If you could - Plain bearing 1100 crank

[RPE Racing]

Hi,

Just wanted to know the racers opinions on the roller bearing crankshaft.

We have been contacted by road racers with various issues on their roller crank 1100, both welded and non welded.

I would like to know if you would have a plain bearing 1100 or 1150, if you could.

Please state your application (drag, road race...)


Many thanks.

 

[GregT]

I suspect that you'd have to change the cases as well to achieve enough bearing area and support. Not permitted in most Post classic roadrace rules.
I also suspect that it's a very limited market you're looking at. The roadrace guys who are having trouble are at HP levels - and budget levels - most will never reach.

Personally I've been involved with a GS1000 top end on a GSXR plain bearing lower. Built for a particular set of odd speedway rules. It worked and was worth doing - but if we'd had to source a scratch built crank it wouldn't have been done.

 

[RPE Racing]

Thanks.

Do you know if this issues are restricted to road racing or are drag racers facing the same limitations?

 

[rapidray]

The cost involved would not offset the worth. The roller bearing cranks are VERY strong, & put up with a LOT of abuse & keep going!! To change to a plain bearing crank will require much higher oil pressure & a different oil pump also.
Ray.

 

[Doug]

The roller crank seem to be working well. In NHRA (No Harley Rules Anticipated) drag racing there are still about 5 Suzuki engines in the fray.

Yes, less weight reduces the energy required to accelerate a rotating mass and two piece rods would reduce the number of pieces comprising the crank, but would still require two or three pieces to retain the inboard crank gear.

For a one piece crank, a split crank gear would have to be bolted in place. A split gear puts four gear teeth at the split line. This is not a sound design as those four teeth don't have the strength of the rest of the teeth. A gear failure that of a tooth breaking off could lodge between the crank and clutch gear resulting in a catastrophic failure.

What would the FABs (Features, Advantages, Benefits) be to support the crank redesign and cost?

The Harley's and S&S engine with the 1903 design of two rods on one crank pin has been acceptable for a hundred years For drag racing at 10,000 RPM besides being on a paint shaker, the centripetal force of the bearing rollers is leading to failures.

I heard S&S is working on a V-twin engine design that has each rod on a separate crank pin.

 

[RPE Racing]

The roller crank seem to be working well. In NHRA (No Harley Rules Anticipated) drag racing there are still about 5 Suzuki engines in the fray.

Yes, less weight reduces the energy required to accelerate a rotating mass and two piece rods would reduce the number of pieces comprising the crank, but would still require two or three pieces to retain the inboard crank gear.

For a one piece crank, a split crank gear would have to be bolted in place. A split gear puts four gear teeth at the split line. This is not a sound design as those four teeth don't have the strength of the rest of the teeth. A gear failure that of a tooth breaking off could lodge between the crank and clutch gear resulting in a catastrophic failure.

What would the FABs (Features, Advantages, Benefits) be to support the crank redesign and cost?

The Harley's and S&S engine with the 1903 design of two rods on one crank pin has been acceptable for a hundred years For drag racing at 10,000 RPM besides being on a paint shaker, the centripetal force of the bearing rollers is leading to failures.

I heard S&S is working on a V-twin engine design that has each rod on a separate crank pin.

Why couldn?t you machine a straight cut gear on the one piece crank?

Longevity and serviceability of bearings, lighter weight, bigger stroke (theoretical), avoid crank misalignment, avoid roller bearing issues

I can?t seem to find any stroker cranks for the GS. Why is that?

 

[rapidray]

I can get stroker cranks every day. Call Falicon or Vance & Hines Motorsports in Brownsburg, Indiana. I wouldn't use a Falicon crank if it was free though!!!!
Ray.

 

[Doug]

Howdy RPE Racing,

As I see it, incorporating the gear into the blank crank forging would would be difficult to machine as gear teeth are usually cut using a gear hobb which would not fit with the gear being part of the adjacent cheek plate/counterweight.

It may be possible to cut the gear and the counterweight, though now there would be several gear teeth in the counterweight that will be picking up oil and throwing it around inside the motor. The current design gear also picks up oil and throws it around but the clutch gear squeezes out most of what isn't distributed by the gear. Cutting teeth into the counterweight removes some of the material that is part of the balancing. That could be overcome easily enough.

It may be possible to cut the gear using a shaper type cutting action. I see this as requiring some complexity of tooling design and shaping the gear to be a much slower process thereby increasing the cost to produce.

The gear could also be formed using Sinker type EDM equipment but the cost and time is prohibitive.

The gear could be made larger in diameter the the rest of the crank to allow faster and more accurate gear cutting. However, now the cases change, the cylinder block gets taller and heavier to accommodate longer rods to clear the larger gear. Then the clutch gets proportionally smaller and not able to hold power.

Admittedly, I don't know how modern GSXR or other brands of cranks are made. I know a little about GS's and turbine helicopters and I'm still learning about money. Darn, that's been a tough one.