91 Seal Replacement
Moderator: Rob Voska
-
Dennis Detweiler
- Posts: 65
- Joined: Wed Nov 14, 2007 9:35 pm
- Vintage Karting items owned: 1961 Simplex
1974 Margay Concept Sprint
1984 Margay SR-16
Mc91b1 - Location: Iowa
91 Seal Replacement
What's the best method to remove the seal on the flywheel side?
-
steveohara
- Posts: 411
- Joined: Thu Jul 19, 2007 2:29 am
- Vintage Karting items owned: 1969 Bug Sprint Mc 91B1
1965 Dart Gran Prix twin Mc100s
1963 Bug Scorpion ESll Mc45
Re: 91 Seal Replacement
Dennis,
Remove the crank and bearing (they should come out together) and place the side cover on a firm flat surface with the bearing side down. If you have no points installed you can use a large socket that is just a little smaller than the OD of the seal and push the seal out in the direction toward the bearing location. If you have access to a press that is great but without on you can just tap the seal out gently. If your points are installed and you don't want to remove them you can use a long drift to punch the seal out.... be sure to avoid scraping the surface the seal presses into. Once it is out you may see that an adhesive ws used to insure against leakage so you need to clean that stuff out.... best to use chemicals rather than scraping or sanding.... you don't want to enlarge the opening the seal fits into. When you install the new seal make sure you have a nice clean OD on the seal with no scratches or dings (polish them off if you have any) and use a sealant like Loctite or something similar to fill any imperfections. The new seal should be installed from the bearing side and only needs to be pressed in flush with the bottom of the bearing pocket. They go in easier if you warm up the side plate but you don't need to make it so hot that you can't touch it. To press the seal in you place the cover on the flat surface with the bearing side facing up and place the seal in position and push it in as far as it will go by hand (it will start to go due to the radius on the outside corner of the seal) then put a flat plate on top that it large than the seal and press or tap it in until the flat plate bottoms all the way around againd the bearing pocket. That's it.... pretty simple. If you were a shop doing a buch of them all the time you would have special tools to remove the seal with the crank in place and install a new one.... they are hard to find these days. The removal too looked like a giant "easy out" with a hole in the center for the crank and you pushed it in and turned it to lock into the seal, then backed it off with a bolt against the end of the cranks just like any common puller. The install tool was just a cylindrical tool slighty smaller in OD than the seal ong enough to have a hole board in it for the crank and you could shove the new seal in from the flywheel side. I never liked doing them that way as it is just about impossible to get everything clean enough without risk of getting junk in the bearing.
Good luck!
Steve O'Hara
Remove the crank and bearing (they should come out together) and place the side cover on a firm flat surface with the bearing side down. If you have no points installed you can use a large socket that is just a little smaller than the OD of the seal and push the seal out in the direction toward the bearing location. If you have access to a press that is great but without on you can just tap the seal out gently. If your points are installed and you don't want to remove them you can use a long drift to punch the seal out.... be sure to avoid scraping the surface the seal presses into. Once it is out you may see that an adhesive ws used to insure against leakage so you need to clean that stuff out.... best to use chemicals rather than scraping or sanding.... you don't want to enlarge the opening the seal fits into. When you install the new seal make sure you have a nice clean OD on the seal with no scratches or dings (polish them off if you have any) and use a sealant like Loctite or something similar to fill any imperfections. The new seal should be installed from the bearing side and only needs to be pressed in flush with the bottom of the bearing pocket. They go in easier if you warm up the side plate but you don't need to make it so hot that you can't touch it. To press the seal in you place the cover on the flat surface with the bearing side facing up and place the seal in position and push it in as far as it will go by hand (it will start to go due to the radius on the outside corner of the seal) then put a flat plate on top that it large than the seal and press or tap it in until the flat plate bottoms all the way around againd the bearing pocket. That's it.... pretty simple. If you were a shop doing a buch of them all the time you would have special tools to remove the seal with the crank in place and install a new one.... they are hard to find these days. The removal too looked like a giant "easy out" with a hole in the center for the crank and you pushed it in and turned it to lock into the seal, then backed it off with a bolt against the end of the cranks just like any common puller. The install tool was just a cylindrical tool slighty smaller in OD than the seal ong enough to have a hole board in it for the crank and you could shove the new seal in from the flywheel side. I never liked doing them that way as it is just about impossible to get everything clean enough without risk of getting junk in the bearing.
