Centre Diff Control Use, the real translation!
10 February 2003, 12:28 AM
#63
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no, the centre diff controller takes it's input from the handbrake warning light switch. If you make sure that still operates and the light on the dash comes on, it will work fine.
11 February 2003, 10:28 AM
#65
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John,
getting back to the road controlness of it.
Is there no way you could formulate a "map" in your head of exactly how you use it that we could then program ourselves into our own dccd-a?
from what you are saying it seems to be merely degree of lock is proportional to speed, I would have thought it would be more complex than that.
I would like to see 50% to max lock under braking too, although I am not sure if this would be a good thing.
the rear are more inclined to lock as they have much less loading. by locking the diff, the front brakes have the ability to lock the rear wheels too. Therefore are the rear wheels going to make it more difficult to lock the fronts (good thing!) or are the front brakes (6 pots in my case) going to have no difficulty in locking the rears and potentially inducing a four wheel lockup which must be a very bad thing.
John,
I know you discounted the system that was being planned for whatever reason, but knwoing what you see as its flaws, do you not think you could have a bettr go at it yourself? I would be more than willing to attempt to put it into practice, I am just short of the map required to do this.
I am also positive that the dccd a uses the same running diff as our cars, the only difference is the auto control instead of the manual. this means we could possibly butcher theirs when it goes into production, and have a look at what sesnory inputs it uses.
thoughts?
getting back to the road controlness of it.
Is there no way you could formulate a "map" in your head of exactly how you use it that we could then program ourselves into our own dccd-a?
from what you are saying it seems to be merely degree of lock is proportional to speed, I would have thought it would be more complex than that.
I would like to see 50% to max lock under braking too, although I am not sure if this would be a good thing.
the rear are more inclined to lock as they have much less loading. by locking the diff, the front brakes have the ability to lock the rear wheels too. Therefore are the rear wheels going to make it more difficult to lock the fronts (good thing!) or are the front brakes (6 pots in my case) going to have no difficulty in locking the rears and potentially inducing a four wheel lockup which must be a very bad thing.
John,
I know you discounted the system that was being planned for whatever reason, but knwoing what you see as its flaws, do you not think you could have a bettr go at it yourself? I would be more than willing to attempt to put it into practice, I am just short of the map required to do this.
I am also positive that the dccd a uses the same running diff as our cars, the only difference is the auto control instead of the manual. this means we could possibly butcher theirs when it goes into production, and have a look at what sesnory inputs it uses.
thoughts?
12 February 2003, 03:44 PM
#66
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Are you asking me to write a user guide based on when, where and why I set the diff settings? If you mean can you write a map for use in a controller, then yes you can. The reality of it is you need different maps for the type of driving you are doing, be it road, track or loose surface. You also need different maps depending on weather conditions.
I am not saying the diff lock is speed dependant only, I think you misunderstood (or I didn’t explain well) what I was saying about taking care of the effect of juddering at low speed. All I meant by that was when you get to very low speed you must wind the diff lock out, irrespective of the type of conditions/driving you are doing just prior to you coming to do your parking maneuvers. In very tight chicanes when using the diff lock set high under hard driving you will always get a certain amount of shock loading, but when you are just doing your parking up, going to MacDonald’s etc you should wind the diff to open.
To do an active controller properly, you need sensor packs integrated into the active controller that measure G in all directions. You also need a steering wheel position sensor and speed sensors for all four wheels. You then need to add in boost, throttle position, brake pressure, handbrake activation, and speed into the equation.
Applying extra center diff lock under braking may be the right thing to do for straight-line stability under braking, allowing extra retardation due to load sharing between all four corners. That may be disastrous if you want to trail brake into a corner, as it will induce understeer, so the logic in the center diff map has to be very sophisticated.
You also need to vary the % LSD applied depending on speed and the type of surface. For example in medium speed tight corner exits I would want more front traction that in a corner that is more open and higher speed. In the dry I would want the diff lock increasing under heavy acceleration from low speed and as the speed increases the lock ratio backing off, however if the car were to get into a high speed half spin I would want the center diff lock to increase so I could slam the power in and use the front to drag it our of the spin.
