Solid Mounting A Motor

Open for any sort of non-technical discussion regarding EVs
User avatar
EV2Go
Senior Member
Posts: 2059
Joined: Wed, 16 Jul 2008, 00:21
Real Name: Paul
Location: Brisbane 1963

Solid Mounting A Motor

Post by EV2Go » Thu, 29 Jan 2009, 01:59

Just looking for a bit of actual hand on experience advice here...

Hypothetically, if there was no way to mount a motor (let’s say a TransWarp 11) other than solid mounting it, how much vibration would be transmitted to the chassis? Are we talking could easily put up with it, or would it drive you nuts in 5 minutes and no way it could be done?
Last edited by EV2Go on Wed, 28 Jan 2009, 15:01, edited 1 time in total.

User avatar
Electrocycle
Senior Member
Posts: 985
Joined: Sun, 19 Oct 2008, 20:23
Real Name: Andrew
Location: Sydney
MSN: dumhed@dumhed.com
Contact:

Solid Mounting A Motor

Post by Electrocycle » Thu, 29 Jan 2009, 02:10

that is pretty hypothetical :P

Most of the transmitted noise would come from the drive train it's connected to I think.
If you solid mounted it you could easily use the motor as a stressed chassis member :)

On my bike, the original engine makes a fair bit of vibration, and the electric motor makes none at all, both solid mounted.
Last edited by Electrocycle on Wed, 28 Jan 2009, 15:11, edited 1 time in total.
The Engine Whisperer - fixer of things

User avatar
EV2Go
Senior Member
Posts: 2059
Joined: Wed, 16 Jul 2008, 00:21
Real Name: Paul
Location: Brisbane 1963

Solid Mounting A Motor

Post by EV2Go » Thu, 29 Jan 2009, 02:30

ok that was what I was kind of hoping for.

This is the front chassis

http://www.minimania.com/web/Item/21A25 ... I%20COOPER

and

http://www.minimania.com/web/Item/HMP24 ... k%20brakes

if the electric motor was mounted north - south instead of the usual east - west there may be little to no room to put in rubber mounting but instead it would become a structual member like you say.

User avatar
acmotor
Senior Member
Posts: 3595
Joined: Thu, 26 Apr 2007, 03:30
Real Name: Tuarn
Location: Perth,Australia

Solid Mounting A Motor

Post by acmotor » Thu, 29 Jan 2009, 03:07

Do check with whoever is going to be your mechanical signatory for inspection. It may be OK but they need to be happy with it to sign off.

ADRs ask for vibration isolation (although questionable with emotor) and I was advised that the emotor could not be used as a structural member unless by design of motor manufacturer.
(although I have seen all sorts of things approved)
iMiEV MY12     105,131km in pure Electric and loving it !

User avatar
Electrocycle
Senior Member
Posts: 985
Joined: Sun, 19 Oct 2008, 20:23
Real Name: Andrew
Location: Sydney
MSN: dumhed@dumhed.com
Contact:

Solid Mounting A Motor

Post by Electrocycle » Thu, 29 Jan 2009, 03:21

actually that's a good point.
I think for cars the engine actually has to be on rubber mounts.
The Engine Whisperer - fixer of things

User avatar
EV2Go
Senior Member
Posts: 2059
Joined: Wed, 16 Jul 2008, 00:21
Real Name: Paul
Location: Brisbane 1963

Solid Mounting A Motor

Post by EV2Go » Thu, 29 Jan 2009, 03:35

Actually come to think of it it wouldn't be that hard to rubber mount it even with length limitation. I could always put those big straps around the motor both ends, bolt some engine mounts up to the straps and just have some flat plate (facing backwards off the front chassis section and facing forward on the rear chassis section)and bolt it up that way.

If 4 engine mounts are enough to make them happy nothing will.
Last edited by EV2Go on Wed, 28 Jan 2009, 16:36, edited 1 time in total.

Rob M
Groupie
Posts: 88
Joined: Thu, 17 May 2007, 16:40
Real Name: Robert Mason
Location: Australia
Contact:

Solid Mounting A Motor

Post by Rob M » Thu, 29 Jan 2009, 05:43

I am mounting a 11" motor directly to the gearbox mountings in a Volvo 960, with engineering approval. It is best to avoid using the aluminium castings on the ends of the motor as they are not designed to withstnd some of the shock loads that might occur. I drilled and tapped into the steel barrel of the motor which has more than enough strength for the purpose.
I dont believe vibration is going to be a problem. There might be a bit of noise tranferred to the floor panel from the diff and wheels but my guess is it will be minimal. I"ll keep you posted.

