# 62’ MGA conversion



## Greengear (Mar 27, 2019)

I am ready to embark on my first conversion. I do have significant experience repairing Gem brand electric golf carts. Because I have familiarity with gem car parts and free used parts I hope to use a gem car drive train in my MGA. Thought I would do a sanity check here. 
Some of my assumptions
Gem is 1280 lbs, MGA 1900lbs. We load the fleet gems at work with lots of weight and they still perform therefore gem drivetrain will work for my MGA despite extra weight. 
I plan to drive around the a very busy trafficy urban area so a 25-30 mph speed should be ok. 
The sep ex motor and 72 lead acid pack from the gem are a good choice because they are free!
The MGA has a solid axle the gem has independent fwd. I hope to build axle tubes and mount around the gem motor trans unit so it can be affixed to the mga leaf springs tucking the entire drive under the rear deck ala tesla. Front engine bay would be totally open for large pack. The gem motor comes in variuos power ratings the largest is 7.5hp. Gear box is made by dana. It also has a nicely integrated display and dc-dc converter I would plan to use. 
Any advice / reality check welcome


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## brian_ (Feb 7, 2017)

Greengear said:


> The MGA has a solid axle the gem has independent fwd. I hope to build axle tubes and mount around the gem motor trans unit so it can be affixed to the mga leaf springs tucking the entire drive under the rear deck ala tesla.


If I understand this correctly, you are planning to build a replacement axle which incorporates the motor, reduction gears, and differential. That works, and is a common choice in both golf carts (and similar vehicles) and in heavy trucks; however, high 'unsprung' mass like this is bad for ride and handling, so this solution is not normally considered suitable for a passenger car. It might be acceptable, only because this motor is so small.

Yes, Tesla - and every other manufacturer of modern production EVs - puts the motor (and gearbox, and inverter) at the driven axle(s), but they use independent suspension.


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## Greengear (Mar 27, 2019)

Yes exactly the motor and gearbox would be on the rear axle. unsprung weight does make a clunky ride but this car probably has pretty pathetic suspension in stock form. It has strange elbow shaped devices instead of shock absorbers on all four corners. An independent rear set up would be better nonetheless.


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## brian_ (Feb 7, 2017)

Greengear said:


> It has strange elbow shaped devices instead of shock absorbers on all four corners


Those are shock absorbers (dampers); they're just the old lever type, rather than telescopic.



Greengear said:


> An independent rear set up would be better nonetheless.


Yes, but that's a major change. To what extent do you want it to still be an MGA?


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## brian_ (Feb 7, 2017)

A rear suspension alternative would be to build a de Dion rear axle, with an unmodified motor/gearbox unit and jointed axle shafts. You may be able to use the Gem front hubs.

https://en.wikipedia.org/wiki/De_Dion_tube


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## Emyr (Oct 27, 2016)

*Re: 62’ MGA conversion*



Greengear said:


> I
> The MGA has a solid axle the gem has independent fwd. I hope to build axle tubes and mount around the gem motor trans unit so it can be affixed to the mga leaf springs tucking the entire drive under the rear deck ala tesla.


How about building a subframe to carry the Gem independent suspension and transaxle, bolted into the MGA's leaf spring mounts? It should be pretty easy to replace the steering racks with a separate tie rod for each side.


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## Greengear (Mar 27, 2019)

Another possibility has come up. A friend has an older vw cabrio with the azure dynamics/transit connect 1pv motor and DMOC645 controller that he is willing to sell cheap. The large motor and controller are certainly better quality than gem parts but I wonder if they are too big and poweful for the MGA. Would mating the azure motor to the mga gear box be the way to go if with this option?
The adapter plate and coupler could potentially be modified to work with the mga, all the parts like throttle, charger, wiring could be reused. He is running the motor at lower voltage ( delta?) so around 150v.


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## Greengear (Mar 27, 2019)

brian_ said:


> A rear suspension alternative would be to build a de Dion rear axle, with an unmodified motor/gearbox unit and jointed axle shafts. You may be able to use the Gem front hubs.
> 
> https://en.wikipedia.org/wiki/De_Dion_tube


That looks like it would work pretty well on the mga. Good advice, Thank you


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## brian_ (Feb 7, 2017)

*Re: 62’ MGA conversion*



Emyr said:


> How about building a subframe to carry the Gem independent suspension and transaxle, bolted into the MGA's leaf spring mounts? It should be pretty easy to replace the steering racks with a separate tie rod for each side.


