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MG TD TF 1500 - Brake Problem

I've driven my new acquired TD about 300 miles, and suddenly developed a braking problem. I have no braking on the right front wheel. When I attempt to brake hard, the car pulls hard left and the left tire squeals. When I check after driving the car, the left wheel is warm and the right wheel is cold.

The previous owner had replaced the wheel cylinders and flexible pipes. There are no leaks in the system. I disassembled both the right and left front brake assemblies, found no faults, cleaned, lubricated, reassembled, bled and adjusted both assemblies. I had attempted to remove the front brake lines, but they were somewhat difficult to remove, and having not yet purchased my Whitworth tools, decided to leave them assembled. The lines seem not to have any blockages, since I was able to bleed the system.

I just road tested the car, and determined that I still have no braking on the right front. Can someone suggest what the problem might be?
Corey Pedersen

How about the connecting line in front that joins the left front brake to the right hand brake. Its a metal line that is secured to the front frame cross member. Rather than remove it, disconnect both ends and blow the line out with air pressure. See if anything suspicious comes out the other end. Also it might be flatened or dented by some prior owner.
Jim Merz

Hi Corey,
have a look at the front brake cylinder on the right front through the adjuster hole in drum.
The micram adjuster should be below the cylinder. if not then the cylinders are upside down.
If they are correct then slack off one adjuster and get someone to press on the brake while you watch, the piston should move and return when brake is released.Try this with both cylinders.
If they are new cylinders then I would suspect wrong assembly.
Ray TF2884
Ray Lee

You were the "Tools" guy I see in your other post. You might need to buy a "brake pipe wrench" while you're at it if you have to remove that cross pipe. I got a reasonable set of 3 sizes at Napa that work just fine. Only one size needed, but for under $20 bucks I think and that's all they sold. Not Whitworth of course, but fit well. Not sure what size nuts they are? Someone here will know. Just don't use a regular wrench, you will eventually cause problems. (Don't ask me how I know!!)
Ed
efh Haskell

Ray, the right side front cylinder is installed with the Micram adjuster up, as you suspected. That begs the question of why the brakes worked properly for 300 miles of usage! For the sake of completeness, what is the proper orientation of all six cylinders? I apparently need to check each of them.

Ed, I have several sets of flare nut wrenches. My SAE and metric wrenches didn't fit the brake line flare nuts; why would SAE and metric flare nut wrenches fit any better?
Corey Pedersen

Corey - Did you disassemble the cylinders on the right front wheel? They piston could be frozen in the cylinder as a result of a small amount of fluid leakage and moisture. This is a pretty common failure mode on the T series brakes, particularly on a car that has not been driven a lot.

As for the flair nut wrenches, See the chart, Wrench Size Comparison in the Other Tech Articles section of my web site at: http://homepages.donobi.net/sufuelpumps/ to see if there is a 'close enough' fit in your SAE & Metric collection. If not, you can always make you own flair nut wrench by getting the proper size Whitworth box end wrench and cutting a chunk out of business end. Cheers - Dave
Daved DuBois

Hi Corey,
the front brake front cyl has the adjuster below the cylinder and the rear one above. This means the shoes have a self-servo action multiplying brake effort.
If the back brake hand brake lever is pointing then that end is correct.I think the back can only be upside down if the brake plates are on the wrong side of the car.
The first time I came across the front brakes being wrong was on a friends car,a dislocated thumb was the proof!
Ray TF 2884
Ray Lee

Ed, I did remove the cylinder internal parts. They were clean and free-moving.

Ray, I will reverse the cylinder installation. I'm very curious as to why the brakes functioned adequately for the 300 miles I've had the car, and then suddenly began to malfunction. Could you clarify your description of the rear brake arrangement?

Corey Pedersen

Dave, I took a look at your website. Wow...lot's of good info!

Ray, I studied the service manual. The cylinder orientation you made reference to is confirmed by the sketches of the brake assemblies, though it's not obvious, and I found no directions in the text. I would imagine that a lot of people get this wrong.
Corey Pedersen

Corey, I just checked my flares. They are indeed Evercraft SAE's from Napa. All I remember is the smallest one fit great. Maybe because it was a brand new set of pipes from Moss?

As far as Dave B's web site, not just a "lot of good info". You could build a car from scratch following his site! I know because I did just that!

Ed
efh Haskell

elf Haskell
As far as Dave B's web site, not just a "lot of good info". You could build a car from scratch following his site! I know because I did just that!

I'll second that! There's a lot of Daves knowledge in my TF. Super guy for letting us tap into his knowledgeable brain! PJ
PSJ

Hi Corey,
I missed an important word out"down".
The handbrake lever should point down, but yours must be correct or the cable would not line up
Ray
Ray Lee

I started disassembling the right side brakes. Ed, I checked my flare nut wrenches and they definitely don't fit the TD flare nuts. As you stated, your aftermarket flare nuts are probably not Whitworth. It's a major nuisance trying to work without Whitworth tools (I have them on order). I've got everything apart, except for the bottom bolt on the rear cylinder. I've yet to find a tool that will securely grab the bolt head. I may resort to grinding a spare SAE open end wrench to the correct size.

Ray, I checked the service manual for the assembly details for the rear brakes, and the pictures clearly show the Micram adjuster position relative to the cylinder.
Corey Pedersen

Fellas, Corey went to Dave DuBois' website, which does have fantastic information. But thanks much for the endorsement.

