View Full Version : Jackshaft bearing replacement

Scott Long
10-03-2013, 05:17 PM
This past weekend I found out that my spare accessory bracket has a bad jackshaft bearing. Is there a source to get these pressed and replaced?

10-03-2013, 05:27 PM
Seen these threads?

http://www.sccoa.com/forums/showthread.php?t=94844&highlight=Jackshaft+bearing+replacement - 51 replies - last one in July this year

http://www.sccoa.com/forums/showthread.php?t=60725&highlight=Jackshaft+bearing+replacement - 8 years back it looks

Scott Long
10-03-2013, 05:46 PM
Ok well its hit or miss. There is no good info I can find on a bearing I can buy and take to get pressed in. ESM might do it still but that hasn't been confirmed. If Wade Embree can do it, he must have a source for the bearings...

10-04-2013, 01:04 PM
I think Wade breaks open the cartridge bearing and re-machines the shaft so it fits a standard-style bearing. Or takes a different cartridge bearing off the shelf and machines the end of the shaft so that it fits the JS pulley.

Either way, I don't think he is just popping in a bearing.

10-04-2013, 05:18 PM
Just glancing at McMaster-Carr they have Tapered-Roller bearings that could be made to work for ~$40 each plus machine work, or ~$30 for Needle bearings.

10-04-2013, 06:18 PM
i contacted ESM back in the spring and he was no longer repairing SC jackshafts. He checked and did not have any good ones left that he could send me either. I ended up picking up a used passenger side accessory bracket with the intent of having one ready to make a custom piece by a machine shop when the time came.

10-04-2013, 08:09 PM
Just glancing at McMaster-Carr they have Tapered-Roller bearings that could be made to work for ~$40 each plus machine work, or ~$30 for Needle bearings.

Not a bad idea. I think, if we used plain ball or roller bearings, we would need to cut a groove for a retaining ring on the back end of the shaft. Otherwise, only the shaft's fit to the bearing would prevent it from shooting right out the front. (This shaft doesn't press into a bearing in the stock setup ... it is the inner race on which the balls ride, and is therefore retained by the balls.)

10-05-2013, 08:45 AM
I will admit this is above my knowledge level, but I can get the opinion of our head machinist at work.

Dimensions off shaft would be nice to tell him, and RPM (or at least the ratio of Jackshaft to Crank)

10-05-2013, 10:15 PM
most bearing details can be found in this thread:

10-07-2013, 06:08 PM
Talk to him today and said this was above his ability. Did mention getting someone with a fixture (for machining the bracket) might be an issue, implied needle bearing might be the way to go because of this.

J dot Miller
10-07-2013, 08:11 PM
Not sure how helpful this is but...

As per the links the bearing P/N is 885925. I found the following (se the attachment for further details):

WIB2548112 47.625 69.85 25.4 112.27 37.97 .7KG

D1 and B1 were not dimensioned.

It will be nice if we can get more info on the original bearing. Something like the ABEC class will be useful in finding a suitable replacement.

10-07-2013, 08:19 PM
So if I read it right shaft dia is 47mm and Bearing OD is 69mm

And looking a McMaster-Carr leaves one option that I see http://www.mcmaster.com/#7929k48/=ou7izo

Would require a sleeve (69mm down to 2" 5/16) in the bracket, which may solve the machining issue. Though the RPM does concern me.

10-08-2013, 12:36 AM
No, the OD is 47.625 mm, which is 1-7/8". The shaft is 1", but seems to neck down to 3/4" to receive the pulley mounting flange, and then necks down again to 5/8" to locate the pulley.

Bearings in inch sizes are rare these days.

I looked into it a bit today, and I think the most likely way to make the separate bearings idea work is:
- Press out the old bearing
- Carefully cut it apart and save the shaft. If it can't be saved, machine a new shaft from steel stock, holding proper tolerances at each point along the shaft.
- Press off the pulley flange
- Turn down the shaft to 3/4" to fit the new bearings.
- Press a steel sleeve into the aluminum housing to step it down from 1.875" to 1.745".
- Hone out the housing to the proper fit for a 1.75" OD bearing
- Press two 1635-2RS bearings into the sleeve, using a steel sleeve of 1.75" OD as a spacer.
- Press the shaft into the two bearings, supporting one of the bearing outer races from the back end so you don't press them right out of the steel sleeve.
- Press the pulley mounting flange back onto the shaft
- Hey presto!

When you add it all up, it's a lot of trouble.

Our best option may in fact be to call those Chinese fellows and ask them to whip up some bearings for us.

See info in later post regarding John Deere bearing. Intriguing possibility!

10-09-2013, 05:21 PM
Shaft dia is 3/4", would it not be measurement d which is 25.4mm or 1"?

Also by my quick measurements I get a drive ratio of 1:1.794 for stock pulley setup (Crank pulley size/Jackshaft pulley size). Without overdrive to me that means need a RPM of ~11,000RPM

10-09-2013, 06:15 PM
Shaft dia is 3/4", would it not be measurement d which is 25.4mm or 1"?

