Underfloor / centre mounted PTO winch on LJ78 - Landcruiser II (1 Viewer)

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Write up of my lockdown project, putting a PTO driven winch underneath an LJ78. The winch goes into the rear, more or less underneath the rear seats and is front facing, meaning that I had to reverse the PTO output shaft as well as the winch gear itself. I'll post lots of photos for reference to make it easier for others tackling something similar. I already had an electrical winch upfront (Toyota Aisin 1000 original) but as it sometimes locks up under high load and I regularly participate in events where winches are a must have, I wanted to have something redundant. Project is all done but I am only now finding time to write it up - I'll be writing it up in stages so bear with me if not all complete.

First of all some credit to others: I followed build threads from kbushnz and andrewfarmer that had similar projects and I found very useful as reference points: PTO Winch install KZJ78 and Gertrude centre mounted PTO winch.

UNBOXING
Seafreighted from a seller in Malaysia without being able to inspect it beforehand due to COVID. Came with PTO gearbox and most of the driveshaft. No shifter bracket though, only a home made gear stick instead, so not as "complete" as the seller had told me.

All unpacked and on my work bench

Circled in red above is the PTO output that I would have to flip around to make the PTO gear rear facing to the winch. The PTO box has a blinded outlet on the other side of the shaft and it should be possible to reverse it with few modifications.

 

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PTO OUTPUT SHAFT REVERSAL
Since the winch is going into the back of the car, the output shaft of the PTO box needs to be reversed to point to the back. Quick video to show how the PTO gear box functions. This is the model with one direction only, i.e. PTO box engages on or off and spooling in or out is then achieved by either selecting forward gears for spooling in and reverse gear for spooling out. Some PTO boxes have two gear wheels which gives you the advantage to use forward gears when spooling out (much faster!). Not mine though.



MEASURING CLEARANCE BEFORE TEARDOWN
Measuring clearance between Box wall and driven gear engaged/disengaged mode. This is needed for the calculation of the spacer (see later post)

TEARDOWN Part1
Retainer clip removal

Gear and shaft slide out with light prying (careful not to damage O ring)

 

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TEARDOWN Part 2
Crown nut removed and tapping out output flange

Measuring clearance of shaft gear to PTO box side wall. Important measurement as after reversal of shaft this gear needs to sit in same position.

Forward Bearing cover removal (seal still on the housing on the photo). I marked the sides of the bearing cover and PTO housing to be able to put it back on in same orientation.

Rear facing bearing cover removal (again with seal showing on photo).

Rear facing bearing C clip. I removed this and thought about hammering the shaft out from the side (I don't have a bearing press). I decided to leave it in in the end - this was the right thing to do as after teardown I realized that this side of the bearing can stay on the shaft.

 

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PTO TEARDOWN Part 3
Rear facing seal removed (you can see the bearing lubrication channel).

Front Bearing C-clip removal. This C clip holds the shaft in position - the bearing has a press fit onto the shaft and the c-clip on the bearing itself is sandwiched between bearing cover and PTO housing, thus keeping the shaft (and the gear) in position. Once removed, the shaft assembly slides back and forth with massive play that is limited by the gear hitting the inside of the housing.

First attempt at removing the bearing. Sandwiched a piece of wood in between gear and housing and hammered from front of shaft. Used a socket to protect the front shaft thread.

Worked reasonably well and shaft was driven out to the rear. Photo below shows how much stick out the shaft still has once the bearing is off the race. Other way to drive the bearing off is to reinstall the c-clip and use that as a counter (against the housing) when hammering the shaft. I had to do this during a test fit later on in the build. Did not feel great (c-clip is only 1mm or so thick) but it held up in my case.

This is the shaft assembly sequence as it sits inside the PTO box. From right to left: Rear bearing, gear, thick spacer, and spacer washer.

 

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PTO SHAFT REVERSAL TRIAL INSTALL AND MEASUREMENT.

Shaft components individually, gear, thick spacer, thin spacer/washer

Original shaft components reversed to position gear in more or less same position relative to PTO housing: From right to left: bearing (untouched in original position), thick spacer, gear, thin spacer, front bearing (just for demo and not sitting on actual race yet). Note that the small spacer does not fit on the rear part of the shaft as it has a slightly smaller ID than the thick spacer.

Reinstalling shaft in reverse. Used the output flange to drive the bearing in (needed a bigger hammer though then the plastic mallet on the photo) and countered with a socket that sits against the shaft.

I found that the spacing of the gear was off and it was hitting the PTO housing at the front of the shaft. It needed to sit further away from the housing (closer to the rear bearing). After taking some measurements, the solution was to shorten the thick spacer by 3.3mm and to put an additional 3.7mm spacer in the front. Below is the sketch I made for the local machine shop. If I were to do it again, I would make the front (new) spacer 0.5mm thicker, as my gear teeth between the driven gear and the output shaft gear ended up being offset by about that much.

