VW4X4

Sleeving wheel cylinder

Recommended Posts

Warning: anyone using stainless steel to sleeve wheel cylinder!

  One major issue I have is dis-similar metals.  My wheel cylinders were all sleeved with stainless steel (SS).  The pistons in them are  all Aluminum (AL).  Turns out if you don't use the vehicle much, within a few months the wheel cylinders are stuck, because of corrosion.  This is  a major issue between raw AL and SS. This is exactly why a lot more stainless is not used in modern vehicles today.   I'm trying to find a simple solution for this.   The work was done by

Applied Hydraulics. I wish Applied Hydraulics would have warned me about this .   They did a good job , and at very reasonable prices but missed the boat on this problem.   Anyone have  a simple  solution to my AL/SS corrosion problem? 

 

Share this post


Link to post
Share on other sites

Yes, this has been brought up before. That would be "Apple Hydraulics". Wish I had the answer other than driving the vehicle more often.

Share this post


Link to post
Share on other sites
28 minutes ago, keiser31 said:

Ok, the place I had mine done is now called:  http://brakeandequipment.com/

         Use to be Allied Hydraulic......  Not the same place....

 

Yes, this has been brought up before. That would be "Apple Hydraulics". Wish I had the answer other than driving the vehicle more often.

 

Share this post


Link to post
Share on other sites

The problem here is that you are trading regular corrosion and pitting for galvanic corrosion.  Cast iron and aluminum are relatively compatible from a galvanic standpoint, but obviously the cast iron cylinder rusts and pits easily from any moisture in the brake fluid.  Stainless and aluminum are more reactive (specifically, the stainless increases the galvanic corrosion in the aluminum) but the stainless sleeve won't rust and pit like the cast iron.  Unfortunately, brass sleeves with aluminum pistons are even worse from a galvanic potential. Of course, the solution is to ensure there is no moisture in the brake fluid. Naturally this is difficult, especially with DOT3 fluid.

 

In the aeospace world we have a similar problem when we use stainless fasteners in aluminum parts. In that case, we typically use fasteners that have an aluminum coating on them. This unfortunately won't work for brake cylinder sleeves.

Share this post


Link to post
Share on other sites
3 minutes ago, joe_padavano said:

Joe,   Thank for the info.  I'm slowly convincing myself that the only good solution is  making new pistons out of some other material.  If I use stainless, I think I might run the risk of gaulding. If I use plain CR steel, I could have the new piston plated with  a yellow  Iridite  or a znic Chromate treatment.   Not sure what would be best here, but one thing for sure this is, its not going to be cheap or easy, and I for like to find someone who knows more about this than I do in order not be wasting any more money.

 

 

The problem here is that you are trading regular corrosion and pitting for galvanic corrosion.  Cast iron and aluminum are relatively compatible from a galvanic standpoint, but obviously the cast iron cylinder rusts and pits easily from any moisture in the brake fluid.  Stainless and aluminum are more reactive (specifically, the stainless increases the galvanic corrosion in the aluminum) but the stainless sleeve won't rust and pit like the cast iron.  Unfortunately, brass sleeves with aluminum pistons are even worse from a galvanic potential. Of course, the solution is to ensure there is no moisture in the brake fluid. Naturally this is difficult, especially with DOT3 fluid.

 

In the aeospace world we have a similar problem when we use stainless fasteners in aluminum parts. In that case, we typically use fasteners that have an aluminum coating on them. This unfortunately won't work for brake cylinder sleeves.

 

Share this post


Link to post
Share on other sites

Let me guess, you did not fill the fresh system with DOT5?

 

I have not seen this effect on my cars with SS sleeves, aluminum pistons and DOT 5. Have others noticed this?

Share this post


Link to post
Share on other sites

Did you use brake assembly lube ?

 

I've always had Apple sleeve with brass. However, the same stuck pistons can happen with brass sleeved cylinders. It just takes longer. And to an even slower extent, the aluminum can corrode and stick to the  cast iron bores of new wheel cylinders.

 

The way to prevent that is first coating the clean bores and pistons with brake assembly lube. I use EIS brand.  Whatever is in it prevents corrosion of the aluminum pistons.   Since I learned of that many years ago,  not one has seized since.

 

BTW, brake assembly lube is not the same lube designed for the rubber parts, which won't prevent piston corrosion. However, brake assembly lube  can be used on the rubber parts without harm. 

 

And yes, you should first use assembly lube even with DOT 5.

