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Renard's BMW

Post up a thread for your EV. Progress pics, description and assorted alliteration
Renard
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Post by Renard »

Movement at the station after a month or so of waiting for parts and of general head-scratching.

One job I got done while waiting was to install three rubber mounts under the vacuum pump in order to reduce the vibration which had passed into the vehicle body.

I don't know how others have complied with the requirement to install a low-pressure warning indicator (NCOP 14 #3.2), but for that purpose I bought a differential pressure sensor MPX2100DP from element14 which has a stated output of 0.4mV per kPa. I'll feed the signal through an op-amp and a comparator. The photos show the pressure drop the pump achieves is 90kPa (a reading of 36mV). The switch that came with the pump operates at 26mV or 65kPa below atmospheric pressure.

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Last week I collected the custom-made flywheel from BHSS in Brisbane, and I also picked up the adapter plate. The flywheel is a copy of Coulomb and Weber's, albeit with different dimensions.
Even after multiple careful measurements, the flywheel, when mounted, stood about 1.5mm too proud. How does such a thing happen? But I was able to machine 1mm off the back of the taperlock bush and settle it back towards the output flange. So I'm now within 0.5mm of the magic number of 61.5mm. Thank goodness for a small lathe.

The plate is 10mm steel, and as can be seen in the photo, is secured by four M14 bolts through the motor output flange, tapped into the plate.

Thursday 31st. I assembled the clutch disc and pressure plate. It took a while to machine up a piece of steel to serve as the centring guide for the clutch disc, and it was hard work tightening the screws and bolts with a 6mm Allen key; I had to clamp the key's longer arm to a steel bar, and even then the shorter arm was inclined to twist rather than tighten. I suppose Allen key sockets are available, but I haven't found one.
I'm now ready to install the gearbox into the car. I just have to work out a way to do it single-handed.


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Renard

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Post by Renard »

Friday 1st. Installed the gearbox -- quite a job. I tied the gearbox to a piece of wood sitting on a trolley jack, jacked up the car with my bottle jack, rolled the trolley/gearbox under the car, lowered the car, rolled the trolley into about the right position and lowered the gearbox somewhat and pushed it back for the gearbox forks to engage the rear mounts, installed the crossbrace ready to support the bell housing, slid myself under the car to secure the rear mount nuts, lowered the gearbox onto the crossbrace, fully released the trolley jack, cut the ties holding the gearbox to the trolley jack, rolled the trolley jack away, jacked up the car again to adjust the mounts and fix them properly.
That may sound simple enough, but repeatedly adjusting the gearbox/jack position and sliding under the (lowered) car will, I think, have been one of the physically hardest jobs of the conversion.

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Post by KDRYAN »

Renaed Wrote:

I don't know how others have complied with the requirement to install a low-pressure warning indicator (NCOP 14 #3.2)

I used a Wasco low vacuum switch. The switch closes at 3"HG and opens at 6"HG, factory setting non adjustable. Contacts rated 5amps @ 230vac. 1/8 NPT port, 1/4" spade terminals. Max 30"HG. I have a couple of spares at $10.00 ea plus postage if anyone need one. I have wired it into the brake master cylinder low fluid circuit, so when I have low vacuum I get a warning light on the dash panel. The light is also wired to a warning buzzer.



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Post by 4Springs »

Renard wrote: I assembled the clutch disc and pressure plate. It took a while to machine up a piece of steel to serve as the centring guide for the clutch disc, and it was hard work tightening the screws and bolts with a 6mm Allen key; I had to clamp the key's longer arm to a steel bar, and even then the shorter arm was inclined to twist rather than tighten. I suppose Allen key sockets are available, but I haven't found one.

Not much use me telling you this now, but I found I didn't need a centring guide. Since the motor was out of the vehicle I could stand it on its end to give good access. I could then sit the clutch on the flywheel and centre it by eye, then sit the pressure plate on top and tighten it up.   I imagine that the tool is essential if the clutch has to be assembled in-situ though (with the clutch plate vertical). I ended up buying a set of Allen key sockets, which I could use with my torque wrench.
I note that your old flywheel weighed 10kg, how much does the new one weigh? Don't forget to get the whole thing balanced.

