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RB26 engine Bearings Help...

adelzx9r

By adelzx9r,
in Engines & Forced Induction

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adelzx9r Apprentice

adelzx9r

Posted
Posted

Dear All,,

I would like your help in finding the correct Bearings for my engine, I had to take my crank to the machine shop and they said they must grind the crank which means I need to put in bigger Size Bearings. I was using NISMO Bearing and it was STD0 RRR40 but the workshop here don’t work with these numbers, so I need your help in :

1. Is it advisable to use the crank after all?

2. How will I know the correct size to use?

The work shop had measured the crank in came up with these figures :

Main Bearing size in STD is 54.98 and they have to grind the crank up to 54.48

Con Rod bearing size in STD is 47.98 and they have to grind the crank up to 47.73

Please help in finding the correct NISMO Bearings

Best Regards

Adel

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proengines Rising Star

proengines

Posted
Posted

Adel,

Going off the sizes that you have given it's more than likely that the crank has a bend in it. usually, if the crank needs to go .5mm undersize on the main journals it's because when it is set up in the machine running true on #1 and #7 main, #4 is running too far out to clean up at the first undersize. This happens quite often when a conrod bearing spins and the conrod journal gets very hot. It also means that you will end up with some conrod throws having extra stroke, if the mains have to go .5mm undersize, the extra stroke on a few cylinders could be up to almost .5mm which is bad for your engine.

Ask the machine shop if it is bent, or if the crank is already ground, ask them to check the stroke on each conrod throw. If either the crank is bent or the strokes are different on each conrod journal after grinding, throw the crank away and get another, it will save you troubles in the future and make a much nicer engine. you will be able to see if the crank had the bend ground out of it when you assemble it as the pistons will protrude more in the centre cylinders.

The other problem with going that far undersize is that you will be coming pretty close to grinding through the case hardening on the journals or even worse, on part of the journals.

WetGTR Proficient

WetGTR

Posted
Posted

Buying a new crank is the safest and I believe the best solution if you want your engine to last.

Not sure how much extra on top of machining a new crank would cost, but I think its worth it, or you might be back where you started.....another rebuild- its happened to so many of us

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