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MG TD TF 1500 - stupid brake tricks

The yard work is finished (thank goodness) after the big storm, and I had time to mess with the TD's brakes. I had gotten an idea from the BBS to flush the brake lines with acetone, (since everything else is new or rebuilt) using the master cylinder, in preparation perhaps of using DOT 5 Silicon Fluid. The non-lubricating aspects of acetone locked up the cylinder, so I had to take it off to clean it out. I used compressed air to 'blow' out the piston, but it came out while I was testing my set up, I didn't have a cloth in front to catch the parts. I found all the parts ALL OVER the garage. LOL. When I reassembled the cylinder, I used a silicon lube, but it has petroleum in it, and I'm now worried that I might have contaminated the rubber parts in the cylinder, eventually causing swelling and deterioration/failure.

I'm really, really considering flushing everything with DOT 3 and installing DOT 3 as originally planned, and staying away from DOT 5 (Silicon) or DOT 4 (improved glycol based) fluid.


Dave Braun


I did some looking on the internet. Wagner and Lockheed say they use EDPM Rubber in their brake parts and hoses.

Here is a web site that talks about the properties of EDPM rubber

As you can see, they do not recommend use with petrolium products.

I use denatured alcohol to clean out brake systems. then blow out the system with compressed air with a moisture trap atached. According to the EDPM site, acetone would work fine also.

Both my TD and B have DOT 5. My main reason is because I got tired of having to pull the brake sylinders apart every spring from the moisture they collected each winter in storage.

I also like that the paint on the inside of my rims id not destroyed by the Dot 5 as it was when I would inevitably get drips of it on the rims when bleeding.

On a similar note. On the Wagner page, I see they make a DOT 5.1 brake fluid. Others should note this is NOT silicon based.

Bruce Cunha

This is a perfect opportunity to use dot5, since everything is new. I put dot5 in my brakes when I was building my chassis, then the chassis sat in a humid storage space for 3-4 years. I bled the system last spring to check the fluid's condition, and it still looked brand new.

I change the fluid in my other cars (dot3) every 2-3 years. (Old BMW/Porsche habit.) The fluid always comes out discolored/contaminated after a couple of years. It is surprising how much brake feel improves after changing the fluid. I wish I could convert my other cars to dot5 too.

Evan Ford - TD 27621

Dave - I'm with Bruce and Evan and have been a staunch advocate of silicone fluid for years. I started the same way you did, only using alcohol and without assembling any of the cylinders prior to cleaning. I just washed all of the cylinder components and then poured alcohol through the lines and blew them out with compresse air (doing some 15 years later on our MGB, I used CRC BrakeKleeninstead of alcohol - it comes in pressurized cans making it much easier). I put silicone fluid in the TD's brake system some 25 year ago and forgot about it. In that time, I've never had a wheel cylinder fail or freeze up and have had to replace the seals in the master cylinder once, about 5 years ago. Just prior to having to replace the master cylinder seals, we had a discussion about silicone fluid at a local Register meeting and of course there was the warning that since silicone fluid does not absorb moisture, any moisture condensing in the system will collect at teh lowes point and cause corrosion. The general concensus (except for the individual stating the warning) was that there is not sufficient moisture going to condense in the small head space in the master cylinder to cause a problem. When I got home I decided to check the fluid in the TD to see if there was any discolorization from corrosion components. After uncovering the mastercylinder and taking the cap off, I wiggled into the foot space and shone a flaslight into the master cylinder and - HORRORS! There was no fluid in the bloody thing! I finally came to my senses and stuck my finger and found the the fluid was right up at the level I had filled to almost twenty years prior and it was as crystal clear as the day it was installed.

I find that there is a lot of hype regarding silicone fluid, mostly put out by companies that produde competing fluids. I have quit reading it and now go by my own experience - it works for me. For those out there that have had problems with silicone fluid, I would say stick with whatever works for you. There is even one gentleman on the MGB BBS who swears up and down that the use of "American DOT3 fluid" in place of "British DOT3 fluid" will destroy the seals. So you hear all sorts of stories. Cheers - Dave
David DuBois

Dave Braun,

Stick with your original plan.

I tried it all and unfortunately silicone is the worst. Its very invasive and will seek out the most minute crack. This means there is no latitude for wear as your fresh brake installation wears (out) over time.

I've had dot 3 in my TF for 30 years without any trouble and its not hygroscopic as some think.

