Discovery TD5 52 plate centre diff lock

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Mark Ormond

Active Member
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253
Location
Derby
To reinstate diff lock i need to buy a lever and cable assembly which is about £250 wow
Can anyone tell me is it possible to use lever and cable off another Disco say 300 TDI.
All above is assuming my box has the gubins in it.
Many thanks
Mark
 
you can use parts from a 300 tdi youd need
gear box top assembly
transfer box hi/low lever and housing
cab lever and housing
linkage and pivot,hi/lo as well as difflock
not essential but tunnel rubber cover
 
Yes it has TC but diff lock works with it as an excelent compliment. you need to spin for TC to work diff lock helps stop that so even better
Good to know 300 TDI bits will do it i can find one of those
many thanks for that
 
Hi many thanks for the Link will take a look
Would be very interested why you think applying the brakes to spinning wheels which is basicaly TC wont work with Diff lock
 
LR made it so for a reason, on latest modells the ECU has an addapted internal map to suit the locked diff conditions which includes brake overheat prevention like with HDC but letting the TC fully operational with locked diff(cutting the input to ECU) will end up in overheated brakes and reduced torque when it's more need of it also dangerous levels of EGT... it's a complicated theory and implies a deep intrusion in how the wabco system is conceived to manage TC, IMO more complicated than it appears at first sight, it's not just about the fact that TC puts brakes on a spinning wheel... it's about how and an algorythm of pressure distribution within the modulator based on all 4 wheel speed sensor inputs ...dont get me started with this cos you'll all be bored and confused. :cool:

in a nutshell, dont mess with the TC with "normal" setup cos it's not healthy for the braking system, if you want the best of it better fit an uprated SLABS ECU(SRD500070) and let it work together with the locked diff as it was conceived.
 
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obviously over use of applying brakes will cause heat ,but what would be the difference between a locked center diff and unlocked if ecu doesnt know ifs locked
 
You tell me what's the difference between these two scenarios, then i'll tell you from wabco point of view ;)
1. unlocked central diff, FL wheel turns faster than FR and RR faster than RL
2. locked central diff in the same situation
there can be a variety of all kind of such scenarios and in each situation the ABS system will behave accordingly... the gist is that the ABS system when it comes to TC has a delay compared to mechanical actions

As i said it's more complicated than it appears, and the main issue is exactly the fact that the ECU doesnt ''know'' the CD is locked and will act like it isnt using brakes to equalise the axle speeds based only on wheel speed inputs while the axle speeds are already similar due to the locked CD
 
sierrafery said:
You tell me what's the difference between these two scenarios, then i'll tell you from wabco point of view ;)
1. unlocked central diff, FL wheel turns faster than FR and RR faster than RL
2. locked central diff in the same situation
there can be a variety of all kind of such scenarios and in each situation the ABS system will behave accordingly... the gist is that the ABS system when it comes to TC has a delay compared to mechanical actions

As i said it's more complicated than it appears, and the main issue is exactly the fact that the ECU doesnt ''know'' the CD is locked and will act like it isnt using brakes to equalise the axle speeds based only on wheel speed inputs while the axle speeds are already similar due to the locked CD
Click to expand...
ecu wouldnt know center diff lock is locked, there are numerous combinations of wheels spinning some of those been the same as diff locked when it isnt ie 2 wheels on the same side,
 
jamesmartin said:
ecu wouldnt know center diff lock is locked,....,
Click to expand...
I'm not trying to argue just to discuss about that cos that's what i'm saying too... that the ECU will act like when the central diff is not locked even though it is and the algorithm is based on the presumption that the propshafts are spinning with different speeds so based on all 4 sensor's inputs it will apply brakes all around as to make the propshaft's speeds similar as well without being necessary, but the axles are forced by the locked diff to turn at the same speed already and this will enter in conflict with the applied brakes and as the axle's speed will not be reduced with the expected rate the ECU will increase the fluid pressure in the calipers through the modulator, it's almost like when the driver applies brakes and throttle at the same time on a straight road... i've made such tests with my own car and once in a mud trap where i've passed without problems with open diff and locked diff(with inhibited TC) when i attacked it with cut diff-lock input to ECU i lost all motion in the middle of the mud with TC light on... important is to take into account that the TC has a certain delay cos it has to calculate while the mechanically locked diff is already acting
 
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sierrafery said:
I'm not trying to argue just to discuss about that cos that's what i'm saying too... that the ECU will act like when the central diff is not locked even though it is and the algorithm is based on the presumption that the propshafts are spinning with different speeds so based on all 4 sensor's inputs it will apply brakes all around as to make the propshaft's speeds similar as well without being necessary, but the axles are forced by the locked diff to turn at the same speed already and this will enter in conflict with the applied brakes and as the axle's speed will not be reduced with the expected rate the ECU will increase the fluid pressure in the calipers through the modulator, it's almost like when the driver applies brakes and throttle at the same time on a straight road... i've made such tests with my own car and once in a mud trap where i've passed without problems with open diff and locked diff(with inhibited TC) when i attacked it with cut diff-lock input to ECU i lost all motion in the middle of the mud with TC light on... important is to take into account that the TC has a certain delay cos it has to calculate while the mechanically locked diff is already acting
Click to expand...
im not trying to argue either just understand, ecu must have the ability to deal with 2 wheels spinning on the same side with equal axle speed,
 
Yes, if both wheels are spinning with the same speed(which is quie unlikely) then it doesnt matter if it's locked or not, but if only one wheel is spinning or they are spinning with different speeds or both wheels on one axle are spinning with different speeds while the others not with locked diff then it's problem.... i'm sure that's why on old ECU's the TC is inhibited with locked diff and on the uprated ECU it has a special map with a different algorithm and brakes overheat prevention protocol to suit the locked diff, wabco made serious tests for that i've studied lots of official documents with scientific explanations about it.... though everybody can make his own tests with fully operational TC and locked diff to understand... there are few cases when it can help but many more risky scenarios
 
sierrafery said:
Yes, if both wheels are spinning with the same speed(which is quie unlikely) then it doesnt matter if it's locked or not, but if only one wheel is spinning or they are spinning with different speeds or both wheels on one axle are spinning with different speeds while the others not with locked diff then it's problem.... i'm sure that's why on old ECU's the TC is inhibited with locked diff and on the uprated ECU it has a special map with a different algorithm and brakes overheat prevention protocol to suit the locked diff, wabco made serious tests for that i've studied lots of official documents with scientific explanations about it.... though everybody can make his own tests with fully operational TC and locked diff to understand... there are few cases when it can help but many more risky scenarios
Click to expand...
tc was inhibited for roller testing with prop off which is obvious as a reason,admittedly there are other scenarios apart from 2 wheels spinning on the same side both axles equal speed ,but since that scenario exists and can be expected to,ecu must deal with it and so not need to deal with more complicated scenarios,brake over heat will occur if tc is used for prolonged times or prolonge down hill,though rare given speeds its needed at,and more unlikely with locked center diff
 
I'm not sure i understand what you mean, what i mean in a nutshell is that WABCO knew why they made that locked diff input to inhibit or restrict the TC and after i've studied how they engineered things i entirely trust them on this... there's no brake overheat risc with TC normal operation cos when brake is applied on a spinning wheel it will stop as expected but the locked central diff can force the wheel to spin against the applied brake if there's enough torque or loose motion with low power if the brake "wins", only with HDC the brake overheat thing is actual cos the gravitational motion of the downhill rolling car forces the wheel to spin against the applied brake pressure exactly like the locked diff can do.
 
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