electrical and ignition BNR 85A Pulley Diameter

[NullZwei]

I just purchased a BNR 85A alternator to replace a similar alternator that was damaged.  Of course this was before I read the post on the bad BNR bearing issue.  The first thing I noticed was that the drive pulley on the new alternator was smaller in diameter than the one on the alternator it's replacing.  The outside diameter of the pulley on the new alternator is 2 9/16" whereas the outside diameter of the old pulley is 3 1/16".  I'm not absolutely certain it would make that much difference so I'm trying to decide if I should leave well enough alone and go with it as it is or use the old pulley on the new alternator.  If anyone has any thoughts on the matter please chime in.  Thanks

[Rocan]

you can use the stock belt with the longer pulley, but you will be on the limits of adjustment. Using a larger pulley will result in less amperage at lower RPM.  Ask blunt for a v belt thats a tad bit shorter than stock and you will be in business..

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Oh, and good luck.Take note how long the alternator lasts, and flame the hell out of BNR when it fails. 

[JohnS]

I've had good luck with the alternators and starters from BnR.  I guess I've been lucky.  I was a little pissed when I purchased one of their tii alternators and it came with a "too small" pully.  I ended up just swapping the stock pully onto it from my old alternator.  I have too many spare fan belts in my stock of parts, that I'm not changing sizes any time soon.  What pissed me off was they install their small pullys without a key in them, so they spin when you try to hold the pully and undo the nut to do the swap.  I had to use an air tool to undo the nut.  Other than that, I've had two starters and two 85A alternators going strong for over three years now...  Knock on wood, or aluminum

 

One tip, make sure that you secure a really good ground wire between your alternator and the block.   Makes a huge diference in how they work.  Also, don't overtighten the fan belt.  You don't want it to squeel, but you don't want it too tight.

Edited February 6, 2015 by JohnS