Weber and Coulomb's MX-5

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Post by juk » Thu, 12 Mar 2009, 19:40

The tie rod end IS a ball joint.

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Post by fuzzy-hair-man » Thu, 12 Mar 2009, 19:54

juk wrote: The tie rod end IS a ball joint.
Yep, have done both steering arm/rods and the ball joints at the top of the suspension with the whack it on the side of the taper method and this was recommended to me by my father who is also a mechanic after I got half way to stuffing it by whacking it on top Image luckily the thread wasn't stuffed enough that it effected things.

And the ball joint splitter will also do both, because I have done both with them. Image and it's much easier and less likely to stuff things, I've also seen a bearing puller used to pull apart the steering rod ball joint.

Sorry if I'm using the wrong terminology I always forget the right one...

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Post by coulomb » Fri, 13 Mar 2009, 07:25

How do you weigh a car, and the various pieces that come out of it? Ross Pink suggested this idea: various planks of wood and a set (about 8) of bathroom scales. We adapted his idea a little by only measuring one axle at a time and adding the result. We considered just one wheel at a time, but that would compress the spring on the wheel being measured more than usual, and add more force that the scales would interpret as extra weight.

Here is the setup we used:
Image

A closeup:
Image
Those are six identical bathroom scales purchased at the local hypermarket for $11 each. We considered pooling our various existing scales, but they were slightly different heights, so they would not share the load evenly. As it was, the unevenness of the concrete floor meant that some scales registered twice that of the others, but it doesn't matter; the sum of the weights should be correct.

Edit: The tyres rest on some square section steel fence posts I had lying about, cut to the length of three scales side by side. They are held together with some steel strap, so they don't come apart and let the weight of the wheel come down on the middle scale by itself.

Edit: We compensated for the weight of the posts (about 3kg) by simply adjusting the zero to actually read zero after the posts were placed on the scales. The actual readings with only the posts changed a bit, but it all cancelled out as the readings still added to zero.

We ended up with 466kg on the rear, and 517kg on the front, for a total of 983kg. It happens that the 1993 MX-5, which has the same 1.6L engine and power steering as standard, has a published kerb weight of 983kg. Amazing. For the record, this is with a stock 1990 MX-5 but with power steering, air conditioning, full petrol tank, spare tyre (taking it out registered 8.5kg less on the rear), front tie hooks removed, rear tie hooks present.
Last edited by coulomb on Thu, 12 Mar 2009, 20:38, edited 1 time in total.

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Post by coulomb » Sun, 22 Mar 2009, 04:23

One of the next most important decisions is what number and kind of LiFePO4 battery can we fit. To answer this question properly, we need to get the fuel tank out, so we can visualise the spaces available and plan the various battery boxes. As you can imagine, removing the fuel tank is a moderately messy and dangerous job.
Image

That's a 5kg CO2 fire extinguisher. It was required for insurance of some expensive IT equipment years ago.

In the MX-5, the fuel tank is behind the seats, under where the soft top rests when down, forward of the boot. In order to get the fuel tank out, the entire sub-frame holding the differential has to be dropped down. First, the Power Plant Frame has to come out.
Image
The hole circled is where the speedo pickup goes through the PPF. Our manual neglected to tell us to remove the speedo cable before removing the PPF.

The PPF connects the gearbox to the differential, and stiffens the whole power train against twisting. The only thing holding up the rear of the gearbox is the PPF via the differential.

According to the manual, the gearbox has to be drained as well, or the gearbox oil would leak out when the tail (propulsion) shaft was removed. I think we could have left out this step, as we didn't remove the tail shaft from the gearbox, but rested it on a cardboard box out of the way of the PPF.

A lot of the power train is coated in oil and grime. To get things clean and shiny (and they are more likely to stay that way in an EV) in an environmentally friendly way, we use this citrus based product, "Citro CLean":
Image
It smells a hell of a lot better than oil-based degreasers, and works quite well. This bottle was some $5 from Coles.

Edits: why we are doing this now; more on what the PPF does.
Last edited by coulomb on Sat, 21 Mar 2009, 17:41, edited 1 time in total.

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Post by coulomb » Mon, 23 Mar 2009, 07:39

Finally, the tank is out:
Image
At the top you can see some of the pipes that came out (and ran 3/4 of the length of the vehicle), and also the "jiggle siphon" that we used to drain most of the fuel from the tank before starting. I tried to buy an ordinary squeeze siphon, and couldn't find one. Big W had these, and they work well enough. Jiggling the hose in conjunction with the ball valve weakly pumps fuel to get the siphon started (no sucking required Image).

