D1 vs. D2

GotRovr

Well-known member
Jun 16, 2004
377
0
Interesting thought. A working locked diff guarantees equal torque transfer to both wheels but does not guarantee traction. Assuming the CDL locked for both vehicles, I am curious about the comparison BTW a locked D1 to an open D2 w/ETC. The D1 will spilt torque 25% equally BTW front wheels, where the D2 is a biased system that could send 25% to 50% torque say to the left wheel while ETC is locking the right wheel using ABS modulation. What does this mean. As long as one front tire maintains grip for both vehicles, the D2 will guarantee the use of all 50% power compared to the D1 that can only guarantee 25% to the single wheel with traction. Even though my D1 has plenty of power (Stroked 4.0) and full lockers( ARB), I find that being the D1 is near gross weight coupled with 265?s or a marginal foot print pose a real challenge with certain terrain, especially slick rock. At a favorite obstacle at Hollister Hills slippery smooth concrete with embedded rocks.





I find it a real challenge to balance just the right amount of power to get up the steep incline without spinning all rubber. I find at times I have all 4 tires spinning. Now will an 04 D2 make it up any easier?, (less effort with less wheel spin). I watched in awe a little Samurai with 33?s or 35?s just walk up with no spin whatsoever
 

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Snwbord24

Guest
I get moderate wheel spin on that stair step with ETC, no CDL and 265/75's. Once you clear the first stair with some momentum it's nothing to get up. I think I do have more wheel spin than Stansell with ETC and CDL though. I watched a friend of mine in his J**p with ARB front and rear crawl up there with little to no spin at all.
 

Thai

Well-known member
Oct 17, 2004
48
0
49
Texas
www.t4r.org
Now, i don't have a Discovery...but i can lend some info.

I have a G500, which has both ETC and lockers (front & rear). When i lock my center diff or any of the lockers, ETC shuts off (along with ABS). If i don't lock anything, then ETC is on.

In Colorado back in 9/04, i went thru Engineer Pass with my '04 G500. Near intersection of Engineer and Poughkeepsie Gulch, there is a steep, somewhat slippery rock hill. With full lockers ON, i had no problem making it up...minimal wheel spin (with stock tires)...slow and steady.

With ETC ON (lockers off), i could not make it up, despite trying different paths. As i near the top, i slip. ETC was always a split second too late in braking the spinning wheel(s). And once the wheel(s) slips, i lost momentum. The transfer of power was very erratic (due to ABS pulsing the slipping wheel) and not constant.

Remember, ETC PULSES the brakes...it doesn't clamp down on the spinning wheel. Therefore, it only SLOWS down the spinning wheel to allow "some" torque to flow to the other side. It does this until the two wheels spin at the same speed.

ETC caNOT transfer 50% of power to one wheel because some of it is loss to heat. I see ETC as preventing the LOSS of power from one wheel (one with traction) as it's partner slips.

Hope this helps.
 

Ho

1
Staff member
in hungry valley, there's a similar concrete step:

DCP_0045.jpg


i took the new disco up that thing. first tried with open center diff. ETC only.
grinding noise, blinking lights, pumping shit, it was going crazy. some portions i had to give it some good gas. cuz ETC alone wasn't letting me just crawl over it.

then moved the CDL lever to the left. bam! almost no ETC kicking in. tremendous difference. ETC would still kick in. but much less harsh. more "crawlable"... no need for momentum.

but then... you guys already knew that. just had to rub it in..... cuz i know some of you still don't got that CDL thing. :)
 

kennith

Well-known member
Apr 22, 2004
10,891
172
North Carolina
Well,

I put the D1 CDL lever in quite some time ago and of course it makes a difference. Given a choice, however, between 3 lockers, and only one with etc...I'd take the three anyday.

Cheers,

Kennith
 

DeanBrown3D

Well-known member
Apr 29, 2004
765
0
www.discoweb.org
I think the failure of ETC is predominantly in the programming and algorithmic routines that are used, rather than in the hardware. It would be nice to have a higher 'resolution' on the wheel sensors though, and a higher resolution in brake-pressure regulation, but I think that a really clever algorithm to control spin could be better than full lockers. In an ideal world, a mud-filled tire would spin, free itself of muck, and then get back to work gripping with higher traction, all powered by a cray megacomputer (or at least a decent Intel chipset). But as it is now, the mechanism is too harsh and brash, it eats up brakes, and (so I've heard) promotes drive shaft breakage.

-Dean
 
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Discosid

Guest
My god this is getting very anal.
Its a Land Rover for god sake.
They are all very very capable.
QUOTE..,. THE BEST 4X4 BY FAR
And still to this day in my opinium
 

rovercanus

Well-known member
Apr 24, 2004
9,651
246
The best thing I've found to do on my 2000 D2 with CDL is to not let wheel spin start.
With the cdl engaged, I do my best to just keep steady on the gas pedal. Once a wheel starts spinning, it's much more difficult to maintain traction unlees you can get past the obstacle it's spinning on.
I do really like the combination of etc and cdl. I impress a lot of jeep folks that don't know Disco's.
 

Bruno

Well-known member
Apr 29, 2004
240
0
Ho said:
but then... you guys already knew that. just had to rub it in..... cuz i know some of you still don't got that CDL thing. :)

Nice... first Kyle, and now this sheit !

LOL,
Bruno.
 

Bruno

Well-known member
Apr 29, 2004
240
0
DeanBrown3D said:
I think the failure of ETC is predominantly in the programming and algorithmic routines that are used

The (BMW) Range Rover seems to do a better job of this.

Bruno.