I didn’t discount the system on a technical basis at all; it is good value for money, especially for guys competing in special stage rallies. I think it’s less suited to track/road driving, but it still has a lot of merits. It needed developing a fair bit when I saw it, but that was obvious based on the fact it was brand new. I chose not to use it for personal reasons.
As I understand it, the center diff used in the DCCD-A on the USDM/JDM STi is a different physical diff unit to that used in our cars. I am trying to get some confirmation on this as nothing is in the public domain right now. If it is the same unit then I see no reason why we couldn’t adopt it on our cars. The question for me would be is it worth it? Will it do what I want? Until I drive a USDM STi or DCCD-A equipped STi8 TypeRA Spec C I wont know.
I am not saying the diff lock is speed dependant only, I think you misunderstood (or I didn’t explain well) what I was saying about taking care of the effect of juddering at low speed. All I meant by that was when you get to very low speed you must wind the diff lock out, irrespective of the type of conditions/driving you are doing just prior to you coming to do your parking maneuvers. In very tight chicanes when using the diff lock set high under hard driving you will always get a certain amount of shock loading, but when you are just doing your parking up, going to MacDonald’s etc you should wind the diff to open.
To do an active controller properly, you need sensor packs integrated into the active controller that measure G in all directions. You also need a steering wheel position sensor and speed sensors for all four wheels. You then need to add in boost, throttle position, brake pressure, handbrake activation, and speed into the equation.
Applying extra center diff lock under braking may be the right thing to do for straight-line stability under braking, allowing extra retardation due to load sharing between all four corners. That may be disastrous if you want to trail brake into a corner, as it will induce understeer, so the logic in the center diff map has to be very sophisticated.
You also need to vary the % LSD applied depending on speed and the type of surface. For example in medium speed tight corner exits I would want more front traction that in a corner that is more open and higher speed. In the dry I would want the diff lock increasing under heavy acceleration from low speed and as the speed increases the lock ratio backing off, however if the car were to get into a high speed half spin I would want the center diff lock to increase so I could slam the power in and use the front to drag it our of the spin.
I didn’t discount the system on a technical basis at all; it is good value for money, especially for guys competing in special stage rallies. I think it’s less suited to track/road driving, but it still has a lot of merits. It needed developing a fair bit when I saw it, but that was obvious based on the fact it was brand new. I chose not to use it for personal reasons.
As I understand it, the center diff used in the DCCD-A on the USDM/JDM STi is a different physical diff unit to that used in our cars. I am trying to get some confirmation on this as nothing is in the public domain right now. If it is the same unit then I see no reason why we couldn’t adopt it on our cars. The question for me would be is it worth it? Will it do what I want? Until I drive a USDM STi or DCCD-A equipped STi8 TypeRA Spec C I wont know.
12 February 2003, 03:54 PM
#67
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I think it was I who misinterpreted what you had said.
Fairly comprehensive now though.
thanks for the explanation.
it comes down to the fact that if you udnerstand exactly what yu want from the diff and when you want it then someone like you will be far better off with a manual controller than an adapted auto one.
Unfortunately I dont have your driving skill so would have liked an auto system to kind of do the work for me. At the moment I am inclined to think that I should forget electronics and learn to really drive, then one day I might be a position to become my own automatic controller.
I think retro fit of the dccda will be a nightmare, as I am certain it will have inputs that our cars simply dont like wheel speed sensors, which I believe tobe missing from ou non abs equipped vehicles.
a real shame, but never mind.
incidentally, I had no idea why you didnt go for the townend gizmo. I discounted because it didnt have an analogue brake pedal sensor, nor steering angle sensor. Got the impression it ran from throttle position only and not boost.
Overall, I am going to go with the driving lessons first and foremost, I am just afraid that with so much torque the car might be beyond my driving capacility and one day may catch me out in a rather expensive way!
Fairly comprehensive now though.
thanks for the explanation.
it comes down to the fact that if you udnerstand exactly what yu want from the diff and when you want it then someone like you will be far better off with a manual controller than an adapted auto one.
Unfortunately I dont have your driving skill so would have liked an auto system to kind of do the work for me. At the moment I am inclined to think that I should forget electronics and learn to really drive, then one day I might be a position to become my own automatic controller.