We decided to lower the rear sub-frame (carrying the differential), rather than taking it out altogether. That meant we had to manoeuvre the tank between the top of the tank retaining metalwork and the top of the subframe. It was a huge effort to get it through this small gap.

The biggest mistake we made was to worry about the subframe sagging down too far, or falling on us. So we built stacks of bricks and wooden planks to rest the bottom of the subframe on. However, this proved unnecessary and also prevented the subframe from going low enough to get the tank out. We had to rotate it so much to get it out that it ended up upside down.

The resultant space looks like it will provide good battery space for us and make our planned conversion possible. Zeva found that he could not get his larger batteries in there, but with our much larger motor controller, we'll need to use most of that space (near where the fuel tank came from) for batteries.
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Post by weber » Mon, 23 Mar 2009, 20:02

The MX-5 fuel tank is the most ridiculous and asymmetrical and complicated shape you ever saw. I've seen toads that look nicer. That photo doesn't show the half of it. It's as if they blew up a balloon in the only space that was left, then had that shape made out of steel. At the back there's an indentation in it for the spare tyre (that you can see in the photo), then it gets really thin as it oozes down between the body and subframe, and then it kind of wraps over both sides of the propshaft and the PPF (the alloy torque-beam that conects diff to gearbox). We'll definitely need to use this fuel-tank space for batteries.

We were then able to measure the space and find, as we hoped, that we can put one layer of 40 Ah TS cells (allowing for 210 mm high) over the area above the rear subframe but below the rear parcel shelf (soft-top folding shelf). And in the smaller region in front of the subframe but behind the wall behind the seats (on either side of the propshaft and torque-beam). We can put them two layers deep there. And we can put another lot (just one layer) behind the rear-subframe underneath the boot, as zeva did. But because of our lower-height cells we shouldn't have to eat into the already tiny boot-space as zeva did, except for the spare tyre indent. I think we'll just replace the spare tyre with a can of emergency inflater-sealer. Is that legal?

We still need to fit a lot of cells under the bonnet. The Control Techniques 75/90 kW drive is 800 mm x 300 mm x 300 mm. We plan to run the long dimension front to back under the bonnet, on top of the long 132 frame motor. Then we need to fit cells (maybe two deep), down both sides of the motor and drive.

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Post by fuzzy-hair-man » Mon, 23 Mar 2009, 20:23

weber wrote: I think we'll just replace the spare tyre with a can of emergency inflater-sealer. Is that legal?
I've heard that it is not a registration requirement to have a spare but if you do have a spare it must have legal tread. This may have been NSW, not sure about Qld.

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Post by EV2Go » Tue, 24 Mar 2009, 23:09

“According to the manual, the gearbox has to be drained as well, or the gearbox oil would leak out when the tail (propulsion) shaft was removed. I think we could have left out this step, as we didn't remove the tail shaft from the gearbox, but rested it on a cardboard box out of the way of the PPF.”

Very smart move, another little trick if you are taking the gearbox our regularly or storing one for a while, is to get an old cactus tail shaft and take the yoke off it. In days gone by some manufacturers used the same spline for multiple gearboxes, I had an old yoke for a Holden that fit all the three and Aust built 4 speed boxes. Came in handy a number of times including changing a gearbox on the side of a road.
fuzzy-hair-man wrote:
weber wrote: I think we'll just replace the spare tyre with a can of emergency inflater-sealer. Is that legal?
I've heard that it is not a registration requirement to have a spare but if you do have a spare it must have legal tread. This may have been NSW, not sure about Qld.
A very long time ago I got pulled over by some overzealous boys in blue, and because we met on a bend and by the time they had done an illegal U turn and got behind me they couldn’t prove I was “allegedly” speeding, so after trying the old “you could be man enough to admit you were speeding” spiel (like I would be dumb enough to admit it even if I was speeding) so they went over my car with a fine tooth comb to send me for a machinery inspection.

Because it was a Holden ute I was carrying the spare in the back, and because it wasn’t quite as happy as it could be, they used that as one of the 3 things that qualified a trip to main roads. The inspector at main road said they were just cowboys and he couldn’t give a rats what the spare was like or even if I had one as long as it wasn’t on the vehicle.

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Post by coulomb » Wed, 25 Mar 2009, 05:11

weber wrote: The MX-5 fuel tank is the most ridiculous and asymmetrical and complicated shape you ever saw. I've seen toads that look nicer.

This image may convey a little more of the toady ugliness:
Image
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Post by Electrocycle » Wed, 25 Mar 2009, 05:27

wow!
worst fuel tank ever!
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Post by weber » Wed, 25 Mar 2009, 16:26

Electrocycle wrote: wow!
worst fuel tank ever!

