![]() | #31 | |
Senior - BHPian Join Date: Oct 2005 Location: Faridabad/Delhi
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![]() | #32 | |||||
Senior - BHPian ![]() Join Date: Dec 2005 Location: Singapore, Mumbai, Nagpur
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It's the mismatch of speeds between the front axle and the rear axle. Let me explain. Do you agree that a two wheeler doing a "U" turn has a front wheel going faster than the rear wheel? For the same reason "GEOMETRY", the front axle needs to go faster than the rear axle in a front-wheel steered vehicle, while it is taking a turn. This causes a mismatch of speeds between the front axle and the rear axle. This is transmission wind-up. Don't try it or you'll have your front drive shaft twisted into a pretzel. Quote:
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Once the transmission is wound up, you will not be able to disengage front axle drive, unless you reverse the vehicle and unwind the transmission. Quote:
![]() I know what shift-on-the-fly means and have helped repair shift-on-the-fly mechanisms. In shift-on-the-fly four-wheel-drive applications, you need a component called a synchro. The synchro matches the speed of the front output shaft to the speed of the transfer case drive. It needs to spin the front driveshaft up to road speed before the front drive axle is meshed in. Of course in a primitive Mahindra, the front driveshaft spins all the time – the front wheels are never free of the front differential. Last edited by Ram : 31st March 2006 at 15:07. | |||||
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![]() | #33 | |
Senior - BHPian Join Date: Oct 2005 Location: Faridabad/Delhi
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![]() | #34 |
Senior - BHPian ![]() | ![]() What you have mentioned is absolutely correct, but transmission windup doesnot disqualify the SOTF feature, makes is more difficult to use. The synchro is not mandatory in a SOTF mechanism. The real cause for transmission windup is the lack of differential action in the G-Box-Tcase. The Dana/Spicer 18 T-case is recognised as a SOTF capable world over. The free-wheeling hubs fitted on M&M Vehicles are made by LAMBDA in Bangalore. These hubs are of 2 types 1) Permanent - Semi-Conical in shape with roller bearings 2) Selectable - Cylindrical ,Lock & Free Mechanism You did the Rubicon Valley.........................................CJ7 I presume |
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![]() | #35 |
BHPian Join Date: Mar 2006 Location: Mumbai
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| ![]() The legend doesnot even look like the military one that Mahndra's make. You can often spot the military version doing test runs on the Mumbai-Ahmedabad highway. They seem quite different (in terms of indicator lamps, height, tail lamps etc.) I see them very often (obviously in their olive green paints) however last week i spotted atleast a dozen or so of them in white paint. Maybe Mahindra plans to launch a civilian version which might not be in limited numbers. And this one did seem to be a perfect copy of the military one. Also i wonder why we dont have a civilian version of the jonga? |
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![]() | #36 | |
Senior - BHPian Join Date: Mar 2005 Location: N.A
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Last edited by Steeroid : 31st March 2006 at 20:48. | |
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![]() | #37 | ||||
Senior - BHPian ![]() Join Date: Dec 2005 Location: Singapore, Mumbai, Nagpur
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First think about this question: What makes shift-on-the-fly possible or impossible in a modern transfer case or gearbox? What makes any gear-shifting possible or impossible? The answer is “Shaft Synchronization” What impedes synchronizing your front propeller shaft with your transfer case? In two-wheel-drive mode in a modern part-time 4x4 with freewheeling front wheels, the front propeller shaft is stationary, while the transfer case is turning. The front wheels are spinning freely, leaving the rest of the system upto the transfer case, stationary – not consuming fuel, nor wear-and-tear. The front wheels have manually or automatically lockable hubs, or automatically lockable half-shafts. They are in the freed state. To shift into four wheel drive, the system must
Pros: You don’t have to get out in the mud and muck to lock your hubs. The integrated "shift-on-the-fly" system does that for you. While the hubs are free, you have better fuel economy and reduced front axle wear-n-tear. Cons: They need special maintenance. After some age they are fraught with vacuum leaks or stubborn solenoids. Quote:
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When driving on unyielding terrain such as a hard or rocky surface, the driveline cannot reconcile these speed differences. If a single wheel could lose traction and spin momentarily the torque-buildup would be defused. This, IMHO, defines the "transmission windup" phenomenon. I will explain with a diagram if Team-BHPians would like that! That being said, even an open differential will not solve the problem of optimum torque distribution. The Range Rover solves the problem of distributing torque without transmission windup with a viscous limited-slip center differential. Expensive Toyota/Lexus 4x4s use a torque-sensing "Torsen" limited-slip center differential. Some other high-end 4x4s use a driver-lockable center differentials. Quote:
The Spicer-18 is a prehistoric transfer case, that comes from before the times of locking hubs, leave alone automatically locking hubs. Because your hubs are permanently synchronized -- permanently locked with six bolts per hub, your Spicer-18 transfer case can be shifted-on-the-fly. But please understand, that it has no SOTF synchronizer so, it will not
In GTO's Mahindra Classic, he must stop the Jeep and manually lock the hubs. The fuel-wasting two wheel drive of the 4x4 Mahindra with bolted hubs, turns the half shafts, the crown and its planetary cage and the pinion and the front propeller shaft all the time. Not to mention the avoidable wear-and-tear on the front drive shaft “U” joints and the front differential. You lose the fuel economy and reduced wear-and-tear in two-wheel-drive possible with a true SOTF with autolocking hubs. You are deprived of the benefit of true two-wheel-drive. Calling a Spicer-18, an SOTF mechanism is like saying a cheap fixed focus camera performs like an autofocus, because the subject is luckily at infinity. Or like saying a stopped clock shows the correct time once in every twelve hours. Last edited by Ram : 1st April 2006 at 15:30. | ||||
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![]() | #38 | ||
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![]() | #39 | |
BHPian ![]() | ![]() Quote:
![]() Also, IMHO the 4 additional lights on the roll-bar and 2 on the front bumper are an overkill. A pair of Hella Rallye 3000 or a pair of KC Daylighters should suffice and look very good. | |
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![]() | #40 | |
BANNED Join Date: Feb 2005 Location: Mumbai
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![]() | #41 | |
Senior - BHPian Join Date: Mar 2006 Location: mumbai
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![]() | #42 | |
BHPian ![]() Join Date: Oct 2005 Location: Delhi
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I have driven an MM540 and a gypsy (1-litre version) extensively offroad. Whenever, I encountered "transmission wind-up" - or in layman terms if the darn thing wouldn't get out of 4H or 4L mode - I just had to reverse 10-15 feet, stop... and click... it would be as smooth as butter. | |
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![]() | #43 |
BHPian ![]() Join Date: Dec 2006 Location: Jakarta
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| ![]() Ram, Considering your indepth technical know how on 4x4's, how would you classify the technology employed by Suzuki. Is it at par with what you would expect from a competant 4x4. I am an absolute newbie when it comes to 4 wheel drives, and would be great to know how the gypsy stacks up technically. Cheers |
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![]() | #44 | |
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Distinguished - BHPian ![]() ![]() | ![]() Is it possible to fit free-wheeling hubs on the MM550? Does anyone have the contact number for LAMBDA in Bangalore who make free-wheeling hubs for M&M Vehicles. What is the spline count of the Dana 44 axles. I wanted to order diff lockers and the shop needs the spline count of the Dana 44. |
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