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Discussion Starter #1
If you saw my video I posted a couple of weeks ago showing what's going on with the belt on my YSI, you could see the need for some control on the slack side. After a lot of research, I bought a Dayco 89419 tensioner for a industrial strength diesel truck to see if I could adapt it to my car. It looks like the same one from the video of the COPO Camaro underhood video that circulated a while back.

I tried the existing 56" Dayco Gold Label belt but it would have let the Vortech tensioner pulley contact the Dayco tensioner pulley. I'm pretty sure it has stretched some too. The only shorter heavy duty belt I could find local was a 55" Gates Fleet Runner. Using a 2" x 1/4" piece of 1018 flat bar. I drilled three holes on the center line of the bar. One for the tensioner and two to share existing holes in the manual tensioner to the head unit. I used the hole closest to the supercharger pulley that acts like a pivot for the manual bracket and one of the slotted holes located at 6 o'clock from the pivot bolt.









This setup flat out works. Here is a before and after boost graph. Manual line is readings just from the manual tensioner and new belt taken on 9/30. Auto line is readings from only the addition of the auto tensioner taken on 10/3.



Here is a new video of the automatic tensioner doing work:


I still need to clearance the fan a little more as the tensioner hits it sometimes. Hardest part about this installation is getting the belt on. The 55" belt has to be walked on without any tensioner pulleys in place. Since the auto tensioner is so close to the fan, you can't get a 1/2" drive anything in the square hole to pry it down. I ended up ratchet strapping the pulley down and releasing it & pulling the strap free once I walked the belt on. The manual tensioner has to be pushed down until the belt clears the water pump pulley. Since the square holes are covered by the auto tensioner bracket, you have to carefully pry down on the manual tensioner with a screwdriver.
 

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good job converting. i too converted my d1sc from manual to spring loaded tensioner went from 12lbs to 14 even with a .6 bigger pulley. amazing how much those belts stretch. very happy with mine
 

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Nice work! I ran into a similar issue and had to add a small ribbed idler near the tensioner pulley, but on the inside of the belt. Here's how close it was without it:



Clearly, the belt would touch itself under load.

Here's with the idler:



Maybe this info might help down the road. But again, nice job!
 

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Have seen a few of these setups now. The recent videos and dyno chart give lots of info. I have a box of spring tensioners, should take a look at putting something together. I know one issue I have had on another build was how much the blower moved when adjusting the fixed tensioner pulley.
 

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Discussion Starter #10
I would have to remove it to get a good picture but it's a pretty simple bracket to make and bolt on. See if these pictures make more sense of it. The auto tensioner mounts over the manual tensioner using the holes indicated. The pin that keeps the auto tensioner from rotating catches the edge of the bracket.
 

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Wondering if i could get some tensioner help for my set-up. I have an 89 trans am with a ysi and can only get 12.6 lbs out of it with the 7.8 and 2.95 pullies using the 10-rib belt at 6500 rpm and before manual tensioner, and now serpentine tensioner. I got the same boost with the same pullies using a t-trim, so i think my set-up is slipping. Thing is, when you look at the data logs, the highest boost attained is 12.6 lbs and it doesn't drop off anywhere threw the rpm range like normal slip looks like.

I made my own bracket out of home depot 1/4 steel plate and drilled the holes to hold the serpentine tensioner, then later tried to add an idler on the slack side of the belt. Haven't run this new set-up yet, but just idling the motor has the serpentine pulley riding on 3/4 of the belt, so i think i have an alignment problem somewhere.

Questions:
1. do you agree that i am seeing slip with 2.95 blower, 7.8 crank, 10 rib belt and 64-6500 rpm and only getting 12.6 lbs of boost even though it doesn't 'look like' it is slipping on the logs?
2. how do you bump the belt on? wouldn't that damage the ribs when bumping it on the pullies which would make it potentially slip even more?
3. does the automatic tensioner work better on the slack side of the belt vs replacing the manual tensioner with the automatic tensioner? i guess i should try putting the manual tensioner back on car and adding the auto tensioner on the slack side to see what happens.