But in the final analysis, as Dave Dubois says : ... For those out there that have had problems with silicone fluid, I would say stick with whatever works for you".

Gord Clark
Rockburn, Qué.
Gordon A. Clark

I'm with the silicone group. I've had it in my B now for 12 years with zero problems. Everything was apart and out of the car and I rebuilt every cylinder including the calipers. I flushed out the brake lines with methenal but in hind sight I would probably use the CRC that Dave used. I just recently put silicone in the new brake system on my TF because I don't want to have to replace 6 wheel cylinders on a T again (take a look in the Moss catalog and do the math). I did have a bit of a time getting the new brake line fittings to seal up (all new washers) and I won't be able to give it the real test until I get the car finished but I think its the only way to go unless you really need the firmer pedal and higher boiling point neede for racing. I use it for the same reason I went with stainless exhaust systems. I don't want to rebuild these again in my lifetime.


Dave - Gordon is correct, like synthetic oil, silicone fluid will leak through the slightest hole or imperfection. I had to redo the banjo joint of one of thr front brake cylinders numerous times to get it to quit leaking. I finally resorted to lapping the sealing surface of the cylinder perfectly flat, smooth and absolutely square to the bolt hole, then annealing the copper seals, so that they were soft. That finally did the trick. On the other hand, on the MGB, I think I had to tighten one joint. Cheers - Dave
David DuBois

Thanks for the valuable comments.

My biggest reluctance has been in trying to flush the brake lines because the idea of using silicon didn't really take root until I had already reinstalled the lines. They are the only non-rebuilt / renewed items in the brake system. I did flush them lazily with mineral spirits and air, but at the time I was figuring that bleeding the DOT three would finish the flush. Also, I had to remove the brake line flare bulges with a grinder, and I am concerned about the leaking fittings.

With the tub off Evan, and the engine out it IS a perfect time to hunt down those little leaks, if they are apparent, and since it would be silicon, I won't have to worry about damage.

I think I'll disconnect the lines, remove the easy ones, and flush them all with the areosol and compressed air as David suggested. I'll install the silicon (with great respect towards Gordon and others who favor DOT 3) because by nature I'm an experimenter, and although I often pay for my mistakes by having to re-do things over (heheheh a redundancy if I ever wrote one) I enjoy the process and the discovery.

Bruce's comment about DOT 5.1 is very important, something that every car enthusiast should know, even though it is counter-intuitive.

By the way, the comment I liked best was LaVerne's "I just recently put silicone in the new brake system on my TF because I don't want to have to replace 6 wheel cylinders on a T again (take a look in the Moss catalog and do the math)." Heck, I might be actually making money on this project looking at it from that perspective! Thank you all again.

Dave Braun


Since I assume you put your car up for the winter as I do. The fact you do not have to touch the brake system again after putting the DOT 5 in is really great. I literally had to take each brake cylinder apart each spring when I was using DOT 3. And there was always rust on the brake cylinder pistons.

I check on cylinder a couple of years ago and there is not a spot of rust on the pistons.

As for the DOT 5.1. I hate it when they come out with a product that can be confused with another. Why did they not just call it DOT 6 or some other number that was not close to the silicon fluid.
Bruce Cunha

More stupid MG and other car tricks: stepping on the brake pedal a couple times without a drum on. Tossing a screwdriver onto the workbench which bounces up and spears and punctures your radiator leaning against the wall. Blowing air/carb cleaner into a carb orfice while closely looking into the carb with no eye protection of course. Droping bolt into the distributor hole. And of course the time honored oil drain plug toss into the woods with the oil (many years ago- of course I recycle now).
George Butz

Bruce - Bad assumption (for which my wife would take offence if she read it - not to worry, she doesn't pay attention to the BBS unless it is something read to her by me, and they it is only about half attention), our TD gets driven year around. We don't get very much of that nasty white stuff where we live, about 100 yards up from the sound. All of our precipitation runs off as it falls and the TD came from the factory pre-shrunk, so we never worry about it getting wet. I perhaps, should have said that the brake system with silicone fluid in it has nearly 90,000 miles on it in almost 30 years, which was why my reaction to Gordon's statement regarding wear on the wheel cylinders was, huh? (no offence Gordon, your statement about lubricity of silicone fluid is correct). No wheel cylinder on the car has ever been off or even opened up since the installation of the silicone fluid. The only failure was the seals in the master cylinder about 5 years ago. I don't believe that 75,000 miles on a master cylinder is bad at all. Cheers - Dave
David DuBois

Errr- David? I think Bruce was responding to me. Since he is only one state over, I think he figures that if he stores his car in the winter, I must also. Which is in fact true. I use my heated garage at my place of business. I do appreciate your testomonial regarding the longevity of your braking system using silicon!

