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XL-erate 11-26-2012 08:35 PM

2WD design thoughts [First post update: RESTORED]
EDIT: I wrote this out once and then had some unpleasantness following so I deleted most of it. Seems it needs to be written up again to correct some errors and try to explain better and more fully. At the same time let me add that if folks couldn’t understand it the first time that it dawned on me that maybe it was written for crap and wasn’t clearly understandable! I didn’t want to take up miles of bandwidth the first time but maybe it was abbreviated too much.
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So because I posted it up in the first place I’m going to assume all blame for any difficulty understanding it and apologize for losing my temper over some of the replies. Claude Stanley mentioned that he personally knew a couple of posters who replied, that they’re good people and he doubted they meant to be directly offensive, or if so they were just having a bad day. Good enough for me. Without further ado:
I’m working on building an outfit in the near future and have given a lot of thought to 2WD. I hear a bunch of negatives and complications, but most all say the traction is great if it works so it sounds good to me. Possibly this planned design would be of use to others contemplating 2WD. This has been tested with some very high loads and extremes of applied horsepower but not in a sidecar rig.
It is my own original design not based on any other Limited Slip drive system or differential I’m aware of. I’ve worked and searched around the automotive, truck, bike, kart, race etc. scene for 50 years while looking for a Limited Slip like this and never heard of it yet so I went ahead and designed it myself. It isn’t stolen from another application or anyone else’s design that I’ve ever heard of but it is based on a simple clutch and driven plate, underlining simple.
I have a complete bike rear wheel/sprocket/brake for my hack with bike's original swingarm and shocks. This build will have a PTO at engine. Come off the PTO with a u-joint [maybe not necessary] to a driveshaft with splined connection and spring loaded clutch assembly and across under the chair with a driveshaft. Chain drive from driveshaft to sidecar rear wheel.
For the PTO come off the engine’s countershaft output sprocket to another sprocket on a jackshaft, with jackshaft of course mounted in bearings. 1<SUP>st</SUP> jackshaft sprocket spins shaft and powers the PTO power takeoff at other end. Add another sprocket next to the first on jackshaft, this aligned with a sprocket on a lay shaft mounted in bearings behind it, in front of rear wheel. Add another sprocket to lay shaft, this aligned with bike’s rear wheel sprocket and original countershaft sprocket and normal drive system is restored plus you now have the jackshaft PTO.
PTO & layshaft mountings may be simple plates, possibly in a boxed configuration and aluminum should suffice, or plates may be suspended between a few new, small diameter tubes added to frame with shafts in quality roller or thrust bearings as needed.
In order to make system usable in full-time 2WD: a driveshaft is mounted to PTO, possibly by u-joint, with driveshaft split in two. Choice of keyed or splines for mounting u-joint if used on jackshaft. U-joint may not be needed depending on configuration. Mount drive shafts in bearing supports under chair with flanged thrust bearings and thrust collars/washers as needed.
Jackshaft PTO end on chair side should be in a thrust bearing with mounting acting as thrust plate with suitable thrust washer/collar as needed, to withstand force applied by driveshaft. Proper high quality thrust bearings, thrust collars/washers are critical here where non-thrust bearings would be shredded in short order and could possibly lock up bike or chair wheel!
On the two adjoining ends of cut driveshafts attach hubs/plates facing each other. One plate gets clutch-type friction material and the other may be a steel plate, or friction material on both. There are shops that rebuild clutches so it shouldn’t be hard or expensive to get a custom hub/plate faced with friction material, or else do it yourself. One steel plate is better so that only one friction material needs replacing in the future.<o:p></o:p>

These hub/plates press against each other face to face, carrying power from jackshaft PTO across under chair through driveshafts to a sprocket on far end to drive chair wheel. Driveshaft should be mounted in thust bearings with thrust collar on shaft as needed. Mount it all up so that it's adjustable for spring pressure between the 2 shaft ends with hub/plates and friction material if desired.<o:p></o:p>

One driveshaft end may be splined with that shaft’s clutch hub/plate internally splined and then spring-loaded. A coil spring over outside of shaft from a shaft mounted thrust collar to clutch hub applies constant spring pressure to clutch plate against adjoining steel plate on the other shaft as needed, but with options on spring ratings. A thrust collar is required on shaft for spring to press against to maintain pressure on splined hub/plate and multiple springs might be used. A second spring over outside of first might be engaged with an adjustable thrust collar when 100% lockup is required, disengaged for normal riding.<o:p></o:p>

Clutch hubs and plates may be mounted in the open space between tug and chair for the sake of ground clearance. Note: mounting for driveshafts with clutch assembly may be made adjustable for a quick increase or decrease of spring pressure. Also it may be possible to eliminate u-joint and second driveshaft and simply run a steel hub/plate directly on jackshaft end and friction hub/plate on single driven shaft end carrying power to sidecar wheel sprocket, obviously the simplest setup.<o:p></o:p>

