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MG TD TF 1500 - Why A Disk Brake Conversion?

I'm seeing this more and more and am curious if this is a necessary conversion. I have new everything on my 55TF chassis and the brakes work perfect. Even converted to DOT5. I know disks will not fade like drum brakes, but not willing to drive at 70 plus mph in this car, why would I need them? Shoot me some stuff, I'm all ears! PJ
Paul sr

;-)


L E D LaVerne

Depends on how hard you want to drive it Paul. I'd drive mine a lot harder in the mountains if I had disc's. The drums are probably equal to the disc on a single panic stop. Not so with a lot of on and off braking. The drums will fade pretty quick which is why you gear down...I do in any car for that matter .
L E D LaVerne

To be fair Paul,

I can lock up all four wheels if I stand on the brakes with my drum my brakes.
Apart from the possibility that they will not fade due to heats - what is the point?
I don't drive anywhere near the level where that will be an issue. Even going down Mt Washington.

TD's and TF's were given pretty good brakes I believe and they still hold up in todays traffic.

If you want to race or drive beyond the intended scope of the car - then maybe you need to add a little more braking power. A Larger engine or other makes may help with that decision.

I for one and very happy with the way my 17cwt car stops as is.

just my 2c worth.

Rod
R D Jones

Thanks gents, that's all I wanted to know. Glad I didn't waste my money. I always gear down, even in the B. Of course a panic stop is another story and hopefully very infrequent! PJ
Paul sr

No, it isn't necessary, but some people still find mental comfort in having disc brakes. The only potential real-world advantages are a slightly reduced pedal effort and better modulation. On the flip side, drum brakes have a firmer pedal feel and allow you to adjust the "play" in the pedal which makes heel and toe driving more comfortable.

That said, I've driven my drum-equipped cars many tens of thousands of miles, in both mountains and in heavy traffic, and I've never experienced a situation where any of the cars would not stop quickly enough. Drums will fade sooner during repeated high speed stops, but even driving as hard as I dare in my local (very steep) canyon roads, I never experience stopping problems.

If you're driving so hard that your brakes are fading then converting to discs can introduce a new problem - uneven fade. The hotter the brakes get, the more imbalance you will encounter as the rear drums begin to fade. But again, I doubt anyone is driving their T-Series at that level of punishment on public roads so I don't consider it a worry.
Steve Simmons

Steve wrote: "....which makes heel and toe driving more comfortable."

I've been driving the TF a lot during this driving season after the restoration, and find that I have been using the heel and toe technique with more frequency. I was surprised the first time this happened when my right foot went into a heel and toe move without any conscious thought of doing so. I hadn't used a heel and toe technique since my high school days when we drove, and practiced, like we were race car driver wannabes. And for me this was in a '55 Chevy. Palm Springs, CA and all of those empty desert roads in the late '50s and early 60s made for teen age driving paradise. And yes, doing a heel and toe in the TF is much easier than it was in the '55 Chevy.

John
'54 mgtf 0781
"Meeker"
John Brickell

"Why a disk brake conversion?" "Why not?"

The original twin leading shoe front brakes really are on par with the disks, so braking performance is not a valid reason/excuse.

We elected to go with them because they came with the MGB rear end/gearing I wanted, along with the euro splined wire wheel adapters. Since I swapped to the disc brakes, I also departed from original by plumbing a dual brake circuit.

Another reason- they get lots of comments!

One good reason to stick with drums- less drag! On a Honda forum focusing on high fuel mileage, I inquired into anyone converting the front discs to drums for less drag and better mileage. Boy, did the morons come crawling out of every nook and cranny!

We have our Miata up for sale (wife wants a blue one instead of red) and the potential buyer walked away tonight, BECAUSE the rotors are a bit rusty from sitting for years.

I'm currently in the process of painting her Fiero. I've wire wheeled the rust off the rotors, but, after it has been driven and the brakes applied, you still cannot rotate the wheels by hand... and I've exercised and bled the four calipers extensively. Brake drag is one of those dirty little secrets Detroit does not want to discuss. (That particular GM hand brake was a bad joke, too.)

By the way, I'm working up a patent for a disc brake system that not only would be virtually drag free, but would eliminate boosters, use corrosion-proof plastic caliper cylinders, be self bleeding, utilize plastic tubing and spring loaded "push lock" fittings, last the life of the vehicle and feature water/antifreeze instead of brake fluid. Why don't we have that already? (hint- $$$$$)

If anyone asks, tell them you have genuine, bonafide, twin leading shoe front brakes, better than disc brakes! You can even rivet new linings onto the shoes. We don't have that technology today!

Have I confused you yet, Paul?
JIM NORTHRUP SR

I could imagine you'd need more pedal power since the disc brakes are not self reinforcing. I had that impression on early disc braked cars without a brake booster.
What for me always speaks for discs is the easy exchange of the pads, it's just so much less hassle and no adjusting needed

Mike
Mike Fritsch

I truly understand most of the technology behind disk brakes. They become popular after WWII on aircraft, especially jet fighters because of their long landing roll at high speed with the brakes on. It was common to see the rotors cherry red after a landing, drum brakes would be useless in that situation. I can see them on race cars, especially road course cars that do a tremendous amount of hard continuous braking. My curiosity stemmed from guys converting to disks on these cars and how safe are they without them. LaVerne pretty much answered my question. The area he lives in should represent a good test on a cars braking system and his TF has drum brakes. In my area, the mountains here are ant hills compared to Colorado! I'll keep it in it's original state and have no worries. Thanks for all the input guys! Much appreciated. PJ

Paul sr

Here's a 4 disc carbon brake cutaway from a business jet. The first time a mechanic handed me a rotor from one I almost hit myself in the face it was so light! A brake job is several hundred thousand dollars so rather than just overhauling when worn out, we pay a maintenance plan based per landing.




