How much does track width increase when fully floating axle conversion is fitted?

Ok, there's a whole different set of problems there. As discussed, you can just full float convert your Jimny rear axle and call it good. It will need to be trussed to as close to the bearing pockets as possible. (I assume this this in some sort of competition/heavy off road use - out of interest, what tyre size?)

The Jimny front axle is a pain because it commits you to a Jimny third member so you have little choice of diff ratio. (4.09/4.3) because of the high pinion. It's completely possible to run SJ front knuckles and a panhard rod - I have for many years and a quite a few of us locally have set their cars up this way. Note, the Jimny front housing is very prone to bending too- the housing flexes during articulation in a stock Jimny application.

Here is my front axle. It's based on a Vitara rear housing cut down, heavily trussed and shaved. It runs SJ knuckles and a panhard rod. I also ran a WT SJ70 front axle with a panhard with no issues for many years set up with radius arms - this is now 3 link. The panhard is Range Rover. Axle is stock WT SJ width and runs cromo CVs and inner axles.









I ran a full float converted Vitara rear for many years but my car is heavy and I drive stupid stuff so I was breaking far too many rear axles. I have since swapped to 60 series landcruiser spindles and hubs and broached the airlocker side gears out to 30 spline. This still had almost no impact on track width. (~10mm - the width of the spindle flange)

I know this is miles beyond your original question but I've been messing with full float stuff for ~15 years on Suzukis. Vitara housings and thirds are cheap, and they have a huge range of ratios. Custom axles are expensive. breaking custom axles is a massive pain. Likewise, bending housings is a pain, as is straightening them. I'd recommend doing the work once.

My 30 spline conversion cost a bit of coin in machining the spindles to nest into the vitara bearing pockets in the and hubs to retain the 5 on 5.5" PCD and retain SJ front brakes, along with broaching the side gears, however now I have off-the-shelf Nitro Gear cut to length 60 series axles and I don't believe I'll ever be able to break them. That's a nice feeling. I never felt that way with 26 spline floater rear axles and I have a pile of broken axles under my bench to prove it.

Just some stuff to consider.

Gwagensteve said:

Ok, there's a whole different set of problems there. As discussed, you can just full float convert your Jimny rear axle and call it good. It will need to be trussed to as close to the bearing pockets as possible. (I assume this this in some sort of competition/heavy off road use - out of interest, what tyre size?)

The Jimny front axle is a pain because it commits you to a Jimny third member so you have little choice of diff ratio. (4.09/4.3) because of the high pinion. It's completely possible to run SJ front knuckles and a panhard rod - I have for many years and a quite a few of us locally have set their cars up this way. Note, the Jimny front housing is very prone to bending too- the housing flexes during articulation in a stock Jimny application.

Here is my front axle. It's based on a Vitara rear housing cut down, heavily trussed and shaved. It runs SJ knuckles and a panhard rod. I also ran a WT SJ70 front axle with a panhard with no issues for many years set up with radius arms - this is now 3 link. The panhard is Range Rover. Axle is stock WT SJ width and runs cromo CVs and inner axles.

I ran a full float converted Vitara rear for many years but my car is heavy and I drive stupid stuff so I was breaking far too many rear axles. I have since swapped to 60 series landcruiser spindles and hubs and broached the airlocker side gears out to 30 spline. This still had almost no impact on track width. (~10mm - the width of the spindle flange)

I know this is miles beyond your original question but I've been messing with full float stuff for ~15 years on Suzukis. Vitara housings and thirds are cheap, and they have a huge range of ratios. Custom axles are expensive. breaking custom axles is a massive pain. Likewise, bending housings is a pain, as is straightening them. I'd recommend doing the work once.

My 30 spline conversion cost a bit of coin in machining the spindles to nest into the vitara bearing pockets in the and hubs to retain the 5 on 5.5" PCD and retain SJ front brakes, along with broaching the side gears, however now I have off-the-shelf Nitro Gear cut to length 60 series axles and I don't believe I'll ever be able to break them. That's a nice feeling. I never felt that way with 26 spline floater rear axles and I have a pile of broken axles under my bench to prove it.

Just some stuff to consider.

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That is a lot of very useful info. Can I ask where abouts are you located?

My build is a rock crawler. The design is compliant for trials (UK AWDC rules). The wheels/tyres I have are 29" but I could go up. The plan was for 31" max as it's a small buggy.

