Kevlar pilot bushings

Jim Caughlin · 11-19-2013, 11:58 AM

Anyone have experience with these? Obviously, the bronze bushings don't last. I currently run the needle bearing style but they have somewhat limited life as well. Just curious if the kevlar bushing is the answer. I'd like to hear if anyone has actual experience with these, not just something that you read in a magazine.

Jim Caughlin
SS 6019

SSDiv6 · 11-19-2013, 04:36 PM

Quote:

Originally Posted by Jim Caughlin

Anyone have experience with these? Obviously, the bronze bushings don't last. I currently run the needle bearing style but they have somewhat limited life as well. Just curious if the kevlar bushing is the answer. I'd like to hear if anyone has actual experience with these, not just something that you read in a magazine.

Jim Caughlin
SS 6019

Jim, if you do a search, a lot of people have suffered failures with the so called "Kevlar" pilot bushing.

Since I am familiar with the material, I did an internet search and what they are calling "Kevlar" is actually a Nylon bushing and the reason why they do not last. So in a nutshell, I believe they are selling a Nylon product by giving it a flashy name.

Kevlar's properties are not conducive for such application. Delrin or Polyether Ether Ketone (PEEK) materials would be.

FED 387 · 11-19-2013, 05:20 PM

GM had roller bearings for the 6.2 diesel that would interchange with a "stock" bronze Chevy bearing- not sure what you have been using but worth a look-- they would last a season or more at high rpms too with no difficulty--- machining one from delryn or other products should not be a problem for a good machinist you only need to get a source for some material to make the bushings---
FED 387

FED 387 · 11-19-2013, 05:32 PM

#14061685 is the GM part number for that bearing about $11-14 dollars--FED 387

Jim Caughlin · 11-19-2013, 09:01 PM

Didn't think about PEEK, we use it at work and it works very well as a wear surface, good idea. I currently use a GM size needle bearing unit, they last for a full season but do wear out. I had one come apart once and it was a royal pain to remove. Maybe it is best to just accept that they wear out on a yearly basis and need to be replaced. Just thinking about better ideas.

SSDiv6 · 11-19-2013, 09:07 PM

Quote:

Originally Posted by Jim Caughlin

Didn't think about PEEK, we use it at work and it works very well as a wear surface, good idea. I currently use a GM size needle bearing unit, they last for a full season but do wear out. I had one come apart once and it was a royal pain to remove. Maybe it is best to just accept that they wear out on a yearly basis and need to be replaced. Just thinking about better ideas.

PEEK will take the abuse and loads better than Delrin or Nylon.

james schaechter · 11-19-2013, 09:35 PM

We have run a kevlar bearing and it has done well. I think RAM sells or markets it. 3 seasons on it.
I would say that if you have the crank out, do it all the way and install a sealed bearing. Never ever had a failure there. From a 10,000 rpm modified to a stocker.

Bill Edgeworth · 11-19-2013, 11:54 PM

Quote:

Originally Posted by SSDiv6

PEEK will take the abuse and loads better than Delrin or Nylon.

PEEK is a great resin, way better than nylon and better than Delrin and also much more expensive. However I think there are some newer composite resins like Hydlar which I think is a Kevlar filled nylon that gives both strength and lubricity. The old glass filled nylons had good strength but also caused wear on the shafts they were supporting. (I'm speaking as a plastics guy, not specifically about transmission applications)

Not sure how easy it is to machine or suitable for a pilot bushing.......there is getting to be an awful lot of engineering resins on the market with special purpose fillers in them.

Run to Rund · 11-20-2013, 11:25 AM

South Bend Clutch used Kevlar bushings for a while in diesel applications.
Use your dial indicator to make sure the bellhousing is dead centered, and the trans surface is parallel to the block/crank flange. It is very common for them to be out. Lakewood etc. offer offset dowel pins.

