2WD-only Jimny to 4WD retrofit

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Introduction

• Suzuki used to produce an "el-cheapo" 2WD-only (rear wheel drive only) Jimny edition in the early production years (probably around 1999-2003).
• These Jimnys are quite rare, but still appear here and there from time to time on the used car market.
• 2WD-only Jimnys usually have (almost) no additional equipment.
  • Examples of additional equipment: longitudinal roof rails, power steering, power side windows, power mirrors, ABS, air conditioning, etc.

However, a 2WD-only Jimny might still be a compelling purchase.

• Reason 1: They are usually very cheap on the used car market.
• Reason 2: A 2WD-only Jimny can be easily retrofitted with missing 4WD mechanics for a relatively low cost.

Therefore, a 2WD-only Jimny in good condition, after being retrofitted with 4WD transmission, can be a cheap and reliable, albeit a basic (non-comfort equipped) all-terrain vehicle.

The purpose of this article is to provide guidelines on how to retrofit the missing 4WD system components into a 2WD-only Jimny, in order to transform it into a "full" 4WD Jimny (just like any other "normal" Jimny). The resulting vehicle will be fully equivalent to a factory 4WD Jimny, except for having manually operated or fixed front wheel hub heads instead of vacuum operated front wheel hub heads, which is actually a more robust solution.

If you already have a "normal" 4WD Jimny, you do not need to read this article. Go 4WD-ing already!

2WD-only Jimnys main specifications

• Most (if not all) 2WD-only Jimnys have G13BB engine and corresponding gear box and rear differential.
• Most (if not all) 2WD-only Jimnys use all five narrower wheels (exact wheel width not currently known) with tyres in size 175 / 80 / R15.
  • However some owners have changed them to standard Jimny 5.5J width 15-inch wheels and 205 / 70 / R15 tyres in the meantime.
• Most (if not all) 2WD-only Jimnys do not have ABS, and therefore some of their front and rear axle parts are not compatible with axle parts from ABS-equipped Jimnys.

2WD-only Jimny transmission setup

These are the transmission system components of 2WD-only Jimnys which are the same as in 4WD Jimnys:

• Manual gear box;
• Propeller shaft between the gear box and the transfer box;
• Propeller shaft between the transfer box and the rear differential;
• Entire rear axle assembly;
  • Rear axle assembly consists of: rear axle casing, rear differential, pair or rear halfshafts and a pair or rear wheel hubs which contain the wheel bearings.
    • Beware that some elements of the rear axle assembly differ for ABS and non-ABS equipped Jimnys.
• All suspension components;
  • These are: front and rear radius arms, front and rear panhard rods, front tie rods and tie rod ends, coil springs, shock absorbers, etc.

These are the transmission system components which are specific in 2WD Jimnys:

• "Dummy" transfer box;
  • This transfer box has only a simple fixed mechanism inside, just to physically inter-connect the gear box with the rear differential.
  • There is no lever in the cabin to control this transfer box, as there is nothing to control in it anyway.
    • Technically, the gearbox could have been connected directly to the rear differential through a very long propeller shaft.
    • However Suzuki chose to use this dummy transfer box in the middle, probably to keep the parts stock unified (to reuse the same small and rear propeller shafts as in 4WD Jimnys).
  • The casing of this transfer box is almost the same as the casing of a normal mechanically operated Jimny transfer box.
    • The casing was kept the same in order to keep the same distances for the propeller shafts toward the gear box and the rear differential.
    • However, this dummy transfer box casing has no "interface" for the front propeller shaft (toward the front differential).
      • Therefore, it would be impossible to connect the front propeller shaft to this dummy transfer box even if all the proper 4WD gearing inside it was reinstalled.
• Hollow ("dead") beam front axle assembly.
  • The front axle casing is hollow, and it does not even have a front differential casing.
    • It's a single-piece hollow tube from one wheel hub to another.
  • There is no pair of front halfshafts either, and no constant velocity joints in the wheel hub assemblies.
• Front wheel hub heads are (most probably) fixed or they do not exist at all.
• The front wheel hub assemblies still contain a pair of king pins and a pair of king pin bearings, and a wheel bearing too with a couple of seals.
  • However, many small pieces in the front wheel hub assemblies are missing (like some seals, retainer rings etc. which are part of the vacuum sealing system in 4WD Jimnys).

These are the transmission system components which are non-existent in 2WD Jimnys:

• Front differential.
• Propeller shaft from the transfer case to the front differential.
• Vacuum system (pipes, solenoids, tank, etc.) for the front wheel hub heads.
• 4WD controller computer.

Required parts for 4WD refitment

Transfer case, mechanically operated

• A standard, mechanically operated Jimny transfer case with all the gearing inside, together with a mechanical operating lever.
  • The transfer case is bolt-on compatible and will fit into a 2WD-Jimny like it's an original installation.

