Center Clutch Gtr R33. How Strong ? How To Do The Torque Splitting ?

[Transpass]

So it's exactly the same as a viscous coupling? (-> http://auto.howstuffworks.com/differential5.htm)

But how's the pump driven/controlled? Electrically, additional clutch or bypass valve? (would be useful to know)

[jogge]

As far as i remember, there's not much of a difference. R33 GTR box has 2 vents at the top (small and black) and a pull type clutch actuation - means the holes for the hydraulic clutch cylinder are behind the opening for the fork/arm. The R32 GTR box is a push type system. You can change the R33 GTR box from pull to push if needed (drill 2 holes in front of the opening for the fork/arm and get them threated M8 or M10 [not sure about that]).

Setting the torque split to less than 100% permanently would cause a lot of wear - just like a normal clutch sliding the whole time. Especially under hard racing conditions with such an amount of torque. Another issue: heating up (?)

As GTRNUR said: The system wasn't designed for long time AWD. Maybe there's a way to change the clutch packs to a longer lasting material or to put a complete new diff into the existing housing.

but what is about to set it permanently to 50:50 ?

is it also always sliding then, or is it full pressured on to have full AWD ?

the art of construction of the GTR box is nearlly similar to the Cossi 4x4 box.

only the cossi-box has a permanent torque split of 33/66 with a visco-couple in it.

so i will think about the option to fit a visco-couple to the transfer case of the GTR box which is fix set to 30:70.

but this would be only second option.

best would be drive it with the active torque split via a electronical controller.

next week the man who had studid electronicall pneumatics is back from holiday and i will talk to him what to do.

i think best would be to build a controller unit which bases on the wheel speed sensors and g-sensor of the cossi. this should controll a oilpump system in which we will use a gearbox oil pump.

this pump is biuld to run continously. and we will also fit a cooler to the system.

the only thing is to find a gearbox oil pump which produces enough pressure.

but next week i think i can sort that out.

[Duncan]

you are better just to use the standard GTR pump and accumulator. you just need a pulse width modulator output from whatever control unit you want to use.

plenty of skyline race cars have tested various split levels, and the quickest has almost always been 50/50 fixed - however due to the much small front diff and driveshafts this most often ends with broken front bits. of course 50/50 may not be the best for your car, but it is about right for the skyline chasis.

[jogge]

you are better just to use the standard GTR pump and accumulator. you just need a pulse width modulator output from whatever control unit you want to use.

plenty of skyline race cars have tested various split levels, and the quickest has almost always been 50/50 fixed - however due to the much small front diff and driveshafts this most often ends with broken front bits. of course 50/50 may not be the best for your car, but it is about right for the skyline chasis.

how do they do that without wearing out their center clutch ?

yes for the cossis´also 50:50 is best and fastest on track. a lot of hillclimb and circuit race cossi´s drive that kind of splitting.

i also want to do that in the future but now my front diff is the weakest point of the drivetrain.it´s already uprated with qauife case,quaife internals and a steelplate is also fitted to the case to strenghten the case. but it´s still not strong enough.

if a want to have the front diff strong enough, i had to build in a 7.5 inch diff with quaife internals. and also i have to change driveshafts for something with prop-bearings.

[Duncan]

sorry mate, no idea on life of the clutches at 50/50 split, although I could guess it may be better for them because they may not be slipping.

[jogge]

sorry mate, no idea on life of the clutches at 50/50 split, although I could guess it may be better for them because they may not be slipping.

this is the same i think/hope.

but until now nobody know´s exact about this...

Edited August 31, 2010 by jogge

[doo doo]

wear will come from difference in wheel speeds while clutches are engaged. 50/50 is a strong enough engagement to break front drive gear on track powered cars.....you'd be spinning both front and back wheels before clutches are slipping when engaged at 50/50. The transfer is not like a viscous coupling which slips before you get traction, but that it grips to create traction for the front. More grip (more hydraulic pressure), less slip.

[Transpass]

There seems to be a misunderstanding

Correct me if i'm wrong:

The rear diff is driven directly by the main shaft, so there's not a real "central differential" (CD). If it would be a CD, then the prop shaft to the rear diff would be mounted to the backside of the side housing, opposed to the front drive shaft.