I think retro fit of the dccda will be a nightmare, as I am certain it will have inputs that our cars simply dont like wheel speed sensors, which I believe tobe missing from ou non abs equipped vehicles.
a real shame, but never mind.
incidentally, I had no idea why you didnt go for the townend gizmo. I discounted because it didnt have an analogue brake pedal sensor, nor steering angle sensor. Got the impression it ran from throttle position only and not boost.
Overall, I am going to go with the driving lessons first and foremost, I am just afraid that with so much torque the car might be beyond my driving capacility and one day may catch me out in a rather expensive way!
12 February 2003, 05:45 PM
#68
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it didnt have boost presure sensing when i looked at it.
Glad you see the use of the DCCD a bit clearer now.
Dont forget Adam, at the end of the day it's all down to how you use those feet and hands. Just because you have a monster power engine doesnt mean you cant easily control that using what you were born with. What you will have to do is re-educate yourself in what those dangly bits can do for you.
Going OT i know, but using my Westie as an example. At Oulton Park there is a straight between druids and old hall. In most cars it's just foot to the floor wet or dry all the way down that straight. In the westie i used to have to look for a slight crest mid straight and be ready to ease the throttle out then back in as the rear tyres would start spinning as i went over the crest. This was at 130MPH, huge fun to be able to light the tyres up at those speeds and then play with how leary you want to be.
If you train yourself to expect to have to modulate the throttle more and accept that just driving full throttle irespective of the road isnt possible any more, nothing is a surprise and you can exploit what you have. The days of floor it and steer should be over for you, and that is a good thing because it allows you to make the car dance, rather than just go. If you dont want to have to think so intensly, dont use full throttle, easy peasy.
Glad you see the use of the DCCD a bit clearer now.
Dont forget Adam, at the end of the day it's all down to how you use those feet and hands. Just because you have a monster power engine doesnt mean you cant easily control that using what you were born with. What you will have to do is re-educate yourself in what those dangly bits can do for you.
Going OT i know, but using my Westie as an example. At Oulton Park there is a straight between druids and old hall. In most cars it's just foot to the floor wet or dry all the way down that straight. In the westie i used to have to look for a slight crest mid straight and be ready to ease the throttle out then back in as the rear tyres would start spinning as i went over the crest. This was at 130MPH, huge fun to be able to light the tyres up at those speeds and then play with how leary you want to be.
If you train yourself to expect to have to modulate the throttle more and accept that just driving full throttle irespective of the road isnt possible any more, nothing is a surprise and you can exploit what you have. The days of floor it and steer should be over for you, and that is a good thing because it allows you to make the car dance, rather than just go. If you dont want to have to think so intensly, dont use full throttle, easy peasy.
12 February 2003, 06:22 PM
#69
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I would highly recommend a few weeks riding around on a modern 1000+cc superbike to hone the fine art of throttle and brake modulation 
PS >>>>> In the rain
PS >>>>> In the rain
12 February 2003, 06:36 PM
#71
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Are these diffs 'EVER' available secondhand ? I have been looking for some time now and have never come across one 
I presume the DCCD and extension housing are a direct swap with the viscous unit ?
13 February 2003, 01:34 AM
#74
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no, adams is a japanese spec car, or rather was.
All the 22B's including the 16 TypeUK have the DCCD centre diff and plated rear diff, they just changed the final drive ratio.
All the 22B's including the 16 TypeUK have the DCCD centre diff and plated rear diff, they just changed the final drive ratio.
13 February 2003, 03:46 AM
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it would intersting to know if in the UK 22b's the rear diff was changed from the R180 to the R160, or just the ratio ..... if that is the case, were can one get at 3.9 for a R180 ?
13 February 2003, 06:49 AM
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Well, DCCD-A uses the ABS sensors as an input, so retro-fitting an older car is gonna be tough...
DCCD-A AWD controller sensors/inputs: wheel speed sensors, G sensor, throttle sensor, ABS controller, brake switch, handbrake switch, and mode switch/manual dial.
DCCD-A AWD controller sensors/inputs: wheel speed sensors, G sensor, throttle sensor, ABS controller, brake switch, handbrake switch, and mode switch/manual dial.
13 February 2003, 08:56 AM
#77
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my car was and is a jap.
the final drive is now 3.9 which is common to neither 22B since the jap was 4.44 and the UK was 4.11.
