Jump to content
zambo

How difficult to refurb your master cylinder?

23 posts / 972 viewsLast Reply

Recommended Posts

My car will be off the road shortly for a full body and paint treatment and I was thinking, “how hard can a master cylinder refurb be”.

 

I know this is a key component to saving your life, but looking at the rebuild kits, there doesn’t appear to be a lot on them to replace.

 

I understand there are bores to inspect for pitting, etc. but was interested in who had done this and their experience. I like to think I’m relatively handy around an ‘02.

 

Thanks Richard

Share this post


Link to post
Share on other sites

I never done this task, but glancing at procedures doesn't seems to be difficult....

Brakes including MC overhaul covered in section 7 (Brakes) 

and quick snapshot of procedure for MC

1975816856_brake1.thumb.png.a6c0b66742ac9352f1dd1d73e01b00d6.png771414951_brake2.thumb.png.81844e3de93b53c834564af5564658fd.png1057911057_brake3.thumb.png.1596e038bd3db561f34423b4e6683177.png

Share this post


Link to post
Share on other sites

MC refurbs are easy.

call Blunt. or IE.

provide credit card.

get NEW MC in mail a few days later.

throw 50yr old used MC , probably pitted from lack of fluid flushes, in shop trash bin.

done.

Edited by mlytle
  • Like 4

Share this post


Link to post
Share on other sites

As Marshall says..... the main problem with refurbing your BMC is the pitting.  I used to sell rebuild kits but found that over half the people buying them ended up buying a new BMC anyways, due to having pitting in their core BMC.  

 

Rather than support a process that took two weeks, created more headaches, and cost more money, I just stopped offering the kits.

-------------------

 

Now you can have the BMC re-sleeved, but then the pricing isn't all that different than a new one.... for now.

Edited by AceAndrew

Share this post


Link to post
Share on other sites

I’ll have to check what RHD versions are worth new and a source. Appreciate the responses though.

I’ve installed a number of overhauled (professionally) or new ones over the years and certainly one of the easier jobs you can do on the cars, but I was thinking with time on my hands it might be a suitable interim project.

But given the projects that are currently before me, prob better I utilize the time for these.

Share this post


Link to post
Share on other sites

I can’t say from experience of this specific master cylinder (the RHD) but I have resealed lots and lots of other designs and wouldn’t be concerned about doing it  now (with a few provisos). I would say that I have had variable results in doing this and it probably characterised my earlier years working on cars when I was more inclined to take the cheapest option regardless of other factors. These days, as parts become more expensive and harder to find I would certainly consider it again (I have some spare brake calipers that I am going to reseal when I get chance). I would also give the RHD master a go at resealing, mainly because of the cost from Jaymic for even a refurbed piece but most likely, I will get it re-sleeved locally when I need to fix it again. It’s a good advert for flushing your brake fluid periodically. 

 

A few generic tips:

 

Absolutely check that the new seals that you get match the master that you have in hand. Depending upon the source for the kit it may not be that reliable. Some I have repaired in the past have had dozens of different configurations for what looks like the same master. 

 

Strip it down, take pictures and note how it goes together. Clean all the parts with brake cleaner / make sure any little drilling’s are clear etc. 

 

check the bore. Rust is obvious but you can also get a ‘wave’ in the bore due to wear. The temptation is to get a cylinder hone and hone any imperfections away but there is a good chance that you end up taking the bore wider than the correct tolerance for the seals so there is barely enough flex on them against the wall of the bore to hold a seal throughout the travel. Gauging this is tricky and this is where I have gotten variable results in the past. Anything that you can feel with your fingertip inserted into the bore (assuming you can get it in!) May be more than you can safely remove. This is why re-sleeving is a good idea as it gives you a consistent, in spec bore to work with. 

 

Re-assemble with clean hands using only brake fluid as a lubricant. You can also use specialist rubber greases for brakes but I still like to keep that off the sealing surfaces (though it is good to smear on other surfaces where you don’t want it to rust.). 

Share this post


Link to post
Share on other sites

Done it many times, as well as the clutch M/C, slave, front calipers and rear cylinders too.

 

If you are going to hone, be sure to get the fine grit stones, lube with something like WD-40, but hone just a little bit just to clean it up. If there is rust / pitting upon inspection, then perhaps new should be considered.

 

I will counter that on '02s and E30 M3s I have replaced hydraulics (febi & ATE) and had them fail in less than 10K miles. Brake M/C, clutch M/C, and slave. Rebuilt the OE I took out and no problems......

