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Vevy
Samba Member
Joined: January 03, 2022
Posts: 7
Location: AB
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 Posted: Fri Nov 14, 2025 2:57 pm Post subject: Broken cam gear?! |
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Engine:
-1800cc
-88mm bore, 74mm stroke, counter balanced chromoly crank
-40/35mm heads with dual valves and 1.25 ratio rockers
-straight cut cam gears
-approx 10,00kms on rebuild
Driving home a couple weeks ago, engine died. No warning noises, just dead. Turned over fine, with no noises. Finally got to taking it apart and found the cam gear had exploded. Luckily nothing else was damaged except for the gear on the crank. What could possibly cause this? There is zero evidence of anything else wrong in the engine?
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Glenn 
Mr. 010
Joined: December 25, 2001
Posts: 80372
Location: Sneaking up behind you
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| Posted: Fri Nov 14, 2025 2:58 pm Post subject: Re: Broken cam gear?! |
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No lash, the gears might of fit together too tightly.
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Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"
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Vevy
Samba Member
Joined: January 03, 2022
Posts: 7
Location: AB
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| Posted: Fri Nov 14, 2025 3:00 pm Post subject: Re: Broken cam gear?! |
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Vevy
Samba Member
Joined: January 03, 2022
Posts: 7
Location: AB
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| Posted: Fri Nov 14, 2025 3:01 pm Post subject: Re: Broken cam gear?! |
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| Yeah thats the only thing I can think of, or defective gear. I wish they would add a bit more meat to them |
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Glenn
Mr. 010
Joined: December 25, 2001
Posts: 80372
Location: Sneaking up behind you
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| Posted: Fri Nov 14, 2025 3:03 pm Post subject: Re: Broken cam gear?! |
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The CB gear is beefier.
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Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"
Member #1009
#BlueSquare
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Rob Combs
Samba Member
Joined: December 30, 2020
Posts: 829
Location: South Bay LA, California
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| Posted: Fri Nov 14, 2025 3:35 pm Post subject: Re: Broken cam gear?! |
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| Glenn wrote: |
The CB gear is beefier.
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Is that the CB 1399 set? |
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Rob Combs
Samba Member
Joined: December 30, 2020
Posts: 829
Location: South Bay LA, California
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| Posted: Fri Nov 14, 2025 3:41 pm Post subject: Re: Broken cam gear?! |
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| Vevy wrote: |
| Yeah thats the only thing I can think of, or defective gear. I wish they would add a bit more meat to them |
I feel your pain. Just lost one myself, although mine was a helical aluminum gear. We have not gotten to the bottom of why yet. Mine will technically still start and run, but if I run it, it will eventually fail completely.
Did you have any backlash betwen the gears, as Glenn mentioned?
Did you happen to check whether the crank gear was completely round after it was installed? Meaning, was it too tight on the woodruff key, which could force it out of round, and cause a tight spot when running? Or, not as likely, could the #3/#4 main bearing area of the crank have excessive runout off the centerline? (bad grind, bent crank, etc...)
Too late to test the cam gear but is there anything left of the crank gear where it could be tested with a dial indicator? |
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Glenn
Mr. 010
Joined: December 25, 2001
Posts: 80372
Location: Sneaking up behind you
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Rob Combs
Samba Member
Joined: December 30, 2020
Posts: 829
Location: South Bay LA, California
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| Posted: Fri Nov 14, 2025 3:57 pm Post subject: Re: Broken cam gear?! |
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Once bitten twice shy. I'll be running those from here on out. Both engines will get `em.
OP, I hope you can nail down what caused yours to fail. Best of luck! |
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esde
Samba Member
Joined: October 20, 2007
Posts: 6392
Location: central rust belt
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| Posted: Fri Nov 14, 2025 4:26 pm Post subject: Re: Broken cam gear?! |
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This isn't the first time those gears with the oval holes have been reported to fail this way... I think I remember reading that the others that failed were cast? Maybe poor quality castings?
CB's are nice, much like the old Magnums. Pauter makes the best set now but $$$
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modok wrote:
Bent cranks are silent but gather no moss. I mean, ah, something like that. |
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RickS
Samba Member
Joined: May 05, 2005
Posts: 639
Location: Speonk, NY
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| Posted: Fri Nov 14, 2025 5:32 pm Post subject: Re: Broken cam gear?! |
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Competition Engineering makes really nice cam gears. This one is .100 oversized for a TF-1 case.