The UK 22B still has an R180 but crown wheel and pinions for R180s in anything other than 4.11 are an absolute pig to find, and if I strip thse, the likelihood is I will have to revert to 4.44 which might be a touch manic!
The centre diff does just bolt on, but even if you can get hold of one (rare but possible) you need the diff controller, and these arent quite so common.
If you need help with such things, then the best people to speak to on this are moray mackenzie and pat.
the final drive is now 3.9 which is common to neither 22B since the jap was 4.44 and the UK was 4.11.
The UK 22B still has an R180 but crown wheel and pinions for R180s in anything other than 4.11 are an absolute pig to find, and if I strip thse, the likelihood is I will have to revert to 4.44 which might be a touch manic!
The centre diff does just bolt on, but even if you can get hold of one (rare but possible) you need the diff controller, and these arent quite so common.
If you need help with such things, then the best people to speak to on this are moray mackenzie and pat.
13 February 2003, 11:20 AM
#78
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I have a brand new STI gearbox for a classic for sale with:-
4.444:1 Crown wheel
Type R/RA ratio set
electric DCCD centre diff
All new casings, diffs, gears, everything brand spanking...
All built up and ready to go.
Any takers?
4.444:1 Crown wheel
Type R/RA ratio set
electric DCCD centre diff
All new casings, diffs, gears, everything brand spanking...
All built up and ready to go.
Any takers?
20 July 2003, 11:14 PM
#80
Scooby Senior
Hey john can you please tell me Prosports phone numebr as I am in Newcastle with a Black Diamond Cluth that needs replacing after 2000 miles of non aggressive driving. And also fourth gear is becoming crunchy on down shifts and first jumps out when accelerating and then coming off the power.
21 July 2003, 12:39 AM
#84
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Thanks mate will phone them tomorrow is there anyone in particular you spoke to that knows there stuff and what price you want for the 5th gear you got and what difference does it make
21 July 2003, 12:48 AM
#85
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Give them a call, if the guys who do the box builds are busy they will call you back with the info you need later. It's a proper Subaru specialist so dont worry about talking to the right person.
My spare 5th is the same ratio as a non TypeR/RA STi 5th, so its slightly higher giving 22MPH/1000rpm to the normal RA 19MPH/1000rpm. The Limited edition STi5's have this higher 5th. Some people prefer it if they are doing a lot of motorway miles, i prefered the lower RA 5th so swapped it over. Pricewise, i would have to look it up, probably cost you 1/2 what the new cost is.
My spare 5th is the same ratio as a non TypeR/RA STi 5th, so its slightly higher giving 22MPH/1000rpm to the normal RA 19MPH/1000rpm. The Limited edition STi5's have this higher 5th. Some people prefer it if they are doing a lot of motorway miles, i prefered the lower RA 5th so swapped it over. Pricewise, i would have to look it up, probably cost you 1/2 what the new cost is.
02 October 2003, 12:44 AM
#86
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pleasure
Just as an aside, if you are removing the handbrake cable you will be making the car illegal. You have to have a seperate system that operates the brakes, independant of the footbrake hydraulic system.
Thats the law and you can be failed on rally scrutineering if that isnt fitted. Most rally cars have a dummy cable system to get round this. *cough*
[Edited by johnfelstead - 2/10/2003 12:47:38 AM]
Just as an aside, if you are removing the handbrake cable you will be making the car illegal. You have to have a seperate system that operates the brakes, independant of the footbrake hydraulic system.
Thats the law and you can be failed on rally scrutineering if that isnt fitted. Most rally cars have a dummy cable system to get round this. *cough*
[Edited by johnfelstead - 2/10/2003 12:47:38 AM]
01 December 2003, 02:32 PM
#89
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read this thread too. I explain a bit about how to use the control to avoid the clunking. http://www.scoobynet.co.uk/bbs/threa...hreadid=165543
cut and paste it says.
basically, the slower you go, the less diff lock you want in there, unless you are using the diff to drag you through mud, gravel or snow.
If you think about it and experiment it will become quite clear. You dont want to be doing slow manouvers like parking with the diff locked, you want it open. As you start to pick up speed the natural slip in the tyres removes the mechanical shock loadings you are feeling.