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Post by Renard »



You write:

"I note that your old flywheel weighed 10kg, how much does the new one weigh? Don't forget to get the whole thing balanced."

The new flywheel weighs 7kg, and yes, I had it balanced.
Last edited by Renard on Mon, 04 Jun 2012, 05:14, edited 1 time in total.
Renard

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Post by Renard »

A significant task is to install a ceramic heater in place of the existing heater core. Thank goodness, one can do the job without removing the whole dashboard.
Just in case anyone should want to convert an E36 BMW, this is the procedure.
Following the Bentley manual, which unfortunately doesn't tell you everything you need to know, one removes the gear knob, window and hazard switches, the centre console as detailed here (http://www.bimmerdiy.com/diy/e36armrestrem/), then the front console, the glove box, the passenger airbag, the A/C module, and the steel support that bears the airbag.
I wouldn't say that these tasks were totally trouble-free, but at least that is all one needs to do to reveal the heater box.
Then, give or take a couple of minor fiddles, one can remove the cover from the heater box and manoeuvre it out to the left. After removing the water tubes leading to the heater core using an 8mm nut driver, the core itself comes out with only a little difficulty.
It took several hours to work out just what steps were necessary, including going down one or two false paths and backtracking.
These photos show some stages. The first one shows the LH side with glove box and airbag removed. The control modules are left alone except the top one can be removed, because it's the cruise control. The lightly rusted brown member is the airbag support which is taken out in order to remove the heater box cover.
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The next photo shows the heater box front cover looking like some curious breastplate. The Climate Control module has been removed.

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Here you can see the water piping.

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The heater box cover has been removed here. Note that the airbag support member has been removed in this and the next photo. The pipes have also been removed.

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The ceramic heater can now be mounted in place of the old core, and the HV wiring can be run in a conduit along the route of the previous water piping.
The heater is controlled by using pin18 (yellow/violet wire) and pin13 (yellow/brown wire) of the Climate Control Module. The wires have been brought out to the connector which attaches to the water valves. Pins 18 and 13 go low when the water valves are to open, and high otherwise.
These signals are used to drive a dual optocoupler whose detector circuits control two Mosfets switching the heater on and off. Do I need PWM? I don't know yet. That depends on how the Heller ceramic heater elements -- the same as in Johny's Vogue -- respond to 360V DC.
Renard

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Post by Canberra32 »

Hmmm don't attack me for asking this...
I was looking at your bent pice of angle and while I'm sure the two back to back pices will be ok the ends may not.
will the end pices handle the torque and not deflect or twist?
Remember if your diff angle is let's say 3 degrees then your motor and box angle must oppose the same or the uni joints will unbalance.
They are not like CV joints.
If that mount twists and the angle changes it could unbalance.
I have seen it happen before with angle.

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Post by Renard »

Canberra32 wrote: Hmmm don't attack me for asking this...
I was looking at your bent pice of angle and while I'm sure the two back to back pices will be ok the ends may not.
will the end pices handle the torque and not deflect or twist?
Remember if your diff angle is let's say 3 degrees then your motor and box angle must oppose the same or the uni joints will unbalance.
They are not like CV joints.
If that mount twists and the angle changes it could unbalance.
I have seen it happen before with angle.


The shaft of a 132 frame motor is of course 132mm above the base, and in this case, the mounting points are 108mm from the centreline. Accordingly the force F generated by the motor torque at the mounting points, which is circumferential with respect to the motor, has a horizontal component of 0.774F and a vertical component of 0.633F, these factors being the cosine and sine respectively of the angle between the vertical and the shaft/mount line.
Some proportion, probably a bit less than a half, of these forces is manifested at the rear gearbox mounts.
For a motor torque of 240Nm, the horizontal component of the force is 1088N, or 544N at each motor mounting point. This force puts the RH part of the bracket in tension and the LH part in compression, as the torque tries to move the bracket leftwards. If say 60% of this force is experienced at the motor mounts (and 40% at the gearbox mounts), that is about 653N or 67kgwt force along the bracket.
The vertical forces are 446N at each mount, or 45kgwt, one up, the other down. Again if say 40% of these vertical forces due to torque are transmitted to the rear gearbox mounts, and adding the motor weight of about 66kgwt, the net force down on the RH mount is 27 + 33 = 60kgwt, and on the LH mount, -27 + 33 = 6kgwt.
I'm not a structural engineer, but 50 x 50 x 5 angle seems adequate for these forces.

