I have a quick but important question - anyone with a Type R should be able to help. I picked up my new (to me) STI Type R ver 3 from the garage on Saturday and had a large crash on Sunday. I was told by the garage that the `safe' position to have the centre diff control was in the `back' position - the bottom light on the dashboard display. Was this correct?

I suspect they told me right and I just made a mistake at the wrong moment - lightly pressing the throttle before I finished a turn and ending up straddling a ditch looking at my new buckled aluminium bonnet. If they told me wrong, however, and I had the setting at 80% power through the rear wheels I'll be even less happy with life. Help!

Denn,

The normal position for the diff control is on the bottom i.e. 1st green indicator. This gives a static power split of 65% rear, 35% front. Moving the diff control forward progressively limits the slip of the centre diff to the point where it is completely locked on a 50/50 power split.

Compared to a UK car the Type R has a rear wheel handling bias, complicated by the fact that if slip is detected at the back, power is sent to the front. This makes the car predictable and controllable when on the power, but if you let off the throttle and just steer into the slide the power transfers to the front and so the car tries to turn in the direction of the front wheels, then the back end bites suddenly and your car becomes very unstable to say the least, and often results oin very dramatic fishtailing or worse.

Hope that makes sense.

Chris.

Thanks for that Chris - it's all starting to make sense! I'm pretty sure when I turned into the slide I applied the power but it had snapped out quite aggresively and launched off the road within a second or so, not leaving me much opportunity!

It goes without saying that I'm totally gutted - if the car's a right off I'm gonna stick with a `standard' STI, unless someone wants to volunteer some car-specific training ..... http://bbs.scoobynet.co.uk/wink.gif

DENN CITY

pressed wrong key there !!!!!

Where is the diff control located, and what does it look like. Not all type R's have them (I think)?

The above description of the diff lock is not correct! AFAIK, and independant tests have borne this out, the centre diff is fully open when on the bottom green square. What this means is that in a slip situation at the rear _all_ of your power goes there.

For instance, if the rear wheels are on sheet ice and the front wheels are not the rear wheels will spin and the car will remain stationary when the diff lock is down (bottom green).

Rgds,

M

Hmmmm - I'm trying to understand but there seems to be a bit of difference of opinion here.

Airhead - the diff control was/is located between the front seats and looks like a small slider control. Quite innocuous looking item, really. I think only the version 3 Type R's and newer had them. Anyone?

I crashed my 22B the second time I drove it and blamed the Diff - not necesserily the case I lost it ,froze and lifted off oops!
I subsequently spent a day with Mike at Performance Drivers learning about limit handling and the diff on a wet airfield. Very illuminating, the upshot was leave it at the back and DON'T play with it unless you are a good driver and it is dry.
Email Mike at PD and I'm sure that he can explain the dynamics to you.
Regards
Geoff

Denn ,
Im sorry to hear of your accident, i own and drive a type r and personally dont really mess with the diff too much ,im sure i wouldnt cause you to crash though that is always down to driver error, no personal offense to yourself. i am going to do an air field day soon and then play about with it a bit more , you just cant do these things on a public road or even a track day co that that many cars about.

DavidRB

Nice one!

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>DON'T play with it unless you are a good driver and it is dry.<HR></BLOCKQUOTE>

No wrong... DO NOT wind it forward on dry roads. You'll knacker the diff in no time.

Also wind it fully back when manuovring at low speed eg car park.. If not you'll hear the diffs complain...

I use mine as follows

Full back.. Dry roads
one notch forward. Wet roads ( Note Wet not damp)
2 notches FWD for very wet (ie standing water or lottsa leaves etc)

Fully forward on Snow, mud etc..

The idea being to get some of the power out of the rear as conditions get worse

Simon.. My info also points to 65/35 rear biased split when fully open.


Richard

Simon,

Are you saying then when then diff is fully open (i.e. r 65% f35%) and slip is detected at the rear, that all the power then goes to the rear ? I thought that this was a limited slip device where the diff control efectively allows more or less slip depending on the setting but with power always going to the fron

If, when slip was detected at the rear, all power was transferred there, the front wheels would never have an active effect on pulling the car out of the resultant slide with the power on. It would as a result, lose all the advantages of being 4 wheel drive.

