Lotus Elan

Alternator mount

PostPost by: Robbie693 » Tue Jul 12, 2011 9:29 am

Hello,

Following a topic in the Elan section about fitting an alternator reminded me that I meant to post about this when I fitted my new alternator recently.

I found that the mounting lugs are further apart with the new alternator and there is a gap between it and the mounting bracket. There was a comment on the other thread about the bush in the alternator lug being supposed to move when the bolt is tightened. I didn't do this for fear of snapping off the mounting lug and, instead, spaced it out with penny washers (see pic). I also had to use a set-screw as I didn't have a bolt long enough to allow for the increased reach needed.

Is this a bad bodge and have I done this all wrong?

Thanks

Robbie
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PostPost by: Andy8421 » Tue Jul 12, 2011 4:38 pm

The bush is supposed to move, but as you have identified, the lug will snap off if the bush is tight and you try to use the fixing bolt to pull it through.

You can use a bolt and a suitable size socket as a makeshift puller to pull the bush through the lug, but you will have to take the alternator off the car to do it.

Choose a socket just larger than the bush.
Slide the socket over the bush on the side of the lug that the bush is too short so that the socket bears on the lug, not the bush.
Put a bolt throught the bush and socket, then put a washer and nut on the bolt.
Tightening the bolt pulls the bush through the lug without any danger of the lug snapping off.

Trial and error - offering the alternator up to the bracket a few times will get the distance right. If you overdo it, put the socket on the other side of the lug and pull the bush back.

Good luck.
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PostPost by: UAB807F » Tue Jul 12, 2011 4:48 pm

I can understand your reticence to allow the tightening bolt push the tube through the alternator flange. I'm sure the penny washers will work fine, but as a personal thing it just looks wrong and not something I'd like my MoT tester to be looking at underneath the car. (don't give them excuses to prod elsewhere :) )

Why don't you measure the number of washers you've used, remove the alternator and then set the spacer tube in the rear flange accordingly ? You can do that on the bench whilst providing support for the aluminium flange so that it won't break off. It is (was ?) designed to move to accommodate different mounting flanges.

Brian
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PostPost by: billwill » Tue Jul 12, 2011 11:12 pm

The bush can be a sliding fit in the mount (mine is) as it does not have to provide back<->front support, that is done by the front bolt. The bush fitting provides support against twist of the whole alternator in the horizontal plane and provides the pivot to tilt the alternator to adjust the belt tension.

So you could simply ream out the rear hole in the mount until the bush is a close sliding fit or reduce the diameter of the bush by patient use of emery paper.

The rear bolt then fastens the back hole of the alternator to the bush with BOTH ends of the bush showing on both side of the rear hole in the mount. Then there is no force at all between the back lug & front lug of the alternator (no snapping force), nor any tendency to snap due to differences in expansion due to heat.
Bill Williams

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PostPost by: Robbie693 » Wed Jul 13, 2011 9:05 am

Great advice from all of you - thanks very much.

I want to replace the set screw I put in with a proper plain shank bolt so the alternator will be removed and I'll adjust the spacer. Just need to source a bolt now.

Cheers

Robbie
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PostPost by: rgh0 » Fri Jul 15, 2011 3:00 pm

The bush is not a solid tube but a slotted tube that is compressed a little by the alternator bracket so it is held in buy spring pressure of the tube and will slide relatively easily while still holding a tight radial fit on both the bolt and the alternator. I normally just tap it with a hammer while resting the alternator lug on an anvil to support it until i have clearance and then mount the alternator and screw up the bolt until the bush moves up to clamp the alternator in place, never borken an alternator yet

cheers
Rohan
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PostPost by: Robbie693 » Sat Jul 16, 2011 1:04 pm

Thanks Rohan,

I noticed it was slotted and thought about pinching it a bit at the time but decided against that incase I couldn't get the bolt in afterwards. Now I know it's supposed to move I can confidently adjust away.

I also realised after posting my last that I don't actually need a bolt do I - it's just my spacers that made the old one not long enough! Doh!

Cheers

Robbie
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