Fresh Timing belt running rearward on crank

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TStark
Posts: 127
Joined: Thu Sep 26, 2013 10:24 am
Your car is a: 1975 Spider
Location: NE CT

Fresh Timing belt running rearward on crank

Post by TStark »

Another timing belt issue. '75 1800

Quick summary, my new belt is riding too rearward on the crank sprocket.

Yesterday, it got a new belt and tensioner pully. Got it lined up. Inspected, but didn't like where it was running, almost touching the crankcase and hanging over the sprocket a good 3/16" and showing similar shiny metal in the front of the sprocket where it had run prior.
untensioned and moved the belt forward by hand, it walked rearward when running.

Reveresed the belt, same thing occured.

Took the tensioner pully off, and gave its inner race a 180 spin, and reinstalled. the belt is still running rearward, but by 1/8 vs 3/16".
If i pu some pressure on the belt with a ratchet handle, i can walk it forward when running, but then it walks back.

I timed it and gave it a run around the block, without incident, ran very well.

Ran out of time to retry the old belt, or the old tensioner pully.

However please school me on how serious this is now with the belt still runnign 1/8 back missing some of the crank pulley

Should I 180 the belt again to get it in the indicated direction to undo my test, is the belts running direction critcal to its longevity?

My pulleys are all metal. I searched yesterday for similar topics and found some related, but none adressed the sudden change in path, more were about worn nylon pulleys.

much obliged.
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azruss
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Joined: Sun May 30, 2010 12:24 pm
Your car is a: 80 Fiat 2000 FI

Re: Fresh Timing belt running rearward on crank

Post by azruss »

even the metal pulleys can wear. try to locate pulleys with the shoulder. I am running all OEM with one having a front shoulder and another with a rear shoulder. You could also try rebushing the pulleys. If you have the ability you could run a dial indicator on the top of the teeth to see how true they are.
TStark
Posts: 127
Joined: Thu Sep 26, 2013 10:24 am
Your car is a: 1975 Spider
Location: NE CT

Re: Fresh Timing belt running rearward on crank

Post by TStark »

Understand. are running quite true.
What i'm still having trouble wrapping my head around is it being good prior to the new belt an idler, and bad after install. Suggests its somethign i did.

Last night I gave the new idler puller a full flip, with no effect.

Appears the only pulley there with a rear flange is the intake. If i could shim it forward an eight, i think it would do the trick. Exhaust and Aux pulleys are front flange

Given the available space, i think the 1" belt would work, though i see its not recommended with stock pulleys

or If i could put an intake pully on the aux, thus reversing the flange from front to rear, i think that could keep the belt where it belongs as well.
jronon
Posts: 9
Joined: Fri Dec 02, 2011 8:43 pm
Your car is a: 1974 124 Spider

Re: Fresh Timing belt running rearward on crank

Post by jronon »

having exact same problem, 1800cc, new belt, new bearing, metal pulley wheels - the belt is running about 1/8" off the crank pulley, to the rear, and same on exhaust pulley, and as the belt separates from the intake pulley (has a rear guard) it creates a chirping sound. Touch the belt with a well polished socket extension with the smallest pressure and the sound stops. Worked the belt back to the center of all pulley, started up, and it immediately walked back to the off center position.
1974 124 Spider 1800
1973 124 Spider 1608 (project)
1972 124 Spider 1608 (parts)
1975 Ford F250 Highboy
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