This is why I made my comments. You come out of a corner with too much power and the diff open, the back end spins and slides out but 35% drive still goes to the front. You then let off the power and the back end instantly grips. Then due to drive going to the front the car pulls in the direction of the steering, feeding more energy to the rear due to weight transfer, thereby causing the back end to fish tail violently. This is why you don't let off, but moderate the power to balance the car and allow the wheels to find traction and drag you out of the slide.

Chris.

I didn't know the scooby had Super Hicas Control units which can send the power to the front wheels if slipping? I don't think so.

Slip is not detected by anything from what I can see, it like driving a normal Scooby when you get it sidewayds, once its gone its gone, not transferring the power to front and back electronically.

Harj... who drives a 22B with Full Lock on all the time http://bbs.scoobynet.co.uk/tongue.gif LOL

[This message has been edited by harj (edited 07 February 2001).]

Denn

Unfortunately you are not the first and certainly won't be the last to be caught out by the Type R's handling.

Understeer on the way in, oversteer on the way out.

What does not help, on tarmac, is that Subaru diff are ROTATION sensing, not torque sensing. This means they don't really do much until a wheel starts spinning. If you are new to the car... and its all happening very quickly, this won't help you.

The Type R has this torque split and centre diff, for homologation reasons. Its of no use on the road (the 40/60 of the 4 door is much better, the 50/50 of the new WRX is brilliant).

Don't be frightened of the car (hope it can be repaired OK), but do get yourself on either a RWD Rally School course, Wetter the Better or Mike Peck's excellent Performance Driving course.

Denn

when you get back on the road take your time and get used to all that lovley power a bit at a time i have a STi type RA 4 dr and used to have a 2 dr both with the famous diff and i have to say the 4 dr does let you know a bit sooner if its going to go but when they go they go big but with time and some professional tuition you will be able to fully exploit your type R which are fantastic cars. http://bbs.scoobynet.co.uk/biggrin.gif
so unless you really know what youre doing wind it back and put some sellotape over it.

Enjoy

Tim

Hmmmm this is interesting...

Does this mean that if the car has one wheel off the ground, the car will go nowhere because all the power will go to the one wheel?

If so, should you lock the diff up (to stop the power transfer) so you still get power to the wheels (or axle) on the ground?

Reason I ask is that I stopped in a layby in a country lane once and couldn't get the car to move because one wheel was off the ground. Didn't matter what I did with the diff. Only way I got moving was to reverse a bit to get all the wheels on the ground and take a run up...

Rich
65/35 : Thanks mate. Shows what I know! http://bbs.scoobynet.co.uk/biggrin.gif

Chris
Hi Mate
"If, when slip was detected at the rear, all power was transferred there, the front wheels would never have an active effect on pulling the car out of the resultant slide with the power on. It would as a result, lose all the advantages of being 4 wheel drive."

That's correct (to a degree), and is exactly what happens. With the diff set fully open, you are effectively in a RWD car (although a very wierd one, as some toqrue goes to the front until the rear light up then VERY VERY little is left there). In a slide you are faced with a huge challenge....

More gas will keep the car sideways (stopping it from snapping back) by keeping the rears spinning. A little bit of gas will keep a bit of power going to the fronts (helping you to drag the nose back straight again. But too much gas will lock up the rear diff creating all sorts of havoc if you're not on the ball (and highly skilled).

"You come out of a corner with too much power and the diff open, the back end spins and slides out but 35% drive still goes to the front. You then let off the power and the back end instantly grips. Then due to drive going to the front the car pulls in the direction of the steering, feeding more energy to the rear due to weight transfer, thereby causing the back end to fish tail violently. This is why you don't let off, but moderate the power to balance the car and allow the wheels to find traction and drag you out of the slide."

I think you are confusing a few different things mate.

The backend slides out due to the amount of power going to the rear (as the diff is open and has allowed the transfer of power to the rears (which have just started to lose traction)). If you come off the power the rears may dig in (as you say) but the fishtail / pendulum effect is not caused by drive at the front, it is merely the built up energy in the car / suspension and the direction of the front wheels that causes it. In fact, any drive to the front would (at this point) *reduce* this effect (not much mind you!) as engine braking would slow the front end down a bit (a more advanced state of lift-off-oversteer).

to be honest, I am altering the diff setting at least every couple of minutes if the road conditions are changeable as it makes a dramatic effect on the limit handling characteristic of the car. I would genuinely not feel safe driving it on wet roads in the fully open position unless I was driving REALLY REALLY slow.

cheers

Simon

Harj,

I've looked at my post again but can't see any mention of super hicas anything.

