First: Thank You to all who have contributed in earlier threads on the subject.
I rekon if the slack-side of the belt can be be calmed and get a bit better wrap on the alternator pulley, the tension can be reduced and belts & bearings will last longer.
The added pseudo-idler pully is simply a 150mm bolt with two bearings in tandem. The bolt needed a few extra threads to replace the stock bolt holding the alternator in the bracket. The bearings are from the tractor shop, so they needed a bushing to fit the bolt.
The belt shown is a 700mm cheapie, the 685mm is forthcoming. That should help provide more contact on the pulley's tension-side and give more potential for tightening as the belt stretches.
Time will tell how well it works...
EDIT2: updated title to reflect current mileage EDIT3: revised title EDIT4: revised title EDIT5: revised title EDIT6: revised title
Last edited by TylerDurden on Sat Nov 19, 2011 6:45 pm, edited 6 times in total.
Have a nice day.
'91 Jetta ECOdiesel TD - clean & complete (less motor/tranny) for sale
You may be onto something. Ever seen the timing belt setup on a newer 1999-2004 TDI? They have rollers like that between every major sprocket (Injection pump, cam, water pump, and crank).
I'm assuming it cuts down on deflection, which cuts down on wear.
I replaced the A/C belt with a Conti 947mm (it was a Bando 968mm). To get the Conti installed, I had to grind down some of the 1mm shoulder on the bracket. The shoulder prevented the compressor from reaching the bottom of travel. The Conti barely fit over the pulleys even then.
View from under the fender:
After tensioning the A/C, it was impossible to install the Conti 685mm onto the alternator. I went back to the 700mm belt. The tensioner pully now has ~300mm range remaining, and the A/C tensioner has about the same.
Another thing I noticed is grease on the surface of the new idler bearings. I suspect the bearings are merely shielded, not sealed. They will be replaced.
Regards...
Have a nice day.
'91 Jetta ECOdiesel TD - clean & complete (less motor/tranny) for sale
Does your AC work, and if it does, do you use it ever? If it were my car, I'd remove the compressor and get the proper extended pulley for the alternator and do away with it altogether. You can fashion a bracket for alternator tensioning very easily.
Ah cool. Yeah, I'd delete the AC. The pulley you need can be hard to find short of going to a junkyard and finding one like yours w/out AC but bosch dealers and any reputable alternator shop can get you the pulley.
I had to fashion up a tensioning bracket on mine when I deleted AC but all it took was a bolt, a few nuts used as spacers, and that was it. Well worth it. And my belt problems disappeared. Luckily, my 91 came stock w/out AC so I didn't have to worry about that stuff.
just a plug for removing the ac and ps.... i love it. steering has better road feel without the pump going and the system cools remarkably better without the ac condenser in front.
i'll bet that your front end isn't high... your rear is low. i was able to perk the rear end of my 91 jetta up by placing large diameter washers between the spring seat and the spring. i get a ton more suspension travel, can carry 14 gals veg oil and a several toolboxes for work without drooping. it has a look a bit like the jacked up cars in high school, which makes me feel young
I plan on performing the tensioner adjustment with the suggested bearings and longer bolt set up. How has it worked for you? Any suggestions now that you have been running it. Any updates that you may make available?
I like the setup a lot. $30 ain't too bad for a nice aftermarket tweak that cuts down on the troubles of reinstalling new belts a couple times a year...
Are you still considering deleting the AC? Even up north the summer isn't always so kind. And with your new setup, I'd counter COKE and say go all the way and get that AC blowin' ice cold!
For me it is as much for the reduced stress on the alternator bearings (from over-tension), as it is for the belt annoyances... Less tension needed for adequate grip.
It looks to be running pretty smoothly, but I presume there are still belt vibrations. It may be simply that putting a node in the path divides the vibration into two sections of partial amplitude.
I will keep the AC and have it leak tested in the spring. I like AC almost as much as most folks, but can live without it. This season I'm more interested in better heat. ::embarrased::
I am inclined to agree with DanHoug on the rear springs... I had two passengers in the rear seat and the back end was quite low. I reviewed the posts regarding spring alternatives and still am not sure what direction to go.
Have a nice day.
'91 Jetta ECOdiesel TD - clean & complete (less motor/tranny) for sale
I bought the two bearings and the set of five bolts from Grainger Suppy and found the bolt to be very difficult to thread in completely. I have an inch of the head bolt unable to thread all the way in. I even tried using a breaker bar, the bolt threaded in nicely early on but gradually became impossible to tighten all the way in. I did manage to have enough bolt to add the two bearings and a nut with a washer. Hope it fixes my problem, any suggestions of why the bolt would not thread all the way through?