Regarding the prop shaft angles, the 'official' specified vertical deflections are: transmission to shaft, 0.0° +/- 0.5°; at centre mount, -0.3° +/- 0.5°; at final drive, 1.25°+/- 0.5°. This ideally results in a net deflection of 0.95° between the motor shaft and the final drive. But until the car is fully equipped and loaded I can't check the second and third mentioned angles.
Renard

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Post by Canberra32 »

Yeah that will do it :)
Had two of my friends not listen to me about Phasing the uni joints when they raised the hell out of their 4wds.
Told them it's not a cv it changes angular velocity it will vibrate if they don't roll the diffs because the new suspension droop angle messed with the alignment.

Apparently the wiki article they read made them experts and the resulting vibration they had was too much power or maybe a curse from a gypsy lol.
That angle the car company put into their cars could be covered by a sticker to fix it maybe lol.

After 30min and two spanners later I fixed it... Then they just claimed it must have been loose to start with lol.
And all this from two guys who spent hours complaining about why do we need engineers lol
This is why I don't help them on their cars anymore :)


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Post by weber »

Canberra32 wrote: Yeah that will do it :)
Had two of my friends not listen to me about Phasing the uni joints...


That's a good point Canberra32. With our 132 frame induction motor in our MX-5 we were forced to have the shaft at the front of the motor about 40 mm higher than the ICE shaft was. So the gearstick is about 20 mm higher. But fortunately our diff is connecetd to our gearbox by an aluminium truss beam, so it automatically pitched on its rubber mounts by the necessary 1 degree and kept the uni joints in alignment.
One of the fathers of MeXy the electric MX-5, along with Coulomb and Newton (Jeff Owen).

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Post by Canberra32 »

Yeah I bought and modded my ex-wife a NB mx5 they are a tidy little car.
There are two tips for them though.
A brace bar or roll bar between sides just behind the seat at the top.
Weld up a cross bracing frame to bolt on and close the tunnel.
I diddnt believe the guys at the mx5club that it made such a difference.
I was soooooooo wrong! It totally changes the feel of the car.

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Post by Renard »

I recently picked up a new flex disc for the drive shaft -- thinking that it would save trouble to renew it while the shaft is out. So last week I installed the drive shaft and that has enabled me to get a fix on the longitudinal position of the motor, which can now be installed.
This task was a bit fiddly; I had to wire up the motor to the lifting chain to get it to assume an appropriate angle to mate with the bell housing, and getting it into place required rolling the car forward under the motor, lowering it, and rotating the motor slightly whilst nudging it backwards. But eventually the locating dowels lined up and the motor pulled in with the nuts on the fixing bolts.
One photo shows that the terminal box comes close to the steering shaft. To give good clearance I replaced the existing cast cover with an aluminium plate with acrylic sheet glued to the inside. I wired up the terminals beforehand, as it will be tricky to get to them with the motor in position.
The mountings are a two-piece kind to absorb forces both up and down. I had to buy a 19mm drill bit to make the two holes which accommodate them. Getting the mounting bolts in was touch and go, as the RH bolt was only just short enough to fit under the terminal box. I had a nasty moment there when I realised I hadn't checked beforehand to see if it would fit. The M10 bolt had to be long enough to take the base plate plus rubber mount plus snubbing washer and nut.
The last photo shows the extent of the free real estate. Like all estate photos, it's not quite as much as it looks.

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Post by Johny »

Great progress. Those terminal boxes are a pain - the industrial community like them BIG. I like the 10c piece for size perspective.

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Post by Huub35 »

Hi Renard,

just out of curiosity, what distance to/over the steering system do you have with the 132 frame motor. I have a 160 frame size, and was always under the impression it would not fit over the steering system and crossmembers, but looking at your pictures, it seems there is plenty of room left.