 

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INSTALL

Parts back from machine shop: shortened thick spacer and new (stainless steel) spacer.

Mock-up of assembly sequence: rear bearing, (shortened) thick spacer, gear, new spacer, older thin spacer/washer, front bearing.

Sliding the new spacer onto the shaft after pushed through the gear. You can see on this photo how without the spacer, the gear is touching the inside of the PTO housing.

Set-up to drive bearing on using sockets.

Shaft installed and photo showing spacing between gear and housing.

 

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INSTALL Part 2
Bearing driven on, c-clip installed and front bearing cover on (now facing rear of PTO). I used silicone sealant in addition to the old gaskets (new gaskets impossible to get hold of where I live).

Rear shaft bearing cover installed (now facing front)

Final assembly done. Output shaft now facing rear instead of front (PTO is in "engaged" position on photo).

For comparison, the "before" photo - PTO is in "disengaged" on this one.

 

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SHIFTER BRACKET FAB
So the winch came with a home-made gearstick but no shifter bracket. So next part of project was to fab one up.

Marking out where to cut an opening for the shifter (and then deciding to place it 1 inch to the right, the large hole). Will cut out the remainder once installed.

Found three mounting holes tat can be used as bracket attachment. Two on top and one on side. Photo shows the two on top of gearbox.

Early life of shifter shaft. Old M16 bolt. Plan is to make this shaft greasable. Took off the head, filed it down to close tolerance with shifter bushing and drilled a grease channel. I will be cutting off most of the shaft when welding it on to the bracket.

 

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Drilling out grease channel from the M10 thread I will be using for locking the shifter in place.

Next Step drilled and tapped an M8 thread for a grease nipple.

Thread portion cut of for welding onto the shaft.

Thread welded on and groove filed for better greasing. This was my beginner fab'ing project so the weld is not great (but holds). Mock fit up of shifter to shaft.

 

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Did not take any photos of fabbing the actual bracket itself but It is basically a strip of sheetmetal reused from the old exhaust heat shield, reinforced with thick DIY shelving brackets to give rigidity. Front and back view of final assembled bracket, pre paint job. The push rod that came with the DIY shifter was wrong length so I cut, shortened and re-welded as well. No comment on the weld quality, please

I figured out that I would need a remote camera with view of the drum, to check for winch line binding during pulls, so I added a small bracket and installed a motorcycle brake light switch. Photo is without the spring, which connects front he switch to a small tab I made on the shifter. The switch is wired into the reverse camera circuit of the radio.

 

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Some photos of final installed shifting bracket (note the 90 degree grease nipple to allow access from underneath). Switch also wired into radio circuit (not shown on photos). I used foam strips as makeshift sealing/deadening between cabin and shifter and will replace with some kind of rubber gator when I find the time/ donor part.

 

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REVERSING WINCH INPUT SHAFT
Since the winch will sit rear from the PTO box and still be front facing, the drive needs to be switched around from original set-up of "front facing, rear driven" to "front facing, front driven". Alternative would be to turn the winch upside down (lubrication issue) or flip it 180 degrees. The latter has two issues: 1) the shaft between PTO box and winch would have a large angle and 2) the spool direction relative to the PTO drive shaft would be inverted, i.e. forward gears would spool out and reverse would spool in (which can be fixed by spooling the winch rope from the bottom of the drum instead of from the top as designed). Luckily, Toyota makes it easy and the drive shaft flipping is an easy affair:

Bearing caps marked Front and Rear before removing.

Worm gear shaft and the two bearing cups removed. The shaft slides out once the caps are removed; bearings can stay on the shaft. The seal on the shaft cup was still in fairly good condition so I left it on (again, impossible to source where I live anyway). Clean up of seal surfaces before reassembly (and new gasket maker applied before reassembly).

Done. Shaft now front facing.

 

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PTO BOX INSTALL
Blind cover off, PTO box on. My gearbox already had the PTO gear installed inside the gearbox (possibly from PO), i.e. no further mod needed.

Blind Cover removed and found the gear box side PTO drive gear where it should be.

PTO gear box flanged on.

 

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U JOINT REPLACEMENT
Fresh spiders into the U-joints. C clip removed and then using sockets to drive and to counter, hammers out the old cups. One of the cups was rusted solid and had to be cut with a dremel. The U joint spiders measured 20.0 mm cup diameter by 57.0 mm across, cup end to cup end. Took this to the local parts store and they found some u-joints with same dimensions that fit a 1980's corolla drive shaft. Brand: GMB, Model GUT-11.

Old U-joint with C-clips on. All of the C-clips broke off still inside the yoke when I compressed them using C-clip pliers due to ~30 years of metal fatigue; I ended up needing to carefully pry the remainder bits out of the yoke with lots of WD-40 and a screwdriver. Managed to get the C-clips out without damaging the yokes.

