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Rebuild of Warn 8274 Winch

I scored an older Warn 8274 8000lb winch for $200 and decided to completely strip and rebuild it.

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1 - This is what my $200 bought! Note the hacked wiring as the remote was lost. The cable was also missing.

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2 - Top view

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3 - Mine was an older model that uses the 4 basic "starter style" solenoids. I'm actually happy about this as it's very easy to understand the wiring (and hence jumper or bypass it if required)

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4 - The newer models (with the remote plug-in on the side of the solenoid pack cover as opposed to the front) use a different solenoid style and a different wiring scheme. I don't know if the starter solenoids will work in those.

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5 - As you can see - all the electrics needed a damn good cleaning. In fact - I decided to totally strip and clean the whole thing.

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6 - The motor mounts to the winch, and its own end cap is held on by, these 2 long screws

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8 - Here's the motor being separated from the gearbox housing

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9 - The motor housing comes off the armature

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10 - Here you can see the keyway in the armature that indexes with the drive gear in the next pic

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11 - Here's the key in the drive gear that indexes in the armature shaft

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12 - Here the end cap is off the motor. Note the little cut-out in the top left that indexes with the small nipple on the motor case

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13 - Inside the motor, end cap off. Showing the brushes. On the end of the case, on the left, is the little nipple that indexes the end cap.

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14 - Another view of the motor brushes

15 - The motor case and electrical lugs

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16 - Make sure you don't lose this little washer on the end of the armature

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17 - Inside the motor with the armature removed


18 - You can't quite make out the name on the motor in the pic, but interestingly it is not Warn! This is an original "earlier" motor.

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19 - This is the top of the gear housing to which the motor attaches. You can clearly see the sealed bearing. Mine appeared fine, so I left it as it was.

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20 - Here's the freespool clutch. The gear on the right side is the main drive gear, that you will recall from pic 11 above indexes directly on the motor armature. The black knob is what the operator uses to select power drive (in or out) or freespool......

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21 - In is the position for power drive. This allows power out as well as power in of the cable.

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22 - Out disengages the motor from the drivetrain, and allows the cable to be freespooled out. Many an 8274 owner will tell you that the clutch rarely works, and the reason is because of corrosion between the shaft and the housing.

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23 - Here is what the clutch looks like engaged for power operation

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24 - And this is what it looks like disengaged for freespool

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25 - Next is disassembly of the brake assembly. When you remove the snap ring, the outside disc falls off under spring pressure, and all the ball bearings fall out!

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26 - This is the outside brake disc, and the center ring with the little brake pucks of friction material.

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27 - This is the inner brake disc still on the shaft

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29 - Inner brake disc coming off the shaft.

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30 - Here the brake and brake pawl are removed

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31 - With the motor, brake, and clutch removed, you can separate the gearbox into two half's. There are 3 Allen head bolts with square nuts. 2 on the outside and ....

32 - one on the inside.

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33 - I used a pipe wrench to carefully lever the case halves apart, as the silicone sealer was old and set like concrete

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34 - Here's the top half of the gearbox removed

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35 - Here are the spur reduction gears in the bottom half of the gearbox

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36 - The next step in disassembly involves the lockplate shown here

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37 - To remove the drum, you just need to pull the lockplate up, so it disengages the drum assembly

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38 - But if you actually want to remove the gears from the case (I didn't - didn't see any need) you tilt it to the side.....

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39 - ...invert it (note the larger hole in the plate).......

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40 - ........then lower it so the larger hole is around the gear shaft, so that the shaft can be driven out (brass coloured round part)

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41 - Here is the drum separated from the gearbox


42 - This is the gearbox, you can see the splined drive that drives the drum.

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43 - On the drum you will see thethrust washer (blue arrow), seal (red arrow) and bushing (green arrow).

44 - This is the Warn Part number 8680 "Service Kit - Lower Housing". It includes a new thrust washer, new seal, new bushing, new bushing for the other end of the drum, and a faded instruction sheet.

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45 - Close up of the replacement parts. You can see the lip on the thrust washer, which must go on first, same as the seal. In other words, they both go on the shaft the way they are sitting in this pic

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46 - Like this. This is the thrust washer going on.


47 - I don't know what the hell chewed the snot out of the splines - perhaps the lockplate improperly seated? Hasn't affected operation, which is good.

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48 - Here's the brake assembly being rebuilt. I re-used all my parts.

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49 - I used a sticky synthetic grease to stick the ball bearings on

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50 - This was the trickiest part

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51 - As you have to keep all the balls in place.....

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52 - .....while sliding on the ring with the brake pucks. After this, you have to replace the outside wheel, and then compress the spring enough to install the snap ring. It's a bear.

53 - Here's the brake pawl

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54 - It has a spring inside

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55 - That hooks around outside.