Regards,


Huub

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Post by Renard »

Huub35 wrote: Hi Renard,

just out of curiosity, what distance to/over the steering system do you have with the 132 frame motor. I have a 160 frame size, and was always under the impression it would not fit over the steering system and crossmembers, but looking at your pictures, it seems there is plenty of room left.

Regards,


Huub


If the motor footplate (which doesn't reach quite as far forward as the crosspiece) were extended forward, it would just clear the steering unit by a few mm -- perhaps 5mm. The motor body, which of course is higher than the footplate, clears the steering unit by about 30mm. The motor is mounted perhaps 5mm higher than it should be, meaning that there is a vertical deflection of 0.3° at the gearbox/transmission universal joint. This is within specifications.
For a 160 frame motor, you'd need to mount the motor 28mm (160 - 132) higher, or at least 25mm, (in which case the aforementioned deflection would be about 1.5°) or cut the footplate short -- or something!
It would depend on the exact motor shape and your ingenuity.

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Post by BigMouse »

Renard wrote: If the motor footplate (which doesn't reach quite as far forward as the crosspiece) were extended forward, it would just clear the steering unit by a few mm -- perhaps 5mm. The motor body, which of course is higher than the footplate, clears the steering unit by about 30mm.


I'm curious, did you consider mounting the motor with the footplate on a side or on top? My motor has removable/relocatable feet on it and I'm considering building a frame that mounts directly to the foot mounting points on the case (with the foot removed). The frame would have to be more complicated, but the motor could be mounted lower. I haven't removed the ICE from my E36 yet (still my daily driver), so I'm not sure how the measurements work out.

Also playing with the idea of suspending the motor from a frame mounted between the strut towers. This would act as a frame stiffener, provide a handy mounting point for the controller, and allow plenty of clearance for the motor and steering rack. The frame would have to be pretty big and heavy though.

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Post by Renard »

BigMouse wrote:
I'm curious, did you consider mounting the motor with the footplate on a side or on top? My motor has removable/relocatable feet on it and I'm considering building a frame that mounts directly to the foot mounting points on the case (with the foot removed). The frame would have to be more complicated, but the motor could be mounted lower.


No, it had not occurred to me. In my case it wasn't necessary to depart from standard practice. But it's true that removing the foot saves you maybe 15mm (about 20mm less your custom bracket thickness.)
I don't like the sound of your second idea. It seems safer to me to employ the existing engine mounts; we know they are suitable. And my arrangement gives me all that volume over the motor to play with.
Renard

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Post by Renard »

With the motor installed, I thought to check the weight of the car to see how I'm going. It now weighs 510kg at the front, and 570kg at the rear, for 1080kg total so far -- 300kg less than the original weight. That helps to plan the distribution of cells.
My current intention is to put 16 cells in the forward lower box (one row of seven, and one of nine), 20 cells in the forward upper box (two rows of ten), and 23 cells in the box over the motor (two rows of eight and one of seven). There will still be enough space over this last box to site the controller and some other electrical components.
Under this plan, there will be 15 cells under the rear seat, and 38 in the boot. That's 59 front, 53 rear, or 112 total.

The ceramic heater core has now been installed in the heater box, and some parts such as the airbag support and airbag replaced.

I have made up two brackets out of 1.6mm gal sheet to carry the Bosch accelerator pedal, which was bought from Johny, surplus to his needs. Two studs of the brake pedal support serve to hold the upper bracket, and two 5mm rivnuts were inserted into the lower firewall to carry the lower bracket. I'm happy to get rid of the old lever and cable system; it seemed rather antiquated.

Pins 2, 3, 4 of the unit are used to produce a resistance derived voltage from a 5V supply; the output ranges from 0.72V to 4.72V. I didn't have the specific plug to fit the pedal, but I found that a Molex Minifit plug would serve. The Minifit has a 4.2mm pitch which was close enough to the 4.0mm pitch of the pedal pins.

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Meanwhile, I have been fabricating two brackets which fasten to the front chassis rails out of 50 x 50 x 4 gal steel. The brackets support the lower front battery box, the upper front box which is directly above it, and the front of the box over the motor. The rear supports for this latter box will be oddly shaped one-offs tailored to fit in the awkward positions that the box requires.
Each bracket is secured to the chassis rails by five M10 bolts and rivnuts.
The two photos following show the RH bracket, and the LH bracket in position but as yet unbolted.

