Radial Drive Wheel/Shaft Tolerance

[rognvald]

I am replacing my Edson 800-8 Radial Drive Wheel which has suffered from galvanic corrosion after 24 years. The drive wheel is anodized aluminum and the rudder shaft is stainless steel tube--3/8" thickness. The drive wheel is a two piece split construction with a 1/4" stainless bolt through the shaft and 1/4" bolts that connect the two pieces. The "off the shelf" ID of the radial drive is 2.860". The OD shaft measurement is 2.850". Is .010" critical in this split installation for maximum mechanical integrity? Are there any serious drawbacks if the tolerances are not exact? If so, what? All responses will be greatly appreciated.

[model 10]

Are you talking about the quadrant? If so I would want it to be tight, not loose. I would be tempted to take some material off the mating surfaces so they just barely touch. I would not want a .010 loose fit on the rudder shaft, maybe .003 tight as a min.

[rognvald]

Originally Posted by Guy

Are you talking about the quadrant? If so I would want it to be tight, not loose. I would be tempted to take some material off the mating surfaces so they just barely touch. I would not want a .010 loose fit on the rudder shaft, maybe .003 tight as a min.

Guy,
I think we speak a similar language but I was duly informed by Edson that it is not a quadrant, as you and I have called it for years, but a radial drive wheel. So much for nomenclature! So, the issue then would be that you would not have even compression, 360 degrees, on the shaft but rather an unevenly loaded compressive force? Ergo, a weaker installation? Greater propensity for failure?

[colemj]

Have you talked with Edson about this? If you are replacing with the exact same model, and are using the same shaft, how would the new one be different?

Mark

[model 10]

Originally Posted by rognvald

Guy,
I think we speak a similar language but I was duly informed by Edson that it is not a quadrant, as you and I have called it for years, but a radial drive wheel. So much for nomenclature! So, the issue then would be that you would not have even compression, 360 degrees, on the shaft but rather an unevenly loaded compressive force? Ergo, a weaker installation? Greater propensity for failure?

Of course you are right but it would be the lesser of two evils. You should get it honed back to round for sure. You might be surprised how little it will take. The radial drive wheel will have some flex when you tighten up and I think would still fit pretty good without honing . You could do the fitting yourself with common tools if need be.

[rognvald]

Originally Posted by colemj

Have you talked with Edson about this? If you are replacing with the exact same model, and are using the same shaft, how would the new one be different?

Mark

Mark,
I have spoken extensively with Edson and they make a few "off the shelf" sizes but highly recommend re-measurement of the shaft with a micrometer (which I have done) since they claim the tolerances should be as small as possible to insure a solid installation. Ergo: 2.850." My old quadrant/radial drive was probably the standard 2.860" and I doubt Pearson had an exact match to the shaft being a production builder. I want to get it right/better since it will undoubtedly be the last time I will undertake this repair.

[rognvald]

Originally Posted by Guy

Of course you are right but it would be the lesser of two evils. You should get it honed back to round for sure. You might be surprised how little it will take. The radial drive wheel will have some flex when you tighten up and I think would still fit pretty good without honing . You could do the fitting yourself with common tools if need be.

Guy,
Yes, that would be possible but the wheel hub has been destroyed by galvanic corrosion where the stainless through-bolt passes through the quadrant's collar(I hope Edson forgives my terminology). Therefore, I must by new.

[darylat8750]

I would take enough off the wheels mating surfaces to make it an obious interference fit then coat the shaft with valve grinding compound and hand lap it to a light interference fit. That should give nearly 100% contact between the parts. Use something like Boeshield t9 to keep corrosion to a minimum.

[Blue Stocking]

Am I reading something different from what you guys are reading ? The rudder stalk is 2.850, the radial drive is .010 larger, so the fit is sloppy. I would have the wheel line-bored to 3.000+, and bushed back to the shaft size. Plug weld the bushing in place, and line-bore to 2.850.

[colemj]

Originally Posted by Blue Stocking

Am I reading something different from what you guys are reading ? The rudder stalk is 2.850, the radial drive is .010 larger, so the fit is sloppy. I would have the wheel line-bored to 3.000+, and bushed back to the shaft size. Plug weld the bushing in place, and line-bore to 2.850.

It is a split radial drive - two halves.

Mark

[rognvald]

Thanks everyone for the great feedback. I have ordered the radial drive wheel through Defender for $366. plus $112. for special boring through Edson. I had the drive bored to the exact OD dimensions of the shaft: 2.850" and hope it will be a solid installation. I also ordered two split shaft collars(same dimension) with a special set screw for the rudder shaft where it exits the upper and lower shaft tube. I will check alignment of the upper and lower bearings with a mock prototype shaft made of a dowel rod and two discs before installation since there was some damage to the upper rudder tube/bearing from the PO that I am repairing. The saga continues.

[model 10]

Did they say to bore it to the exact same size? I would have thought you would want the Quadrant to be tight on the shaft? With it being a completely split collar, not a very long keyway and all. Maybe like .001-.003 tight. Especially on a worn shaft.

[rognvald]

Originally Posted by Guy

Did they say to bore it to the exact same size? I would have thought you would want the Quadrant to be tight on the shaft? With it being a completely split collar, not a very long keyway and all. Maybe like .001-.003 tight. Especially on a worn shaft.

Guy,
Edson said to bore it to the exact OD of the rudder shaft. It does not use a keyway but is through bolted with a 3/8" pin(bolt/washer/lock nut). Perhaps the shaft is slightly worn since the factory pre-made drive wheel was machined to 2.860". I would imagine with the dissimilar metals--aluminum and stainless, there must be some expansion/contraction based upon temperature and humidity so an exact tolerance(shaft to metal) should be good. What do you think?

[model 10]

They must know. You must have used a micrometer to measure in several places and took the smallest measurement? Any chance it's a tapered pin through bolt? They are by far, the best way to do what you are doing. They pretty much never come loose

[rognvald]

Originally Posted by Guy

They must know. You must have used a micrometer to measure in several places and took the smallest measurement? Any chance it's a tapered pin through bolt? They are by far, the best way to do what you are doing. They pretty much never come loose

Guy,
When I measured the shaft with my micrometer, the overwhelmingly number of readings were 2.850". I did, however, get some readings that were marginally less but not consistently so. I was told that since the shaft is hollow, ergo a stainless tube, the dimensions would not be as precise as a solid shaft that was turned on a lathe. The pin supplied by Edson is not tapered but a standard bolt. It was difficult to determine the exact bore of the old wheel since it suffered from galvanic corrosion around the bolt holes. The beat goes on . . . with fingers crossed.