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Chev alternator brackets - low mount

Started by LXCHEV , Apr 16 2006 08:26 PM

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5 replies to this topic

#1 LXCHEV

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Name:Brett
Location:Melbourne
Car:'76 LX - 383 Chev
Joined: 08-November 05

Posted 16 April 2006 - 08:26 PM

G'day all,

Some questions for anyone with a small-block Chev V8 running a low-mount alternator. I've been having some real drama's with mine. Originally I bought a Redline low-mount kit. Worked fine for a while, then I broke the rear bracket. Welded that as a quick fix. A fair while later I then snapped the lower bolt clean in half (snapped off flush with the block). Replaced it, ok again for a while. Today at Easternats I snapped another bolt (the same lower one). It's driving me crazy. I have replaced the whole kit with another Redline one, it's nearly the same however this one is slightly different, as I now need to use spacers/washers to make up the gap when bolting up the alternator.

I am running a gilmer belt drive on mine, but don't have the belt tight, just medium tension. There is a big vibration when the car is running. If I put my hand on the alternator the vibration is rough as. If I run the engine with the belt removed the vibration goes away. No, it's not the alternator itself, I have tried 2 brand new alternators. I did recently replace the gilmer belt (but nothing else), and this vibration has developed ever since. It's the correct belt, I was hoping it just needed to bed in or something, but it's not.

So what I would like feedback on is:

* What brand of low-mount kit do you guys use?
* Does your alternator fit straight in without adding spacers/washers?
* Are you running standard fan belt or gilmer belt?
* Had any drama's with anything? etc etc......

I just don't get why replacing the belt has introduced such a harsh vibration. And also why I have now snapped 2 bolts and 1 bracket in the last couple of years. It's just an alternator, it should be simple!!!!!

Any comments would be appreciated! PS. I think I'm going to get rid of the gilmer belt setup and go back to standard pulleys...

Cheers
Brett :furious:

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#2 _CHOPPER_

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Posted 16 April 2006 - 09:02 PM

The rear bolt breakage, you're not overtighening a too long bolt into a blind hole, are you? The alternator vibration indicates a possible mis alignment. The fact you used washers as spacers tends to back this up, as washer thickness isn't always consistant. It's possiblr there is a fault with the belt. I've heard of instances where a visibly perfectly belt is fine in the packaging. Place it under load and they start jumping all over the place and creating harmonics. It sounds as if there is more than one problem with your setup.

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#3 racean69

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Name:Rod
Location:Central QLD
Car:LH sedan
Joined: 07-November 05

Posted 16 April 2006 - 09:58 PM

Brett,
The vibration is not from your water pump is it? Try the screwdriver to you ear trick. CAREFULLY!!

It's possible that from welding up your old bracket it has cause some shrinkage in this area and possibly a small amount of missalignment resulting in your broken bolt.

Other wise could the new belt be a slightly different pitch. Do you still have the old belt?

Maybe the pulleys are worn slightly. I know with roller chain type drives ,motor bikes etc the whole lot should be replaced as a unit.

Regards Rod.

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#4 _SSHatch_

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Posted 18 April 2006 - 10:18 PM

Bolts breaking off are a common issue with these setups.
I replaced both mine with cheap ass bolts from the Hardware store.
Softer steel and allow a certain amout of flex.
Dont go the high tensile bolts as the tensile strength is great but their shear strength is stuff all.

As fo the harmonics and stuff, if it only started after you replaced the belt then thats a pretty good place to start looking.

Try a new one, surely you kept your receipt and bought it from a respectible store that will allow you to try a new one due to that one being faulty!!

Edited by SSHatch, 18 April 2006 - 10:21 PM.

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#5 _chief_

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Posted 19 April 2006 - 06:12 PM

Brett, I have the same issues and put a thread up on it in general questions. Heres what I wrote:
Has anyone found a low mount chev alternator bracket that is doesnt flex????
I had a gilmer belt on my chev which ended up snaping the top bolt in the block. Got the bolt out, replaced with grade 8 bolts got rid of gilmer belt and went back to v belt. Snapped top bolt again, had to heli-coil this time.
Purchased new alternator and bracket from rocket ind. which was heaps stronger looking but wont stop the flex in the bracket which inturn pulls the far side of the alternator around making the belt not run true. Anyone own a chev and have had the same problem and fixed it????

Actually after the first time I fixed it, I still had the gilmer, went to the drags a few times, heaps of street K's and then went in the nats burnout comp and snapped it in the block, didnt have the tools to get it out so I had to be a spectator.
The next time I snapped it was at the nats again, with a V-belt, even though I replaced both bolts before I went down. I dont think they like been revved on and off but I know it is pissing me off too.
Some one in the thread I put up had one that was fully welded and had a brace back to the engine mount bolt. This sounds like the go. Im thinking about talking to my mate who works in an engineering shop and seeing if we can make one up.

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#6 Tiny

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Name:Tiny
Location:Sydney
Joined: 04-February 07

Posted 19 April 2006 - 07:50 PM

Thats really weird guys... Ive seen this happen, but not experienced it yet! ( Touches wood!!)

I'm running a V belt with alloy pulleys, Altenator and short water pump, and ive had to space the alternator bracket to fit.
The bracket i use is similar to the redline one, but its a speco brand one i think? Its that old it came with the car!! I'm pretty sure its running Grade 5 bolts ( again the bolts that came with the car!)...

Personally... i hate Gilmer setups.. Ive got my V belt tensioned fairly light, but dont have any problems with it.. the belt runs 110% true no matter what revs ive found. Never spit a belt off never broken a belt No hassles!

I dont know of any stronger or different brackets cause ive never needed to research them!
Sorry i cant be of more help! What a headache!

Cheers!