User avatar
EV2Go
Senior Member
Posts: 2059
Joined: Wed, 16 Jul 2008, 00:21
Real Name: Paul
Location: Brisbane 1963

Solid Mounting A Motor

Post by EV2Go » Thu, 29 Jan 2009, 19:05

After many hours of tossing and turning trying to get to sleep last night I decided to get up and put some ideas down on paper. As much as it would probably look a bit neater, I think putting the motor in the engine bay may not be such a great idea and have gone back to my original idea of mid mounting the motor. The mini has two separate sub frames and I have some serious reservations about the chassis being able to handle the twist in an unsupported body. By the time you add the extra weight and expense of putting in a full roll cage to tie the two sub frames together it might be easier to choose another donor car.

If I mid mounted the motor using a TransWarp 11 motor which uses a std 1350 uni joint, and bolt the diff directly to that, there would be very little opportunity for it to flex the body, since both the motor and the diff would be on the same boxed parallel rails.

Since the whole rear chassis would have to be redone for the independent rear suspension, there is no reason why I couldn’t extend the sub frame into the back seat area (removing back seat) to form the mounting rails for the motor, and build those rails into the battery box which would tie into both sides of the car.

Trying to budget this project with some kind of financial control, I was thinking of running the motor at 72v with either SLA or LFE until the Aussie dollar picks up again and makes batteries a little more affordable at which time I would like to step it up.

User avatar
Electrocycle
Senior Member
Posts: 985
Joined: Sun, 19 Oct 2008, 20:23
Real Name: Andrew
Location: Sydney
MSN: dumhed@dumhed.com
Contact:

Solid Mounting A Motor

Post by Electrocycle » Thu, 29 Jan 2009, 20:47

I'd go for a higher voltage pack at lower amp hours rather than lower voltage.

I think at 72v your top speed will be too limited.
The important thing is the kilowatt hours of the battery pack, and the higher voltage you have the wider your usable rpm range, so you can run lower gearing and get better performance and efficiency at low speeds.
The Engine Whisperer - fixer of things

User avatar
EV2Go
Senior Member
Posts: 2059
Joined: Wed, 16 Jul 2008, 00:21
Real Name: Paul
Location: Brisbane 1963

Solid Mounting A Motor

Post by EV2Go » Thu, 29 Jan 2009, 21:12

If I understand you correctly the higher voltage will allow the motor to produce more torque allowing the use of taller (closer to 1:1) diff gears?

Wouldn’t a Warp 11 produce sufficient torque to move a mini with tall diff gears, say 2.75:1 or 2.5:1 even at 72v?

I was thinking if I went lithium I would go 23 x 3.2v 160Ah (23 x 5.6kg = 128.8kgs) to get ”acceptable “ performance but still get decent distance, and down the track when the dollar improves buy more of the same.

Are you saying I would be better of going for something more like 43 x 3.2v 90Ah (43 x 3kg = 129kgs) although that would probably work out dearer?

User avatar
Electrocycle
Senior Member
Posts: 985
Joined: Sun, 19 Oct 2008, 20:23
Real Name: Andrew
Location: Sydney
MSN: dumhed@dumhed.com
Contact:

Solid Mounting A Motor

Post by Electrocycle » Thu, 29 Jan 2009, 21:24

it depends on the motor and controller, so you're usually limited to a maximum of 144v, but 144v at 100Ah will be better than 72v at 200Ah.

The higher voltage means higher possible rpm, so you can use shorter gearing for the same top speed - which means more torque to the wheels at low speed (the motor will make the same torque at low rpm as it'll be limited by the controller current limit).

If you run taller gearing and lower voltage you'll need to run massive current to get decent takeoff torque, and that will heat the motor up and be much less efficient so you'll end up with less range.
The Engine Whisperer - fixer of things

User avatar
woody
Senior Member
Posts: 1713
Joined: Sat, 21 Jun 2008, 02:03
Real Name: Anthony Wood
Location: Mt Colah

Solid Mounting A Motor

Post by woody » Thu, 29 Jan 2009, 21:35

If you went for a small capacity / high output LiFePO4 battery like the EVPST-10Ah which are about US$25 each in china, you could still go for 144V, be able to deliver 300A continuous (600A peak) to the controller (40kW - 70kW), if you have a string of 45 pairs of them.

All you sacrifice is range (24km @ 100Wh/km @ 80% DoD).

So enough juice to get to work and back (just).

