CMB 45 Rod Failure

[Terry Keeley]

Hell Jay if that's the first piston you've holed you haven't been runnin' them hard enough

 

[david cox]

To ALL:
Customer service was great with Tidewater Engineering and Machine Company. They are replacing my motor free of charge and they sent it next day service.

Hi GMC7:

Did Tidewater give any explanation about the rod failure? Do they think there is a bad batch of rods out there, or is this an isolated case?

-David

 

[GMCSW7]

Hi GMC7:

 

Did Tidewater give any explanation about the rod failure? Do they think there is a bad batch of rods out there, or is this an isolated case?

 

-David

David,

They did not give an explaination to the rod failures, I pretty sure that it just came to light with Tidewater and their currently working the issue.

There has been alot of speculation on RC boat sites about what could cause the failure of the rod.

Use the 2004 CMB this weekend for a race in Evansville and the motor was great. No problems encountered. Still breaking it in..

Giving them a call on Monday to tell them how the weekend went.

Only time will tell!

Steve

 

[TimD]

Wild Bill's didn't blow up this weekend either :lol:

 

[Ian Folkson]

I have today spoken to CMB and the problem appears to be that some of the main bearings are not strong enough

and are flexing due to the flexi shaft movement.

This allows the conrod to touch the case and causes it to break. Not all the motors have the same main bearing so only some have the problem. I do not at the moment know the name of which make of bearing has the fault. If someone with a broken motor can read the name and number of their bearing we all would have an idea what to look for.

Ian Folkson

iansboats.co.uk

 

[DaveMarles]

Ian, Surely thats the front bearing. The main bearing doesnt locate the crankshaft on a hydro motor.

 

[Wild Bill]

Hey Tim - Birthday Boy: you are right, my new CMB Cam 45 was 'honking' on Sunday, wasn't it?

I have to thank Tony Grinter of Hobby Supplies, the Australian agent for CMB. He contacted me after my post and we went through the problem. I sent him all my 'bits' from both broken engines for him to examine. Tony sent me back (and free of charge, I might add) a new case, new crank (with the large pin), new rod and needle rollers. I re-built the engine with new, original INA bearings and we ran it. When we stripped it down, after running a gal of fuel, it was evident that the rod had been rubbing in the case, just like the others that had broken. I also noticed that some others had reported this complaint on the thread.

Again, I sent back all the bits to Tony for inspection. He checked it over and then came up with an idea. He re-built the engine again with another new crank, new needle rollers and new WIB Swiss bearings. We ran the a--- out of it last Sunday, went through another gal of fuel. Pulled it down and not a mark anywhere. In conversation with Tony, he had mentioned that he orders all his engines with these WIB bearings fitted as standard as he feel they are the best available.

I have to be honest and say that I did not think that changing the bearings would have provided such a simple fix to such a dramatic problem. It would appear that the continual 'banging' of the rod on the case was enough to cause these massive failures we have seen. It also explains why it does not happen to every engine as it depends on the individual bearing quality. Tony has kept CMB in the loop with all this since the start. They even had 20 rods checked for hardness and all were found to be within 5% of spec.

Tony berated me for not contacting him straight away. I explained that we did not get these engines from him but from the states. He brushed this aside and said "let's fix the problem and worry about that later". Hobby Supplies have now replaced, free of charge, all the parts required to rebuilt the engines that were a problem here in Oz. I can't thank him and CMB enough for their assistance and commitment. My post was not about getting anything 'free', it was an honest attempt to find a resolution to this unique, intermittant problem. Thanks to Tony's involvement, I believe we now have an answer and a quick, inexpensive remedy.

Bill Annabel

 

[aaron alberico]

sounds good Billy as i'm going to Tony's[ Hobby supplies ]today to buy a new cam45. what i've heard they go like a rocket...... what pipe r peoplr running on them in a outrigger at what length

 

[Wild Bill]

Hi mate.

Running a Mac 45 Nitro pipe at 10 and 1/4" with exhaust throttle. Those things do rev even with cupped H22.

Bill.

 

[Terry Keeley]

Great, it looks like you have the problem solved. BTW, what brand were the bearings that caused the problems???

 

[WIDEBOY]

I must also thank Tony Grinter from HOBBY SUPPLIES as he has replaced my engine that blew up the next day after WILD BILL as my one was purchased from the same place as Bills now WIDEBOY BOATS can go to the USA with good engines thanks to TONY WHO WOULD HAVE THOUGHT IT WAS THE BEARINGS