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Discussion Starter · #1 ·
Anyone know what the front/rear torque split of an EVO I is?

It feels like it's rear biased as I get the back end stepping out quite a lot in this winter weather. This is great when you want it, but it's taken me by surprise a couple of times lately. The last time the back end came around to meet the front, I was doing 70 mph and the car was doing what it wanted until I lifted off the throttle slightly http://www.ltregister.f9.co.uk/graphics/embarassed1.gif border|EQU| 0 align|EQU| absmiddle >!

Before every one replies saying you should not back off when this happens, I can assure you that keeping my right foot firmly planted was not helping matters in this case, only when I lifted off the back end tucked in again [img]http://www.ltregister.f9.co.uk/graphics/happy1.gif border|EQU| 0 align|EQU| absmiddle >. Anyone else had similar experiences?
 
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Discussion Starter · #2 ·
I think the Evo 1 inherited the 30:70 spilt of the Galant VR4 (source: that Evo 7 pdf!)

Rear-drive bias is something I've noticed too, certainly helps traction out of low speed corners
 
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Discussion Starter · #3 ·
I think it is 30:70 split biased towards the rear.
Like Chunky says you can feel the rear moving around more when you are pressing on.

If you were already breaking the rears traction then lifting off should have brought it back in line. Keep the foot planted if the power bias is to the front wheels (drag you out of the slide).

This of course doesn't apply if the car is above 80degrees to the angle of travel http://www.ltregister.f9.co.uk/graphics/Happy.gif border|EQU| 0 align|EQU| middle > yes, it will come back from there, but you've got to keep that throttle mashed and get the steering on the lock stops. Very quickly.
He he.
 
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Discussion Starter · #4 ·
Thanks guys,

70% rear - well that explains everything http://www.ltregister.f9.co.uk/graphics/biggrin1.gif border|EQU| 0 align|EQU| absmiddle >. I'm not sure how far the back end had broke out at the time - it let go big style to what felt like about 30 or 40 degrees but it's hard to tell - certainly got my attention.

I used to have an early GT4 (89 vintage) which was front biased - keeping your right foot planted always dragged you through. Nice car but didn't have anywhere near the same grunt of the Evo.

I've downloaded that pdf file - good info in it.

I'd better start wearing lighter shoes until summer comes [img]http://www.ltregister.f9.co.uk/graphics/wink1.gif border|EQU| 0 align|EQU| absmiddle >
 
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Discussion Starter · #5 ·
I thought I had read somewhere that there was a 48/52 percent split (font or rear biased I don't know), though to be fair I can't remember which version that was for.
Took my II for quite a quick blast round the lanes this weekend as the weather was nice. It behaved impeccibly (sp?), loading up in the corners then springing forwards. Nice. Still wary of sharp corners though after experiencing serious understeer earlier in the month but I'm wondering if that was mainly greasy roads now, or maybe my tyres just don't suit the wet so much. She seems perfect in the dry.

'Smilin' Jon
 
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Discussion Starter · #6 ·
I always assumed it was 50:50. On my Evo I GSR, if the roads are dry the back only comes out if you really try to force it. When it does come out I have recovered by lifting off but also by pressing which will send more power to the fron and make it front biased.
 
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Discussion Starter · #7 ·
Looking at the Evo VII pdf. I am now sure it is not the 30:70 system in the 92 Galant VR4. The Evo I has no electronic differentials. t si probably the same as in the Eclipse and and the 87 VR4.
 
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Discussion Starter · #8 ·
Must admit I'm totally confused now. In the EVO 7 pdf, it shows the 92 Gallant system as being electronically controlled 30:70 split. As it goes through the different EVO's, it states that the EVO I inherrited the Gallant system. It doesn't mention anything about the electronic system being dumped on the EVO II, but I read on this forum that someone has a viscous coupling spare from such a beast. My car certainly drives different to the GT4 I had but there is about 70 horses different which probably explains a lot.

I was interested to read within this thread that backing off helped other people but I think Wreckleford has hit the nail on the head. When my car let go, it was during WOT so I couldn't really use more throttle to pull it through. Apart from steering into the skid, lifting off was the only other 'change' available to me. To my relief (and surprise http://www.ltregister.f9.co.uk/graphics/biggrin1.gif border|EQU| 0 align|EQU| absmiddle >) it worked.

