Alternator Problem? it's gone AGAIN

[dannylt]

Nope

[MikeE]

 

bollox, looks like the new ones now gone after jist one trackday, same symptoms as before. This can't be right there's got to be a fault someone that's destroying the alternator somehow

 

Any suggestions???

 

I'll have to chase Brise for a post mortem on the old one to see what the problem is and maybe what caused it.

 

The other thing I've noticed is that my thermostat hosuing is leaking (from the filler cap) which is directly above the alternator. What would be the effectg of a bit of water getting into the alternator?

 

 

 

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[simonbell]

Interested to hear what you come up with, I have the same set up but without the water rail.......so no chance of coolant dripping into it.

 

Mine has done 9500 miles now, although it was refurbed after 4000 ish to try to eliminate a squeaking noise. I've noticed recently that there is a whining noise coming from it as well so its probably going to have to come off for a checkup before it goes completely. I did have an oil leak so I guess the innards are a bit grubby as oil was geeting onto the pulleys etc and being flicked everywhere.

 

I'm actually considering moving the alternator to the inlet side as I'm sure the heat can't be good for it.

 

Ammo also suggested there may be problems with the small pulley and suggested I fit a larger one.

 

I'm told these alternators are available for a forklift truck of some sort.......I'll try to find out and let you know but I'm pretty sure Timbo paid a lot less for his than I did for mine. He had to rotate the end plate and change the pulley but other than that they appear to be identical.

 

 

Simon Bell - Caterham 7 Duratec R

I`ve seen the future.....and it`s powered by duratec Check out the website here

[AMMO]

MikeE

 

What size pulley do you have? Some are supplied with pulleys that are far too small in my opinion, meaning that the alternator is turning at a much higher rpm than it should.

 

If you have a 50 mm pulley when the engine is turning 7500 rpm the alternator turns at around 20,000 rpm. Far too fast. I think Brise say a maximum of 16,000 rpm for the small 40 amp alternator. Even this is faster than you probably need.

 

I had a batch of larger alternator pulleys made some time ago to stop the alternators over-revving and frying themselves. I have run one on my own car since new with no problems charging.

 

AMMO

[MikeE]

Ammo,

 

Yes Danny had mentioned that to me a a month or so ago when the first one went, I'm not sure what size pulley I have but think it's the same as Danny's - I'll ask Mick to confirm.

 

cheers,

Mike

 

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[MikeE]

 

Just checked it appears to be around 60mm diameter, even so that gives 16,700 revs at 7,500rmp engine speed so probably still too high ☹️

 

What size do you reccomend Ammo?

 

And what component fails if you consistently running it too fast?

 

 

 

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[AMMO]

MikeE

 

I had some 80mm ones made. I sold the last one to Danny for his spare alternator. It is in my car waiting to go to Stuart Faulds'. I have another batch being made but I probably won't have them until the end of the month. I have another one at the machinists as a pattern as they couldn't find the original drawing. So maybe you can have Danny's spare if you ask him nicely or I can retreive the pattern one from the machinist's. Alternatively you can shop around to see if anybody else has one in stock. I do know mine have been made with the correct bore size for the shaft and the correct offset.

 

I think Danny told me that the output rose to around 17 volts with the small pulley before the alternator expired. I was convinced I had supplied him a larger pulley in the past and was surprised to see he was still running the small one.

 

My alternator runs to a maximum of around 12,000 rpm and I have no problems with charging. My car is a road car so it doesn't get maximum revs all the time like a track car. On the track where you use all the revs it is pretty essential to run a larger pulley on the alternator in my opinion. I suppose it is the regulator / rectifier that fries itself if you over-rev.

 

AMMO

[MikeE]

 

 

Thanks Ammo, I'll have to ask Danny nicely if he'll exchange it for some more info on the S/C engine 😬

 

 

 

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[AMMO]

MikeE

 

I can 'phone the machinist on Tuesday to see if they have made a drawing yet from the one I supplied them as a pattern. If so you can have that one.

 

AMMO

[dannylt]

No problem - it's not too much hassle swapping them anyway.

[mic]

80mm pullys are ideal if you use your car on the track, but if you use your car a lot on the road the alternator will struggle if you get stuck in traffic. If you are using revs of 8500 and above a large pully is needed, but anything under 8500 will be OK with a 68mm. ( which are inexpensive)

[Rob Walker]

If it regularly gets too hot then the diodes that make up the rectifier usually fail. It it is getting too many revs the bearings fail

[AMMO]

Mike

 

YHM

 

AMMO

[MikeE]

Ammo,

 

The blatmail doesn't seem to be working, could you send it direct to

 

mikeedgeuk AT hotmail DOT com

 

thanks

 

 

R400 Duratec Build and Modification Pictures

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[AMMO]

OK

 

AMMO