6203 DD Bearing - keep or change?

[catzr]

6203 DD bearing

I have an 011 M8 with the pocket brg. failure.
I determined that I had the narrow tunnel problem.
I did things a little different. I kept the 6203 brg.
I shimmed the DD out .085 from the tunnel. That seemed to relieve the sideload
on the DD. By checking it with the cover off. I had a .055 shim behind the sec. clutch that I removed to compensate for alignment.
Then I had to removed .020 from the shim the 6203 brg. so the DD cover would sit flush. The 6203 brg. didnt have a chance of living with the factory set up.
I think by taking the sideload off the 6203 it may have a chance.

 

[Diamond8]

I did the 5203 bearing ( SKF Brand Sealed ) on my 2010 and two other buddies 2010's and one 2009 M8. Machining the shoulder down on the transfer gear to try and position the double row 5203 as close to that of the original bearing and spacer. What I found was that the stack up of the original bearing and spacer varied a few thou. from sled to sled. They were all a little different. Just for good measure in case I was dealing with a narrow tunnel I took around 0.010" thou. more to give a little room.

Well had the sleds apart for maintenance this fall and all of them look great! Now.........a couple of the sled only have a couple hundred miles on them since the change but mine and one other have around 800-900 miles and the bearings looked great........rolled smooth and felt solid.....no slop. Made me feel good to crack the cases and find everything in great shape. Just thought I would give my report.

 

[Coldfinger]

I pulled the DD yesterday on my 2010 and the 6203 I put in 1200 miles ago is just starting to fail.

The original bearing went about 800 miles and the cage was falling apart and there were about 3-4 balls hitting each other. The inner seal was also knocked out of place.

I replaced with an SKF6203 2rs because it wasn't clear at that time what the exact fix was. this bearing lasted 1200 miles, so 1.5 times as long as the OEM. The bearing looked good but had a smidge of lateral freeplay so I popped the seal and saw the cage was cracked and loose in a few spots. Also, there was no visible grease in the bearing, only an oil film.

I've been running Cat DD oil. Stock sled. Debating which bearing to go with and if I want the 2 rubber seals on the bearing.

 

[boondocked]

Is it true that if you use the 4203 bearing you don't have to machine the shaft,
I thought I read it fit perfect, but can' t find that tread

 

[Coldfinger]

Yes, the 4203 is narrower than the 5203 and 3203, BUT, it is NOT an angular contact bearing and it is harder to find. I think it is a stronger bearing than the 6203.

I'm real tempted right now to try the 6203 without seals because I'm tending to believe, for some reason, the grease is being washed away by the oil and the seals being in place prevents enough oil from lubing the bearing and thus the bearing starts to fall apart. When the bearing cage finally knocks the seal out, then more lube can enter but since the bearing is already compromised it is only a matter of time till it fails completely.

It is a common bearing (6203) at the auto stores and if I would probably be pulling my DD each 1,000 miles to check/clean anyhow, so it would be easy to replace the bearing at that time.

 

[boondocked]

Sorry , but what does" no angular contact mean,"
and how is that different, or effect the running.
Not a bearing expert by any means,

Just getting ready to plug dd, in a month, what to make sure I'm prepared
Tx

 

[Coldfinger]

I'm no expert either, but as I understand it, an angular contact bearing is built to better withstand side-loading. As I've read, it seems numerous people have said there is pressure from the side when everything is tightened up. Some have had a few thousandths shaved off the end/s of the driveshaft to eliminate/reduce the side load.

Now that I think about it, I don't have a clear understanding what the benefit is for those that only choose to have their transfer gearshaft machined back so the wider 5203 bearing rests in the same relative position as the OEM6203 w/spacer. I'll have to look at my DD again to see how that transfer gear rests in the ring gear, but I'm thinking if the ring gear surface where the end of the transfer gear/bearing butts up against is flat, then as long as the 5203 bearing does not extend past the end of the shaft all should be fine?

On edit - I heard the factory fix is to measure how much side loading there is and change the shim washer under the 6203. Some require up to .007", or .2mm less shim thickness.

 

[Coldfinger]

RPM of 6203 bearing

First, re my previous post - after looking at my DD tonight, the bearing rests against the ring gear so IMHO, installing a 5203 without machining back the shoulder of the transfer gear will cause the transfer gear to not seat into the ring gear far enough causing mis-alignment of the teeth. This has been mentioned in previous posts. Sorry for the rehash. If I was going to do the 5203, I'd have the transfer shaft machined back so the end of the 5203 sits back maybe .005" further on the shaft vs the OEM 6203 (end) position.

