For those of you who have built your own alternator bracket, I was curious how you went about it. I'm assuming that quite a high degree of accuracy is required in building the bracket so that there are no ill effects on the belt system in regards to belt/pulley alignment. I have some ideas but I was curious what others have done and what would be the best way.

1) So, how did you go about actually measuring and building your bracket?
2) Did you measure both the spacing from the engine and the tilt of the alternator pulley?
3) How close do you feel these have to be to avoid problems and excessive belt wear?

Thanks!

I just use a 99 Astro alternator. A hardened alternator bolt, 2 spacers, a length of 3/16" x 1" steel bracket to secure the rear and a piece of 1" L channel for the bottom bracket. The Astro alternator will mount directly to the block. Cost about $12 in materials and 30 minutes of work.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, ZZP Intercooler, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

You wouldn't happen to have any pics of your work, thanks.

These are questions that I've been wanting to ask lately. I've found that, by stretching an old serpentine belt tight in between the alternator and balancer, I can set the alternator very close to being on the same plane as everything else (if the alternator is too far from where it should be, the belt will be distorted in between alt and balancer), however I don't know exactly how accurately placed the alternator needs to be.

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My project: 3800 Series III Supercharged + F40 6-speed into an 87 GT. Wish me luck!

quote Originally posted by Fierotregg: You wouldn't happen to have any pics of your work, thanks.

Should be in the archives.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, ZZP Intercooler, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

quote Originally posted by Dennis LaGrua: Should be in the archives.

I think this is what Dennis is talking about: https://www.fiero.nl/forum/F.../HTML/109934.html#p7

Lots of interesting ideas in that thread.

Edit: Dennis, the top tensioner on your accessory belt looks like the original alternator bracket tensioner. Did you leave the smooth pulley in place, or put in a grooved one?

[This message has been edited by raccoons (edited 11-29-2011).]

Thanks for the info

Thanks Dennis. That looks quite nice actually. It seems this is going to be more simple than I was expecting. I don't suppose you happen to know what belt you used offhand?

https://www.fiero.nl/forum/Forum2/HTML/112125.html

I did what Dennis did and it has held up fine. Saved lots of money. Really is simple to do.

Mounting the alternator low if it isnt already, does clean up an engine bay. I saw an older Chevy at a car show and the moved alternator stood out right away as wrong...it was turning the wrong way. I dont know if its true or not, i have nothing to determine it, but owner told me the alternator charges the same no matter which way it turns. It might help if true, to figure out a way to mount and drive the alternator. Maybe one of the auto electric gurus here can step in to clarify that.

quote Originally posted by rogergarrison: Mounting the alternator low if it isnt already, does clean up an engine bay. I saw an older Chevy at a car show and the moved alternator stood out right away as wrong...it was turning the wrong way. I dont know if its true or not, i have nothing to determine it, but owner told me the alternator charges the same no matter which way it turns. It might help if true, to figure out a way to mount and drive the alternator. Maybe one of the auto electric gurus here can step in to clarify that.

Changing the rotational direction of the alt. would require one to run a smooth pully so the outside of the belt wraps around the now-smooth pully... As long as the ribs of the belt are wrapped around the ribbed pully, it will rotate in the proper direction regardless of where it is mounted; only way to get the ribbed pully alt to rotate backwards would be to install it backwards (back side of the alt facing away from the motor)...

Thats what I noticed on the mentioned car. I was like WTF is that about. If I remember right, he mounted it where a power steering pump would have been. It was almost down to the vibration dampner.

[This message has been edited by rogergarrison (edited 12-01-2011).]

quote Originally posted by GraterFang: Thanks Dennis. That looks quite nice actually. It seems this is going to be more simple than I was expecting. I don't suppose you happen to know what belt you used offhand?

My low mount scheme may be the simplest,cheapest and perhaps the strongest solution but it does require using the 99 Astrovan unit (4.3L engine) not the GTP alternator. The belt that was used for the alternator was a Goodyear Gatorback 4060795. It is 79.5" long and fits my swap application perfectly. Depending on which alternator you use and how you position the tensioner will determine if this belt fits or not.The tensioner on the install that you saw was a cut/rewelded GTP tensioner with the arm tension repositioned by taking the unit apart and drilling a new hole about 60* to the right that retains the armtension spring.When I resassembled the tenioner I drilled and tapped a hole in the center of the tensioner shaft and used a bolt (with JB Weld on the threads) and a washer to hold the arm in the new position. The pulley was changed to a smooth one. Two years and so far so good.
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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, ZZP Intercooler, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

[This message has been edited by Dennis LaGrua (edited 12-02-2011).]

