A couple of questions for the wrenches here regarding precision in maintenance tasks:

1. Replacing fork oil on my FLSTN called for 392 cc or 12.9 oz of oil. Those are pretty specific figures, so I got to wondering how precise one must be in adding the oil. What would be the effect of putting more/less oil in the fork -- e.g., a few cc's more or less?

2. I read a comment on another post that HD's torque specifications were generally too high. Looking at my service manual, torque specs are in some cases very broad (e.g., 18-24 ft-lbs, 30-45 ft-lbs, 144-180 in-lbs). When given such a broad range, how do you determine what to use? Personally, I tend to use a setting toward the lower end of the range, but sometimes wonder if that's tight enough.

 

Low end, high end or in between. It's all good.

 

Just went through this with a bmw ...called for 410cc in each leg... WRONG ...that was way too much yes it is pretty important to get the right amount in each leg but more important to get the SAME in each leg ..let the legs drain out for at least an hour better if overnight then go to a feed store or vet supply and get a large syringe ..I am using a 60cc one and just do them the same amount each ...even the bmw gave +- 10cc ...if too little you will bottom out if way to much you will have a ridgid front end
As for harley specs that depends on the diameter of the bolt and if it is going into cast ,cast alum, or steel interior engine bolts I do to the max steel to steel case bolts I shoot for middle of the span and smaller less important bolts I use the bottom of the scale ...and blue or red loctite as needed

 

Good info! I hadn't thought about the syringe, just used a graduated cylinder. And that seems to be a good process for logically choosing torque settings. Thanks!

 

Baby bottles have cc measurements as well.

 

Just how important is a torque wrench anyway?

 

Fork oil is more precisely measured as a distance to the top of the fork with the spring out and the tube compressed. The volume figures given although accurate can be affected by fluid remaining in the tube. The air space on top of the fluid and getting them equal is what is important. There is even a syringe made with a tube that has measurements on it so you can withdraw fluid and leave it the correct distance from the top.

 

SgtThump .. a tourqe wrench is used to measure the amount of force/tourqe being applied to a bolt/stud/nut fastner .it's use is very important when using mixed materials alum head/ steel cyl /and compression head gasket ..modern engines (car) use throw away fastners that are designed to stretch once and if taken off then disposed of ..all bolts stretch and that amount of stretch is controlled by the amount of torque applied ...
DCLXVI while a measurment is the ideal way to do it it is hardley ever practicle unless you want to completly strip the top end of the forks that is why you leave it drain overnight to get as much out of the forks as possible working them to the limits also helps ...and yes getting the same in each is really important but if you drain a set in seperate pans and compare how much was in each quite often they are signifigintly different ...........and I use the syringe cause it is easier to load and has a nice tapered end on it to put on a hose

 

Perfection is a waste of time. Close enough has worked well for me over my lifetime.

 

That's true (could have gotten one of those from my daughter if I'd thought of it earlier) and even the fork oil bottles have a graduated oz / cc scale on the side, so you could just interpolate between the marks to get the required volume.