Spridget Tech Talk (MG Midget & Austin-Healey Sprite)
Quick question,
After replacing the brake pads, rebuilding the wheel cylinders, and bleeding the brakes... I realized a leak in the master cylinder. It actually appears that its been there a while. So my question is... is the Moss "Repair Kit" adequately sufficient? (#2 in the picture below) Or should I order any additional replacement parts?
Luke,
Had the same MC on my '62 Sprite. Yes the rebuild kit should work if there are no deep score marks in the cylinder walls. Be sure to run hone through the cylinders and clean it well.
When I bought my '62 the previous owner had taken the car to a local tire and brake shop with a rebuild kit (twice) and they only changed the outside rubber and cleaned up the puddle of fluid. I could tell they never rebuilt the master cylinders because the factory paint on the tray bolts had not been broken. After a Moss kit had actually been installed it worked for several years until I sold the car.
Hope this helps.
Alan
Thanks Alan, time to place another order!
Yea... I stuck my head under the wheel well and it appears mine has also been leaking for some time. Guess I better just get it done.
I'm in the same boat with this 'new' Midget. From what I'm seeing on this, I wish I could trade back for the style on the Sprite - Simpler to service and refurb.
Good luck on it, it's really not that hard of a rebuild and it'll last for a long time. If memory serves, it took longer to bleed out the system than it actually took to rebuild the MC.
Ahh good... I'm just learning all this stuff as I go so fast jobs are good.
Good luck on your Midget! I'm only just getting my Sprite up to speed... and I sill want to buy a Midget. Too many projects, not enough time or money!
Luke,
When I did mine, I used the moss kit with no problem. Make sure you get the correct one 7/8 or 3/4. My cylinder was not very good but I honed it a lot and have never had a problem since.
Dave
If I may jump in here. what are you all using to hone the MC with? The only honing tools I've come across are those for engine cylinders (OTOH, I haven't really looked...)
Cheers,
Glen
I used a brake cylinder hone, myself. Should be available at most parts stores.
I've actually never used a hone before... any thing I should know about? (Buying/using?)
I bought a little hone off the shelf at NAPA. Put it in your drill. Low speed, go easy. Didn't help in my case, my brake bore was pitted and chewed up seals in a few miles, if in doubt, replace the MC or get it sleeved. Sudden brake failure is bad. I ended up getting a decent 7/8" and used it instead of the 3/4" (which are hard to come by).
Great info, thanks! Like Luke, I plan on working on my '72's MC this winter - it's leaking a bit and hopefully it's only a seals issue. I'll take it apart first then see if I can get by with a rebuild or I have to spring for a new one.
Luke, good luck with your project. Post some pics of the process if you can.
Cheers,
Glen
Good call Glen! I will post pics. Either in this post, or I'll make a journal entry.
Hello Glen and all,
I've completed my rebuild of the master cylinder! It turned to be only slighly more difficult a job than I expected... mainly because my directions weren't completely clear to me.
Anyways, I added a journal entry to my profile with pictures and my step-by-step process. It's a pretty simple job, but I think SEEING the parts makes things easier to visualize. It would have helped me anyways.
here is the link - http://www.mgexperience.net/journal/lukeiswho/4268
Feel free to send me any comments, or tell me if I've done something totally wrong!
Finding problems like these are frustrating, but once I fix them, it makes me more confident in being able to fix the car. It's nice. :)
I do have a check valve in there... but I kept the original in there... it wasn't in terrible shape, and the replacement was oddly shaped by comparison, so I felt like not using it. Could be a mistake.
The ones in the newer kits are different but fine I guess, I just didn't see it so I asked.
Nice work Luke. My MC is a bit different in the detals, but I'm sure the general layout is the same. Is there any reason you didn't paint the MC and mounting box before putting it back on the car (or was that just not covered)?
Cheers,
Glen
Really, I just haven't thought that far ahead yet. I want to do a lot of body work and paint to the car... but I don't know where to start, or when I'll be able to start. I'm thinking I want to replace the fenders and hood, and paint the whole car white. "Classic white" or whatever its called. But I didnt want to just have a white master cylinder all by itself. :)
But I bet it would motivate me to get the whole car done if I had one nice and shiny part sitting there!
