Winch Repair & Rebuild

[maineSS]

The bushings will need machining both externally and internally to fit, and there are several ways of doing it, some a lot more accurate than others.
You will need to make accurate measurements of the internal and external diameters of bushings, shaft, and housings, preferably to .001". I used a micometer and snap guage, but you can get by with a good set of calipers.
Take 4 measurements 90 deg apart at each end and in the center of your bushing to check concentricity and taper. I found my bushings about 4 to 6 thou oversize on the outside, and 3-4 thou small on the inside. 4 thou on the outside is a real stiff press fit- I cut it down to 2 thou oversize. Keep in mind the interior dia will shrink about the same as the press fit.

My machinist had a special tool leftover from another job that proved very useful for bushing prep inside/outside, and even as a press tool! It's a 4" dia aluminum round bar turned down about 1/8" under the bushing dia, with the small end split 4 ways and tapped with i/2" NPT(pic #22). A 1/2" pipe plug forces the split apart to help grip the inside of the bushing. We used 2" sanding strip to make up the 1/8" dia difference, and to open up the bushing interior (pic#23). The rear was drilled and tapped for a 3/8" bolt, so it could be chucked up in a 1/2" drill and used on the case bushing after it was pressed in. A 2" dia bar would work as well to fabricate the tool, the 4" stock just happened to be handy when the previous job was done.

[maineSS]

A file proved to be the quickest way to bring the bushing OD down to a 2 thou oversize (pic #24). Measure each bushing and housing combo- they're not all the same, and you may find the bushing varies from end to end, as they're cast. After getting the outside to spec, we sanded the inside out by 2 thou by holding the bushing as the lathe turned at very low speed. The pipe plug in the end of the tool was turned in just enough to prevent the end from collapsing, but not enough to cause any taper. The tool was then used to start the bushing (pic #25 shows the leg housing). After all the bushings were installed in their respective housings, the first of many fit-ups began.

[maineSS]

A special modification was made to the case bushing. The OEM shaft had rusted in this area, due to water infiltration after the oil film ran out. I decided to try providing a grease "seal" in this area by cutting a 1/8" wide X 1/16" deep slot in the bushing, and fitting a 1/8" grease zerk to the case. The zerk was located 1/4" in from the end of the bushing.The oil slot goes almost to the end of the bushing, so the grease slot had to be soldered up where it intersected the oil slot (pic #26). The solder sanded down nicely with the brass (pic #27). We found out the hard way that the zerk thread was 1/4-20, NOT 1/8 NPT, so the case hole had to be bushed and redrilled. Check your zerk thread BEFORE drilling if you do this mod. If you use a plain bushing, you could machine a slot closer to the bushing end for an O-ring seal, which might be better. Careful work with a Dremel, or vertically cutting down the side of the bushing with a long shank burr held in the Mill would give an oil slot. Pic # 27 shows the present arrangement, I'd probably go the O-ring route if I do it over

[maineSS]

After you get your bushings suitably modified and pressed in place, you need to measure their installed ID and compare it with your shaft OD. The bushing will collapse inward to the same degree of press fit, so a 2 thou press fit will result in a 2 thou smaller bushing ID. A manufacturer would simply ream everything out to a standard dia at this point, since they have close control over shaft and bushing diameters, but you won't likely want to spring for a $300 ream that will be used 3 times. Also, you're likely to discover unique variations in shaft vs bushing dia since you're dealing with different vendors. What I did was to take out 2-3 thou of the original 4-6 thou undersize of my bushings before I pressed them into place. Remember to compare your bushing ID measurement with your shaft OD to get the correct measurement for YOUR particular material removal needs- they will vary!

Braden told me they used a 1 thou per inch of shaft dia for clearance in their bushing fitup, so the 1.75" drum shaft should have 1.75 thousandths clearance in the bushing. I found this too tight- the shaft bound up in the case when rotated, even without the worm gear in place. I ended up with a 2 thou average clearance and things worked fine. I used the special tool shown in pics 23-4- it was threaded in the rear for a 1/2" shaft, which got chucked up in a 1/2" drill. After running the tool with the sanding strip thru the bushings several times, I'd do a trial fitup. When it got to the point where the shaft would bind occasionally in certain areas, the machinist went looking for high spots (shiny areas) with a scraper (pic #28). When you arrive at this point, you don't want to make the low spots any lower. The same proceedure was used on the leg bushing. Finally, after innumerable fitups, the drum shaft ran without sticking. Next will be Bearings & Retainers.