Corey, my website which Ed and Paul are talking about has a chapter on brakes with all the orientations shown. You may want to check it out, http://www.dbraun99.com, you may find it nearly as helpful as Mr. DuBois' site.

warmly,
dave
Dave Braun

The problem persists!!!

I disassembled the right front brake assembly, removed and blew out the hard and flexible lines from the front three-way to the right front brake, and reassembled with the cylinders in the correct orientation. I checked the left side front and determined that the cylinders were correctly installed. I adjusted the right brake assembly, and bled both of the front brakes. I test drove the car and still have a pull to the left. I can make only the left side front tire squeal when I do a hard brake application. After the test drive the left drum is hot and the right drum is warm, but cooler than the left drum.

What next!!!
Corey Pedersen

Hi Corey. Thedrums shall not be hot sfter a drive, If so, the brake are on all the time.
Jack up the front of the car, and the wheels shall "roll" freely.Adjust the brakes so the liners just tuches the drums, and 1 notch back.
thoralf. Norway TD 4490
Thoralf Sorensen (TD4490)

Thoralf/Corey - I tighten each adjuster down hard first, so the wheel is locked up - that centers the shoes in the drum. I then loosen the adjusters 1 notch, so the wheel spins freely.

Tom Lange
MGT Repair
t lange

The drums are hot because I make repeated hard stops during my road test. The shoes are adjusted correctly as per the shop manual, and the drums turn freely after adjustment. Any other ideas out there! I believe they are assembled, adjusted and bled correctly. Any other ideas out there. This is getting very frustrating!
Corey Pedersen

ppears that
cj schmit

Jack the front of the car up so that both front wheels turn freely. Have your wife press on the brake pedal until the left front wheel won't turn. Try the left wheel and see if it turns - if it does, have her press harder to see if the right will ever lock up. If it does then have her release the pedal and then press until the left shell again stops rotating. While she's still pressing the pedal, adjust the right front brake until the wheel stops turning. If it will rotate after she release the pedal then you should be good to go.

If the right front never locks up when the pedal Is pressed id swap the linings from side to side.
Gene Gillam

If the brakes worked and quit, then something has changed. If one side works and the other does not, and there is no obvious oil, fluid etc on the one that does not, then it is a hydraulic problem. This can only be an obstructed brake pipe, and/or fluid ports at the fittings or cylinder(s). Most suspect is the flex, but a piece of rubber in the steel line could be the cause. Open the lines and blow through them to check/clear steel lines. Flex lines may appear OK when not under pressure - ie bleeding - but block off when system pressure is applied.

FRM
FR Millmore

FRM, the cylinders, pipes, hoses and fittings have all been removed and cleaned. There were no blockages.
Corey Pedersen

Sure sounds to me like one of the cylinders is partially seized. This would account for no brakes on the offending side until the foot pressure is increased. In addition it would account for the shoes partially staying on when the pedal is released causing the hot drum.
Hugh Pite
H.D. Pite

Hugh, that was my first theory, I disassembled the wheel cylinders and the bores look brand new and the rubber and pistons move freely in them.
Corey Pedersen

I'm going to try Gene's suggestion today. Any other ideas while I have the car on the lift?
Corey Pedersen

Hi Corey. Have you tried pressing the pedallightly with the drums off and see if there is any movement on the shoes.Don't press hard or your piston will fly away,
thoralf. Norway. Td 4490
Thoralf Sorensen (TD4490)

How old are the flex lines? I've had a couple old vehicles before restoration, where one flex line came apart inside and created a valving effect shutting off the outward flow on one vehicle to the wheel cylinder and inward return flow on the other vehicle, causing a sever drag on that brake. One day they were fine, the next day they were messed up. Both of these vehicles sat for 20 years or more. PJ
PSJ

To follow up on PSJ's comment: there should be a date code stamped on the rubber flex lines. Make sure they are reasonably new. Adjustment: Turn the adjusters to lock the wheel/drum. Then push on the pedal as hard as you can a couple times. See if the wheel is still locked, try repeating a time or two. This will center the shoes. Line up the adjuster hole so you can see the end of the cylinder and adjuster. Have someone step on the pedal and verify that both cylinder pistons are indeed moving. This is a really strange deal, so look for strange things, like a big crack in the drum or something. A TD or TF with proper brakes should leave 4 even skid marks when stopping hard on a cement surface. So check this in case the left front is prematurely locking. George
George Butz



The flex lines are new.

Per Gene's suggestion, I had my assistant lightly apply the brakes as I turned the tires to try to sense any difference side-to-side; there was none.

I removed the hubs and swapped the linings from side-to-side. I then road tested the car. At first, the right side locked, and I assumed I had found that the problem was caused by faulty linings. This was odd, because I had found no apparent contamination or leaks in the brake assemblies. I then continued my road test, making about twenty hard stops. After the first two or three stops, the brake pull no longer occurred. I now have normal braking. The only sense I can make of this is that the original right side linings (now on the left side) were contaminated, and that repeated hard stops have eliminated the contamination.

This has been a S/L of work, but on the bright side, I can now disassemble/reassemble/adjust/bleed TD front brakes (both sides) in about twenty minutes (with my eyes closed)!
Corey Pedersen

Congrats Corey...way to stick with it...and thanks for the follow-up.

And I apologize for the misspellings in the original post. I was typing on my phone and it's hard to hit the right keys all the time...glad you could follow what I was TRYING to say.

Gene

Gene Gillam

This thread was discussed between 07/09/2012 and 09/09/2012

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