Re: how "tight" should the crankshaft be with new bearings?

"TranSurgeon" wrote

good rule of thumb is you should be able to hook your little finger over one > of the counterweights and turn it easily, a really good one will go for a > half-turn or more with a flick of the pinky

Agreed. When I'm replacing pistons in 3100 engines, I can turn the crank by hand with the pistons and new rings in place, con rods torqued up, no heads on the engine, engine bolted to the torque convertor and trans.

Ian

Reply to
shiden_Kai
Loading thread data ...

somehow, I juest KNEW you'd appreciate that high-tech definition............

Reply to
TranSurgeon

If they did that:

They're asking for a crack to happen. Read the manual, for every crank, there is a specified fillet radius!

Refinish King

performance

Reply to
Refinish King

Agreed,

Sounds like he either:

1: Got a bent crank.

2: Got a crank cut 00.9

3: Even better, the machine operator was on crack and left the machine on a 1/2' stroke when doing the mains?

LOL

Refinish King

Reply to
Refinish King

We get cranks ground .010 under in order to get a bigger fillet radius all the time, for formula ford cranks. Very common. I have no idea what the new radius, I just ask John at Canada Chrome to do it and he does it. he's been grinding cranks probably longer than I've been alive.

Brian

Reply to
Brian

Reply to
mic canic

bull crap

youo can torque 'em as many times as you want, and it still won't make it too loose..........

yeah, those chain tensioners on small-block Chevies sure work good.............

Reply to
TranSurgeon

Reply to
Will Honea

Ditto! It's from 'not' using plastigauge to double check things.

And the one that the Jeep engine in question 'doesn't' have works really good too.

I wish this fool would go away with all his BS. He 'might' know something, but it certainly isn't Jeep engines and he keeps telling people to do things that will cost them big bucks or are just plain wrong.

A timing chain tensioner on a Jeep 4.0. LOL!

Mike

Reply to
Mike Romain

A radiused fillet is less likely to crack than a sharply ground one, re the stress raiser phenomenon we have discussed before.. I think that more often than not, the fillet is not intented to be left overly large...it is probably a result of less than precise machining.

It can interfere with the edge of the bearing, just as "c" said.

I never heard of anyone using narrower bearings, but they do 'relieve' the edge of the bearing where it might contact the fillet.

Seems I have seen a special tool to do this, but don't have one myself.

Reply to
HLS

It's called a bearing knife or bearing scraper:

But, if you have an excessively large fillet radius, especially in a cast iron crankshaft. that is the perfect place for a radial crack to begin.

The fillet radius should be ground with the stone dressed to the propper radius for the crankshaft in the machine.

Refinish King

Reply to
Refinish King

I guess Lunati and all of the other aftermarket crank manufacturers have been doing it wrong all these years.

formatting link
It is common knowledge that a radius reduces the chance for a stress crack by ditributing the stresses evenly across the radius. The bigger the radius, the more area to absorbs stresses.

Chris

Reply to
c

"The King" has never let facts get in his way. He just babbles on whether he knows what he's talking about or not. Bob

Reply to
Bob

That's on new:

not a regrind.

So like I said, go look in the book that crankshaft grinders use. You'll be surprised, and more surprised at what they use for gauges to check the stones when they dress them.

Refinish King

Reply to
Refinish King

Do you want me to use the book that I used for the 4 years that I worked in a racing engine shop, or do you have a specific one in mind?

Chris

in

Reply to
c

APRA Crankshaft specifications and tolerances!

Racing engine shops use different tollerances, I've been there!

Refinish King

formatting link
> >

Reply to
Refinish King

mr roman heres the parts number the tensoner you say doesn't EXIST!!! for the 4.0

33003440

Mike Roma> TranSurge> >

Reply to
mic canic

Yeah they do, but you are dead wrong as to why they do it. It has nothing to do with a small fillet increasing strength, it has to do with providing clearance for the sides of the bearings. It is common sense (maybe this is why you don't get it?) that a larger fillet increases strength. 'nuff said.

Chris

in

wrote

Reply to
c

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.