I'm getting pretty tired of having to re-tighten the alternator belt on my '84 duke every couple of weeks. (The '87-'88 dukes use a serpentine belt and a tensioner.) Any of you who have had the problem of a squealing belt at start-up know what a nuisance and embarrassment this is! It's worse in the rain, and by gawd, it rains here almost constantly this time of year.

On my '86 GT I've installed Dodgerunner's belt tensioner and it works great.

Rodney also sells an idler arm/pulley for the 2.8. This is what it looks like installed.



So, I was wondering if anyone has ever made something similar to Dodgerunner's tensioner or Rodney's idler for the '84-'86 dukes? Just that little bit of extra belt "wrap" around the alternator pulley would probably make a world of difference.

Actually, someone did, and even wrote it up in this forum. I'll try to find it.

When I was having this same problem I found that a PO had installed a Head bolt in place of the pivot bolt for the alternator. This let the alternator cant just enough to wear the belts pretty quickly. I installed a 10MM bolt, (might need to measure it to be sure), in the head bolts place and all was well in 'Duke" land thereafter. The head bolt has a larger shank just underneath the head, but smaller the rest of its length.

Ya might take a good look at that bolt.

quote Originally posted by TopNotch: I couldn't find it -- maybe it was somewhere else. It was a strictly one-off homemade thing.

I had done quite an extensive search of the forums before I posted and couldn't find anything. It would certainly surprise me though if someone hasn't posted about doing something along these lines previously.

quote Originally posted by Patrick: You bring up an excellent point. When the upper bolt is loosened, the alternator actually flops around a bit on the lower pivot bolt. I was suspicious of this and replaced the bolt (and possibly the whole bracket as well, I forget) from an '84 parts car I have. Made no difference, the alternator still flops around (side to side) if the upper bolt is loose (and the bottom bolt is tight). Hmmm... How much play should the alternator have on that bottom pivot bolt?

I am wondering if you have the long hole wallowed out now. Mine had next to no slack or wobble after I installed the new bolt. I think I took the alternator to the hardware store with me to get the largest size bolt that would go in there.

The 'slop' you are describing is what made me look for the reason it was there.

quote Originally posted by TopNotch: I couldn't find it...

I was searching the forums for a Goodyear Gatorback belt part number and found the thread Here.



Nicely made, but a good point was brought up...

quote Originally posted by KurtAKX: As a nerdy engineer, I do have to mention that V-belts are not intended to be bent "backwards" and the increased strain and tension in the fibers at the bottom "tip" of the V will cause a shorter belt life.

I'd be curious to know whether this did indeed affect belt life at all.

I'd love to build one, I just need to find an early duke engine to work with. I got a duke but it is also an 87 so out of luck there.
Guess if one shows up at the u-pull-it I might have to spring the $ for a motor..

[This message has been edited by Dodgerunner (edited 10-14-2010).]

quote Originally posted by Dodgerunner: I just need to find an early duke engine to work with... Guess if one shows up at the u-pull-it I might have to spring the $ for a motor.

I've got one here you could have for free. Shipping might be a bit much though.

I have the same problem-especially when it's raining.

Now that we're back to monsoon season here, belt slippage and squealing on the duke has gotten worse again.

I'm just wondering if anyone (Dodgerunner?) might've had a brainstorm since this thread last appeared.

the po of my 84 actually stripped out the top alternator bolt on the alternator. I figured this out on the side of the road when the car threw its belt and I had to have it towed home. New alternator fixed this but I don't have the right top bolt for it. The po had some cobbled up crap in there. I found a bolt that fit the alternator but I'm not sure I got it to bit good enough in the slide groove. Guess I will know when I take it for its first spin in a few years. I'm not happy with the tightness of the belt though. I would love to get my hands on a tensioner to take up any access slack.

The tensioner is still working just fine. I don't drive the 84 much anymore but it has around 5 thousand miles on it now.

Email me if you want more pictures or info.

Original post https://www.fiero.nl/forum/A...100421-2-099214.html

Ray

[This message has been edited by rdean (edited 09-24-2011).]

Ray, thanks for chiming in. I've got a general question for you in regards to the tensioner you designed and built.

Had you at any point considered using the type of readily available tensioner (shown below) that Dogerunner uses (with his custom bracket designed for the 2.8), and if so, why did you go the route you did? Was it just a matter of using what you had, or was there something about that style of tensioner that wouldn't work with a custom bracket installed on the duke?

quote Originally posted by Patrick: Ray, thanks for chiming in. I've got a general question for you in regards to the tensioner you designed and built. Had you at any point considered using the type of readily available tensioner (shown below) that Dogerunner uses (with his custom bracket designed for the 2.8), and if so, why did you go the route you did? Was it just a matter of using what you had, or was there something about that style of tensioner that wouldn't work with a custom bracket installed on the duke?

I wonder if the same tensioner could be adapted for a v style pulley?

All the factory belt tensioners I have seen are large with a lot of spring tension. There isn't much room in this area to to mount one but it could be done with some work. The reason they are so large and have such a high tension is because they tighten the belt between driven components on the engine. Lets assume that the tensioner is installed between the water pump and the alternator and so presses down on the belt to keep it tight. With the alternator charging this will tend to raise the tensioner and actually loosen the belt around the alternator pulley. That is why they have such a heavy spring tension built into them to overcome the horse power requirements of the alternator. If the tensioner is placed after the last driven part, which is where the slack of the belt normally would be, then the required tension at that point is greatly reduced. The spring that I used holds only a few pounds of force against the belt to remove the slack and keep the belt wrapped snugly around the alternator pulley. The more horse power the alternator calls for actually causes the belt from the crank shaft pulley around to the alternator to get tighter with the tensioner just taking up the slack.

I also have this same design on my 85 2.8 engine and it is working fine also.

I originally made one for my 86 4.9, and there are pictures of it in my other posts, but it did not work as well and I have removed it and went back to manually adjusting the belt when needed. On the Cad engine the timing cover extends out past the crank shaft pulley in some places. The factory cover has areas indented in the cover for the factory belt setup to run in but if you change the belts angle from the alternator to the crank shaft then the belt will rub on the timing cover. Not good.

I am not saying this is the best solution only this is what has worked for me.

Thanks
Ray

I had to tighten down the pivot bolt on mine to get it to stop squealing and eating belts. I have to loosen both bolts to adjust it now. Did it with the pry bar still holding the alternator in place. The belt is very tight. I do worry about the stress it's putting on the water pump and alternator bearings though.
Oh by the way it has the reduced shank diameter bolt on it also. The one on my GT does too. That one had never been off before so I think that's the factory bolt. I had to tighten the pivot bolt on the GT also to get it to stop squealing.

quote Originally posted by rdean: All the factory belt tensioners I have seen are large with a lot of spring tension. There isn't much room in this area to to mount one but it could be done with some work.

Ray, in your opinion (since you've obviously spent some time scoping this out), would a factory belt tensioner not fit on the duke in roughly the same place that Dodgerunner has located it for his 2.8 application? It would be "easier" to use one of these tensioners IF it would fit as they're readily available and would require less fabrication than what you've created. I love what you've done, I'm just looking for the simplest solution.

I know that Dodgerunner has expressed interest in the past in creating a auto-tensioner/bracket for the '84-'86 duke, but the last I heard he still didn't have one of these engines to use as a guide.

I am sure there is some adjuster out there that could be fitted to the duke but I didn't investigate that route. I just made it as I went along from what I had on hand.

sorry

Ray

Ray, certainly no need to apologize. You did a great job with your tensioner!