Also by my quick measurements I get a drive ratio of 1:1.794 for stock pulley setup (Crank pulley size/Jackshaft pulley size). Without overdrive to me that means need a RPM of ~11,000RPM

I studied pictures of a disassembled bearing again and I decided you are correct. I guess the shaft is 1" in diameter all the way through the bearing. But according to "woodrow" in this thread:

The 1" shaft comes out the bearing, then necks down to 3/4" for the pulley flange, and then down to 5/8" for the pulley itself.

I have updated the post above with corrected information, just to avoid misleading anyone.

10-09-2013, 07:11 PM
Well if that is the case then looks fairly simple.
Get sleeve made with interference fit (FN2 ?) for bracket and bearings

I see bearing option (once again going to McMaster-Carr) being http://www.mcmaster.com/#7929k43/=ov7ez2, then need to find a seal IMO.

10-09-2013, 07:34 PM
That looks ok, but I wonder if the rollers will hold up. What are the thrust (axial) loads acting on the bearing? I am not sure. But I know that needle roller bearings are not rated for thrust loads of any significant amount. Ford used two ball bearings, and I am guessing that it was for a good reason. I have seen some water pump bearings that have one roller bearing and one ball bearing in the same housing.

You could use R14 or S9 ball bearings that would fit the 1-7/8" housing, but you would have to turn the shaft down to 7/8". It looks like ball bearings of 1" bore only come in 2" OD.

But I have heard concerns about the rigidity of the aluminum housing which make me think that a steel sleeve might be a nice idea. However, if you do that, you have to step down the OD to 1-3/4", which means you can't find any ball bearings with an ID bigger than 3/4", which means you have to turn down the shaft even further.

The roller bearings give more fitment options, but I just don't know if they are okay for this application.

Very frustrating.

I actually found a water pump bearing with the proper OD and shaft diameter that may be available ... it's John Deere part JD10058.


If looks like the shaft is long enough, but a little machining would still be required to turn down the shaft to fit the pulley flange on. It's not cheap to start with, either, at about $70.

From the limited number of suppliers I see on line, I am guessing the John Deere bearing is also discontinued and is just new old stock now. Maybe the same factory made both bearings and just threw that machine away at the turn of the millennium?

Double edit:

Hello, we may have hit paydirt. From the Surplusman pictures, I thought I could see "KOYO JAPAN" on the seal on the end of the bearing. I dug and found this PDF (http://www.wills-asoc.com/KOYOVs.OEM.pdf) that implies that KOYO made it for John Deere. I couldn't find any other references to those internal KOYO part numbers, but I did notice that another John Deere water pump bearing was listed. That bearing is JD8643. That bearing seems to have the same OD, the same shaft diameter (inside the bearing), and an even longer shaft. It's also cheaper and looks more available.

From the image I see, it looks like one end of the shaft is 1", and the other one may even be 5/8". I guess one could machine two steps into the 1" part of the shaft and cut off the 5/8" part as needed, or press a 3/4" sleeve onto the 5/8" part of the shaft, and cut off the 1" part as needed.

Thinking about ordering one to measure up.

10-09-2013, 09:33 PM
I'll have to reread all that for it to all sink in but that John Deere on may be the best option RPMs still concern me though. Being in farm country I can check with one of the local JD places an see the status of JD8643.

My though on the needle bearing was to use at least 2 bearings, one at each end of the shaft. Thrust load don't know either may be a seat of the pants issue there. Though would it not be some vector of both belt tensioners?

12-10-2013, 08:35 PM
Hi, I am new to this forum thing, so bear with me please. I have been searching for a jackshaft bearing for a while now and finally FOUND a supplier!!! I have placed my first order and should have them in my hands in about a week. These will be available for sale on a first come first serve basis for about $150.00 ea. These are supposed to be true NSK bearings not Chinese after markets. I will repost once they are in my hot little hands, to let all know for sure brand and price. Please let me know if you are interested. Thank you.

12-12-2013, 03:05 PM
If an original NSK 885925 was available would there be interest in just the bearing or an actual rebuilding service?

I'm asking because I read this thread and contacted my bearing supplier, he found some and has a couple on their way to me. I'll compare these to the originals. If they are the same I'll offer them to whoever wants them, im not looking to get rich off of these either just trying to help people out. I also do not know if the supply is limited or not, once i verify its the correct bearing ill see how many are available.


good to doo
12-13-2013, 10:22 AM
just curious here, were the js pulley diameters the same over the years? I have a couple of spares from early 90s cars, but my current car is a 95. thanks all.

12-13-2013, 12:46 PM
just curious here, were the js pulley diameters the same over the years? I have a couple of spares from early 90s cars, but my current car is a 95. thanks all.

I think the JS pulley should be the same for all years of the SC.

12-17-2013, 09:38 AM
Ok, I have received my bearings, and they are NOS NSK # 885925. I have 3 extras available for sale at $100.00 each. This price includes shipping to the 48 continental states. Let me know if any of you are interested. I do accept paypal and would be open to trades as well. I have 10 cars, mustangs, tbird, mark8,f250,and even a couple of old GM products, so let me know what you have to offer. Thank you, I hope the time I spent to locate these can help someone fix or save their SC.