# Motor suitability



## GeorgeChapman (Aug 10, 2019)

I have a basic motor suitability question, having found an old forklift motor (which is harder than one might think here in the UK) I need a bit of advice as to whether it is fit for purposes. 

THE MOTOR:
It's a drive motor out of an old Lancing forklift and it's a bit of a monster but doesn't have the continuous output of some others of equivalent size (picture of info plate attached). 
Weight: 110kg
Width: 12"
Length: 15"
kW: 7.5
RPM: 1400
Volts: 67
(144v 100aH battery pack and Paul & Sabrina equivalent open source controller)

THE DONOR CAR:
I am looking at a circa 2005 BMW 1 Series for a couple of reasons a) availability, you can pick them up pretty cheap, ~£500, on eBay b) rear wheel drive, due to the size of the motor I am hoping to omit the transmission hooking the motor directly to the drive shaft c) weight, although not as light as something 20 years it's junior it has a decent curb weight for a RWD hot hatch, ~1,300kg. 

USAGE:
Local driving no more that 20 mile round trips; groceries, school runs and general taxi service for 3 dependants. Max speed limit in the area is 40 mph so that +5/10 mph for overtaking is all I need. Point if note is that I live in the Surrey Hills area and although it's not mountainous it's not flat. 

QUESTIONS:
- Having read somewhere (I can't find the original post) that when it comes to [large] motors it's more about the physical size than the kW output; based on the above is this motor a viable option?

- Is "direct drive" my best option or should I reconsider keeping the transmission? (I still have the original slip yoke from the forklift so hooking up to a drive shaft will be easier than the transmission but nothing is out of the question)

- Can you "direct drive" a front wheel drive car (this would give me more donor car options)?

Many thanks in advance. 
George


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## brian_ (Feb 7, 2017)

GeorgeChapman said:


> - Can you "direct drive" a front wheel drive car (this would give me more donor car options)?
> George


By "direct drive" you appear to mean driving a differential though only one stage of reduction gearing, included in the final drive (the ring gear around the diff and pinion on the input shaft).

You can use a final drive unit (diff assembly or "rear end") from a rear-wheel-drive car, but placed in the front and driving the front wheels. It would be difficult to fit the entire motor ahead of or behind the final drive in most vehicles and using a typical rear final drive. Maybe an Audi or something designed to fit an inline-4 or even inline-5 ahead of the transaxle, with a short-nose final drive? The small rear-drive BMW seems like a more suitable choice, especially if you can jam that motor into the transmission tunnel.


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## Duncan (Dec 8, 2008)

Hi George
That motor sounds eminently suitable! and with 500 amps and 1300 kg will give decent performance - take some pictures of the brushes and comm to show us


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## GeorgeChapman (Aug 10, 2019)

brian_ said:


> By "direct drive" you appear to mean driving a differential though only one stage of reduction gearing, included in the final drive (the ring gear around the diff and pinion on the input shaft).


Thanks brian_ I'm still learning he terminology and this quote alone is worth a good few hours of enjoyable research. I guess all I mean is not using the transmission 



Duncan said:


> Hi George
> take some pictures of the brushes and comm to show us


Great news Duncan, I've attached some photos for your attention. I have also added a couple of pics of other parts of the motor, the rather hefty slip yoke that came attached and the power terminals (there are 3 in total "A", "Y" & "YY")

Thanks again
George


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## Duncan (Dec 8, 2008)

Hi George
Those are decent sized brushes - but it looks like only four of them

The motors we normally use have eight brushes - 500 amps should be OK but probably no more than that

I suspect you will be getting more torque per amp than I do with my Hitachi motor 

It's 67 volts and 1400 rpm

With a 144v controller you may run into the problem that I did when I went to 130v - goes really well but runs out of puff at the higher revs

You may have to jack the voltage up to get highway speeds 

The yoke is great - should be able to tap out the spider and fit it to your propshaft - you will need a propshaft with a sliding joint as well as the UJ's 


https://www.diyelectriccar.com/foru...-dubious-device-44370p9.html?highlight=duncan


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