Need some help with trying to get my automatic tensioner working. I am crashing and burning at each attempt.

Bought the dayco 89401 tensioner on ebay and some plate steel from lowe's and cut the plate and drilled the holes for my blower.

After moving the tensioner location on the plate a couple of times, I have it where the belt barely gets on the blower pulley and the tensioner is about 80% open (under tension on the belt). Drove down the block to test it and only hit 8.5 lbs of boost. Stopped in parking lot to open the hood and check it out and the tensioner was locked down in the fully extended position. (starting location of the tensioner was about 3 o'clock and ending position about 5-6 o'clock).

Not sure what I am doing wrong here. I will have to start over with another piece of steel, as I put a lot of holes in this one. Ideas? I can't imagine the belt stretching that much during a run, I only took it up to 5700 rpm.

 

This is the tensioner after it goes full lock downward

 

Did you end up getting this issue figured out? Looks like to me it is locking out because of your clocking position of the tensioner. When it is stretched and goes full lock, the tensioner is just past 90degrees perpendicular to the belt , so the belt tension against the pulley is locking it forward.
Looking to do the same to mine, and want to avoid the same issue.

 

I could have re-positioned the tensioner again, but after doing it too many times, i had too many holes too close together. Would need to start with another piece of steel. After looking at this thread on the mustang forums, some guys over there said the tensioner needs to be on the slack side of the belt and not on the tension side:

http://forums.corral.net/forums/supe...tensioner.html

I didn't get a chance to finish it as I need to pull the motor and check the mains for excessive clearance, so it will be a while before i get back to testing it.

 

I have been looking into another option. A company called Indiana Muscle Car sells a spacer that offsets the "standard" SBC Procharger brackets forward so they don't hit the inner fender wells. They also sell a spacer that pushes the crank pulley forward as well.

Prices don't seem bad. $440 satin finish for the serpentine brackets. Than another $75 for the spacer.

I will be looking into this once I get to this step.

Thought I would pass it along.

 

The top side of your pulleys is the slack side if I'm not mistaken since the crank pulley pulls your s/c pulley over from its bottom side. Isn't yours on the slack side?

 

Got a Indiana Muscle Car bracket on my LS swap. Justin is a great guy to deal with!!

 

What the mustang guys were saying was to use the factory manual tensioner on the top side of the belt, (like in the pic where i have the auto tensioner currently), then put the auto tensioner under neath the belt on the 'slack side' meaning the side with no tensioner on it. they are saying that 2 tensioners give you the adjustability you need to handle belt slip, the auto tensioner just takes over where the manual one can't after the belt stretches.

 

Looks like Dayco 89401 is discontinued. Anyone know what replaced it?

 

Call the dayco tech line, very helpful. They have part numbers not listed on the website also.

 

Napa sold me the replacement piece for the 89401, new part is now 89483.

 

I went through the 100+ Dayco part numbers for tensioners and found (only) 1 that tensions in the clockwise direction and comes with a wide enough pulley for a 12-rib belt.

89435

It is around $115 and swings 72 deg.; enough to make it easy to install the belt and still have plenty of tension travel left. I'm running a 1 inch longer belt in this picture (63") than what the pulley combo calls for because it worked out best for tensioner positioning. This tensioner is actually a bit shorter than the stock idler.

Drill the tensioner out to 7/16", drill and tap the plate 7/16-14, and use a 3 1/2" screw.

 

I've been having problems with the belt "walking" off of the dayco tensioner pulley (89483). I ordered a dayco tensioner pulley (89435) to give that a try. I may have tweaked the 89483 tensioner that I currently have on the car.

 

Whats the difference between these tensioners? Can you post a pic when you get it please?

 

Spifz : just make sure that the tensioner cant travel enough so that the belt hit itself.

Been there.........

 

I have an 89429 new tensioner for sale. I will be posting it in the for sale section. Thought I would mention it here since this is the thread that gave me the idea to buy it. Long story short, the F1 is for sale and an LS3 is going in its place. I bought the tensioner for $75. I will let it go for $50 + shipping.

 

10 rib?

-- Joe

 

Tensioner is good for a 12 rib setup from what I gather. That is what mine was. I still have the 4.25" blower 12 rib pulley (also for sale)