R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Nitro Off-Road

Reply
 
Thread Tools Search this Thread
Old 01-28-2009, 07:06 PM   #1
Tech Regular
 
iLL-Mitch's Avatar
 
Join Date: Jun 2008
Location: NOR~CAL
Posts: 326
Trader Rating: 10 (100%+)
Default OS rod maybe bad

I got an OS vspec... I was replacing the bearing and noticed slight play between the rod and crank... do i need to replace the rod or crank?...
__________________
MBX6B - Ninja JX - Proline Tires
SC10 - Tekin RS Pro - Tekin Redline 10.5 - Pro-Tek Lipo
B4 - Tekin RS Pro- Tekin Redline 13.5 - Pro-Tek Lipo
TC5R - SOLD
B44 - SOLD
iLL-Mitch is offline   Reply With Quote
Old 01-28-2009, 07:12 PM   #2
Tech Fanatic
 
jaylude22's Avatar
 
Join Date: Dec 2007
Location: Redding, Ca.
Posts: 814
Trader Rating: 93 (99%+)
Default

The only way to know which needs replacing is to measure the crank pin with digital calipers. Measuring it means you need to know what the original size was/is to know if it's within specifications. If I remember correctly, the original diameter is 5mm. Someone else may be able to chime in and specify how much smaller the pin can be without causing a problem. V-specs are somewhat notorious for this problem because unlike the Speed/JX-21(or just about any of the nova motors), they don't have the small hole on the front side of the rod to allow the oil to pass through to the crank pin. The lack of lubrication causes the components to wear much faster than they otherwise would.
jaylude22 is offline   Reply With Quote
Old 01-28-2009, 07:12 PM   #3
Tech Master
 
mugenb46's Avatar
 
Join Date: Jun 2006
Location: springfield tn
Posts: 1,385
Trader Rating: 4 (100%+)
Default

Quote:
Originally Posted by iLL-Mitch View Post
I got an OS vspec... I was replacing the bearing and noticed slight play between the rod and crank... do i need to replace the rod or crank?...

If you have around 2 or 3 gallons on it yes replace the rod, also inspect the crank pin, if it look's egg shaped it's almost going to decrese the life of a new rod. 2 or less gallons a new rod should do the trick.
__________________
Brian Carey
Pro Twister Mods
brian@protwistermods.com
615-838-5373
mugenb46 is offline   Reply With Quote
Old 01-28-2009, 07:15 PM   #4
Tech Regular
 
iLL-Mitch's Avatar
 
Join Date: Jun 2008
Location: NOR~CAL
Posts: 326
Trader Rating: 10 (100%+)
Default

i prolly ahve min of 4 gallons ill look at it and let you all know. Thanks
__________________
MBX6B - Ninja JX - Proline Tires
SC10 - Tekin RS Pro - Tekin Redline 10.5 - Pro-Tek Lipo
B4 - Tekin RS Pro- Tekin Redline 13.5 - Pro-Tek Lipo
TC5R - SOLD
B44 - SOLD
iLL-Mitch is offline   Reply With Quote
Old 01-28-2009, 07:59 PM   #5
Tech Adept
 
chunk t's Avatar
 
Join Date: Nov 2008
Location: Elgin, IL
Posts: 225
Default

Quote:
Originally Posted by mugenb46 View Post
If you have around 2 or 3 gallons on it yes replace the rod, also inspect the crank pin, if it look's egg shaped it's almost going to decrese the life of a new rod. 2 or less gallons a new rod should do the trick.
Mitch, I'm going to partially disagree with Brian. Definately check the crank pin's roundness. My rule of thumb can be applied to any displacement engine. If the differance in concentrisity of the pin is 10%(or greater) it's gone.

I don't replace rods based on "X" number of gallons through an engine. I measure head clearance and port timings. These change as the rod & pins wear. Once they fall out of the range I need to maintain my performance envelope, then I'll swap rods (yes there other factors that will make me change a rod but those are case by case). Also, once you swap rods the crank pin will wear quicker in the beginning because the rod & pins are not a matched set like the originals were.

So, I guess what I'm saying is don't change the rod unless you have a good reason. and I've never been able to call a few gallons a good reason.
__________________
chuck "chunk" thomas
.......
1:10, 2-wd Stadium Trucks
B-Mod Tunnels
.......
If ignorance is bliss... I must be in heaven!
chunk t is offline   Reply With Quote
Old 01-28-2009, 08:01 PM   #6
Tech Elite
 
jpalessi's Avatar
R/C Tech Elite Subscriber
 
Join Date: Feb 2008
Location: SoCal
Posts: 4,747
Trader Rating: 55 (100%+)
Send a message via AIM to jpalessi Send a message via Skype™ to jpalessi
Default

