1977 Ford F250 sector shaft spray welding

My 1977 Ford F250 power steering box is a bit loose on the bottom sector shaft journal. This was a $350.00 "rebuilt box" but it looks like the only thing rebuilt about it was a resealing job. I opened it up and the main issue seems to be the lower end of the sector shaft, (nominal 1.375 dia), is worn about 0.003" and the housing bore is ovaled out about 0.015". The sector shaft on this box has no bottom bushing or needle bearing. I'm thinking about boring the housing for a Torrington needle bearing. The sector shafts are no longer available, so it will need to be repaired.

By strange coincidence I found a Eutectic Rototec spray welder kit new in the box on Craigs list today. It came with with a supply of unopened spray powders. It's more or less a oxygen/acetylene torch with a feed hopper and a tool post mount setup for for spray welding. According to the manual, the Rototec process is a "cold" process that does not heat the shaft over 500 F, I'm thinking about using it to build up the worn journal area on the shaft. One of the powder formulations is recommended for build up of bearing races, so it sounds possible. The other alternative is bushing the housing with a bronze bushing. This would have lower unit loading than a needle bearing on the shaft overlay. Comments?

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I used one of those Rototec spray welder's a lot when I was Chief Engineer of a brewey in Fiji.( about 30 years ago) It used to get us out of a lot of bother. We used it mostly on pump shafts that had packed glands instead of mechanical seals. The gland area of the shafts wore badly over time. We sprayed them up with a powder that had ( if I remember correctly) silicon carbide in a nickle matrix. They were as hard as the devils toenails and lasted far longer than the original shafts. I think we also used it on shafts where the bearing inner had turned on the shaft and we also used it on an air compressor crankshaft where a main bearing journal had worn undersize. It performed well on all those occasions, but I don't recall ever using it on a roller bearing, where the roller ran directly on the shaft, so I can't really give personal experience advise on that.

two things I do remember is :

1) cover up the bed of the lathe really well. The powder is abrasive as hell.

2) There should be some temperature crayons in the kit. Use them, and DON"T let the shaft get over the recommended temperature or it wont "stick "well, and the shaft could take on the shape of a bananna

Good luck

PS you will have to grind the shaft after spraying asthe stuff can be hard to get a decent finish on with just a carbide tip.

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Got a U-Pull-It around? Could be a LOT cheaper than tooling up for a one-off.


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I've got a similar issue with my power hacksaw. On the cutting stroke it makes a "bonk" noise (only when actually cutting; the machine is almost silent when running without cutting). I took everything apart. The only cause I can find is 0.027" clearance between the bronze bush in the final pulley (which also acts as a flywheel and crankshaft) and the supporting shaft (the figure is the total, i.e., the sum of the wear on the bush and shaft diameters). The shaft has a nominal diameter of

1.250". The wear is almost all in the direction of the belt pull, which is perpendicular to the motion of the hacksaw bow. I was surprised to find that 0.027 was enough wear to make a loud noise when the pulley only turns at 100 or 150 rpm (the machine has two speeds). Unless there's another cause for the noise, but I can't find it.

Most of the wear (0.024") is on the shaft. The bush has much less (0.003"). I imagine the bush has been replaced many times. So there's little point replacing the bush. The shaft is no longer available as a spare part, and would be hard to make as it has oil channels through the centre. So one option would be to build up the shaft somehow (not something I'm thinking of doing myself). There's a little scoring on the shaft. I considered trying to polish out the scoring, but I'm not sure how. As the machine works fine, I'm inclined to ignore the bonking noise. I don't want to do more harm than good.

Do you mean that the centre of the shaft doesn't get hotter than 500 F? Surely the surface has to get hot enough to melt the steel?

Best wishes,


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Christopher Tidy

Actually not, as Grumpy mentions Eutectic provides a 200F and a 500F surface marking crayon for the shaft to be repaired. The procedure calls for maintaining the surface temp between 200 and 500 F. A bond coat is used first, then one of several top coating alloys. They refer to it as a cold process. Some of the powders are exothermic according to the literature, but the base metal does not get very hot.

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Seems like a good idea, but the housing might start to get questionable if I remove enough to make room for the added wall of the hardened ring. Meanwhile I think I found a good sector shaft that won't require building up.

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