TT 40Pro endplay?    Gallery
View related threads: (in this forum | in all forums)

Logged in as Guest



Users viewing this topic: none
    Search This Thread  
 
Printable Version

All Forums >> RC Airplanes >> Pylon Universe - RC Pylon Racing >> Q-500 Racing >> TT 40Pro endplay?
Page: [1]

Tower Hobbies Get Coupon Codes Brands  
Login
Message << Older Topic   Newer Topic >>
TT 40Pro endplay? - 10/15/2011 3:56 PM   
GSJames



Posts: 435
Score: 100
Joined: 11/11/2003
Last Login: 5/24/2013
From: Weatherford, TX, USA
Status: offline 		In August, I blew a rear bearing in my 424 engine. I foolishly didn't realize that it had the old style rear bearing (lesson learned). At the time it was a very good engine, peaking at about 17.2-17.3 on an APC 9-6. In rebuilding it, I replaced the Piston/Liner, cleaned up the head and of course the bearings. I replaced both bearings with a set from RCBearings.com http://www.rc-bearings.com/catalog/product_info.php?cPath=65_66_77&products_id=748

Prior to the rebuild the engine had noticeable endplay. Now it does not. I even bought a bearing seating tool from Darrol Cady and re-set them again. The bottom end is very free, and the crank rocks back and forth nicely. I have about a gallon of 15% through it at this time and 4 heat races. It was re-broken in on an APC 8-7 running rich at between 16.8 and 17.3K and then with a 9-6 at best mixture. The engine seems fairly strong, though not a world beater. HOWEVER, as the engine heats up, it slows down noticeably. For the first minute after starting, it will run strong at about 17-17.2 and then as it heats up more, it will slow down to 16.7 or so. I noticed this during the heat races as well, it started out well but slowed down as the race progressed.

The RC Bearings replacement front bearing is listed as being .281 inches wide, Tower shows the stock front bearing as .28 wide. http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXAHZW&P=ML There is also text saying that it is 7mm wide. According to my conversion program, 7 mm is 0.2755906 not .281.

Since the coefficient of linear thermal expansion of aluminum (the case) is almost twice what it is for steel (the crank), it is possible that I am getting a bind as the case heats up and that it is what is causing the engine to slow down?

Other than buying a stock replacement front bearing from Tower, I can't think of any "legal" solution to this problem (it's not legal to mill out the front bearing recess). Any thoughts on other ways to fix this? Thanks!

_____________________________

Gary James
AMA CD 68845, NMPRA 15I, RCCA #908

Hide Signatures
       Post #: 1

RE: TT 40Pro endplay? - 10/15/2011 5:31 PM   
HighPlains


 

Posts: 4597
Score: 152
Joined: 3/2/2003
Last Login: 5/24/2013
From: Over da rainbow, KS, USA
Status: offline 		Gary,

I would go back to the stock front bearing, since it's failure should not cause the type of engine destruction that failure of the rear bearing will cause.

When everything has proper clearance, the rear bearing has all the axial thrust loads, while the front bearing is floating. The difficultly is the expansion coefficients of steel and aluminum as you noted, so it should be set up for running conditions. Pop it in the oven at different temperatures (under 200 degrees) to check the end play. If the bottom end is running hotter than that, you have other problems.

_____________________________

- Supplementary insipid innocuous inane vacuous proclamation

Hide Signatures

(in reply to GSJames)
       Post #: 2

RE: TT 40Pro endplay? - 10/15/2011 8:08 PM   
bigtrev@xtra.co.nz


 

Posts: 319
Score: 100
Joined: 9/25/2004
Last Login: 5/21/2013
From: christchurch, NEW ZEALAND
Status: offline 		have to agree wth the previous reply.....reseat the bearings, the problem is most certainly in the bottomend. and also check the clearance type of bearing- C1,C2, C3, etc. Darol's bearing tool is very good but you have to know how to use it. trevor Henderson, nz

Hide Signatures

(in reply to HighPlains)
       Post #: 3

RE: TT 40Pro endplay? - 10/15/2011 11:36 PM   
djlyon



Posts: 2492
Score: 100
Joined: 12/11/2001
Last Login: 10/3/2012
From: Castaic, CA, USA
Status: offline 		Gary your description of the problem does not suggest milling the front bearing seat. It sounds like you need a shim between the crankshaft and front bearing inner race. Or maybe there was a shim there and you forgot it when you reassembled the engine. Now when you tighten down the prop nut you squeeze the inner races of the bearings toward each other which is the worst kind of no end play.