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56 - Because, in the older models like mine, the solenoid bracket is the ground for the solenoids, I added a small additional ground cable from the bracket to the motor housing

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57 - Also, in the older motors, the entire motor ground used a ring terminal under the head of one of the long bolts. This seemed a little inadequate to me, so I welded a bolt to the case to use as a big ground lug.

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58 - Next two pics just show it all rebuilt and cleaned up

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59 - Looking much better!

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60 - Final testing on the bench before installation. Took a battery and booster cables. Positive goes from battery (+) to the top left solenoid lug. Negative goes from battery (-) to the negative lug I welded on (motor case)

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61 - Testing setup

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62 - Then take a small jumper from the 12v+ to the S terminal of the lower left solenoid (green wire) and the winch should power in.

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63 - Then take a small jumper from the 12v+ to the S terminal of the lower right solenoid (brown wire) and the winch should power out.

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64 - I drilled and tapped a small hole to use as an oil filling spot, so I could easily add a little oil if I noticed any leaks, without having to split the gearbox case again.

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65 - Just big enough for the tip of an oil can

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66 - Of course, I had to mod the front bumper quite a bit to take the big 8274. The mount is a piece of 3/8" 7"x4" angle

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67 - It's critical to mount the winch good and square, and I suck at laying out holes in precisions, so to give myself room to adjust, I hogged out the left side holes with a torch!

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68 - This was kind of an interesting comparison between "vertical up" and "vertical down" MIG welding. The weld on the left is vertical down - looks nicer, but is not the proper way. On the right is two passes with vertical up.

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69 - It looks pretty good in there.....and is just about to get used here!

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70 - Here's the extremely sexy in-cab winch control I made. It has a guarded switch for power on / off, and two spring loaded momentary switches - one for cable in, and one for cable out.

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71 - It's kind of clever how I reversed the two black control switches, so that they can be distinguished even without labels or in the dark.

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72 - Here the guard is raised and the master switch closed, providing 12v+ to the operating switches. To stop all winch operation, one need only close the cover, opening the switch.

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73 - Here's how it works: Fused 12V+ from battery comes in on #1.

When the cover is raised and the master switch closed, 12v+ flows along #2 to the first (winch cable in) switch.

If that first (winch in) switch remains un-activated, 12v+ flows to the last (winch cable out) switch along #3.

However, when the winch in switch is activated, 12v+ is cut off from the winch out switch. In this manner, the winch cannot be simultaneously powered in and out.

When the winch in switch is pressed, power flows to the appropriate solenoid (S terminal of lower left solenoid) along green wire #4.

When the winch out switch is pressed, power flows to the appropriate solenoid (S terminal of lower right solenoid) along brown wire #5.

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74 - Another look at the back. Check out the incredibly cool screw terminals on the aircraft covered switch!

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75 - Here are the controls installed in the center console.

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76 - Close up installed, winch off.

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77 - Close up, installed, guard up and power to winch controls.

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78 - When I got the whole thing done, it had cost me so little, I treated myself to 125' of Amsteel Blue UHMWPE "synthetic" rope.

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79 - Check out the craftsmanship in that splice. I got my rope from a large industrial | marine supplier in Dartmouth. They sell a lot of this stuff to the offshore industry.

Here are links to the Warn exploded diagrams and parts lists. There are 2 different diagrams, depending on your Serial number.

Serial numbers 337844 and down.
Serial numbers 344816 and up

As far as where to buy the parts - I simply called Warn's 1-800-543-9276 number and asked for the name and number of the nearest authorized service center. There is an excellent web page by Warn where you can download the parts diagrams and lists for any winch (you will need your serial number) , as well as locate dealers. It is: http://extranet.warn.com/internetApps/ReplacementParts.nsf/findpart?OpenForm&SRWinches

As far as what parts to replace on spec during a teardown and rebuild, if nothing looks worn, I would only replace the "service kit, lower housing" part number 8680 (all serial numbers). It includes 2 bushings, a seal, and thrust washer. These are the parts I installed in pics 43 to 47 above.

The winch is lubricated with 6oz of NON-DETERGENT 30wt motor oil



I received a lot of e-mails about how the winch is supposed to be wired, how it operates electrically, and how to test the motor and solenoids, so I've added this section to address those questions.

My nomenclature / naming conventions

Motor has 3 terminals, I have labelled from left to right A, B, and C.

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Motor case is grounded directly to (-) terminal of battery

I use the term "12v+ signal" to refer to the small current 12v+ that is transferred from the winch power input terminal, through the switch or remote, and back to the solenoids to activate them.

I use the term "12v+ power" to refer to the high current 12v+ that actually powers the winch.

