Tom. M

So far three cars with the belt tracking forward..was the result of the circlip missing on the tensioner roller. They never come with a new one..and many have been left off. An 84 we just did was missing it..and although the belt was OK. it was obvious the roller was tracking wrong. Look in the manuals..the diagram clearly shows the circlip in the groove of the shaft of the roller. It is used to position the roller out a bit and keep it in line with the tbelt. My GT had the same issue last Track Attack..hard acceleration would set off the light and no amount of adjusting would cure it. It was at that point I took it all apart and found that the circlip was gone..

Good Luck..
Tom
89GT

Bill Ball

Jay really agreed that the center is 3.0 and we should be at the high end fo the window? I've always set belts just slightly above center and have not had any problems. I do it the way borland mentioned - TDC, set, rotate two times to TDC, check, repeat a few times.

If Jay has changed the way the tool should be used, that word should get out more widely.

Ben

Tom, I made sure I swapped the circlip over, so that cant be the issue. Maybe its like Mark says, and i'm missing the washer for the pivot bolt. Its not riding over the edge, but its close.

So is where I have the tension set to ok? And is the wear on the back side of the belt excessive for only 50 miles? The belt I took off had no printing left on the back at all, but still looked pretty good.

H2

Jay did not agree on the 3.0 setting...that was approximate and was my and my mechanic's experience with more than one Kempf tool and more than one 9201 tool...with calibration bars. I'm sure that most 928s would work OK at the middle setting... Jay developed the tool on the pre-'85 Porsche. There must be some slight difference?

A search of the archives will reveal several discussions of this and I'm pretty sure that Jay chimed in with his analysis on one or so of these.

Most who are acquainted with this agree that the HIGH side of the Kempf slot is closer to 5.2 for post '85 cars....but, as I said, Jay hadn't really had a lot of complaints about the tool from anyone when I talked w/him. When I got the low reading, I sent my tool back to Jay, he made sure it was within his spec and sent me another...both the same. He couldn't discern a problem. Very nice guy, btw.

Don't take my word on something this important. Check the archives for this discussion and I'd suggest have your tool checked against a 9201 if you have a 928 later than '85. Apparently, there are lots of factors affecting belt tracking and there must be quite a bit of latitude on tightness....only a very tight belt will prematurely wear out stuff, and a loose belt will trip the Tbelt light easier. I get worried when the light comes on. Properly tensioned, I never have Tbelt light problems. Pre 9201, I frequently got tbelt lights.

I just filed a mark into my Kempf tool and that's what I use to get my settings...with two rotations between checks. I'm **** about checks and don't stop until the 9201 verifies the Kempf setting. I'm now so confident in the recalibrated Kempf setting that there really isn't a great need for the 9201....once you verify the Kempf. BTW, I always put a light oil on the Kempf connection pin each time I use it.

Interestingly, there is no real comparable tool for the 944/968 as the Kempf. The Kricket (sic?) is used but it's generally agreed that it's not terribly accurate. Jay did a much better job with his tool.

Since Jay really hasn't had a lot of complaints w/the tool as is, this may not be something he relishes discussing..but I can't speak for him.

Check it out...I'll bet you end up agreeing with me.

Harvey

ROG100

Borland,
"I think most mechanics misuse the Kemph tool. This results in belt warning lights and possible overtightening of the belt. The tool is accurate, but requires belt only be measured while the engine is at cylinder #1 TDC.

Also, after any adjustment of the tensioner adjustment screw, the engine must be hand cranked two full revolutions until the engine is again at cylinder #1 TDC, prior to rechecking the belt tension with the tool."

Now usually I am with you 100% on what you say but in this case I am going to offer a different opinion.

The last 4 or 5 cars that I have changed the TB on I have checked the TB in every position including TDC at No 1 cylinder and found every measurement on the kemph tool to be the same no matter how many times I spin the engine.
So why is the measurement at TDC so important if there is no difference any where else in the spectrum of checking?
Interested in your opinion please.
In every case I have gone by the book and set the kemph tool in the middle of the window and after wards got the TB light.
Once I change it to the tight side of the window everything is fine.
I use a number of different Kemph tools and the readings are always uniform.
Sorry to disagree but the proof is in the pudding.

H2

Rog,

I agree that Jay has good quality control on the Kempf tool...from tool to tool, but that the more accurate setting for the post '84 cars is closer to the top of the window than the middle. With a fair, side by side comparison with a properly calibrated 9201 ( by someone who knows how to use the 9201) I think anyone would agree.

The bigger problem, I feel, is that, while the Kempf tool is easy to use and replicate/take readings, the 9201 is a PITA to get right and the space is hardly enough...and the way to use the 9201 in some directions that I've seen is incorrect (can't be done the way explained). That's where the machinics would most likely mess up, I feel, is in taking an accurate 9201 setting.

I'd love to be proven wrong... but I gotta see it to believe it. I spent a lot of time on this once before and it would take a lot to un-convince me given the hours spent on this. Really, the 9201 is very difficult to use accurately on the 928..but the Kempf is a piece of cake.

Someone, please, prove me wrong.

Harvey

Garth S

When using the Kempf tool, I too am a methodical follower of - measure at TDC, and do two full rotations following each tensioner adjustment'. I have not been able to reproduce consistent readings at points other than TDC ... and have speculated that to be an effect or contribution from valve spring pressure attempting to torque the cams off the set point - an effect that appears more pronounced if cylinder pressure builds due to my lazy wrenches not first pulling the plugs ( and opting to use more brute force to crank the engine over).

Also, once the TB is correctly timed, I have found that by rotating the engine at least a dozen turns prior to the final tension setting appears to mate the new belt to the cogs better ( an alternative explanation is to "allow the belt to do its initial stretch") .... and more quickly allows the desired tension to be set and confirmed on the following pair of rotations.

The only belts I have had to retension at ~1000+ Km due to alarms ringing in are every brand except Optibelt

mark kibort

I'm pretty good at the porsche tool. the only variable here, is that this porsche tool i have used has not been calibrated in a while, but its from a shop. Ive calabrated the Kempf tool to be like we all have seen here. 3/4 of the window gives me 5.0 on the porsche tool.

Mk