quietflyer

My Feedback: (1)

I bought a PAW 35 r/c recently that was advertised as NIB. I see a prop driver play of about 1/64". Is this common with PAW engines of this size? I own several smaller PAWs and they have very fine tolerences as far as crankshaft play.This engine turns fine and the compression is excellent. Is this amount of play a sign that the engine has been run before ? Will this play lead to accelerated wear or binding? What is the normally acceptable range of play for crankshafts? I look forward to your assistance in this matter. Thanks.

steve111

A bit of fore/aft shaft play is pretty common in plain bearing PAWs and is no real cause for concern. It's more surprising that your other engines don't seem to have it!

Diesel Fan

The 35 has a single race though Steve and I am surprised that it should have any play at all (apart from internal C bearing clearance) as it indicates that the crankshaft is sliding too easily in the bearing.

quietflyer

My Feedback: (1)

The engine wasn't advertised as a ball bearing model and neither BR nor TBR was stamped on the lugs, so I am assuming it is a plain bearing model. I wasn't sure about the acceptable range of end play with the prop driver and hence was concerned about excessive wear.

steve111

Chris, the 35 has been sold in PB, BR and TBR versions, so I'd assume that this is a PB one and the play is not abnormal.

Diesel Fan

If it is a plain bearing one mate then yes, play is normal but the PAW web site gives only BR models as current.

But as it seems to be indeed an older model I stand corrected.

P.S. Just went into my garage and checked both PAW TBR 40's - zero axial play, Super Tigre X 45 (TBR) zero play, MVVS 49's and 40's zero play but the old PAW plain bearing 16 and 15 about 1 mm end float and the same with my 3 Enya SS engines.

P.S. Off topic I know butdid you recently order the Enya rear exhaust 60 Pro mate? (My most coveted stunt engine and yes, I am jealous if you did!)

ffkiwi

1/64" is quite moderate fore and aft play for a plain bearing motor-I have some in my stable with fore and aft play of about 1/16". In any case PAWs are run at the works before dispatch in any case, so even a NIB PAW should have fuel residue present. Fore and aft play is not usually a problem unless (i) you are using an electric starter or (ii) operating the engine with a pusher prop. In normal tractor usage the thrust vector is forwards so fore and aft play is irrelevant.

ChrisM
'ffkiwi'

Mr Cox

On RC engines the crank will start to rock back and forth at low throttle settings (near idle) so you do not want let the crank pin the backplate, even if you're not using an electric starter. It is very easy though to just add a few brass shims behind the propdriver to get smaller play in the crank. 1/64" is perhaps a little large, half of that would be enough, there should always bee some play though on a plain bearing engine.

steve111

Plain bearing ones still listed here: http://eifflaender.com/techdets.htm

Any of my ballraced PAWs have no axial play, as you'd expect, but the plain bearing ones all have it to some degree. As ChrisM says, it's really not an issue.

(And yes, I did receive a nice new 61CXLR the other day. Don't really need it, but just couldn't help myself. )

Diesel Fan

Ah, the RC one - too attuned to CL stuff I see!

The 61, hope to hear how it goes mate, it seems to be a gem amongst the ruff.

steve111

Que? There's both CL and RC ones listed, PB and BR. Dunno what happened to the 35TBR though.

quietflyer

My Feedback: (1)

Thanks for all the replies. It certainly is reassuring to know that the fore-aft endplay is somewhat expected of a plain bearing engine. The engine was bought on *bay as NIB but had slight mounting marks on the lugs and was hard to turn over when I received it due to congealed castor. I noticed the play only after I had freed up the engine with WD-40. If I were to follow Mr.Cox's advice on adding brass shims, what is the best way to remove the prop driver and reinstall it?
Does anyone have links to pictures/video of PAW engines being serviced?
Min

ffkiwi

The PAW 35 plain bearing model prop driver simply fits on the shaft via matching tapers. If you have a hot air gun, try heating the prop driver (and try and keep the hot air jet localised on the prop driver) for a few minutes-this will expand it and it should loosen with a light tap. [You can also use a small butane torch-but the hot air gun is preferable] If your 1/64" was an accurate measure then you'd want no more than an .010" thick shim washer. There should be no requirement to strip the engine any further

ChrisM
'ffkiwi'



BTW end float is not just 'somewhat expected' to quote your words-it is essential! If there was no end float the engine would bind once it had warmed up, as the crankcase expanded.....

quietflyer

My Feedback: (1)

Thanks for the tip, Chris.

quietflyer

My Feedback: (1)

I missed that part about the end play! Makes sense now.

brokenenglish

Everything that Chris has written above is correct but, respectfully, why do you want to mess around with an engine that seems to me to be perfectly OK the way it is?
The initial question, at the beginning of the thread, was due to QF's thinking that the engine is BB but, having established that it's PB, then the engine is perfectly normal...
Imagine if every owner of a PB engine that has 1/64 of end-float on the shaft decided to dismantle the engine to pack out the end float... That would probably involve most of the PB engines in existence! and create a world shortage of thin washers!
Just accept that your engine is perfectly OK and that a little end float on a PB engine is perfectly normal.
Playing with the engine on the bench for an hour, and becoming familiar with it, will achieve a much more positive result that discussing the fixing of imaginary problems.