johnu

Just in the middle of a TB job.
My cam gears are very worn (overtightened belt maybe?). I plan on replacing with new ones. Anyone have a link or a good explanation of how to remove them? Will I need a tool to adjust the timing when I put the new ones on?

thanks
John

Avar928

Do you have a picture of the wear? Is it shiny all over the teeth?

In the middle of my timing belt/water pump job and a better look at my gears shows that mine are still good. Perhaps 15-20% shiny on some of the teeth. I even bought new gears and everything intending to replace them but I'm not anymore.

johnu

oh ya....they are worn......

dr bob

The driving question is not how they look now, but if will they still have anodizing to protect the metal for the expected life of the belt you are installing. If they are already showing wear-through anywhere, they are due for replacement. No fair if you say that the belt will live a shorter life with the worn gears, therefore they will come off and be replaced together in just a few years.

Have your current barely-usable gears recoated by Colin (Lizard) and put them in your bin of spare parts, for the 50k after the next 50k.

ammonman

With the crank locked at 45degBTDC and the TB removed counter-hold the large hex shaped washer and loosen the retaining bolt. Remove the bolt and slip the cam gear off the cam. While the gears are off it is wise to remove and inspect the tri-armed hubs for cracks along with the camshaft keys and key ways for damage and deformation. Thread the cam gear retaining bolt back into the end of the cam before applying a small puller to remove the hub. Clean the hub bore and cam snout well before re-installing the hubs.

You will need to re-time the cam gears after installation. The Pk32Vr tool works well, is a good reasonably priced investment, and is much easier than the dial method from the WSM.

Mike

Leon Speed

There are many threads on this subject, search for "TB" or "timing belt". Dwayne has a good write up with pictures: http://dwaynesgarage.norcal928.org/1...0Procedure.htm

Basically you lock the crank at 45 BTDC, loosen the belt tensioner, take the belt off, replace the cam gears, put the belt back on, tighten the belt, time the cams (either a dial indicator on the cm lifters or buy Porken's 32Vr- the last one is much easier), remove the crank lock.

Naturally there is much to clean and to replace when you are in there, but by all means rebuild the tensioner. If it doesn´t leak it sure will later on and now you have good access to it. Alternatively replace with the Porkentensioner. I have no personal experience with it but people report good results.

ROG100

Remember old gears were made from soft material with a spray on wear coating and are prone to rapid wear.
New gears are made from much harder material and are showing zero wear - early days but so far so good.

dr bob

Roger--

Are your gears still in beta, or approved with final QC stamp attached? I have this little project to do in the next few months...

Avar928

I was planning on saving the gears for when I was going to change everything the next time. Guess there's no harm in just changing them out now and one of the local 928ers did lend me their 32vr tool and bump stick.

I've got Roger's new gears and they look fantastic https://rennlist.com/forums/928-foru...928-party.html

ROG100

Dr. Bob,
Been in use for about 18 months with over 20k miles on one set. Sold about 40 sets.
Roger

johnu

Thanks for the good info everyone.
Here are some better pics of my gears....let me know what you think.

My opinion....

PHOTO 1....Left side does NOT need replacing....

PHOTO 2...Right side definitely needs replacing...

PHOTO 3....oil pump gear does NOT need replacing...

PHOTO 4....Crank gear should be replaced...

everyone agree?

ROG100

I agree

johnu

Then get ready for an order

johnu

OK, one more question....
Looking at Dwayne's TB tutorial, it appears that he has ONE roller bearing below the crank gear....my car (1987) has TWO....am I seeing things or is this normal....I believe his is an early 1987 S4

ROG100

Two rollers were added later in 87 so you are not seeing things. If you are using a PKensioner (can't remember) you can get rid of it or leave it be.