As some of you may know, I'm building a 60-degree V6 for my Fiero. After reading all the comments about squealing alternator belts, I decided to tackle that problem while the engine was still on the engine stand, instead of trying to kludge something together later.

I specifically wanted a belt tensioner, not just an idler pulley. But I couldn't find anyone who sells such a thing. So I built my own. I used a belt tensioner from a FWD 60-degree V6 (I forget what car), and a Dayco 46" belt. See photo below.



The tensioner I used has no built-in bracketry, just one mounting bolt and a retaining tab to keep the base from turning. That made it pretty easy to design a mounting bracket. I originally wanted to use 1/8" steel, but none of the local hardware stores had that in the necessary width. So I had to settle for 1/8 x 2" aluminum stock. I bent it into a question-mark shape, using a propane torch and a big vise. My bracket uses the same 2 mounting bolts as the lower engine mount bracket.

In the photos below, you can see the hole for the tensioner's mounting bolt, and the smaller hole for the mounting tab. Also notice how I shaved material off the side for clearance.







Thanks to the adjustablility of the alternator, and the flexibility of the tensioner, this setup should accept a wide range of belt lengths. Judging by my tests using speaker wire, this setup should accept anything from 45.5" to 47.5". I decided to play it safe with the 46" belt. Here are some shots of the tensioner and belt installed.







In that last photo, look at how close the idler pulley is to the alternator bracket. There's only about 1/16" of space! But the clearance has to be close, because the belt rides so close to the bracket. I just hope it doesn't scrape!

[This message has been edited by Blacktree (edited 06-07-2006).]

Also, here's a technical drawing of the bracket I made, in case someone else wants to build one.

LINK

hmmm, I guess you never saw the one that Rpdney Dickman has for sale on his site then?
a few folks here have them.

http://www.rodneydickman.com/IdlerPulleyKit.html

Yep, here's mine:

quote Originally posted by tjm4fun: hmmm, I guess you never saw the one that Rpdney Dickman has for sale on his site then? a few folks here have them. http://www.rodneydickman.com/IdlerPulleyKit.html

quote Originally posted by tjm4fun: hmmm, I guess you never saw the one that Rpdney Dickman has for sale on his site then? a few folks here have them. http://www.rodneydickman.com/IdlerPulleyKit.html

I guess you didn't read his post....

quote Originally posted by Blacktree: I specifically wanted a belt tensioner, not just an idler pulley. But I couldn't find anyone who sells such a thing.

Now that is really cool! Never have to tighten your belt again, EVER!

I may have to do this one myself...

quote squisher86SE said: Never have to tighten your belt again, EVER!

BINGO!!!

Nice write-up.

Can you come up with a make/part# for the tensioner or
the car it was meant for?

Thanks,

Bob

quote Originally posted by squisher86SE: Now that is really cool! Never have to tighten your belt again, EVER! I may have to do this one myself...

ooops, I misread the initial post.
personally, I hate tensioners. you may not have to tighten it again, but you will be replacing it about 4x as often. I would rather have an adjustable idler than a spring. I only say that cause on my firends last envoy with a v6 and tensioner, he was replacing the belt more than 1x a year, and it was being done by the dealer under warranty. he newer one has an adjustable idler, same motor, and now 2 years old with no belt issues. beats me why they just didn;t leave it all regular V belts.

quote Originally posted by Blacktree:

Does the belt tensioner actually function as a tensioner in this location? Can you move the tensioner enough to release tension on the belt to change it? It doesn't look like it would have the range of motion to actually function in this position.

Very good idea, though. I just added Rodney's idler a few weeks ago, but I do like the idea of an automatic tensioner.

Looks like getting the timing light to shine on the timing marks is going to be a bit of a problem with this setup...

quote Formula88 said: Does the belt tensioner actually function as a tensioner in this location? Can you move the tensioner enough to release tension on the belt to change it?

YES to both questions. In that photo, the tensioner is actually in the middle of its range of motion.

Also, keep in mind that if I couldn't move the tensioner enough to remove the belt, I wouldn't have been able to install it in the first place! The trick is to slip it on/off the water pump pulley.

I also have a clear view of the timing marks. Check it out:



What's with all the cynicism? And what does a GMC Envoy have to do with a Fiero, anyway? Sheesh...

quote Originally posted by Blacktree: What's with all the cynicism?

It's not cynicism. Engineers do this for a living. It's always easier ... and far better ... to ask challenging questions early in the design and implementation process, before you have have thousands of units in the field that are starting to fail because some small detail was overlooked.

Congratulations on what appears to be another good solution to the Fiero V6 belt problems. The only thing I would add is that it is very important that your bracket be made carefully to ensure that the tensioner mounting surface is exactly parallel to the plane of the belt path. If the mounting surface (and thus the tensioner itself) is only slightly skewed it will wear out belts in a hurry.

