Poor (at best) braking on my TC - advice requested

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pleask
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Poor (at best) braking on my TC - advice requested

Post by pleask » Sun Jun 17, 2018 3:46 pm

I did a full restoration of my '48 TC about two years ago, the brakes have never been even close to what I think they should be taking in to account they are not the best to start with, I understand that. When I push on the brake peddle with all my might I "slow down" and come to a stop eventually, which is just not good enough for me.

A few things you should know first:
- No signs of oil or brake fluid on any shoes
- Shoes (all new) properly adjusted (shoes kiss the drum when rotated)
- Rebuilt wheel cyl's with new pistons
- Rebuilt M/C with a good angle on the push rod
- New (copper) brake lines
- The drums were not turned by me, no idea what their history is and no idea what the thickness tolerances should be (do you know?)

I was told at a car show today that a new set of Alfin brake drums would work wonders, as they are for sure round, and thicker so I'm not possibly loosing travel distance on the shoes due to thin drums. The cost of them is a big out lay of cash if I'm not positive they will solve my issue.

Any advice or suggestions are welcomed!
Thanks all, Pat

Tom Wilson
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Re: Poor (at best) braking on my TC - advice requested

Post by Tom Wilson » Sun Jun 17, 2018 5:37 pm

Pat, do you know what material your brake shoe linings are? Years ago I had the same problem, and solved it by changing to a much softer lining. I used Green Gripper, available through many sources. http://www.scanpac.com/cm/pdfs/tds-GGW.pdf.
Personally I think it’s the best improvement you can make to a correctly set up brake system on a T or MMM MG.

Tom Wilson
Zionsville IN
With 3 TCs and lotsa MMMs

Norman Tuck
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Re: Poor (at best) braking on my TC - advice requested

Post by Norman Tuck » Mon Jun 18, 2018 8:27 am

I installed Alfin style drums made by Bob Grunau, and they improved the braking remarkably. I believe that the original drums are made of steel that "polishes up" The Gruanu drums are aluminum alloy with cast iron inserts that do not become polished.
I also installed the softest linings that my brake shop could supply, and I believe that was helpful.
However, In my opinion, even though the brakes are much improved, by any modern standards they still "suck." I am often terrified, but I have always been able to stop in time, so far.
Norman

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Steve Simmons
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Re: Poor (at best) braking on my TC - advice requested

Post by Steve Simmons » Mon Jun 18, 2018 8:48 am

The brakes on my TC are great. Not anything like modern brakes, but they do stop fast enough to throw my passenger forward. If I stand on them I believe I could lock up the wheels, although it's been a long time since I tried that. So I've never subscribed to the "TC brakes are terrible" belief.

My changes from stock are Alfin drums and modern semi-metallic linings. Soft, organic pads are recommended by Bob for his Alfin drums because the semi-metallic material will wear the iron drum liners more quickly, but I'm happy with the braking and since I drive a lot of steep downhill canyon roads (at speeds which cause my passenger handle to get a lot of use) I worry about the softer linings fading. Perhaps I'm worrying about nothing. If I were using my TC merely for coffee runs then I would definitely go for the softer shoes, as they probably work better at cooler temperatures than my current ones do.

With brand new pads and old drums, you may also have a contact issue. The arc of the drum will be larger than stock, so the arc of the shoe might be too small. This means only the middle of the shoe will be making contact, and without the leading edge you may be losing a lot of grip.

Another issue is that the original steel drums can bow outward as you press harder on the brake, especially if they are heavily worn. You may want to have the drums measured and replace if they are too far worn. I don't recall the maximum amount of wear, maybe 60 thou? If they are worn, you can find good used sets, install the Alfins, or find a set of Datsun aluminum drums and have them drilled for the TC bolt pattern.

When I installed the Alfin drums and new shoes on my car, braking was improved somewhat but it wasn't the night and day difference that some people have experienced. My only real complaint is that they weigh a ton compared to other options, but the quality is good.
1949 TC8975 / XPAG 9609
1949 TC9849 EXU / XPAG 10507
http://www.mgnuts.com

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Duncan M
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Re: Poor (at best) braking on my TC - advice requested

Post by Duncan M » Mon Jun 18, 2018 11:56 am

I thought the Alfins (being finned) were supposed to dissipate heat faster/better? In that case the softer pads like the woven https://www.mcmaster.com/#brake-lining/=1dcaw35 (at bottom of page) should be a natural for Alfins. If woven (softer) pads are used with original drums, you might need to be more careful. In the past most have gone with Alfins because they were the only easy alternative to running oversized (thicker) pads with worn original drums.

All 4 drums are identical, except the ones on front wear faster than the rears.

Pat did not mention new flex lines. Some people claim the normal "rubber" flex lines expand under braking. Story is the SS braided outer flex lines that Moss and other places sell in a set have an inner tubing that will not expand. That is the only night and day difference I have heard reported, aside from proper bleeding. I have heard other pretty good reviews of the softer pads in a TC.

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Steve Simmons
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Re: Poor (at best) braking on my TC - advice requested

Post by Steve Simmons » Mon Jun 18, 2018 12:10 pm

I've used both rubber and braided hoses on various cars (not the TC) and found the difference in pedal stiffness is somewhat noticeable but not a night and day difference. I actually prefer the rubber hoses for reasons I can elaborate on if anyone cares. You can't gain more braking power using braided hoses, but you can get a stiffer pedal.