Front propeller shaft

• Front propeller shaft from any Jimny (even propeller shafts from newer Jimnys with push-button operated transfer box should be the same).
• If the universal joint in the front propeller shaft is worn, you will also need a new universal joint.
  • It is best to install a new universal joint at this point while the propeller shaft is not yet mounted.

Entire front axle assembly

This consists of:

• Front axle casing (tube);
• Front differential;
• Pair of front half shafts;
• Pair of CV joints;
• Pair of front wheel hub assemblies;
  • These consist of a wheel hub casing, pair of king pins, pair of king pin bearings, wheel bearing, and a lot of seals, c-clips, rings and other small parts

Pair of front wheel hub heads

• It is not recommended to install original vacuum locking front free wheeling wheel hub heads from a 4WD Jimny.
  • In that case, an entire vacuum system (solenoids, switches, pipes, tank, etc.) would then have to be retrofitted as well, as well as the 4WD control computer.
• A much simpler and more robust solution is to install manual (or even fixed) wheel hub heads instead.
  • These do not require the presence of any vacuum system element nor the presence of 4WD control computer.

• The wiki article "Manual or fixed front wheel hub heads" contains all the information (and more than that) about choosing and installing manual or fixed front wheel hub heads on a Jimny.
  • Concentrate primarily on part 1 (solutions 1a through 1d) in that article, as the other parts of that huge article are not that important for this case.

Some bolts and bushes

• If some of the bolts which connect the front shock absorbers, radius arms, panhard rod, anti roll bar links, etc. to the front axle happen to be seized, you will have to cut them off.
• A seized bolt in a bush usually means that it can not be taken out without destroying the bush too.

Therefore, you might need the following replacement bolts and bushes:

• Front shock absorber to front axle bolt and bush (two pairs in the worst case);
• Front radius arm to front axle bolts and bushes (four pairs in the worst case);
• Front panhard rod to front axle bolt and bush (one pair).
• Front anti roll bar to front axle link assemblies (two).
• Front tie rod ends (four in the worst case).

Transmission and brake oils

• You will need need some oils for the newly acquired front differential and for the newly acquired transfer case.
  • While you are at it, you should also change oils in the gear box and in the rear differential too.
• Since brake pipes will temporarily be disconnected from the front brakes, some air will probably enter the brake system.
  • Therefore, and air purge from the brake system will probably be necessary.
    • Why not change the entire brake fluid at the same occasion.
• Required oil specifications and quantities are written in the "Forecourt" wiki article.

Additional considerations regarding required parts

Propeller shaft mounting positions

• Beware that it is very important to mount every propeller shaft to the connecting devices (example: differential, transfer case, etc.) exactly as it was originally mounted.
  • Reason: every propeller shaft was balanced for that mounting position in the factory.
    • If it is mounted in a different position, it could cause vibrations while spinning.
• It is easy to preserve the original mounting positions for the middle and rear propeller shafts, as it is possible to mark them before disconnecting them from the dummy transfer case.
• However, the front propeller shaft has to be obtained from another vehicle, and its original mounting position can be lost.
  • Therefore, it is highly recommended to obtain the front differential, front propeller shaft and the transfer box all from the same donor vehicle.
    • Just don't forget to mark the position of the front propeller shaft in relation to the front differential and to the transfer case before demounting them from the donor vehicle!

Differential gearing ratios

• The gear ratio of the front differential has to be exactly the same as the ratio of the rear differential.
• One (less certain) way of achieving this is to get the parts from a donor 4WD Jimny vehicle which has G13BB engine, as those vehicles should have matching front differentials.
  • 4WD Jimnys with non-VVT M13A engines (made from 2001-2005) should also have matching front differentials, but this is not that much certain.
• The other (100% certain) method of achieving this is to measure the gearing ratio of the front differential from the donor vehicle and compare it to the measured gearing ratio of the factory rear differential in your 2WD-only Jimny.
  • If the gearing ratios are the same, then you have a match.

The wiki article "Differential information" might contain some useful info.

How to measure the gearing ratio of a differential:

• Manually turn the input side of the differential (side onto which the propeller shaft connects) a set number of times (for example 10 full turns) while keeping one output side of the differential jammed.
• Then count how many turns has the other (free) output side of the differential performed for the set number of turns of the input side.
  • The gearing ratio is then calculated by dividing the two numbers.
  • Example: By turning the input side 10 full turns, the output side has turned 38 turns.
    • This results in 3.8 gearing ratio for the differential.

ABS vs. non-ABS vehicles

• The front wheel hub assemblies (probably) differ for ABS and non-ABS Jimnys.
  • Therefore, if this statement is correct, you should check if your 2WD-only Jimny has ABS or not, and then find a corresponding donor 4WD Jimny.

