Mid Motor vs Rear motor

BenG · #1 06-10-2006

Ok, now I really want your opinions. IS it best to have a motor mounted on the rear? Or in X6 style? This is importanty, as I am ordering my carbon fibre and fret saw, and want to know which you lot prefer. Admittedly rear mounted ( less modifying of the tranmission)would be easier for me, but I'll see what you lot come up with

DCM · #2 06-10-2006

I personaly feel it is far better to have the weight infront of the rear axle, but only just in front, I don't personaly feel the motor is the right thing to be places there though.

boomerang · #3 06-10-2006

I would say, for straight on traction, the motor should be on the back, for increased cornering speed, put in front of the raer axle...so it depends on the track and the traction of it

greez from switzerland

Maurice

BenG · #4 06-10-2006

Thanks Maurice I think I am going to make it a rear mounted motor, and make a carbon fibre cahssis/top deck, using saddle packs

Chris Doughty · #5 06-10-2006

I have thought so much about many layouts etc...

let me just say, EVERYTHING is a compromise, you just need to choose key things that you want your car to do that you think would generate the fastest race time.

in a simple term, if you favour power on steering, the mid-motor would be good. at loss of drive and bump riding.

if you want your car to have superb drive and rear end in between corners, then rear motor of some description would work best.

that is a very very broad example.

BenG · #6 06-10-2006

Quote:

Originally Posted by DoughtyUK.net

I
if you want your car to have superb drive and rear end in between corners, then rear motor of some description would work best.

that is a very very broad example.

I like that explanatation chris, its very simple, thanks matey

I think, firstly for simplicity, and secondly, for compatability with B4 parts( asI want to race this next year) I think rear mounted motor will simply be much easier. Secondly, I prefer a car that rides bumps better, as I am a touring car racer

so less bumps is good

OldTimer · #7 06-10-2006

My thoughts are if you are running on a low grip surface then rear motor is the only way to go, if its med/high grip then mid motor (with the motor as close as poss to the diff) is the answer.

But with the B4 and CR why make you own rear motor car ? as these cars are very refined rear motor cars, but mid motor is a whole new ball game

Chrislong · #8 06-10-2006

Do you have idea's of how to change the weight distribution and improve the chassis?

DCM · #9 06-10-2006

Quote:

Originally Posted by Chrislong

Do you have idea's of how to change the weight distribution and improve the chassis?

Yes, if you are going to go mid motor, you still want weight over the rear, and I don't think the motor is the heaviest part out of components is it.....

Northy · #10 07-10-2006

Quote:

Originally Posted by DCM

Yes, if you are going to go mid motor, you still want weight over the rear, and I don't think the motor is the heaviest part out of components is it.....

Mmmmmm, I think me and you are on the same wavelength here DCM

Now only if I had some spare time to work on my 2wd car......

G

Richard Lowe · #11 07-10-2006

I think a lot of people miss the point of turning the gearbox round in a 2wd.
IMO the 'standard' layouts have the weight distribution about nailed, but by having the cells down the middle and the motor hanging out at the back gives you a high polar moment of inertia. In an ideal world you want all your weight concentrated around the CG, which is what the mid motor layout gives you.

So long as you don't move the weight forward (ahem X6

) I can't see how a mid motor car would have any less drive out of corners than a normal 2wd. It should feel much more planted and composed, feel more agile and suffer less pendulum effect when the back steps out.
Of course I could be taking rubbish

I'm going to run mine for the first time tonight at Teeside so I'll have to see if it behaves how I think it will.

What have you got planned DCM? Lemmie guess, saddle cells just in front of the rear axle with the motor in the middle of the car and a belt to the back?

Northy · #12 07-10-2006

Rich, I rwally think you need totake your car to York and see how it performs on grip level changes!

IMHO, any car will go well at Teesside due to the huge amount of grip.

Hope it goes well though.

G

DCM · #13 07-10-2006

Quote:

Originally Posted by Richard Lowe

What have you got planned DCM? Lemmie guess, saddle cells just in front of the rear axle with the motor in the middle of the car and a belt to the back?

Maybe... only downside with that route, is you REALY need to go for a new chassis right away, and means a lot of machining work...... who knows...

Richard Lowe · #14 07-10-2006

Yeah but you already have plenty of rear end's available, Yoke BX for example.

Apart from the chassis nothing really to make either as you could use the whole rear end from the BX. If you want the B4 front end you could do like I'm planning to and screw the GT2 front sub-chassis to the main chassis and use a standard B4 front end.
You'd have to make a different motor mount though as the standard BX parts put the motor a bit far forward, and the top deck mount looks a bit high to mount straight to the GT2 sub-chassis.

DCM · #15 07-10-2006

yeah, once you go down that route, it gets a little complicated, but the issue I see with flipping the box round, is you tend to throw out the camber links and stuff at the rear.

Are there any detail pics of the BX rear end?

super__dan · #16 08-10-2006

FYI of anyone that's interested,

Last night at Teeside we measured the front and rear weight distributions on some scales in a fair accurate way I think.

My X6 ready to run was 64% rear, 36% front. Rich's XXX-Cr was 67% rear, 33% front.

To note, my car had 15g on the front bulkhead, none extra at the back. Rich's CR was much modded to moe the weight forward i.e. cells forward and 40g in the front.

Rich's car ptoto car looked good I thought early doors, unfortunatly he broke a wishbone and no-body had any spares. My car was terrible early doors but came a long way and by the final was really good. I did drive like a tool though and kept hitting the same thing ALL night. Chris X6 looked pretty good all night and particularly good when being thrashed (as only Chris can) in the final.

Chrislong · #17 08-10-2006

Me?..... Thrash?...... NEVER!

It paid off though!

KBRacing · #18 08-10-2006

Of what I can say the X - 6, is easy to drive then my Ass. B4.
Because the mid motor X - 6 style, drivers more like a 4wd then a 2wd.

elvo · #19 09-10-2006

Because the torque reaction from the motor pulls the weight AWAY from the rear axle now, that's why. Ideally, for a mid-motor car, you'd want 2 idler gears, and the motor spinning tht other way...
I agree 100% with the rest of your post though. Oh, and I have to give you credit in advance for an idea I'm about to steal :-D A few months ago, I made some CAD sketches of a mid-motor, saddle-pack B4, much like your contraption. But I was going to mill my own toe-in blocks. Using BJ4 toe-in blocks is way easier! They have the right geometry, too.

Quote:

Originally Posted by Richard Lowe

I can't see how a mid motor car would have any less drive out of corners than a normal 2wd.

Chris Doughty · #20 09-10-2006

Quote:

Originally Posted by elvo

Because the torque reaction from the motor pulls the weight AWAY from the rear axle now, that's why. Ideally, for a mid-motor car, you'd want 2 idler gears, and the motor spinning tht other way...
I agree 100% with the rest of your post though. Oh, and I have to give you credit in advance for an idea I'm about to steal :-D A few months ago, I made some CAD sketches of a mid-motor, saddle-pack B4, much like your contraption. But I was going to mill my own toe-in blocks. Using BJ4 toe-in blocks is way easier! They have the right geometry, too.

definately, 2 idler gears would be ace. it would get the motor 'snap' in the same direction as the wheel 'snap'

think how much control you would have in the air!