Denis

_____________________________

I never met an engine I didn''t like.
Of the things I''ve lost I miss my mind the most.

Hide Signatures

(in reply to bigtrev@xtra.co.nz)
       Post #: 4

RE: TT 40Pro endplay? - 10/16/2011 12:08 AM   
GSJames



Posts: 435
Score: 100
Joined: 11/11/2003
Last Login: 5/24/2013
From: Weatherford, TX, USA
Status: offline 		Thunder Tiger 40 Pro engines do not have shims on the crankshaft. That is one of the first things I looked for.

_____________________________

Gary James
AMA CD 68845, NMPRA 15I, RCCA #908

Hide Signatures

(in reply to djlyon)
       Post #: 5

RE: TT 40Pro endplay? - 10/16/2011 3:46 PM   
jaka


 

Posts: 7183
Score: 158
Joined: 12/11/2001
Last Login: 5/24/2013
From: Upplands Vasby, SWEDEN
Status: offline 		Hi!
Try C4 bearings from Swiss company WIB (same used in Nelson and Jett engines) or reheat the case and see if the play returns.

Attachments
Click to see fullsize image.
Click for fullsize 		Click to see fullsize image.
Click for fullsize


_____________________________

Jan Karlsson - Supplier MVVS Products

Hide Signatures

(in reply to GSJames)
       Post #: 6

RE: TT 40Pro endplay? - 11/8/2011 2:41 PM   
GSJames



Posts: 435
Score: 100
Joined: 11/11/2003
Last Login: 5/24/2013
From: Weatherford, TX, USA
Status: offline 		I received a new, TT-branded front bearing. It mikes out exactly the same as the after market bearing so, unfortunately, that wasn't the problem. Oh well.

_____________________________

Gary James
AMA CD 68845, NMPRA 15I, RCCA #908

Hide Signatures

(in reply to jaka)
       Post #: 7

RE: TT 40Pro endplay? - 11/8/2011 6:51 PM   
Scorpion Racing



Posts: 603
Score: 105
Joined: 1/22/2006
Last Login: 5/24/2013
From: Lake Wales, FL, USA
Status: offline 		Gary, I have had issues with some of my Thunder Tiger PRO 40's doing this same thing. In my case, it was the tapered drive washer sliding down the crankshaft bolt and not locking tight. What I did was take a thin strip of .014 Mylar sheet and place it under the tapered nut before tightening the prop down. I then wiggled the prop back and forth and tugged on the Mylar till it cam out. It took a couple of times, but I eventually got it.

Another method is to tighten the prop nut and prop down good, and give the prop nut a solid tap with a hammer. this should knock the crankshaft back some, but still leave it tight. Be sure to use a prop nut you don't care about if you try this, because it will end up with a flat spot on the tip. I am sure you realize this could potentially damage the engine, but I know you are smart enough to know that!

Best of luck...

_____________________________

Scott Smith
NMPRA 86t - District 7 VP

Hide Signatures

(in reply to GSJames)
       Post #: 8

RE: TT 40Pro endplay? - 11/8/2011 7:43 PM   
jaka


 

Posts: 7183
Score: 158
Joined: 12/11/2001
Last Login: 5/24/2013
From: Upplands Vasby, SWEDEN
Status: offline 		Hi!
You should not replace the TT bearing with just any bearing!!!
The bearing to use is from the swiss company WIB! It's a C4 bearing with plastic retainers!
That is the bearing sold by Dave Shadel and that is used in all Nelson and JETT engines.


_____________________________

Jan Karlsson - Supplier MVVS Products

Hide Signatures

(in reply to GSJames)
       Post #: 9

RE: TT 40Pro endplay? - 11/8/2011 9:06 PM   
fizzwater2


 

Posts: 2520
Score: 124
Joined: 8/16/2004
Last Login: 5/24/2013
From: Paola, KS, USA
Status: offline 		I have had excellent luck and good performance with the bearing from RC-bearings.com. It's the correct size, with a plastic retainer, and costs a whole lot less and is easier to get.

I've been buying the stainless ones, but might switch back to regular old steel.



_____________________________

No matter where you go, there you are!

