need some belt help
- Thread starter 1bad67sbf
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So you calculated you needed 73" and got a 73" belt and it was too short.
Hmm, sounds like your calculation is off.
How did you calculate the length?
I always recommend using a length of string routed the same way the belt would go around the pulleys to get close to the size you need. Measure the string after you wrapped it around the pulleys and get a couple belts within 5mms of each other so you don't have to keep running back to the store.
Hmm, sounds like your calculation is off.
How did you calculate the length?
I always recommend using a length of string routed the same way the belt would go around the pulleys to get close to the size you need. Measure the string after you wrapped it around the pulleys and get a couple belts within 5mms of each other so you don't have to keep running back to the store.
giddyup306
Founding Member
- Oct 22, 2002
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I used to do this when people were too cheap to fix things like air compressors... I measured it with a string just like you do. Then I go to the parts store and get three belts. One of the exact measurement, and one bigger, the other smaller. Then I take two of them back. Once you know the width of the belt you can look up the same style on the first part of the part number. The end is the length in millimeters.
different belts from different companies will vary in size. The last time i measured for a belt i used a piece of nylon line from a weed trimmer spool and got the measurement on the money the first time. I think this may work better than the string because there is no stretch to it. Also, keep the line on the same rib when you are running it on the pulleys. This will get you a consistnet size.
Then use a credit card and buy like 5 belts. Thats how i usually do it, 99% of the time you are off by a belt size or two. I get the belt i think it is, then 2 sizes smaller, 2 sizes bigger
Then use a credit card and buy like 5 belts. Thats how i usually do it, 99% of the time you are off by a belt size or two. I get the belt i think it is, then 2 sizes smaller, 2 sizes bigger
tims 86
Member
took me three trips to get the correct one.. tried the string method, didnt work for me. i think i ended up with a 68.5
yeah i started with the string but it did not work because i got a 68in belt and it was way to short. i got the 73 from this graph but it was to short and a 73 1/4 was to long so i thought is someone had this setup they may know what the part number was
giddyup306
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- Oct 22, 2002
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I don't know what you're doing wrong, but there is no way that a 73" can be too short and a 73.25" be too long. Your tensioner will move several inches.
Make sure you are routing the belt correctly. Use the diagrams that you posted if you need to.
i feel the same way but the 73.25 slightly touches itself at the tensioner. i asked the parts store guy how the hell could a 1/4 in change go from too big to too small and his answer was to try to get a part number and try that. the 73 was a double side 6 groove belt but it did say 73 in. i dont know i just want a damn belt on the motor.lol
giddyup306
Founding Member
- Oct 22, 2002
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Then take a picture, and maybe we can see what is going on. Also did you physically measure the belt? There is a chance that it might have been mislabled or mispackaged.
giddyup306
Founding Member
- Oct 22, 2002
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yeah i started with the string but it did not work because i got a 68in belt and it was way to short. i got the 73 from this graph but it was to short and a 73 1/4 was to long so i thought is someone had this setup they may know what the part number was
I don't like the bottom left picture here because it doesn't give much wiggle room for the belt and tensioner to not rub on each other.
I am using the top right method with bypassed smog and ford racing delete. Even though it says in the photo the belt wraps around the a/c pump, it works because the ford racing delete puts the p/s up in the same spot.
This method gives you plenty of room under the tensoner so it doesn't hit, and allows more belt sizes to fit.
No idea what I'm running though as I have custom size pulleys and its been years since I put this belt on.
IMHO...do not use the bottom left method
If you do a search for threads i have made, i made one talking about how basically you can gain or lose as much as an inch in belt length just by loosening the power steering and alternator bolts and wiggling the brackets around. There is enough play in those bolts holes to allow a lot of variance in belt length. If you're almost there with a certain belt length, loosen everything up and see if you can pop the belt on, then tighten everything down. By the time you need to take the belt off again, it will have stretched enough to allow it to go on easy the next time.
Trust me on this, been there and done it 100s of times...it's quite frustrating but this one detail made all the difference in the world.
Trust me on this, been there and done it 100s of times...it's quite frustrating but this one detail made all the difference in the world.
tims 86
Member
i used the bottom left one with no problem,, just a really short belt and the underdrives make it shorter. 68.5
mustanglx91
Member
I always have a set up like the bottom left. Think I used a 76.5 belt with stock pullies with no issues.
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