[Cloud9...68]

Flash,



Thanks - that was my interpretation, based on the posts in this thread. I wasn't seeing the physical connection between the belt job and the need to time the cams - I now understand it's just a mileage interval thing driven by the wear of the cam gears and chain. I haven't put many miles on my current set of belts - something like 2500 or so - but I bought the belts as part of the initial set of parts for my engine rebuild, thinking it would be done in a few months, tops. It took two years. So the belts were sitting in my room nearly two years before I finally put them on, it's been close to two years since I got then engine running, plus no telling how long they were sitting in the warehouse of the place I bought them. So, I figure it's about time to change them. But since the cam/chain gear wear is a mileage-driven thing, I'm quite a ways from needing to re-time the cams.



Bulti - The job isn't all that bad. There's a lot of info out there on it. You do need a pair of inexpensive dial indicators, some tubing (I used copper) to contact the cam lobes, and an air compressor.

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[KRAG50]

Cloud

If you are going to do a belt replacement ( I think you do it yourself right? ) do a measurement before then again after, you'll see the change first hand, then again after 5000 miles or so, again you'll see the change. Make sure you pressurize the vario cam with oil.

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[Cloud9...68]

Krag - That sounds like a good suggestion, but given the sources of error in the timing procedure itself, I'm not sure I could detect a difference I could believe, if in fact the impact of the belt is very small. I agree it would be a good data point to have, though.



Also, I don't know how to pressurize the varicam with oil. I saw the description of how you did it awhile back, and it struck me as being extremely complicated, using a bunch of equipment I don't have, and couldn't easily make or buy. Or maybe I was just too awed by what you did...

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[taporite6]

if you replaced both top and bottom pads should you just clean the adjuster or replace it

that's a $900 savings

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[flash]

it's a hydraulic valve. if it holds pressure, the consensus seems to be clean and reuse, however it is common for them to leak a bit, which would reduce the amount of timing advance when it kicks in. i reused mine, but my motor is supercharged, and i did my own timing maps, so the fact that it may leak a bit and not give me full advance was not an issue.

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[Bulti]

When time comes I'll give it a go. Maybe I could find somebody more experienced with the procedure who would want to help, so a proper DIY and required parts list can be added to the collection. It's really a must-have for 968Forums since it is so important.

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[Spyderman]

Well, finished the replacement of the timining and balance belts this past weekend. Made sure I triple checked all the camshaft, timing and balance shaft alignments before buttoning everything back up. Left the coil wire off the distributor while I cranked the engine a few times to get some of the fresh oil circulated through things, since the engine was idle for quite a while during all of this work. When I re-connected the coil wire, the engine fired within a second or two, and settled into a nice, smooth idle. No disturbing noises or sounds, as I controlled revs with the throttle cable from under the hood, so it would appear all's well. Will drive the car a bit and re-check things to make sure settings are still within spec.

                           

Some after thoughts:

• The Arnnworx flywheel lock - best $38.00 expenditure in a long time!
  
  
• When compressing the timing belt tensioner piston in my bench vise, I placed the box end of a 17mm wrench on the base end of the tensioner to protect the softer metal protrusion from being damaged.
  
  
• Patience is required when compressing the tensioner piston, as someone pointed out in one of the write-ups I referred to during this work. I gave the vise a small turn, went back to working on something else, and kept coming back to apply small turns periodically until the hole in the piston head was lined up with the hole in the tensioner body, at which point I inserted a small drill bit (smooth, shaft end versus twist end) to keep things in place while re-installing the tensioner.
  
  
• Getting the snap ring off, and back on, the timing belt tensioner lever assembly shaft was probably the most tedious part of this whole process. If you don't have a pair of snap ring pliers with 90 degree bends in the prongs, get some! Fortunately, I have a pair of Channel-Lock snap ring pliers with changeable tips, and had just the right 90 degree angled tips in the pouch.
  
  
• Taking one's time, and re-checking everything as you go, will avoid a lot of frustration and angst during this whole process. Even though this was the first time I've tackled this level of R&R job on this car, by following the advice and instructions of others who have performed this work, made this a lot less intimidating than it may appear to be.
  
  

A big thanks for all of the excellent information that others have posted on these processes here, and elsewhere. Made doing all of this work less intimidating, and provided a huge level of satisfaction in completing this work. Didn't hurt saving a few bucks either... <img src="/forum/images/smilies/968/wink.png" class="smilie" alt="" />

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[Bulti]

I assume you made the pics befóre you set the BB support idler to its final position? :-)

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[Spyderman]

Yep, just snapped a few photos during a lull in the action... <img src="/forum/images/smilies/968/wink.png" class="smilie" alt="" />

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[Cloud9...68]

Looks good. Did you confirm the tension in the top section of the timing belt, the part the goes between the cam sprocket and the crank sprocket, was nice and tight? When I installed my TB and just let it lay where it naturally wanted, it was too loose in this section, and in order to tighten it, I had to fabricate a tool to rotate the cam sprockt clockwise enough to engave the next set of belt teeth. Thanks to Bulti and Lear35A for this suggestion. From the picture, your belt looks reasonably tight. Did you have to do any work to get it tight, or was it pretty tight as installed?

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[Spyderman]

The timing belt tension 'felt pretty good' on initial installation. To get the cam sprocket teeth aligned with the timing belt sprocket teeth, so that the cam sprocket notch was going to line up with the notch in the upper metal cover, I had to turn the cam sprocket just a hair clockwise, and slip the timing belt teeth on the sprocket. After it was all routed, and the tensioner was released when I pulled out the drill bit, the cam sprocket notch was right where it should be. I rotated the crankshaft through several clockwise revolutions and rechecked the tension, and it was good to go.



I was actually very surprised at how all of the alignment marks lined up when I had both belts in place, prior to adjusting their tensions. The lower balance belt cam was the trickiest to get positioned properly, due to the limited physical and sight access down there. Had to use a mirror and a flashlight, and it took several iterations before I was satisfied with the alignment.

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[Cloud9...68]

That sounds perfect - I think you nailed it. Good job on your first go-around on this. And yes, getting the lower part of the balance shaft belt in place is one of the trickier parts of the job.

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[ds968]

I note you said in a previous post that you ordered Gates belts . Looking at the photos it seems they now come with all sorts of markings and advisories printed on them ( IIRC, they never had anything of the sort before, just the brand logo, a coded manufacture date and that was about it ..) wonder what made them put all those PSAs on their belts ..

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[Cloud9...68]

I was wondering the same thing...

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[ds968]

What is written on those ? " Do not use tools to pry on or off...." ? and " Never bend smaller than full...?? " - huh ?

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[Cloud9...68]

Strange - my Gates belt didn't have any markings on it, other than the Gates name brand.

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[ds968]

   



hmm, they should have this printed on them. at least on the timing belt, not 100% sure about the balance belt... the 6 digits after the part number show : - chronological day in the year, year's last digit, and the mfg plant code , I.E. 0868MC = 86th day of 2008 - MC is the plant

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[Bulti]

Lol, sure that's not a '68 belt?

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[ds968]

If it is, then it must be a new record for belt longevity, lol. I was joking with the folks at Gates ( exchanged some emails with them and also spoke to one of the reps about the quality and expected durability of their belts ) when I saw the numbers, telling them they made a terrible error coding the belts because the car is a 968, not an 868 !! I still find it strange they use the " X th " day instead of a typical day, month and year, or at least month and year, but that's how they did it..he explained why but I forgot. Anyway, if they still have those numerical codes on the belts when you order them ask the dealer to make sure they give you the ones with most recent mfg date which they have in stock.

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