A valid approach, if willing to switch to independent... but does the track dimension match, is the Gem load capacity adequate, and is there space for the Gem suspension? I don't know what the Gem front suspension looks like, but if this parts diagram is it, it is a double A-arm with a high-mounted coilover shock.


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## brian_ (Feb 7, 2017)

*Re: 62’ MGA conversion*



Greengear said:


> Another possibility has come up. A friend has an older vw cabrio with the azure dynamics/transit connect 1pv motor and DMOC645 controller that he is willing to sell cheap. The large motor and controller are certainly better quality than gem parts but I wonder if they are too big and poweful for the MGA. Would mating the azure motor to the mga gear box be the way to go if with this option?


You could do that, but with the motor in the engine space you have the classic EV conversion issue of trying to find space for a large and heavy battery (in some combination of packs). With enough voltage, that motor can probably run the car well without a multi-speed transmission, although you might need a single-ratio reduction box for it... that means that you _might_ be able to put it in the transmission tunnel.


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## Greengear (Mar 27, 2019)

brian_ said:


> You could do that, but with the motor in the engine space you have the classic EV conversion issue of trying to find space for a large and heavy battery (in some combination of packs). With enough voltage, that motor can probably run the car well without a multi-speed transmission, although you might need a single-ratio reduction box for it... that means that you _might_ be able to put it in the transmission tunnel.


The Azure parts do seem too big. I guess a reduction is surely needed since the mga rear end is only a 4.1:1 reduction, probably not low enough for skipping a trans. 
Gem car parts seeming more realistic. Gem track width is 55 inches, MGA is 58. I think adapting the cool MGA wire wheels to gem hubs would be worthwhile but maybe a down the road project after getting it running. The gem sub frame is upper and lower a arm on newer models strut like design on the older models. They both share the same dana box. I have a free early gem drive and electronics at work. I will be looking for a later gem parts group next. I could start conversion with older parts if i end up doing the de dion axle set up.


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## Greengear (Mar 27, 2019)

The gem suspension sub frame seems like it will be too hard to adapt to the MGA because the tops of the shock/ springs are so tall. De dion - solid beam u bolted over top of the leaf springs with motor / gear box hanging below seems simpler. Adapting the hubs or half shafts to include a hollow tube that gets bolted below the leaf seems like the hardest part. See 4-6” long red tubes in pic below. The gem half shafts and hubs dont have anything close to this feature.


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## brian_ (Feb 7, 2017)

*Re: 62’ MGA conversion*



Greengear said:


> The gem sub frame is upper and lower a arm on newer models strut like design on the older models. They both share the same dana box. I have a free early gem drive and electronics at work. I will be looking for a later gem parts group next. I could start conversion with older parts if i end up doing the de dion axle set up.


I saw both designs, but wasn't sure if the older one was really for a Gem... and it's terrible, being basically a swing axle. If you use the older one, it can still work as a parts donor for a de Dion setup, as long as it has outer CV joints (it was hard to tell from the illustration that I saw).


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## brian_ (Feb 7, 2017)

*Re: 62’ MGA conversion*



Greengear said:


> De dion - solid beam u bolted over top of the leaf springs with motor / gear box hanging below seems simpler. Adapting the hubs or half shafts to include a hollow tube that gets bolted below the leaf seems like the hardest part. See 4-6” long red tubes in pic below. The gem half shafts and hubs dont have anything close to this feature.


I think you would need to build replacements (one for each side) for the hub carriers (parts #5 and #6 on the Gem front suspension diagram), to fit the Gem bearings that the Gem hubs (part #8) fit into; however, you may be able to just cut away the no-longer-needed parts of the stock Gem hub carriers. It would be handy if you can modify the Gem pieces, since they also include the mounting tabs for the brake calipers, which need to be strong and reasonably accurate. Those hub carriers get welded onto the ends of the de Dion tube.


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## brian_ (Feb 7, 2017)

*Re: 62’ MGA conversion*



Greengear said:


> The Azure parts do seem too big.


Yes, but that Gem motor is *very* small.


