CMB 45 Rod Failure

[Don Ferrette]

Do mac motors have the same problem they are made in the same factory ????if it is a design problem why has mac not got the same problem

Made in the same factory, virtually the same rod by design. I've run the crap out of my MAC45 & all my MAC motors for that matter. But then again, Andy is known for keeping a close eye on the motors that come to him. There was a problem with the machining of the rod clearance slot on the bottom of the CMB45 case that when the crank thrust forward the rod would rub the case. Wonder if this is still the problem?? The stock rod is strong & to have them just break is very unusual. One of the posted pics almost looked like there was a tearing action on the rod which to me would further support the case binding theory. :blink:

 

[AndyBrown]

Of all the MACs with steel Rods ( 45, 67, 84 ) we have had two Bend due to hydrolic compression,

and One break at the top after a full season of racing.

One of the bent rods was from a MAC 84 and was compressed into a complete "Z" bend, so these steel rods are not normally brittle.

 

[Anders_Martinelle]

There was a problem with the machining of the rod clearance slot on the bottom of the CMB45 case that when the crank thrust forward the rod would rub the case.

I had that in all of my MAC 84 engines (3 of them) so it`s not just a 45 engine problem.

Anders

 

[craig]

Don

Thanks for that after you suggested that i had a close look the small end is of the rod is polished on the face facing forward as like a thrust bearing.

Also the big end is polished on the ssurface facing the drum valve, the drum valve has rupping marks on it as well from conrod and needle roller bearings my engine had two gaskets on the backing plate i wonder how many gaskets are on the others.Do not get me wrong i would love to keep running these engines as long as this problem can be fixed and admitted to that there is a problem.

 

[TimD]

No, but you can have the bits and 'go for it'. I would just like to know why and see if it can be fixed - long term.
Thanks mate.

Bill

That motor must owe you a small fortune. I don't want to get into the same situation so I'll pass! Just out of curiousity - is the rod the same dimensions as the MAC rod?

Tim.

 

[Wild Bill]

Pass! :huh:

I'am an old man Tim, I don't know all that stuff.

Sure you don't want to have a look? h34r:

 

[TimD]

Pass! :huh:
I'am an old man Tim, I don't know all that stuff.

Sure you don't want to have a look? h34r:

A very fast old man I might add Bill - don't sell yourself short. Did you see the twin thread?

Hey - I heard your 67 engine was fast last weekend - must be that special pipe

before I start playing with 45's - Got to sell the wompy! I have another 45 hand grenade coming for inspection shortly.

 

[Wild Bill]

Yeh!

The 67 was the only thing that didn't disappoint. Went like a 'shot dog'. CMB 67 - out of the box - and I didn't manage to break it. Bloody thing goes great with that old Muck Pipe I had left over from my old scale.

Did you know that WIDEBOY BOATS now has a 67 hull? Took the first 45 out after it broke, took the second 45 out after it broke and then fitted the 67 in the same boat. Went great and didn't have to change a thing. It was an experiment to see if I could run the same boat in both classes on our forthcoming trip, you know, the trip you hate me talking about. <_<

Sorry, didn't you know that I blew TWO 45's last weekend? Yep, went through all the 45's I had. Talk about an investment. Can't wait to start adding up the parts.

So which brand of 45 are you putting your hard earned into? Just wisper so no-one else will know.

See ya.

 

[TimD]

Same brand as my 67 engine

The wideboy boat would absolutely haul with that motor and pipe in it! Did it hop or do anything silly?

Hint for you - try that Pipe @ 10 3/4", prop to suit and hold on!

 

[Wild Bill]

No mate. The beautiful, new, WIDEBOY 'KOOKABURRA' prototype just sat nice and hauled you know what.

You are a brave man, my pipe is 11 3/4" so I must have plenty to play with. I didn't want to shorten it too much, could afford to blow another new motor while 'running in' at my ususal WFO, sorry, full throttle. Must admit, it pulled any prop I put on it but stayed with a little one so as not to stress it too much first time out.

What prop do you run? Is it freely available or one of those 'custom' jobs?

WIDEBOY BOATS - Where winning becomes a way of life.

 

[Wild Bill]

Sorry Tim, I forgot to ask, what is that 45 engine again - abcdefghij[SIZE=21pt]K[/SIZE]lmn etc. Would that be right?

