Centre Diff Control Use, the real translation!
27 October 2002, 10:19 PM
#33
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Shouldnt that be thanks JF! 
It saddens me that most people havent got a clue how to use the diff controller, the amount of traction you gain in the wet is phenominal. It makes the car much safer under braking too.
It saddens me that most people havent got a clue how to use the diff controller, the amount of traction you gain in the wet is phenominal. It makes the car much safer under braking too.
28 October 2002, 12:30 AM
#35
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The first time I used it (after reading Translated Handbook) the vibration noise was quite loud and that was just one click/light forward. That was good enough reason for me to not use it, maybe if I had another persons similar spec car to compare with I might of used it a bit more. I understand how it works but with a noise like I heard I wasnt taking any chances. Do others get this noise for just one green light forward ??
28 October 2002, 12:40 AM
#36
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you can if you are doing slow manouvers. When you are just moving the car around at low speed your going to get a slight shudder, once you start to drive it that will disapear. You get more shudder the more lock you put on, as the front diff is locking and transfering that lock load into the centre diff.
28 October 2002, 10:21 AM
#37
Thanks for that John. V Helpful 
Have just printed a copy off and put it in my owner manual for future owners. I think we all agree it would have been nice to have had this info when we bought our R/RA's.
Now, whats all this I hear about changing your gearing?
Have just printed a copy off and put it in my owner manual for future owners. I think we all agree it would have been nice to have had this info when we bought our R/RA's.
Now, whats all this I hear about changing your gearing?
30 October 2002, 01:48 PM
#39
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either, although if you are parking up, put it into diff open (the handbrake does this automatically anyway).
There are examples where you shouldnt adjust whilst moving, such as when the wheels are in the air or spinning. For example, you are stuck in a field with the wheels spinning. Stop what you are doing and select diff lock, then drive off, dont **** the diff lock in whilst spinning the back wheels in a mudpit.
There are examples where you shouldnt adjust whilst moving, such as when the wheels are in the air or spinning. For example, you are stuck in a field with the wheels spinning. Stop what you are doing and select diff lock, then drive off, dont **** the diff lock in whilst spinning the back wheels in a mudpit.
30 October 2002, 01:53 PM
#40
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I replaced my 5th gear ratio to a normal TypeR/RA 160MPH top rather than the V-Limited ratio that gave 180MPH. The ratio jump from 4th to 5th was just too big for my kind of driving.
30 October 2002, 01:55 PM
#41
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joh, surely the shudder is coming from the fact that the front and rear axles are moving at different speeds, meaning the centre diff needs to be freer that the setting is allwoing to account for the difference.
I cant see why in manouvering the front diff would be locking, it is a viscous lsd, which doesnt lock up so agressively as the rear plated diff.
Is it that the speed differential is greatest when manouvering as a fraction of the rpm of the wheels?
If this was the case, surely you would still feel that effect from the front when the diff is fully open.
and on another point, will fitting a front quaife potentially rectify this at all, since it is even less inclined to lock gthan the viscous diff? meanign I can manouver in greater values of lock.
And finally, is there a way of removing the notches from the dial, so we have a more easily continuously variable diff, or would this be pointless with my lame driving?
I cant see why in manouvering the front diff would be locking, it is a viscous lsd, which doesnt lock up so agressively as the rear plated diff.
Is it that the speed differential is greatest when manouvering as a fraction of the rpm of the wheels?
If this was the case, surely you would still feel that effect from the front when the diff is fully open.
and on another point, will fitting a front quaife potentially rectify this at all, since it is even less inclined to lock gthan the viscous diff? meanign I can manouver in greater values of lock.
And finally, is there a way of removing the notches from the dial, so we have a more easily continuously variable diff, or would this be pointless with my lame driving?
30 October 2002, 02:45 PM
#42
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The center diff works in a non-linear way, it is controlled by an electro magnet, at low speed (crawling) you can feel the diff pulsing when you have enough diff lock on. You will notice this more if you have different diameter tyres front rear, such as if the rears are worn more than the fronts. You should vary the diff setting to reflect your speed, (again, its only shudders when crawling or up to 15MPH normally when taking a hairpin), you set the diff to provide the torque split required for the speed and conditions. Of course when you are doing low speed maneuvers such as parking, you should wind the diff lock out so you are not shaking your teeth out. As the speed builds there is no shudder at all, even with fully locked diffs as the natural slip of the tyres/momentum takes care of it. The best advise I can give you is use your common sense and experiment with it, you will soon work out what is usable and what isn’t, it varies depending on conditions, speed and what you are doing.
Pretty sure my front diff is mechanical, not viscous. It looked like a mechanical diff to me when I had the box apart. I’ll check up on that tonight, I know mine has the later spec front LSD fitted to the Sti5 RA’s.