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The elevated portion of the bracket is to seat the front lower member of the box that sits over the motor.
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Post by BigMouse »

Great stuff! The weights, the fitment of the accelerator pedal (that's the Polo one, right?), all very valuable information for helping me plan my own E36 conversion. I'm surprised at the weight loss. The ICE, exhaust, fuel tank, etc made up nearly 400kg!? (assuming nearly 100kg for your motor and mounting). That's much more than the 100kg estimate for motor weight I found online.

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Post by Renard »

BigMouse wrote: Great stuff! The weights, the fitment of the accelerator pedal (that's the Polo one, right?), all very valuable information for helping me plan my own E36 conversion. I'm surprised at the weight loss. The ICE, exhaust, fuel tank, etc made up nearly 400kg!? (assuming nearly 100kg for your motor and mounting). That's much more than the 100kg estimate for motor weight I found online.

Thanks BigMouse. It's really helpful to know that one's work record can be useful to others. I'm very grateful to other contributors for all that I've learned.
About weight: my motor weighs only 69kg, the ICE motor was about 185kg, and there was 50kg of fuel in the tank when I recorded the original 1380kg weight. Where did the rest go? I've lost track, but the PbA battery and spare tyre make up 40kg.
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Post by Renard »

Slow progress lately as I have been felling dozens of camphor laurels nearby -- they are are a noxious weed round here. Slow work too, to fabricate the two brackets for the rear mounts of the box which sits over the motor. Made from 50x50x4 gal angle, these are awkwardly shaped, and each is secured with one M10 and two M8 bolts. The corresponding rivnuts were also awkward to install. The photos show their location, and a piece of angle loosely placed to indicate the battery box edge. I couldn't find anywhere else to put these two rear mounts.


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On another matter, I was just about to disassemble the steering column covers to remove the cruise control switching mechanism when the thought occurred to me that since it constitutes four switches, it could be used for other functions. Each switch action sends a pulse to the cruise control module. I was thinking that perhaps it could replace a regen. slider control or maybe cycle through some display.
Any ideas?
Renard

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Post by celectric »

Renard wrote:On another matter, I was just about to disassemble the steering column covers to remove the cruise control switching mechanism when the thought occurred to me that since it constitutes four switches, it could be used for other functions. Each switch action sends a pulse to the cruise control module. I was thinking that perhaps it could replace a regen. slider control or maybe cycle through some display.
Any ideas?
Hi Renard,
I planned to do something similar in my conversion. My donor car has an LCD panel with fuel and temperature gauges and odometer, which I planned to replace with a general-purpose LCD that I can use to display a variety of EV-specific details. I was looking for some way to mount a set of buttons on the steering wheel to control that display when I realised, like you, that I could repurpose the cruise control lever as an input mechanism, to switch between different display screens and cycle through options. One of its features would still be cruise control, which I believe is quite easy to achieve with the Tritium controller. When cruise control is switched off, I also planned to use it to set a speed limiter - many cars will beep at you if you're going too fast but with the WaveSculptor it's easy to just rev-limit the car to the speed limit, if you know the gearing ratio.

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Post by Renard »

Excitement yesterday when my batteries finally arrived. 112 cells in six boxes packed 21 to a box. Every single one, without exception, measured 3.30V. This cold morning at 14.5°, I put a 0.5Ω resistor across a cell and it dropped to 3.07V, but recovered of course in a couple of seconds.
Weight is 3.17kg each. One reason I selected the 100Ahr cells is because they have an Ahr/kg weight ratio of 31.5, the best of all the CALB range with the exception of the 180Ahr cell at 32.1.
Now to get on with the boxes.

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Post by Johny »

Wow that's a lot of cells! Great stuff!
If all those cells go into the BMW your pack will be 3 times the capacity of mine.

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Post by Renard »

Johny wrote: Wow that's a lot of cells!


Well, I'm going for range. Country driving. The pack is nominally 360kg, and 36kWhr.
Renard

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