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MG MGA - Some Mechanical Questions...

Now that my brake system, motor, and transmission is installed I want to add brake fluid and bleed the hydraulic system. I don't want to order brake fluid from Moss so does anyone have a recommendation?

Is it possible to get ignition wires, spark plugs, and hoses from from my local auto parts store (O'Reiley's, Autozone, NAPA)?

Is it absolutely critical to include the heat shield when installing the carburators?

Thanks as always fellas....



gerard hutchinson

Gerard. Castrol LMA is available through my local BAP store. You might see if you have one in your area. If not, any good quality brake fluid should suffice.

Spark plugs, many of us NGK BP6ES, are available at BAP and a number of other stores.

Ignition wires depend on what you want. If you are looking for the copper cored wires, you can probably find them at any performance specialty shop. I used to purchase the wire from my local NAPA store along with the ends to attach to the spark plugs. It used to be sold in bulk form and you bought however many feet you thought you would need, attached the spark plug terminals and fitted the other end into the screw type (side terminal) cap. If you have the modern style cap with the upright terminals for the push-in style wires, any MGB wire set should work. I am using the Robert Bosch wires from my local BAP store.

Yes, the heat shield, in good condition with good insulation is needed. Keeps the heat of the exhaust manifold from causing the fuel to boil in the carbs. If your current heat shield is damaged, it can be welded up, painted with a high temperature paint and insulation attached to the back side. Mine has worked with this configuration for many years now.

Les
Les Bengtson

Gerad,
You can't use any brake fluid. Others are better versed than I on this subject, but many domestic fluids will eat your rubber brake components. Stay with Castrol LMA or, if the whole system is flushed, you can go to DOT 5 silicone fluid. There is a plethora of info in the archives on this.
Steve
Steve Meline

If the system is empty use silicon fluid if not flush it out and use silicon. Won't destroy the paint near the master. NGK plugs as above are best.
R J Brown

I've never used Castrol LMA or DOT5. None of my friends do either. No problems encountered. I'm not saying they aren't "better", just that I've never had problems not using them.

Derek Nicholson

It has been reported that DOT 3 will slowly dissolve any natural rubber components in the system. Most of the original parts, and most original replacement parts are of natural rubber. DOT 4 should be safe. Castrol LMA is just good quality product. I use this in all my cars except my B which has a new stainless brake system throughout. Here I use the DOT 5, known also as silicone, to protect my paint.
Thomas Lennon

Gentlemen - TITLE 49--TRANSPORTATION
CHAPTER V--NATIONAL HIGHWAY TRAFFIC
SAFETY ADMINISTRATION, DEPARTMENT
OF TRANSPORTATION
PART 571--FEDERAL MOTOR VEHICLE SAFETY STANDARDS--Table of Contents

Subpart B--Federal Motor Vehicle Safety Standards

Sec. 571.116 Standard No. 116; Motor vehicle brake fluids.
States the following: "S5. Requirements. This section specifies performance requirements for DOT 3, DOT 4 and DOT 5 brake fluids; requirements for brake fluid certification; and requirements for container sealing, labeling and color coding for brake fluids and hydraulic system mineral oils. Where a range of tolerances is specified, the brake fluid shall meet the requirements at all points within the range."

What this is saying is that any brake fluid sold in the US for use in passenger cars, HAS to be compatible with all elastomoters used as seals in the brake systems of all passenger cars. It also specifically states natural rubber as one of those elastometers. This requirement is also applied to any brake fluid imported from any other country to be sold in the US as a DOT brake fluid.

I have heard the BS that because ______, Fill in the country, cars use natural rubber in their brake systems, you cannot use DOT whatever in the brake system ever since I owned my first MGTD in 1959. Ironically, it first started out that the only brake fluid that can be used in any British car is DOT 3 brake fluid - anything else will rot the seals (especially DOT 4). The same thing was said about the use of DOT 5 (silicone fluid) in the Audi only that was backed up by the shop manual. That turned out to be the because of the bery small orfices in the balance circuit that was used in the Audi that would cause cavitation of the fluid and abuild up of air bubbles in the fluid. You can't use silicone fluid in any of todays cars with ABS for the same reason, but none of the reasons are deterioration of hte seals by the silicone fluid or any other fluid with a DOT specification. I personally use silicone fluid in our two MGs (TD and MGB), but most of the people I know use DOT 4 (Castrol LMA is DOT 4 fluid - DOT 4, by definition is LMA regardles of manufacture) and I know a number of people using DOT 3 in their MGs, with no detrimental affects. This requirement is also applied to any brake fluid importedfrom any other country.
Cheers - Dave


David DuBois

All, and especially Dave-
I have previously posted this, argued this, etc.
In my 40 years of extensive and sometimes commercial shop mostly British car work, I can assure you that some "DOT compliant" fluids do in fact EAT THE SEALS, and sometimes other things like hoses. I have done bench tests that proved it, in the worst cases. All the ones I've seen that do so are of American manufacture. GTLMA does not do this, in my experience.