The only outside-sourced machining operation required is to have shafts and hub splined, however there are sources for custom splined shafts. Nothing huge needed, just enough to handle your bike engine’s horsepower. Not that difficult to make your own hubs and plates and some will have leftover machine parts that will do nicely for all needed parts with a little modification. <o:p></o:p>

Some were dubious that a single small clutch/driven plate of 5”-6” diameter could withstand pressures and power applied in this way. Same system is used successfully with 800-900, even 1,000+ HP applied to a single 12”-13” clutch plate/driven plate in countless drag racing applications. In street machines countless more vehicles running 200-700 HP with single 10”-12” clutch and driven plates for about 50,000 miles before even changing clutch frictions in normal use. Even the extreme torque of large diesel-powered trucks is handled by a single 12”-13” clutch plate for many thousands of trouble free miles. It works, use whatever clutch/driven plate size you think necessary.<o:p></o:p>

With this setup I can adjust by spring pressure and bearing mounts to have full traction or less, like about 50% of full engine power on hack wheel, give or take. This allows light enough pre-load so that sidecar axle and wheel can slip as needed in turns on hard surfaces, either speeding up or slowing down, but as if free-wheeling. <o:p></o:p>

Of course I'd expect some clutch plate wear over time, maybe not all that much. It would be quite similar to the continuous slip seen 4-5-6 times at every stop light or stop sign in an automotive manual transmission system but here with less applied horsepower, far less mass or weight to move and much less slip than that overall. This slip allows the 2WD to function as a Limited Slip differential where the driveshaft sections are similar to the axles in an L/S setup.<o:p></o:p>

This setup would give a whole lot more extra power on soft surfaces and leave everything drivable on hard surfaces with axle/wheel speed differentiation as needed. For my own use it will not see extreme offroad but still planning to lightly enclose clutching assembly so a bunch of trash and guck doesn’t foul it. Something like a light gauge aluminum box to keep things fairly dry and clean.<o:p></o:p>

I hope that explains things better and that some folks can get some good use out of this. There's a further possibility written in between the lines but I'll leave it to you all to discover it. I still can’t get it written to be perfectly understandable to all but hopefully this is better. I have no lasting grudge or animosity against anyone here and afterall, it is the Christ-mas season, eh? Have fun!



Biebs 11-27-2012 05:54 AM

Good idea, Look at these 2WD builds
This is simple and woks:

This is using - mobec unit very interesting:

scroll all the way to the bottom to see build


Here is the money shot hope Murph is ok with me posting his picture:

Your idea of using a PTO from the engine is different from these 2 keep us updated with pics - the 2 links provided have great pictures and you have to admire the thought and engineering that goes with them. Also a clutch arrangement instead of a locking hub will be different.


XL-erate 11-27-2012 11:06 PM

Thanks for the info, pics and links, Biebs!

My point in posting was to show guys how to do a super cheap limited-slip drive system that anybody with good mechanical skills can build. Good for a hack rig but also applicable to any other 3-4 wheeled vehicle. Also total horsepower doesn't much matter as long as there's room for large enough clutch plates. Full time 2WD can get pretty weird and at the worst times too.

I've received a whole bunch of tech info and much more for free from the internet so this is part of paying it back. Hope guys get some good use out of it.


SamM 11-27-2012 11:17 PM

Lately, I have also thought a great deal about building my own 2WD sidecar rig. I currently own both a KTM 950 Adventure and KLR650 that I was installing a Versys engine into. My thought is to install the Versys engine sideways into the KTM frame and run a driveshaft back to a Subaru rear differential. If I turned the engine more towards the left, I could actually run a driveshaft offset just a bit. With the differential turned the axles could be offset just enough to have the sidecar wheel ahead of the rear wheel on the bike. It's interesting to think about but I haven't worked anything out. I'll probably just sell everything and buy a Ural GU.

SamM 11-27-2012 11:20 PM

Could a BMW rig be used on American highways with a sidecar on the leftside, like this?

SamM 11-27-2012 11:44 PM

Yet another idea, would be a Diesel/Electric drive. Use a Diesel engine to run a generator that powers an electric motor coupled to a Subraru differential. With the motor and the differential offset, you could power both the motorcycle and sidecar wheels. Add some batteries and you could have a Diesel/Electric/Hybrid 2WD motorcycle sidecar. I would make a complete frame with the suspension mounted like a car and set the KTM frame onto it. The KTM drive and electrics could even be used. With the KTM frame bolted down onto the sidecar frame and the batteries under the tub, think of the stability.

vortexau 11-28-2012 01:35 AM

With 2WD its not so compelling to have a lead on the hack wheel. The WWII Norton Big4 military outfits had tug-rear and hack wheel in line.

Its a lot to do with where the combination C.O.G. sits.

Consider this- its quite feasible to employ a complete transaxle+gearbox from a rear-wheel drive automobile. Since solo BMWs have had VW aircooled boxer fours coupled up to their existing transmissions ---- the reverse must also be possible: coupling a late-model BMW oilhead motor onto a beetle (or kombi) transmission!