 

It is your call, but if it fails, then you can blame yourself and no one else.

 

Generally for me the trade off is in the time to rebuild vs. cost of new; if I have the time, sure, if not, then new parts keeping the old and rebuilding that for future inventory in your parts hoard.

 

At the very least, take it apart just to see how it works.

Share this post


Link to post
Share on other sites

Couple more thoughts:

3 hours ago, mlytle said:

throw 50yr old used MC , probably pitted from lack of fluid flushes, in shop trash bin.

Pitting is the difference between a rebuild that takes and one that leaks from the get-go.  If you can feel pits in the area that's traversed by the seals, then follow above advice.

 

If you're in the States, there are several places that will sleeve and then rebore the cylinder casting to its proper size.  Some do with brass, others with stainless steel.  White Post Restorations in VA is one; look at Hemmings on line for others.  If you're outside the US, I'll wager you can find a shop that can do the work.  

 

One more thought--installing a nice, tight, pressure-holding M/C is gonna make the slave cylinder the weak point, and it'll start to leak sooner rather than later, so consider replacing it at the same time, unless it was the new part that caused the M/C to leak!

 

cheers

mike

Share this post


Link to post
Share on other sites
Couple more thoughts:

Pitting is the difference between a rebuild that takes and one that leaks from the get-go.  If you can feel pits in the area that's traversed by the seals, then follow above advice.

 

If you're in the States, there are several places that will sleeve and then rebore the cylinder casting to its proper size.  Some do with brass, others with stainless steel.  White Post Restorations in VA is one; look at Hemmings on line for others.  If you're outside the US, I'll wager you can find a shop that can do the work.  

 

One more thought--installing a nice, tight, pressure-holding M/C is gonna make the slave cylinder the weak point, and it'll start to leak sooner rather than later, so consider replacing it at the same time, unless it was the new part that caused the M/C to leak!

 

cheers

mike

 

Good points Mike. I’m planning on buying new rear cylinders and the calipers I’ll get rebuilt.

 

I’m in Oz so the RHD thing makes it way more expensive to buy the MC new/rebuilt than in the U.S. and LHD markets generally, so getting it rebuilt locally is the best option if I don’t have a go myself.

Share this post


Link to post
Share on other sites

I have rebuilt both LHD and RHD brake masters..I would say the RHD is a bit simpler... The instructions for the LHD kit from ATE are rather generic and the end seal orientation depends if it's a direct servo mount cylinder (like on our cars) or remote like idunnowhat.

Bore surface quality is key, hone it with 800grit taped to a long bar mounted in your electric drill.

If the cylinder is seized, block the spare outlets & pump the pistons out by connecting your grease gun to the front outlet...don't try to whack the pistons out by slamming the cylinder, you can break the casting and ruin your whole day.

Share this post


Link to post
Share on other sites

I think there are specialists on the Gold Coast that are well regarded for resleeving masters and other hydraulics. 

 

 I think Raj May have gone there ( @rapandi )

Share this post


Link to post
Share on other sites

Thanks Simeon.

 

I had BHSS TBS in Capalaba overhaul dual boosters, master cylinder and calipers on an E3 I restored several years back. They did a great job.

 

This was more a question around anyone’s personal experience doing the MC themselves.

 

There are a few reputable shops that can do the work in SE Queensland I’m familiar with.

Share this post


Link to post
Share on other sites

Doing a "master cylinder refurb" ...... piece of cake.  

      With that said, I've done only one on my '74tii (and several on my '48 Chevy truck). 

 

I was exceptionally lucky on the '74tii for 2 huge reasons: 

1)  I was able to easily find a master cylinder rebuild kit.  (I've heard rumors they are now no longer available.)

2)  there was no pitting in the cylinder bore.  Just some clean-up effort with 2,000-grit sandpaper cleaned out the crud.

 

Cheers,

 

Carl

 

Share this post


Link to post
Share on other sites
9 hours ago, zambo said:

I’m in Oz so the RHD thing

none of that info was in your post, nor is it in your profile.  if it was in your profile at least, much of this discussion would have been more useful.....

Share this post


Link to post
Share on other sites

back in the day it was a very common procedure. we used to recondition clutch master, brake master and slave cylinders. but the cars wear much newer and the cost offset was much higher. just to give an example replacing cv boots is kind of a thing of the past its much more cost affective to just replace the whole axle. but if you have never reconditioned a tii brake master cylinder and your compitand i think you can pull it off 

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.




×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.