Yeah. But I have to say, the vehicle that was wrapped around it so tightly is the most gorgeous thing ever. And soooo much fun to drive. Next best thing to a motorcycle for throwing around corners on winding mountain roads, with the top down. I'm having withdrawal symptoms.

But gentlemen, we can rebuild her. We have the technology. We have the capability to build the world's first AC MX-5. Better than she was before. Better, stronger, faster.

And she won't cost six million dollars.

Forget the Tesla, here comes the Coulomb and Weber Roadster.

Sorry. I got a bit carried away there. Image
Last edited by weber on Wed, 25 Mar 2009, 07:34, edited 1 time in total.
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Post by Johny » Wed, 25 Mar 2009, 16:36

That's OK - it was a suitable use of the monologue from the show - I could almost hear the creaking noise his arm made...

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Post by EV2Go » Wed, 25 Mar 2009, 16:45

Looking at that tank photo, I think some of that 6 million dollars will need to be spend on air bladder support before that leaps anything Image

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Post by coulomb » Fri, 27 Mar 2009, 06:35

Today we made a final guesstimate of how many TS 40AH cells we can fit in the back; we came up with 148 (with some problems to solve). We may not even end up cutting the boot floor; one layer of 65 cells should fit under the boot where mainly the muffler was.

So we've made the no return decision: we're go for conversion. Image Image

This afternoon we prepped the engine for removal. The plan is to get everything ready for an old fashioned Engine Lifting ceremony at Nerd's Night next Wednesday. The bonnet is removed, the power steering pump and air conditioner compressor are tied out of the way, a dozen hoses and wires were removed, even the engine mounting bolt nuts are removed. Oh, and radiator and two fans.

Next: reinstall the tail shaft and Power Plant Frame (so the gearbox isn't held up just by the bricks as at present), and undo the engine to gearbox bolts.
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Post by Electrocycle » Sat, 28 Mar 2009, 05:47

often it's easiest to remove the engine and gearbox together, but I haven't done it on an MX5 :)
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Post by Richo » Sat, 28 Mar 2009, 08:18

coulomb wrote: How do you weigh a car, and the various pieces that come out of it? Ross Pink suggested this idea: various planks of wood and a set (about 8) of bathroom scales. We adapted his idea a little by only measuring one axle at a time and adding the result. We considered just one wheel at a time, but that would compress the spring on the wheel being measured more than usual, and add more force that the scales would interpret as extra weight.
Those are six identical bathroom scales purchased at the local hypermarket for $11 each.


Thanks for the tip. Image
I made up a jig for measuring one wheel at a time.
The other wheels were "chocked-up" to the same offset height.
I had to pay nearly $13 each for my scales from the Big W Image
Image

EDIT: Not enough emoticons Image
Last edited by Richo on Fri, 27 Mar 2009, 21:19, edited 1 time in total.
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Post by coulomb » Sat, 28 Mar 2009, 17:06

Oooh, fan-ceeeee!   Image    Welded, painted, shiny bolts, very nice.

We condidered just doing one wheel, but decided it would be inaccurate because of the different compression of springs. I hope your "chocking up" works well to counter that.
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Post by Johny » Sat, 28 Mar 2009, 20:48

If he's chocking to the same height then the different spring compression should still result in an accurate weight once all wheels have been measured. A shame this kind of work is being repeated (and I have yet to do something similar). I was going to try a single set of scales and a lever - that's how I weighed my engine. Not as accurate but provided it is repeatable then it will serve the purpose.

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Post by coulomb » Sun, 29 Mar 2009, 07:01

The MX-5 is ready for Nerd's Night:
Image

The idea is that many eyes and hands can watch for and correct hoses and cables that are about to be caught etc. Plus, it's a nice, hands on nerdy thing pulling out an engine (and gearbox this time; we decided it will be easier to separate the engine and gearbox out on the garage floor).

There is still one last hard to get to bolt that has to come out before the last hydraulic pipe (clutch) is free.
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Post by coulomb » Sun, 29 Mar 2009, 21:02

The fuel tank, as pictured earlier (only one tiny hose, caps for hoses and fuel level sender) weighs a surprisingly low 9kg. I suspect it's made of aluminium alloy. The bolts are carefully insulated with rubber gadgets to prevent dissimilar metals connecting electrically.

Edit: as pictured earlier.
Last edited by coulomb on Sun, 29 Mar 2009, 10:03, edited 1 time in total.
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Post by coulomb » Thu, 02 Apr 2009, 06:49

Image The engine is out! Image
ImageImage
Weber decided that it was easier to take the gearbox with it, and separate the two on the garage floor.

