VW T3 syncro conversion

Technical discussion on converting internal combustion to electric
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mursecode
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VW T3 syncro conversion

Post by mursecode »

Hi guys, looking to do something totally different to what i can find elsewhere.
i have a 1992 t3 syncro 4wd. i'm wondering about the suitability of removing the current gearbox/transaxle and replacing it with a secondary front diff and running two AC motors behind each diff to retain 4x4. running only one motor full time and the front one in off-roading situations.

1. would have a final drive ratio of approx 5:1 (38:7) for both motors and would need therefore need considerable torque at low rpms? what should i be looking for?
2. the front motor will not require high speeds whilst off-roading (<50km/hr) so could be smaller than the rear motor that should only need to handle highway speeds or a tad more (>120km/hr).
3. would it be better to have a larger dual shaft motor mid mounted for this application with a de-coupler of some description?

the van is <1500kgs

thoughts? is this feasible?
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brendon_m
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Re: VW T3 syncro conversion

Post by brendon_m »

2x rear motors from an outlander phev? I don't know if anyone has cracked the controller for them but they are minimum 60kw a piece and have the diff and everything there, you'd just need to mount them and modify half shafts.
Or a motor from the back of a lexus hybrid, but they are 700 odd volts so you would have to use the lexus controller or have a relatively high pack voltage. And I don't know what the power output they can do.
mursecode
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Re: VW T3 syncro conversion

Post by mursecode »

Hey thanks that’s actually a good idea, they should have the gearing I’m after with suitable motors. I’ll have to look into feasibility. I was think as I have the two front syncro diffs already it may be easier to match generic motors with the right specs, but I’ll look into the phev as well.

Lexus I’m not sure will have to look into that as well. It’s really in the gearing i foresee issues regarding ratio and how much power I’ll be expecting to burn through whilst off-road and at highway speeds.
T1 Terry
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Re: VW T3 syncro conversion

Post by T1 Terry »

Have you thought about leaving the original gearbox etc intact and just replacing the ICE motor with a suitable electric motor? I seem to remember reading about someone having done something similar, but it might have been an overseas conversion.

T1 Terry
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mursecode
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Re: VW T3 syncro conversion

Post by mursecode »

T1 Terry wrote: Sun, 02 Feb 2020, 10:58 Have you thought about leaving the original gearbox etc intact and just replacing the ICE motor with a suitable electric motor? I seem to remember reading about someone having done something similar, but it might have been an overseas conversion.

T1 Terry
yeah i have, there's a french guy doing/nearly completed his conversion at the moment. ( https://www.youtube.com/watch?v=_E_GTYhXWhY) he's given me a lot of inspiration. however the syncro transaxles are known weak points and very expensive to rebuild etc. i was feeling that as the front diffs would be ratio'd the same, are quite strong and can be locked i would have an ideal 4x4 setup with increased drivetrain reliability.
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Re: VW T3 syncro conversion

Post by T1 Terry »

I guess the other upside is the reduced losses through the various transmissions when only requiring 2WD. Can the front axle be fitted with free wheeling hubs? Can you add a planetary gearset between the motors and diff? That would allow a very low ratio to be selected when 4WD crawling was required and give an increase in torque, but the planetary gearset locked by driving 2 components at the same time for direct drive to give the road speed.

I plan to convert my '74 Kombi to electric drive but keep the gearbox. I want to tow it behind our motorhome and the gearbox won't handle being towed in neutral for long periods. The plan is to tow it with the gearbox in 4th gear so it continually spins the motor while the vehicle is moving. This way the gearbox is splash fed the same way as it would if the engine was driving it and there is no lubrication problems. I'll be using a 3 phase AC motor so there are no brushes to worry about and I doubt the maximum speed would reach 5,000rpm so I'm told the motor will be fine at those speeds.

T1 Terry
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brendon_m
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Re: VW T3 syncro conversion

Post by brendon_m »

Maybe @francisco.shi 's all in one custom motor and gearbox would be the answer
francisco.shi
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Re: VW T3 syncro conversion

Post by francisco.shi »

If you want motors let me know.
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