Scaffolding poles + old VW bits + Rotary engine....

Scaffolding poles + old VW bits + Rotary engine....

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Discussion

lufbramatt

5,318 posts

133 months

Monday 2nd February 2015
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chuntington101 said:
How do they do it in the Audi R8 / Lambo Gallardo?
Looks like they offset the prop shaft slightly to the right to clear the sump then it kinks back to meet the front diff on the centreline.

PhillipM

Original Poster:

6,515 posts

188 months

Monday 2nd February 2015
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^^Yup, the takeoff is offset to one side of the differential in the transaxle, so you end up going down the side with the prop and a joint in the middle, not terrible, but the issue then is that the differential area is wider by the full width of the joint to the prop - which is stealing length from the driveshafts and limiting the length of your suspension legs. Doesn't matter for something with 5-6 inches of travel, does if you want 16 hehe

chuntington101

5,733 posts

235 months

Monday 2nd February 2015
quotequote all
PhillipM said:
^^Yup, the takeoff is offset to one side of the differential in the transaxle, so you end up going down the side with the prop and a joint in the middle, not terrible, but the issue then is that the differential area is wider by the full width of the joint to the prop - which is stealing length from the driveshafts and limiting the length of your suspension legs. Doesn't matter for something with 5-6 inches of travel, does if you want 16 hehe
I see the issue now! smile Hmmm maybe Max's hydraulic drive on the rear of the box isn't such a bad idea after all! forget all the variable speed stuff, just do a 1:1 ratio as you just want to transfer the power. Could something like this take the torque?


anonymous-user

53 months

Monday 2nd February 2015
quotequote all
PhillipM said:
^^Yup, the takeoff is offset to one side of the differential in the transaxle, so you end up going down the side with the prop and a joint in the middle, not terrible, but the issue then is that the differential area is wider by the full width of the joint to the prop - which is stealing length from the driveshafts and limiting the length of your suspension legs. Doesn't matter for something with 5-6 inches of travel, does if you want 16 hehe
The point about suspension travel and drive shaft / wishbone length is CRITICAL for this application!

One idea i had was to run a de-dion rear beam (light / stiff, constant ground clearance) with chain drives running down long trailing arms, meaning you could use a std fwd engine/gearbox transversely.

(Like a combination of Andy Burtons Peugeot Cosworth and Clive Hudsons Eclipse:




Sandwich a suitable hydraulic pump in between engine and gearbox, or use a hang-on spur box (a-la Haldex) to drive it. A few flow control valves and a nice big motor at the front, and you could get enough front drive to get through the rough stuff and out of corners well, without a massive weight / package penalty.


anonymous-user

53 months

Monday 2nd February 2015
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PS perhaps we should start a "novel 4wd" thread in the "Engines/drivetrain" section to avoid distracting PhilipM..... ;-)

PhillipM

Original Poster:

6,515 posts

188 months

Monday 2nd February 2015
quotequote all
Haha, no worries, I don't mind.

We did think about chain drive with this one with the longer rear arms but really didn't have the time to sort it - the idea being to run the driveshafts to just behind the pivot points and then run a chain down the arm - can have as much rear travel as you like really then, but keeping the chain system sealed and lubricated adds a little weight to the arms, plus the additional bearings, etc - and we wanted a cush drive system on the hub if we did it - as you know from the old safari chain drive attempts, it takes a lot of TLC to keep them going with open chains and shock loadings.

chuntington101

5,733 posts

235 months

Tuesday 3rd February 2015
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Surely this tech is off the shelf though? There are thousands of off road bikes out there that are all using chains in similar conditions to what you will be running in.

No they aren't delivering the power or have the weight that your setup will have which could make the above statement a load of b0ll0cks. smile

PhillipM

Original Poster:

6,515 posts

188 months

Tuesday 3rd February 2015
quotequote all
Yep, that's the issue really, 5-10 times the weight, 3-4 times the power, a lot taller and wider tyres and the associated massive increase in shock loading (Just our rear wheels and tyres alone probably weigh at least half of what most dirt bikes weigh in total), makes for a big, heavy, wide chain* unless you run a massive sprocket to reduce the leverage - and then you end up with wear and heat issues because of the surface speeds combined with all the grit and dirt. So then you want to enclose it, keep it clean, and have a lubricant bath for it to run through, so you end up wanting an enclosure down the arm with seals and bearings either end and an oil bath and seperators.
Some have tried them open with large multi-link chains but they take some TLC and the industrial chains they've tried really aren't designed for running that kind of speed around relatively small diameter sprockets, so they tend to stretch and jump without keeping on top of the maintainance and adjusting and cleaning through an event, much like you'd do with a bike but it's a bit more hassle with a car sat in the mud biggrin



  • (well, imagine the bottom of the above increases, that would mean running a minimum of about 15 typical dirt bike chains and sprockets to each wheel if you were using them...obviously it's not that bad as the chain strength/stiffness increases much more than the weight as you go up in size for a single chain, but it gives an idea)
Edited by PhillipM on Tuesday 3rd February 12:23

firemunki

361 posts

130 months

Tuesday 3rd February 2015
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Now I'll admit I know the square root of b*gger all about this but the talk of chain drive a'la moto cross bike requiring a monster chain, couldn't you use a motorbike style shaft drive?

