Mazda MX-5e Tesla Powered
Discussion
DHL delivered this today
It’s the fixed gear 1.8:1 reduction box that bolts to the Nissan Leaf motor and reduces the speed down to something that works better with the MX-5 differential, giving a top speed of about 109mph and better acceleration than any MX-5 I’ve ever been in 
It is an expensive part of the MX-5e project but, it’s beautifully made and is an essential part of the design. It is from a company in the USA called Inductive Autoworks.
Edited by robcollingridge on Wednesday 31st January 09:34
Designed the speed sensor ring and I'm currently getting this laser cut from 5mm steel plate. The speedometer sensor uses the teeth to drive thge speedo. and mileometer.
Completed my design for a two channel Tesla water pump speed controller using two ATtiny85 processors and have programmed these. Just getting the PCB manufactured now.
Zunsport are building me a custom stainless-steel grille for the MX-5e in black, without their logo/badge. The current plan is to mount the number plate on this grille, so I don’t need the badge in the way.
We are ditching the chunky rubber mounts that come with the Tesla water pumps. They weigh 142g each. The plan is to use these rubber-lined stainless-steel p-clips instead, which weigh just 32g each. We might use two per pump, to lock the orientation. It all counts, when you want to end up with a lighter EV than the ICE car we started with!
I used a similar approach in my 450kg Fisher Fury R1 and they were 100% reliable, even in the super harsh environment that is a Yamama R1 engine doing clutchless upshifts at 11,000rpm
We managed to modify the MX-5 pedal box to fit the Tesla iBooster bolt pattern by removing the welded spacers and relocating them. This is going to save us a chunk of time and effort. The pedal box is rusty but it will be cleaned up, strengthened in a few places and then powder coated.
All old MX-5’s are rusty, even on the inside. Anyone that claims they have one that isn’t, just hasn’t stripped it down enough yet
We are ditching the chunky rubber mounts that come with the Tesla water pumps. They weigh 142g each. The plan is to use these rubber-lined stainless-steel p-clips instead, which weigh just 32g each. We might use two per pump, to lock the orientation. It all counts, when you want to end up with a lighter EV than the ICE car we started with!
I used a similar approach in my 450kg Fisher Fury R1 and they were 100% reliable, even in the super harsh environment that is a Yamama R1 engine doing clutchless upshifts at 11,000rpm
We managed to modify the MX-5 pedal box to fit the Tesla iBooster bolt pattern by removing the welded spacers and relocating them. This is going to save us a chunk of time and effort. The pedal box is rusty but it will be cleaned up, strengthened in a few places and then powder coated.
All old MX-5’s are rusty, even on the inside. Anyone that claims they have one that isn’t, just hasn’t stripped it down enough yet
Whilst the weather has been poor, we have been sorting out the cabin and interior stuff. We are fitting RGB ambient lighting in the MX-5e using addressable LEDs. The two existing cabin lights have been converted to use the same LEDs. We are adding footwell lighting and light tubes on the door cards too.
The final part of the jigsaw piece that is the brake pedal / pedal box arrived today. The Tesla iBooster clevis was too big and used a 10mm pivot hole. The MX-5 one used a 10mm mounting hole. Fortunately it is easy to buy one the right sized with an 8mm mounting hole and an 8mm pivot hole.
The radiator and fan are in. We used 3mm chipboard to create a template shroud / mounting plate and get everything located nicely. This forces the air through the radiator. It will be made from 1.5mm aluminium sheet once we are happy with everything.
The final part of the jigsaw piece that is the brake pedal / pedal box arrived today. The Tesla iBooster clevis was too big and used a 10mm pivot hole. The MX-5 one used a 10mm mounting hole. Fortunately it is easy to buy one the right sized with an 8mm mounting hole and an 8mm pivot hole.
The radiator and fan are in. We used 3mm chipboard to create a template shroud / mounting plate and get everything located nicely. This forces the air through the radiator. It will be made from 1.5mm aluminium sheet once we are happy with everything.