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## Greengear (Mar 27, 2019)

brian_ said:


> I think you would need to build replacements (one for each side) for the hub carriers (parts #5 and #6 on the Gem front suspension diagram), to fit the Gem bearings that the Gem hubs (part #8) fit into; however, you may be able to just cut away the no-longer-needed parts of the stock Gem hub carriers. It would be handy if you can modify the Gem pieces, since they also include the mounting tabs for the brake calipers, which need to be strong and reasonably accurate. Those hub carriers get welded onto the ends of the de Dion tube.


 late gem hub carriers are cast. I dont know if a tube can be welded to them. Early gem hubs get bolted to a flange. Maybe that is the way to go. The early gem brakes and bearings aren't that great. Only good thing about them is I have a pile of every part. 
I wish there was a small cheap reduction box that could go on the end of motor allowing motor and box to fit in place of the original trans. 
As for motor size, the gem motor is certainly under powered. 
Still deep in thought on this project...


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## Duncan (Dec 8, 2008)

Reading this thread I can't help thinking that the Gem stuff is just not suitable - at best you will end up with something a bit feeble

Can you not get hold of a 9 or 11 inch forklift motor to put where the gearbox is just now? - that would make a much nicer conversion for a LOT less work


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## Greengear (Mar 27, 2019)

Duncan said:


> Reading this thread I can't help thinking that the Gem stuff is just not suitable - at best you will end up with something a bit feeble
> 
> Can you not get hold of a 9 or 11 inch forklift motor to put where the gearbox is just now? - that would make a much nicer conversion for a LOT less work


Yeah im starting to think it doesnt make sense too. Im going to look and see what I can find thats in the budget and more worth the effort of installation.


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## Greengear (Mar 27, 2019)

I looked at the azure dynamics drivetrain in person. Definitely seemed too big for the MGA chassis. GEM car parts seem too under powered. 
Next stop is to check out two used huge hub motors. They are probably very cheap as they are used equipment and I gave the original owner owes me a favor. So far all I know is :
96v 150amp controller and motor x 2
Single side axle
4x115mm bolt pattern for mounting wheel to hub. 
I know these are probably very heavy and a bit under powered but my requirements are modest. 30-40 mph need this car for quick trips around the neighborhood.
Going to take a look later this week.
I am imagining something like the image.


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## Greengear (Mar 27, 2019)

The hub motors look good. Two motors two controllers. Controllers look like knock off Sevcons. 
Im just not sure how to mount them. The back of the hub motor seems to have a threaded hollow axle protruding basically a heavy piece of pipe sticking out of the back. 
I want to reuse the mga leaf springs.
Previous owner offered a killer deal $400 for both motors and controllers.


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## Greengear (Mar 27, 2019)

Found an example mounting solution for leaf springs. This looks like a one weekend to mount motors and wiring one weekend to mount pack job. I know these hub motors are weak but I am having trouble resisting. 
See proposed mount solution pick. One reason im not looking for the perfect / best conversion is that I drive an e- golf every day, had a leaf before that. So I really only want to drive this car to the cafe and the beach and I really dont want to spend too much time and money.


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## brian_ (Feb 7, 2017)

*Re: 62’ MGA conversion*



Greengear said:


> The hub motors look good.
> ...
> Im just not sure how to mount them. The back of the hub motor seems to have a threaded hollow axle protruding basically a heavy piece of pipe sticking out of the back.
> I want to reuse the mga leaf springs.


What you would need to build is a dead (no powered shafts) beam axle (tube or bar joining whatever supports the hubs). It's pretty much like building the de Dion setup discussed earlier, but there are no shafts to the middle and nothing there to drive them.



Greengear said:


> Found an example mounting solution for leaf springs.


That works, and is probably what was intended, given that these inexpensive hub motors with their included hub assembly usually have that threaded tube and the wires coming out of the tube.

Just watch the height. The MGA suspension will be designed to have the leaf springs against the top or bottom of an axle tube which is centred on the wheel hubs, and this has the tube offset from the wheel hub. If the tube is offset downward as shown, the hubs will sit much higher in the car (that is, the car will sit much lower). Assuming that in the stock setup the springs run under the axle, then you could have them on top of the new axle tube, which might work out close enough to the right height.

Some beam axles are offset forward or rearward, but with leaf springs that would be a structural issue: the stock springs won't work properly if the tube is ahead of or behind the intended mounting point the axle on the springs.


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## Greengear (Mar 27, 2019)

Well I finally pulled the trigger and bought the large qs hub motors. The included Sabvoton controllers look good too. 
More details to follow after I look over parts carefully tomorrow.


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