Lagondaforum » Engine » Block, Head and Internals » New fibre timing gear too tight in mesh!

h14	May 17, 2009 1:15 pm
Subject: New fibre timing gear too tight in mesh! Hi...I bought 2 new gears (1 & 1 spare) for my V12 around 1980. Now the engine is finally being rebuilt, the guy tells me he's tried both in place, & that they're so tight in mesh, he's reluctant to use either of them. He says he's heard that in certain circumstances, fibre (tufnol) can "grow". Main question has to be...is tight mesh likely to be an issue, or will it bed in quickly with use, to good tolerances? I understand duralumin replacements are available...however this is a late Sanction 2 engine, therefore fitted originally with a fibre gear, so it therefore doesn't have spray bars fitted to lubricate these gears (as the Sanction 1 engines with bronze intermediate gears did). Also reluctant to fit metal gear because of extra noise, & also like the fact that a fibre gear will strip before anything else breaks! So...any thoughts/advice gratefully received!

h14

May 17, 2009 1:15 pm

Subject: New fibre timing gear too tight in mesh!

Hi...I bought 2 new gears (1 & 1 spare) for my V12 around 1980. Now the engine is finally being rebuilt, the guy tells me he's tried both in place, & that they're so tight in mesh, he's reluctant to use either of them. He says he's heard that in certain circumstances, fibre (tufnol) can "grow".
Main question has to be...is tight mesh likely to be an issue, or will it bed in quickly with use, to good tolerances?

I understand duralumin replacements are available...however this is a late Sanction 2 engine, therefore fitted originally with a fibre gear, so it therefore doesn't have spray bars fitted to lubricate these gears (as the Sanction 1 engines with bronze intermediate gears did). Also reluctant to fit metal gear because of extra noise, & also like the fact that a fibre gear will strip before anything else breaks!

So...any thoughts/advice gratefully received!

Julian	Jun 24, 2009 10:50 am
Subject: Re: New fibre timing gear too tight in mesh! Hi, My advice is to use the Ally gear, it makes no noise etc and you really don't want a weak link in your valve timing gears! There is easily enough oil in the timing chest to lubricate your gears. Regards, Julian.

Julian

Jun 24, 2009 10:50 am

Subject: Re: New fibre timing gear too tight in mesh!

Hi,
My advice is to use the Ally gear, it makes no noise etc and you really don't want a weak link in your valve timing gears!
There is easily enough oil in the timing chest to lubricate your gears.

Regards,
Julian.

h14	Jul 10, 2009 10:05 am
Subject: Re: New fibre timing gear too tight in mesh! Hi Julian, Many thanks...but have found a gear cutter who says he can shave the gears (I have one & a spare) to the correct profile. Wouldn't exactly call the fibre gear a weak link...the original in my car lasted 36 years, & even then probably only failed through oil starvation...my engine was missing the vibration damper, which throws oil up to these gears. Cheers Laurence

h14

Jul 10, 2009 10:05 am

Subject: Re: New fibre timing gear too tight in mesh!

Hi Julian,

Many thanks...but have found a gear cutter who says he can shave the gears (I have one & a spare) to the correct profile.
Wouldn't exactly call the fibre gear a weak link...the original in my car lasted 36 years, & even then probably only failed through oil starvation...my engine was missing the vibration damper, which throws oil up to these gears.
Cheers

Laurence