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reality404 posted:

I bought my Sinclair C5 May 2014 after wanting one for years. I got it working and on the first test drive round where I live I had trouble getting up a small hill. I decided it would make a fun project to convert it to 24 volts and that it would also help with the hills.

I sadly suffer from chronic headaches and hypopituitarism so the amount of time my health has allowed to me work on converting my Sinclair c5 to 24 volts has been very limiting.

So far I have:
Replaced the gearbox insert with a metal one from “SINCLAIR C5 CHAS”.
Replaced the control box a with 4QD Porter 10 (can use 2 12v batteries in series for 24v or 1 12v for 12v).
Replaced the motor switch with a Magura twist grip from 4QD.
Taken apart and put the Sinclair C5 back together to clean it.

I have only run the Sinclair C5 at 12v with these modifications due to not having a way to cool the motor yet. The last time I tried to ride the Sinclair C5 I noticed the belt was slipping. I tried everything I could think of to fix the belt slip but could not. I decided to take the gearbox off and have a look I noticed the outer casing was cracked. I posted on the forum asking if anyone had one for sale and someone pointed out the armature had snapped off the motor.

At this point I need:
New motor.
Way to cool the motor.
Rear indicator’s.
Way to control lights/indicators.
Way to monitor battery/speed.
Better brakes.

I really love my Sinclair C5 and enjoy riding it and working on it when I can. I really want to get my Sinclair C5 working again but I’m unsure how to continue any advise would be welcome. I will continue to update this thread with the progress I make with my conversion.

posted on: 21/05/2015 11:25:05

Karl posted:

Hi reality,

taking your points one by one.

1) New motor.
2) Way to cool the motor.
3) Rear indicator’s.
4) Way to control lights/indicators.
5) Way to monitor battery/speed.
6) Better brakes.

1) Might be able to help, but it would be better to obtain one from the UK.

2) You can fit a cooling fan using one of Dan's fan mounts, but you'll need a 24v fan unless you tap off 12v between the batteries. 12v fans are ten a penny in ebay.

3) You can order rear indicators from Ray1 (he's a member), again it's a 12/24v question, LEDs or filament bulbs. You will also need a flasher unit relating to the voltage you select.

4) Chas has an indicator switch unit for sale.

5) A standard voltmeter unit can be fitted. For speed a bicycle computer, ensure that it works with 16" wheels before you buy..

6) Chas has front and back disk brake units for sale, so contact him for these and the indicator switch.

To contact Chas or Ray1, look in the mebers list. For Chas look for 'Sinclair C5 Chas', just send them a PM or email.

Av phun.

posted on: 21/05/2015 15:31:57

reality404 posted:

Thanks Karl for the pointers.

I sent CHAS a message just after I posted the thread about breaks and a motor. I will also look up the indicator switch.

As for a fan I have plenty of 12v fans lying around from working with computers just need a bracket I will get in touch with dan.

I need to look at getting a voltmeter for the battery's. Right now for speed I have a old bike GPS until but it's very hard to read will look into bike computers.

I will get in touch with Ray1 about the replicated rear indicators.

Thanks again.
posted on: 21/05/2015 16:23:59

Dan posted:

Hi Reality, Regarding the belt slipping, have you checked out this mod. I've had the belt slip on me plenty of times until I did this mod using a cable tie:
posted on: 21/05/2015 18:16:16


Hi regarding the fan a computer fan is not powerful you need a more powerful one for cooling on 24volt
posted on: 21/05/2015 18:47:26

reality404 posted:

Thanks Dan I tried that cable tie trick and a couple of others but It did not help with the belt slip. I think the belt ship was coursed by the armature breaking off.

Thanks Chas for the warning I will look for a heavy duty 12cm fan.
posted on: 21/05/2015 19:50:11

Karl posted:

Hi reality,

just a couple of other points.

Seeing as you have no motor at the moment, I suggest that when you obtain the new motor you improve the cooling air flow through by moding the case. The original exhaust vents leave a lot to be desired. I tried the find Chas's post covering this mod, but to no avail, so I've added a couple of his photos. If you mod the case take care that when you drill you don't make contact with the magnets. With this mod a 12v computer fan should work well, but a 120 fan is still better.

If possible, you should fit the original motor thermal cutout switch to prevent damage to the motor.

Last but not least. There is no point in wasting power cooling a cold motor, so fit a thermal switch, in line with the fan voltage supply, to the body of the motor. The switch should close at about 30 to 35°C, this way the fan only switches on when the motor is warm. They are quite cheap (see link), so it's worth fitting. The item in the link is just a sample, there are others that are cheaper.

Hope that this is of some help to you.


posted on: 22/05/2015 12:37:36