Quote:
Originally Posted by iLL-Mitch View Post
i prolly ahve min of 4 gallons ill look at it and let you all know. Thanks
It that point just RUN IT! it's not worth the money to start replacing parts..it'll run good for another gallon or two.. more likely then not, the crank pin is already out of round. If it was a speed, or a JX, i would say replace the rod, with the DLC coated crank those engines are worth rebuilding. How much play is there? 00.02 is normal.
__________________
Joe Alessi
www.Lucky7RC.com
jpalessi is offline   Reply With Quote
Old 01-28-2009, 08:05 PM   #7
Tech Addict
 
Join Date: Sep 2005
Location: Southern CA
Posts: 743
Default

Quote:
Originally Posted by jpalessi View Post
It that point just RUN IT! it's not worth the money to start replacing parts..it'll run good for another gallon or two.. more likely then not, the crank pin is already out of round. If it was a speed, or a JX, i would say replace the rod, with the DLC coated crank those engines are worth rebuilding. How much play is there? 00.02 is normal.
Run it...
CarCrazy is offline   Reply With Quote
Old 01-28-2009, 09:27 PM   #8
Tech Master
 
fast11970's Avatar
 
Join Date: Nov 2006
Location: Freeport Texas
Posts: 1,007
Trader Rating: 1 (100%+)
Default

I had a V spec that I was worried about...Had a Gallon thru it an got it hot...Took it all apart, I determined the Con Rod Was bad...Ordered a new one...Mistake, It had the same play, the same run out, as the one gallon con rod, This was about 6 gallons ago, I still do not trust the engine...But I seem to run it alot when my "Modded" mills have "Issues".. Same Con Rod, I gave the new one to a buddy his lookedmore worn than mine!

I would not worry about the play yet...If you are running, an It aint got no punch or you start to eat plugs...Then a V Spec needs some lovin...


IMO (In Monkey's Opinion!)
__________________
MBX6
http://www.racemugen.com
fast11970 is offline   Reply With Quote
Old 01-28-2009, 09:38 PM   #9
Tech Champion
 
JAMMINKRAZY's Avatar
 
Join Date: Jun 2007
Location: Pittsburgh PA
Posts: 6,575
Trader Rating: 17 (100%+)
Default

I have about 6 gallons on my stock v-spec without changing anything. If it has alot of play, measure the crank pin and check it for roundness. if it is within spec replace the rod and run it. If the crank is out of spec run it and enjoy it while it lasts. It isn't worth replacing the crankshaft(pretty much on any motor).
__________________
-Koby Kubrin-
Thanks to my Sponsors:
Serpent America | Team Novarossi | Desoto Racing | Race AKA | Ridgeway Bodies
JAMMINKRAZY is offline   Reply With Quote
Old 01-28-2009, 09:44 PM   #10
Tech Elite
 
pinky2252s's Avatar
 
Join Date: Nov 2007
Location: Broomfield, Colorado
Posts: 3,278
Trader Rating: 4 (100%+)
Send a message via AIM to pinky2252s Send a message via MSN to pinky2252s
Default

I had over 10 gallons on my TRX2.5.... hell it got slower but it still lasted

I never replaced a thing besides the clutch and a OWB or two
__________________
Procrastinators Unite!.....Tomorrow
Team Terribles
pinky2252s is offline   Reply With Quote
Old 01-29-2009, 05:24 PM   #11
Tech Fanatic
 
GH Racing's Avatar
 
Join Date: Jan 2008
Location: Vancouver, Canada
Posts: 795
Trader Rating: 3 (100%+)
Default

After 4 gallons, I would change the rod
__________________
GH Racing by Golden Horizons. Buy Direct At: WWW.GHHOBBY.COM
FOLLOW US ON TWITTER NOW: twitter.com/GH_Racing
High Quality Machined Aluminum Parts and Accessories. Vancouver, Canada.
GH Racing is offline   Reply With Quote
Old 01-29-2009, 06:56 PM   #12
Tech Master
 
Join Date: May 2005
Location: michigan
Posts: 1,678
Trader Rating: 14 (100%+)
Default

no one has posted this yet - if you replace the rod in a stock v spec, get the speed rod, that has the oil hole in it to prolong the life.

a few of the guys i race with replace the stock rod right after break in for a speed rod and when they rebuilt the engines, they put a speed crank in there to.
o.s. power is offline   Reply With Quote
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
Team Magic G4 Motorman Nitro On-Road 11759 12-09-2016 05:09 AM
Atria Car Park Speedway tIANcI Malaysian R/C Racers 26519 12-07-2013 06:04 PM
Hobby stores and Crazy storys..... stefanos Nitro On-Road 10 03-22-2007 06:37 PM
Bore vs Stroke vs Displacement rmdhawaii Onroad Nitro Engine Zone 163 11-07-2006 12:07 PM



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off



All times are GMT -7. It is currently 12:57 AM.


Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net