[maineSS]

There are a couple of trouble spots in reconditioning the worm shaft bearings. The first is removing the bearing races from the retainers, and the second is setting the proper bearing preload.
Pic #29 shows the retainer in a vice prior to removing the bearing seal. The seal is easily removed and replaced with a suitable dia rod and a few hammer taps. The bearing race is quite difficult to remove by forcible methods, as access to the backside is very limited (pic #30). I initially tried freezing the race with a special cold spray, but it still required a lot of hammering with a mini-sledge on my mini cats-paw. You need to have the retainer held in a 6" or larger vice with the cats-paw alongside the lower half of the vice (pic #31). Hit the top of the cats-paw with a drift, and move around the race at 180 deg intervals. If you have access to welding equipment, the next post will show you a MUCH easier way....

[maineSS]

The easy way to remove the bearing race is to weld a number of beads onto it (Pic #32). The race almost fell out after cooldown- definitely the way to go here. The replacement race is NOT bottomed out in the retainer- just press it level with the topside. Replacement bearing number is 23100, race number is 23256.
I was interested to see whether it would be necessary to index the retainers to the gearcase to obtain a straight wormshaft axis relative to the Bull gear shaft, but they were machined accurately enough so that the wormshaft would be centrally located on both ends regardless of retainer orientation. You may wish to check this on your unit, as the machining is pre-CNC, and mistakes occasionally did happen.
Setting the bearing preload for wormshaft endplay is absolutely critical according to Braden, and their specs call for .007-.015 endplay. The retainers have two different thicknesses (.010/.020) of paper shim between the case and the retainer to accomplish this. You make up a shim pack on each retainer, asssemble the worm shaft and retainers into the case, draw the retainer bolts up to 30 lb/ft torque, and measure the back and forth play of the wormshaft with a mag base dial indicator.
I found that .010 endplay was unbelievably sloppy- you could push the worm shaft side to side and round in a spiral! I removed 1 .010 gasket, and ended up with about .001 endplay- too tight by Braden standards, but more acceptable to me. The M-37 TM 9-1808B manual recommends that "the wormshaft turn freely by hand with no perceptible endplay"- which is what I got after using 3 .020 gaskets on one retainer, and 3 .020 and 1 .010 gasket on the other. I also ended up using a mix of LU4 and MU2 gaskets, because I didn't order enough from VPW. You want at least 6 gaskets of each thickness for this exercise. The LU4 gasket holes had to be slotted to match the MU2 bolt pattern (Pic#33).

[maineSS]

Endplay continued..

Too much wormshaft endplay leads to oil seal leaks along with heating and worm/bull gear wear. Too little play will not allow enough room for thermal expansion of the worm, leading to bearing and retainer damage.
Braden's way involves:
(1) Dropping the winch driveshaft and retightening the retainer capscrews to 30 lb/ft torque.
(2) Setting up a mag-base dial indicator on the face of the rear bearing retainer with the probe squarely against the end of the wormshaft.
(3) Engage the winch drum, rotate firmly in one direction till it stops, then hold constant tension. Zero the indicator. Firmly rotate the drum in the other direction and hold contant tension. Note the reading on the indicator and compare it to spec (.007-.014").
(4) If too tight/loose, remove retainer cap(s) and add/remove shims and recheck endplay. You may have to drain the gear oil to obtain a balanced shim pack.
(5) Tighten capscrews to 30 lb/ft, refill winch with oil, and readjust the safety brake.
As I mentioned before, this gave me an .010" endplay, which was much too loose for my liking. I then used the M37 TM method, which involves just the wormshaft in the housing- (take the bull gear out). The Braden engineer I spoke to said he always sets them up at the tight end of their spec, but my shim selection wouldn't give me .007". I intend to use synthetic wormgear oil once break-in is complete, so experience will show if I'm too tight. Next will be setting up the safety brake- our last show & tell picture essay. After the safety brake I'll finish up with "What Do You Put In It?"- my distillation of hours of wormgear lubrication research.

