AUX shaft bearings

[Dales78]

Hi guys! I've been hanging around here for a while but I’ve been too busy with the X1/9s to start on the Spider.

Now the time has come and I’m starting the rebuild of the 2L motor for the Spider. Question is, I’ve heard from a couple of sources that I should leave the aux shaft bearings undisturbed. They say that they are difficult to install but I can’t understand why. It seems that if you are competent to insert cam bearing in a v8 that you ought to be able to handle these. What’s the scoop? I really want to hot-tank the block which would, of course, ruin any bearings.

[Midwest124]

The Aux bearings really have no significant load on them and as such they rarely NEED replacing unless the engine was run w/out oil.... ouch! They are not difficult to install but most places do not have the reamers for them. They do need to be sized after pressing in (even the "pre-sized" ones) They are also quite difficult to find at most vendors... accept of course for me.. I have several sets available. $35 for the set + postage.

To be sized, a shop CAN use a brake cylinder hone and lightly size them to fit the aux shaft.

[So Cal Mark]

instead of hot tanking, find a machine shop that uses a high pressure water based cleaner. That won't damage the bearings at all and will clean extremely well

[bradartigue]

They are babbit bearings and really can't be bored or honed. They are not all that easy to align or ream, and sizing them is a bitch. If you absolutely must replace them then find them sized if you can. If they are in good shape then plan on simply cleaning the block (you can use a pressure washer and degreaser or just the degreaser and a sponge). FIAT actually recommends using soda and water (not sure what they mean by soda) and never mention "hot tanking."

I just rebuilt a 1438 by degreasing and blowing out the oil galleries with compressed air. It was then bored, honed, cleaned up, primed, and painted. We left the bearings in.

[Dales78]

Thanks for your help on this. I don't like the looks of my old bearings and have acquired a new sized set. I'll let you know how it all works out after the dust settles.

[racydave]

The clearance issue would be reflected by your oil pressure. If you had good pressure, then I would think they were probably good. Also since they bear little pressure, they wont look like bearings normally do... Before I put them in, i would check the dia of the shaft, and the ID of the bearing. good luck

[Dales78]

Thanks for the input Racydave. Unfortunately, this engine is of, uh, unknown origin since it was purchased used by the PO and never assembled (basket case). So, I have no idea what kind of oil pressure it may have run prior to disassembly. I'm going with my gut on those bearings. I guess we'll see how clever we are.

Thanks again.

[racydave]

Im with you on that, one thing to consider when fitting the surfaces, keeping a good centerline when reaming, or honing... still, would be nice to use a micromiter. How did the other bearings look???

[Dales78]

There was really nothing that I saw that looked outside of "normal wear". However, not all of the used bearings were included in my boxes of parts.