I tried everything to make the panhard fit with SJ axles. I couldn't move the axle back any further to make space due to the sump and a desire to keep to the original SJ chassis layout as much as possible (though I've now had to make so many mods to the chassis that I'm wondering why I ever bothered keeping it). I have a 3" dropped pitman which decreased the space.

Changing back to SJ axles is definitely on the cards, but the plan was to take the easy way out to get the buggy moving first. I managed to fit the Jimny hubs to the SJ axle but then the steering link wouldn't clear the 3rd member. The angle of the 3rd member needs adjusting anyway to keep the front propshaft / drive axle in proper bridge configuration and once this is done then the steering link will clear the 3rd member. IIRC I will need to make custom shafts though.

Do you remember what the cost of your custom shafts was? They are not difficult to make, I think you're in the UK where Rockwatt used to make them at a decent price but unfortunately I fell out with him after he messed up a few of my projects and then wouldn't return my parts on the last project.

I'm located in Melbourne, Australia. Not all of this is relevant for a trials/crawling car, but as your retaining an SJ chassis, I'll run you through my packaging and some of my solutions.

You shouldn't need to go full float to run 31" tyres, especially if you car is light*. Keep rim offset as low as possible and run light tyres and I can see the need for the complication and cost of a floater. Whilst we only have minimal rock locally, our cars are generally pretty heavy - much heavier than a buggy - and our changeover point to justify going full float is 34". In summer we have pretty high traction conditions.

* how light it light? Most people massively underestimate how heavy their car is. Most SJ's wth modifications, ready to roll with a light load of tools and recovery gear, driver and passenger are on their GVM of 1350kg.

Your drop pitman arm will make packaging a panhard rod and keeping it in phase basically impossible. I run a Vitara steering box and pitman arm, which is nearly flat. As you can see in the photos, that allows the chassis end of the panhard to be hard up against the chassis, which makes it possible to keep it in phase even though the axle end is above the tie rod.

There is no need for a drop pitman arm with a panhard rod - the panhard rod sets the roll centre and you need to follow it with the drag link, unlike with a tall leaf spring lift where you need to try and lower the drag link to keep the roll centre and drag link aligned to prevent bump steer. I've tried to run the front roll centre as high as possible but there are physical constraints set by the drag link. My car runs no spring lift (compared to a stock leaf sprung SJ) and my bumpstops are roughly in the stock position relative to the axles, although they are inboard. My front axle is ~1.5" forward over stock. I picked this location so I have a chance of keeping headlight buckets and front guards.



For reference, here is my car at ride height. wheelbase is 100", track width is stock WT SJ. I'm running a 2" body lift and as mentioned, no spring lift. tyres are 35". I have just over 2" of front compression travel and 3.5" of rear compression travel. Rear bumpstops are flush with the underside of the chassis, so about 0.5" closer to the chassis than stock. I can't make it any lower. Rear is double triangulated 4 link, front is three link + panhard.

I have notched the sump for panhard clearance. No big deal (unless, perhaps, you are running a coil pack engine with a crank angle sensor)



General suspension configuration photos here:



Rear link location before I started re fabricating the rear of the chassis.



Front third link location during mockup. from control arms are cut down range rover front radius arms, retained from when the front was radius arm.



third link required the use of a Baleno exhaust manifold and relocated engine mount to get enough link separation.



I'm very confused about rotating the SJ pinion up far enough up to clear the Jimny tie rod. " to keep the driveline angles in bridge configuration" - in stock form the pinion points DOWN towards the transfer and the front output points UP at roughly equal angles. This is sound practice. Rotating the pinion up dramatically would require the transfer to be rotated dramatically up (or down) at the front output to keep the uni angles equal, and rotating the pinion up so dramatically will put it hard into the bell housing/sump area at full compression. If it's for rock crawling perfect angles aren't required in any case, certainly not worth the compromise on compression travel/ride height.