I, too, would appreciate knowing what GM model (or models) use that particular tensioner.

[This message has been edited by Marvin McInnis (edited 06-20-2006).]

quote Originally posted by tjm4fun: ooops, I misread the initial post. personally, I hate tensioners. you may not have to tighten it again, but you will be replacing it about 4x as often. I would rather have an adjustable idler than a spring. I only say that cause on my firends last envoy with a v6 and tensioner, he was replacing the belt more than 1x a year, and it was being done by the dealer under warranty. he newer one has an adjustable idler, same motor, and now 2 years old with no belt issues. beats me why they just didn;t leave it all regular V belts.

I had a 96 lumina (3.1L) with the tensioner, I only changed the belt once over the 4 years that I had it, and that was right when I bought it as preventive maintenance. You could hardly tell that it had any wear on it even when I traded it off...

[This message has been edited by squisher86SE (edited 06-20-2006).]

Excellent job.

Thanks for the write-up.

I was thinking of adapting the manually adjustable belt tensioner from my daughter's '86 Mazda RX7 but this is better.

Carroll

quote Originally posted by squisher86SE: I had a 96 lumina (3.1L) with the tensioner, I only changed the belt once over the 4 years that I had it, and that was right when I bought it as preventive maintenance. You could hardly tell that it had any wear on it even when I traded it off...

I agree; I never had any unusual belt wear on my Beretta over the 300,000+ miles I put on it. I eventually replaced it every so often when I was bored and looking for new projects.

On the other hand, I have Rodney's idler pulley on my Fiero, and the belt is wearing fast enough to leave a film of pulverized rubber dust on the bracket, water pump, and strut tower, after only a few hundred miles. I'm suspecting an alignment issue, however, but haven't located it yet.

To OldBob and Marvin McInnis: the tensioner came from an early 1990s midsize GM (W-Body?), with a 3.1 V6. I don't remember exactly which make/model it was, though. If you want, I can take some measurements from the tensioner.

[This message has been edited by Blacktree (edited 06-20-2006).]

Assuming the tensioner was also a Dayco - they don't have many to pick from! (you know, in comparison to SOME parts where there's 10,000 varieties of a part)

If you can get ahold of the Dayco catalog, it has pictures, dimensions, etc.
I've flipped through it looking for idlers, etc before when doing swaps.
Should be pretty easy to find.

(of course, an actual part number would be great! )

Looks just like the ones on the early to mid 90's Grand Prix's.

Here ya go: LINK

Nice job and thanks for the info. I've had a bunch of cars with tensioners with no problems, so I would not worry about that. Just keep an eye on it and youll be fine.

quote Originally posted by tjm4fun: ooops, I misread the initial post. personally, I hate tensioners. you may not have to tighten it again, but you will be replacing it about 4x as often. I would rather have an adjustable idler than a spring. I only say that cause on my firends last envoy with a v6 and tensioner, he was replacing the belt more than 1x a year, and it was being done by the dealer under warranty. he newer one has an adjustable idler, same motor, and now 2 years old with no belt issues. beats me why they just didn;t leave it all regular V belts.

If the belt is being replaced that often because it is worn, there is an alignment issue. All my other newer vehicles that have a tensioner on them maybe get a new belt every few years - and this is mainly due to them developing cracks in them. On a side note, I rather replace the belt than the alternator because the bearing is no good from all the stress on it from trying to keep the belt tight.


Blacktree >> excellent work and thanks for hte info on the bracket and such

quote Originally posted by Blacktree: To OldBob and Marvin McInnis: the tensioner came from an early 1990s midsize GM (W-Body?), with a 3.1 V6. I don't remember exactly which make/model it was, though. If you want, I can take some measurements from the tensioner.

Grand Prix, Lumina (Car), Monte Carlo (through 98 or 99) for examples, probably Buick Skylark also and more I'd imagine. That tensioner looks exactly like the one out of my old Lumina. Wonder why I didn't think of it before...

quote Originally posted by Blacktree: Here ya go: LINK

The Advance Auto Parts web site is too smart for its own good! When I clicked the link above it listed tensioner assemblies for our 1998 Dodge Caravan ... rather than for whatever car you specified.

[This message has been edited by Marvin McInnis (edited 06-21-2006).]

Ah, crap. The car specified is a '91 Chevy Lumina (car) with 3.1 V6. But when I was searching through the PartsAmerica site, every early/mid 1990s GM FWD car with a 3.1 V6 that I tried kept turning up the same part numbers.

There should be LOTS of them in boneyards... which is where I got mine.

