quick one. can you retrofit dccd?
#2
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The DCCD unit is part of the gearbox, and can be swapped over if required. The end casing will be different, to provide electrical connections to the unit for control.
You also need a controller at extra cost as your car won't have the wiring loom to do the job.
HTH
dunx
You also need a controller at extra cost as your car won't have the wiring loom to do the job.
HTH
dunx
#3
ok. Admitedly i have not looked at the scoob yet.
So the DCCD diff will mate to the classic gear box. Will this require new prop to fit?
Can you get standalone controllers what kinda cost are we talking about?
Just took the front diff off my bros evo, was really easy. hoping the scoob will be just as easy.
Would have to fit a nice **** in. Looks like you can get "kits" for a grand which is a bit rich tbh. Id rather keep my usable gear ratio and props with the ability to shuv more to the rear when on the track. Would really wanna spend more than 500, and not too much fabrication/adaptation unless there are off the shelf solutions.
Where is the dccd typically controlled from? I understand its a % setting for front to rear power so isnt going to require anything front wheel sensors etc? Or is it cleaver and will chuck power to the rear when the front looses grip?
This would be fitted onto a classic STI.
Any advice much appreciated
So the DCCD diff will mate to the classic gear box. Will this require new prop to fit?
Can you get standalone controllers what kinda cost are we talking about?
Just took the front diff off my bros evo, was really easy. hoping the scoob will be just as easy.
Would have to fit a nice **** in. Looks like you can get "kits" for a grand which is a bit rich tbh. Id rather keep my usable gear ratio and props with the ability to shuv more to the rear when on the track. Would really wanna spend more than 500, and not too much fabrication/adaptation unless there are off the shelf solutions.
Where is the dccd typically controlled from? I understand its a % setting for front to rear power so isnt going to require anything front wheel sensors etc? Or is it cleaver and will chuck power to the rear when the front looses grip?
This would be fitted onto a classic STI.
Any advice much appreciated
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The electric center diff is easy to change, I would allow 1 hr to do it, no changes required to prop or anything, you do need to swap the top plate that the wires go through which is tricky with the box in the car. The best way to control it is with a GEMS controller, it cost me £450 about 2 years ago, and it comes with 3 'active' maps and 3 static maps. Including full lock and handbrake release, it's a bit of a fiddle to wire it all up but not rocket science. Speak to Steve Simpson for more info 07836635001
Good luck.........Andy
Good luck.........Andy
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#9
Is it aong the lines of drop the fluid, rip out drive shafts, undo probably 6 bolts and drop the diff. Rebuild witht he control unit intot he cab somewhere. I could dive with a dccd **** rather than the dash display too.
Are you saying there is an aftermarket solution for this other than getting the diff from an RA/R? Or just an aftermarket control solution?
Also will changing to a DCCD with standard rear Diff and gearbox cause any chage in ratio or is it identical?
Its likley the car will be getting launched. Are these things hard enough to take 350bhp is launches?
Are there any difference between the different years dccd's which i should look for, from both best and compatible.
Are you saying there is an aftermarket solution for this other than getting the diff from an RA/R? Or just an aftermarket control solution?
Also will changing to a DCCD with standard rear Diff and gearbox cause any chage in ratio or is it identical?
Its likley the car will be getting launched. Are these things hard enough to take 350bhp is launches?
Are there any difference between the different years dccd's which i should look for, from both best and compatible.
Last edited by scoobyc; 27 April 2009 at 04:42 PM.
#10
How To: Center Diffs - RS25.com: Subaru Impreza GC8 & RS Forum & Community
wicked
http://www.type-ra.co.uk/vB/showthread.php?t=3015
Also wicked ish.
wicked
http://www.type-ra.co.uk/vB/showthread.php?t=3015
Also wicked ish.
Last edited by scoobyc; 27 April 2009 at 04:52 PM.
#11
ok. Need some more info on the 98 ish era DCCD. The neetronics looks like an awesome piece of kit. But i would assume that my car being non dccd it doesnt have all the sensors required to make it worth while?
Instead i ASSUME if i did fit a DCCD diff i would only get manual use not dynamic? THe idea of it cutting when handbreaking is nice. also so is launch control for the diff. That would be brill.
