NP205 Idler Bearing Shims

How they work, how they don't work, and how to fix them

Moderators: Greenleaf, BC847, Richie O

NP205 Idler Bearing Shims

Postby coodah » Sat Mar 29, 2014 8:53 pm

Rebuilding the 205 in my 90 Cummins, using a rebuild kit I bought on Ebay. After installing new bearings and races in the idler gear I tried installing it and found out I need some addional shims. Quad 4X4 wants $40 for a shim kit which is way too high. Is there anyone else out there that sells them cheaper? I did find Mc Master Carr has round shim kits for about $16.92, 1 3/8" I.D. x 1 7/8" OD. , part #3088A939.
90 W350 Cab-Chassis Truck, 5 spd, 93 W250 CC 5spd
coodah
fuel screw!!!!
 
Posts: 33
Joined: Thu Feb 25, 2010 7:21 pm
Location: North East Missouri

Re: NP205 Idler Bearing Shims

Postby bgilbert » Sun Mar 30, 2014 11:53 am

Do you mind me asking how you determined you need more shims? All the ones I've done didn't need more than the original shims it had before rebuild. As far as a source for shims, I would contact Craig at www.zbag.com and see what they have. You should never buy anything from high dollar Quad$x$. lol
Bill Gilbert
85 D350 crew with 90 6BT intercooled Getrag 3.07's
93 D350 single cab Getrag 3.54's.
bgilbert
14mm rotor
 
Posts: 2253
Joined: Wed Jan 03, 2007 5:04 pm
Location: Terre Haute, Indiana

Re: NP205 Idler Bearing Shims

Postby coodah » Sun Mar 30, 2014 7:58 pm

Thanks for responding Bill, it had two shims between the bearings and the tube spacer when I opened it up. When I took it aparts it looked to me like I wasn't the first person inside of it. There was blue silicone seal all over the place. I installed the cups and cones and assembled it with the original shims. I started tightening the nut on the idler shaft and when I got to 60 ft.lbs the idler gear was hard to turn. Somewhere I read it should be torqued to 150. I assume that I need to add more shims. Based on the many post I have read of yours you have a heck of lot more experience than I do rebuilding these. I would appreciate any advice you may have. Thanks, Curt
90 W350 Cab-Chassis Truck, 5 spd, 93 W250 CC 5spd
coodah
fuel screw!!!!
 
Posts: 33
Joined: Thu Feb 25, 2010 7:21 pm
Location: North East Missouri
Top

Re: NP205 Idler Bearing Shims

Postby bgilbert » Mon Mar 31, 2014 10:25 am

coodah wrote:Thanks for responding Bill, it had two shims between the bearings and the tube spacer when I opened it up. When I took it aparts it looked to me like I wasn't the first person inside of it. There was blue silicone seal all over the place. I installed the cups and cones and assembled it with the original shims. I started tightening the nut on the idler shaft and when I got to 60 ft.lbs the idler gear was hard to turn. Somewhere I read it should be torqued to 150. I assume that I need to add more shims. Based on the many post I have read of yours you have a heck of lot more experience than I do rebuilding these. I would appreciate any advice you may have. Thanks, Curt

Adding more shims would only make it even more tighter. An easy way to set it up/check endplay is to assemble the idler gear outside of the case with both bearing bearings and races, the spacer and shims and the idler shaft through the assembly. Place the assembly in a shop press. Use a large socket that fits on the threaded end of the shaft, and over the bearing. Apply a bunch of force from the press. Then using a dial indicator on a magnetic base you can pry up on the gear with a screwdriver and check for endplay. You want no more than .002. A dial indicator could be used too. The same measuring procedure is done with the gear assembly in the case. But if you need to add or remove shims it's easier on the press. The torque spec I use from a 205 rebuild video I have is 138ftlbs on the idler gear/nut.
bgilbert
14mm rotor
 