Finished undersealing the MX-5e. The restoration part of this project is the time consuming bit but, we want to do it right.
We have a new speedo from Speedhut. This is part of bigger project (documented on the OSSEV website) to drag the interior into the future and make it all intuitive and easy to drive.
The LSD diff has been shipped, to upgrade the internals.
We have designed our own custom front lights to go on the MX-5e and the PCB has been sent off to manufacturing. We wanted something along these lines (and this is the colour we are re-painting the EV):
Loads of progress today
Mated the fixed ratio reduction gearbox to the Nissan Leaf motor and removed the inverter, so that we could trial fit it in the transmission tunnel. The inverter will be remotely mounted. It all fits nicely, so we are rebuilding the front end with newly powder coated subframes and suspension parts. All new alignment bolts, ball joints, etc. We are using polybushes on the suspension and have got Meister R coil-overs goong on too.
Now we know that we have to remotely mount the inverter, we have bought this "kit" to do the job properly from Inductive Automotive. It's billet aluminium housings wioth proper seals and should keep all the HV wiring properly waterproof. I wouldn't know where to start trying to build this stuff myself, so I've just bought an 'off the shelf' solution.
The 1.6 diff on the car (6" crown wheel) will be shredded by 350Nm of torque from our Nissan Leaf motor, so we have bought a second hand 1.8 (7" crown wheel) diff (with matching drive shafts). It's a Super Fuji limited slip differential, which should make the car handle better and get the power down
It looks to be in really good condition. This is now being shipped to McNeill Manufacturing Engineering in Northern Ireland, to be upgraded. The aluminium casing is also being strengthened by G19 Engineering.Olibol said:
It’s worth double checking that the Superfuji diff will cope with the torque as well. When I was into supercharging and turbocharging MX5s the Torsen diffs from the 2002 and earlier mk2s were considered the most reliable for big power. There’s a 3.6:1 version that would probably suit the car better than the 3.9:1 Fuji (although I don’t know if making the gearing longer makes as much difference in an EV conversion?
It is a 3.6:1 Super Fuji. It is being upgraded to handle the power/torque by McNeill Engineering.Rob
The front end is back together. We have a freshly powder coated subframe and suspension arms, our new Meister R coil-overs, new polybushes all round, new ball joints and rod ends, new caliper bolts, refurbished and depowered steering rack, new discs and pad, refurbished and repainted calipers and refurbished uprights and brake dust shields. It is basically all new!
It is nice to get the MX-5e outside in the sunshine again and have a bit more room to work on it. We have a few jobs to do before we spin it around and raise it up inside the garage again, to remove the petrol tank and rebuild the rear end. The depowered steering feels super light, though it will weight up a bit with the motor and batteries on board. Whilst we have the car outside, it makes sense to strip the interior again and remove the dash. We are leaving the dash structural bar though as we are now rewiring the whole car from scratch. The reasons for this are to ensure it all works as planned an is reliable, plus we will also save a lot of weight as much of the exisitng loom is redundant.
The test driver said:
Interesting project and a good read so far, I can certainly appreciate the thought, time and effort going into the project.
Although I kinda feel conversions like this are a bit of a functional safety dumpster fire, are you going to have any indication like a HV sticker externally visible on the vehicle to differentiate it from a normal MX5 in case (god forbid) of an accident the emergency services have to respond to?
EVs are safe. I've had a lot more incidents with petrol and hot oil in my vehicles over the last 35+ years. There is just so much less to go wrong in an EV too. I've got a Telsa Powerwall in my garage and I have no concerns with that either. The battery pack will be about 400V and this will kill you if you do something stupid. So will all cars though.Although I kinda feel conversions like this are a bit of a functional safety dumpster fire, are you going to have any indication like a HV sticker externally visible on the vehicle to differentiate it from a normal MX5 in case (god forbid) of an accident the emergency services have to respond to?
