cmb front bearing

[avbrando]

i'm replacing bearings on a cmb .67 and it has an open front bearing. does anyone know why it is open? can i run a seal on the flywheel side?

 

[hydro]

i'm replacing bearings on a cmb .67 and it has an open front bearing. does anyone know why it is open? can i run a seal on the flywheel side?

Normally the open bearings are of the best quality and phenolic retainers with lowest drag. Although I am sure you can get high end bearings that have seals on them too. There really no big advantage to a sealed bearing in model engines except for if maybe you have a nitro car or plane in dirt/dusty environment the seal keep the crap out but that does not apply in a boat application, plus the seal introduces parasitic drag which steals horsepower. The engine gets it's seal from the very close fit between the crankshaft and the front housing, not the bearing. Hope I helped you somewhat.

John

 

[steve wood]

you may be able to get wib bearings with a seal. the cmb bearings don't have one. i prefer a seal also, as they seem to improve low end torque, especially on a 21. it is not a big deal on the larger engines.

 

[hydro]

you may be able to get wib bearings with a seal. the cmb bearings don't have one. i prefer a seal also, as they seem to improve low end torque, especially on a 21. it is not a big deal on the larger engines.

Yes that is true, a sealed bearing will help crankcase compression/low end torque if the fit between the crank and housing is less than wonderful from either loose machining tolerance or if you let the bearings go to long in that particular engine and the crank stuffed the housing up. But in a normal engine it is not necessary and it does introduce unwanted drag.

John

 

[steve wood]

you may be able to get wib bearings with a seal. the cmb bearings don't have one. i prefer a seal also, as they seem to improve low end torque, especially on a 21. it is not a big deal on the larger engines.

Yes that is true, a sealed bearing will help crankcase compression/low end torque if the fit between the crank and housing is less than wonderful from either loose machining tolerance or if you let the bearings go to long in that particular engine and the crank stuffed the housing up. But in a normal engine it is not necessary and it does introduce unwanted drag.

John

i will have to disagree with you on that. i don't run engines with loose tolerances or worn bearings or cranks, and i still feel that a rubber sealed bearing on the flywheel end of a 21 is the best way, if you can find one. some times nova's come with them from the factory, and sometimes they don't. same way for the cmb 21's. but it's hard to buy new ones, we have tried. i don't think the drag thing amounts to diddly squat.

these are all personal opinions, so don't any one get all wrapped around the axel about it!

 

[tnrcboatracer]

In some cases the sealed bearings have a wider race than the open bearings. This is especially true of the 607, 608, 609 sizes. Not sure about the 6000. the 6000 WIB's I got from Mike Cathey for my MAC 67/84 were shielded, but not sealed.

 

[avbrando]

thank's alot guys, i'm glad to have people like yourselves to help us new boaters

 

[Mike Cathey]

i'm replacing bearings on a cmb .67 and it has an open front bearing. does anyone know why it is open? can i run a seal on the flywheel side?

I have WIB bearings for the CMB 67 that have a shield on both the large and small bearing. I recomend to my customers that they remove the shield from the big bearing and keep the shild in the small bearing facing the flywheel. Keeps the water out of the motor a little better or any loose crud.

$40 a set plus $5 shipping for 2-3 Priority Mail in the U.S.