[maineSS]

On to the Safety Brake. This is meant to assist the worm in holding a load, NOT to hold the load entirely by itself. It also damps overrun when you stop winching. The gearset does most of the work in holding a load, which is why Braden specifically warns against using a synthetic gear oil before a gearset is properly broken in.
Pic #34 shows how the brake band is oriented for the normal "underwind" pull. It's important that both holes in the housing face down/sideways to avoid having water collect inside and eventually run past the upper wormshaft seal into gear housing. My brake was setup with one of the holes facing up, and this is likely why my winch oil was half water.
Pic #35 shows how the band will look from the inside as you assemble it. The anchor bolt end of the band faces downward, and the adjustment end faces sideways. If you want "overwind" pull, the anchor bolt and adjustment end would still face down and sideways, respectively, but the housing would rotate 90 deg clockwise to the left (looking at pic #35).
There are a number of replacement bands out there. The OEM replacement now runs about $85 from Sam Winer Motors (home of the Golden Gears). Sid Beck sells a good repro, but the ends are metric- 6MM X 1.0. A 1/4 x 28 nut will thread on a ways- then jam. Don't force the nut if it seems to stick- you may have a metric thread! VPW presently sells a cheapo band they recommend as a source of replacement friction material for your backing plate (pic # 36)- try not to mangle your band when you take it off. The top band is VPW's, the bottom is the OEM.

[maineSS]

There is a definite order of assembly- do it right the first time, or you'll do it again and again.. One of the housing bolts has to go in BEFORE you insert the band (Pic #37). Sid Beck's band has a long adjustment stud end which is difficult to squeeze in, but you'll want to wait before trimming it until you know the length of the tension spring. If your spring is totally rusted out (like mine), you can get one from VPW, Beck, or your local hardware store. Pic # 38 shows VPW's huge replacement next to Beck's OEM. The OEM spring has 8 coils of .074" wire, ID is .280", OD is .433", and length is 1.1". If you go with the VPW spring, you'll need a washer on the end due to its large dia.
The brake drum has a key and a setscrew, and needs to be adjusted to ride inside the band. My hub ended out 1/8" past the end of the wormshaft to achieve this (Pic # 39).
Once you get your band spring length figured out, you can trim the adjustment stud to length. You want just enough tension on the band to keep the winch from freewheeling after you stop input power, but not enough to have it brake heavily during inward rotation. If the housing gets hot during inward rotation, try loosening it up slightly.
Before I get into the Winch Oil dissertation, I found I'd missed a couple points. I'll wrap them up next.

[maineSS]

Squaring up the Base

When I got my winch, I noticed it seemed to stick at a certain point, and would require noticeably increased effort to rotate past. When I looked at the old bushings, they seemed worn oblong. The reason can be seen in pic #40. When I straightened up both base angles on the press, I found that the front had a tapering gap at the Leg varying from .070" to .066". Pic #41 shows how far off the new bushing was when clamped up against the base. When I initially tightened up the outside bolt, the shaft was hard to turn, and tightening up the inside bolt locked it up to the point where I couldn't turn the wormshaft with a screwdriver inserted thru the shear pin hole.
I tried "custom bending" the base angle to accomodate the Leg offset, with zero success. A tapered shim was made of stainless to fit the gap, pic #41 shows it in place. Making the shim took a bit of setup work which I'll detail next. Stainless isn't easy to machine, but I wanted one that wouldn't rust out in a few years and leave one corner adrift under heavy loads.

[maineSS]

The machinist and I thought the .004" taper would be a simple matter of surface grinding- we were quite wrong. The heat generated curled the shim like a potato chip. It happened during the initial sizing from .072" thickness to .070". The shim stock was Super Glued to a steel block, clamped to get an even glue thickness, and allowed to dry overnight. We ended up prying the first attempt off, and starting over. The next attempt featured a 1/2" High Speed Steel end mill- brand new. The block with the shim was supported in Mill vice on blocks and milled down .002" in 1/2 thou passes (pic #44). Next, one end of the block was raised .004" with a wedge, then clamped down and the taper machined in 1/2 thou passes at a moderate feed. Pic #45 shows what stainless does to a new HSS cutter- use carbide if you can get it. When I clamped the new shim in place, the effort was worth it. Fortunately, clamping down all 4 mounting bolts produced no bind.