Torque split doesn't mean to have different wheel RPM front and rear (as doo doo said). As long as there's any torque split (no torque split means 0:100) front and rear wheels should (simplified) turn at the same speed in normal/perfect driving conditions and you got no wear on the clutch packs. You can change the amount of split torque to the front - by changing the oil pressure in the clutch pack (bell) housing - up to a maximum of 50% (most real CDs are able to manage more than 50% front wheel torque). This also means: It should be impossible to do a front wheel burnout whilst the rear wheels are doin' nothin'.

So, with standard ATTESA, the only time the clutch pack can wear out, is when the front and rear wheels are turning at different speeds; this should only happen, when you got more torque at the wheels than grip. Usually the dynamic weight at the front is less than the rear (also with a heavy front mounted engine!) and you won't need a 50:50 torque split - especially when the front diff is the weakest link of the chain. In real life there's wheel slip (~proportional to the torque) all the time and so there's also clutch wear all the time... if you don't set it near 50:50.

@doo doo: There are a lot of viscous coupling styles on the market, today. Can't see the big difference - you may have a look at this website.

Tranny pic is taken from GTBITZ.com.

[jogge]

There seems to be a misunderstanding

Correct me if i'm wrong:

The rear diff is driven directly by the main shaft, so there's not a real "central differential" (CD). If it would be a CD, then the prop shaft to the rear diff would be mounted to the backside of the side housing, opposed to the front drive shaft.

Torque split doesn't mean to have different wheel RPM front and rear (as doo doo said). As long as there's any torque split (no torque split means 0:100) front and rear wheels should (simplified) turn at the same speed in normal/perfect driving conditions and you got no wear on the clutch packs. You can change the amount of split torque to the front - by changing the oil pressure in the clutch pack (bell) housing - up to a maximum of 50% (most real CDs are able to manage more than 50% front wheel torque). This also means: It should be impossible to do a front wheel burnout whilst the rear wheels are doin' nothin'.

So, with standard ATTESA, the only time the clutch pack can wear out, is when the front and rear wheels are turning at different speeds; this should only happen, when you got more torque at the wheels than grip. Usually the dynamic weight at the front is less than the rear (also with a heavy front mounted engine!) and you won't need a 50:50 torque split - especially when the front diff is the weakest link of the chain. In real life there's wheel slip (~proportional to the torque) all the time and so there's also clutch wear all the time... if you don't set it near 50:50.

@doo doo: There are a lot of viscous coupling styles on the market, today. Can't see the big difference - you may have a look at this website.

hi,

yes the wheel rpm in front and rear is always nearly identical.only if you have less grip at one of the wheels it is different. but this usually is corrected by the traction controll.

50:50 is better for race driving, because if you turn in a corner to fast, and the car beginn to slide, it´s easier to get the car in a straight line with more torque at the front wheels.

to do a good controlled drift it´s better to have more torque at the rear.

but on track drifting is always slower than "normal" cornering.

so also 30:70 is a real good choice.

what´s better 30:70 or 50:50 depends also on the drivers style to drive and of course on the diff setup of the front and rear axle.

[Transpass]

@jogge:

Don't know the events, you're driving at (when you use it as a daily driver, too), but most Gabat Escorts are driving at Hillclimb races. There's a lot more dynamic weight at the rear because the car is accelerating uphill - and it's accerelating like hell

If i were you, i wouldn't go with 50:50 at Hillclimb. A 30:70 setup seems more reasonable to me. It's a lot easier to steer into tight turns with more torque at the rear wheels, too.

If you're driving at typical tracks like Nürburgring or Hockenheim (think i read that somewhere in this thread) then a 50:50 setup should be a good option. When using LSDs in front an rear, it won't be much of a loss if you make it 50:50 fixed - or lets say: lock it up. No clutch pack, no wear, no heating and less electronics!

[Transpass]

@jogge:

I'm sorry, but i can't answer your PM, cause i have to wait til i wrote 10 posts... maybe dumb comments like "cool" or "stunning project" hell - who got that idea?

You can send me your Email address or facebook, meinVZ, WKW... and i'll contact you.

[graham c]

hi am new here and i,ve just got my r33 gtr box its going in a mk1 escort 4x4 cosworth powerd jogge do you have any pic,s of the conversion plate the thickness? any other info would be great to

this is wot its going in

[Rolls]

that thing looks like it weighs 700kg, should be absolutely spastic.

[graham c]

not had it weighed yet its runnin 350 + and gas not much at min

[graham c]

any one ?