So is stil all possible just by chuving a dccd diff on the end of my gearbox and a bit of wiring? For a 98 i mean, or are these features only available on newer boxes which maybe dont fit my gb?
Instead i ASSUME if i did fit a DCCD diff i would only get manual use not dynamic? THe idea of it cutting when handbreaking is nice. also so is launch control for the diff. That would be brill.
So is stil all possible just by chuving a dccd diff on the end of my gearbox and a bit of wiring? For a 98 i mean, or are these features only available on newer boxes which maybe dont fit my gb?
#12
Ive got a replacement DCCD set up(complete) going into my type r at the moment. The cars in the tuners following a bearing problem with my original box. I will have a complete set up inclusing clocks, hubs, etc etc out of my type r as I dropped it out for the replacement (avoids diff problems). I'll have more details when i collect from the garage this week if your interested in some parts.
#13
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As I have already said, use the GEMS controller, it gives 3 active maps, handbrake release etc. it's not just a manual system. This is how most rally cars run the dccd, I have had this set up for about 2 years and have about 6 class wins with it, it's also easy to fit, just a bit of wiring.
Andy
Andy
#14
Ok Cool. rtm4676 yhpm
So if rtm4676 can supply me the center diff itself, all i need is the control unit and to fit it. From the readups of chaning the front diffs on subaru's it seems easy enough. Take some linkage off, undo 6 14mm bolts and pull it all out.
If i did go for the after market controll. Are they stand alone or is there other wiring required intot he cars loom also? Read some posts about incompatability with ABS. The idea of proper launch control appeals to my a alot. will my car have correctly inbuilt sensors to achieve this. G-sensor, steering angle, slip angle etc etc?
So if rtm4676 can supply me the center diff itself, all i need is the control unit and to fit it. From the readups of chaning the front diffs on subaru's it seems easy enough. Take some linkage off, undo 6 14mm bolts and pull it all out.
If i did go for the after market controll. Are they stand alone or is there other wiring required intot he cars loom also? Read some posts about incompatability with ABS. The idea of proper launch control appeals to my a alot. will my car have correctly inbuilt sensors to achieve this. G-sensor, steering angle, slip angle etc etc?
Last edited by scoobyc; 28 April 2009 at 12:07 PM.
#16
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To change the diff you need to remove the prop, the gear linkage and remove the tail housing, you may need to drop the gearbox mount to get at the top plate, pretty straight forward. On the classic you won't have g sensor, steering angle etc. The GEMS is connected to brake signal, handbrake, throttle position, live, earth and 2 wires to the diff unit, Steve will supply wiring info, took me a couple of hours to fit. You will need to find a place to mount it and where you want the control **** located.
#18
https://www.scoobynet.com/driving-dy...sti-works.html
DCCD Explained - ClubWRX Forum - Subaru Impreza WRX and STi Community and Forums
https://www.scoobynet.com/technical-...anslation.html
ok. been doing more reading and perhaps my understanding of DCCD is lacking some what.
In reference to racing on tarmac/wet tarmac and launches/power out of corners.
So the standard diff is effectivly open. And the most power given the rear wheels assuming the front has lost traction is a ratio of the torque required to spin the front wheels. So you could end up just spinning the front wheels.
So in that respect, a locked diff would be best for launches. So now power ist lost spinning the front wheels other than that put to the front wheels by the 35/65 split.
Now people say that chaning the lock makes the back end step out more on power out of corners due to a higher ratio of torque given to the rear wheels??
If the ratio is 35/65 and the diff is locked. why will that cause more torque to be sent to the rear wheels?
This attempts to explain why but i dont get it.
Can anyone reword this so it makes sense to me
Ill re-read it a couple of times.
DCCD Explained - ClubWRX Forum - Subaru Impreza WRX and STi Community and Forums
https://www.scoobynet.com/technical-...anslation.html
ok. been doing more reading and perhaps my understanding of DCCD is lacking some what.
In reference to racing on tarmac/wet tarmac and launches/power out of corners.
So the standard diff is effectivly open. And the most power given the rear wheels assuming the front has lost traction is a ratio of the torque required to spin the front wheels. So you could end up just spinning the front wheels.