The diff is a limited slip device which at fully open allows 65% of the power to go to the rear wheels. When slip starts at the rear the front wheels are still being driven, or am I wrong ?

When slip occurs does the car just revert to being a rear wheel drive car. It seems to bit odd that a 4 wheel drive car should revert to rear wheel drive just when you need power to the front wheels http://bbs.scoobynet.co.uk/rolleyes.gif

I may not be explaining it very well but if you look on the

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by Richard F:
<B>&lt;snip&gt;
Reason I ask is that I stopped in a layby in a country lane once and couldn't get the car to move because one wheel was off the ground. Didn't matter what I did with the diff. Only way I got moving was to reverse a bit to get all the wheels on the ground and take a run up...[/quote]

The diff control only affects the centre diff, you must have been in a situation where shifting torque between the front & rear wheels didn't help. What you need is a way of transferring torque from one side of an axle to the other.

Getting one stationary and one spinning wheel on the same axle can happen on an open diff, like the front diff. I've had it happen with one wheel on mud (in an FWD car). The problem is that all the torque goes to the wheel with the least resistance (or the one spinning faster).

The solution is to lock the diff "manually". Stick the car in gear, press the throttle, come of the clutch and get the one wheel spinning. <I>Then</I> with your left foot, press the brake pedal! This acts like a crude limited slip diff, locking the two wheels together. Torque will go back to the wheel with grip and hopefully, the car will start to move.

cwal1

Are you sure? I would say quite the oposite.

With the diff in the fully open position (full back) power will be channel to the direction of least resistance, and this usually ends up being the rear as most of the torque is going there. I also thought it was a higher split than 65/35. It feels more like 70/30 - 75/25, but I could be wrong.

The added complication in terms of limit handling in a Type R is the aggressive nature of the *rear* diff. If you light up the rears, the rear diff can lock completely meaning you have a VERY aggressive powerslide on your hands if you're not in-control AND ready for it.

This is great for traction out of slow bends and making the car more adjustable whilst still providing lots of traction from the fronts, but can be a right handful on a wet road.

I always wind the diff forward a notch or two if the roads are slippy, but this is not necessarily the best thing to do.

best regards

Simon

Thanks again everyone. Basically, this little switch has quite an effect on the car's handling. I had an RAC report done on the car and it specifically mentioned getting operating instructions for the centre diff but I didn't pay it much attention!

If the car is repairable I'm definitely investing in a driving course or two - an empty car park and the money for new tyres also might be a good idea http://bbs.scoobynet.co.uk/smile.gif

cwal1

Hi mate...
re: seems silly it reverting to rwd and losing benefits of awd.. I know mate.. but. This diff was only put on the car for homologation purposes for rallying. RWD cars generally exhibit *better* (I hate that word) handling tham AWD on dry tarmac and many other circumstances. Traction is not always the issue.

Re: drive is still at the front wheels. I believe this is true, although not very much. It feels as though you can get rid of all the torque out the rear wheels if you spin them enough.

re: Driving Techniques. It seems that I failed when I wrote that article to articulate exactly what I meant. Could you let me know which part you are refering to or just roughly how you feel it differs from what I'm saying? Bare in mind also that the article in question is written for a normal AWD car, not a type R.

This is all good stuff as we all learn from it.

best regards

Simon

Simon,

I don't think have failed - I think it is me who is failing to get over my point. The driving techniques section I described seems to describe pretty accurately what you feel in the car when you lift off the power in order to catch a power slide. I added the bit about weight transfer aggravating the slide and causing fishtailing because that's how my car seems to behave in those circumstances.

Chris.

Active control unit - medicine for all of these problems.
 

Im using active control unit for central differential. It is programmable unit (via RS232 port) - (speed and turbo pressure sensitive) with hadbrake and leftfoot braking override. (+ 2 additional inputs). Group N rally cars uses the same unit. MY friend developed it over three years. Now the tarmac and gravel settings (maps) are completed. Snow maps waiting for me :-)

Denn City: Are you willing to sell your damaged type R? Im interested.

Dan

I think there's a chance he'll have repaired it or sold it some time in the last three and a half years! ;)

Whats all this 65% 35% ??

My sti manual says its 64% 36% ;)

I lost a sti5typeR the first day I had it around a local roundabout. Over corrected and somehow managed to keep it on the road after a bit of fishtailing!

Never really got to grips with the manual diff, and on country roads was difficult to stay with normal uk turbos. Chopped in for a P1 and never looked back.