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Pro Motive Torque Steer


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#1 R1mini

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Posted 04 July 2008 - 07:12 PM

Just to make things clear this is not slagging of the promotive conversion in any way!


The promotive setup uses standard length mini driveshafts I understand, without going through the posts from memory torque steer is evident on this conversion, I'm wondering if it's worthwhile redoing part of the cradle on my R1 fwd mini to get equal length driveshafts, or should I just get the thing done! Probably would take about a day to make the alterations

Any advice would be gratefully received

Cheers
David

Edited by R1mini, 05 July 2008 - 08:40 AM.


#2 YIANO

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Posted 08 July 2008 - 02:41 AM

the reason the driveshafts are not equal on this conversion or indeed the standard A series engine installation is that the diff doesnt allow for equal length driveshafts due to its location ,and the position of the r1 engine within the frame .Also the diameter of the driveshafts will always be a limiting factor due to front subframe design and so could not be increased significantly to address the enequal length issue. Ultimately with any front engined mini producing upwards of 150 bhp torque steer will always be a factor irrespective of engine brand. Its more to do with suspension design and mechanics
I dont think youll easily move the diff central to allow your equal length driveshafts as the engine driveline components all line up from the bikes sprocket back.
so youd have to move the diff assuming the engine is no longer in the way and then machine a longer input shaft for the diff ,this would have to be supported via bearings and at 12000 rpm i sense a vibration issue leading to component failure.
A far more sensible solution to the issue of torque steer would be to maximise your suspension settings in order to try to balance the problem particularly caster,good quality components with correct bushings and setup by a professional will decrease the torque steer issue to a comfortable level.
At the end of the day you could use torque steer as a safety mechanism in this instance and back off before you slide off the road or get nicked !!
hope this helps !

Edited by YIANO, 08 July 2008 - 02:49 AM.


#3 R1mini

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Posted 08 July 2008 - 11:17 AM

Sorry my first post seems to suggest I have a pro motive kit and I'm asking regarding modifying that, I haven't got a pro- motive kit.

I'm currently in the process of making my own fwd R1 conversion and was looking to see if it was worthwhile moving the engine cradle within my subframe to give absolutely equal driveshaft lengths, I placed the engine centrally in the subframe to have as much height above the carbs originally, not concerning myself to much with the different length of the driveshafts as I thought that torque steer wouldn't be a problem with limited torque. A few people have now got the pro-motive conversions on the road and have mentioned some torque steer issues and with my driveshafts they are more unequal than the mini ones so I may suffer from even more torque steer.

A few pictures would help, as you can see the cradle sits in a heavily modded subframe, the cradle can be offset fairly easily with a bit of re fabrication to sit with equal length driveshafts, question is it worth pulling it apart to alter the cradle

Cheers
David

Edited by R1mini, 30 May 2010 - 03:41 PM.


#4 Jammy

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Posted 08 July 2008 - 11:25 AM

Is it possible for you to fabricate some sort of half shaft arrangement? Best of both worlds then.

#5 Ethel

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Posted 08 July 2008 - 11:54 AM

I'm of the impression that torque steer is at least partly attributable to the different geometry in the driveshaft joints that's inevitable with odd length shafts unless the diff and hubs are all on the same axis.

Equal length shafts seem a creditable solution. Possibly altering the axis of the diff could equal out the angles too?

#6 supermotolee

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Posted 08 July 2008 - 07:46 PM

use a quaife and a nice new rack (i had an old sloppy one on before) mines perfect now even on bumpy roads its a one handed affair

#7 roofless

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Posted 08 July 2008 - 08:58 PM

just to clarify on some of my old posts - My torque steer was entirely down to issues with steering rack - shifty will vouch for this - since sorting its massively improved and torque steer is now minimal, or at least comparable to any other high powered mini.

compared to the 2 vauxhall powered minis I had a chance to drive, it is considerably better, and compared to the vtec car drive i had, its nowhere near as bad.

dont loose sight of the fact that people like me ( not all pro-mo customers ) go for the conversion due to its simplicity and effectiveness, the fact it uses your original driveshafts was a big decider for me, and i think in some ways helps make this the most cost effective route to high powered bike power fun.

If I had the time, welding skills and patience you demonstrate I would have loved to have a go from scratch, and i admire you for that - but in my world the small amount of torque steer I now get is a small pay-off against the simplicity and ease of utilising the original drive shafts.

Many of your posts have been suggestive that you are utilising a pro-mo kit, but i guess its because you are basing your research on their product, in fairness i would do the same, but I think its also only fair that you are much clearer in pointing out that you are doing this off your own back, and its your own engineering and problem solving skills being put to the test.

Your progress is impressive, and again i wish i had the skills / brass dangly bits to have tried this as a DIY project :errr:

good luck, but in summary - try it with the original driveshafts and see how you get on...............

PS I forgot to mention - 14" wheels and 4 year old tyres probably need addressing in my case also, and suspension geometry would fail a multiple choice cookery exam - its high on our list to get sorted and may completely eradicate the remaining issues I have.

Edited by roofless, 08 July 2008 - 09:05 PM.


#8 Shifty

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Posted 08 July 2008 - 09:03 PM

I can most certainly vouch for this, actually having a steering rack thats attached to the car made an incredible amount of difference to roofless!!

The torque steer was drastically reduced(as was the smell of fear coming from the passengers seat!!)

#9 roofless

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Posted 08 July 2008 - 09:07 PM

I can most certainly vouch for this, actually having a steering rack thats attached to the car made an incredible amount of difference to roofless!!

The torque steer was drastically reduced(as was the smell of fear coming from the passengers seat!!)


sorry shifty - I am learning to do bolts up properly - sort of. :errr:

#10 R1mini

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Posted 09 July 2008 - 10:52 AM

Thanks everyone, that's cleared things up.

I'm asking about the Pro-Motive specifically because it has unequal length driveshafts and it's the only bike engined fwd kit I know to reach the market and sell.

I was up for a Pro-Motive kit several years ago when Darren turned up at Castle Combe for the first time but after waiting for quite a while I decided to start making my own, just after that the kit turned up on the market and I'm still mucking about with my own version, what a pain.

Cheers
David

#11 Ethel

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Posted 09 July 2008 - 11:04 AM

use a quaife and a nice new rack (i had an old sloppy one on before) mines perfect now even on bumpy roads its a one handed affair


Interesting, how effective is a Quaife when the problem is the torque at the diff outputs may be equal but the torque on the tyres isn't?

#12 supermotolee

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Posted 14 July 2008 - 09:43 AM

the quaife makes it nice to drive ethel, its filled with spells, wizzards and magic

#13 Rosslin Racing

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Posted 14 July 2008 - 03:50 PM

JKD used to make a bolt on housing and shaft to equal the drive shafts anyone tried that?

#14 miniSLO

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Posted 08 December 2008 - 10:00 PM

A far more sensible solution to the issue of torque steer would be to maximise your suspension settings in order to try to balance the problem particularly caster,good quality components with correct bushings and setup by a professional will decrease the torque steer issue to a comfortable level.


What angle you suggest for suspension settings (toe, castor, camber)
what you think about anti roll bar?




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