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Old 27th April 2009, 16:26   #226
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That was a comprehensive, peice by peice dissection by Arka, I am learning.

Last edited by fazalaliadil : 27th April 2009 at 16:28.
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Old 27th April 2009, 16:59   #227
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Default CJ 340 outdone?

I agree with samurai, considering the incline is very slippery and if he starts just at the base, he will slip. Even if he slots first low and leave the accelerator he would still spin the wheel as there would be no or little traction. Gurkha managed it because-

1. Diff locks
2. Had enough low end torque enough to clear short incline

This is a classic case where diff locks will out do a open diff vehicle. Diff locks are invented with a purpose and it shows here.

P.S- This does not declare Gurkha a better offroader than legendary CJ 340. This is one off terrain and situation where Gurkha excelled and i would like many more to be discovered though. Heck... it had to do better some where to justify the astronomical price. Good job Gurkha (the vehicle)

Last edited by vinod_nookala : 27th April 2009 at 17:00.
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Old 27th April 2009, 17:00   #228
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Default Torque to Weight Index

Vehicle Weight in lbs
CJ340 (CJ3B + 40kgs i.e KMT90) = 1017+ 40 = 1057Kgs/2325lbs
Gurkha = 1700 (approx) = 1700kgs/3740lbs
CL550(MAJOR) = (CJ3B + 150Kgs) = 1167Kgs/2567lbs

Divided by engine torque
CJ340 - 12.3kgm/84ft/lbs i.e 2325/83 = 28.01
Gurkha - 19kgm/133ft/lbs i.e 3740/133 = 28.13
MAJOR - 18Kgm/126ft/lbs i.e 2567/126 = 20.37

More Torque or Lesser Weight can offset this index.

Torque to Weight with Mechanical Advantage (gearing)

Total Gearing X Engine Torque
CJ340 = 3.986 X 2.46 X 5.38 = 52.75:1 X 83ft/lbs = 4375ft/lbs
Gurkha = 4.695 X 2.02 X 4.9 = 46.47 X 133ft/lbs = 6180ft/lbs
MAJOR = 4.3 X 2.46 X 3.73 = 39.45 X 126ft/lbs = 4971ft/lbs

Divide Vehicle Weight with above
CJ340 = 2325/4375 = 0.53 i.e 53 percent
Gurkha = 3740/6180 = 0.60 i.e 60 percent
MAJOR = 2567/4961 = 0.51 i.e 51 percent

Vehicle Weight can be described as a percentage of Total Torque at the wheels.

The REAL Advantage JEEPs have is in the garage.

We can Change the engine or the Diff-Ratios .

Regards,

Arka
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Old 27th April 2009, 17:10   #229
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So diff locks have no advantage over open diff? Is that why its better to change diff ratio or engine rather than changing the diff to a lockable one?
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Old 27th April 2009, 17:17   #230
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Default Diff-Locks vs Diff-Ratio

Quote:
Originally Posted by tsk1979 View Post
So diff locks have no advantage over open diff? Is that why its better to change diff ratio or engine rather than changing the diff to a lockable one?
I can't believe you just said that!!!!

What does a differential Lock do.

Facilitates both Wheels to Rotate at the same speed.

There by transferring equal torque to each wheel.

This helps when you are likely to lift a when due to lack of axle articulation.

In the above scenario Diff-Locks would definitely help but were not everything.

Locking differential - Wikipedia, the free encyclopedia
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Old 27th April 2009, 17:21   #231
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Differentials and Diff Locks for Four Wheel Drives 4WD

Diff Lock Article

more professionally written and with pics!!
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Old 27th April 2009, 17:22   #232
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Default Seeing is believing

hmnn..
This is getting interesting, samurai now only a video will do. Figures suggest something and the actual experience something else. Would be interesting to see
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Old 27th April 2009, 17:22   #233
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Quote:
Originally Posted by ex670c View Post
I can't believe you just said that!!!!

Actually I got confused. I thought maybe you are saying that lack of engine power and gear ratio error was the cause of the problem here, not open diff
Quote:
What does a differential Lock do.

Facilitates both Wheels to Rotate at the same speed.