PhillipM

Original Poster:

6,515 posts

188 months

Tuesday 3rd February 2015
quotequote all
firemunki said:
Now I'll admit I know the square root of b*gger all about this but the talk of chain drive a'la moto cross bike requiring a monster chain, couldn't you use a motorbike style shaft drive?
You could indeed, turning the drive through 90 degrees twice presents a few issues itself mind, but it is something we considered at the time. As usual having a budget of £2.49 and half eaten mars bar stopped proceedings.

anonymous-user

53 months

Wednesday 4th February 2015
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The other issue with long "driven" radius arms is the massive squat you're going to get on any surface with any level of traction.

It would be interesting to "run the numbers" for a hydraulic hang-on FAD (Front Axle Drive) and see what you could make with relatively in-expensive parts (loads of commercial hydraulic motors/pumps etc) the control valves would be the most expensive parts, and even then if you wanted to forgo super fast response you could probably bodge something that would work!

chuntington101

5,733 posts

235 months

Wednesday 4th February 2015
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Max_Torque said:
The other issue with long "driven" radius arms is the massive squat you're going to get on any surface with any level of traction.

It would be interesting to "run the numbers" for a hydraulic hang-on FAD (Front Axle Drive) and see what you could make with relatively in-expensive parts (loads of commercial hydraulic motors/pumps etc) the control valves would be the most expensive parts, and even then if you wanted to forgo super fast response you could probably bodge something that would work!
Max, could you not just use the Pump / motor to drive a t a 1:1 ratio? Could uses a 4WD gearbox then with a pump mounted on the back.

Watchman

6,391 posts

244 months

Wednesday 4th February 2015
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This has some serious long travel sus:

https://www.youtube.com/watch?v=13rELGs_ZLE

Doesn't it just have "normal" driveshafts?

PhillipM

Original Poster:

6,515 posts

188 months

Wednesday 4th February 2015
quotequote all
Sort of, but look at the length of them, and the arms. And the width of it, it's wider than ours that has two seats in biggrin
The longer the shafts are, the less angle they're doing for a given travel, and it's the CV angles that limit you (well, and your tyre height in compression, we could have 20 inches of travel at the rear with some taller tyres, but it'd destroy the gearbox). To be honest, we're not near the limits of the CV's any more at the rear, we run out of plunge before then anyway, but we've intentionally strapped the car short of what it can do for the moment.

Plus those narrow wishbones wouldn't be attached to the chassis for very long over Safari terrain wink



Edited by PhillipM on Wednesday 4th February 13:26

PhillipM

Original Poster:

6,515 posts

188 months

Sunday 8th February 2015
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I'm afraid there's be a terrible accident in the workshop.

















The flywheel fell into the lathe and we couldn't reach it in time, it was viscously attacked by a passing boring bore, and when we eventually got it out, has lost a considerable amount of flesh. He's resting on the bench now under a sheet, but I fear he may never be the same again...
)
Of course, if anyone wants to donate bacon sandwiches to see if we can bulk him back up, feel free...;)

rhinochopig

17,932 posts

197 months

Sunday 8th February 2015
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I'm beginning to think it would have been easier to start with a solid lump of billet and machine a buggy out of that.

PhillipM

Original Poster:

6,515 posts

188 months

Sunday 8th February 2015
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rhinochopig said:
I'm beginning to think it would have been easier to start with a solid lump of billet and machine a buggy out of that.
It would have been faster. Even if it was hewn by hand with flint chisels.

PhillipM

Original Poster:

6,515 posts

188 months

Thursday 26th March 2015
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Haven't been very active here due to family health issues and struggling with an infection myself for a few weeks, in fact, I'm at home today as I made myself ill again working too long last night, hey ho.
That aside, I'll get some pictures tommorow, honest - but the new floorpan is fitted up, Ed's made a new front bonnet and bulkhead, pipework/bulkhead fittings have gone in, new seat mounts are there, there's some more things to press and light up on the dashboard, ECU has been mounted, new brake/clutch reservoirs have been adapted and fitted, altered the wiper system so it autoparks and there's 2 speeds (sound trivial, but if you're giving someone a ride and they park the wipers right in your line of sight it's quite a distraction!).
Airbox prefilters are sorted and are going in tommorow to keep the larger items - grass/leaves/wasps*, etc, out of the cooling system and save the engine filters having to deal with 'em, got some more to do on the chassis loom as there's some spare wiring/connectors going in for future upgrades and because we're probably switching to a different PAS pump sometime in the year, so connectors for that are going in just in case.
Still plenty left to do on the hydraulics side but it's mainly just straight runs of pipe to the bulkhead connectors for the brakes, and a new fuel line.

Modified the lathe last week so we can spin 16" wheel rims in there - just - so we can make some new wheels much easier than before by skimming them true after welding them up.

Not far away (yes, I know, we've said that for 2 years - you're more than welcome to come and help if that's a problem hehe )


  • Yes, wasps - the roof scoop draws from the high pressure area at the windscreen. Anything that hits the windscreen tends to go upwards. Including swarms of wasps, on more than one occasion. You try cleaning an airfilter full of injured and/or REALLY pissed off wasps)

Watchman

6,391 posts

244 months

Thursday 26th March 2015
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PhillipM said:
Yes, wasps - the roof scoop draws from the high pressure area at the windscreen. Anything that hits the windscreen tends to go upwards. Including swarms of wasps, on more than one occasion. You try cleaning an airfilter full of injured and/or REALLY pissed off wasps)
Funny - maybe an additional fuel injector to sizzle them on their way in? hehe


Looking forward to pics. Love this car.

PhillipM

Original Poster:

6,515 posts

188 months

Thursday 26th March 2015
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Oh, it's actually on all 4 wheels now too!