I've had to clearance my bell housing for driveshaft clearance as it is, that's with my pinion rotated down an additional 3˚ due to increased caster. I'm running an AW-4 automatic, but nonetheless there's precious little room around there. (photo is at full bump - i.e springs removed)



I've run axleshafts from three different suppliers, Typical cost was around £225 each. (aud$400) I've tried EN-26, 300M and Hy-Tuf. I could not prevent failure if the sidewall of the tyre was flat on the ground. Every full float shaft was broken with the car stationary and revs ~1500rpm - just straight out traction on the ground and torque multiplication. I reached the end of the road wth 26 spline. also struggled to find a supplier that could make axles properly - few are willing to spend the time to machine the diameter of the axle down to less than the base of the spline as per a factory axle, as a result, mine were consistently failing at the spline. My car runs 35" tyres, weighs ~1600kg loaded and with driver/passenger and has 100:1 gearing with an auto, so it can develop a lot of traction by Suzuki standards. It's not used for competition though.

I've also put the car on a huge diet, especially in the rear, and significantly reduced tyre and wheel weight. I also tried taller diff ratios to reduce torque at the wheels (4.65 vs 5.12) but the 4.65 gears are weak and I broke teeth on the front. Many of us are now running SXS race tyres to get more appropriate compounds and carcass weight for the weight of our vehicles. I'm running 35" Maxxis Roxzilla stickies. They're very impressive. I've had to go up to 10psi in the front tyres because they're so flexible they just folded up at the "normal" 5psi I used to run my 35" Krawlers at.


* For my American friends, I'm using the English/Australian spelling of "tires" as the OP is in the UK, likewise I'm using Vitara and SJ which are the UK conventions rather than Tracker and Samurai.

That is seriously useful information!

I'm trying to avoid cutting off the rear of my chassis but it's interfering with my shocks. Widening the track may give me just enough clearance to keep the stock rear of the chassis, which is why I thought about doing the full float conversion.

I forgot to think about roll centre :/ though I did work in the anti dive, anti squat, castor etc. I used the pitman lowering arm to keep the drag link horizontal and reduce bump steer. The panhard and drag link ARE in sync, they have the same length and angle. I'll need to decide if I want to change this now. Everything is cut and tack welded at the moment.

What is WT ? Not familiar with this.

Gwagensteve said:

in stock form the pinion points DOWN towards the transfer and the front output points UP at roughly equal angles.

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This build has been so slow that I've forgotten what the stock configuration was. So it sounds like it was in Z config. I've kept the rear drive shaft correctly configured in Z, but the front has fallen out of config. This can be sorted later when I build a custom axle, I can cut the axle and rotate the 3rd member as needed.

I keep thinking that I should post a build thread. I've taken photos as I've gone.

PS. Just a small terminology technicality: GVM is the vehicles gross weight carrying capability. Eg my Isuzu truck is 3.5 t GVM, it weights 2.2 t, so can carry 1.3 t (those aren't real numbers, they are for example only). What you're referring to as 1350kg is the kerb weight.

I'm trying to avoid cutting off the rear of my chassis but it's interfering with my shocks. Widening the track may give me just enough clearance to keep the stock rear of the chassis, which is why I thought about doing the full float conversion.

Click to expand...

I couldn't avoid this, even with a very high rear roll centre (by road driven car standards) I had quite a few goes at it and even with Bilstein shocks (small body diameter) I didn't end up with enough of the chassis left after notching it for shock clearance.

The other issue with leaving the chassis stock width is the springs end up inside of the rails, which makes it hard to maintain acceptable roll stiffness. My goal was to have acceptable roll stiffness without using swaybars because that's just something else to package. All up, it ended up much easier and cleaner to re fabricate the rear 1/2.



here is a poor photo of the rear shock mount I made up with the stock chassis rails. Basically only the inner face of the chassis rail remained. The axle end shock mount was (is) as far outboard as possible - it's almost inside the wheel. It was all a mess really - the chassis lost too much strength and distorted through welding. It was time to start over.



This was the solution. One of my 5150 Bilsteins broke using fabrication and as they are discontinued, I started looking for alternatives. A set of 12" travel 2.5" King smoothies popped up at the right price which I had NO chance of fitting out board, so it was time to bite the bullet and build the chassis around the idea shock and spring location.



Packaging is always very difficult and as we use our cars for extended drives in the forest where we need recovery gear, tools, water, food etc with us, I needed to retain as much cargo room as possible.



It's hard to get an overall view of the rear end arrangement but this is about as good as I have.

I can't advocate enough getting the shocks and springs where they need to be and then building the chassis around them. The improvement in suspension behaviour is so worth it. My car is so stable and balanced as a result.