Serge944

Alright, what do you guys use to tension your cam and balance shaft belts?

Serge944

Ive debated with several people before, and it all comes down to "its your risk." Well, today is my 2nd belt change; both of which i have done without using a tool to check belt tension. Heres my explination for my method, correct me if im wrong.

First, whatre the criteria for belt tension?

1. Must be tight enough so that it doesnt hit the plastic housing. If the belt is too loose, itll tap the plastic right below the cam sprocket when the air is being compressed. This is because the half which is doing the actual pulling takes away all the slack from the entire belt. If the belt is tight enough that it has .5 cm or so clearance between it and the plastic housing, there is no way in hell it will skip a tooth. Unless you did somehting else wrong.

2. Belt tension must be loose enough so that when the engine is at running temperature, the expanded aluminum wont put too much stress on the belt. Again, just follow the above procedure and it will be loose enough. Because you cant make it any more loose without encoutering problems. You might mention the difference in timing the extra slack might create....this is VERY minimal as even the tiniest change in lenght from sprocket to sprocket will have a relatively large effect on the tension. Hence, a slightly loose belt wont impact the timing.

The problem you have to avoid is overtensioning....when the belt is too loose, itll let you know because it will be hitting the plastic housing.

Finally, i am not aware of the exact procedure for using the factory of kriket tension, but you must understand that at various points of the crankshaft spinning, the majority of the tension will be transferred to one or another part of the belt. Hope this isnt just another blatant comment...but you have to be aware of the piston location when retensioning your belts, as you might be either tensioning the tight or the loose end of the belt.

Due to these variances, and that the tensioning tools possibly arent exact all of the time, i feel that with a little bit of common sense, belts can be tensioned by hand no worse than with a tool.

Feel free to correct me if im wrong somewhere, im only 17; so what the hell do i know, right?

944Play

I use the built-in spring tensioner for the cam belt and go by touch and sound for the balance belt.

Joe Jackson

First off, I think the biggest issue with timing belt tension is not how people set it initially, but that they do not go back in and RETENSION the belts after 2k then 15k then 30k (or replace at 30k like me). Those belts get loose after all those miles regardless of how tight you make them initially.

With that said, I just wanted to make one comment about your post. B/c of the counterclockwise rotation of the engine and the fact that when you rotate the engine by the crankshaft when tensioning, the majority of the tension on the timing belt will always be along the top of the timing belt (where you measure tension with any of the tools). This is b/c of the torque exerted by the camshaft on the belt. Like you said, at different piston heights (actually different valve positions if what does it), the tension will change hence why the factory specifies setting the tension at TDC and nowhere else. They also specify to rotate the engine counter-clockwise 10 degrees then set the tension. What this does is it distributes the tension from the top of the timing belt to the other side (which runs the waterpump). What this does is effectively gives you the tension reading of the belt on the waterpump side when the engine is rotating clockwise.

If you've had success doing it "your" (your meaning factory tool, Kricket, by hand), then there's no reason to change. I personally have heard of enough belt failures from improperly tensioned belts that I will continue to use the factory tool which I've had success with. I'll also continue to replace my belts early b/c they are so cheap it's pointless not to (if you are providing your own labor)

Sorry for the long post.

Serge944

Oh definitely, a belt job is so simple! Remove airbox, distributor, fans, PS and alternator adjustment links, and the plastic covers. Took me 2.5 hours (i didnt change the seals or rollers as they were still new). I changed mine after 10k miles since i started with a slightly used (and obviously broken in 2k miles belt). The belts and rollers were off the engine my car came with (broken rod) and i put them on the new engine i aquired. Basically, im planning on putting new belts on every 15k. If im already in there doing the tension check, might as well change it.

SoCal Driver

A badly tensioned NEW timing belt is better than a questionable old timing belt.

NeedPorscheSpeed

In the past, I have always taken my cars to my mechanic. However, from now on, I am either going to invest in a Kriket tool or do it by touch. One things is certain, though: I'm going to be doing it myself! Oh, the empowerment felt by self-wrenching!

BruceWard

I am going to do a Krikit vs P9201 next week. But if it were me and I had a 944 I would borrow / rent / buy a P9201 for the timing belt change. I think the risk is too high.

I did use a Krikit for the balance belt on my 968 when installing. I am using a borrowed P9201 for the retension. On the 968 only the balance belt has to be tensioned. The timing belt has a sealed oil filled auto tensioner that cannot be adjusted. I feel that on the 968 since only the balance belt needs to be tensioned the risk is reduced, however you certainly need to inspect reguarly to make sure the balance belt does not fail and cuase the timing belt to fail.

Serge944

What risk. Kriket will do the job. Besides, what makes this different from any other aluminum engine or belt...

FSAEracer03

The fact that it costs more than I can afford if the belt decides to separate due to my f*** up

I for one am looking forward to the P9201 vs. Kriket test. I was hoping to do one myself this summer at the shop, but couldn't get my hands on a Kriket in time. If they turn out to be similar, I will go out and buy a Kriket the following day!

Serge944

Simple solution. Dont f*** up.

Porsche-O-Phile

I've seen it done reliably by feel the "twist 90 degrees" method, although for my own peace of mind, I'll use a tool of one sort or another. I have the Kriket tool, I'd LIKE a 9201, but I'm not about to blow $600 on one.

IMB951

Sweet thread!! I just retensioned my belts with a borrowed P9201 yesterday!

ahofam123

My neighbor was a Ferrari mechanic, so I let him tension my belts by hand for my first belt change. For all of my retensions, I have used the kriket which has given me consistent results and no bent valves. To reiterate what has been said above, it is imperative that you rotate the crank properly in order to distribute the tension.

dgz924s

9201 used here