If you are doing low speed maneuvering, you should open the center diff. Don’t forget, the more lock you put on, the more the front diff binds up and therefore the more the center diff has to do. A fun experiment is to coast to a stop in a circle, winding more and more front bias in, the car stops like its got the brakes on because the steering lock, front diff bind up being fed into the center diff/rear diff massively increases the mechanical drag of the system.
I don’t see how fitting a front quaife would make any difference to be honest, but I wont discount it until its been tried. I don’t see the need to be honest as if you learn to drive the car properly you are not going to hit that problem anyway.
You have notches in your diff control dial? Mine doesn’t! With mine I have a click to take it out of fully open, its then totally free until you get to the other end of the scale and you get another click to put it into diff lock. From memory, all the TypeR/RA’s I have driven including 22B’s have it like this? Although it’s a while since I last drove a 22B and used the diff controller so maybe they changed this? That might go some way to explaining why they have 6 indicator lights on the dash, rather than a proper, analogue display.
I can’t comment on your driving Adam, never had the pleasure of witnessing it first hand. What I will say is make use of the center diff, in the wet in particular, you will be amazed at the traction you get compared to an open diff, it’s light-years ahead of a viscous center diff such as in the P1. The most startling difference is actually under heavy braking, you wouldn’t believe how much harder you can brake with the center diff wound up. This was the main reason why I wanted to help develop the programmable center diff controller, to improve braking performance. This is where most of the gains will come from for a road car I believe. And yes, 2 secs a mile is possible when using an active diff system in the forests.
As the speed builds there is no shudder at all, even with fully locked diffs as the natural slip of the tyres/momentum takes care of it. The best advise I can give you is use your common sense and experiment with it, you will soon work out what is usable and what isn’t, it varies depending on conditions, speed and what you are doing.Pretty sure my front diff is mechanical, not viscous. It looked like a mechanical diff to me when I had the box apart. I’ll check up on that tonight, I know mine has the later spec front LSD fitted to the Sti5 RA’s.
If you are doing low speed maneuvering, you should open the center diff. Don’t forget, the more lock you put on, the more the front diff binds up and therefore the more the center diff has to do. A fun experiment is to coast to a stop in a circle, winding more and more front bias in, the car stops like its got the brakes on because the steering lock, front diff bind up being fed into the center diff/rear diff massively increases the mechanical drag of the system.
I don’t see how fitting a front quaife would make any difference to be honest, but I wont discount it until its been tried. I don’t see the need to be honest as if you learn to drive the car properly you are not going to hit that problem anyway.
You have notches in your diff control dial? Mine doesn’t! With mine I have a click to take it out of fully open, its then totally free until you get to the other end of the scale and you get another click to put it into diff lock. From memory, all the TypeR/RA’s I have driven including 22B’s have it like this? Although it’s a while since I last drove a 22B and used the diff controller so maybe they changed this? That might go some way to explaining why they have 6 indicator lights on the dash, rather than a proper, analogue display.
I can’t comment on your driving Adam, never had the pleasure of witnessing it first hand. What I will say is make use of the center diff, in the wet in particular, you will be amazed at the traction you get compared to an open diff, it’s light-years ahead of a viscous center diff such as in the P1. The most startling difference is actually under heavy braking, you wouldn’t believe how much harder you can brake with the center diff wound up. This was the main reason why I wanted to help develop the programmable center diff controller, to improve braking performance. This is where most of the gains will come from for a road car I believe. And yes, 2 secs a mile is possible when using an active diff system in the forests.
30 October 2002, 03:20 PM
#43
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John, thanks for the explanation
perhaps you should have a word with pat, and develop the electronic diff between the two of you? I would love to be able to take advantage of the braking. with the six pots, I have a massive tendancy to lock up by stabbing at the brakes. Not driven it for a year so will have to appreciate this properly when I get it back and try again.
I changed the front diff more to cope with the power, than to change the handling. I assumed a viscous front diff, havent seen it myself, as I thought the only mechanical lsd which arent plate type are atbs. Tell me, how do non viscous, non atb, non plate type mechanical lsds work?
I only ask this, because i was certain they dont come with torsen diffs, else getting a quaife would be pointless. I know they dont exhibit the characteristics of a plated lsd up front, leaving only viscous as a mechanical option. This doesnt fit with the fact hat I had always been told front impreza diffs were either viscous coupled or open, centre diffs were viscous coupled or open with the variable lockup clutch, and rear diffs could be viscous coupled, plated (as in type r, ra and 22b) or open (as in sport aparently). in short, can you confirm that the front diff is plated?
I thought my 22b had 6 distinct positions between locked and unlocked, although the end positions were a much more significant stop. It is possible that I am completely wrong and it has just been too long since I messed around with it. either way it makes little difference.