Bruce, In 17 years I had the joy of three rebuilds of my MC in 12,000 miles of driving. Each time there was rust. I think I hear you loud and clear!

George, believe me, I'm laughing with you... BTDT!

Dave Braun

Dave - Forgot that there are multiple Daves on this board. Dave (west coast)
David DuBois

Well, we could get formal and use Mr.Dubois, but what fun whould that be.


You bring back tooooooo many stupid human tricks. Have to laught with you also, Been there, done that.

You missed the ever favorite. Taking something out of the roof of the garage and having something drop on the fender.

Or, my favorite. Forgetting to take the socket wrench off the crank shaft gear and then turning the motor over.
Bruce Cunha

>Taking something out of the roof of the garage and having something drop on the fender.

I just did a variant of that tonight, which was pushing a tall cabinet back against the wall, forgetting that there were two box fans on top, one of which fell down onto the fender. Luckily, I heard it falling, and got in the way ... it struck my shoulder first, and just scuffed the paint. Amazingly, the scuffs buffed right out.
Mark B.

OK. Since we are owning up to the dumb things we do last week I was in such a hurry to get the sump off the engine to check the crank I flipped the engine upside down (on the motor stand) and dumped a full engine full of oil all over the shop floor. STUPID? I guess so. It took me two hours and four rolls of towels to get it up and I finally had to wash the floor down with K1 to get it clean. 8^( JL
James Lea

I think that I can out do any of the above, when it comes to stupid stunts. 25 years ago, when I was ready to start restoring the TD, my informed me that there was no way I was going to tear "her MG" apart without first getting her another one to drive. Talk about an offer, I didn't waste any time rushing out and getting a 65 MGB. I brougnt the car home and parked it in front of apron leading down into our basement garage and then started taking everything out of the trunk, including the sissor jack that the previous owner had for the car, laying all of the stuff behind the car. About then the wife ckme out to survey our new toy and I jumped into the car and asked her to watch the underside of hte car as I tried taking it down the apron into the garage. Of course, taking it straight on, the car was going to high center and the wife said stop. I stopped, put the car into reverse and pulled up off of the apron and right over the jack, flipping it up and jamming the screw through the bottom of the fuel tank! I spent the whole time we had that car trying to get a patch that would hold for more than a few months on the tank. Cheers - Dave
David DuBois

And of course the time honored 3 things a man only does "once" in a lfetime:
#3: Slamming the car door before moving the hand.
#2: Checking the radiator fluid before the car cools off.
#1: (You may have to remember way back for this one...nobody ever does it twice) Involves a zipper and the reason your mother told you to wear your underware!
No matter what age you were when you learned "that lesson" ...admit it, you have always looked "down" before zipping "up" ever since!
David 55 TF1500 #7427
David Sheward

My stupid bad luck trick was a case of extreme dumbness. I was adding brake fluid to my TF and using a small bean can formed into a funnel to add fluid. With my head in the hole under the wheel I passed out the can to my wife . Can was slippery and fell on the fender (wing) and running board. My laquer paint job was gone in a flash.
Sandy Sanders

Although i have done some beauts, my two favourites were from a BMW forum... One chap decided to change his own oil... he proceeded to drain all the "red" oil from underneath... and pour 6 quarts of Mobil 1 into his oil filler.... oops... why was there oil coming out the top of the valve cover???
The second was the chap who with a new rachet set decided to "tighten" up all the nuts under the hood...he started with the upper 3 nuts on the shock towers... "snap-damn", "snap-damn", "snap-damn"!
gordon lawson - TD 27667

Dave Braun:
You said you would remove the easy lines and flush with the Brake Cleaning Fluid recommended by Dave Dubois. This fluid is very good for cleaning, but it is a choro-hydrocarbon and it will dissolve/swell the inner coating of the flexible lines. I made this mistake and had to replace the lines. Check the archives for my experience a year or two ago. The brakes have been fine since with silicone. Ron
Ron Coates

Thanks Ron,

My rubber hoses are new, the brake lines aren't. I see your point, if I don't remove the lines, I stand a good chance of contaminating the hoses.


