V-belts for 3.6 single top pulley conversion - your experiences, please!

[BarryJB]

(Earlier single pulley posts seen here - or better in 964/993 areas?)

Re: '95 64.07 993 in my '85 Carrera, PM single pulley conversion & stock lower triple (for A/C).

Belt started squealing tonight (just slipping), it's only been a few hundred miles since 3.6 was put in, and is worn on sides, really loose, and looks too narrow for and deep into both pulleys. Not just an adjustment needed... Drat!

Questions... any answers appreciated!

1. Since one belt drives fan & alternator:
- Is premature wear to be expected over stock 2-belt setup?
- Is a wider belt helpful? Say 10/12.5/13 x 775 - to increase contact patches
2. Any brands/types better than Genuine Porsche (e.g., Kevlar v-belts) for this specific mod?
3. Should stock 993 2-belt setup tension settings be used, or other? (in kg):
Old belt: 15–23 cold; 20–28 hot;
New belt: 23–35 cold; 28–40 hot.
4. Anyone recommend the Gates 91107 "Krikit" tension gauge for getting these NADI spot-on?

(Present belt is 999.192.338.50, "PORSCHE" & "9.5 x 776" on part, concurs with 64.07 fan-pulley belt in 993 parts list.)

Oh the joys of a new 3.6 convert
Cheers,
Barry

[spuggy]

Originally Posted by BarryJB

4. Anyone recommend the Gates 91107 "Krikit" tension gauge for getting these NADI spot-on?

Ha, that takes me back to when I ran a 944...

Timing belts are CRITICAL on 944/951's (and 928's). Breaking a belt or skipping a tooth means a motor swap or costly rebuild (involving at least some valves, pistons) - that will cost more than many 944's are worth...

These should be re-tensioned every 15,000 miles, and replaced every 30,000 (because enough belts have broken before the replacement interval of 45,000 miles that you don't take them that far).

The factory cam belt tension gauge costs $600, the Krikit, at the time, was $40...

The controversy as to whether the Krikit was accurate enough raged on (and on) in the 944 forums; at least a few folks who owned both the factory tool and the Krikit checked the tension with both back-to-back and said that it was accurate/repeatable, so long as you got a good reading. (Even with the factory tool, you take the reading multiple times).

I'd personally use one without hesitation for a less critical purpose than a cam belt - has to be better than gauging tension with your thumb or the Mk1 eyeball.

[BarryJB]

Originally Posted by spuggy

...The factory cam belt tension gauge costs $600, the Krikit, at the time, was $40... ...I'd personally use one without hesitation for a less critical purpose than a cam belt - has to be better than gauging tension with your thumb or the Mk1 eyeball.

Thanks Spuggy, plus they're only $13 now (various sources); I'll treat that as a thumbs up for at least v-belts then.

[Jack Olsen]

What's the correct tension spec for a single belt?

And since there are a lot of krikit tension gauges out there, which is the best for this application?

[BarryJB]

Originally Posted by Jack Olsen

What's the correct tension spec for a single belt?

And since there are a lot of krikit tension gauges out there, which is the best for this application?

Geez Jack if you don't know tension, maybe no-one does. But that's a part of my concern & question too.

Gates 91107 (also known as "Krikit" or Gates Model 1 - these things have been around forever (50 years?) 15-75kg - the bigger one is Gates 91132 50-140kg.

$12.90-something to order in store (1-3 days) or on-line O'Reilly's & CarQuest et al (Sears too for more $ - not PEP boys though); or you can pay up to $40 if you want .

There's a helpful Gates video at Dayco Krikit Tension Gauge - YouTube
vbr

[BarryJB]

Originally Posted by Jack Olsen

And since there are a lot of krikit tension gauges out there, which is the best for this application?

Re "best" - I didn't mean to suggest I know it's the best possible gauge for p-cars - just wanted to know if others here concurred that it was indeed an acceptable/useful tool - like Spuggy said, better than a thumb or eyeball. But the 91107 is the model that seems most popular with automotive DIYers for general v-belt apps. For timing belts I'd assume a different model is required.

No go dealer today, finally found something at PEP Boys, a US-made Dayco 15305DR/10A0775 - 10x775 - which took all the shims to give ≈1/4-in play (gauge arrives next week) but looks good and takes care of things for now anyway. And wow, easier change than on a 3.2! Just a 24mm to hold and rotate the shaft while you fiddle with the three nylocs. It must be a nightmare with two belts to finagle.

Old PORSCHE belt was also Dayco, made in Italy. It had deeper "teeth" on inside; the new one had shallower ones on OUTSIDE.

Since the alternator pulley was outside, we lost the higher-sideload-on-shafts/bearings effects of that 2nd belt's tension, plus isn't the 964/993 alternator higher output/more load, so does that imply a higher tension for the single conversion would be both OK and desirable, if the belt can handle it? For the 3.2 9.5x710 belt tension spec, I only ever saw "4mm" - anyone have a kg figure for comparison purposes?

Please forgive me if I'm obsessing a bit... just left a 13-year comfort zone with a 3.2 in the back, just don't want to fall prey to any idiot/newbie destructive mistakes (e.g., not keeping oil level at or below 1/2 on dipstick) with the 993 mill before I get more familiar with its care and feeding