So in that respect, a locked diff would be best for launches. So now power ist lost spinning the front wheels other than that put to the front wheels by the 35/65 split.
Now people say that chaning the lock makes the back end step out more on power out of corners due to a higher ratio of torque given to the rear wheels??
If the ratio is 35/65 and the diff is locked. why will that cause more torque to be sent to the rear wheels?
wheels on dirt and rear wheels on tarmac DCCD at 10% lock: Same premises as before but here it will take 50 ft-lbs to spin the front wheels and 200 ft-lbs to spin the rear wheels. Also let us set the DCCD so that it is only 10% engaged and so will slip at 5lbs. In this situation the point at which the clutch can’t transfer torque will occur before the point at which the front tires will slip. After that point any additional torque is divided in the 35/65 ratio, same as the open diff. That changeover point comes at an engine torque of 33.5 ft/lbs, at which point the actual torque at the axles is 6.7ft-lbs F/28.7ft-lbs R. If we increase engine torque to 100 ft-lbs, then the rest (66.5 ft-lbs) is split up 35/65 so we end up with a total actual torque split of 30 ft-lbs F/70 ft-lbs rear. If we then change the lock to 100%, the clutch can transfer all the torque difference (15 ft-lbs) and our “virtual driveshaft” analogy holds and so the torque difference is 20 ft-lbs F/80 ft-lbs R. So by changing the lock % we can change the torque distribution, even though there was no slip in the system.
Can anyone reword this so it makes sense to me
Ill re-read it a couple of times.
#19
Locked differential and front wheels on ice: As in the previous example, the torque on the front driveshaft that will cause the wheels to spin is 10ft-lbs. Just like in the first example, that is the max amount of torque that can be applied to the front driveshaft. Why? Because the conditions under the front wheels are still the same, the ice will only "push back" with 10 ft-lbs, so the front wheels can only "push" with 10 ft-lbs. This is very important to understand. You can't push against something if it won't push back. But since the driveshafts are locked together, the engine is free to apply more than 10 ft-lbs to its connection at front driveshaft. In fact, think of it as just one large driveshaft, with the engine twisting the shaft at two places (side by side), one with 35% of its effort, the other 65%. Fig 3, the locked case, shows this concept. If the engine applies 100 ft-lbs, what happens? 35 ft-lbs on the "front twist", 65 on the "back twist", but remember the front axle can only accept 10 ft-lbs. If the rear can take 90 ft-lbs before slip, then rest of the engine torque (90 ft-lbs) goes to the rear axle, which is (let us assume) enough to move the car. In this case the torque split is 10%F/90%R (I ignored the case where the rear can take more than 90 ft-lbs we’ll get to that below.)
HELP!
#20
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Put simply,the power is sent direct to the rear wheels, the center diff transfers power to the front wheels, the DCCD can be adjusted to vary the amount it sends, when fully open the car feels like RWD only. Essentially the 'tighter' the diff gets the more power is transmitted to the front wheels. If you ran it fully locked the car would feel horrible to drive, by actively varying the lock you get the best of both worlds. Not a fully techi explanation but tried to simplify it.
Andy
Andy
#21
ok give me the full on technical explaination then please with some maths
Its just not calculating in my head how it actually does it. The only way i can think contracdricts that it puts power to the rear.
So does a full Open DCCD make the car less understeery and more over steery than a non dccd? It seems the max power split with an open dccd is 35/65, the same as a non dccd diff?
Im not sure if the "diff" actually doesnt anything when it comes to putting power to the rear, more of has an effect when the front or the rear has lost traction.
Effectivly to put more power to the rear, neither front nor rear is spinning, so the dif is effectivly not slipping anyway..?
Its just not calculating in my head how it actually does it. The only way i can think contracdricts that it puts power to the rear.
So does a full Open DCCD make the car less understeery and more over steery than a non dccd? It seems the max power split with an open dccd is 35/65, the same as a non dccd diff?
Im not sure if the "diff" actually doesnt anything when it comes to putting power to the rear, more of has an effect when the front or the rear has lost traction.
Effectivly to put more power to the rear, neither front nor rear is spinning, so the dif is effectivly not slipping anyway..?
#22
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I wish i could give the full mathamatical explanation but me noooot that clever!!!!
