Reverse gear options USA

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Richard and Pat
Posts: 669
Joined: Wed Sep 26, 2018 2:44 pm
Location: Biggleswade

Reverse gear options USA

Post by Richard and Pat » Tue Jul 26, 2022 5:17 pm

New owner Bob in the USA asks: My car doesn't have reverse gear. Was thinking I might consider an electric reverse like they did on the JZRs, Any guidance there would be appreciated.

steveO
Posts: 56
Joined: Mon Oct 01, 2018 2:08 pm
Location: Calgary

Re: Reverse gear options USA

Post by steveO » Sat Jul 30, 2022 2:30 pm

I thought long and hard over this.
Looked at a guys JZR reverse up here in Calgary, but the JZR has a round tube backbone which allows direct gear to gear clearance for a starter motor meshing with a gear welded via a hub to the drive shaft. With the Triking transmission tunnel there is not the clearance without cutting into the tunnel or using belts or chain drive. This assumes mounting the starter motor at the front. There was/is an owner on here that mounted a starter motor at the rear of the drive shaft, but inside the tunnel. Think he used a Saab motor.
Allen sells a reverse box with replacement drive shafts which is probably the best solution, but for my Mk1 it intrudes too far into the passenger area.
In the end I decided to go without as there are no narrow roads up here and I make sure I park in a pull through spot or facing up a slope so I can roll backwards.
I also did consider making my own reverse box having a machine shop but decided the return on investment and time did not warrant it.
I also looked at trailer movers which require mounting to the swing arm and cutting gear teeth around the rear brake disc, but lack of clearance for a motor.
Steve

Lowpass
Posts: 3
Joined: Tue Jul 26, 2022 11:46 pm
Location: Bend OR USA

Re: Reverse gear options USA

Post by Lowpass » Sat Jul 30, 2022 6:01 pm

Thanks for your insight Steve.
The JZR impemetation I have seen had the starter motor mounted above the rear wheel with a lever actuated friction roller to transmit the motor torque to the rear wheel. A home built caravan mover if you will. A bit crude but I am told effective, as long as the grade is more than the friction coupling can handle. Here are some pictures. I also have a hobby machine shop so would be interested in trying
to fabricate something.
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steveO
Posts: 56
Joined: Mon Oct 01, 2018 2:08 pm
Location: Calgary

Re: Reverse gear options USA

Post by steveO » Sun Jul 31, 2022 2:10 pm

That's interesting as it takes no account of suspension movement being frame mounted, but in hindsight probably is not that big of an issue.
It looks as if just a gear is driving the tire whereas a wider "wheel" would provide more friction.
There is space above the rear wheel on a Triking with minor structural mods.
I did think about a modified 1,000# winch in similar location.
I cant remember its name, but there is a sidecar web site where they play with similar to drive the sidecar wheel.

Lowpass
Posts: 3
Joined: Tue Jul 26, 2022 11:46 pm
Location: Bend OR USA

Re: Reverse gear options USA

Post by Lowpass » Mon Aug 01, 2022 7:59 pm

No direct experience with this arrangement, but it is less intrusive than some of the other designs. It uses a lever to push the friction wheel against the tire (if you zoom in I think you will see a black friction wheel which runs the full width of the tire) with push button/relay to provide voltage to the motor. When not engaged via the lever, the friction wheel is not in contact with the tire. Crude, but no drag on the rest of the system while not in use. Not clear from the pictures whether they just the friction wheel or the whole starter/ geartrain/friction wheel assembly is levered against the tire. Could be done either way I suppose , but just the friction wheel would seem to make more sense and if located at the rear of the tire could provide some cam action to keep things engaged.

There is a youtube video of a guy using a HF winch to provide reverse to an off road go cart. I would call this a fail. https://www.youtube.com/watch?v=RD5OKxa7lJs

Skeomorph
Posts: 28
Joined: Wed Apr 28, 2021 3:25 pm
Location: Reading, Berkshire

Re: Reverse gear options USA

Post by Skeomorph » Mon Aug 01, 2022 9:59 pm

Maybe the Velosolex might provide some inspiration (https://en.wikipedia.org/wiki/V%C3%A9loSoleX)?

These work really well which suggests the amount of friction needed between the tyre and the drive wheel is not a challenge. Never seen one used in the wet though...

Lowpass
Posts: 3
Joined: Tue Jul 26, 2022 11:46 pm
Location: Bend OR USA

Re: Reverse gear options USA

Post by Lowpass » Tue Aug 02, 2022 12:23 am

I may build a friction drive this winter to pass the time. Also thinking of building a longer pointier tail for my type 1 as it looks a little short to me. Much better without the roll bar though.
For anyone interested in pursuing electric reverse, here's a cut and pasted post from a guy that customises motorcycles for handicapped people, Besides providing some interesting insights into various drive systems, sounds like a rewarding and noble endeavor..
"For Harley it is fairly easy to add reverse as it has a remote transmission that is a very simple design. There are also enough bikes out there that the market is large enough for it to make economic sense to develop. A bike like the W800 if a reverse were developed chances are that not enough units would sell to pay for the development let alone the cost of tooling and production. I once worked out how to add reverse to BMW 5 speed oil cooled bikes. Never made a single part as I quickly figured out that at best I would be making work, not money. There is a company that offers a reverse for Harley where it replaces the rear sprocket and is internal to the sprocket. I own the patent rights to a similar design however when I went to put it into production having to our source all of the parts I would have had to sell it for a lot more then the reverse you can already get for the most popular application, Harley. There is a slight chance now that I have CNC mills and a machinist that some day we might produce this in house. Once programmed it would be fairly easy to change tooth count and bolt patterns as needed. If we do this it will be for Indian motorcycles.
We have done electric reverse but only for people who had physical limitations such as wheel chair bound people and amputees' as for able bodied people backing a bike with a sidecar is so easy that it is not worth the expense and effort.
We have done the electric reveres several ways, once we split the spacer for a brake disk on the rear of a Moto Guzzi Convert then put a flex plate flywheel off of a Chevy 2 driven by a starter motor, crude, no real speed control, added a lot of un-sprung weight but did work and as the bike was operated from the sidecar while in the wheel chair was needed and met the budget we had for the build.
We have used a harbor freight winch where we replaced the spool with a hub that contacted the rear tire held in with an electric actuator, This worked however is crude but did fit the need and budget. This was done on an electric shift Suzuki FJR again for some one driving from the sidecar.
On a BMW GS for an amputee we once used a Caravan (trailer) mover where we lowered a wheel down lifting the bike for good traction to back up the bike. It worked well but is bulky and crude and with all of the above we only had one speed, in this case a bit slower then we would want, on the Guzzi faster then ideal.
Harley offered electric reverse for their sidecars. It was expensive, drove the sidecar wheel so if the sidecar wheel did not have good traction it did not work. Took up a lot of space in the trunk and, Harley did not have the battery tied to the bike to charge back up.
Hub motors might be a way to go moving forward however for a company to do this there has to be enough demand to make it worth doing. Finding the right hub motor that moves slow enough and has enough torque to move a bike and sidecars may not be easy. Developing from scratch a hub motor for this and producing it is a money loosing proposition as backing a sidecar bike is so easy if you are able bodied that there will not be much demand unless it is so cheap that adding it makes little difference in the final price of the sidecar.
There is a caravan mover you can buy out of China that the price is low enough that it could be adapted to drive a wheel on the bike if some one wanted to do this as a one off. Makes no economic sense for a company do do this. The issue with Caravan moves is speed. They are very slow."
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