Solenoids have 2 studs (the large threaded studs on the sides), and a small terminal, called the S terminal (some have 2 small terminals, but for our discussion, only the small "S" terminal is used). They are simple electronically activated switches. When you apply a 12v+ signal to the small S terminal, the switch inside closes, connecting the 2 large studs together. This understanding is key to testing and troubleshooting your winch. NOTE: Technically, this is true only for SPNO (single pole, normally open) solenoids, such as those used in older 8274's (with the 3 pin remote connector) Warn part number 2040, and Ford "round style" starter solenoids. Also note, the solenoids themselves ground through their cases, and in the case of the 8274 to the metal solenoid bracket, and through it to the motor housing itself. Make sure all these connections are clean and tight. For extra insurance, I added a small ground jumper from the solenoid bracket to the motor housing (ring terminal under the head of one of the long motor housing bolts), so I wouldn't have to rely on only the large hose clamps holding the solenoid bracket to the motor case for the solenoid ground.

Here is a solenoid:

Technical drawing Drawing Auto part Diagram Artwork

Warn solenoids (pn 2040 for old style and 28396 for new style)

You can test your solenoids as follows:

1)Remove solenoid.

2)Check to be sure the contact disc inside the solenoid is not stuck, Connect an ohm-meter between the 2 large studs, the meter should show an open circuit or infinite resistance reading.

3)Connect a jumper wire from the solenoid case to the (-) term of your battery.

4)Connect a jumper wire from the small solenoid "S" terminal to the (+) terminal of your battery.

5)You should hear the solenoid "click", it is now "energized" and the 2 studs are connected together.

6)Connect an ohm-meter across the 2 large studs while the solenoid is energized, the resistance should read 0 ohms.

7)Remove the jumpers from the solenoid.

8)With the ohm meter set at the lowest scale, connect the ohm meter leads to the "S" terminal and the solenoid case. The reading should be between 3.4 and 4.5 ohms. If you get a reading lower than 3.4 ohms, the solenoid has shorted windings. If a reading higher than 4.5 ohms is observed, the solenoid either has a bad internal winding connection or corrosion in the windings. This occurs if the solenoid has been on the vehicle for a long time.

Winch operation

While reading this description, refer to the close up of the 4 solenoids as they are mounted to the winch, as illustrated in the pic below .

I have labelled the solenoids 1,2,3,4. Note that they operate in diagonal pairs. I have indicated the brass permanent connections in red arrows. The yellow arrows indicate 12v+ power output from the solenoid pack to the winch motor.

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Note: 12v+ power enters the solenoid pack, directly from the battery (+) terminal, at either of the leftmost studs. Mine was the top stud, as indicated in the picture. There is a smaller wire that carries 12v+ signal to the remote hand held switch (small blue wire in pic). When the remote switch is activated to either power in, or power out, this 12v+ signal is routed to either the power in wire (light green in pic) or power out wire (brown in pic).

Let's examine each case in turn.

If you select the remote switch to power in, the 12v+ signal goes from the blue wire, through the switch, and back to the solenoids through the light green wire. This causes #3 solenoid to close, connecting it's 2 large terminals (studs). The 12v+ power that is present at the left stud, passes through the solenoid, and via the cable attached to the right stud of #3 solenoid to the motor terminal B. Because of the physical connection between #3 and #4 solenoid, power is also present at the left stud of #4 solenoid, but it does nothing as #4 solenoid remains open. Also, because of the small black wire connecting the small "S" terminals of #3 and #2 solenoids, when you select power in - 12v+ signal also travels to #2 solenoid, causing it to close. This causes the motors terminals A and C to be connected together. Therefore, to power the winch in, we supply 12v+ power to motor terminal B and connect motor terminals A and C together.

If you select the remote switch to power out, the 12v+ signal goes from the blue wire, through the switch, and back to the solenoids through the brown wire. This causes #4 solenoid to close, connecting it's 2 large terminals (studs). This causes the motors terminals B and C to be connected together. Also, because of the small dark green wire connecting the small "S" terminals of #4 and #1 solenoids, when you select power out - 12v+ signal also travels to #1 solenoid, causing it to close. The 12v+ power that is present at the left stud of #1 solenoid, through the physical connection between #1 and #2 solenoids, then via the cable attached to the left stud of #2 solenoid to the motor terminal A. Note that the power does not travel through #2 solenoid, as it remains open. Therefore, to power the winch out, we supply 12v+ power to motor terminal A and connect B and C together.

This description should allow you to test and troubleshoot your winch and solenoids. Also, you can "jumper" the winch motor in the field in an emergency situation (solenoid failure), using the following technique. Use jumper cables and a long screwdriver. Attach one end of + jumper cable to battery +, the other end to motor terminal C. Attach one - end of the jumper cable to battery - terminal, the other end to the winch motor case. Then using a long screwdriver with insulated handle, jumper motor C terminal to either A or B, depending if you want to power out, or power in.

Here is a schematic of the above description, using my labelling conventions:

Text Line Diagram Design Parallel


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