The benefits are weight (50kg), cost (US$2400 FOB Ghangzhou), size (25 Litres).

cheers,
Woody
Planned EV: '63 Cortina using AC and LiFePO4 Battery Pack

User avatar
Taffy
Groupie
Posts: 238
Joined: Mon, 23 Jun 2008, 15:12
Real Name: Taffy Flynn
Location: Melbourne
Contact:

Solid Mounting A Motor

Post by Taffy » Thu, 29 Jan 2009, 22:48

Woody, slightly off topic. But is it possible to parrallel these batteries with slower discharge ones? More to the point is it a sane idea.

MODERATOR EDIT: Taffy, Ive started a new topic here so we dont end up off topic: new topic
Last edited by antiscab on Thu, 29 Jan 2009, 14:34, edited 1 time in total.

User avatar
EV2Go
Senior Member
Posts: 2059
Joined: Wed, 16 Jul 2008, 00:21
Real Name: Paul
Location: Brisbane 1963

Solid Mounting A Motor

Post by EV2Go » Thu, 29 Jan 2009, 23:21

Electrocycle wrote: it depends on the motor and controller, so you're usually limited to a maximum of 144v, but 144v at 100Ah will be better than 72v at 200Ah.

The higher voltage means higher possible rpm, so you can use shorter gearing for the same top speed - which means more torque to the wheels at low speed (the motor will make the same torque at low rpm as it'll be limited by the controller current limit).

If you run taller gearing and lower voltage you'll need to run massive current to get decent takeoff torque, and that will heat the motor up and be much less efficient so you'll end up with less range.


Ok I am with you now... running lower diff gears increase torque multiplication, but you still get the same top end speed because you can rev it harder.

Would I be better of running 12 x 12v SLA if trying to do it on the cheap for now?

Hey those batteries Woody pointed out would be nice in your bike...

Woody if you have 2 x 10Ah in parallel would that lower the C since the bigger capacity batteries have lower C ratings?

bga
Senior Member
Posts: 492
Joined: Mon, 01 Sep 2008, 19:27
Real Name: Bruce Armstrong
Location: Perth WA

Solid Mounting A Motor

Post by bga » Thu, 29 Jan 2009, 23:33

There is likely to be a considerable amount of high frequency vibration transmitted into the body, which will resonate and make it noisy inside.
I would suspect that bolting a motor (and gearbox) directly to the body would be surprisingly noisy.

ACMotor's comment about structural loading is a valid point of caution. The longitudinal bolts and flange plate on most motors aren't designed to do more than hold the motor together. Placing it in the load path will likely result in deformation, internal mis-alignment, broken bolts and threads, bearing problems and a short service life.

Most ICEs are designed to fulfill the structural role of coupling the gearbox and engine to the body mounts. The emotor requires an external frame to fulfill this role.

A recent discussion with a vehicle engineer suggested that the motor frame also has to be stiff so that it can support the free end of the emotor, and not flex sufficiently to stress the motor. He suggested triangulated members would be good for rigidity and weight.

It would be a good experiment to replace the engine mounts with metal blocks and see what it sounds like.

User avatar
EV2Go
Senior Member
Posts: 2059
Joined: Wed, 16 Jul 2008, 00:21
Real Name: Paul
Location: Brisbane 1963

Solid Mounting A Motor

Post by EV2Go » Fri, 30 Jan 2009, 00:00

If I went with a mid mount construction I don’t think it would be that hard to rubber mount the motor. The only reason I was contemplating using the end plates was due to limited space and even then I thought of a better way of getting around that.

I have seen some rather large straps that go around the motor (I think Les is using one on the 4WD he is converting) just need to use two of those one at each end and mount the engine mounts to that.

From a load perspective I don’t think driving the diff directly off the motor would be all that different to making up a coupling up and driving a gearbox that has been done numerous times before. Just as long as the alignment is spot on and the parallel rails are made sufficiently sturdy that they don’t flex.

bga
Senior Member
Posts: 492
Joined: Mon, 01 Sep 2008, 19:27
Real Name: Bruce Armstrong
Location: Perth WA

Solid Mounting A Motor

Post by bga » Fri, 30 Jan 2009, 03:21

Agreed,

There are lots of ways to skin a cat, or mount a motor.

Given that a Mini is very compact, deviating from the original drive arrangement and componments is likely to be a big headache.
The Mini won't take a very big motor without a lot of re-engineering, nor will it take a lot of battery because of the low GVM.

Here's a mini conversion that looks like a nicely executed effort.

Whatever it is, the mechanical stuff is hard to do and expensive, minimising this is important to the success of a project.

Einstein:
Things should be made as simple as possible, but not any simpler.


