Suitable FWD Gearbox

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

Suitable FWD Gearbox

Post by EV2Go »

If you were looking for a FWD gearbox that you wanted to bolt up to say a Warp 11, and you were going to put it into the back of a car with a very narrow track like say a mini, and it needed the following specs what would you consider?

reasonably strong
the diff output to be as far forward as possible (because of the narrow track, would need to try centre the output to keep axles as close as possible to equal)
very small external dimensions
light weight (which shouldn’t be too much of an issue as most FWD gearboxes are alloy)
Available in Australia

something like this maybe http://media.gmcanada.com/division/2005 ... MN5LoR.jpg
Last edited by EV2Go on Fri, 14 Aug 2009, 11:05, 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

Suitable FWD Gearbox

Post by EV2Go »

Tritium_James
Senior Member
Posts: 683
Joined: Wed, 04 Mar 2009, 17:15
Real Name: James Kennedy
Contact:

Suitable FWD Gearbox

Post by Tritium_James »

Wow, that doesn't look cheap! Guess that wasn't on your list of requirements though Image
User avatar
EV2Go
Senior Member
Posts: 2059
Joined: Wed, 16 Jul 2008, 00:21
Real Name: Paul
Location: Brisbane 1963

Suitable FWD Gearbox

Post by EV2Go »

I am terrified to ask but it would be perfect for the back of the mini. I have sent him an email but I had better be sitting down when he comes back with the price.
Benonymous
Groupie
Posts: 92
Joined: Fri, 14 Mar 2008, 20:12
Real Name: Ben Roberts

Suitable FWD Gearbox

Post by Benonymous »

I agree on the $$$ issue with this motor/transmission unit. When I see acres of CNC'd alloy my first reaction is "'spensive!" If you want a FWD gearbox that can handle the torque of the electric motor, maybe a Mitsubishi unit from a V6 Verada or similar would be strong enough. It would depend on the weight of the completed vehicle though.
User avatar
EV2Go
Senior Member
Posts: 2059
Joined: Wed, 16 Jul 2008, 00:21
Real Name: Paul
Location: Brisbane 1963

Suitable FWD Gearbox

Post by EV2Go »

Problem is lack of space... there is nowhere enough room to stick a big motor and gearbox in a Mini without it pushing the gearbox way over to one side. The brown mini with the 8” and the Suzuki gearbox only just fits with a modification to the sub frame on the motor side to clear the non gearbox end shaft, so there is no way something bigger will fit without pushing the gearbox ( mainly diff output) further over to one side.

Without something like what he has machined up there is just no way to fit a big motor in a Mini without extensive body / chassis modifications. I thought about turning the motor North / South adding a tail shaft and IRS rear end but that is a crap load of reengineering. The cradle he has made would be ideal for the back of a Mini.

Looking at the design though I wonder if it really needs to be that complex... You can get a Quaffe or similar chain driven diff, make a few end plates to support the diff / mounting points and Bob’s your uncle.

http://www.bing.com/images/search?q=qua ... Fxpin4.jpg

Still haven’t got a price yet but definitely agree all that CNC work look MEGA expensive.

Edit:
Instead of a chain you could always use straight cut gears (lower drag, greater noise but no trying to drive the diff centre sideways) but that would mean inclosing the gears to lubricate them.
Last edited by EV2Go on Mon, 17 Aug 2009, 12:04, edited 1 time in total.
Tritium_James
Senior Member
Posts: 683
Joined: Wed, 04 Mar 2009, 17:15
Real Name: James Kennedy
Contact:

Suitable FWD Gearbox

Post by Tritium_James »

EV2Go wrote:Instead of a chain you could always use straight cut gears (lower drag, greater noise but no trying to drive the diff centre sideways) but that would mean inclosing the gears to lubricate them.
This is exactly the setup in the Porsche: quaife diff with a custom 2-stage reduction geartrain. Motor sits E-W. Custom one-off gearing and mech stuff isn't cheap though, I think there was about 40k of work/bits went into the box in the Porsche...
User avatar
EV2Go
Senior Member
Posts: 2059
Joined: Wed, 16 Jul 2008, 00:21
Real Name: Paul
Location: Brisbane 1963

Suitable FWD Gearbox

Post by EV2Go »

They must have been some expensive bits in there somewhere...