 

[TimD]

That would be right Bill.

Prop depends on the water. In Adelaide it was a stock H32. Regatta Centre I've been known to run a 1667 cut to 62mm or a H32 cupped up a lot! They are 1/4" props - for 3/16" use the props I mentioned earlier. They are close.

My engine didn't really go hard until the pipe was shorter than 11" B)

 

[Ian Inverarity]

Bill,

TWO motors in one day! :blink: That is having a bad day!! :huh:

I thought I had a bad 12 months last year doing 3 motors... <_<

Tim,

That 1667 is one nice prop!

Nitrocrazed racing: real subtle.

 

[AndyBrown]

There was a problem with the machining of the rod clearance slot on the bottom of the CMB45 case that when the crank thrust forward the rod would rub the case.

I had that in all of my MAC 84 engines (3 of them) so it`s not just a 45 engine problem.

Anders

The eariler MAC 84's had too little clearence between the bottom of the rod and the case. This caused the rod to rub the bottom of the case, but this never caused broken rods.

 

[AndyBrown]

No, but you can have the bits and 'go for it'. I would just like to know why and see if it can be fixed - long term.
Thanks mate.

Bill

That motor must owe you a small fortune. I don't want to get into the same situation so I'll pass! Just out of curiousity - is the rod the same dimensions as the MAC rod?

Tim.

Tim,

The MAC 45 rod is 3 mm (.118") longer than the CMB 45 rod.

Andy

 

[bsmtboy2]

I just received a e-mail for Ian Folkson in Europe, and he is going to meet with Mauro next weekend and let them know about this problem. Ian also says the EVO 45's are having a similar problem over there so we will be getting to the bottom of this soon

 

[Wild Bill]

Thanks for that Charles. It will be great to find out why and, even better, find out how to fix the problem.

I hope Ian posts the details of his conversation with the factroy.

Bill Annabel.

 

[aaron alberico]

hey boys its Aaron here im back.

i no what 45 engine i will be buying next couple of weeks, not gonna be a c.m.b. bought a 45evo/2 about year ago after three outings had to rebuild the engine, cracked crank new bearings, back plate etc, cost me bout $300 only ran twice since.

 

[DaveMarles]

CMB seems to be getting a knocking here and I wonder if its fair. CMB stands completely behind their products, they always have and I'm sure they always will. CMB sells only through distributors and they should be dealing with any problems and passing relevant info back to CMB. If the distributor doesn't want to help then buy from someone else next time. Believe me, if there is a genuine problem with a particular part in engine, CMB will fall over themselves to find a cure, but, and its a big but, it has to be a genuine material or design problem. The problem with the rods breaking on those hydro 45s could be that kind of problem but if the distributor involved doesnt want to do anything about it then maybe CMB doesnt even know. That particular engine is hardly sold at all in Europe and so the problem would not be apparent here. All racing engines are going to have problems now and again and CMB would not be the only company to have had particular problems now and again. I'm sure there have been plenty of horror stories about MAC engines and Picco engines in the past. Andy Brown takes care of any problems as he should but I'm not so sure about Picco.

As far as the posting here that there is problem with 45 conrods breaking on the EVOs used in Europe that is not true. The conrod breaking is a problem associated with a particular batch of 45 hydro engines as far as I can see. I'm sure someone will put up their hand and tell me that they know of an evo 45 with a broken conrod but thats life. I'm in the thick of the racing here and I know of none at all.

Hope this doesn't seem like a lecture, just trying to put things into perspective.

Dave

 

[AndyBrown]

It is true that CMB will go out of their way to correct problems when they learn about them.

As many of you know, it is my policy to take care of the customer first by replacing broken Engines/parts anytime I have the smallest suspicion that the problem is Material/manufacturing related. I just don't assume it's the boaters fault.

I then address the problem with the factory and they do what they can to fix it.

Sometimes the problems comes from an outside source, such as Heat treating and some of those companies are not so quick to admit fault. In those rare cases I have taken the responsabilty to replace parts upon myself no matter the cost.

I do this because I view the MAC engine as MINE and not just someone else's product that I'm selling.

Luckily in all of the MAC engines put into service we have had only one broken rod.

It was a MAC 45 that had been run for a full season and the rod had broke across the wrist pin hole.