In another thread I showed many closeups of the rare Porsche 9131 t-belt tension checking/setting tool. As many of you know, this tool is no longer available and the very capable and similar Kempf tool has taken its place with more than a thousand sold. The other relatively well known tension measuring tool is the Porsche 9201. In photos that follow, I show all three.

In short, the measurements that I took with the P9131 and its spinoff, the Kempf tool were very similar. Directions for use of the former tool are found in the 928 Workshop Manuals. It essentially works just like the Kempf tool and gives similar results. I find that the P9131 does not flex open (side to side) like the Kempf tool but this is of no consequence to the infrequent user. I think repeatibility of measurements of the P9131 are a bit easier but not enough to be concerned. Last time I checked, the Kempf tool was about $60 or so, a necessity in any 928 tool box.

The Porche 9201 tool is the $400-$650 tool (depending on where you buy and if used or new) and has a precise dial gauge built into it. While it's really the most accurate of all the tension tools (and more versitile), it's also the most difficult to use on the 928 t-belt. The problem with getting good measurements with the 9201 is the cramped working space and the really poor viewing angle of the dial. If you twist the belt just a small bit (easy to do), it changes the dial indicator reading quite a lot. That aside, in the hands of an experienced operator, this is the most accurate tool.

On the alternator belt, the 9201 is easy to get dead-on, repeatable settings every time because of easy access. It's not so much the gauge but the operator's experience in finding the sweet spot and getting T-belt readings that are consistent. I spent 3 hours playing around with the 9201 before I felt comfortable that I had it pretty well figured out…and even then, I still make several repeatable measurements before I'm satisfied (that's a lot of turning the crank before each measurement). Your experience may be different but, for me, the Kempf Gauge was always at the upper end of the "window" as compared with the 9201 setting of 5.2 on my 32V 928s. I think there must be some belt tolerances in the 928 that allow for OK settings in the middle of the Kempf window on most 928s, although I've heard that the Kempf tool was originally made using the 16 valve car. With all the happy users out there, from middle to high end of the window must not make a difference or we'd all be hearing about it on the forum. On the low end of the Kempf window, I feel that you will have too low a setting (at least too low for me)...but that's just my experience on 32V cars. BTW, I've checked the Kempf gauge against 3 different 9201 tools (OK, so I'm ****).

My method is to initially (and quickly) set the belt tension with the Kempf gauge….then double-check it several times with the 9201 for any fine tuning if needed.

I don't think anyone would argue that the 9201 is difficult to use on the 928. The Kempf tool (or the Porsche 9131) is by far the easiest and adequate for the job. If I were having anyone else work on my car…I’d trust their use of the Kempf gauge much more than their use of the 9201…unless they were a highly skilled mechanic and used the 9201 regularly on 928s in their work. Even then, if they get in a hurry, they could get a wrong reading.

I've seen the Kempf Gauge and the 9201 listed for sale in the 928 International catalogs. I suspect that 928 Specialists sells them too.

Harvey

 

Nice write up and pics H.

I was fortunate enought to have Capt. Earl check my TB tension when I picked up my '88 on the east coast (thanks to rennlist for pointing me to him while I was out there searching for a fuel pump, but I digress...).

We used his fancy 9201 tool, and it was a bit tricky, even for Earl, and Earl knows his stuff. It is super accurate though.

I had my Kempf tool with me, so we compared readings, which was great because I was a bit leary of the Kempf tool.

But, my Kempf tool checked out very nicely vs the more expensive Porsche tool.

I did find that my Kempf tool did read right on the highest side of the Kempf window when the Porsche tool said I was right on the correct setting.

So I have a baseline for my particular Kempf tool.

Sa-weet!

 

That's the experience of many 32 Valve 928 owners. I filed a mark in my tool so I'd know where to adjust to. If I remember right, at the middle of the window I was getting 3.? reading. Works but it's kinda on the low side. At least that's my experience. I'll be pulling a cam gear and checking the Tbelt again in a week or so, I'll double check it if I can remember.

Harvey