Hide Signatures

(in reply to jaka)
       Post #: 10

RE: TT 40Pro endplay? - 11/8/2011 9:51 PM   
jaka


 

Posts: 7183
Score: 158
Joined: 12/11/2001
Last Login: 5/24/2013
From: Upplands Vasby, SWEDEN
Status: offline 		Hi!
It,s vital that you get a lose fit bearing (C3 or C4)! Not an ordinary standard steel bearing! C3 or C4 means that the play between the balls and the inner and outer surface is less than a standard bearing...that means that the bearing produce less friction then a standard bearing.


_____________________________

Jan Karlsson - Supplier MVVS Products

Hide Signatures

(in reply to fizzwater2)
       Post #: 11

RE: TT 40Pro endplay? - 11/8/2011 10:20 PM   
fizzwater2


 

Posts: 2520
Score: 124
Joined: 8/16/2004
Last Login: 5/24/2013
From: Paola, KS, USA
Status: offline 		Last time I looked at performance specialties website, I didn't see any bearings for sale. Do you have knowledge of any other US sources for the Swiss bearings?


_____________________________

No matter where you go, there you are!

Hide Signatures

(in reply to jaka)
       Post #: 12

RE: TT 40Pro endplay? - 11/9/2011 12:50 AM   
djlyon



Posts: 2492
Score: 100
Joined: 12/11/2001
Last Login: 10/3/2012
From: Castaic, CA, USA
Status: offline 		http://aeroracingengines.com/

Is the current manufacture of the Nelson engines. The rear bearing is the same. I am not sure about the front bearing.

Denis

_____________________________

I never met an engine I didn''t like.
Of the things I''ve lost I miss my mind the most.

Hide Signatures

(in reply to fizzwater2)
       Post #: 13

RE: TT 40Pro endplay? - 11/9/2011 1:20 PM   
GSJames



Posts: 435
Score: 100
Joined: 11/11/2003
Last Login: 5/24/2013
From: Weatherford, TX, USA
Status: offline
quote:

ORIGINAL: Scorpion Racing: In my case, it was the tapered drive washer sliding down the crankshaft bolt and not locking tight.


Scott: THAT is EXACTLY what is happening. I'll try your trick. Thanks!

_____________________________

Gary James
AMA CD 68845, NMPRA 15I, RCCA #908

Hide Signatures

(in reply to Scorpion Racing)
       Post #: 14

RE: TT 40Pro endplay? - 11/9/2011 7:10 PM   
djlyon



Posts: 2492
Score: 100
Joined: 12/11/2001
Last Login: 10/3/2012
From: Castaic, CA, USA
Status: offline 		It is a trick and it might work but it is not the right answer. If the tolerance buildup between the crankshaft and the crankcase is such that the inner race of the front bearings end play is used up and the inner race is pulled tight against the balls by the Colet then the only good safe answer is a shim between the crank shaft and the inner race of the bearing even if you have to make one.

Denis

_____________________________

I never met an engine I didn''t like.
Of the things I''ve lost I miss my mind the most.

Hide Signatures

(in reply to GSJames)
       Post #: 15

RE: TT 40Pro endplay? - 11/10/2011 5:16 PM   
lfinney


 

Posts: 812
Score: 105
Joined: 2/19/2008
Last Login: 5/24/2013
From: kuna, ID, USA
Status: offline 		the higher the c rating on bearings the looser the fit......a thorough cleaning of the bearing surface of the crank at the rear bearing area is vital, i use 1000 grit wet or dry paper with water or wd-40 to polish and clean the bearing area on crankshafts, and then make absolutely sure that the case is clean..., i also polish the front bearing area of the crank as well, then check the fit of the bearings, if they take alot of force then the clearings will tighten up during assembly. i have had fellow modelers ask me to examine their engines after a bearing change, and they often fail to properly seat the rear bearing, resulting in zero endplay and also they have some tension as well, by reseating the rear bearing it usually produces some slight endplay at room temp, if the engine has no endplay at running temps thats bad.. i always reseat thunder tiger/magnum/supertiger engine before running.. if you cant find the WIB swiss bearings the plastic retainer types with a C3 clearance will work well too, they come stock in most OS and YS heli engines FWIW


Hide Signatures

(in reply to djlyon)
       Post #: 16

RE: TT 40Pro endplay? - 11/21/2011 3:15 AM   
SmokinJoe



Posts: 149
Score: 100
Joined: 8/20/2002
Last Login: 2/25/2012
From: HamiltonQueensland, AUSTRALIA
Status: offline 		This subject is dear to my heart, as Big Bruce will testify. I've grappled with this problem on and off since I started running the TT engine. Most of the time, you just tighten the prop nut gently against the prop, remove the prop and give the crank a light tap with a mallett, which moves the crank a few thou in the collet and there is your end play.

