MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG TD TF 1500 - Issue on brakes - wheel cylinder piston

Dear friends,
again a question to you. During the last time I found a tendency for left turn when braking. On a teststand I found out the the fwd RH brake works only 25% of that of the LH side.
After dismanteling the RH brake I found that the piston inside the wheel cylinders were blocked or works not properly.
After removing the pistons I found some sort of corrosion on the pistons. May be the material combination is the reason for that. I my case the cylinder housing is aluminum with an inside liner made from brass and the piston is made from steel. (strange, is'n it ?)
Anyway, my point is, when pulling out the piston, I damaged the dust cover. I believ this part is spot weldet onto the piston, right ?
In the Abingdon catalog I found the a replacement 31040, a piston together with dust cover. I placed an order and I hope they will have it in stock and can deliver soon. If not, I'm looking for an alternative solution. Can I build an dust cover myself ? Sure I can, turning and milling from brass or stainless steel will make an excelent replacement, but how can I fix it onto the piston ? Spotwelding is not an answer, I do not have the equippment but what's about drilling two small holes in both parts and fit it together using two countersink screws ?
Any comment ?












GK Guenter

Personally GK, I would not tamper with the brakes. Get the correct parts. If there is anything that you want to work properly on the car it's the brakes.
And while you're at it, check all the brake components and bleed the system. You may identify some more potential problems.
Stay safe!

Dan H.
Dan Hanson

Gueter - If by dust cover, you are talking about the metal cover that is spot welded to the end of the piston, your idea of drilling, taping and using a counter sunk screw will work fine, I have done the same thing myself on a brake cylinder. The problem you are having with the piston becoming stuck in the cylinder is rather common and is the result of corrosion in the brake system by the absorption of moisture by the brake fluid. The system should be flushed and new fluid installed every other year to avoid problems. Cheers - Dave
David DuBois

Thank you friends,
that will help. Fortunately I will get new pistons from Abingdon, they have them in stock.
David, yes I know that the brake fluid is an issue. Therefore I will drain compleatly as you describe and refill with DOT5 silikon brake fluid.
Any experiance in that ?
Cheers,
Guenter
GK Guenter

Hi GK,

To avoid damaging 'dust cover' in the future, use a high pressure grease gun on an adapted nipple to remove piston - detailed info in the Archives.

Hope you sort out present situation ok,

Cheers, John.
J.C Mitchell

Thank you John, I have seen it but to late ;-(((
I should think about a Laptop in the workshop!
Cheers,
Guenter
GK Guenter

It's probably obvious, but you will want to flush the brake lines and MC when you switch to silicon DOT5.

I was rebuilding everything anyway, so I removed the lines and sent brake cleaner and compressed air through them. Removing the lines can be troublesome because the flared ends bulge and interfer with the threads of the fittings. To reassemble you have to gently grind off some of the end so they fit properly back in the fittings. I also rebuilt the MC so it was pre-flushed, and I replaced the three flexible hoses. I've never tried flushing everything in place, but I imagine that with enough pints of fluid you can do a pretty good job if you bleed and bleed and bleed the system.

One more point, I was fortunate and was able to bleed my system with the cylinders in place. Since the bleed nipples are before the cylinders, some times they won't bleed properly. In that case, you may need to prefill the cylinders. I should think you may want to any way to get the old fluid out of them in advance, as they won't flush in place.

There are some fairly decent photos of the brake system in my webstite, www.dbraun99.com/mgtd15470

good luck!
dave
Dave Braun

one more obvious comment...

The front wheel cylinders have to be installed right side up to get two leading shoes on the front. Upside down (and it is easy to do) will result in really bad braking as they will then be two trailing shoes!

Here is a picture of the proper right front arrangement. Notice my springs are stretched to the longer hole positions, most agree that this is wrong, but it has been this way on my car for at least 30 years, so I reinstalled them that way.

hope this helps,
dave


Dave Braun

GK,

Pleased to read a short while back your car arrived safely in Germany.
You are not the first and certainly will not be the last to encounter the brake cylinder/piston corrosion problem.
Beware use of Dot5 silicon fluid without replacing ALL seals. If not changed the old seal can swell and stick, particularly in the MC. Quite OK to flush thro every year with Dot4. Plenty on this in the archives.
A couple of tips - sometimes you can recover the corroded aluminium cylinder with 800 wet & dry followed by SolVol AutoSol polish. Obvoiusly requires a careful clean out of the abrasive - second, when you assembly the piston apply a good coating of red rubber grease around the piston, this helps to minimise future corrosion.

Good Luck
Graham Smith
TD/C 7822
G.D. Smith

This thread was discussed between 16/07/2008 and 17/07/2008

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.