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Alternator to water pump belt top side looks like a long, unsupported run (bracket holds the alternator out pretty far it seems). Could flap and twist with a lot of harmonics in that length. Could you put an idler in there to just give it a bump out of being a straight shot?
Also, a 175 amp alternator rotor will have a lot of mass, which acts on the belt at a shift. Can you try a de-coupler type pulley? They were developed for fast shifting transmissions to keep belts from squeaking on WOT shifts.
Alternator to water pump belt top side looks like a long, unsupported run (bracket holds the alternator out pretty far it seems). Could flap and twist with a lot of harmonics in that length. Could you put an idler in there to just give it a bump out of being a straight shot?
Also, a 175 amp alternator rotor will have a lot of mass, which acts on the belt at a shift. Can you try a de-coupler type pulley? They were developed for fast shifting transmissions to keep belts from squeaking on WOT shifts.
That was my thought as well because usually there's a water pump pulley there to shorten it up right?
I'm adding an idler pulley to the spot circled below since that hole is not in use and almost at the halfway point.
The tensioner pulley will make contact with it without a belt on but with a belt it will have plenty of room so I'm not too worried about it.
It will also take some slack out of the belt which should help, I'll check the alignment once the tools show up next week.
The De-Coupler Pulley looks very cool, a bit pricey but if the idler doesn't help and the alignment is good then this is something I'll have to explore further.
Do you know off hand if they make one for LS alternators?
Well gents the pulley and the alignment kit showed up today.
The Dayco kit is a nice piece btw, sturdy and easy to use.
Slapped it on the crank pulley and alternator pulley and wouldn't you know it, the alignment is dead nuts on.
So its gotta be the long distance between the alt and crank, I added the idler, checked the alignment on the idler for good measure, the tensioner is almost completely maxed out but I can get the belt off and on.
Then I saw the tensioner pulley and for some reason the belt is off just a hair, no idea why, there's no play in the arm or the pulley.
Shoot me in the face.
What do you guys think?
The gates rpm belts don’t stretch , period. I would try one . They are Kevlar , made for blower cars . I run one on my Whipple after going thru a million belts .
The gates rpm belts don’t stretch , period. I would try one . They are Kevlar , made for blower cars . I run one on my Whipple after going thru a million belts .
Gates also makes a lot of timing belts and motorcycle final drive belts. If a Gates belt is not working, you have some other problem. The only thing that I know of that will commonly cause them to fail is EXTREMELY excessive heat. This can turn them to dust in 1/10th of their rated lifespan.
I can see from your picture in post #24 that the belt is not centered on tensioner and actually running off the edge. Pulley is either off centerline, or tilted causing the belt to "walk downhill" off the front of the pulley. Belts can usually handle up to 1/3° misalignment fore/aft.
You always want to reserve a certain percentage of tensioner travel in order to avoid bottoming during speed transients. I can't remember the number off top of my head but I think it's in the neighborhood of 25% travel (keep that much in reserve). This is adjusted by belt length.
You also have a rimless tensioner because it's riding the back side of the belt. I'd think that would be a total bitch for throwing belts because that's where most the slack will occur in the belt drive during speed transients. Stock is ribbed and needs extra tall rim to avoid throwing belts with high power engines and quick decel. Your particular application with rimless pulley might truly require a manual tensioner to stop the belt from going too slack. Switching to a manual tensioner would rank #1 on my list if I was in your shoes.
If you install a manual tensioner then adjust tension and run engine for 10 - 15 minutes, and then adjust again. That run time allows the belt to fully sink into the grooves which will effectively make it longer. Things will stabilize and the second round of tensioning should be all you need. Repeat this procedure any time you remove / install the belt.
I can see from your picture in post #24 that the belt is not centered on tensioner and actually running off the edge. Pulley is either off centerline, or tilted causing the belt to "walk downhill" off the front of the pulley. Belts can usually handle up to 1/3° misalignment fore/aft.
You always want to reserve a certain percentage of tensioner travel in order to avoid bottoming during speed transients. I can't remember the number off top of my head but I think it's in the neighborhood of 25% travel (keep that much in reserve). This is adjusted by belt length.