User avatar
EV2Go
Senior Member
Posts: 2059
Joined: Wed, 16 Jul 2008, 00:21
Real Name: Paul
Location: Brisbane 1963

Solid Mounting A Motor

Post by EV2Go » Fri, 30 Jan 2009, 20:15

Yes I saw that mini at the EV field day, it is a very neat conversion, problem is I have been wanting to perform a bit of a radical conversion on a mini for a very long time (since the early 90’s).

I originally wanted to build a V4 Chev for one and rear wheel drive it, but since the only people who used the alloy V4 Chev were speedway guys I had a lot of trouble tracking one down.

I managed to finally track one down but the crank had been blown out the bottom of the motor taking the bearing caps with it, and it was going to be too much hassle to rebuild it.

I know converting a mini to RWD isn’t the simplest of operations but I like a challenge. After helping Kearon in the latter half of his conversion, a standard conversion like the brown mini would be almost boring.

I already have sufficient funds to do the job, I am just trying to justify spending that money when I could buy a brand new 2009 model vehicle for less money.

fuzzy-hair-man
Groupie
Posts: 118
Joined: Wed, 12 Nov 2008, 16:40
Location: Canberra

Solid Mounting A Motor

Post by fuzzy-hair-man » Fri, 30 Jan 2009, 21:11

I know I've vaguely said it before but....

have you seen some of the rwd minis on (the motors won't be much use but how they did the rear subframes could be useful):

16 value mini forums

Do a search I found a couple but it seems there are lots more.

and RWD motorbike and other powered minis

Z Cars motorbike and other RWD minis

The RWD Volvo powered one might be interesting to get some ideas for a subframe. Image

This should give some pretty reasonable ideas for RWD minis and subframes of course just because it passes in the UK...
bga wrote:nor will it take a lot of battery because of the low GVM.
AFAIK the GVM of a mini is somewhere near 1050 kg for the utes and vans, I haven't seen a GVM for the ordinary mini but AFAIK the suspension is exactly the same so I don't think they should be any different, given that the curb weight is 650kg or so this gives something like 400kg for batteries, motors, and people the engine and gearbox is also quite heavy so you gain a fair bit there too. Space is a problem but given EV2Go is resolved to loosing the back seat anyway there should be enough room available I'd think.

Putting the engine and batteries in the back is significantly changing weight distribution from standard though seeing as 1 person can lift the rear wheels of the ground normally. Image

There's some weight calculations I did when I was thinking about minis here: (bottom of the first page)

Some very rough mini weights
Incidentally re: the disputed weight of the mini engine and gearbox I found a couple of other sources on that 16vmini forum that say it's around the 150kg mark. Image

If you went the whole hog and got a fibreglass front doors bonnet boot etc (readily available) you might be able to get the weight down even further but by this stage I guess it's getting kind of desperate. Image
Last edited by fuzzy-hair-man on Fri, 30 Jan 2009, 10:26, edited 1 time in total.

User avatar
EV2Go
Senior Member
Posts: 2059
Joined: Wed, 16 Jul 2008, 00:21
Real Name: Paul
Location: Brisbane 1963

Solid Mounting A Motor

Post by EV2Go » Sat, 31 Jan 2009, 00:13

Thanks FHM, looking at some of those mini shots what I am contemplating would be a walk in the park compared to the level of modification some of them have gone to. Some of those rebuild were complete chassis replacements...

I have already put together some preliminary designs to replace the rear sub frame and anticipate it would be a fairly straight forward affair (as straight forward as chassis mods get). It would be more like a rear half chassis replacement.

150kg doesn’t sound entirely unrealistic... Despite its size the block is cast and the gearbox isn’t overly light. 150kg might be a bit of a stretch, but I was only counting on the weight of the engine / gearbox covering the weight of the TransWarp 11 motor (which is about 110kgs)

My old mini weighed 660kgs without me, so if I can keep battery weight down I should have no problems coming in under 1050kgs.

The picture Goombi posted here of the yellow motor / diff was what I had in mind for the drive train. viewtopic.php?t=813&start=2
Last edited by EV2Go on Fri, 30 Jan 2009, 14:17, edited 1 time in total.

bga
Senior Member
Posts: 492
Joined: Mon, 01 Sep 2008, 19:27
Real Name: Bruce Armstrong
Location: Perth WA

Solid Mounting A Motor

Post by bga » Sat, 31 Jan 2009, 03:20

Hey EV2Go,

The yellow motor looks too pretty to hide under the car Image

A challenge is the name of the game. Maybe 'tetris'?