• As far as it is known, 2WD-only Jimnys with ABS should not exist (in other words - all 2WD-only Jimnys should be non-ABS), but who knows!
• In the case that your 2WD-only Jimny really has ABS, you will need to add some wiring between the 4WD transfer box and the ABS computer (explained further below).
  • Reason: The operation of ABS brakes differs significantly in 4WD modes compared to ordinary 2WD mode, and the ABS computer needs to be aware whenever the transfer box is in one of 4WD modes.

Wheels and tyres

• If your 2WD-only Jimny has 175 / 80 / R15 tyres, you might want to change them to a more "standard" Jimny size.
• The factory tyre size for 4WD Jimnys is 205 / 70 / R15, but that tyre width is probably too wide for those wheels which currently bear 175 width tyres.
  • Vehicle's ground clearance increases by only 3-4 mm when changing from 175 / 80 / R15 tyre size to 205 / 70 / R15 tyre size.
• However, size 195 / 80 / R15 is considered a great tyre size for all-terrain use for 4WD Jimnys, and width 195 might even fit onto those narrower wheels.
  • Vehicle's ground clearance increases by signficant 16 mm when changing from 175 / 80 / R15 tyre size to 195 / 80 / R15 tyre size.
• Someone should report here if 195 width tyres actually fit onto those narrow wheels or not.
• If you decide on changing your wheels and/or tyres, you should change all five, and use all five.
• The wiki article "Tyre selection and usage - best practices" contains a lot of useful info on tyre sizes.

Retrofitment guide

Removing current transmission elements

First of all, raise the entire vehicle up in the air, or position it over a canal with the front end lifted on stands and rear wheels securely locked.

In order to maximize the chances of unscrewing (many) old stuck bolts:

• It is recommended to spray all the bolts which are to be unscrewed with a good anti sieze "WD40-alike" chemical, or a deep freeze effect chemical.
• This should be preferably done at least 12 hours before starting any work, to leave the time for the fluid to penetrate deep in the treads.
• Also, it is better if this is done in at least two iterations, first 24 hours before work, and the 2nd spraying 12 hours before work.

Dummy transfer case removal

1. Optional: drain the oil from the dummy transfer box (if it has any oil in it).
2. Mark the positions of both propeller shafts in relation to the casing of the dummy transfer box.
   • This refers to the rear propeller shaft between the transfer box and the rear differential, and the small propeller shaft between the gear box and the transfer box.
3. Put those marks on the new 4WD transfer box in the same spots on which you put them on the dummy transfer box.
4. Disconnect both propeller shafts from the dummy transfer box.
5. Dismount the dummy transfer box from the vehicle.
   • You will not need this transfer box any more.
     • It's best to donate it to a technical school so that pupils can study how economics influence engineering decisions.

Dummy front axle removal

1. Remove both front wheels.
2. Disconnect the brake pipes from the front brakes.
   • Try to immediately plug the brake pipes with something so that the least amount of brake fluid (which is highly corrosive) leaks out.
3. Optional: Dismount the front brake pads, discs and calipers from the wheel hub assembiles.
   • This step makes sense only if you intend to reuse the front brake components on the vehicle after fitting the new 4WD front axle assembly.
4. Put two stands below the front axle so that it rests on them.
5. Disconnect both tie rod ends from the front wheel hub assemblies;
6. Optional (if you want to separate the front wheel hub assemblies from the front axle):
   1. Dismount the steering knuckle swivel seals from the wheel hub assemblies (leave the seals hanging on the axle casing);
   2. Remove king pins from the front wheel hub assemblies.
   3. Remove the wheel hub assemblies from the axle;
   4. Remove the swivel seals from the axle casing;
   • • Note: You would to this only if you intend to reuse the parts from the wheel hub assembly, like the king pins, steering knuckle swivel seal, wheel bearing, etc.
     • Note: It is not recommended to reuse any of those parts except possibly for the king pins and the swivel seals (if they are in very good condition). Better buy hem new.
7. Disconnect both front shock absorbers from the front axle (leave them hanging on the vehicle);
8. Disconnect the panhard rod from the front axle;
9. Disconnect both anti roll bar links from the front axle;
10. Disconnect both radius arms from the front axle;
11. Disconnect both coil springs from the front axle;
12. Finally, the front axle assembly should now be completely disconnected from the vehicle.
    • Just lower it down and take it away.

• You will not need the front axle (+ front wheel hub) assembly any more, so you can donate it for example to a paramilitary group of your choice.
  • They can use it on a makeshift trailer for towing light artillery.