However, sometimes the collet then slips on the crankshaft when the prop nut is retightened. Sometimes I've swapped the collett and fixed the problem, sometimes a different crankshaft fixes the problem, sometimes even washing everything in alcohol to remove all traces of lubrication between the collett and shaft. Sometimes nothing I try will stop the collett slipping.

I must admit that I have not yet tried the shim trick. However, even with a shim between the shoulder on the crankshaft and the back of the front bearing, if the collett is slipping, you will still tighten the collett hard up against the bearing - which then compresses the front bearing - while leaving clearance between the rear bearing and the crankshaft.

If anyone has found a bullet proof way of preventing the collett from slipping, I would like to hear it.

Smokin Joe


_____________________________

Joe Luxford
Hamilton

Hide Signatures

(in reply to lfinney)
       Post #: 17

RE: TT 40Pro endplay? - 11/21/2011 5:55 AM   
djlyon



Posts: 2492
Score: 100
Joined: 12/11/2001
Last Login: 10/3/2012
From: Castaic, CA, USA
Status: offline 		think about it. With the correctly sized shim the collett will go hard against the bearing inner race which will go hard against the shim which will be hard against the shaft shoulder without PRE loading the bearings AXIALY. A properly installed collett should be hard against the inner race of the front bearing. You should not depend on the colletts grip on the crank shaft to do any thing but prevent the prop and drive hub from rotating on the crank shaft.

Denis

< Message edited by djlyon -- 11/22/2011 5:20 AM >

_____________________________

I never met an engine I didn''t like.
Of the things I''ve lost I miss my mind the most.

Hide Signatures

(in reply to SmokinJoe)
       Post #: 18

RE: TT 40Pro endplay? - 11/21/2011 5:01 PM   
jaka


 

Posts: 7183
Score: 158
Joined: 12/11/2001
Last Login: 5/24/2013
From: Upplands Vasby, SWEDEN
Status: offline 		Hi!
Remember that the front bearing is only taking axial loads (forward load)! That means the crankshaft is actually hold by the front bearing surfaces!
The rear bearing is only taking radial loads (the piston pounding up and down).

_____________________________

Jan Karlsson - Supplier MVVS Products

Hide Signatures

(in reply to djlyon)
       Post #: 19

RE: TT 40Pro endplay? - 4/25/2012 5:04 PM   
kommander


 

Posts: 61
Score: 100
Joined: 12/20/2005
Last Login: 5/24/2013
From: Newman, CA, USA
Status: offline 		I can't believe this post died with so much mis-information! The only one that is correct is dlyon.

Hide Signatures

(in reply to jaka)
       Post #: 20

RE: TT 40Pro endplay? - 4/25/2012 8:10 PM   
racerxwest


 

Posts: 22
Score: 100
Joined: 2/4/2004
Last Login: 5/24/2013
From: hayward, CA, USA
Status: offline 		Kommander, it can't be fixed.

Hide Signatures

(in reply to kommander)
       Post #: 21

RE: TT 40Pro endplay? - 4/29/2012 12:14 PM   
jaka


 

Posts: 7183
Score: 158
Joined: 12/11/2001
Last Login: 5/24/2013
From: Upplands Vasby, SWEDEN
Status: offline 		Hi!
????
Are you referring to my statement?

_____________________________

Jan Karlsson - Supplier MVVS Products

Hide Signatures

(in reply to kommander)
       Post #: 22

Page:   [1]
All Forums >> RC Airplanes >> Pylon Universe - RC Pylon Racing >> Q-500 Racing >> TT 40Pro endplay?
Page: [1]





Jump to:


 
Google 



Search | Marketplace | Event Calendar | Local Clubs | Magazine | Product Ratings | New Products | Discussion Forums

Photo Gallery | Instructor Search | Field|Track|Marina Search

Advertisers | Hobby Vendor Resources | Rate Manufacturers | Sign In/Sign Up

SITE MAP!   : :   FORUM RULES

RC Universe is a service of Internet Brands, Inc. Copyright © 2001-2013.

Charities we support that also need your help
Yorkie Rescue | Humane Society | ASPCA | Crohn's-Colitis America


1.281RCU1