belt size with new s/c pulley

[SaleenGT2001]

do i need to drop the belt size on my car. it had a 3.5 pulley and a 108" belt. i dropped to a 3.4 and kept the same belt.

now i am dropping to a 3.2 pulley but i have no clue what size belt i need. anyone have any info to share on this?

 

[BennyBlown2v]

107 1/8th from NAPA is what I'm running with a 3.12" pulley on my vortech setup... Ran a 107 5/8th from NAPA on my 3.3" pulley, and 108 stock belt with 3.6" pulley.

 

[hobbes80]

I know I resurrecting an ancient thread here, but my serpentine belt just shredded itself, I'm running (I think, need to double check) a 3.3 pulley on my vortech. I'd like to get a belt nicer than what I was using, but I don't know the length and there isn't enough of the belt left to determine.

When you say 107 5/8th, I assume you don't mean 107 5/8 inches, because the stock belt is 93.985" according to NAPA... if you DO mean 107 5/8th inches, I assume the extra length is to reach the S/C pulley...

Any info is greatly helpful, feeling a bit retarded today.

 

[hotmustang331]

Yes the belt is 107 inches long. Just go down there and tell them guys to give you a gatorback or gates belt thats 107 5/8s long...6 rib. Napa carries GATES belts...not sure which is better, people aregue all the time which is better. Personally I think I would go with Gates.

 

[hobbes80]

Thanks.... NAPA is telling me they don't make a 107 5/8, they have 1/8 and 7/8.... calling a few other replaces turned up similar results.... I'm going to pick up a 7/8s and if it slips I'll take it back and get a 1/8 and see if it will squeeze on there.

 

[hobbes80]

last stupid question, Is there an easy way to get to the tensioner arm without removing the SC? The bottom of the mounting bracket is in the way and I can't get to the arm

EDIT: I can get to the arm, but I can't get anything into the square hole on the pulley end of the tensioner. I can get it to move by bracing a flat-ended screwdriver against the bottom of the tensioner and the flat-end against the pulley, but I don't want to damage the pulley or the tensioner arm this way...

 

[SilverBullet00]

Im pretty sure you have to remove the bracket to get the belt routed around the two idler pullies. And if there is an easy way after that, id love to hear it as well!

The manual says to lock the tensioner in place with vice grips, mount the supercharger with the belt installed, and then release the vice grips. I have no idea what the crap they are talking about.

 

[hobbes80]

After about 2 hours of frustration trying to route the belt, I undid the mounting bracket for the super-charger, removed the discharge to intake pipe, removed the powerpipe and now the only thing keeping me from removing the S/C is the oil lines, which I'm not ready to empty the case of oil just to change out a belt.

SO, I decided to shelve the project until my roommate can help so he can hold back the S/C while I feed the belt, or vice-versa.

Fortunately, I don't drive it much in the winter anyways.

 

[SilverBullet00]

I feel your pain. I am scarred to death of breaking a belt on the highway now...

 

[SaleenGT2001]

i have a belt changing kit in my car at all times. any s/c car should always have an extra belt and all the tools to change it out.

 

[hobbes80]

OK. After the holidays I finally got a chance to go out into the garage and get back to work on this. I know it seems like I've been neglecting the car... and I kind of have... the 70* day earlier this week just mushed it in my face.

I ended up taking off the S/C (all but the oil lines), routing the belt, using a regular belt breaker to hold back the tensioner. When I put the S/C back on, I wedged a screwdriver under the waterpump and through the tensioner to hold it back. I got everything on the belt EXCEPT for the water pump. I'm using a flat-head to pull back the tensioner, but I can't get it back far enough to get the belt onto the pulley.

I'm so close.

Anyone have any tricks? Would love to take her out today...

 

[hotmustang331]

Can you grind the stop on the tensioner back so you can pull it back further? Or is it just lack of room stopping you?

 

[the98stang]

I just swapped my pulley last night.....what a B1TCH!!! I didn't think the bracket had to be removed to replace the belt....I was wrong. And the old pulley was stuck on there so good, we had to heat the SOB up with a propane torch for 5 minutes before it broke free from the blower. I'm running a 107 1/8th belt from NAPA with a 2.87 pulley.

