thoughts on straight-cut gears (noise)

hlwimmer · Post by **hlwimmer** » Fri Nov 21, 2003 11:40 am

there are a few old posts that i've read through...

any other thoughts on the noise of straight-cut gears? after several helical cam-gear failures, my mechanic is suggesting steel/steel straight-cut cam/crank gears...

i'm trting to build a sleeper, old school 1776 motor (dual zenith, abarth muffler) for my 63ragtop... will the straight-cut noise drive me (more) crazy?

Post by **Marc** » Fri Nov 21, 2003 11:45 am

hlwimmer wrote:there are a few old posts that i've read through...
any other thoughts on the noise of straight-cut gears?...

I can't think of anything to add beyond what was in these two threads:
http://www.shoptalkforums.com/viewtopic.php?t=51248
http://www.shoptalkforums.com/viewtopic.php?t=50550

hlwimmer · Post by **hlwimmer** » Fri Nov 21, 2003 12:34 pm

thanks for the links marc... given that i would prefer helical gears (less noise), do you think its a good tradeoff (more noise = reliability or gear set vs. less noise = less reliable cam gear due to recent manufacturing flaws)...? i know is sort of a guessing game as to when/if the helical gear would fail...

Bruce2 · Post by **Bruce2** » Fri Nov 21, 2003 1:42 pm

What kind of valve train did you have that was taking out cam gears?

hlwimmer · Post by **hlwimmer** » Fri Nov 21, 2003 2:10 pm

i wish i could be specific, but i really don't know... it is/was a fairly standard 1776. the rebuild recept listed a bunch of scat products, but i don't have it in front of me right now... a very reputable and trustworthy builder in sanjose did the work. no yahoo driving and i was running dual kadrons and a 010 @ the time, along with a bypass oil filter. the engine started knocking like crazy after less than 1000 miles. on tearing the engine down, the culprit was IDed -- an excessively worn cam gear with a whole-lotta play. it was blamed on a manufacturing fault of the gear, thus the want to go to straight cut gears by the mechanic. i'd rather have quieter helical, but don't want this to happen again...

vwpride73 · Post by **vwpride73** » Fri Nov 21, 2003 2:45 pm

I personally like the straight cuts. They sound like a super charger whine. But not as loud.

Post by **Marc** » Fri Nov 21, 2003 2:55 pm

As Bruce2 was hinting at, it takes a pretty demanding valvetrain to cause that kind of damage - and my impression is that your engine probably doesn't contain anything very radical in that department - it certainly shouldn't need to - but without the details who knows?
Anyway, I'm kind of surprised that an experienced builder would give up on stock-style gears that quickly - they don't normally have any problems lasting for many miles, perhaps these all were defective but it seems unlikely. I'd suspect there may be a problem somewhere that hasn't been recognized yet, and "bulletproofing" with steel gears may just make the next-weakest link break.

vwpride73 · Post by **vwpride73** » Fri Nov 21, 2003 3:00 pm

As Marc stated the stock gears should have no problem lasting for a while. They've been like that since they started producing the Vw engine. And were disigned like that to reduce noise but can last for a long time. I would have to agree with Marc about the defective gears (just a guess).

Guest · Post by **Guest** » Fri Nov 21, 2003 6:54 pm

for what it's worth, ray shubert @ volksauthority built the motor... he's done an excellent job (at what he can control (i.e.: likely not his fault the gear failed)) and really cares about the project -- its not your typical build... lots of old-school and porsche accessories will make it a neat, noteworthy (but not too out of the ordinary) engine. this cam-gear failure has happened on a few other engines he's serviced recently, thus his gun-shy-ness of the newer cam gears

i have the receipt in front of me now... it lists:
69mm rebuilt crank
engle w-100 cam
scat lifters
heavy duty cam bearings
single HD springs
stock rods
90.5mm p/c 90.5X69

i know this isnt a very comprehensive list -- i'm not a complete gearhead (and could use some more experience/exposure). i'm feel fortunate to have found a builder who has a good reputation and who understands what (conceptually) i want and can translate that into mechanical realities. i'd recco volksauthority in a heartbeat.

anyway... from this and the posts that marc listed, it seems that the folks who like to be heard coming down the street like the whine of the single-cut gears... those who prefer a quieter ride don't prefer them... i think i'm going to take my chances with the new helical gear set that ray has found (he went through 19+ sets to find this one, but still has his doubts)... i have 2 choices (1) be very likely unhappy with my new motor due to noise or (2) be upset when/if the cam gear fails again... the odds of me not liking the straight-cut noise are like 1.5:1... the eventual failure of this particular gear set is probably more like 10:1... so the odds are in favor of the new helical gear set...

thanks everyone for the opinions, advice and links... more would certainly be appreciated, either in this thread or offline. all experiences are worthwhile experiences.

