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Discussion Starter · #1 ·
I had a suspected faulty alternator bearing issue on my 2003 tbird that I posted separately and it was suggested that I check out the Alternator Rattle Postings. Having now removed the alternator, it does appear that the problem is related to the alternator rattle issue.

On removing the alternator, the small bolt on the end of the shaft was loose and there was a gap of about 2mm between the washer and the drive spyder and the spyder was able to move slightly on its spline. The threads on the bolt immediately below the head, where the washers are, are damaged giving another indication that it's been moving about.

My questions relate to the washers. There are two on the small fixing bolt: one is approx 1mm thick and 14mm in dia; the other is nearer 2mm thick and is 20mm in dia. Both washers are completely flat and neither is of the bellville type. There were no signs of any broken washer inside the casing.

How many washers are there normally, including the bellville. If only two, it's possible that the previous owner has replaced the bellville with a plain washer.

Does anyone have a torque value for the bolt.

I'll need to get a new bellville washer before rebuilding.
 

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There are LOTS of threads here regarding alternator rattle issues specific to the bolt and washers. Search "alternator rattle" or "alternator bolt."

To your question: I think the number of washers depends. Members have reported a smaller flat washer over a larger bellville washer. I had mine apart for the rattle about 4 months ago and found but a single bellville washer. I don't have a torque value for you, perhaps someone else will.

I went 30,000 miles before the rattle appeared, so I chalked it up to age, re-tightened, and have been fine for the last 1500 miles. Fingers crossed.

Some have used thread lock, but I haven't heard the results, either postive or negative, with that practice. I chose not to since the bolt was proving difficult to back out completely, and there was no point using thread lock if I didn't clean up the oil on the threads.

The curvature of a bellville washer can be subtle. I thought the washer on my alternator was flat at first, but upon closer inspection it had a distinct curve (or, maybe I just imagined it because I really wanted it to be curved?). Doesn't take much deflection to create the required bolt tension.
 

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Discussion Starter · #3 ·
Thanks tbh9088 for the response. My 2003 tbird has done less than 10K miles and I've had it 7 months. I first heard the noise soon after I got the bike and traced it to the alternator. Initially, I thought it was a bearing, but when I removed the alternator I found the loose bolt.

I've examined the washers and they are definitely of the plain flat type. I'm only guessing here, but it may be that the previous owner had the problem and replaced a damaged bellville with a plain flat washer.

I've done some digging on bellville washers and there are several different profiles. I will contact the local Triumph dealer and see if they can supply an original replacement.
 

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Discussion Starter · #4 ·
I ordered new a bolt and washers from Triumph for a 2003 tbird a got the following:

1 x Bolt - Part No T3150125
1 x large washer - Part NoT3550603
1 x small washer - Part No 3550031-T0301

The bolt thread has a 'darkish pink' coloured substance on it, which I guess is some sort of thread locking material. At first glance both new washers appear to be flat, but on feel and examination they are both definitely dished (very shallow bellville).

I re-examined both of the washers that I removed from the alternator and they are definitely flat. However, they are identical to the new washers in all other respects. I guess they have been flattened by tightening, or maybe over-tightening.

In the absence of a torque figure for the 6mm bolt, I torqued it at 8Nm.

After re-fitting the alternator, the noise, which I initially thought was a rough bearing, rather than a rattle, has gone.

I will be keeping a close watch on it.
 
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