J E Carroll

Paul:
I have driven T-series for over 40 years now and only once had brake fade. 30 years ago we drove our TD over the 'Highway to the Sun' (Logan's pass) pulling a small trailer with our camping gear. On the way down the brakes got mushy and then faded to nothing before I could find a spot to stop. We ran to 6,500 RPM in third gear and were a hair's breath away from blowing the engine and being totally out of control. I would have paid anything for disk brakes at that point. Fortunately there were no traffic and the TD handled the curves on the last few miles, and we made it safely.
Lesson learned . . . slow down and gear down before going down. I have often done this since in the TD, TC, and TF and have never had a problem again. If your engine will pull you up the hill it will hold you back on the way down if you just give it a chance by gearing down soon enough.
Godspeed in ‘Safety Fast’
Jc
John Crawley

Running MGA disc brakes for a few years now and can say without a doubt it was the best upgrade on the car I could have done. I tend to drive mine a little hard when I do run it and the brakes do not fade out like the drums did. I know it is not stock but then neither is a 5 speed. it is the individual expression of what one wants I guess. I like em.
Tom Maine

If you want disc brakes or a five speed gear box buy a Mazda MX5 or modern MG TF. I recently sold a 1932 MG M Type and many of these, and MG J2s, were fitted with Ford engines in the 1960s. An original OHC MG engine will now cost over £10,000 to return a car to as it was when it left the factory. How long before original TD/TF gear boxes and brake components are in demand?

Jan t
J Targosz

If your brakes are fading on public roads, then consider uprating the linings to a harder material. Also new cast iron drums will make an improvement, as well as ensuring the rear brakes are operating properly so added stress is not placed on the fronts. The only other thing that will cause them to fade is boiling brake fluid but I'd say it's more likely the linings.

With Alfin drums and uprated linings, I'd put my TC's brakes up against a disc conversion any day. And remember TCs do not have the twin leading shoe design of the TD.

We have very, very steep and twisty roads in my area and I've never managed to fade these brakes. On the other hand, I have faded my MGB disc brakes on those same roads! The cause was the front pads overheating.
Steve Simmons

Oops, lost part of my post somehow. I suppose I was just saying that it's worth looking at how your car is set up versus your performance needs.
Steve Simmons

Yes, I did not want a Miata or any other modern car but to bring mine up for freeway driving. As to motor costs, I am glad I live in the US. New Crank, venolia pistons and crower rods as well as boring engine was way under the 10 grand you would spend in Europe. I just wanted to make sure the engine would run as long as I am able to drive it. The new crank is great.
Tom Maine

Because disc brakes are better than drum brakes, period. & I drive my TD @ 80-100 MPH too much of the time.
(Don't let my wife or the police know)!!!
Len Fanelli

MeThinks someone in CO. may drive that fast also..
Tom Maine

Jim Northrup: For drag free disc brakes you might want to look at what Jaguar used in the mid sixties. They had a retracting pin in the caliper piston. Not sure how it worked though.
John F. Quilter
1965 Jaguar 3.8S
John Quilter (TD8986)

Len,
Our TDs belong to my wife and she routinely cruises in excess of 80mph, tailgates at those speeds and never leaves any margin of safety.... those are big incentives to go discs. Wait till I get her 1466cc engine with your roller lifter cam under the bonnet with the blower!

Jan T
Wife has a Miata- it hasn't been on the road in the last 5 years, like her Fiero. She always drives a TD as long as there's no salt on the roads.

John,
There have been lots of caliper tricks patented and tried, as in 2 piece and double acting pistons and such, but nothing really retracted the pads. I drew up a tiny spring loaded cylinder that acts as a hydraulic accumulator to retract the piston back a tiny fixed dimension, but that still won't retract the pad unless it is fixed to the piston and that would open up a can of worms.
JIM NORTHRUP SR

MeThinks someone in CO may drive that fast also.

Hmmm, Now I wonder who that would be? Grin.
Paul sr

I think the car is green in color?
Tom Maine

And has a three hole cup holder in the TF's arm rest...
John Brickell

I went down a steep mountain grade in my TF go-cart style (engine off). After not too many stops (was able to completely release them now and again) they faded, but stayed reasonable enough to just require more pedal pressure. That said, I could certainly smell them. After about 1 or less miles on the flat, they were cool enough to restore regular braking.

I wouldn't mind discs, but the idea of changing the look behind the spokes doesn't do it for me. Until I have a safety reason to change, I'll likely leave my drums. As others have said, I can lock up all four if I want to. Seems good enough for me.

Alex
55TF-1500
Alex Waugh

This thread was discussed between 22/08/2013 and 26/08/2013

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