Dave Braun

Nothing like a good "TD/TF brake fluid discussion"....!!!!!
Think it comes down to:
Replace "all" brake lines and rebuild "all" cylinders and you have the "choice" of Silicon or regular....
Just clean brake parts and/or rebuild cylinders but leave some old rubber and you should stick with what was in there.....

In either case, you will push on the pedal and the car will stop (well, as best as it could when new).
gordon lawson - TD 27667

100% correct, as usual, Gordon.

Thanks for all the responses, and the chuckles over the stupid garage tricks!

Here is what I decided to do. I've been up to my eyeballs with the installation and training for the new unmentionable machine at work, and the open house we are planning on the afternoon/evening of the fifth (If you are around, stop by!) I finally had time to get some DOT 5. I bought a quart, because I was unsure how much I would use in bleeding. I removed all the lines and blew through them with the CRC BrakeKleen areosol which I did have on hand, and air. Very little debris or junk came out, some discolored fluid, I must have done a better job than I thought when I initially cleaned them. It did give me a chance to inspect the entire system.

I flushed out the brake master cylinder to get any traces of the petroleum enhanced silicon lube I put in there (duh!) and then added the DOT 5. It was purple! How cool is that? It is easy to see in the master cylinder, and I had two small leaks at line fittings which showed nicely with the purple tint. No banjo leaks, knock on wood, and since I misplaced my new copper washers when I assembled the system, and instead sanded the old ones flat, I was surprised.

I used the tried and true method of bleeding into a bleed jar, and had my wife come out and run the pedal a bit for me so I could check the brake action. Even though I had not added fluid to the cylinders, each brake actuated nicely. The pedal does feel a bit spongier. I plan to let the system settle down, and then I'll give it a final bleeding.

I'm glad (so far) that I switch to the silicon fluid. I think with the total rebuild, and replacement of parts, it was a perfect time to install it.

I also added a wood burning stove to my garage, It should really help in the months ahead. Otherwise this would turn into a two year project!

warmly (for real)
Dave Braun

Dave - YOu may find that you willhave to add fluid directly into each wheel cylinder in order to get all of the air out of them, since the bleeders do not bleed the cylinders. Since you did not do this ahead of time, the easiest way to do it, if it becomes necessary, is to remove the banjo bolt from each cylinder in turn and squirt fluid in using a syringe. This is a messy procedure, put will assure a brake pedal that has the minimum amount of sponginess when complete. Good luck - Dave
PS - I don't care who didn't like your mention of the unmentionable machine, I wish we could be back there to join you in hte festivities and drool over the results!
David DuBois

Thanks David!
Dave Braun

I've been away to the Bay to Birdwood Classic in Adelaide over the past two weeks and have only just had the opportunity to read these threads. My TF 1250 was restored in 1985/86 and silicon brake fluid was used. It is still there - no leaks, no problems and as far as I can see (anybody with a T will know what I mean) a regular look into the top of the M/C suggests that it is still crystal clear. I am an avid fan of silicon fluid.
Peter Daley

First stupidest brake trick:

Not buying one of those pump-up garden sprayer type bleeders long ago. You take a spare M/C filler cap, drill it for a barb, make sure any vents are plugged, hook it up and ... smile.

Second stupidest brake trick:

Using DOT 3 brake fluid and giving a zillion $ to T-series parts houses for new cylinders every few years. After silicone, no problems year after year after year. Yes, the pedal is a little bit spongy, but my wallet is stuffed.

Third stupidest brake trick:

Installing MGA front disks w/o taking the residual pressure off the front circuit. Seize-o-rama. Must take the resid valve out of the M/C and install 9lb valve to the backs and 2 lb to the fronts. After sorrow comes joy.
JM Williamson

Whew... your talking brake parts that i didn't know existed...?
gordon lawson - TD 27667

I'm in the process of pulling down the brake system on my 1500. So far it looks like I'll have to get Whites to sleeve everything. When it goes back together it will be with silicone. I'm missing some great driving weather...
D Clark

Pardon me if I'm missing something here, but isn't the driving weather in Arizona great like, 350 days a year?

Good luck with your brake system rebuild!

Dave Braun

They just add that every once and awhile so we northerners/easteners don't get too depressed!!!!
gordon lawson - TD 27667

This thread was discussed between 28/09/2005 and 14/10/2005

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