[Edited by Adam M - 10/30/2002 3:52:06 PM]
perhaps you should have a word with pat, and develop the electronic diff between the two of you? I would love to be able to take advantage of the braking. with the six pots, I have a massive tendancy to lock up by stabbing at the brakes. Not driven it for a year so will have to appreciate this properly when I get it back and try again.
I changed the front diff more to cope with the power, than to change the handling. I assumed a viscous front diff, havent seen it myself, as I thought the only mechanical lsd which arent plate type are atbs. Tell me, how do non viscous, non atb, non plate type mechanical lsds work?
I only ask this, because i was certain they dont come with torsen diffs, else getting a quaife would be pointless. I know they dont exhibit the characteristics of a plated lsd up front, leaving only viscous as a mechanical option. This doesnt fit with the fact hat I had always been told front impreza diffs were either viscous coupled or open, centre diffs were viscous coupled or open with the variable lockup clutch, and rear diffs could be viscous coupled, plated (as in type r, ra and 22b) or open (as in sport aparently). in short, can you confirm that the front diff is plated?
I thought my 22b had 6 distinct positions between locked and unlocked, although the end positions were a much more significant stop. It is possible that I am completely wrong and it has just been too long since I messed around with it. either way it makes little difference.
[Edited by Adam M - 10/30/2002 3:52:06 PM]
31 October 2002, 11:43 AM
#45
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My Type R definately has six distinct clicks which correspond to the six lights on the dash. The fully open and locked positions are more distinctive as you say but there are definately some faint clicks in between too.
31 October 2002, 01:09 PM
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john,
can you not answer me?
spoken to pat, and he believes that the only front lsd to be supplied in the impreza is a viscous diff, yet you are sure your is not.
Is it possible you dont have a front lsd?
can you not answer me?
spoken to pat, and he believes that the only front lsd to be supplied in the impreza is a viscous diff, yet you are sure your is not.
Is it possible you dont have a front lsd?
31 October 2002, 01:47 PM
#49
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Pretty sure my front diff is mechanical, not viscous. It looked like a mechanical diff to me when I had the box apart. I’ll check up on that tonight, I know mine has the later spec front LSD fitted to the Sti5 RA’s.
And yes, i am 100% certain i have a front LSD because i was stairing it in the face 2 weeks ago when i had my box in 50 pieces. There are lots of diferent versions of the Front LSD used on the typeRA.
31 October 2002, 02:50 PM
#50
How easy was it to take the box off john?
Im the opposite to you as I would like a higher 5th? or, an overall increase in gearing to the standard STI 22/1000 gear set.
I sometimes get required to drive on the motorway and the oil starts getting hot if you go over 4000rpm for too long.
Im the opposite to you as I would like a higher 5th? or, an overall increase in gearing to the standard STI 22/1000 gear set.
I sometimes get required to drive on the motorway and the oil starts getting hot if you go over 4000rpm for too long.
31 October 2002, 02:54 PM
#51
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I didnt do the job, i couldnt be bothered with the agro or strugling under the car so Prosport in manchester did the work for me. I needed a couple of syncros changing anyway so it made sense to swap the 5th at the same time.
My 5th gear is perfect, do you want to buy it and save some money over buying new?
My 5th gear is perfect, do you want to buy it and save some money over buying new?
31 October 2002, 05:48 PM
#52
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whhhhhhhhoooooooaaaaaa there.
john, was only playing with the arent you going to answer my question line.
No need to get all FFSakey on me.
just thought since you had answered something else, you had had time to answer but didnt, maybe cos you hate me, I dont know!
john, was only playing with the arent you going to answer my question line.
No need to get all FFSakey on me.
just thought since you had answered something else, you had had time to answer but didnt, maybe cos you hate me, I dont know!
10 January 2003, 03:50 PM
#54
Didn't see this thread before. NICE ONE JOHN!!!!
REALLY pleased to hear that the diff doesn't get damaged by the nasty clunky sounds, etc.
Also, really surprised to hear that the diff opens fully when pulling the handbrake as (GOD KNOWS how) I've never noticed this when driving - but saying that I always wind the diff fully open before pulling the handbrake anyway.
Adam
All 22Bs I've driven (in-fact, all DCCD scoobs I've driven) have a smooth transition between the different lights.
--
the auto diff thing is a dodgy one IMHO.
Locking the diff up will only help dead straight line braking on really good surfaces. Locking it completely and then trying to turn will cause all sorts of nasty side-effects. When you then bare in mind that the car can turn without steering input, you need all sorts of innertia packs, etc to let a very clever computer know exactly what's happening to the car before it can make a decision on what to do with the diffs.
All the best
Simon
REALLY pleased to hear that the diff doesn't get damaged by the nasty clunky sounds, etc.
