Bolted to my damper is a drive mandrel, one inch diameter shaft, about five inch of shaft in length. The shaft is keyed. The fuel injection pulley is closest to the damper, then the dual drive pulley is next. I had it made out of aluminum, with a four inch diameter groove for the vacuum pump belt, and a three inch grove to drive the alternater. There is an extension about a half inch wide and 1.950 diameter on the outside of the pulley. Today i discovered it is loose on the shaft. So how can i fix this? I believe it will need a good press fit to hold up in the future.

I'm not understanding exactly what is loose and how is it loose? Is it just a spacer? Can it be shimmed tight? Is it loose on the piloting diameter? etc pics will help

I don't understand either. From your description this is what I think I understand you have. The dual pulley is loose. How are the two pulleys locked to the shaft now? I realize you said they are keyed but how are they locked?

6pak your drawing shows the type of mandrel I have, the pulley is a one piece, dual grove unit, keyed and set screw. I assume since it was a slip fit at room temp, it started to wear from the torsional vibrations that are present in the crank snout, which caused wear to loosen it up on top of what it would grow as it got warm. The shaft is 1.00 inch diameter, and the pulley is now probably 1.002 cold, worse as it warms. I am guessing I will find a damaged keyway in the aluminum pulley as well. What I am wondering is, can I get some shim stock or a thin sleeve, hone the pulley oversize to accept the sleeve by heating it up in an oven, then install the sleeve pre notched for the keyway, and if I do this right, it will need a slight press fit at say 300 degrees pulley temp?

I just reached in and could feel the keyway in the aluminum pulley has been seriously enlarged. The bore in the pulley feels like more than .002 bigger than the mandrel.

A slip fit for a 1" shaft should have no more than 0.002" clearance which I assume is what you started with based on your comments. So if the bore of the pulley is 1.002 and the shaft is 1.000, you still have acceptable diametrical clearance and the "play" you feel is rotational, not radial. If you are losing your tolerance on the pulley keyway, yes, you can sleeve the pulley with a steel insert with a new keyway and grub screw the two together. Or go the the next largest key/keyway. Or have a new pulley made of steel. I'd talk to a competent machinist and see what their comments would be. Good luck.

Agree that .002 loose is still acceptable. Jones has always been great for me with a variety of pulleys if that's all you'll need. I locktite the set screws.

I should get time to pull it apart later today. To be more clear, that keyway slot in the aluminum pulley has been hammered by harmonics to the point i bet it is now .030 or more too big. I can rotate it on the mandrel shaft at least that much. What i want to do is figure out how to get this thing fixed with it having a press fit, just like the damper. Since the mandrel bolts to the hub of the harmonic damper, it is still recieving the bad vibes the damper is meant to calm.
So maybe the best route is bore the pulley out oversize, install a steel sleeve with a press fit, then hone the inside of that sleeve for a press fit, and cut a keyway slot. In addition, maybe a roll pin as well.

Pics-
I talked to Loctite and they suggested 638 green, if i feel the need for something to add grip beyond a pressfit.
My problem is the shaft measures .999, and the pulley measures 1.001, both at room temp. Sooooo, how to come up with a plan to end up with a press fit?

can you knurl the shaft

my thinking is the aluminum might not stand up to that.

Put the pulley in a lathe and bore it out to an 8° taper of the appropriate size to fit a taper lock bushing. That will hold it

https://www.mcmaster.com/products/bushings/bushing-type~taper-lock/shaft-diameter~1/

Maybe drill and tap the end make some spacers to hold everything in the correct location. Make the last spacer so it sticks out farther than the end of the shaft tighten with a bolt and thick washer then lock the set screws. That is how mine is and seems to work good.

I would question the use of a rectangular key in that application. If you have torsional vibrations, a rectangular key tends to "rock" in the keyway and beat the keyway up. I'd seriously consider using a Woodruff key. As to restoring the fit in the pulley, you only have so many options for a press fit....new pulley or an insert in your current pulley. The 638 may be an option, from the TDS it appears to be a reasonable choice.

Yeah that's where I was going too. Not that what you have won't work but looking at it I have a lack in confidence in the run-out of the assembly and I'd chuck it up to gage run-out first. Then again you can knurl for a fit etc. Definitely add spacers as mentioned and sandwich everything tight.

All of those ideas will work. But if you don't the the equipment to do some of those. Jones Racing Products has what you need on the shelf.

After seeing all the welds on that mandrel, if there is any wobble at all on that shaft, it will cause all kinds of problems w/ the pullies.
I had issues w/ an Aerospace components mandrel. The shaft was tweaked, not visible w/ the naked eye while running. Caused the pullies to gall up and move around.

If it were me I would be looking into a new mandrel....Lots of options out there.

I spotted this, but info is a little vague, and if I fix this problem, i don't have to spend the $$. I have shim stock ordered, had the pulley honed to oversize , will have an interferance press fit of .0015 plus the key to hold the pulley tight.

The mandrel is originally a Moroso piece, and the plate with the weld on the circumference is actually two pieces that I welded together so the shaft could be tacked in place on a lathe, then the register for the spacer had weld added and was machined for a proper fit. So there is only enough slip fit to the spacer , better than originally done by moroso. It may look ugly, but the welding is solid, runout near zero. So I am not worried about the mandrel itself. Tomorrow I will get some dry ice to cool the mandrel, heat the pulley, and try and put the thing together. According to specs for metal expansion due to tempurature change, at room temp max interferance should be around .0016, failure is .002, I am set up for .0015 interferance fit, using .004 shim stock around the shaft. As it warms from engine heat, that fit will loosen to about .0008. i have 638 green locktite as well, which i will apply to the keyway after assembly. I don't know how the cold will affect the 638, but tech told me heat will definately speed curing, so i am hesitant to use it on the shaft and shim material .