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Mon Dec 27, 2021 8:52 am

Yea that CB pros are crazy loud.. 2 different motors I built with them are just painfully loud. I will never use them on purpose again.. not my style..

Mon Dec 27, 2021 8:55 am

Another vote for CB's pro series for Champion Noisemaker. Just set up a set of them and was there for the break-in and with normal ~.003" backlash these things couldn't even be talked over.

Of course this means, without question, these could have a better tooth profile. Something about the cut is not quite right. It may be intentional and may not be terribly detrimental to gear life but GEEZ. Talk about noise.

Mon Dec 27, 2021 9:52 am

I agree 100%, the teeth have machine marks, almost serrated, which must contribute to the noise

On initial started up it scared the hell out of me. For future builds I will only use their standard set. It’s a shame because I like the crank gear with the spacer built into the gear

Can see here

Mon Dec 27, 2021 9:59 am

txoval wrote: I agree 100%, the teeth have machine marks, almost serrated, which must contribute to the noise

On initial started up it scared the hell out of me. For future builds I will only use their standard set. It’s a shame because I like the crank gear with the spacer built into the gear

Can see here

That is a very nice feature of the CB Pro's. No fiddling with that VW spacer.

Mon Dec 27, 2021 11:51 am

67rustavenger wrote: txoval wrote: I agree 100%, the teeth have machine marks, almost serrated, which must contribute to the noise

On initial started up it scared the hell out of me. For future builds I will only use their standard set. It’s a shame because I like the crank gear with the spacer built into the gear

That is a very nice feature of the CB Pro's. No fiddling with that VW spacer.

Doh! Very good point I forgot about that gear! I just don’t want such an extremely loud setup. Of course you never know for sure 100% what you’re going to get. I wonder if anybody has run a quiet set of these?? 🤔

Otherwise I’m inclined to get another set….and I’ve already got these. 🤦‍♂️ Wonder if I could mix up the crank gear with, say a Scat (or whoever) cam gear to enjoy the built-in spacer but lessen the noise with another’s cam gear? 🤷‍♂️

Fri Dec 31, 2021 8:53 pm

More thoughts.........

#1.) (for vwracerdave) ..... If it has to do with Cam/Crank centerline distance, then do you want less distance (tight lash) or more distance (more lash) for less noise?? (or vice versa)

#2.) Wonder if/what a process like "REM" polishing might do to potentially loud gears

#3.) Anybody ever had a "loud" set of magnums???

#4.) If I skip all together, anybody got an opinion on Scat's multi-tooth HELICAL CAM GEAR?? -----> https://scatvw.com/product/adjustable-type-bolt-on-aluminum-cam-gear/

TIA

Fri Dec 31, 2021 11:57 pm

tighter backlash equals louder…

I have heard from some that said the Pro Series were quiet, but I think they must have been an older set.

Sat Jan 01, 2022 1:05 am

I have had the same magnum gears in 3 different cases and always been quiet.

Sat Jan 01, 2022 8:12 am

I have run the “standard” CB straight cuts in 3 engines and they were quiet.

Can you still buy the Magnum gears?

Sat Jan 01, 2022 9:23 am

txoval wrote: I have run the “standard” CB straight cuts in 3 engines and they were quiet.

Can you still buy the Magnum gears?

Yes, in fact, I think I can still get my hands on the magnums!

Sat Jan 01, 2022 10:31 am

I also saw that Engle makes a pretty badass set of adjustable gears. I may have to buy a set

Sun Jan 02, 2022 1:14 pm

The CB Pro's are noticeable but not at all loud in my 40hp.

Sun Jan 02, 2022 2:21 pm

That's about perfect! And you said those are the "pro" (1400) series set?

If I knew for sure I'd have that I'd be all in!

Any chance you remember what kind of lash those had??

If it's truly about cam/crank centerline then why did I see 2 sets (1 CB regular 1399's and 1 CB Pro 1400's) go together identically lash-wise and yet night & day noise difference?

Is there more to it than Cam/Crank centerline/concentricity?
Material?
Surface finish? (thus my REM polishing inquiry)

I wish things were etched in stone a little more on the matter.

Sun Jan 02, 2022 3:04 pm

Lash is just part of the equation.

Teeth profile, metal finish, etc

I honestly believe the teeth profile is why my CB Pro Series are so loud. Same case, same crank with CB standard straight cuts was quiet. But those gears are smooth as butter.

Sun Jan 02, 2022 3:53 pm

txoval wrote: I have run the “standard” CB straight cuts in 3 engines and they were quiet.

Can you still buy the Magnum gears? Ron Lummus carries Magnum gears.

https://ronlummusracing.com/product/cam-gears/

Sun Jan 02, 2022 7:19 pm

I built my motor with straight-cuts because i like the noise,
And also i got the set of gears for almost free.

These being the cheapie cast Dyna-gear set,
They had some lash - more than i liked.
Since i like to try things i ran them anyways.

They don’t have much whine really,
They’re more like clackers.

Maybe circumstantial evidence that tighter lash makes more whine?
:-k

Mon Jan 03, 2022 1:20 pm

I have those Ron Lummus sourced Magnum straight-cuts in my basement now and they weren't particularly loud even when they were running with a cam that lifted .420" at the cam and crower dual springs. They had .004" lash when I blueprinted the engine teardown for detective reasons. (The top end got sanded bad in the Baja 1000 and had a host of other issues.) I would say the CB pro series gears we just set up in Kangaboy's new 78.4x92 are about 3 times louder. I have never heard CBs "regular" allegedly quiet straight-cuts.

Mon Jan 03, 2022 1:52 pm

Jimmy,

Thank you very much for the feedback! That sounds about right!

Mon Jan 03, 2022 2:21 pm

RandyV wrote: That's about perfect! And you said those are the "pro" (1400) series set?

If I knew for sure I'd have that I'd be all in!

Any chance you remember what kind of lash those had??

Yes, definitely the PN-1400 Pro version. If I measured lash I probably didn't write it down anywhere, and if did I don't remember where I wrote it down. :lol:

This was some of the extra parts I had laying around when I built the 40, I had them so I used them.

Mon Jan 03, 2022 2:52 pm

Nice pile! Kinda crazy to think of 40hp with straight cuts but cool! Heck, everybody chases down those 36hp less-helical gears so why not, eh?

Same exact package as I have on the CB 1400’s. 👌. Have another motor (turbo) going together soon with the 1400’s . Will be interesting to see how loud they come out.