The Alfins should, in theory, cool better than the original drums. But in my opinion they aren't going to cool so much more that the pad material would require changing. Especially in a street-driven car. I guess the real test would be to put one of each type on the front of a car, go down a long grade, and immediately measure the temperature of each. Then drive another minute or two and measure again to see the cooling rates.
1949 TC8975 / XPAG 9609
1949 TC9849 EXU / XPAG 10507
http://www.mgnuts.com

Tom Lange, MGT Repair
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Re: Poor (at best) braking on my TC - advice requested

Post by Tom Lange, MGT Repair » Mon Jun 18, 2018 1:26 pm

I'm not particularly a fan of braided brake lines because they are either OK or burst - there is no weakening, no symptoms, no warning. With the rubber hoses there is some warning than not all is well.

On a race car it is different, but on a street car I am hesitant.

Tom Lange
MGT Repair

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Steve Simmons
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Re: Poor (at best) braking on my TC - advice requested

Post by Steve Simmons » Mon Jun 18, 2018 2:17 pm

I had a braided hose let go once, backing out of a friend's driveway. I stopped the car with the hand brake just before I rolled into traffic. Three miles prior I was exiting a freeway at 70 MPH toward a busy red light. It could have been really messy. Now before you think to yourself that any hose could let go, the problem was that the steel braiding had broken apart from flex (it was the line between the chassis and rear axle on a single circuit system) and the edges of the braiding then cut through the hose over time as it flexed back and forth. There was no way to see it coming because it all happened underneath the metal crimp. I never ran braided hoses again.

I agree on a race car it's different. You replace those hoses a lot more often than on a street car, and the slight improvement in pedal firmness is far more useful.
1949 TC8975 / XPAG 9609
1949 TC9849 EXU / XPAG 10507
http://www.mgnuts.com

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Duncan M
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Re: Poor (at best) braking on my TC - advice requested

Post by Duncan M » Mon Jun 18, 2018 3:42 pm

I think a lot of people prefer the SS and rubber wrapped teflon flex lines because they are shiny. I prefer the look of rubber flex lines. In theory, the teflon should last almost indefinitely, unless it has a manufacturing error as Steve described. When moss has their good sale, the teflon (SS) are only about $20 more than the rubber set. Plenty of vintage race cars use rubber flex lines.

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Steve Simmons
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Re: Poor (at best) braking on my TC - advice requested

Post by Steve Simmons » Mon Jun 18, 2018 5:16 pm

I don't believe the hose that failed me had a defect. It appeared to me that the constant flexing as the axle went up and down caused the stainless mesh to snap, simply from too much bending back and forth. Then the ends of the broken mesh slowly wore through the rubber and then the teflon. The hose didn't burst, it simply spring a leak. The pedal went to the floor about one second after I felt the brakes engage, so I guess you could call it a "medium sized" leak.
1949 TC8975 / XPAG 9609
1949 TC9849 EXU / XPAG 10507
http://www.mgnuts.com

Warmuthb
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Re: Poor (at best) braking on my TC - advice requested

Post by Warmuthb » Tue Jun 19, 2018 4:56 am

TC brakes can be hard to bleed. Particularly when using silicone fluid. I had to bleed mine out three times before I could get an acceptable pedal. The cast iron drums and proper lining material also helps, but I have been able to have acceptable results with the original steel drums. Remember, while not modern 4-wheel discs, when new these cars had very good brakes and they are not a large heavy car to begin with ( plus many folks never drive their car at top speeds). It is possible to have totally acceptable brakes in a TC.

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searunner
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Re: Poor (at best) braking on my TC - advice requested

Post by searunner » Tue Jun 19, 2018 9:49 am

I have the brake system totaly NEW during my TC rebuild

new shoes are more efficient new carbon mixture increase of 200°/ the sliding friction
BUT more friction can be a problem with steel drums -more heath can cause the distortion of steel
is for this that I am looking to find good iron drums to solve this theoretic problem...
(on my drive style brakes are used rarely, probably this depend to my motorcyclist past)
BUT in the emergency it must be effective
I have looked to AlLFIN and also
DATSUN NISSAN Z240 compatible but require a lot of works
The ideal .for the TWO front drums - or for all FOUR .can be this
http://www.mg-parts.co.uk/index.php?rou ... oduct_id=4
Probably I will buy this for my TC front drums

NOTE
No personal interest in Edney business
Internal diameter of Drums must be 228,8 or 229,0 mm
Attachments
datsundrum.jpg

pleask
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Re: Poor (at best) braking on my TC - advice requested

Post by pleask » Wed Jun 20, 2018 6:47 am

Thanks all, great reading and all on topic. I am on a Morgan run right now so no a lot of email time so ive been quiet. I have decided to get the Alphin drums with new shoes from Bob and be done with it. I can't afford it, but i can't afford not to.
Pat

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Gene Gillam
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Re: Poor (at best) braking on my TC - advice requested

Post by Gene Gillam » Thu Jun 21, 2018 7:34 am

You won’t regret it, Pat.

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