The 'Big Fuse' and associated problems

[Nicholas Blair]

arebrec said:

big fuse on the cerb has gone twice in a year.

Have just ordered and received steve Heaths big midi fuse and a new box

same here - busy weekend ahead.....

[markh1]

not had a problem with mine but I think I will get a spare one now for LeMan. Can you get them at Halfords??

[FarmyardPants]

Some poeple don't bother with the fuse at all, most cars don't have one. A compromise is to put two fuses in. Very important to clean the contacts and do the nuts up quite tight. If the connection is poor the resistance goes up, the fuse gets hot and cracks.

[mikesr]

markh1 said:

not had a problem with mine but I think I will get a spare one now for LeMan. Can you get them at Halfords??

VWP do the strip fuses and the holders.

[markh1]

mikesr said:

markh1 said:

not had a problem with mine but I think I will get a spare one now for LeMan. Can you get them at Halfords??

VWP do the strip fuses and the holders.

I have looked on the site and I cant see a 100amp blade fuse, the only 100amp ones I can see are the midi and maxi fuses. Are these the ones that I want?

[arebrec]

or

Steve Heath engineering website

[markh1]

arebrec said:

or

Steve Heath engineering website

Thanks for that, just ordered a fuse and holder from them just incase!

[The Dogster]

For the sake of future issues I share my experience

Thought I'd buy a new trickle charger for the winter - left it on for a couple of days - run the car every weekend if not lashing down

Car running perfectly until 2 weeks ago I plan to take it for the weekend 50 mile spin - start engine and battery/ignition warning light stays on - ok so I pull off drive and away we go - all normal apart from the warning light.....then looked at rev counter and needle was stationary.....did the drive and came back on drive.

Interrogated this site (which is brill) and it suggested that symptoms led to the "Big Fuse"

Ordered 3x new standard fuses and 2x standard fuse holders from TVR (Parts for TVR's
) Parts Ltd - just over £20 came next day

This afternoon removed scuttle panel in engine bay - disconnected battery and proceeded to investigate - when I popped open the cover of the plastic fuse holder the fuse did look a little "bent" to put it as accurately as I can - when I undid the 2x retaining nuts for the leads came off and the fuse broke as I did it - suggesting it was very weak. I studied the fixings and decided to remove the whole Alloy bracket that the fuse holder is attached to - clearly the best option as too fiddly and tight to attempt to undo the 2x fuse holder nuts/washers and bolts - everything came out ok in one piece - I locked carefully in vice and removed fuse holder from alloy bracket

Now I could see where the old fuse holder had become very hot at some point and clearly (I think) where the issue lay) - see pics





Here are some other pics to help







Finally in place



Scuttle back on - battery connected - fired up and all worked - battery/igntion light goes out and rev counter works - took for blast and so far all ok


Thanks to this site all remedied until the next challenge - thanks all Nigel

[Nicholas Blair]

Great thread resurrection 👍😂

[notaping]

I got fed up with failures of this fuse. None of which were electrical, but all mechanical due to vibration or water ingress. I ended up mounting a more robust holder on the wiper mech box - which gives real easy access.

[Mr Cerbera]

Gordon, I have to say, the quality of your work is outstanding.

Good Man

[notaping]

Thanks Paul. Not quite sure I'd go that far - but I try :-)

[The Dogster]

Yes much better solution

[FarmyardPants]

The Dogster said:

Don’t the big fuse cables carry high current +ve charge? Those eyelets look very close to the (grounded?) mounting bracket etc.

Edit: not to dis your handiwork, just wondered if it’s well isolated

Edited by FarmyardPants on Wednesday 16th December 22:00

[Penelope Stopit]

notaping said:

I got fed up with failures of this fuse. None of which were electrical, but all mechanical due to vibration or water ingress. I ended up mounting a more robust holder on the wiper mech box - which gives real easy access.

Nice job

An observation.......When the fuse holder is mounted on the engine it will vibrate in frequency (if that's the word for it) with the cables that are attached to it

With the fuse holder mounted on the bulkhead the cables will vibrate at a different frequency to it and may over time loosen the terminal nuts

Wonder if nyloc terminal nuts would be better?

[notaping]

The problem with the original fuse holder is that the cables are mounted on the same terminals as the fuse. So the vibration from the cables is transmitted straight through the thin metal of the fuse itself. Also the cheep plastic housing offers very little support.

I don't know yet how long my solution will last, but the cables are mounted on separate terminals from the fuse - giving the fuse some isolation from vibration, and with the fuse being encapsulated it should be more robust in any case. Hopefully :-) In addition the housing is twice the size as the original and much more rigid.

Time will tell . . .

[Penelope Stopit]

Yes fuse should be ok as it's built for the job not like the original strip type fuse, was thinking about loose nuts

[Byker28i]

The fuse location has always been ridiculous. I mean to relocate mine sometime, even suggested it after the rebuild and the engine rebuild but it wasn't done. It's interesting to see a different location for it.