Well here's my first spin on a low mount alt. I used a 99 Astro alt like Dennis was referring to. I ended up actually welding a bracket together though to reduce the number of pieces and for peace of mind. It's probably overdesigned and far from perfect but it seems to fit well and put the alternator in a good spot. I just need a heat shield for it all and I should be done there.

quote Originally posted by GraterFang: My next concern is solving the dilemma of the tensioner assembly/belt routing. It seems to me that the stock accessory belt tensioner is a press fit assembly and I'm not sure I'm equipped to dissemble, alter, and reassemble it. What have those with low mount alts been doing for tensioners? Are there any other reasonable solutions out there? Search didn't provide much here.

The stock assy belt tensioner used on the 3800 Series 2 and 3 engines is not what I would call "pressed" together. There is a retaining washer you will need to cut off to get the tensioner arm (and internal parts) off. After you perform your modifications to reclock the tensioner arm, you can reassemble it and then install a bolt and washer to hold it all together (you will need to drill and tap a new hole for this bolt). Just be careful when cutting off the retaining washer because there is spring pressure behind it. You must also take care when cutting the retaining washer off so that you do not damage the aluminum or any bushing surface under it.

There are two different designs of assy belt tensioners used on the 3800s. Early (~1998-earlier) and late (~1999-up). The late style is much easier to modify and work with than the earlier style is but I've modified both and either will work. Below is a picture showing the late style bracket/tensioner already modified for the low-mount alternator setup...



-ryan

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OVERKILL IS UNDERRATED

Custom GM OBD1 & OBD2 Tuning | Engine Conversions & more | www.gmtuners.com

[This message has been edited by Darth Fiero (edited 12-15-2011).]

Hmm, my mistake then about it appearing to be a press fit but that's good news. Thank you. I'll give it a closer look today. I'm just concerned about getting the tensioner apart and then having troubles getting it back together because of the spring. I'm sure it'll become more apparent though once its actually apart.

i used the west coast fiero set up . expensive but totally complete and bolt on. really well thought out. comes with idler / bracket . rock solid

quote Originally posted by tomsablon: i used the west coast fiero set up . expensive but totally complete and bolt on. really well thought out. comes with idler / bracket . rock solid

Glad you're happy with it. I've looked at options like that but I just can't justify the expense when its something I can do myself. I don't mind spending my time building what I can and bettering myself while I do it as long as I can eventually put out something I'm happy with.

I know this is kind of old school with all the new ATL brackets out there but this set up has worked great for me and eliminated the ugly dog bone support utilizes the stock fiero ATL that i had rebuilt to 130amp , its basicly a 2.8 mount with a triangulare peice of aluminum which bolts to the block and is welded to the bracket with a side to side tracking support at the bottom to stop the ATL from moveing side to side this was custom by Purple Regian turned out great


i have seen so many set ups with just a bolt and spacers and sure they will work but the constant tugging and pulling of the belt on the ATL will break the bolt , without side to side support your in for disaster, from what i have seen all the newer Atl mounts use the stock 3800 Atl

Not a bad looking setup.

quote Originally posted by RULOOKIN: i have seen so many set ups with just a bolt and spacers and sure they will work but the constant tugging and pulling of the belt on the ATL will break the bolt , without side to side support your in for disaster, from what i have seen all the newer Atl mounts use the stock 3800 Atl

I rather doubt that any even somewhat well designed system with grade 8 bolts is ever going to suffer this problem. Granted, more side to side support is great but I think a setup would have to be very poorly designed to actually have the bolts completely break.

I'm certainly not worried about mine breaking.

[This message has been edited by GraterFang (edited 12-15-2011).]

quote I have seen so many set ups with just a bolt and spacers and sure they will work but the constant tugging and pulling of the belt on the ATL will break the bolt , without side to side support your in for disaster, from what i have seen all the newer Atl mounts use the stock 3800 Atl

The 99 Astro alternator that I use mounts dirrectly to the block with rear and front auxiliary brackets. . The bolt holding the alternator "ear" to the block is a hardened alternator bolt that is designed for strength. Installed 2 1/2 years ago and its still holding strong. Since there is a total of three mounting points, I do not expect failure anytime soon. There are other ways to mount the alternator but this one has proven itself.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "