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MG MGB Technical - MG NewB questions ????????


I have a 71 Roadster and I have a few questions if anyone can answer them I will be grateful.

1. The Tachometer has 2 mileage fields a top and a bottom the bottom field seems to work fine but the top field numbers just spin randomly what is this field used for and is the tachometer faulty..... ?

2. The oil temp gauge seems to jump around a lot is that normal is there a problem??

3. How can I tighten the hand brake??

4. At one point the high beam [blue light] light was working but it seems to have stopped working I have checked the bulb and it is fine...??

thanks

Richard
R A Holst

Ok I can't answer 1,2, but 3 and 4 I can. To tighten the handbrake you'll need to go under the car first. Near the fuel pump is a grease fitting for the hand brake line (grease it first) the tensioner for the hand brake is on the rear most side of the rear axel. It'll look like a small box with steel cables leading to either side of the car. With the hand brake fully engaged check to see if the wires are loose. If they are you can pull them in somewhat and retighten them at the block. If they're tight (no slack at all) and you feel that the hand brakes not working as it should take a close look at the hand brake cable (remember where that grease fitting was right?) and follow along it to see if it might be kinked at all, it shouldn't be but you never know. If its not go back to where that cable leads to the block and adjust it there. If you can pull on the cable and nearly pull it out 3 inches or more you'll need to replace it because it'll most likely be broken.

4: Check your wiring for loose connections, or a bad ground. Clean them up using steel wool and diaelectric grease. It should work but if it doesn't use a check light to see whats what in those wires you might end up needing to replace one of them is all.
CJD Dark

I hate to disagree with our freinds from the colonies, but I have a 71 B too and I think the hand brake ajustment is on the other end of the hand brake lever under the car. You should ajust the rear brake drums first though. This is quite simple, just jack the car up so the wheel is just off the ground, put an axle stand or a pile of blocks or bricks under the sill just to make sure the car doesn't fall on you head approach from the rear and you will find a peg about 1/4 " square at the top of the back plate, this is the ajuster. Srew in 1/4 turns until the brakes are just rubbing. When you have done both sides you can ajust the cable with the thumbwheel at the front.
I don't have an oil temperature guage just oil pressure (that jumps about a lot) and water temperature (which doesn't). These are a combined guage with two needles and scales. The oil pressure should read 15 psi at idle and at least 55 psi at 3000 rpm when the engine is red hot. The water temperature should move slowly to just past the N and then drop back as the themostat opens. This takes 2 or three miles as the car warms up. If this reading is irratic then its either a faulty mercury capilary or guage or else your cooling system needs flushing. If you do indeed have a oil temperature guage then I can see no reason while this should be irratic.
The other gauge you refer to is the odometr (speedo) I think the milometer is the top scale and the trip recorder is the bottom one. There is a thumbwheel on the end of a short cable to zero this which is located just under the dash imediatly below thw instrument.
My advice to you is buy a Haynes manual from Halfords.
Paul Hollingworth

On the hand brake adjustment I have to go with Paul. I just replaced the rear axel on my 71 GT so I replaced the hand brake cable as well. The adjustment is next to the drive shaft at mid point of car.
Get a manual, will save your time and sanity.
Ron
R Garcia

The top field in the SPEEDOMETER not tachometer (tacho counts the engine revs), is the trip mileage recorder. It is operated by a knurled wheel that hangs down below the instrument, except these are often snapped off. If it rotates randomly it is obviously bug***ed. Reconditioned units are available if you want to change it.

It is normal to see the oil gauge flick while the engine is idling, but it should be steady when driving, although it will fall as the oil gets hot. The flicking is a combination of the way the pump works and the pressure relief valve cycling. In a more modern car, if you had a gauge, it would be damped so the flicking doesn't show.

I agree with the others, the first thing is to adjust the rear brake shoes, then the cable. Buy a Haynes manual in Halfords - well worth the money. The rear adjusters will be very stiff and possibly seized. Buy a proper brake adjuster spanner or you will ruin them.

Warning bulb - probably poor earth. Clean as already recommended. Haynes manual shows wiring circuits to help you understand where the current flows to and from.

Mike
Mike Howlett

4. Do the high beams actually work? If not then the problem is more likely to be with the dip switch. If so has the tell-tale fallen out of the back of the speedo? The ground for it is shared with a whole lot of other stuff including the tach and the instrument lighting so if these are working it won't be the grounding point but could be in either wire to where they join others in the main loom, or the bulb holder. How did you check the bulb? They are very dim at best and can hardly be seen at night under street lighting, let alone in daylight.
Paul Hunt

Before fussing with the hand brake adjuster (which is right at the bottom of the hand brake handle), try adjusting the rear brakes. Since there are no self adjusters for the rear brakes, they need to be manually adjusted periodically in accordance with the shop manual. Rear brakes that are in need of adjustment will cause the hand brake handle to have to be pulled up much further.

Additionally, as long as you are under the car, on the rear left side of the rear axle housing is a pivot arrangement for the hand brake cable. Disassemble this pivot and clean and lube it. This will help measurably in making the hand brake hold better. Good luck - Dave
David DuBois

This thread was discussed between 18/04/2004 and 19/04/2004

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