The engine bay is moderately clear; there are plenty of cables and pipes to clean up.
Image

When attempting to lift the engine at first, we found that we were just lifting the front of the car. One engine mount was coming loose, but the other seemed stuck. We tried various raisings and lowerings of the engine and gearbox, to no avail.

Finally, I decided it might be stuck against the firewall, so we reconfigured the chain to pull only on the engine lift hook nearest the firewall. Almost immediately there was a great crack and a jolt; I'd say the engine mount had 19 years of sticktion that needed force from a different angle. We reconfigured the chains on both bolts, and it came out. It was a very tight fit, partly because we couldn't readily adjust the angle of the engine with the chain in tension. In fact, the top of the gearbox pulled a bit on part of the firewall at the top of the transmission tunnel, distorting it slightly. No biggie. We were much more concerned about damaging the air conditioner radiator.

Pulling the engine and gearbox really was easier with four people. Two handling the engine lifter, two making sure that things weren't getting stuck or damaged.

The engine and gearbox combined weighed in at 170 kg, including alternator but no steering pump or air conditioning compressor.

Edit: extra picture
Last edited by coulomb on Thu, 02 Apr 2009, 14:41, edited 1 time in total.
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Post by coulomb » Fri, 03 Apr 2009, 01:28

The gearbox is separated from the engine now.

Here are pictures of the bell housing before and after degreasing:
ImageImage

The gearbox on its own weighs 45 kg. The seats weigh 9 kg each.

We've started the next step, which is cutting some metalwork behind the seats and in the boot. That should allow us to settle on exact battery box sizes.
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Post by acmotor » Fri, 03 Apr 2009, 03:04

The digital scales on the boom lift say 500kg Image

(just above the safety footware !)

Question. Do you have a mechanical engineering signatory lined up ?
What is their comment re cutting of bodywork in a monocoque vehicle ?
What suggestions do they have re structural integrity ?

This would be good info for followers of this thread.
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Post by Mesuge » Fri, 03 Apr 2009, 03:53

This topic would be perhaps more appropriate in the dedicated technical thread, but are you still after the following spec. for your desired VFD (EValbum): "Control Techniques, Likely 75/90 kW SK5402" ?

I've found some dealer's pricing on them, and it looks quite *attractive < £2,500 for a new drive in the area of 30-45kW nominal rating (RedSuzi&Mal comparison)

http://www.inverterdrive.com/group/AC-I ... px?Page=10

Usually, used Danfoss drives are not that much cheaper..

--
* I know the DC guys must think we are crazy to pay more just for VFD
with half the power they pay for a complete conversion kit (w. out batts)
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Post by weber » Fri, 03 Apr 2009, 04:38

That's our friend Eddie with the camera and the bare feet. You'll note he was well back. Image Although he had crawled under the vehicle earlier, to free the gearbox from something it was catching on. It really helped to have 4 competent people there when removing the engine and gearbox.

We were very concerned ourselves about what we could and couldn't cut on the MX-5, so we talked to the best person imaginable, in the whole of Australia, for advice on this topic. He just happens to be here in Brisbane.

*****************************
* Richard Larsen, BEMech, MIEAust *
*****************************

He not only wrote the first edition of NCOP 14, as you can see here: NCOP 14 Preface
but he also happens to be an expert on MX-5s (and a really friendly bloke).

On weekdays he runs Loadsafe Australia and on Saturdays he runs MX5Plus.

So last Saturday we traded a bunch of MX5 parts that we won't be needing any more, for an hour and a half of his time. We prepared a list of questions in advance. And, being at MX5Plus, we had a stripped shell of an MX-5 in front of us to walk around and point at.

Even though it is monocoque, there are fairly well defined chassis rails and cross members. They are recognisable as box beams despite being made of folded and spot-welded sheet steel of the same thickness as the outer skin. But sometimes it's not obvious. Sometimes you have to measure things inside and outside the vehicle to be sure it's a single skin you're looking at and not a boxed in section.

Basically, we could cut any single layer of steel sheet between those rails and cross members, on the assumption that the battery racks, trays or boxes put into those spaces will restore the lost stiffness. They will typically more than do so.

Richard wasn't able to be our engineering signatory, but recommended another engineer, David Blythe, who we will be contacting soon.

[Edit: Changed "did crawl under the vehicle later" to "had crawled under the vehicle earlier" and fixed up NCOP 14 Preface URL]
Last edited by weber on Fri, 03 Apr 2009, 06:04, edited 1 time in total.
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