I was thinking the batteries are going to be a particular form of entertainment since 'light weight' and 'high power' don't like occupying the same space.

And a few days before that, I had another thought :-
Battery tools, particularly the LiIon types, are starting to challenge plug-ins. How long will it be before battery powered will be the choice for savaging timber or metal?
Perhaps it's already here in RC model airplane power packs.

Cheers
BGA

User avatar
EV2Go
Senior Member
Posts: 2059
Joined: Wed, 16 Jul 2008, 00:21
Real Name: Paul
Location: Brisbane 1963

Solid Mounting A Motor

Post by EV2Go » Mon, 02 Feb 2009, 20:44

Over the weekend I spent a fair amount of time looking at cut away views of the mini and I think what I am proposing is going to be far more challenging than first thought in terms of available space, far from impossible but hard enough to offer me a serious challenge.

If space is as limited as I think it is going to be the TransWarp motor, although the easiest to join to a 9”diff via a 1350 uni is not going to be an option. I will need to use a setup similar to that yellow motor and diff.

Anyway I was speaking a fellow Ever over the weekend and he mentioned that he knew of someone who had a mini body going cheap, so all going well this may turn into a reality rather than just talk and speculation.

Yes BGA getting enough battery capacity is going to present a real challenge...

Goombi
Senior Member
Posts: 532
Joined: Sun, 10 Aug 2008, 17:59
Real Name: Eugen
Location: Gympie

Solid Mounting A Motor

Post by Goombi » Fri, 13 Feb 2009, 09:15

Hello EV2Go,
Re- Motor rubber mountings--If the gearbox is on rubber so should the motor be. Not only with a ring around the body but also mounted and screwed to the Motor body . Either from the front plate preferably) of where the coil bolts are. The vibration is always in the motor and through gearbox with both parts cushioned it will give you satisfaction.
Direct mounted motor and rubber supported gearbox ..not very friendly affair. You will need good engine mounts as the motor is fairly heavy. And you will pass inpection.. no problem.....Think of the torque,,,,,
Good luck with your project--Eugen
PS. Beware of cutting mini frame or welding They are extremly light gauge material-or altering subframe making it rear wheel drive etc.
You could be quite right-- perhaps another donor vehicle...
Last edited by Goombi on Thu, 12 Feb 2009, 22:31, edited 1 time in total.

User avatar
EV2Go
Senior Member
Posts: 2059
Joined: Wed, 16 Jul 2008, 00:21
Real Name: Paul
Location: Brisbane 1963

Solid Mounting A Motor

Post by EV2Go » Fri, 13 Feb 2009, 20:30

Hi Eugen,

Not sure you fully understand what I was trying to achieve. The is no gearbox involved in the proposed vehicle... Basically what I am contemplating is taking a Warp11 and bolting it directly up to a diff (most likely a 9” Ford diff). There was a picture around the forum of a yellow motor with a diff connected directly (as in bolted together as one structure) this would then sit with the motor in the back seat area and the diff part in the rear sub frame area. When I started this thread I was contemplating putting just the motor part in the front sub frame and running a tail shaft back to the diff. I have since abandoned that idea because the mini is not designed for structural twist and adding a roll cage to do that defeats the purpose.

I have been in contact with an ex work colleague who has contacts within the drag racing community (as in he races nitro based cars himself) Ideally if I can get my hands on a shortened 9” diff housing out of a dragster or similar that might make a suitable starting point for the rear diff, otherwise I will need to buy and old complete diff and shorten the housing myself. Being that I used to work at Superformance where we built custom 9” diffs I am fairly well versed with what is required to make one from scratch.

The rear sub frame would obviously be ditched in favour of a complete new one, but if you have ever looked at a mini rear sub frame you will realise how simple they are. In addition to the rear sub frame I would be looking to extend the tube work into the back seat area where the motor would be mounted forming a solid chassis link between motor and diff eliminating and chassis twisting.

If I mount both the motor and the diff solidly to the chassis rails I would need to rubber mount the chassis to the body. Take a look under any late model Japanese car and that is exactly what they do, the diff is bolted firmly to the rear sub frame and the sub frame is rubber mounted to the body. Same idea but including the motor into the equation.

User avatar
Electrocycle
Senior Member
Posts: 985
Joined: Sun, 19 Oct 2008, 20:23
Real Name: Andrew
Location: Sydney
MSN: dumhed@dumhed.com
Contact:

Solid Mounting A Motor

Post by Electrocycle » Fri, 13 Feb 2009, 22:10

you could always run a torque tube down the middle if you have the engine in the front :)
The Engine Whisperer - fixer of things

Post Reply