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How do you disassemble a belt reduction unit
- Thread starter calndux
- Start date
Assuming its a Franklin unit, it takes a bit of dexterity to get to all the bolts but its not hard just tedious. The below applies only to the Franklin CH-2/CH-3 units. I have no knowledge of any other belt drives. This is how I learned to do it in the fleet shop we ran in the seismic world.
1. Disconnect battery.
2. Remove flex plate bolts and save spacers, they arent washers. You can either pull the prop around to get to them or use a crowbar in the flex plate starter ring.
3. Remove prop.
4. Remove all the bolts for the top drum, rotate the drum to losen the belt, and lift the drum out. This removes the belt (from the top drum only) in teh process.
5. NOW put something under the redrive that will hold it up and something under the engine to hold it up as well. Make sure both are sturdy and steady.
6. Remove the bolts that hold the belt drive to the bell houseing mounts on the block.
7. At this point the engine and the redrive now have NO connection. Remove the redrive engine stand bolts and lift out the rubber bushings. Lift the redrive housing off the engine and away from the boat. The belt will come with it. Remember there is NO rear mount on the engine at this time.
If you needed the above then you might want this as well.
To remove the lower bearing, I have never seen an arbor press successfully take one out. I have seen 2 broken with an arbor press. We used a LARGE rosebud and heated the aluminum casting evenly all around the bearing. When its hot enough to expand the bearing will simply drop out of the casting like ya dropped a rock on the floor. There will be a lot of fire and flame as the grease burns in the bearing. It takes quite a while to do this. Do not beat on the bearing or casting. Do NOT cool the casting, let it cool naturally, this includes not blowing a fan on it to cool it. The loop that holds the bearing can be broken very easily so let it be til ya can put your hand on it and it doesnt feel hot. NOTE: Do not pick up the old bearing with your hands intil it is cool, it will set YOU on fire LOL !
You can seat the new bearing with an arbor press but make darned sure the seat is clean and the new race is clean. Make sure everything is level before ya put any pressure on it. Use the proper matching rings etc. ( do not just use random pieces of stock laying around the shop, use a full ring ) to elevate all the parts then a ring only on the seat set it gently and perfectly square. No pressure on the inside race or bearings. Once set remember to grease the hell out of it.
If anyone else can add anything to this or a better or even just different way you have found, please let us all benefit from you'r knowledge. Especially the lower bearing removal and installation. This is a super easy place to damage a Franklin unit.
Scotty
1. Disconnect battery.
2. Remove flex plate bolts and save spacers, they arent washers. You can either pull the prop around to get to them or use a crowbar in the flex plate starter ring.
3. Remove prop.
4. Remove all the bolts for the top drum, rotate the drum to losen the belt, and lift the drum out. This removes the belt (from the top drum only) in teh process.
5. NOW put something under the redrive that will hold it up and something under the engine to hold it up as well. Make sure both are sturdy and steady.
6. Remove the bolts that hold the belt drive to the bell houseing mounts on the block.
7. At this point the engine and the redrive now have NO connection. Remove the redrive engine stand bolts and lift out the rubber bushings. Lift the redrive housing off the engine and away from the boat. The belt will come with it. Remember there is NO rear mount on the engine at this time.
If you needed the above then you might want this as well.
To remove the lower bearing, I have never seen an arbor press successfully take one out. I have seen 2 broken with an arbor press. We used a LARGE rosebud and heated the aluminum casting evenly all around the bearing. When its hot enough to expand the bearing will simply drop out of the casting like ya dropped a rock on the floor. There will be a lot of fire and flame as the grease burns in the bearing. It takes quite a while to do this. Do not beat on the bearing or casting. Do NOT cool the casting, let it cool naturally, this includes not blowing a fan on it to cool it. The loop that holds the bearing can be broken very easily so let it be til ya can put your hand on it and it doesnt feel hot. NOTE: Do not pick up the old bearing with your hands intil it is cool, it will set YOU on fire LOL !
You can seat the new bearing with an arbor press but make darned sure the seat is clean and the new race is clean. Make sure everything is level before ya put any pressure on it. Use the proper matching rings etc. ( do not just use random pieces of stock laying around the shop, use a full ring ) to elevate all the parts then a ring only on the seat set it gently and perfectly square. No pressure on the inside race or bearings. Once set remember to grease the hell out of it.
If anyone else can add anything to this or a better or even just different way you have found, please let us all benefit from you'r knowledge. Especially the lower bearing removal and installation. This is a super easy place to damage a Franklin unit.
Scotty
There are four bolts in the lower bearing, and it will usually be a little stuck in the lower aluminum housing.
The good news is that the bearing cap itself is threaded, so if that lower bearing doesn't want to come free from the pilot shaft you can rotate the bearing cap just a little to cover the holes in the case and then screw those four bolts back in against the case and use them to press the bearing out a little to unseat it. Work patiently and you shouldn't have to heat the case.
Keep in mind that when you remove the nine bolts around the upper drum it may want to fall out and it is very heavy, so keep a top bolt in it to safety it until you and another person are in place to catch it when it comes free. The perimeter of the upper drum is ground on an eccentric so you can adjust the belt tension. You may need to rotate it slightly counter clockwise to loosen it's grip on the drive belt to slide it out.
Keep in mind also that you're using Grade #8 hardware that is being screwed into aluminum threads, so when you go back together be very careful not to overtorque the bolts in the case at the upper and lower pulleys. I don't use more that 25 ft. lbs. on them, with blue Locktite.
Torque the bolts that mount the case to the engine to 35 ft. lbs., and Locktite them too. Hope this helps.
The good news is that the bearing cap itself is threaded, so if that lower bearing doesn't want to come free from the pilot shaft you can rotate the bearing cap just a little to cover the holes in the case and then screw those four bolts back in against the case and use them to press the bearing out a little to unseat it. Work patiently and you shouldn't have to heat the case.
Keep in mind that when you remove the nine bolts around the upper drum it may want to fall out and it is very heavy, so keep a top bolt in it to safety it until you and another person are in place to catch it when it comes free. The perimeter of the upper drum is ground on an eccentric so you can adjust the belt tension. You may need to rotate it slightly counter clockwise to loosen it's grip on the drive belt to slide it out.
Keep in mind also that you're using Grade #8 hardware that is being screwed into aluminum threads, so when you go back together be very careful not to overtorque the bolts in the case at the upper and lower pulleys. I don't use more that 25 ft. lbs. on them, with blue Locktite.
Torque the bolts that mount the case to the engine to 35 ft. lbs., and Locktite them too. Hope this helps.