First belt change, some questions

Airdale · 12-28-2003, 06:14 AM

Hope everyone had a good Christmas! I just finished my very first belt change (I think) and have some questions/concerns as this being my first, I want to make sure I got it right and you know how things can go when you make "assumptions". I followed all procedures using the Porsche factory manual, Clarks garage and Blazak procedures. My forum search didn't help much so Here we go...

1. My 84 had the 15mm balance shaft belt and I received/installed the newer 18mm from pelican. Are the tensions the same for both? I used the optibelt from blazak and was getting good consistent readings (must have done it 100 times!) He has it marked for 40 and thats what I got.

2. The balance belt idler/roller calls for 1mm preload on top between belt and roller and .5mm gap between it and the lower balance shaft sprocket. This was somewhat of a bear because it seemed no matter how I positioned the idler/roller the only way I could get the .5mm gap was when the roller had about 1 to 1.5mm gap between the belt and roller. Is this correct? When I initially opened her up the roller had no gap and was actually pushing up on the balance belt (a little) and I had a HUGE gap between the roller and lower balance shaft sprocket. Definitely NOT the .5mm prescribed! Okay, I'm getting too wordy here so my question is, Am I okay or should the roller be contacting the balance belt? which is more of a concern, contact with the belt or the .5mm gap? My rollers are in the correct position and I have checked everything several dozen times.

Sorry for the long post but I am a bit nervous about this and know you guys can steer me straight. As far as the optibelt goes, I know there are pro's and cons on it so try and be gentle when you consider flaming my butt! I'm a 27 year aircraft mechanic and realize, that and $3 will get me a cup of coffee at Starbucks! ANY feed back is always appreciated! Thanks! Pat

Airdale · 12-28-2003, 06:18 AM

I'm such a Dork! Thats 28 on the balance belt not 40! I did tension to 28 not 40. Just got the two mixed up during my post.

Pat

SoCal Driver · SoCal Driver's Garage

Supposed to be a gap between the smooth face roller and the belts. Not a pre load. The Roller is there to keep the belt from slapping. Think the instructions you have suffered during translation.

Designers anticipated loose belts. Same with the updated water pumps. The fixed roller on the long reach of the timing belt was ok for one direction but Porsche found that a loose timing belt would hit itself at the water pump pulley and tear teeth off. So the separator/fence was added.

Airdale · 12-28-2003, 06:35 AM

Thanks SoCal, I knew you'd be out there! So from what your saying, I got it right? I have a .5mm gap at lower balance shaft (top of belt tooth to bottom of smooth roller and about a 1mm +/- .5mm between the belt and the top of the roller. That term "preload" can be misleading. I feel better already, well, I'm getting there. Thanks! Pat

SoCal Driver · SoCal Driver's Garage

Did you get the "package" I sent?

Airdale · 12-28-2003, 07:12 AM

Yes! I thought I had e-mailed you and let you know? My apologies for not doing so! Many, Many thanks! It will get A LOT of use! I've replaced the front wheel bearings/seals as you had recommended. New rotors and pads on the front also. Currently have the rears apart awaiting new bearings and pads also. Rotors look real good in back and will have them turned for the new pads. Replaced the radiator mounts, nice and tight now! two new front tie rod assemblies, had some pretty good slop at the steering rack ends. Having a lot of fun getting her ready for spring, believe it or not! Thanks again, your "Package" is helping a lot AND keeping me out of trouble! Have a SAFE and happy new year! Pat