MGB Register Forum

A few years ago I had the problem that the starter could hardly turn the engine over. I immediately suspected the battery was dying but it was the original starter that was dying. A new geared starter solved the problem. Now I have exactly the same effect, I again first suspected the battery but that is fully OK. Can't be the relatively new starter motor? Turned out the earthing strap under the floor had developed a bad connection (dirt, rust).
I would have thought the best place to connect a strap would be the engine block itself but it would have to be a very long strap to reach any bolt in the bodywork under the car. There are a few likely looking bolts on the bulkhead and not far from the bellhousing - would that be a good idea?

happy emjeeing folks

Hi Norman,
Welcome to our forum.

I have an earth lead that runs from the battery earthing point. Then to the gearbox support and then to my gearbox. Unsure if I ever had a earth fault but....... never had an issue.

Just got a couple of black earth leads from halfords. I cannot remember the length 18" + 12" something like that.

I can put a low voltage multimeter anywhere on the car and have no resistance.

Hope it helps.

Regards
Paul

My 1980 car has the earth strap bolted to the top of the back plate of the engine block with the other end under the mounting of the oil pressure feed pipe junction on the flat part of the bulkhead beside the pedal box.(This is how it came from the factory),
Cheers
Charles

Hallo Paul,
with gearbox support I assume you mean the crossmember? One of the two bolts towards the centre - I assume these screw into captive nuts -?
I guess a strap direct to the battery earthing point is the optimal connection albeit very long.

happy emjeeing
Norman.

Hi Norman,
Crossmember is probably a better word

It' was the cheapest/quickest way for me at the time. The bolts must go into captive nuts. Took a bolt out cleaned my fixing point then carried on to the rear of the gearbox connecting to the engine.

I also felt connecting at another body point just created a better earth fot the whole car. That was my thoughts on the crossmember body mount.

I work on domestic appliances and there are always earth points wired from here to there. But everything is usually screwed together joining everything up. Just my preffered way of doing it.

Going from the battery to starter would make sure the starter is getting full power

Regards
Paul

Hello Paul,
my idea with a strap from the crankcase to the bulkhead was meant as backup not a replacement. I have now got a nice new strap in braided copper and will throw the frayed original steel thing out.
Judging by what I have read here and there BL didn't really know where to put the earthing strap either.

Thanks for answers.

The main earth for the starter motor, is on the left hand side (nearside in the UK) of the engine and connects the front mounting plate of the engine to the body side of the engine mount. This picture shows the arrangement: The usual issue that stops this working is the braided strap frays and has too high resistance or over zealous painting of the engine plate or mounting to body. Both these areas have to be paint free, and clean. The faces the starter motor bolts to must be clean and dry also. This is especially important if changing the starter motor on an engine that has seen a lot of service and is oily in the this area.
I don't think adding a strap from the gearbox crossmember centre bolts will help the issue as the gearbox doesn't have a metal to metal contact and the crossmember has 4 bolts connecting it to the body anyway.
Pete

When I rebuilt my 18V engine, the original earth strap on the gearbox was fine but slightly frayed. I decided to replace it. Never being one to under engineer a repair, I fitted 4 new straps, one across each rubber mounting. At least the engine ones are easy to check now. I did make sure the new leads bolted to clean metal too.

hi Pete,
" the gearbox doesn't have a metal to metal contact "
It's firmly bolted to the crankcase, you can't get more metal-to-metal than that - and the crossmember has 4 bolts to the bodywork, should make for a decent contact.
Starts a treat with the copper strap.
cheers, Norman