The test driver said:
Similar in potential but a very different proposition, the powerwall's been designed, engineered and signed off for static use not dynamic on road, but I'd imagine it will have had to demonstrate certain key safety features like automatic disconnects and HV circuit monitoring too.
Do you have anything in place to monitor the HV wire insulation for shorting or grounding?
My emergency services comment was aimed at a scenario of if the fire services ever had to interact with the vehicle, how would they know where the isolator is? Where could they cut the vehicle body without contacting HV components?
Don't get me wrong and I really don't want to come across as a bit of a knob who dislikes EV's as that isn't me but it's these type of questions that are going to catch out HV conversion'ists very soon.
I'd hate for you to have spent so much time and effort into build something which is quite cool, for the government to catch on and amend sva regs.
I understand your concerns and we will document the whole build. The HV side has isolators for the battery pack and these are standard practice in EV conversions. The battery pack itself has a safety breaker, to ensure it is safe to remove as a complete module. All of the danger and potential danger is in the battery pack really. The HV cables have serious insulation and the cable is mounted on special mounts, to avoid wear. There are a lot of fuses in the system too.Do you have anything in place to monitor the HV wire insulation for shorting or grounding?
My emergency services comment was aimed at a scenario of if the fire services ever had to interact with the vehicle, how would they know where the isolator is? Where could they cut the vehicle body without contacting HV components?
Don't get me wrong and I really don't want to come across as a bit of a knob who dislikes EV's as that isn't me but it's these type of questions that are going to catch out HV conversion'ists very soon.
I'd hate for you to have spent so much time and effort into build something which is quite cool, for the government to catch on and amend sva regs.
Edited by The test driver on Wednesday 20th March 12:52
MesoForm said:
Is there an efficiency gain / loss from spreading the batteries out instead of having them all in once place?
Not really. You spread them out to improve weight distribution and lower the centre of gravity. We are doing an obsessive amount of stuff to reduce the weight of this car and make it lighter as an EV My last car build was 450kg with half a tank of fuel. A Fisher Fury R1 with a Yamaha bike engine and 6-speed sequential gearbox with direct cable paddle shift and a 12,000rpm red-line. https://youtu.be/eNiIzyqP0N0
Stripped out the wiring loom and ECU in the cabin. Most of the existing loom was going to be redundant in an EV and is just going to be a lot easier to rewire the whole car from scratch. We should also save a lot of weight as this lot was around 6kg. Some of the connectors will be reused.
We have now completely stripped all of the wiring out of the MX-5e and started to rewire it with a much lighter, custom loom. We removed lots of redundant wiring that wasn't even used in the original car, much of it for options that were no fitted. I wired my Fisher Fury R1 from scratch so this is not a big job for me and doing it will save us about 8kg off the final weight of the car.
Picked up some "new" mk2.5 leather seats for the MX-5e. These are in really good condition and have the added bonus of being heated. Heated seats make a lot of sense in an open top sports EV, so I am adding genuine Mazda switches and the wiring for these. They can be used to keep you warm, with each seat using just 65W. This is very preferrable to switching on the cabin PTC heater as this can use 3000W. The seats are currently being cleaned and refurbished.
Edited by robcollingridge on Friday 5th April 17:07
Picked up some switches for the heated seats on eBay for not a lot. We are running out of places to put switches, so I’ve designed a 3D printed plate to replace the cubby hole under the radio. This is just a template to check my measurements initially but, they were spot on.
Took the doors off, to get to the last few bits of rust on this car. We are using Buzzweld glass reinforced primer and Buzzweld WAR underseal to protect the car.
We got the LSD aluminium diff casing back from G19 Engineering today. It’s looking really good! We don’t know if this is overkill for our MX-5e but, we have an upgrade path to 215hp and 400Nm of torque, so it makes sense to do it right. We plan to replace the side seals before putting it all back together.
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