392HemiTCoupe · Post by **392HemiTCoupe** » Fri Nov 21, 2003 9:06 pm

-- ray shubert @ volksauthority built the motor... he's done an excellent job (at what he can control (i.e.: likely not his fault the gear failed)) and really cares about the project.

--this cam-gear failure has happened on a few other engines he's serviced recently, thus his gun-shy-ness of the newer cam gears

--i think i'm going to take my chances with the new helical gear set that ray has found (he went through 19+ sets to find this one, but still has his doubts)

--the engine started knocking like crazy after less than 1000 miles. on tearing the engine down, the culprit was IDed -- an excessively worn cam gear with a whole-lotta play. it was blamed on a manufacturing fault of the gear

--given that i would prefer helical gears (less noise), do you think its a good tradeoff (more noise = reliability or gear set vs. less noise = less reliable cam gear due to recent manufacturing flaws)...?

........Humm..What recent manufacturing flaws..??? What brand is he buying? You only get what you pay for.

--i have 2 choices (1) be very likely unhappy with my new motor due to noise or (2) be upset when/if the cam gear fails again

I think you have a 3rd choice......... A different mechanic, if he doesn't find the problem, Before he puts it back together, again.....I say it's not the cam gear it's self, that's the problem. (unless one of them was a used, worn out in first place)

MY two cents worth!

Pat

Trikes are for Kids!

Bruce2 · Post by **Bruce2** » Fri Nov 21, 2003 10:19 pm

If there's a rash of bad cam gears on the market right now, straight cuts will make the problem go away, but I have another solution. Get a stock original VW cam and grind off the rivets. Drill the holes bigger and have them spotfaced for bolts.
All I use is stock gears and they have held up to much higher stress than your engine. Its not helical gears that are the problem in your engine.

Max Welton · Post by **Max Welton** » Fri Nov 21, 2003 10:24 pm

392HemiTCoupe wrote:I think you have a 3rd choice......... A different mechanic, if he doesn't find the problem, Before he puts it back together, again.....I say it's not the cam gear it's self, that's the problem. (unless one of them was a used, worn out in first place)

MY two cents worth!

Pat

Trikes are for Kids!

And to yours I'll happily add my own .02.

If I know Ray Shubert (and I do), having multiple engines breaking gears has him pulling his hair out. Ray does this for a living and he is one of the good guys.

Yeah, switching engine builders is always an option. But this particular problem will turn out to be bad parts.

hlwimmer · Post by **hlwimmer** » Fri Nov 21, 2003 11:43 pm

its hard to find someone you trust -- and its hard to find someone who's good @ what they do... at volksauthority, i've found both. i believe ray when he tells me that the gears he's been getting aren't like they used to be... thus his suggestion to go with straight-cuts. as a good mechanic and good listener, he also knows that a noisy engine wouldn't be ideal for me... thus the question to the group as to the noise associated with s-c gears... like i said before, the odds are greater that i'll be unhappy with a s-c engine noise than another cam failure... but i also value the opinion of those who have had other experiences (thanks for sharing... really. it helped out a lot).

JohnK · Post by **JohnK** » Sat Nov 22, 2003 9:14 am

I think Bruce2 has a good solution. A little more work than just slapping a cam gear in, but will be right. I've talked to Bergs years ago about straight cut gears and they said they would not use them except on Chevy springs since they wear out faster than helical gears. I think your mechanic could find the right fit with some old stock cams, then take the gear off that fits right and modify it. Sounds like he is doing the best he can. If you've got a mechanic that is working to make it right instead of telling you it's your fault, I don't think you'll find somebody that will do much better.

vdubsinjensen · Post by **vdubsinjensen** » Sat Nov 22, 2003 2:26 pm

I've found that straight gears aren't always that noisy.The Berg steel/steel ones in my 2332 are very quiet.My buddy just built a 2007 and is useing gears from Empi.This motor has the loudest gears I've heard.I don't know that it has anything to do with the brand,or more so the case that's being used.I've used several set from Scat and haven't had any problems as of yet.Paul

Shoptalkforums.com

thoughts on straight-cut gears (noise)

thoughts on straight-cut gears (noise)

Re: thoughts on straight-cut gears (noise)