Altenator adjustment bolt? (Page 1/1)
fierogt28 AUG 09, 12:21 AM
Does anyone know that the alt adjustment bolt has a star washer to keep it from moving on the adjustment slot bracket?

I have the GM part number for the bolt, might check GM dealer to see if its still available...

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fierogt28

88 GT, Loaded, 5-speed.
88 GT, 5-speed. Beechwood interior, All original.

theogre AUG 09, 09:05 PM
Not usually.
Long bolt w/ nut is often a "Flange Face" nut w/ "locking" feature too. (Not same as smooth flange face.)
Short bolt has similar head on it.

If can't find the nut, use a Nylock nut w/ plane washer.

Also try bolt isle in auto parts stores. Dorman has a lot of car hardware sold thru them.
Try Tractor Supply too.
HD Lowes etc have right thread but not right head or nut types needed here.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

fierogt28 AUG 09, 10:08 PM
Ogre, there is no nut...its just a bolt with a star gripping washer to prevent it from moving on the head end against the flange.

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fierogt28

88 GT, Loaded, 5-speed.
88 GT, 5-speed. Beechwood interior, All original.

theogre AUG 09, 11:26 PM
so it's the short bolt goes into the alt?

Don't think the washer is OE. Not sure.
Star lockers can eat the slot over time. More so on V6 w/ aluminum mounting bracket.

Many tighten the short bolt and never tighten the big bolt. All belt load is on the short bolt and that load can move the alt making the belt lose.
Proper torque of the Big bolt clamp the bracket into the alt and takes a lot of belt loading.

If you "grease" the short and/or big bolt for anti rust etc...
Keep all lube and anti seize off the areas where alt and bracket meets. Any lube there and you never keep a belt tight.
Any thread lube then throw out torque tables too... Most values are Clean Dry hardware only.
pmbrunelle AUG 10, 01:12 AM
I have an M8 bolt with a large captive flat washer for my alternator adjustment.
It's the style that's commonly used on the Fiero body.



The bolt is threaded into the alternator housing, so there's no nut. If your alternator housing's thread is stripped, it can be repaired with a Heli-Coil (as I did to mine).



I don't know what Fieros had stock, but this setup worked for me. I didn't have issues with the alternator losing its adjustment.

If you're looking for the Concours-restoration answer, I'm not the guy for that.

My Fiero has the SI alternator; yours will look a bit different having the CS alternator.

I agree with Ogre, I wouldn't want to use anything with star points; that would chew up the aluminium. I have the large captive flat washer expressly for the reason of avoiding damage to the aluminium bracket.
Patrick AUG 10, 01:35 AM

On one of my Fieros (I forget whether it had a 2.5 or 2.8), instead of the adjustment bolt screwing into the soft aluminum threads of the alternator housing, I used a longer bolt coming through from the backside of the housing. It was snugged up tight in the aluminum housing, and then a regular washer and nut was put on where normally the head of the factory installed bolt would have been. With a wrench holding the already snugged up bolt in place, the nut was tightened as much as I freakin' wanted it ... as I no longer had to worry about stripping those soft aluminum threads in the alternator housing. Worked great, never slipped after that.
theogre AUG 10, 01:42 AM
Ouch, You can see damage done by the old, likely OE, bolt even then.
Wrong bolt, OE or otherwise, is likely a big reason why so many V6 alt brackets break there or at end(s) of slot as the bolt makes the slot to spread out.

I've seen enough steel alt brackets bend or break too on other cars. Some have wrong bolt to start with, Others lost the OE bolt and stuff any crap in there. Worse they often way over torque them too w/ oil etc on treads.