You also have a rimless tensioner because it's riding the back side of the belt. I'd think that would be a total bitch for throwing belts because that's where most the slack will occur in the belt drive during speed transients. Stock is ribbed and needs extra tall rim to avoid throwing belts with high power engines and quick decel. Your particular application with rimless pulley might truly require a manual tensioner to stop the belt from going too slack. Switching to a manual tensioner would rank #1 on my list if I was in your shoes.
If you install a manual tensioner then adjust tension and run engine for 10 - 15 minutes, and then adjust again. That run time allows the belt to fully sink into the grooves which will effectively make it longer. Things will stabilize and the second round of tensioning should be all you need. Repeat this procedure any time you remove / install the belt.
I tend to agree, I'm currently looking for a flanged pulley to help keep the belt in place, looked at other spring loaded tensioners but none will physically fit.
I tried finding a manual tensioner but nothing I've found looks like it will work unfortunately, open to suggestions for sure.
I've got the shortest belt I can install on there so there's plenty of travel in the tensioner.
Gates doesn't make an RPM belt short enough for my application either.
Last edited by Black_Sunshine_99; Jun 19, 2022 at 03:11 PM.
Dayco is a huge manufacturer of belts, I'll bet they make a belt that is shorter. Their part numbering system has the belt length in 'mm' and rib count, so it's really easy to search by part number.
If your belt is too long then it's a similar problem as too short, the tensioner runs out of movement during moments of belt slack during speed transients.
Dayco is a huge manufacturer of belts, I'll bet they make a belt that is shorter. Their part numbering system has the belt length in 'mm' and rib count, so it's really easy to search by part number.
If your belt is too long then it's a similar problem as too short, the tensioner runs out of movement during moments of belt slack during speed transients.
That's what I did, my current belt is 525 mm long and Gates doesn't go down that low unfortunately.
My previous belt was too long I think, it was very close to the end of the tensioners travel.
This newest belt is much tighter, the tensioner can still move in both directions even after adding the idler pulley so I think I have range of motion with it.
Just need to determine whether there is an issue with the tensioner/pulley since the belt wants to walk towards the front just a little, it doesn't come off but it hangs off the edge a little which makes me nervous.
The tensioner pulley does have a little play so I'm going to investigate that this week.
Quick update gents,
Okay so I pulled the idler pulley and the tensioner to get a better look at what was going on.
The Goat Built bracket for the tensioner actually has the ability to clock the tensioner in three different locations so thinking of what @QwkTrip said about travel I re-clocked the tensioner so it wouldn't be so close to the max end of tension, this actually moved it away from the idler as well giving me more room.
The tensioner assembly felt good with no side to side play, not bound up at all, the pulley felt really stiff on the car but once I had it off it spun freely so that was a little odd.
I also added a large washer to the back of the tensioner to move it out away from the bracket in order to center the belt, did the same thing on the idler.
The belt now rides right down the middle of the tensioner and idler, when I rev the engine in park the belt no longer wanders from one side to the other.
The problem was so severe that even a quick hit in first gear short shifting at 5,000 rpm into second would toss the belt.
So next was a couple short hits close to home incase it tossed or ate the belt again, made three hits in first up to 5,500 rpm short shifting into 2nd then quickly into 3rd, pulled over after each to inspect and so far so good.
Supposed to be sunny tomorrow so I'll head out then and make a full hit and report back.
What a pita lol.
Success gents!!!
Went out and made a couple hits yesterday running the shift point out to 7,200 and the belt remained in place which makes me very happy.
Now I can continue WOT tuning and make some head way with this combo turning the boost up.
Thank you very much to everyone who chimed in and help me navigate this irritating issue.
Glad you worked it out. Sometimes the internet is not entirely evil. People on this forum are one of the reasons for that.
I'm very excited, I went out and made another hit yesterday again hitting about 7,200 rpm on the shift (it gets there so fast lol) and feels good looking at my volt gauge and not seeing it stuck down low lol.
Absolutely, I'm a big fan of forums like this one, 99% of the folks wanna help others out, there are a couple dicks but I don't pay them any mind and neither should anyone else.
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