ISX crankshaft gear

[Rawze]

(09-08-2023 )KCMshop Wrote:  ...
Yea removal was no problem. I wonder if i need to heat it hotter then the 350F specified in Quick serve.
Thanks for the reply.

350F for a press-fit gear of that size actually does seem like it would be barely enough when I think about it. I know I have had to heat gears that size to the 475 - 500+F range in the past other industrial equipment. Depends entirely on the clearances and/or if the shaft is to be cooled too.

There is a general rule however in interference fit components that .. At or above 600-F, and you will start to soften the metallurgy just enough to start to cause warping, even for harder metals.

Also.. the component needs to be very well evenly heated, meaning that you cannot do it with a torch or other external means,.. but using an oil bath(up to 350-F max, or the oil will burn) and the part NOT sitting on the bottom of the container ... or in an oven with racks for a few hours if heating something above 350-f.

Many instruction manuals for interference fit gears will have statements like ... "Open Flame Heating is not recommended" as uneven heating will cause warping too, as it is almost impossible to heat the gear perfectly with a torch, and it not end up warped on the shaft after it cools.

------
(from back in the days when I had to deal with this kind of stuff in the industrial world) ...
As a coarse/service-man's rule of thumb on stuff that is below about 24" in size, at 350-F (a common industry standard temp for installing for interference fit gears) ... for every 1.100-inch of inner diameter of the gear in total, there typically would be roughly about 0.001" of interference.

Someone could do the math on the inner diameter of the gear vs. the shaft diameter, and determine if the interference amount matches up roughly with the 350-F rule of thumb or not.

Also, the tighter the negative clearances on the gear, the hotter you must make it (and the colder the shaft must also be), before it fits properly. But also... the gear itself AND the crankshaft in this case, has to be perfectly clean and polished too, so if there is any scars, dings, deformations, residues, anodizing, etc. on either mating surfaces then the clearances will not match up to the temperatures recommended.

I/E.> That 350F temp rating might only be for brand new parts, and not parts that have a lot of miles, age, etc. on them and are not perfectly polished any more.

Thorough polishing with scotch-brite pads + acetone after removing any dings, scars, etc.. is the way to get the inner and outer surfaces prepped.