Rebuilding the HE-120 Redrive Rick Cavallaro Disclaimer: I am NOT an expert mechanic. If something looks or sounds wrong in these directions, it probably is. I d be happy to receive any tips or feedback on how to improve this ( wired.cav@gmail.com ) Special tools needed: Circlip pliers Blind bearing puller ( http://www.harborfreight.com/blind-hole-bearingpuller-95987.html See Fig. 1) Spanner and pinion holder (homemade see Fig. 2) Arbor press (bench vice or drill press may suffice) Figure 1: Blind bearing puller - $40 from Harbor Freight Tools
Figure 2: Homemade spanner and pinion holding tool.
Bearings and seals Output shaft bearing: Bearing: 6003 C3 I.D. 17mm; O.D. 35mm; Width: 10mm - open - no shields Available from: www.vxb.com 6003 Nachi Bearing Open C3 Japan 17x35x10 Ball Bearings Code: Kit9805 Price: $5.88 Output shaft pilot bearing: Bearing: 6002 C3 I.D. 15mm; O.D. 32mm; Width: 9mm - open - no shields Available from: www.vxb.com 6002 Nachi Bearing Open C3 Japan 15x32x9 Ball Bearings Code: Kit9804 Price: $4.88 Pinion gear bearing: Bearing: 6003 RSR I.D. 17mm; O.D. 35mm; Width: 10mm Available from: www.vxb.com 6003-2NSE Nachi Bearing 17x35x10 Sealed C3 Japan Ball Bearings Code: Kit9678 Price: $7.88 Pinion gear pilot bearing: Bearing: 6000 C3 I.D. 10mm; O.D. 26mm; Width: 8mm - open - no shields Available from: www.vxb.com 6000 Nachi Bearing Open C3 Japan 10x26x8 Ball Bearings Code: Kit9802 Price: $4.88 Output shaft seal: Sorry I didn t note the specs for these. Pinion shaft seal: These either
Disassembly of the HE-120 Redrive Remove the three nyloc nuts that mount theredrive to the engine. You may want to leave the propeller on at this stage as it will make it easy to keep the output shaft from turning when removing the clutch bell. Alternatively, you can use the homemade pinion holder (figure 2) to keep the pinion from turning at that step. Remove the unit from the engine. Using the homemade spanner to remove the clutch bell (Figure 3). The clutch bell unthreads from the pinion with a counter-clockwise torque.
Figure 3: Removing the clutch bell using the homemade tools. Once the clutch bell has been removed you can remove the prop (if you haven t done so already). Remove the bolt that threads into the output shaft and holds the prop mounting plate in place. Remove the prop mounting plate. Mine was on there TIGHT. Using a torch to heat the aluminum mounting plate will make it come off much more easily. It s probably best to assume that heat will destroy bearings and oil seals but all should be replaced in any case. Loosen the six bolts that hold the two halves of the case together. Back them out a quarter inch or so. Holding the case from the output shaft side, use a rubber mallet to tap on these bolts to separate the two halves. The two halves are being held together by the pinion and output shafts that are seated in the bearings. Mine did not come apart easily. You can see some pry marks on my case halves because I tried every way of separating the two halves. If anyone has ideas on how better to separate the two halves I d love to hear it ( wired.cav@gmail.com ) Press the output shaft out of the bearing that s seated in the front half of the case and remove the output gear. Remove the output shaft oils seal. This should push out without too much trouble from the bearing side. I used a small screwdriver to do this. Heat the case with a torch and remove the output shaft bearing. It should come out reasonably easily with heat. Alternatively you could most likely press it out with an arbor press. Remove the pilot bearing that supports the opposite side of the output gear. I tried everything here as well. The ONLY thing that worked for me (and it worked like a dream) was a blind bearing puller (Figure 1). You can get one of these for $40 from Harbor Freight Tools and it s worth every cent (http://www.harborfreight.com/blind-holebearing-puller-95987.html )
From the clutch bell side, press the pinion gear out of the bearing that supports it. This is best done with an arbor press. I did it on my drill press. From the pinion gear side push out the oil seal toward the clutch bell side. Using circlip pliers remove the circlip on the clutch bell side. This holds the pinion bearing in place (figure 4). Figure 4: Circlip retainer holds the pinion shaft bearing in place Press the pinion bearing out toward the clutch bell side. Again, and arbor press is probably the right tool (and again I used my drill press).