Glen - Not to discourage you, but the dual circuit brake MC is a PITA to dis-assemble! First hazard is needing an internal snap ring plier that has a VERY long snout! Then there's getting the nylon shaft bushing out, UGH.
I did it but only out of sheer cussedness (and I nearly ruined the thing getting that bush out). THEN I found that it was severely pitted and honing didn't get it out. I put it together anyway (because it was lots easier than taking it apart and I already had the bits... cheap) but I suspect it will leak again soon.
I hope I'm wrong.
I'll cough up $130-ish for a "new" one next time.
MIke, pretty much everything I do on my cars is a PITA!. I'm not a mechanic by any stretch of the imagination (no instincts), so I have to learn everything by reading and actually doing it. I figure, if nothing else, I will go through the learning curve and gain some experience. I'll take the MC apart and, if it's repairable, I'll do it. If not, I'll get a new one. No harm, no foul.
Cheers,
Glen
Luke,
Your journal entries are really great, you're doing something good there. If you could just do your entire car and keep posting your efforts here that'd be great. It kinda seems like you're posting a modern shop manual, do the entire car and you could sell your journal on cd.
Wow, thanks Sean! I will continue to post as much as I can during my restore. This is the first car I've ever really worked on... so it will be an amateur's journal... but if nothing else, the pictures are helpful!
I did take a few pics during my brake/wheel cylinder/wheel bearing fix too... I'll post some of them shortly too.
Thanks for reading it!
Melting the bush is a good idea. Maybe next time I'll just apply a torch to the whole shootin' match! ;)
I frequently get flyers in the car at various shows from White Post Restorations that rebuild these things. Anybody have any comments about them, or any other rebuilder? Of course, the price for the rebuild is not on their website. I guess if you have to ask...
Wow! What a silly design! Over 50 years doing brakes and just disassembled DW's '76 Midget brake master cylinder. That really takes the cake as it is the worst design I've seen in all those decades. The end snap ring is typical of almost every master cylinder but the nylon ring behind it is a real bear! It had swelled and there was no way of pulling it, even by drilling and using a screw type seal puller so used the technique offered by Courtenay (many thanks as that was far simpler and safer than using a die grinder to section the ring.
I melted an 1/8" wide radial slot across the ring and then was able to rotate the ring in the donut area between piston and cylinder bore but no way could the ring be forced past the snap-ring groove even though there was no discernable burr. I even tried burnishing the edges of the groove but no joy. After melting another slot about 25% of the way around, the piece was able to be pried from the cylinder but it required a great amount of force from a screwdiver on edge. A screwdriver which would fit across the groove would bend/break from the effort.
The piece hit the metal door at the other end of the garage with a loud "clang"!
After the other pieces were also pried out, a steel ring was extracted by means of an "O" ring pick and there, in all its glory was.....the second snap ring! Can anyone explain why the "H", "E", double hockey sticks, they would do that? I cannot as we used to overhaul brake cylinders routinely years ago so I've done hundreds but never seen that bit of silly design. No one else finds it useful to do that.
In fact, it seems me that the second ring would make sealing more difficult rather than easier. Hmmm, I know! I'll bet the original design was too easy to work on and didn't leak soon enough to meet English design standards?
Before anyone gets their back up, my ancestors were Welsh so I have an in-bred disposition to teasing the English.;)
Truly a silly design though and really an unnecessary complication for the home technician. The good news is that the cylinder bores look to be in excellent condition so a simple crocus cloth lapping would seem to be all that is needed. I will have to run a hone over the snap-ring groove areas though to ensure that they are de-burred.
Would photos add anything to this? Maybe as DW's car has a single bore cylinder which uses this style kit:
http://www.raybestos.com/wps/portal/generic/productDetail?partNumber=MK1035&brandName=BDBL
The offending nylon ring is the white one in the bottom row. The one in her cylinder seems to be longer axially than the illustration.
HIH
Norm