1st pic is the old auto tensioner that got me 12.6 lbs
2nd pic is new set up with idler that i haven't tried yet
 

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1. I don't know detailed differences in real world performance to give you a dependable answer.

2. Bumping on the belt - you get the belt on as much as possible, then applying pressure to the belt near a pulley, you bump the starter, with the coil disconnected. It's not horrible for the belt unless you damage it, but it is incredibly stupid to do. Very easy to lose a finger this way. You're better off slotting the mount for an idler pulley or loosening an idler pulley to get enough play to put the belt on (this is what I do with new belts).

3. The automatic tensioner must go on the slack side. It'll do less than a manual would do on the tension side. A manual tensioner on the the tension side and an automatic tensioner on the slack side would give you the ability to fine tune the spring load and probably make the belt easier to put on.
 

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I was trying to follow the new vortech mustang kit's lead in putting an idler pulley on the slack side like in the attached pic.

When i called Vortech to ask questions about where to put the automatic tensioner and if it mattered if it went on the tension or slack side, they acted like they didn't know anything. I am ASSuming that they have done alot of research in putting the idler where they put it, or maybe they just put it where they could fit it, don't know.
 

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Discussion Starter #14
Wondering if i could get some tensioner help for my set-up. I have an 89 trans am with a ysi and can only get 12.6 lbs out of it with the 7.8 and 2.95 pullies using the 10-rib belt at 6500 rpm and before manual tensioner, and now serpentine tensioner. I got the same boost with the same pullies using a t-trim, so i think my set-up is slipping. Thing is, when you look at the data logs, the highest boost attained is 12.6 lbs and it doesn't drop off anywhere threw the rpm range like normal slip looks like.

I made my own bracket out of home depot 1/4 steel plate and drilled the holes to hold the serpentine tensioner, then later tried to add an idler on the slack side of the belt. Haven't run this new set-up yet, but just idling the motor has the serpentine pulley riding on 3/4 of the belt, so i think i have an alignment problem somewhere.

Questions:
1. do you agree that i am seeing slip with 2.95 blower, 7.8 crank, 10 rib belt and 64-6500 rpm and only getting 12.6 lbs of boost even though it doesn't 'look like' it is slipping on the logs?
2. how do you bump the belt on? wouldn't that damage the ribs when bumping it on the pullies which would make it potentially slip even more?
3. does the automatic tensioner work better on the slack side of the belt vs replacing the manual tensioner with the automatic tensioner? i guess i should try putting the manual tensioner back on car and adding the auto tensioner on the slack side to see what happens.

1st pic is the old auto tensioner that got me 12.6 lbs
2nd pic is new set up with idler that i haven't tried yet
1. Don't know enough about your combo to guess if you are having belt slip.
2. I walk the belt on manually. I get it on the blower pulley as far as possible, put some pressure on it with one hand at the pulley, and then turn the motor over by hand. I would never bump it on with the starter. Haven't had any issues with belt damage. Probably sees way more abuse in normal use.
3. Always put the automatic tensioner on the slack side.
 

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you need to get your tensioner more parallel with the belt, in other words the spring side needs to be lower. see how your tensioner is straight down on the belt or over center? it wont work correctly the way it is. i found out the hard way, once the belt stretches when you rev it, it will go over center and not return. does look better with idler.
 

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Discussion Starter #18
bigdumbredneck, how long is your 2" x 1/4 thick bracket? thinking of making the same thing you made tonight
and are all 3 holes the same distance away from each other?
I would have to take the bracket off to measure it. Lay the manual tensioner over the 2" x 1/4" plate and mark two of the holes that exist in the manual bracket. The third hole is placed as close as possible to the middle hole only leaving enough room to access the bolt that will be in the middle hole.
 
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