leave him alone…. Result!! :c)

Anyways- heres a pic of my rear end.(fnar fnar) I think you’d possible describe it as a leading arm rear suspension. The engine will sit on top of the pivot point at the rear(the rod end), thus minimising the unsprung weight. It’s all just finger tight at the moment whilst I measure up all the spacers I need to make…

synthpunk

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Re: Riley Special chassis (Bridget the Riley)
« Reply #147 on: 30 May 22, 11:46 pm »
Ive added the wheels & engine and loaded it down to about where it’ll be at rest, with me in it. Ground clearance is 3 inches. I’ll be adding some welded gussets to the extruded ally angle, and some tabs to attach the arms of the watts linkage to, which looks to be ideally situated vertically, at the forward end of the square framework, in the middle. that’s about 1.75inches below the axle centreline. I can set it lower by anything up to another inch and a half by setting it horizontal and mounting it under the frame.

The rubber bands will connect to the square frame, and loop to transverse ally tubes held via U bolts on the underside of the ally.

As many people will point out, rubber bands are great in one direction but rubbish in another. If I were to leave it at this point, I’d have just one more job todo and that would be to paint ‘miss deathtrap’ down the side….
 So I’m not doing that.

As far as I can tell, suspension as a whole is a complex 3D process, with many variables, and dynamically changing loads that ideally need to be balanced out.

 From a guitar makers perspective, it’s almost exactly like designing a tremolo bridge system for a guitar. Lots of dynamically changing loads that need to be balanced out and damped so the system reliably returns to an adjustable zero point, with dynamics and feel to be adjustable by the end user.

Also needs to account for different playing conditions, heavy/light strings, different scale lengths and tunings etc….

Various solutions exist, consisting of all sorts of leaf spring, coil spring in tension, coil spring in compression, and torsion bar designs…

All this needs to be fitted to a lightweight, resonant yet quite astonishingly strong and by turns, rigid and flexible structure….

Omg it’s a racing car isn’t it?
Heheheheeh…

So anyways. Just like on a guitar tremolo, The springing forces need to be balanced in both directions… so they can take heavy deflections in various axes and return to an adjustable loaded zero point with a suitable sort of damping action…so in this case, positive (upwards) deflections of the axle are taken care of by rubber bands… negative (downwards) deflections are taken care of by a couple of conical rubber dampers, situated under the square structure, facing up.

The more towards the centre line these dampers are situated, the livelier the suspension will be.

The more towards the chassis rails, the more rigid it will be.

The cones will be adjustable vertically via way of shims, and horizontally via a selection of mounting holes, from centreline outwards…. At ‘loaded neutral’ ie with me in the car but not going anywhere, the cones will be positively but not excessively loaded. I’m expecting to find a sweet spot with them both closer to the centre line rather than towards the chassis rails.

The cones are available in a huge number of sizes, hardness ratings, spring rates, materials, maximum weight ratings etc. Mine are rated at 116 kg each, and 57 shore hardness, natural rubber and M8 stud mounting. Roughly 50 by 50mm.

This entire idea was inspired by the various works of Alec Issigonis (rubber bands and conical rubber springs anyone?) and also several excellent phone conversations with Rhys, hopefully once I post the pics it should make a bit more sense. Anyways. I reckon it’ll either corner like its on rails or else I’m going straight into the hedge at the end of our lane on first test run….

Jimr1999

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Re: Riley Special chassis (Bridget the Riley)
« Reply #148 on: 31 May 22, 06:10 am »
As Hannibal said... I love it when a plan comes together. I had an early Austin with cone dampers that the front subframe frame was used to provide the front end for a Trio Kit car (which got abandoned after a particularly bad winter wrecked my garage and everything in it) The cones in the kit were tailored with a hacksaw and a knife to lower the stance so it was tunable. I never drove it but it seemed very planted stationary.
Looking very neat sir. The Juno 106 in the background could probably fund an entire CycleKart  ;D
... You can lead a horse to water, but a pencil must be lead.

synthpunk

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Re: Riley Special chassis (Bridget the Riley)
« Reply #149 on: 31 May 22, 10:56 am »
Hmmm… the Jupiter 4 in the rafters could probably fund 2 or three, but then where would the mice live? ;c)