There by transferring equal torque to each wheel.

This helps when you are likely to lift a when due to lack of axle articulation.

In the above scenario Diff-Locks would definitely help but were not everything.

Locking differential - Wikipedia, the free encyclopedia
Yup, aware of this.
So on a sandy incline even if you are not going to lift, won't a diff lock help. In the safari on a sandy incline(no articulation issues), I had one front wheel spinning, one rear wheel spinning, and the other rear wheel slowly rotating(LSD).
I was unable to climb in 1st low. Then I came in 2ND low and charged at the incline, and was able to climb.
So if I had lockable front and rear diffs, all the 4 wheels would have spun, and the climb would have been possible, right?
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Old 27th April 2009, 17:30   #234
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Torque to weight ratio is a very confusing number. Torque only acts if there is enough resistance in the system. For instance if a motor produces 60NM to torque and a load of 10kgs act's against it, then the motor, no matter what amount of torque it produces, will only produce enough force to overcome that number.
I know it sounds absurd, especially since i myself am modding the Jonga for the 80kgm cummins motor, so its all going to be overkill (by the way, the Jonga diff-lock fab project is half complete, and we're getting closer everyday. All thats troubling me now is a way to move the locking ring. I can use the one from the gurkha, but i don't think its available). In my case, if the vehicle never gets into a situation that warrants the need for that amount of power, then the motor is probably never going to see those figures. But hey, who does'nt like more power, and its alway better than just about substantial power to inch forward. Those numbers, even if i never get to see them offroad, would sure as crap burn the rubber out on the road during acceleration.

As for momentum, i fully agree with Arka, but there are a few situations that can only be overcome with it. Look at the folks climbing the rocks. The run buggies with blown v8, which i think easily produce something on the better side of 50kgm. The drivetrain generally includes NV4500's and Atlas xfercases, so the overall ratios top 200:1. All that power produced by the gears and the motor is enough to pull the mount everest all the way to kanyakumari, so just think the shear amount of acceleration these rigs have. The only purpose for all this power comes to play when overcoming very steep slippery hills, where slow and sturdy doesn't get you anyplace. They pull off with as much momentum they can gather once they get the line to follow and place they rigs there.
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Old 27th April 2009, 17:37   #235
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Quote:
Originally Posted by vinod_nookala View Post
P.S- This does not declare Gurkha a better offroader than legendary CJ 340. This is one off terrain and situation where Gurkha excelled and i would like many more to be discovered though. Heck...
Exactly, in this terrain, Gurkha won hands down. It also wins in highway drives to far off OTR locations and ride comfort over the CJ340. The CJ340 has the advantage of lower weight, smaller body and smaller wheelbase.

Last edited by Samurai : 27th April 2009 at 17:38.
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Old 27th April 2009, 17:52   #236
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Quote:
Originally Posted by Samurai View Post
Exactly, in this terrain, Gurkha won hands down. It also wins in highway drives to far off OTR locations and ride comfort over the CJ340. The CJ340 has the advantage of lower weight, smaller body and smaller wheelbase.

CJ340 but murders Gurkha when you start talking about the budget.

Samurai I have also experienced that with Gurkha I dont need to rush it but just slightly push it!

Hopefully someday I am able to answer few queries like you guys as well
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Old 27th April 2009, 18:15   #237
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Quote:
Originally Posted by rhandle View Post
CJ340 but murders Gurkha when you start talking about the budget.
I didn't want to compare prices since you can't buy a new CL340.
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Old 28th April 2009, 13:49   #238
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Samurai, can you post a video of the gurkha doing the same incline from a standing start,..vs the rolling one you had on your CL340.
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Old 28th April 2009, 16:05   #239
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Sorry, Gurkha is already back in Bangalore, can't take any videos now.

Last edited by Samurai : 28th April 2009 at 16:06.
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Old 29th April 2009, 15:46   #240
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Quote:
Originally Posted by Torque-ative View Post
Samurai, can you post a video of the gurkha doing the same incline from a standing start,..vs the rolling one you had on your CL340.
Where are you Naveen, and I am sure you have seen the Gurkha in action!
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