[This message has been edited by Blacktree (edited 06-21-2006).]

http://www.partsamerica.com/ProductDetail.aspx?mfrcode=DAY&mfrpartnumber=89 203&parttype=819&ptset=A

Dayco P/N 89203 $41.48 Sure looks like it and the same as the 3.1 on my '93 Cavalier RS SW Fiero parts getter. I was just at the yard getting a fender for it. Have to go back and look at the Cavys again.

------------------
Notchbacks RULE

"Let a man drive a Fiero and he'll own one.
Teach a man to fix a Fiero and he'll own eight....errr...nine."

[This message has been edited by Fierobruiser (edited 06-22-2006).]

OK, here's the link to the technical drawing again, for those who missed it... *ahem*.

LINK

Ooooops...... I saw that link....hehehe. The request was for those 'old guys' out there who might have forgotten they saw it. Yeah that's what I meant ..........Thanks again. Oh...and a + for your extra trouble in reposting the link.

[This message has been edited by Fierobruiser (edited 06-22-2006).]

** UPDATE **

The aluminum mounting bracket failed while I was driving the car yesterday. It cracked in half, along one of the bends. Luckily, I was able to get the car back in service by removing the tensioner and installing a stock belt.

But it's back to the drawing board for the mounting bracket. The next one will definately be beefier than 1/8" thick aluminum.

This is the first time i've seen this thread, otherwise I would have said in June, but that bracket unfortunatly looked too thin to support the load on the tensioner. I am surprised it took so long to happen, I thought it would bend when you installed it.

You seem very mechanically inclined, I am sure you can make one that holds.

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More info at: https://www.fiero.nl/forum/Forum1/HTML/043357.html

quote Originally posted by Blacktree: ** UPDATE ** The aluminum mounting bracket failed while I was driving the car yesterday. It cracked in half, along one of the bends. Luckily, I was able to get the car back in service by removing the tensioner and installing a stock belt. But it's back to the drawing board for the mounting bracket. The next one will definately be beefier than 1/8" thick aluminum.

Great effort, looks like your close to having a nice setup. I think I'd consider steel though instead of aluminum for the bracket for longevity. Lots of vibration.

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RickN
White 88GT 5spd
White 85GT Auto
White 99 F250SD 7.3PSD 6spd

ok, to make amends for my previous "cynacisms" (it was a ref to the belt tensioner on a v6 gm motor, that was all)

there are 2 potential solutions for this:

with your aluminum bracket, box one side of the mounting C area at the bottom, ie weld the one side closed with another piece of aluminum. heat the aluminum slightly while bending it, that is tricky to get the heat right, but aluminum likes to stress fracture at bends.
since welding aluminum is not feasable for most people,
most home centers sell short lengths of steel stock. I've see box and L stock of 1/8 to 3/16th thickness. you could implement your exact bracket with 3 L's and some welds, or duplicate it in straight flatstock. Again, heat the steel, red to cherry red will allow you to get a nice sharp bend and not stress the steel. Ideally you would want 3/16th flat to keep the strength up, and with flatstock, it would be easy for anyone to duplicate.
the welded angles would be stronger, as the corners have a fillet on the inner corner, usually slight, but it still adds tremendous strength to the corner.

I did heat the aluminum while I was bending it. But the bench vise's jaws are textured. So when I bent the aluminum, the vise left score marks on the inside of the bends. I think that was part of the problem. And It didn't help that I was using a weak material to begin with. Oh well, lesson learned.

I posted this because I don't want anyone else to have the same problem if they decide to duplicate the tensioner setup.

This looks like a neat project. Since the tensioner is for a GM V6, is there a bracket from this motor that would fit on ours?

Nope. The tensioner bolts to the timing chain cover on those cars. The FWD V6 uses a different timing chain cover, which also serves as a mounting point for the alternator... which is mounted in a different location from the Fiero. The alternator would interfere with the Fiero's dogbone. Plus, the FWD V6 uses a different water pump... which would require some custom plumbing.

I'd rather make a bracket.

Good thinking and good work. Now you will come up with a perfected one. Good Luck
Don

Why not use steel for the bracket. Cut a couple small pieces of 1/8 steel, drill where it needs to be, and weld the joints together. That should be much beefier than any aluminum of the same thickness.

Actually when I saw the pictures of the aluminum bracket I was already fearing a failure, since I've used aluminum like that for other lighter duty things. I read later down the thread that it failed. Sorry about the failure. If it were me I would just use steel. If you don't have a welder take it to a shop and tell them how to weld it together, be right there standing next to them. It shouldn't be very expensive. I used to do that before I bought my Mig welder.

Good luck.
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Carlos A. Martinez
1988 Formula 5-speed, ZZ4 V8
www.txfieros.com

[This message has been edited by TxFieros (edited 08-08-2006).]