The power to the rear wheels is constant, that does not vary as it is fixed, the variable is the amount the center diff locks and transmits power to the front wheels, in open mode it would give oversteer, which is what you want turning into a bend, effectively allowing the car to 'turn in' nicely, once the power is applied you want more lock to give max traction, also under braking you want it to be locked for max traction.
A non DCCD diff will vary depending on how old it is, the viscous unit goes 'slack' over time and the car would become more WD!
The power to the rear wheels is constant, that does not vary as it is fixed, the variable is the amount the center diff locks and transmits power to the front wheels, in open mode it would give oversteer, which is what you want turning into a bend, effectively allowing the car to 'turn in' nicely, once the power is applied you want more lock to give max traction, also under braking you want it to be locked for max traction.
A non DCCD diff will vary depending on how old it is, the viscous unit goes 'slack' over time and the car would become more WD!
#23
ok then. So will DCCD give more rwd than a standard diff?
I take it you could sale that a standard center diff (is it lsd?) has a percentage of Lock, where as the dccd can go from 0 to 100%
So under braking distributes the engine braking more evenly between the wheels???`
I take it you could sale that a standard center diff (is it lsd?) has a percentage of Lock, where as the dccd can go from 0 to 100%
So under braking distributes the engine braking more evenly between the wheels???`
#24
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Lol, CMS, I've just come across this thread and this is something I've often toyed with for my 05 wrx.
Wasn't anything to do with Rockingham by any chance..?
I'd love to have the ability to have more rear bias, if nothing else for a bit more fun. However, nearly everyone I spoke to about it reckoned it wasn't worth doing (ie DCCD's gimmicky). Having been in passenger in a DCCD-A car they're much easier to get the rear squirming/stepping out.
They most fun I had in my scoob was when my last set of tyres (toyo T1-rs) were on their last legs. Fitting GY F1A's after made the car almost boring by comparison..
Wasn't anything to do with Rockingham by any chance..?
I'd love to have the ability to have more rear bias, if nothing else for a bit more fun. However, nearly everyone I spoke to about it reckoned it wasn't worth doing (ie DCCD's gimmicky). Having been in passenger in a DCCD-A car they're much easier to get the rear squirming/stepping out.
They most fun I had in my scoob was when my last set of tyres (toyo T1-rs) were on their last legs. Fitting GY F1A's after made the car almost boring by comparison..
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ok then. So will DCCD give more rwd than a standard diff?
I take it you could sale that a standard center diff (is it lsd?) has a percentage of Lock, where as the dccd can go from 0 to 100%
So under braking distributes the engine braking more evenly between the wheels???`
I take it you could sale that a standard center diff (is it lsd?) has a percentage of Lock, where as the dccd can go from 0 to 100%
So under braking distributes the engine braking more evenly between the wheels???`
Andy
#26
Yeah i find my car a bit lacking in the corners. Ive got some stuff on the way to fix that, but it still feels like it needs a bit more power to the rear to push my out of the corners more rather then pull me. Might also make the font tyres get destroyed and overheated a little slower.
So really there are 3/4 reasons im thinking of doing it.
1. Would be nice to see how it increases my cornering and fun out of the corner.
2. More back end slidy when i want just fun.
3. I wanna see if i can do it
4. I wanna undestand it properly
So really there are 3/4 reasons im thinking of doing it.
1. Would be nice to see how it increases my cornering and fun out of the corner.
2. More back end slidy when i want just fun.
3. I wanna see if i can do it
4. I wanna undestand it properly
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ok with all this theory banging around has anyone done it - say a 1998 onwards dccd to a 1994 non dccd box
I have a 1994 classic 5mt and I have a dccd unit from a 1998 sti v4 5mt
before I rip everything out to swop it - are there any changes to the drop gears or is it just a normal centre diff out - kick it in the corner - fit the dccd unit - battle with the top plate and its done ? no issues with drop gears ? or ratios to drive the rear driveshafts ?
I have a 1994 classic 5mt and I have a dccd unit from a 1998 sti v4 5mt
before I rip everything out to swop it - are there any changes to the drop gears or is it just a normal centre diff out - kick it in the corner - fit the dccd unit - battle with the top plate and its done ? no issues with drop gears ? or ratios to drive the rear driveshafts ?
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