[maineSS]

winch shaft greasing

Our last photo essay will deal with winch shaft rustproofing. The drum has a large cavity which can collect moisture over time and allow the winch shaft to rust to the point where heroic measures with Porta-Power and Torch are required to get it off. The best way of preventing this is to fill the cavity with semifluid grease. There are two zerks on either end of the drum which allow filling of a small circumferential slot, but these don't access the drum interior.
If you're doing this singlehanded, you'll have to stand the assembled winch up on the gearcase end, and then block the drum so it's about 1/2 way off the shaft (pic #46). You'll need 3 tubes of grease and a grease gun with a flexible hose. Run the hose down to the end of the drum, and start pumping, moving around the shaft as you go (pic #47). A complete fill will take almost three tubes, and you'll have to remove blocking as the cavity fills up (pic #48). Finish by filling the two zerk cavities, and you're good for years. Do this AFTER checking the winch base/shaft alignment- if you have to shim, it's MUCH easier without the drum weight and bulk in your way (Don't ask me how I know this). I used John Deere Corn Head Grease in the drum- I had originally meant to use it in the gear case, but talking with the supplier and various lubricant engineers steered me away from that idea. Worm gear lubrication will wrap up this series, hopefully it will be a once-in-a-lifetime experience.

[maineSS]

What do you put in it?

Perhaps the best way to start this is to note three useful worm gear/lube sites, along with revealing what was NOT recommended for worm gear use.
Site #1 is www.qtcgears.com/Q410/QTC/Q410P440.htm -an excellent overview of worm gear tech and lubrication. Site #2 is [url]http://www.noria.com/learning_center/category_article.asp?articleid=1080&relatedbookgro up and Site#3 is http://www.noria.com/learning_center...relatedbookgro .
Now the gear speed/lube chart in site#1 suggest that a grease could be used in a worm gear, and I have a fishing reel worm gear that is grease lubricated. All of the major oil company lubrication engineers I spoke with (Mobil, Shell, Texaco, Exxon) strongly discouraged the idea. The two main objections were inadequate heat dissipation and lubricant channeling. One of the enginners said grease would be okay for a museum exhibit where interior corrosion protection and minimal seal leakage would be major concerns. The manufacturer of John Deere Corn Head Grease (Northland Products) told me they'd never tested it for worm gear use, and if I chose to use it that way, I was on my own. After considering all this learned opinion, I delegated my three tubes of JD grease to winch drum/shaft corrosion protection, and moved on to oil-bath lubrication.

Here is Braden's present recommendation for ambient temp & oil viscosity.

Tier A: -20 to 20 deg- AGMA Grade 3EP, Mobilgear 600XP 100 or equivalent.

Tier B: 0-50 deg- AGMA Grade 5EP, Mobilgear 600XP 220 or equivalent.

Tier C: 40-105 deg- AGMA Grade 7EP, Mobilgear 600XP 460 or equivalent.

Tier D: 90-130+ deg- AGMA Grade 8EP, Mobilgear 600XP 680 or equivalent.

The two important numbers here are the AGMA (American Gear Manufacturers Association) and the ISO (International Standards Organization) viscosity rating (100, 220, etc). The "EP" means Extreme Pressure additives are present, and you have to be very careful about these around brass/bronze. There is another gear lube rating- the SAE system. Many people use an automotive rear end oil instead of the correct worm gear oil- not always a good idea! The following web sites have tables that relate the three viscosity systems- www.synlube.com/images/viscosity_table_2.jpg and www.bobistheoilguy.com/visc.html . I strongly suggest you print out one of these tables for reference- it will help your product comparisons considerably!

[Desoto61]

Excellent writeup, I had disassembled mine just before I went out of town, so I'll definitally be referencing this as I start my rebuild. Luckily mine was lightly used so I should be OK with just a refresh and re-assembly.

A tapered shim was made of stainless to fit the gap, pic #41 shows it in place. Making the shim took a bit of setup work which I'll detail next.

Could you have machined or ground the end of the drum support to get rid of the taper and then just used a flat piece of shim stock cut to fit to fill the gap?

[maineSS]

It looked like the case side was responsible for the taper at the leg, and the amount of taper varied depending on whether one case end bolt or two were tightend up. At the time, tapering the shim seemed the quickest way out (before we found that surface grinding thin stainless didn't work too well).