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BFB
Samba Member
Joined: November 03, 2014
Posts: 3082
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| Posted: Fri Nov 14, 2025 6:34 pm Post subject: Re: Broken cam gear?! |
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If you go CB , get the pro set gears. The crank gear has the spacer that eliminates the stock C spacer and you dont need eccentric washers either.
https://www.cbperformance.com/product-p/1400.htm
Bet OP was running too much spring for crap cast gear that might not have been cut right to boot. Who makes that thing?
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jim martin
Samba Member
Joined: January 14, 2004
Posts: 397
Location: Vancouver, BC
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| Posted: Fri Nov 14, 2025 6:52 pm Post subject: Re: Broken cam gear?! |
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Do your research by quality parts. Then take the time to learn how to check and install them correctly. Hopefully this won’t cost to much to repair.
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Last edited by jim martin on Fri Nov 14, 2025 9:56 pm; edited 1 time in total |
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txoval
Samba Member
Joined: January 23, 2004
Posts: 3887
Location: The Woodlands, TX
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| Posted: Fri Nov 14, 2025 9:39 pm Post subject: Re: Broken cam gear?! |
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In fairness, there are high quality cam gears available…the broken one isn’t one of them. It’s a cheap cast part.
CB Pro Series gears are loud as hell…just fyi
1399’s are my recommendation…quality and quiet |
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BFB
Samba Member
Joined: November 03, 2014
Posts: 3082
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| Posted: Sat Nov 15, 2025 10:58 am Post subject: Re: Broken cam gear?! |
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| txoval wrote: |
….
CB Pro Series gears are loud as hell…just fyi
…. |
Straight cut loudness is all a matter of opinion, i run the pro’s in 90% of what i build and not one person had said they were too loud. Personally i wish they were louder. They’re no where near as loud as the “noisey” gear drive in a SBC that i have
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"how am i supposed to torque the rear wheel nut to 250 ft lbs??? " - clonebug
An interesting thing happens in forums where everyone starts parroting the same thing and "common knowledge" takes over.
Most experts aren't. |
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daveblank
Samba Member
Joined: November 07, 2024
Posts: 241
Location: Dallas, TX
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| Posted: Sat Nov 15, 2025 11:31 am Post subject: Re: Broken cam gear?! |
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| BFB wrote: |
If you go CB , get the pro set gears. The crank gear has the spacer that eliminates the stock C spacer and you dont need eccentric washers either.
https://www.cbperformance.com/product-p/1400.htm
Bet OP was running too much spring for crap cast gear that might not have been cut right to boot. Who makes that thing? |
These are an option instead of the factory spacer. https://www.cbperformance.com/product-p/1919.htm |
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RickS
Samba Member
Joined: May 05, 2005
Posts: 639
Location: Speonk, NY
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| Posted: Sat Nov 15, 2025 3:15 pm Post subject: Re: Broken cam gear?! |
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Everyone uses a “racer spacer”, but has anyone ever seen a stock spacer fail? Not I. |
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Glenn
Mr. 010
Joined: December 25, 2001
Posts: 80372
Location: Sneaking up behind you
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| Posted: Sat Nov 15, 2025 3:21 pm Post subject: Re: Broken cam gear?! |
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| RickS wrote: |
Everyone uses a “racer spacer”, but has anyone ever seen a stock spacer fail? Not I. |
Same.
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Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"
Member #1009
#BlueSquare
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BFB
Samba Member
Joined: November 03, 2014
Posts: 3082
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| Posted: Sat Nov 15, 2025 4:51 pm Post subject: Re: Broken cam gear?! |
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| RickS wrote: |
Everyone uses a “racer spacer”, but has anyone ever seen a stock spacer fail? Not I. |
So?
Far as im concerned, why not use a gear with a built in spacer? Doesn’t cost any more and it’s one less part, matter of fact the pro set actually costs less than the set that would use a stock spacer. So there’s several reasons to use one aside from failure.
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"how am i supposed to torque the rear wheel nut to 250 ft lbs??? " - clonebug
An interesting thing happens in forums where everyone starts parroting the same thing and "common knowledge" takes over.
Most experts aren't. |
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Glenn
Mr. 010
Joined: December 25, 2001
Posts: 80372
Location: Sneaking up behind you
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| Posted: Sat Nov 15, 2025 5:52 pm Post subject: Re: Broken cam gear?! |
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| BFB wrote: |
| Far as im concerned, why not use a gear with a built in spacer? |
Who makes one?
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Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"
Member #1009
#BlueSquare
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