[Mastiff-man]

I'm sure someone will say it's not needed, but has anyone had the rod journals on the crank groved to improve oil flow????

 

[GrandPaulZ]

Not me. That just reduces the effective bearing surface by that amount.

If it ain't broke, you'll be "fixing it" till you are.

 

[Mastiff-man]

GEE!!!!! GPZ, i wonder why they make performace bearings[ not for Triumphs] to do the same thing!!! You would think they would want to do as you said if TRUE!! BTW, the bearing rides on a film of oil, not METAL!!

 

[stewdog68]

grove the crank is a big no no!!

use grooved bearing but never grove crank. I don't think or know any machine shop that will grove the crank journals, if so you might as well throw it in trash.

grooved crank is a quick way to destroy expensive parts!!!


tell you what go ahead and do this and you will learn a hard lesson in life!!!

 

[stewdog68]

bearings do ride on oil from crank oil holes but, extreme care must be taken if enlarging them to much, crank losses strength and breaks

 

[Mastiff-man]

Stewdog, In the old days we used to grove the crank, before they started making bearings to do the same thing...

Because of the sludge trap, i wasn't sure it would work...

I've tried to find bearings that are groved, but unable to locate any.
Wouldn't know where i can find some do you???

Cheers, Don

 

[stewdog68]

i will assume bearing for your triumph

try Clevite or any other major bearing maker. but not sure if they even make these for triumphs.

 

[Mastiff-man]

Clevite is not making bearings for Triumphs .. SMR Engineering has Clevites bearings in 20 & 30 under, but that;s all i could find....

I used to use Clevite 77's in my GTO's.....Quality bearings!!!!

A grove that is 20thousands deep should not weaking the crank if you could turn one down that much, don't you think???

 

[GrandPaulZ]

I know the oil cushion is the effective instant supporting structure, but you are STILL reducing the "bearing" surface, and the instant molecular strengh of the larger oil volume is not as great as the thinner layer.

 

[Mastiff-man]

GPZ WRONG!!!!!!!!!The only way to reduce the bearing surface would be to use a bearing that is not as wide, which wouldn't make sense......I believe a company like Clevite, and their Engineers wouldn't manufacture a bearing to DAMAGE A HIGH PERFORMANCE ENGINE...btw,Groved bearings have been around since the mid 60's, and still availabe for performance engines....Could they be wrong all these yrs.??
I THINK NOT!!.

 

[GrandPaulZ]

Hey, that's my opinion, and I'm sticking to it.

I think Bonnies are perfect just the way they left the factory.

 

[Mastiff-man]

Hey, that's my opinion, and I'm sticking to it.

I think Bonnies are perfect just the way they left the factory.

GPZ, You have me all wrong!! I didn't say you couldn't SPECULATE!!

 

[GrandPaulZ]

Mastiff, you have ME all wrong!

I didn't say I was CORRECT!!!!!

 

[Mastiff-man]

Grand, Point taken!! But i was looking for FACTUAL information from someone that had tried, or knew of it being done before.....

Besides balancing, it's probably the best way to extend the life of the bearings.....That said, there's several performance ideas- technics that will extend the life of any stock engine....TRIUMPHS INCLUDED!!

Cheers, Don

 

[panda]

I am with GP on this. To groove the crank is very foolish. All you need do is mount a rod in a lathe with bearing installed ( you will have to bodge some kind of jig to hold the bearing true) Then use a boring bar mounted in the toolpost. I have done hundreds of bearings this way. The cutting edge needs to be D shaped to make a scooped groove without deforming the edges. Usually I put a circular groove at each side ( not too close to outer edge) then run a spiral from the middle out to each outer groove.

However with modern multigrade dino amd synthetic oils it is not necessary as they are thinner when cold and flow faster than the monograde oils for which the bike was designed.

 

[Mastiff-man]

I know the oil cushion is the effective instant supporting structure, but you are STILL reducing the "bearing" surface, and the instant molecular strengh of the larger oil volume is not as great as the thinner layer.

Panda this is what he said!!! Which goes aganist what you just said, so i'm not sure what your agreeing with, but that's OK since we all have opinions!! Crank or bearings, the end result is the same as far as preformance when placed under stress, an if not stressed, than certainly longer bearing life= longer engine life or why else would you do 100's of bearings as you stated??

Cheers, Don

 

[panda]

Panda this is what he said!!! Which goes aganist what you just said, so i'm not sure what your agreeing with, but that's OK since we all have opinions!! Crank or bearings, the end result is the same as far as preformance when placed under stress, an if not stressed, than certainly longer bearing life= longer engine life or why else would you do 100's of bearings as you stated??

Cheers, Don

The bearings I have done were mostly in large electric motors (usually mineshaft winding engines around 200HP) the bearings used are large and it helps to distribute oil. I would be very wary of doing this to a conrod bearing because they are relatively tiny, so the amount of surface removed is not trivial. The grooves represent mobile oil and not a pressure surface. I would absolutely not do it to the crankshaft, as if you trash shells they are easy to replace, cranks are another matter.

Some shells come with this channeling already done, some just have a central groove. Usually careful positioning of the oil feed hole in the crank by the manufacturer to coincide with max load optimises the feed to protect con rod bearings.

 

[sgh1962]

Hi Don, what you are describing has actually been performed on a number of older british machines.
It has also been applied to swing arm bobbins as a way of drawing more lubricant in to the bearing albeit normally with grease. they would scroll the bobbin (imagine a really coarse thread!!).
With regards to the crank the groove would run across the journal to a depth of approx 0.020" but not extend beyond the width of the rod. This would effectively create a wiper full of oil constantly being applied to the shell. Naturally the original oil hole would exit into this groove.
Steve

 

[GrandPaulZ]

Panda wrote: "I would be very wary of doing this to a conrod bearing because they are relatively tiny, so the amount of surface removed is not trivial. The grooves represent mobile oil and not a pressure surface"

I agree completely.