Facts:
The DOT standards are MINIMUM performance standards. It doesn't say that the compliant fluids can't be better than required.

Most if not all manufacturers state that all seals, hoses, and fluid should be changed at some interval - typically 3 years or 30,000 miles, Nobody does it, not even me, though I do try to change the fluid itself that often or more, in cars under my control.

If this is done, then most but certainly not all, fluids will stand the test.

In my research the last time this came up, I found pictures of "acceptable and normal" conditions evidently OK by Whatever the body is that gives "Automotive Technicians" their cute little patches. I considered the pictures to represent frighteningly deteriorated seals, that I would not accept, but which I've seen all too often. These are such that the associated hoses would also be disintegrating.

I have on occasion changed black and evil American fluid in my own newly acquired American and British vehicles to GTLMA, with no subsequent recurrence of the condition. I now routinely do this.

I have never used a silicon fluid, so I've got nothing to say about that.
FRM
FR Millmore

15 years ago I rebuilt the complete braking system on a 1939 Buick using the original style rubber cups. brakes worked fine but every morning the brake lights would be on. Silicon fluid had swelled the cup in the master cylinder sufficiently to block off the miniscule return hole in the master cylinder. I had to dismantle and remove .015" from the front face of the piston. Since then I have had to do the same on several MG's.
Sandy Sanders
Sandy Sanders

IMO if you are going to change to silicone fluid, replace every rubber part in your brake system before the change. Siicone will not mix with standard brake fluids. While you can drain the system, there is already fluid soaked into the rubber cups. Silicone will cause them to swell further. Been there done that.
John H

If you don't mind the paint around your master cylinder dissolving away then use Lockheed-Girling or Castrol LMA. Do not use any other brands, especially those of US manufacture, as experience has shown that they MAY eat the seals.
With that said I will only use silicon fluid, the purple stuff, DOT 5. Installed from the start with new seals in all components. Silicon works great and won't eat paint. DOT 5 fluid cannot be mixed with any other fluid and care must be taken to get all the air out as you bleed the system.
One of the strengths of silicon is it doesn't dissolve the seals or cause them to soften and swell. This is also kind of a disadvantage as the surfaces sealed against must be truer to seal properly as the seals don't soften up to conform and seal to marginal surfaces.
Even though it is more difficult to get to seal and harder to bleed properly I feel that it is worthwhile to use the silicon as it won't attack the painted surfaces around the master cylinder.
R J Brown

One constant "truth" I've observed is that, when something changes, all advantages and/or problems from that date forward are attributed to/blamed on the change.

If you use DOT 3 or 4, changes fluids every couple of years. They absorb moisture which depresses their boiling temperature. Left long enough, they reach their maximum moisture content and rust starts.

If you use DOT 5, change fluids every couple of years. In non-sealed systems, moisture can pool and locally corrode lines/ pistons/ cylinders.

Brake fluids and OEM brake seals are designed to work together. The aftermarket parts world is a bit less controlled. If your brake seals swell in DOT 3, buy better seals. Using the same quality parts in DOT 4 may only postpone failure to a less opportune moment.

Have fun, be careful
Bill

Bill Eastman

Plugs- I use NGK V-groove resistor plugs almost exclusively. The sharp corners reduce the voltage required to initiate a spark. Gap according to the manual if you have points. I wider gap may fire but the car will eat points. Avoid platinum or other "wonder plugs" since they can't be gapped. This is less of an issue with electronic ignition.

Wire- I presently use blue 8mm MSD spiral wound in a Lucas cap with the threaded bakelite collars. I bored the collers out on a lathe to fit.

If you have a side-entry cap with the pointy screws piercing the cable, you can remove the cable's outer layer about halfway out the cap bore I usually goober a bit of silicone adhesive over the exposed fiberglass mesh and outer layer end to keep everything in place. A bit of silicon greas will aid insertion but apply it at/near the step up to the outer insulation.

I don't like carbon core wires although this is based on the dirt-cheap crap availabel in the 80's. The insulation was the real issue- it would fail with heat and/or antifreeze exposure.

pertronix sells a 7mm wire using a spiral wire and graphite-impregnated core. This sounds like the perfect solution- a "belt and suspenders" approach. However, graphite and spiral wound wires suppress RF differently and combining them may destroy both. Sounds cool though.

Have fun,
Bill

PS- avoid the original style Bosch Platinums. I've never had a car run well with these. I put NGK double iridium plugs in my daughter's Mitsu Galant since you have to remove the intake to change the back bank plugs. Yuck!
Bill Eastman

This thread was discussed between 18/02/2007 and 19/02/2007

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