Jim Caughlin · 11-20-2013, 01:00 PM

Maybe I'm missing something here, is there a sealed bearing (as opposed to an open cage type bearing) that will hold up? In my case, I'm using the open cage type. I pack it full of grease when I first install it but obviously a few 10,000 RPM launches and I assume all of that grease exits the bearing in a short period of time and the bearing is in an unlubed state and eventually fails. In additon, the grease flings into the bellhousing and makes a big mess. As the sealed bearing would not be a press fit onto the pilot, does it spin free enough to be effective or is it just going to gaul the pilot? I'm thinking of either machining a bushing out of PEEK and/or utilizing a sealed bearing that spins adequately free, either should improve my situation. Any thoughts?

11-19-2013, 05:20 PM	#3
FED 387 VIP Member Join Date: Jun 2006 Posts: 3,366 Likes: 391 Liked 298 Times in 158 Posts	Re: Kevlar pilot bushings GM had roller bearings for the 6.2 diesel that would interchange with a "stock" bronze Chevy bearing- not sure what you have been using but worth a look-- they would last a season or more at high rpms too with no difficulty--- machining one from delryn or other products should not be a problem for a good machinist you only need to get a source for some material to make the bushings--- FED 387

11-19-2013, 05:32 PM	#4
FED 387 VIP Member Join Date: Jun 2006 Posts: 3,366 Likes: 391 Liked 298 Times in 158 Posts	Re: Kevlar pilot bushings #14061685 is the GM part number for that bearing about $11-14 dollars--FED 387

11-19-2013, 09:01 PM	#5
Jim Caughlin Senior Member Join Date: Mar 2002 Location: Woodburn, Or Posts: 640 Likes: 73 Liked 709 Times in 213 Posts	Re: Kevlar pilot bushings Didn't think about PEEK, we use it at work and it works very well as a wear surface, good idea. I currently use a GM size needle bearing unit, they last for a full season but do wear out. I had one come apart once and it was a royal pain to remove. Maybe it is best to just accept that they wear out on a yearly basis and need to be replaced. Just thinking about better ideas.

11-19-2013, 09:35 PM	#7
james schaechter VIP Member Join Date: Dec 2004 Location: Cumming GA Posts: 1,943 Likes: 1,121 Liked 1,299 Times in 261 Posts	Re: Kevlar pilot bushings We have run a kevlar bearing and it has done well. I think RAM sells or markets it. 3 seasons on it. I would say that if you have the crank out, do it all the way and install a sealed bearing. Never ever had a failure there. From a 10,000 rpm modified to a stocker. __________________ James Schaechter 3163 STK

11-20-2013, 11:25 AM	#9
Run to Rund Senior Member Join Date: Sep 2007 Location: Henderson, NV Posts: 577 Likes: 7 Liked 46 Times in 24 Posts	Re: Kevlar pilot bushings South Bend Clutch used Kevlar bushings for a while in diesel applications. Use your dial indicator to make sure the bellhousing is dead centered, and the trans surface is parallel to the block/crank flange. It is very common for them to be out. Lakewood etc. offer offset dowel pins.

11-19-2013, 11:58 AM	#1
Jim Caughlin Senior Member Join Date: Mar 2002 Location: Woodburn, Or Posts: 640 Likes: 73 Liked 709 Times in 213 Posts	Kevlar pilot bushings Anyone have experience with these? Obviously, the bronze bushings don't last. I currently run the needle bearing style but they have somewhat limited life as well. Just curious if the kevlar bushing is the answer. I'd like to hear if anyone has actual experience with these, not just something that you read in a magazine. Jim Caughlin SS 6019

11-20-2013, 01:00 PM	#10
Jim Caughlin Senior Member Join Date: Mar 2002 Location: Woodburn, Or Posts: 640 Likes: 73 Liked 709 Times in 213 Posts	Re: Kevlar pilot bushings Maybe I'm missing something here, is there a sealed bearing (as opposed to an open cage type bearing) that will hold up? In my case, I'm using the open cage type. I pack it full of grease when I first install it but obviously a few 10,000 RPM launches and I assume all of that grease exits the bearing in a short period of time and the bearing is in an unlubed state and eventually fails. In additon, the grease flings into the bellhousing and makes a big mess. As the sealed bearing would not be a press fit onto the pilot, does it spin free enough to be effective or is it just going to gaul the pilot? I'm thinking of either machining a bushing out of PEEK and/or utilizing a sealed bearing that spins adequately free, either should improve my situation. Any thoughts?