Also, really surprised to hear that the diff opens fully when pulling the handbrake as (GOD KNOWS how) I've never noticed this when driving - but saying that I always wind the diff fully open before pulling the handbrake anyway.
Adam
All 22Bs I've driven (in-fact, all DCCD scoobs I've driven) have a smooth transition between the different lights.
--
the auto diff thing is a dodgy one IMHO.
Locking the diff up will only help dead straight line braking on really good surfaces. Locking it completely and then trying to turn will cause all sorts of nasty side-effects. When you then bare in mind that the car can turn without steering input, you need all sorts of innertia packs, etc to let a very clever computer know exactly what's happening to the car before it can make a decision on what to do with the diffs.
All the best
Simon
10 January 2003, 04:08 PM
#57
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Easiest way to feel the diff release simon, is to put it in diff lock at a slow speed and start a slow turn. You will feel it binding up. Now just lift the handbrake untill the dash warning light iluminates and you will feel it free up and go to diff open. The dash light stays in its set position. Great or what?
The Auto DCCD, if it uses a similar control stategy as the automatic gearbox, auto torque proportioning system used on the legacy, then it will have a steering wheel position potentiometer.
Simon and I spoke about a genuinely active system a while back and its incredibly complex when you start to analyze handling transitions. You need expensive G sensor packs to do it a proper job. I am really interested in how the DCCD-A works, because i dont know at the moment what inputs it uses.
The Auto DCCD, if it uses a similar control stategy as the automatic gearbox, auto torque proportioning system used on the legacy, then it will have a steering wheel position potentiometer.
Simon and I spoke about a genuinely active system a while back and its incredibly complex when you start to analyze handling transitions. You need expensive G sensor packs to do it a proper job. I am really interested in how the DCCD-A works, because i dont know at the moment what inputs it uses.
10 January 2003, 04:13 PM
#58
does anyone have a link to any info about the DCCD-A as it may well use the full blown technology we spoke about, in which case it will be very interesting, especially if it is user adjustable / mappable.
cheers
Simon
PS. I'll send a quick email to see if it's what I think it is
cheers
Simon
PS. I'll send a quick email to see if it's what I think it is
10 January 2003, 06:41 PM
#59
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I never really tried fooling around with my dif settings because of the clunking sound at low speeds. Does anyone know in general what setting to use in what situation. Example, on a track day, how much lock should you dial in. On the wet etc...
I know it depends on a lot of factors but in general?
I know it depends on a lot of factors but in general?
12 January 2003, 02:27 PM
#60
OK
It doesn't SOUND like the DCCD-A *is* the thing I was thinking it was.
Prodrive are working on a fabulous new computerised diff set-up called ATD (I think it stands for something like Automatic Torque Distribution) whic is only just becoming non-top-secret and it seems I am now able to talk about it.
The amount of development and testing that has gone in to the system is incredible and the results are staggering.
The basic deal is that there are innertia packs in the car and almost every major moving part of the car is monitored. This includes all of the driving controls.
So they are able to make the car do exactly what the driver wanted it to do without the driver having any idea how to do it! LOL.
eg. For a given driver input (eg: wheel 15 degrees right, throttle 25%, etc, etc) they have a map which says what the driver wants the car to do. If the car isn't doing exactly that (which they can tell by monitoring the innertia packs) they alter the diffs to make it do that.
The most amazing part of this system is that you can fit all sorts of different tyres on the car and it doesn't affect the overall handling as the diffs just make the car do what it was supposed to and take car of all the tricky little adjustments, etc.
I haven't driven the system for a while now and there are many improvements it seems, so I'll be driving it this week and will report back
all the best
Simon
It doesn't SOUND like the DCCD-A *is* the thing I was thinking it was.
Prodrive are working on a fabulous new computerised diff set-up called ATD (I think it stands for something like Automatic Torque Distribution) whic is only just becoming non-top-secret and it seems I am now able to talk about it.
The amount of development and testing that has gone in to the system is incredible and the results are staggering.
The basic deal is that there are innertia packs in the car and almost every major moving part of the car is monitored. This includes all of the driving controls.
So they are able to make the car do exactly what the driver wanted it to do without the driver having any idea how to do it! LOL.
eg. For a given driver input (eg: wheel 15 degrees right, throttle 25%, etc, etc) they have a map which says what the driver wants the car to do. If the car isn't doing exactly that (which they can tell by monitoring the innertia packs) they alter the diffs to make it do that.
The most amazing part of this system is that you can fit all sorts of different tyres on the car and it doesn't affect the overall handling as the diffs just make the car do what it was supposed to and take car of all the tricky little adjustments, etc.
I haven't driven the system for a while now and there are many improvements it seems, so I'll be driving it this week and will report back
all the best
Simon