input gear shaft.

[saab900aero]

gday all, i have just pulled apart my gearbox and found that the input shaft (the one with the small gear machined into it) has a bit of an uneven pitted end. its the end that sits in the needle bearing. i know this has to be near perfect to last otherwise it will chew the needle bearing out. has anyone ever heard of repairing these??? someone says they may be able to metal spray it then machine it??? has anyone ever heard of this?? or is there another way to clean this shaft up??

cheers alex

[IdahoCharley]

You can have many machine parts built up with metal spray and then machined down - problem is that for what YOU are talking about you could likely buy a number of new ones for the cost of having a single item built up and then machined to specs.

I did have a couple of corvette wheel spindles built back up using a metal spray process a few years back for about half the cost of new but no remachining was involved and I was dealing with a company specializing in corvette repairs and I was buying 4 speciality brake calipers from them at the same time.

In my experience metal spraying is used to build up worn industrial shafts, rollers and speciality molds which initally cost in the thousands. It is also used for rebuilding some relatively high demand items in the automobile industry. Metal spray coating and metal spray forming have come along ways in the last 15-20 years but there is still a significant amount of time spent in the set-up and proper application of a metal spray coating process.

I THINK what is going to be the problem for you is just the fact that you have a small single shaft and by the time it is machined surfaced clean and then set-up in the metal spray application machine and sprayed the time factor for each step is going to be costly dollar wise. If done improperly you can end up with a surface coating that will flake off and in your case destroy your bearing.

IMO you should take your shaft to a performance machine shop and get a professional opinion. A few pits pockets should not be hard on a needle bearing.

P.S. Is there a possiblity that the shaft could be turned down slightly and a needle bearing with a slightly smaller ID but the same OD installed? A good performance machine shop can likely answer this question for you also.

[kawagumby]

You'd probably be better off buying a new shaft. The needle bearing are under a lot of stress, I've had them fail (high time) with a good shaft. If a jerry-rigged repair begins to fail, you'd likely not be aware of it until something really expensive happens.