UKpatternflyer

I have just fitted a new front bearing to a YS 175 crankcase, fitted the crankshaft, drive washer retainer and the prop driver, then tightened up with a prop in position. Prior to tightening the crankcase span freely (well as free as it can be with crank ring fitted) but once I tightened it it became quite sticky to turn. I've re-assembled it several times to no avail. Has anyone any thoughts why this might be happening?

Thanks

Keith

kenh3497

It would be my guess one of the bearings not fully seated. Most likely the rear bearing. Heat the case and try to get the bearing to seat. I use a propane torch and fan the bearing area with the flame.

Ken

maustin

My Feedback: (7)

I would put the assy in the oven and heat up and then re-tighten. Might lightly tap with a rubber mallet around the bearing area of the case as you tighten. Agree with Ken rear bearing is prob not seated properly.

ELI Kats

My Feedback: (2)

Had the same with my YS-170.
Found out that the front bearing was not seated deep enough - there ware few tenths of mm to go.
I placed a socket (out of a socked wrench kit) , same diameter as the outer ring of the bearing, and tightened the prop washer over it. That way it pressed the bearing into its place.
Then placed the prop and it was OK.
Eli

UKpatternflyer

Thanks for your replies; I'm back home tomorrow so will have another look at this. I was pretty sure the rear bearing was in the right position as it was flush with the crankcase innards. The front bearing was pretty tight in the housing so perhaps that's the one at fault, although the gap between the back of the prop driver and the crankcase was very small when the prop was tightened into place. I'll let you know what happens

Thanks

Keith

apereira

Was there a washer between the drive washer and the bearing?

airraptor

My Feedback: (66)

Did you get it sorted out?

UKpatternflyer

Hi Apereira,

The assembly order is Oil Seal - front bearing - drive washer retainer - Drive washer (i.e prop driver). The oil seal sits in a recess and from the assembly diagram it is closed side forwards. I have tried it both ways and it didn't make a difference; the assembly still tightened up when I tightened the prop. I think I'm going to put a G clamp with packing onto the back of the crankshaft and to the front face of the front bearing (similar to what Eli did), and then put it in the oven etc


Hi Airraptor

Not yet; working away from home and Christmas stuff is really getting in the way of the important stuff to do. Hopefully get back to it by New Year


Have a great Christmas

Keith

drac1

My Feedback: (4)

Hi Keith,

I'm interested as to why you only replaced the front bearing? My experience is that the rear bearing is the one that always wears. The front bearing always feels OK, but I replace it every time I replace the rear one anyway.

It sounds like it's tightening up because the bearings aren't all the way home.

Scott

UKpatternflyer

Hi Scott,

I did actually replace the rear bearing bu the engine has been dismantled for well over a year now as I've been distracted by things electric! Hope to finish this after Christmas

All the best

Keith

kenh3497

My vote is the rear bearing is not seated completely. Heat the case with a torch and the bearing will drop right into place using the weight of the crankshaft. Many will say the torch is too aggressive but I feel getting a lot of heat quickly into a concentrated area will do less damage than general heat. In the end I feel less heat overall is used. You milage may vary.

Ken

apereira

Keith,

I have not taken apart my 175's yet, just went to the 185, but as I saw in the breakdown the washer I mention is not there, could it be the bearing oil seal?
The bearings you can clearly see if they are fully seated with the recess in the crankcase machining.
The drive washer conical adapter should seat on the inner racer of the front bearing giving the clearance, could it be that one of the parts is worn?
Really can't provide any more ideas.....

Regards

Alejandro

UKpatternflyer

All sorted now! I got the front housing hot, found a socket that was the correct diameter to engage only the outer ring of the front bearing and gave it a few taps of a plastic hammer. Now the crankshaft spins freely, especially after I snapped the crank ring removing the shaft! Doh

Thanks for all your help

Keith

airraptor

My Feedback: (66)

Glad you figured it out. On front bearings it only takes a little piece of dirt to keep the bearing from going in smoothly yet having you think its all the way in.