Gentleman Driver

Good afternoon Rennlist,

When my mechanic did the cam tensioner guide maintenance, he noticed that my balance shaft belt was shredded even though they were both replaced about 10K ago (presumable because it was the wrong size). I have been running it without the belt, honestly didn't even notice a difference, but I have a track day that I want to do and I am worried about overall wear due to the 100K+ miles and the extra beating the car will take from the track (motor mounts, etc).

So, my question is, do I replace just the balance shaft belt since the timing is in good condition (according to my mechanic) or do I do all the belts and rollers (and front main seal, because it has a slight leak).

I ask because I don't think I could do all of the above myself (tools required, novice ability, etc), but the cost for my mechanic to do all of it is $1K+...

What do you think? Just replace the BS Belt myself? Run the car without the Balance Shaft in action?

As always, I greatly appreciate your infinite knowledge. :-)

RajDatta

I would not run the car without the bs belt. Was the old bs belt 15mm wide or the updated 18mm? Also, what brand was the bs belt. It important to use the factory bs belt. If the timing belt did not get touched, I would leave it alone. Also, if you currently don't have leaks, I wouldn't mess with front seals. Save it for your next timing belt job.
Raj

rdhayward

And I would recommend following Raj's recommendations!

Gentleman Driver

Cool, I always do what Raj recommends!

So, the big question is, can I do the Balance shaft belt on my own, or should I take it to the mechanic who already has all the tools, experience, etc? I have done the accessory belts, and a whole lot of other parts, but this appears to be a step up and requires additional tools.

I think we said it would be ~$400 for the balance belt and tensioning...

Cheers

Luis de Prat

I just did both belts and the 5 rollers on the S2, which is a very similar engine. The balance belt really isn't bad, but it's getting to it in such a way that you can properly tension it that is. Meaning, remove engine protection pan, cooling fans, accessory belts, airflow meter, etc., etc.

For me the hardest part was removing the crankshaft pulley, and getting the cam belt and autotensioner on, which you won't have to do, so if you have a little time on your hands you might consider DIY. Also, the balance belt tension isn't critical, so eyeballing it would probably work although I used the Arnnworx P920X tool to set the tension.

RajDatta

I say, give it a try yourself. Worst case scenario, you can take it to the guy. It does require tensioning but besides that, no special tools.
Let us know if you need help in any way.
Raj

Gentleman Driver

Agree, think I may just give it a shot! Can you point to a DIY by chance? I have searched a lot and most decriptions are for both belts, not just the balance...

Thanks guys! A little worried about removing all of the accessories and fans, etc, but I have been just jumping into other projects, so this will be no different.

future

My old CS BS belt after only 1.5k on track only, pic taken about 6 years ago (I'd never run covers again):



I changed water pump, all belts and rollers at the same time all tensioned to spec.

RajDatta

GD, how soon do you need a write up? I am kinda busy the next few days but can walk you thru it over the phone if it helps. I am sending you a pm with my contact. It might be much easier that way.
Raj

Gentleman Driver

Raj, would greatly appreciate just a talk, thanks!!!

FRporscheman

To remove the BS belt only, you can read through step 13 here:
http://www.clarks-garage.com/shop-manual/eng-05.htm

To install, you can read this and skip the steps you don't need:
http://www.clarks-garage.com/shop-manual/eng-06.htm

The only trick is that you might need to do some prying and twisting to get the BS belt onto the crank - I can't remember right now. GL

RajDatta

It's best to remove the crank pulley. You can leave the timing belt/pulley on since its the furthest in. You can remove ac pulley and bs pulley off as 1 piece, no need to seperate (another trick to save time) them. Place the new bs belt on the bs belt pulley and slide it back on. You will need a 24mm socket and a breaker bar to remove the main crank bolt. If you try to twist and squueze the bs belt thru, you might damage it.
Use antiseize on the crank rod the pulley slides on for ease in future removals.

Raj

FRporscheman

Yeah the antiseize works great. I just did a belt job and now I also think the crank pulley must come off. I have the harmonic balancer pulley from the S2 so maybe a regular 968 pulley will allow more clearance, but for me there was no way to install the BS belt without removing the pulley.

B Hayes

I am in need of some help. I have both 944 turbo & 968. The question, are these both timed the exact same? I recently took my 968 in for some work (belts etc), now the engine vibrates like crazy. I believe it to be the balance shaft, but per the mechanic, this is not the problem. My car has never had an issue with vibration, which is why I ask. They showed me the inspection point at the bottom of the flywheel and the matching balance shafts timed spot-on with the cam sprocket at TDC. There is a link a few posts ahead of this to Clarks Garage which shows the inspection point at the top of the flywheel, and I have a link to some manuals on-line that show the other location (see page 61). I am familiar with the Clarks Garage version, which I have used on my turbo. Please see attached.

[Bhttp://www.cannell.co.uk/968_Workshop_Manuals/968WRKSP.pdf[/B]

I didnt get a chance to see exactly what was on the flywheel through the inspection point shown and can't confirm it was the line shown. I am not sure if there are other marks on the flywheel that could have been confused with the marking showed in the illustration. Regardless, my engine vibrates like crazy, and the mechanic stands firm they are correct.

Any help is appreciated.

Thank you!

FRporscheman

First of all, the flywheel mark you're used to seeing on the 951 does not exist on the 968. Don't ask me why... But the only flywheel mark is on the back of it, which you can see from the front of the car looking backward, through a tiny peek hole on the flywheel cover.

Assuming the camshaft is timed properly (the engine runs smoothly and has good power?), then you can use the cam timing mark to find TDC.

With the engine at TDC, the balance shaft sprockets need to be timed, but make sure that the sprockets were installed correctly in the first place. There are two ways to install the BS sprocket. The right way and the wrong way!

The lower shaft should have a little "O" visible in a slit. The upper shaft should have nothing in the same slit.

What kind of engine work did your mechanic do?

I don't care how adamant your mechanic is. With all due respect to him/her, if you took the car in with no vibration, and you got it back with vibration, they did something wrong!