Topic: Yoshimura CR Trans ?

[cavebear]

I have what is supposed to be a Yoshimura close ratio trans .There are no identifying marks but one of the gear clusters is clearly machined differently. Old timers tell me what you think.

CB 750 F2           Cb 750 F2        RATIO   Yoshimura?         RATIO
Countershaft        mainshaft                    Mainshaft
Tooth Count         Tooth count                 Tooth count
                                            
c1-47 teeth          1-18 t            1-2.60      1-25t             1-1.88
c2-41 t                2-24 t            2-1.70      2-28t             2-1.46
c3-36 t                3-27 t            3-1.30      3-29t             3-1.24
c4-34 t                4-31 t            4-1.10      4-30t             4-1.13
c5-31t                 5-33 t            5-0.94      5-35t             5-0.89

Thanks for your input.
                                Cavebear

[fastbroshi]

On a relative note, in case you haven't seen it.  This site can help you pick and choose your ratios or just figure out what you've got.

http://www.gearingcommander.com/

[bwaller]

It's easier to get a CR box now than forty years ago, so it may depend if you know how old the engine it came from is whether or not it's Yosh. I have an old Yoshimura catalog but it doesn't mention ratios. Nova gearbox ratios are different than yours. Who else offered one in the day, factory race kit? Quaife??

Some of the boys will know. How about a picture or two. 

[cavebear]

I'm going to count the teeth again to make sure I didn't make a stupid mistake.I am having trouble getting the second gear retainer clip off the main shaft, but i'll take what photos I can.

[Bill/BentON Racing]

I have a Yosh CR box,but have to go to MBSC now(brother losing his battle w/cancer)when I get back can take pics and check gear ratios for you.I thought 1sr gear CR was = to stock 2nd gear ratio? Good luck,Bill

[cavebear]

Thank you bill. Family first, toys second.   

[City Boy]

Hi.If your 1st gear on mainshaft is not integral with shaft,your trans is a genuine "970" unit.This is assuming,and I defer to others for this,that aftermarket close ratio units were not also like this.    Rock On

[kos]

First gear on mainshaft is a one piece deal on CR750 kit box. I had three of them in last 30 years!


KOS

[cavebear]

I had a chance to recheck the tooth count on the mainshaft gears and here are the corrected numbers


CB 750 F2           Cb 750 F2        RATIO   Yoshimura?         RATIO
Countershaft        mainshaft                    Mainshaft
Tooth Count         Tooth count                 Tooth count
                                           
c1-47 teeth          1-18 t            1-2.60      1-24t             1-1.958
c2-41 t                2-24 t            2-1.70      2-27t             2-1.518
c3-36 t                3-27 t            3-1.30      3-30t             3-1.20
c4-34 t                4-31 t            4-1.10      4-30t             4-1.133
c5-31 t                5-33 t            5-0.94      5-34t             5-0.911

Bellcow, as you can see my first gear is the same as the stock second gear as you suggested.

city boy and kos,the 24 tooth first gear IS integral with the mainshaft.




Each side of second/third gear showing tool marks the other gears don't.

[kos]

Thank you..I knew that... as I posted that comment.

KOS

[Bill/BentON Racing]

I had a chance to recheck the tooth count on the mainshaft gears and here are the corrected numbers


CB 750 F2           Cb 750 F2        RATIO   Yoshimura?         RATIO
Countershaft        mainshaft                    Mainshaft
Tooth Count         Tooth count                 Tooth count
                                           
c1-47 teeth          1-18 t            1-2.60      1-24t             1-1.958
c2-41 t                2-24 t            2-1.70      2-27t             2-1.518
c3-36 t                3-27 t            3-1.30      3-30t             3-1.20
c4-34 t                4-31 t            4-1.10      4-30t             4-1.133
c5-31 t                5-33 t            5-0.94      5-34t             5-0.911

Bellcow, as you can see my first gear is the same as the stock second gear as you suggested.

city boy and kos,the 24 tooth first gear IS integral with the mainshaft.




Each side of second/third gear showing tool marks the other gears don't.

Good job Cavebear. I need to find mine and I'll check and get back.Thanks,Bill

[cavebear]

SO, does anybody have or had a transmission with the same gear ratios as mine? Possibly a builders name? Thanks