Large socket underneath to drive the cup into and a small socket on top to push on the opposing cup. Needed some hard blows with the hammer to come out but eventually did.

Old spider and cups with bearing needles still inside compared to new spider (with cups on).

Pressing on of bearing cups with vice. Assembled U-joint with grease zerk. So pretty!

 

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INSTALL PREP - DETERMINING WINCH LOCATION

Built a wooden cradle to make lifting easier.

No way to get a straight line path to the font so will need to angle it slightly facing the left side (10-15 degrees) to clear the PTO box and use a pulley. Goal is to to max one direction change. Winch will attach to the cross member that holds the upper rear spring mounts. I used string for lowest centre and highest drum end location left/right to check clearance in all conditions.

Mock-up of direction change at on the transfer case cross member. Used a Snatch block for now. For the actual install, I ended up using a lifting eye attached to the 2nd chassis cross member.

Front exit. Due to the electric winch mounted up front, I need to stay low and come out somewhere just under the winch plate, off centre to the left from vehicle centre point. That way it clears oil pan, steering and sway bar.

 

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MOUNTING
The plan: rear mounts will be on the cross member that holds the upper shock mounts. Front mount will be fab'd from the original 8mm angle iron that came with the winch, attached to the left frame member on the left and on the right hand side welded to new straight piece of tubing running a 90 degree angle from the front cross member and the rear cross member. I'll be using 4mm thick 2x2 inch square tubing for the remainder bracing/mounts. Optionally, I will link the second and third cross member with additional bracing. Sketch below:

REAR MOUNTING
Rear bracket fab'd. Angles were a royal pain in the butt to deal with - due to the winch offset to the left, none of the tube angles were square. The other thing to watch out when determining location is to make sure that no clashes with the drive shaft on one side and the control arm on the other. Lot's of measuring, test-fitting, remeasuring involved. Used a 54mm hole saw to make the end cut-outs so that the cross member would sit nice and snug. The left cut-out was then contoured with an angle grinder a bit so it could fit snug to the upper spring dome plate. Total build time with welding to cross member was about three full days (I am a hobbyist with limited prior welding and had to learn as I went along).

Cross member prepped.

Bracket tacked on.

Fully welded and painted.

 

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MOUNTING SPACERS & FRONT BRACKET BUILD Part 1

2 x MOUNTING SPACERS
I may be later increasing the drum side walls to spool longer rope on, so the winch drum cannot sit flush to the cross mounts. for that, I built spacers using 3x 6mm flat bar. Photos shows one welded spacer just before drilling the mounting holes for the winch.

FRONT BRACKET RIGHT SIDE
Fab'ing of the piece that goes from odd angle 8mm bracket from winch to straight angle font cross member. In order to get the angles, I installed the winch alreadoy to the rear mounts (no photo taken)
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Prepping and tacking the piece to the 8mm original angle iron.

 

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FRONT BRACKET RIGHT SIDE CONT'D

Welded all around and closed the gap on the rear with a piece of 6mm bar.

FRONT BRACKET LEFT SIDE
The left side will be attached to the frame - to spread the load over a larger section of the frame, I fab'd a mounting plate from 10mm plate I got from the local machine shop for free. At that point in the build I was still undecided on whether to mount the plate with bolts and drill through the frame or weld on. Both have pro's and con's - In the end, I ended up welding onto the frame. Photos show card board mock-up measured underneath the car and transfer to plate. Note the curvature on the inside of the 8mm angle iron has and needs to be cut-out like that on the plate. This curvature result from the factory fillet weld.

 

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FRONT BRACKET LEFT SIDE CONT'D
10mm plate turned out to be too much for my jig saw and I don`t have a plasma cutter so it was a long process of drilling and contouring with a dremel wheel (angle grinder wheels were too big).

FRONT BRACKET TRIMMING
Last step was to cut off excess material on the left and right hand side of the 8mm angle iron and below shows the finished bracket (left side 10mm mounting plate slides freely back and forth and will be welded in position as last installation step).

 

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FRONT BRACKET INSTALL
Front cross member prepared for welding and straight piece 2x2 tubing piece welded between cross member and bracket

Second straight piece welded between rear cross member and front bracket. The reason for the angle corrections on the front bracket vertical tube piece is so that the load can travel in the connection pieces 90 degrees to their cross section, i.e. where they have most strength. Front connecting piece will be compression loaded, rear piece will be tensile loaded. The vertical offset between front and rear connecting pieces is not ideal from a load distribution perspective but unavoidable due to required clearance to the rear diff. This mounting arrangement also allows me to drop the winch for maintenance vertically without much fiddling and I still maintain full motion of the engagement lever. On this photo, you can also see one of the earlier mentioned fab'd spacers in between winch and front bracket.

Left side mounting tacked to frame before welding out (note that the plate has been angled off in the corners to minimize straight vertical welds).