Use this for simple 2WD, and modify to produce un-equal drive power-split like 65% Tug & 35% Hack.
Even a complete buggy rear frame could be attached to a motorcycle front end!
Boxer twins are a very versatile design! They've even appeared as Two-Strokes.

vortexau 11-28-2012 01:52 AM


Originally Posted by SamM (Post 20132317)
Could a BMW rig be used on American highways with a sidecar on the leftside, like this?

Why not stick with a tug that one could run Right Hand PTO to a RH hack?


A BMW rear hub good for Left or Right PTO duty!

Biebs 11-28-2012 09:02 AM

Trike or sidecar??
When you start talking a rear wheel arrangement where both rear wheel and sidecar wheel are on the same plane you are talking TRIKE.

Sidecar design has the sidecar wheel leading the tug rear wheel.

Has anyone ever looked at a sidecar with a lagging sidecar wheel?? Sound like it would be dangerous.:eek1

But let try to stick to Sidecars on this Board!!!!:freaky NO TRIKES!!!!!

Biebs 11-28-2012 09:04 AM

Trike or sidecar??
TRIKE - rear wheels in common plane

Sidecar - Sidecar wheel leads rear wheel:freaky

XL-erate 11-28-2012 09:48 AM

This thread is about a true DIY Build at Home 2WD System for hack outfits and other vehicles. This thread was intended to show an original design for DIY 2WD on sidecar rigs.

I reviewed all the other options. None of those other ideas even come close, not within miles of providing what this design offers.

1] COST: Lowest by far, a couple of $100 not $1,000's!

2] Simplest of all known designs.

3] Ultra-Lightweight configuration, could easily be under 25 lbs total.

4] True DIY: Ease of building all components yourself at home.

5] Only 1 machining operation required: splines.

6] Extreme strength suitable for any horsepower and torque range.

7] Useable on any sidecar-trike or vehicle with 2 wheels that can be driven.

8] Works on any motorcycle ever built if a simple jackshaft PTO is added.

9] No limitations on Track Width - 18" to 18', doesn't matter, custom fit.

10] Simplest to adjust or repair on the road, most others not repairable on road at all.

11] Simplest to completely disconnect on the road, most others can't be disco'd on road.

12] Extreme Reliability through basic simplicity, fool-proof design with very few parts.

13] Absolute minimum wearing or possibly failing parts.

14] Absolute minimum moving parts.

15] Easily and quickly adjustable for ANY desired traction advantage up to locked rear.

16] No high-priced MANUFACTURER ONLY parts.

17] No parts destined to become obsolete.

18] Parts pricing structure not controlled by Manufacturer or Sales network.

19] No 'Proprietary' Manufactured parts.

20] No complicated and expensive parts, gears, doo-dads etc.

21] Every single part easily carried onboard as a spare.

22] Traction advantage may be changed in minutes or seconds.

Biebs 11-28-2012 12:30 PM

THANKS for what????
Without pictures of a working model it is an idea in your head show the working model!!!!:eek1

ag_streak 11-28-2012 01:23 PM

I too would like to see at least a sketch of what you're proposing! :freaky

And now for something completely different...

I was thinking in a different direction. "Temporary" electric 2WD.

What if you simply had a deep cycle marine battery mounted on the hack frame and powering an electric motor with chain drive through an electric clutch to a sprocket mounted on the hack wheel, and a push button for your thumb on the handlebar?

Not intended for continuous operation. Just to get you unstuck out of mud or deep sand. You'd still be using your rear tire to provide thrust, but the sidecar wheel would be helping instead of hindering. The electric clutch could engage at the same time the power is applied to the motor, to prevent the motor shaft from turning all the time. It would negate, or at least minimize, the need for a winch for getting unstuck.

Best of both worlds, no? :ear

Or am I once again orating from my anus? :lol3

vortexau 11-28-2012 04:44 PM


Originally Posted by Biebs (Post 20134389)
When you start talking a rear wheel arrangement where both rear wheel and sidecar wheel are on the same plane you are talking TRIKE.

Please quote YOUR reference for that assertion!

Norton Big 4
Looks more like a combination than a trike, to me!

Rear end (1924x544 pixels)
Still looks very little like a trike, to me!

Sidecar design has the sidecar wheel leading the tug rear wheel.

Lets revise that blanket statement, shall we?
"Sidecar design usually has the sidecar wheel leading the tug rear wheel, but there have been exceptions!"

But let try to stick to Sidecars on this Board!!!!:freaky NO TRIKES!!!!!
Trikes and Cyclecar discussion are permitted on this Forum section. Don't be a bigot!

vortexau 11-28-2012 04:50 PM


Originally Posted by Biebs (Post 20134406)
TRIKE - rear wheels in common plane

Sidecar - Sidecar wheel leads rear wheel:freaky

Still wrong!

Trikes are considered as symmetrical three-wheelers.

Sidecars can be termed as unsymmetrical three-wheelers

Not ALL sidecars employ wheel lead.

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