Using the blind bearing puller (figure 1), remove the pinion gear pilot bearing from the other half of the case. I found it best to mount the case to a large piece of wood when using the bearing puller. Re-Assembly of the HE-120 Redrive Press the new bearing onto the shaft of the pinion gear (Fig 5). I did this with a standard bench vise. You should really use an arbor press. Note: I used a socket between the vise jaw and the inner bearing race, and a piece of plastic between the pinion shaft and the opposite jaw. The socket insures that no force is taken by the balls between the two races. We want to put pressure on the inner race to press the inner race onto the pinion shaft. We don t care about the old bearings, but we want to treat the new ones right when installing. I also chose not to use any heat when installing the new bearings. I didn t want to cook the grease in the bearings or melt the oil seals. Figure 5: Pressing the pinion gear into the new bearing
Go slowly and make sure the bearing is going on straight. If you see a slight misalignment, correct it right away. Don t force the bearing on with any misalignment. Press the bearing and pinion into the case (figures 6 and 7). I put the assembly on a piece of wood directly over a hole that would allow the pinion to extend downward as the bearing was set. Figure 6: Pinion and new bearing partially pressed into the case To set this bearing I used a larger socket to ensure that all the force is placed on the outer race as that race is pressed into the case (figure 7). In this case I tapped it in with a hammer, again making sure to keep the bearing aligned at all times. Again, you would probably be better off with an arbor press.
Figure 7: Using socket to insure force is applied to outer race only Once the bearing is seated well in the case, replace the circlip retainer using a pair of circlip pliers (figure 4). Be careful to insure the circlip is well seated in the groove all way around (figure 8).
Figure 8: Fully seated circlip retaining pinion shaft bearing
Figure 9: Inserting output shaft pilot bearing Turn the case over and insert the pilot bearing for the output shaft (figure 9 and 10). Again, I used a large socket to engage the outer race only and again tapped it in with a hammer.
Figure 10: Pilot bearing seated in case
Figure 11: Clutch bell oil seal re-installed Re-install the bearing seal where the clutch bell will go. I put a film of oil on the inner and outer seal surfaces before installing the seal by hand. It just seemed like a good idea. Thread the clutch bell back on the pinion shaft (figure 12 & 13). Clockwise to tighten.
Figure 12: Re-installing the clutch bell
Figure 13: Clutch bell threaded onto pinion shaft finger tight Insert the output gear into its bearing and then use the homemade tools to prevent the pinion from turning while you turn the clutch bell clockwise to tighten it firmly onto the pinion shaft (figure 14).
Figure 14: Tightening (or loosening) the clutch bell using home made tools Figure 14 shows the homemade pinion holding tool. Note, this piece of hardwood has two holes to accommodate both the main gear and pinion gear shafts. It also has 6 bolts that engage the main gear to keep it from turning while the clutch bell is being tightened with the homemade spanner. Press the output shaft bearing into the case (figures 15 & 16). In this case I used a socket to insure the force was carried only by the outer race, and pressed it in with my bench vice. As always, I m sure an arbor press is a better choice.
Figure 15: Setting the output shaft gear in place to be pressed in.
Figure 16: Pressing the output shaft bearing into the case Re-seat the main gear in its pilot bearing in the case so that it properly engages the pinion gear. Press it fully into the bearing with an arbor press. Put the rubber O-ring gasket in place before putting the two halves of the case back together. Place the front half of the case over the output shaft. Line it up and press it on by hand as far as possible. Put a socket over the output shaft so it presses on the inner race of the bearing. Press the case on over the output shaft using an arbor press (putting the force on the socket). Put the six screws back in that hold the two halves of the case together. The two longer screws go to either side of the shaft. The four in the corners are slightly shorter. Put the new oil seal over the output shaft and seat it in the case. This can be done fairly easily by hand.
Insert the woodruff key into the output shaft and then carefully place the prop mounting plate on the shaft so that it aligns with the key. Press the prop mounting plate onto the shaft until it s fully seated. I chose not to heat the mounting plate because I didn t want to damage the oil seal. It doesn t slide on easily. Alignment is everything. Once it s clearly engaged over the key, I use the bolt that holds it in place to pull it down until it seats. I figured this has the advantage that it places no axial force on the bearings. To keep the shaft from turning while I tighten the screw, I place a screwdriver through one of the holes in the case and one of the holes in the clutch bell. I did this without the lock-washer, and then backed the screw out, added Loctite and put it back in with the lock-washer in place. With both the top vent and side plug removed, put 55 cc s of gear oil in the case. This should fill the case right up to the side plug hole. It should be easy enough to check the oil level and quality every so often by removing both the top vent and side plug, and tipping the whole unit a bit to one side to get a bit of oil on your finger. If you have to tip the unit more than a few degrees to get a bit of oil out, your oil is low.