I tend to reduce the lock as i am slowing down for tight manouvers, you should be able to feel the loads building in the steering and balance the lock ratio based on that feel.
There seems to be a misconception from a post above that you have to stop to make an adjustment. Thats not the case, best way to do this is increase the lock as you increase the speed, it is totally analogue, so play with it and you will get a feel for what works best. I vary the lock constantly as road conditions change, it's dead easy once you practice and becomes second nature.
Reversing etc, just leave it diff open unless you get into a low traction issue such as in snow.
When you come to trafic lights, put the handbrake on. This unlocks the diff and stops you sitting there with the gearbox all bound up, when you drive off and remove the handbrake the diff setting goes back to the lock ratio you have already set.
I expect the new DCCD-A will have a map in it that drops the diff lock as speed drops, so people dont ever feel the juddering. I do the same thing myself automatically. I dont drive around at 10MPH into a carpark with the diff locked up.
Using this diff properly isnt black and white, which is why for years people have been scared to death of experimenting. If you do it right you will only get a rare ocurance of juddering and you should aim at avoiding that. The only time i get it now is when i have a wheel off teh ground in a tight chicane and the diffs are spinning up to lock.
One thing you may also need to consider is you should get the gearbox oil changed every 12,000 miles or so if you are making use of this diff.
[Edited by johnfelstead - 1/12/2003 2:36:07 PM]
cut and paste it says.
basically, the slower you go, the less diff lock you want in there, unless you are using the diff to drag you through mud, gravel or snow.
If you think about it and experiment it will become quite clear. You dont want to be doing slow manouvers like parking with the diff locked, you want it open. As you start to pick up speed the natural slip in the tyres removes the mechanical shock loadings you are feeling.
I tend to reduce the lock as i am slowing down for tight manouvers, you should be able to feel the loads building in the steering and balance the lock ratio based on that feel.
There seems to be a misconception from a post above that you have to stop to make an adjustment. Thats not the case, best way to do this is increase the lock as you increase the speed, it is totally analogue, so play with it and you will get a feel for what works best. I vary the lock constantly as road conditions change, it's dead easy once you practice and becomes second nature.
Reversing etc, just leave it diff open unless you get into a low traction issue such as in snow.
When you come to trafic lights, put the handbrake on. This unlocks the diff and stops you sitting there with the gearbox all bound up, when you drive off and remove the handbrake the diff setting goes back to the lock ratio you have already set.
I expect the new DCCD-A will have a map in it that drops the diff lock as speed drops, so people dont ever feel the juddering. I do the same thing myself automatically. I dont drive around at 10MPH into a carpark with the diff locked up.
Using this diff properly isnt black and white, which is why for years people have been scared to death of experimenting. If you do it right you will only get a rare ocurance of juddering and you should aim at avoiding that. The only time i get it now is when i have a wheel off teh ground in a tight chicane and the diffs are spinning up to lock.
One thing you may also need to consider is you should get the gearbox oil changed every 12,000 miles or so if you are making use of this diff.
[Edited by johnfelstead - 1/12/2003 2:36:07 PM]
20 January 2004, 07:54 AM
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Great thread here, just been linked from Scoobycity.
Is Jonh still monitoring this thread as i have a question.
I have a 99 Type R. 5
Both front typres are wearing badly on the outer walls.
Is the steeing set up different from a UK Turbo ? , as the Computer system that carries out the 4 wheel allignment only had the UK Turbo listed ?
One other one, when diff control is fully open in the green, if reversing the car the wheels judder as if the diff lock is on.
Is this normal ?
Cheers,
Brian, Events Organiser for Scoobycity.
[Edited by Brian the Sn@il - 1/20/2004 4:14:19 PM]
Is Jonh still monitoring this thread as i have a question.
I have a 99 Type R. 5
Both front typres are wearing badly on the outer walls.
Is the steeing set up different from a UK Turbo ? , as the Computer system that carries out the 4 wheel allignment only had the UK Turbo listed ?
One other one, when diff control is fully open in the green, if reversing the car the wheels judder as if the diff lock is on.
Is this normal ?
Cheers,
Brian, Events Organiser for Scoobycity.
[Edited by Brian the Sn@il - 1/20/2004 4:14:19 PM]