2WD-L transmission mode

Introduction

[this article is still in the making - more changes and additions are planned to be written]

Jimny has part-time four wheel drive transmission system. That means that the engine nominally drives only the rear axle (rear wheel drive). Since only two wheels are driven, that is called "2WD" mode.

The driver can manually engage "4WD(-H)" mode. In that mode, the front axle and front wheels get connected to the transmission as well, and then all four wheels receive engine power.

Constraints of 4WD and 4WD-L modes

However, because the transfer box contains no center differential, the front and rear propeller shaft always have to rotate at the same speed in 4WD mode. This in practice means that Jimny must not be used on non-slippery surfaces when in 4WD mode (except for very short distances and ONLY going dead straight). Otherwise, the transmission can be severely damaged! If steering to left or right must be done while Jimny is in 4WD mode, the road surface must be very slippery for the transmission to be able to relieve the tension caused by the lack of center differential. Wet tarmac roads are typically not slippery enough for 4WD, nor are hard gravel and dirt roads, nor dry grass fields.

Now, Jimny also has low range gears, meaning that it can effectively halve all of its gears' speed while doubling the torque. That functionality is essential for any serious all terrain duty, and very helpful even on gravel roads of varying constitution.

However, Jimny's transmission controls (both older stick-style mechanically operated and newer push-button-style electrically operated) allow the low range to be engaged only if 4WD is already engaged. Therefore, Jimny allows only "4WD-L" mode to be used.

This means that low range mode is always severely constrained by the above mentioned disadvantages of ordinary (high range) 4WD mode.

Reasons for having 2WD-L mode

On the other hand, in practice there can be several situations where "2WD-L" mode would be desired - using low range gears without 4WD mode. In that mode, steering would be safe to do on any kind of surface.

Typical situation is when driving on a dry, rough, twisty gravel or rocky road. On such roads, steering is applied a lot, the road surface is difficult so requires 1st low gear or 3rd low gear, but the road surface is not slippery. Using 2WD-L mode would be ideal.

Another useful situation for 2WD-L mode would be to tow a trailer some short twisty distance, or to make an easier start with a trailer when going uphill.

Also, parking in and out of difficult (sloped) parking positions would be much easier with 2WD-L mode.

Possibility of having 2WD-L mode

So, how to "enable" 2WD-L mode?

Technically, 2WD-L mode can work in Jimny's transmission system. Simply don't connect the front propeller shaft to the transfer box, and don't engage the front wheel hubs. This can be done manually by removing the front propeller shaft and disabling the vacuum system for the front wheel hubs. However, 4WD mode would be permanently lost (until everything is returned back).

Suzuki could have simply made the 2WD-L mode possible by making another "program / position" its 4WD controller, where the controller would only operate the low range selector in the transfer box, and leave the front propeller shaft and the front wheel hubs disconnected. But they did not, either because of lack of thought or because some smart slick manager thought that adding one more transmission mode would confuse a typical user.

So, the question is how to add/enable the 2WD-L mode "systematically", to be selectable any time from the cabin and to be compatible with the 4WD controller and all the mechanicals.

The solution depends if the Jimny has older stick-style mechanically operated transfer case, or newer push-button-style electrically operated transfer case.

Solution for older stick-style mechanically operated transfer case

More on the specific solution later on ...

Solution for newer push-button-style electrically operated transfer case

More on the specific solutions later on ...

---

Page last edited on 26/12/2016 by user Bosanek