Assembling the 4WD front axle

If you did not obtain the front 4WD axle assembly in a complete state, or if you want to refurbish some of its parts before its installation (example: king pin bearings), then some of these wiki articles might be helpful:

• Axle mount repairs
• CV joint replacement
• Front brake pad change
• Front wheel bearing replacement
• King pin bearing change

Anyway, even if you did receive the front axle assembly in the complete state and in perfect condition, you will still need to perform the following:

1. Permanently block the vacuum pipe connections on the wheel hub assemblies (they are not needed and just allow ingress of contaminants);
2. Remove the vacuum locking wheel hub heads.
3. Then either convert them to fixed hub heads, or install manually operated free wheeling hub heads according to the wiki article "Manual or fixed front wheel hub heads".
   • Concentrate primarily on part 1 (solutions 1a through 1d) in that article, as the other parts of that huge article are not that important for this case.
4. Change the oil in the front differential after all work below is done.

Installing new 4WD transmission elements

Transfer box

1. In the cabin, cut out a hole in the floor carpet where the transmission lever is going to be.
2. Now cut a suitable hole in the floor panel in the same place where you cut the carpet hole.
   • The best way to determine the exact position of this hole is to measure its position in another "normal" 4WD Jimny which has the transmission lever.
3. Rust-proof the cut-out in the floor panel.
4. Mount the 4WD transfer box on the vehicle, with the transmission lever protruding in the cabin.
5. Dress the rubber gaiter around the transmission lever.
6. Connect the small propeller shaft from the gear box to the transfer box.
   • Don't forget to properly align the propeller shaft to the transfer box according to the marks which you had made before.
7. Connect the rear propeller shaft from the rear differential to the transfer box.
   • Don't forget to properly align the propeller shaft to the transfer box according to the marks which you had made before.
8. Fill the transfer box with suitable transmission oil.
9. Try the transmission lever with the vehicle turned off and see if it moves correctly.

Front axle assembly

• Note: It is assumed that the "front 4WD axle assembly" is already complete.
  • This means that the differential, half shafts, CV joints, and the front wheel hub assemblies are installed / connected to the axle casing.
  • Manual or fixed front wheel hub heads are also assumed to be installed on the front wheel hub assemblies.
• Note: It is also assumed that the front brake components are already installed on the wheel hub assemblies.

1. Bring the 4WD front axle assembly up to the front end of the vehicle and put it on two stands.
2. Drain the old oil from the front differential (as you keep on working around, the last bits of oil will leak out).
3. Connect both radius arms to the front axle;
4. Connect both front shock absorbers to the front axle;
5. Connect both coil springs to the front axle;
6. Connect both anti roll bar links to the front axle;
7. Connect the panhard rod to the front axle;
8. Connect both tie rod ends to the front wheel hub assemblies;
9. Connect the brake pipes to the front brake calipers;
10. Optional: Change the brake fluid and bleed all brake lines;
11. Mount the front wheels to the vehicle;
12. Fill the front differential with new oil;

Front propeller shaft

• Install the front propeller shaft between the front differential and the transfer case.
  • Don't forget to properly align the propeller shaft to the transfer box AND to the front differential, according to the marks which you had made before.

Final steps

• Lower the vehicle onto its wheels.
• Turn the vehicle on.
• Lock the front wheel hub heads.
• Engage 4WD-H or 4WD-L with the transmission lever.
• Drive away on a dusty road into the sunset.

Additional electrical fiddling

Indicator lamps in the instrument panel

• After performing all the conversion steps above, the 4WD system is now fully operational.
• The only missing function is that 4WD indicator lamps in the instrument panel will not turn on when the vehicle is in 4WD-H or 4WD-L mode, simply because there is no 4WD computer in the vehicle.
  • However, the 4WD system will function just fine without the indicators - you just have to mentally remember in which transmission mode you are in.
• If you really want to have working 4WD indicators in the instrument panel (assuming that the instrument panel in 2WD-only Jimnys actually has them - not checked in practice), it can be accomplished.
  • You need to connect some wires from the switch in the transfer box to the corresponding connectors in the instrument panel.
    • The exact steps regarding which connectors to connect to which wires etc. should be written by someone else - currently you will have to refer to the corresponding Suzuki's wiring diagram.

ABS control computer

• If your 2WD-only Jimny has ABS (most of them should not), you will also need to add wiring between the transfer box and the ABS control computer.
• The goal is to make a signal connection so that the transfer box constantly sends signal to the ABS computer in which transmission mode it is operating (2WD, 4WD or 4WD-H).
  • Reason: The operation of ABS brakes differs significantly when the vehicle is in one of 4WD transmission modes compared to ordinary 2WD transmission mode.
    • The exact steps regarding which connectors to connect to which wires etc. should be written by someone else - currently you will have to refer to the corresponding Suzuki's wiring diagram.

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Page last edited on 19/07/2018 by user Bosanek