 

[04YELLOWGT]

Thats one downfall with the Vortechs, they are a bitch to put belts on. I think Prochargers and Novis are easier.

 

[hobbes80]

Can you grind the stop on the tensioner back so you can pull it back further? Or is it just lack of room stopping you?

Not hitting the stop. Can't get the tensioner that far because of lack of room/leverage. The only thing I can get in there at the moment is a flat-head screwdriver, since the mounting bracket is in the way, and that lets me get it back just far enough to tease me.

It is almost annoying enough to make me say forget it and just go buy a roots blower. :LOL: it would suddenly become the most expensive belt replacement ever.

Seriously though. My Roommate is going to help me tomorrow, between the two of us we may be able to get enough leverage/muscle to get the belt on.

Vortech, by the way, was no help on the phone. They just read back the instructions which make no sense. "Use locking pliers to release the tension on the belt"... WTF does that mean?! ... I actually thought about using them to grip the tensioner to the water pump pulley :LOL:... but I didn't want to damage either the pump puller or the tensioner.

EDIT:
OK. Between my roommate and I we got it on. We used my 1/2" drive breaker socket wrench with a 3/8" converter and a 2" extension to get into the tensioner. We pulled the tensioner back out of the way of everything with one bolt holding the S/C for pivoting. Once the belt was in place, I put the rest of the bolts into the mounting bracket. We used a Flat-Head screwdriver to keep the tension off while we pulled the extension and ratchet out. Then we slid out the Flat-head screwdriver and let the tensioner take on the tension. The belt isn't stupid tight, has some bounce in it, and everything is now running.

There is a small knocking sound coming from the vicinity of the tensioner pulley and S/C idler pulley. I'm thinking that in my gusto to try and pull back the tensioner, I may have damaged the tensioner pulley. The knock speeds up and slows down with the engine. I have re-tightened all the bolts on the S/C mounting bracket and am going to live with the knock for the time being, at least it is drive able.

Thanks guys for the help. I need to come up with a mod to do the next time I have to take this thing off so at least I feel like I'm getting something for all my pain and suffering. Maybe I'll go down another size pulley on the S/C...

 

[TonyG]

Strange.

It takes me about than 10 minutes to change a blower pulley on my S-Trim. I do it all the time, b/c I use a smaller pulley at the track than I do everyday.

Changing a belt takes about the same amount of time. I do have to remove one brace between the Vortech bracket and the alternator, but I don't need to remove or loosen the blower from the timing cover.

Regarding changing belt sizes for smaller pullies:

The difference in belt sizes will go like the difference in pulley circumference times the fractional amount of belt wrap around the pulley. In my set-up, the serpentine belt wraps around 80% of the pulley. So,

Difference in belt size = 3.14 x (Diameter1 - Diameter 2) x 0.8

For example, if I go from a 3.2" pulley to a 2.8" pulley, my new belt would have to be 3.14 x (0.4") x 0.8 = 1" shorter than the previous belt, in order to keep the same tension.

 

[BennyBlown2v]

The easiest way I've found in getting the belt on in the garage is just get under the car and push on the tensioner with a long stick (wood dowel, broom handle, w/e you got around) and lever it till it hits the stop, then hold it there with one arm and slip the belt around the ac or power steering - or better yet if you have a buddy helping have them slip it over the alt or water pump. I do what TonyG does and just remove the spacer by the alternator and slip the belt back through there.

 

[hobbes80]

Changing a belt takes about the same amount of time. I do have to remove one brace between the Vortech bracket and the alternator, but I don't need to remove or loosen the blower from the timing cover.

How do you get the belt around the ribbed idler above the A/C with the S/C in place? I can see how taking the S/C pulley off, and the bracket between the blower and the alternator would make getting it fed down to the A/C, past the tensioner. But that ribbed idler is attached to the engine, and there is no space in between it and the bracket to get a belt through.

Either I'm the biggest wuss on the planet or you guys are amazingly strong, but neither myself, nor my roommate could push the tensioner without some kind of leverage, much less hold it with one arm and move the belt around.

I bow to your mechanical skills.


Thanks a bunch for the pulley sizing info. I will definitely be searching for this thread when I change out the pulley.