I priced up a Quaife diff a couple a months ago and they quoted $1500 AU plus freight from NZ, could use a LSD centre out of just about anything really.

Shouldn’t need to have gears custom made up, there is always some odd bit of machinery that can be modified to fit or adapted.

Bit of creativity could see it being made for a couple of thousand.
Tritium_James
Senior Member
Posts: 683
Joined: Wed, 04 Mar 2009, 17:15
Real Name: James Kennedy
Contact:

Suitable FWD Gearbox

Post by Tritium_James »

Not when it's got to run at 12krpm continuous like in the Porsche, though!
User avatar
EV2Go
Senior Member
Posts: 2059
Joined: Wed, 16 Jul 2008, 00:21
Real Name: Paul
Location: Brisbane 1963

Suitable FWD Gearbox

Post by EV2Go »

I keep coming back to something like this for simplicity viewtopic.php?t=851
but I can’t see it fitting into the back of a mini without sitting the motor almost vertically and that lifts the bulk of the weight up higher. Also concerned what effects that would have on the bearings in the motor and diff.
Tritium_James
Senior Member
Posts: 683
Joined: Wed, 04 Mar 2009, 17:15
Real Name: James Kennedy
Contact:

Suitable FWD Gearbox

Post by Tritium_James »

I reckon it's probably hard to beat a chain drive reduction onto a quaife type diff for simplicity. Lubrication is fairly simple, and there's no precise tolerances required as there are with a gear reduction.
User avatar
Electrocycle
Senior Member
Posts: 985
Joined: Sun, 19 Oct 2008, 20:23
Real Name: Andrew
Location: Sydney
MSN: dumhed@dumhed.com
Contact:

Suitable FWD Gearbox

Post by Electrocycle »

even a large toothed belt drive to the diff would work
Last edited by Electrocycle on Mon, 17 Aug 2009, 17:14, 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

Suitable FWD Gearbox

Post by EV2Go »

That had crossed my mind something like a Harley.

BTW got a response to my enquiry on that CNC machined motor cradle and diff.... $40K!

Ok I don' think we will be going that way.
Last edited by EV2Go on Tue, 18 Aug 2009, 07:01, edited 1 time in total.
HeadsUp
Groupie
Posts: 265
Joined: Sat, 28 Feb 2009, 09:13
Real Name: Mark W
Location: Sydney

Suitable FWD Gearbox

Post by HeadsUp »

Electrocycle wrote: even a large toothed belt drive to the diff would work


i did some study on toothed belts a while back for a mining application , and their power transmission potential is quite poor

Tritium_james would need nearly 4 inches of belt width for 200 kW of drive

prefer the Satria approach mentioned above with a diff direct mounted to the motor , except i would probably use something like a skyline IRS front diff

( because the motor and diff face to the rear in the porsche the helical worm gears will be spinning the wrong way ( innefficient gear cut , and a bit noisier ) if you used a rear diff in that setup


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

Suitable FWD Gearbox

Post by Electrocycle »

some belts must be pretty good. Superchargers on drag cars are putting many hundreds of kw though a ~100mm belt.
They don't do it for a massively long time, but I don't think they change the belt every run.

Chain is the easy option, but a bit louder and messier.
The large bike belt drives seem to be very reliable, and might be large enough for a mini (we're already talking two belts for a dual motor setup)
The Engine Whisperer - fixer of things
AMPrentice
Senior Member
Posts: 401
Joined: Tue, 05 Aug 2008, 19:30
Location: down south

Suitable FWD Gearbox

Post by AMPrentice »

Mitsu boxes are very strong and cable operated for any mounting you desire even rwd midship layout like an MR2 otherwise I recommend the many 2.4 litre Pintara fwd SSS and similar specced Nissan Pintara with the factory vicous LSD, Super strong and $120 dollars the lot at pick a part wreckers.
http://www.zeitgeistmovie.com/

No Queen, No Prime Minister, No hierarchical system to break down our communities
Never vote Labour, Liberal or Maggots like them.
Post Reply