Thanks for the responses.
 
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Discussion Starter · #9 ·
Thinking about this, the 30/70 split doesn't seem right at all - despite what that .PDF says. I have driven my E1 in constant radius circles through the sidewindow (Imagine driving around a large roundabout in very wet conditions but getting a crick in your neck http://www.ltregister.f9.co.uk/graphics/Happy.gif border|EQU| 0 align|EQU| middle > ) And when I experimented and violently lifted off with full positive lock the back swung right out to about 120 degrees to the road (IE facing quarter backwards). After a few attempts I could recover from this by bouncing it off the limiter and sending all the power I could to the front wheels (which by now where on opposite lock and so were able to provide more grip than the rears and pull me out), If it had been 70% at the rear that would never have worked...This was all done in second gear.
Perhaps the .pdf refers to the works rally cars, as they must have had some changes otherwise they would have had centre diffs fail constantly when the handbrake was used on a stage.
 
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Discussion Starter · #10 ·
Just replaced the (worn out) viscous coupling on my Evo III with a new RALLIART uprated unit (thanks, Kevin at Coordsport). Graham at Quick Motorsport kindly showed me how the VC (Viscous Coupling) works using an old gearbox. I will try to explain, but you really need to see to understand!

The gearbox output goes direct drive to the front driveshafts. Additionally, it goes to the rear propshaft via a free differential (normal planet gears type). Now for the clever bit. The slip of this differential is controlled by the VC, as the input and output are extended to one side of the diff on cylindrical shafts, one inside the other. The VC fits over these shafts, and limits the slip between the shafts. From this description, I cannot see any torque split of over 50% to the rear wheels being possible.

Incidentally, you can replace the VC by removing the end plate of the gearbox, with the box in situ.

As Roger Clark said, Sideways, to Victory!
 
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Discussion Starter · #11 ·
I thought it was 50:50 spilt

the reason the rear end steps out is because the rear has a 60 % limited slip diff thats very high for a car
if you drive on a go kart it has no slip diff so its 100% go on the throttle and slide all the way thru the corners

but maybe i am wrong

a. de vries
 
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Discussion Starter · #12 ·
Hi,
I've had these boxes apart loads of times and it's impossible for these boxes to split any way other than 50/50 no matter what way ratios are arranged. The LSD's front and rear only limit torque to each wheel on the same axle.
Found this thread where it does a good job at explaining this theory. i know it's not an Evo but design is the same.
It reads:-


I know this is an old topic but I see that two of our prominent
members have cited news and commercial literature concerning the
validity of the uneven torque split in our cars. And in past posts I
too have stated that the torque is split unevenly as evidenced by
different front and rear differential ratios. Since then I have torn
a center differential/viscous coupling unit (CD/VCU) apart (thanks to
Frank Martin at Kormex) and come to a much different conclusion.
Torque is split evenly in all year TT and VR4s.

All torque enters the case of the CD/VCU through the ring gear on its
outside. All torque leaves the CD/VCU through the 2 output shafts.
Both output shafts must spin at the same rate if the VCU is operating
correctly (if the VCU is broken then the CD is an open diff and worse
all torque goes to the front wheels). If torque is split **unevely**
at the CD/VCU then each shaft **must** spin at a different rate. Both
shafts spin at the same rate so torque is split even, 50/50, front
and rear. The front diff reduction ratio is the same as the rear diff
times transfer case ratios so both shaft rotation rates are the same
coming out of CD/VCU.

More details and many pictures on our CD/VCU and the entire AWD
system can be found from the Tech Page at my web site.

It seems the myth of the 45/55 split started in the magazines
(probably based of front and rear diff ratios) as nowhere does
Mitsubishi state such a thing that I have seen. The DSM setup is
similar (but different gear arrangement in the CD) and the DSM Tech
manual clearly states a 50/50 split at the CD/VCU.

Now do we all agree that torque is split 50/50 in our cars or I have
a made a silly mistake in observation and mechanics somewhere?


Regards,
Paul.C
 
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