Good luck!
Steve O'Hara
-
Jeff Campbell
- Site Admin
- Posts: 580
- Joined: Tue Jun 12, 2007 7:52 pm
- Vintage Karting items owned: 1961 Fox Go-Boy MC20's
Robron Chaparral dual MC101
Margay Cheetah MKIII - Location: West Bloomfield, MI
- Contact:
Re: 91 Seal Replacement
Steve or others,
The one aspect that I have struggled with, is assembling the engine after installing the seal, or installing the seal into an assembled engine (onto the crank and into the block or sidecover at the same time). The problem I encounter many times is that the seal lip folds back enough for the spring to pop out, and this is VERY hard to detect that it has happened since you can't see it. I have noticed that if the seals are conditioned, by placing on a crank for several days, or maybe heating in a low temp 200F oven a few minutes, can make them slip onto the crank easily without causing the seal lip to fold and spit out the spring. Any tricks here?
Jeff
The one aspect that I have struggled with, is assembling the engine after installing the seal, or installing the seal into an assembled engine (onto the crank and into the block or sidecover at the same time). The problem I encounter many times is that the seal lip folds back enough for the spring to pop out, and this is VERY hard to detect that it has happened since you can't see it. I have noticed that if the seals are conditioned, by placing on a crank for several days, or maybe heating in a low temp 200F oven a few minutes, can make them slip onto the crank easily without causing the seal lip to fold and spit out the spring. Any tricks here?
Jeff
Re: 91 Seal Replacement
Very thin wall tube. Polish the OD and the hole just slips over the crank. Install in seal then check spring then install then remove thin tube and your done.
-
Dennis Detweiler
- Posts: 65
- Joined: Wed Nov 14, 2007 9:35 pm
- Vintage Karting items owned: 1961 Simplex
1974 Margay Concept Sprint
1984 Margay SR-16
Mc91b1 - Location: Iowa
Re: 91 Seal Replacement
where do you get the thin wall tube of correct ID size?
-
ted johnson
- Posts: 1685
- Joined: Fri Jun 15, 2007 7:59 am
Re: 91 Seal Replacement
Google on seal protectors. I've used the ones dad gave me 40+ years ago. Here's one possibility, though I don't know if they have the right sizes.
http://www.mawonline.com/newsite/tech_s ... ectors.htm
Good luck. Ted
http://www.mawonline.com/newsite/tech_s ... ectors.htm
Good luck. Ted
-
ted johnson
- Posts: 1685
- Joined: Fri Jun 15, 2007 7:59 am
Re: 91 Seal Replacement
P.S. Here's a PDF with good general info on seal installation:
http://www.sealing.com/fileadmin/docs/L ... lation.pdf
Ted
http://www.sealing.com/fileadmin/docs/L ... lation.pdf
Ted
-
steveohara
- Posts: 411
- Joined: Thu Jul 19, 2007 2:29 am
- Vintage Karting items owned: 1969 Bug Sprint Mc 91B1
1965 Dart Gran Prix twin Mc100s
1963 Bug Scorpion ESll Mc45
Re: 91 Seal Replacement
If the seal is in place and you are installing the crank, lube the seal and the crank with a light grease or heavy oil and then keep turning the crank as you push it through the seal. Watch the seal from the outside as you are pressing the crank in slowly and you will see the seal start to deform if it doesn't slip over the step on the crank. If I see the seal start to deform I use a tiny flat screwdriver to assist the seal up an over the step while still turning the crank back and forth.... pretty easy if you are paying attention.
The fool proof method is to have the thin wall tubing but that is a tool that is hard to come by. An alternative to the thin wall tubing I have seen used is a piece of .010" thick shim stockcut and rolled into a sleeve and inserted in the seal to use as a guide. I don't like the method much.... worried about the edge cutting the seal if pulled out wrong.
Steve O'Hara
The fool proof method is to have the thin wall tubing but that is a tool that is hard to come by. An alternative to the thin wall tubing I have seen used is a piece of .010" thick shim stockcut and rolled into a sleeve and inserted in the seal to use as a guide. I don't like the method much.... worried about the edge cutting the seal if pulled out wrong.
Steve O'Hara