Now, I took the DD and placed a piece of tape on the shaft splines that go into the axle, and a piece of tape on the transfer gear. Next I turned the shaft and for each two turns approx., the ring gear turned once.

If our sleds have 9" drivers, those drivers will be turning approx. 11,200 rpm to go 60mph, and 13,065 rpm to go 70. I seem to recall many of the bearings I looked at that were rated for 12,000 rpm.

 

[knoba]

Narrow tunnel

My tunnel was too narrow at the bottom and OK at the top so i bent the tunnel out at the bottom to remove the axial load on the bearing.I will be using a 4203 SKF open bearing.

 

[Coldfinger]

Well, after much deliberation, I stayed with the 6203 but went to an open bearing and I shaved the shim washer a little thinner. Figured I was going to be checking the bearing each season anyhow so why not. I'm curious how the open will hold up anyhow, and I figure in another 1000 miles I'll be changing the brake side bearings.

 

[L4t3]

Took the original bearing out for inspection at 500 km and it was fine. Replaced it with 6203 without any seals, that was the recommendation from a guy who sells bearings for a living. I now have over 1000 kms with that open bearing. Haven`t opened the dd since, but it runs good and every time I change the oil, it`s crystal clear without any debris in it.

 

[runner]

I have an 011 M8 with the pocket brg. failure.
I determined that I had the narrow tunnel problem.
I did things a little different. I kept the 6203 brg.
I shimmed the DD out .085 from the tunnel. That seemed to relieve the sideloadon the DD. By checking it with the cover off. I had a .055 shim behind the sec. clutch that I removed to compensate for alignment.
Then I had to removed .020 from the shim the 6203 brg. so the DD cover would sit flush. The 6203 brg. didnt have a chance of living with the factory set up.
I think by taking the sideload off the 6203 it may have a chance.

Yes I believe side loading on that bearing is the real problem.
I just did something similar but different, I shimmed the brake caliper out .125" Correction, used a .085" shim.

You need to bolt the D.D. and caliper in place without the driveshaft and measure the distance between the brake bearing and DD output shaft and compare it to the lenght of the driveshaft, include the bearing shield.

 

[Coldfinger]

Yes I believe side loading on that bearing is the real problem.
I just did something similar but different, I shimmed the brake caliper out .125"

You need to bolt the D.D. and caliper in place without the driveshaft and measure the distance between the brake bearing and DD output shaft and compare it to the lenght of the driveshaft, include the bearing shield.

Good idea on measuring that. I don't recall hearing that one before.

I thought about using the big brake caliper shim (between it and the tunnel) to trace a pattern, then have a sheet of aluminum cut to match the shim, then install that along with the thick shim to gain a little more clearance. Or, I suppose you could have a machine shop make a single thicker shim to replace the one that's there.

 

[runner]

Alumimum is easy to cut, a jig saw with a thin blade will work or even better use a scroll saw if you have one.

 

[knoba]

Tunnel

I think every one should check the tunnel at top and the bottom mine was 3mm narrower at the bottom than top,you could see with the track and driveshaft out that it was bent in.If i would have shimmed it i would have needed to just shim the bottom of the caliper side

 

[runner]

I think every one should check the tunnel at top and the bottom mine was 3mm narrower at the bottom than top,you could see with the track and driveshaft out that it was bent in.If i would have shimmed it i would have needed to just shim the bottom of the caliper side

The tunnel could even be out front to back.
Bolt the D.D. on with the driveshaft bolted to it then slide the caliper on all the way so the bearing shield it snug and you will see the gap you have, or not if everything is correct.

 

[knoba]

Tunnel

Runner i did bolt in the DD and drivshaft and snugged up the caliper nut but left the caliper to tunnel bolts loose that is when i saw the difference in the tunnel dimensions,at the bottom of the drivers it was 3mm narrower than at the top of the drivers.If i would have machined 3mm off the drive shaft there would have been an axial load pulling on the DD bearing.

 

[Coldfinger]

I'm no bearing expert. The guys at the bearing shop told me if there is side loading on the 6203 bearing you might be able to see it upon disassembly.

I got home and disassembled the bearing and examined real close looking at it backward thru binoculars. I could not see any evidence that either side of either or the races was worn.

 

[knoba]

Bearing

Coldfinger i am not sure if it is just the side loading causing the problem but in my case the 6203 bearing cage was gone in 200miles,the side load is one problem also a cheap single row bearing is another and i think there is no need for a sealed bearing.

 

[runner]

Even if the side loading is not the main cause of the failures having the driveshaft too long causes unnecessary side load and friction on that bearing, the bearing on the other end of that shaft, the D.D. output shaft bearing and the brake caliper bearings also.