Posts: 2253
Joined: Wed Jan 03, 2007 5:04 pm
Location: Terre Haute, Indiana
Top

Re: NP205 Idler Bearing Shims

Postby coodah » Mon Mar 31, 2014 8:27 pm

Bill, I'm not sure I follow you. When I pulled the idler gear from the case I did not specifically see where the shims were located. They fell out and were laying in the case. I have been using this instruction set, http://www.wideopen4x4.com/NP205RebuildGuide.html and it shows the shims located between the two bearings. I have a General Motors service manual for rebuilding the 205 and it shows the shim being placed on the idler shaft, then the shaft is inserted through the case, through the first bearing, then the spacer, next the other bearing and then through the case, finished up by the washer and nut. Which way is correct? I have the shims between the bearings which should limit how much they are compressed in the cups. By adding shims this should give me less pre-load. If I follow what you are saying about adding shims will increase my pre-load, then I assume you are placing them on the outside of the bearings, like the GM manual shows, which makes sense. It looks as if the idler shaft basically floats in the case with a slight press fit. By torqueing the nut you are compressing the bearings and adding pre-load. It doesn't appear that the by tightening the nut I will compress the sides of the case creating my binding problem. Sorry for the long reply. Your setup procedure with a press is a good idea but shim location, inside/outside the bearings has opposite affects. Any help will be appreciated. Thanks, Curt
90 W350 Cab-Chassis Truck, 5 spd, 93 W250 CC 5spd
coodah
fuel screw!!!!
 
Posts: 33
Joined: Thu Feb 25, 2010 7:21 pm
Location: North East Missouri
Top

Re: NP205 Idler Bearing Shims

Postby bgilbert » Tue Apr 01, 2014 4:57 pm

I've never seen shims on both sides of the 'spacer', only on one side. Wide open's rebuild doesn't show how to check for endplay or is it freeplay? Not cool. I would do it like they show in step 39, minus 'two sets of shims'. It should be in this order: bearing on bottom, idler gear, spacer down into gear/on top of bearing, shims on top of spacer, then last bearing ontop of shims. Slide assembly into the case.

It's easier to put the idler gear in the transfer case before stacking the spacer, shims and 'upper' bearing than the way Wide Open describes it. A little bearing grease to hold the spacer and shims in place will help. Same thing with all the needle bearings.

Did you drive the races/cups completely into the idler gear?
Bill Gilbert
85 D350 crew with 90 6BT intercooled Getrag 3.07's
93 D350 single cab Getrag 3.54's.
bgilbert
14mm rotor
 
Posts: 2253
Joined: Wed Jan 03, 2007 5:04 pm
Location: Terre Haute, Indiana
Top

Re: NP205 Idler Bearing Shims

Postby coodah » Tue Apr 01, 2014 8:10 pm

Thanks again for responding, I did drive the new cups completely in the idler gear. I installed the bearing, spacer, shims, then bearing as you described. I made myself a dummy shaft 4" long and 1.360" dia. and inserted it through the assembly. I then installed it into the case. I then tapped the idler shaft through the assembly driving out my dummy shaft. Everything worked perfect and the gear spun smooth until I started tightening up the retaining nut. Once I got to about 60 ft/lbs the gear started to bind. I assume the bearing pre-load is too tight that is why I want add shims. I ordered the shim kit from Mc Master Carr and got it this morning. It looks like they will work perfect. I plan on taking the parts to work tomorrow and use the procedure you described using a press to find the shim stack I need.
On another note I see where you are going to the Iowa meet in June. I'm making plans to go as well and look forward to meeting you there. Thanks for the help, Curt
90 W350 Cab-Chassis Truck, 5 spd, 93 W250 CC 5spd
coodah
fuel screw!!!!
 
Posts: 33
Joined: Thu Feb 25, 2010 7:21 pm
Location: North East Missouri
Top


Return to Transmission

Who is online

Users browsing this forum: No registered users and 10 guests