 

Paul

Edited by PFitz (see edit history)

Share this post


Link to post
Share on other sites

My experience is with brass sleeves. The aluminium corrodes because of the proximity of the brass, which contains copper. It is galvanic corrosion. It still occurs with the original cast cylinders, but much more slowly because cast iron is further up the galvanic series than brass and stainless steel. Some SS is above brass in the galvanic series, but most is below it. So whether SS sleeves are worse than Brass depends on which type was used for the sleeve.

 

I always assemble with rubber grease. They still corrode over a few months if I don't drive it. It is the presence of oxygen and an electrolyte (water) that promotes the corrosion so I suppose I am being too stingy on the grease!

 

DOT 4 brake fluid is less hydroscopic than DOT 3. DOT 5.1 is less hydroscopic than DOT 4. DOT 5 (silicon) is not hydroscopic at all and is not compatible with DOT 3, 4 or 5.1.

Share this post


Link to post
Share on other sites

The rubber grease is just for preserving the rubber parts of a brake system, but does not prevent the aluminum corrosion that brake assembly lubes do prevent.

 

If you want to use just one, then use the assembly lube for pistons, bores, and the rubber parts.

 

EIS, Permatex, and Bendix each make a brake assembly lube that at least one of those brands you can get at most autoparts stores, or online suppliers.

 

Paul

Share this post


Link to post
Share on other sites

My 69 Vette calipers were sleeved with SS at least 25 years ago. Still has the same DOT 5 fluid in the system from then. Never a problem. Dot 3 is spawn of the devil.................Bob

  • Like 2

Share this post


Link to post
Share on other sites
6 hours ago, PFitz said:

EIS, Permatex, and Bendix each make a brake assembly lube that at least one of those brands you can get at most autoparts stores, or online suppliers.

Thanks Paul. I was working with advice given to me many years ago by someone who I cannot remember. Clearly there are (and probably were way back then) better alternatives.

Share this post


Link to post
Share on other sites

I liken DOT-3 to lacquer paint and leather seals ; yesterdays technology.     I use Brake and Equipment Warehouse in Minneapolis MN. They are keenly aware of the different types of stainless steel.

Share this post


Link to post
Share on other sites

VW4X4.

Did you tell them the pistons were aluminum before having the SS sleeving done or did you just tell them to sleeve them with stainless steel with no other input.

Share this post


Link to post
Share on other sites

Is my thinking wrong here; if the pistons have brake fluid running by them the seals are leaking and there is a bigger problem. 

  • Like 1

Share this post


Link to post
Share on other sites
15 minutes ago, Curti said:

Is my thinking wrong here; if the pistons have brake fluid running by them the seals are leaking and there is a bigger problem

 

Yes,  if the seals become worn. Or scored by abrasive that was left in the pistons if they were cleaned with  sand paper or emery cloth.

 

Or, if the bores are not coated with assembly lube and they become corrosion pitted, then as the brake lining wears and the piston and cup move toward the end of the bores to take up wear, the cup lip could move to pitted areas of the bore and then leak.

 

When brake fluid leaks past the cup lip, if enough leaks past it will bulge the rubber dust boots.  If it becomes alot of fluid trapped in the boot end of the cylinders it can pop the  edge of the dust boots off the cylinder and you'll have brake fluid running down onto the drum and linings.  

 

Paul

Edited by PFitz (see edit history)

Share this post


Link to post
Share on other sites

Lancia Aurelias of the 1950s were made with bronze pistons in aluminium bores.  The only problem that I have ever had is unavailability of Metric seal sizes to suit.   I have had the bores all sleeved with stainless to available inch standard,  for instance, 25 emu size is now one inch.  I made new bronze pistons to suit the one inch stainless bores.  Diameter of pistons is 3 thou less than the bore size.   (The thousandth of an inch is the most useful unit of measurement for fits and tolerances.  Metric measurements have specific usefulness for scientific purposes.   Essentially, you use units of measurement that bear a sensible relationship to what you are dealing with.   In the early 1970s,  the most ignorant, despotic lawyer politician in our history made law that Australia should convert from imperial to his hero Napoleon's metric measurement system, without referendum.   I derisively refer to millimetres as ethnic measurement units, or emus; emus being large flightless birds who function more on instinct than cognitive ability.)

Edited by Ivan Saxton
sleep deprivation (see edit history)

Share this post


Link to post
Share on other sites

Off topic but ....Interesting take on metrication. We did the same thing is about 1972. If you are working in decimal inches, they are easy. But most people work in inches and fractions so arithmetic becomes pain in the tripe.

 

Another thing, in this country and perhaps in yours, land titles were measured in links. Areas were in acres, perches, poles etc. (aaaaarrrggghhh!) Engineering surveys were in feet. What a pain it was. So when we went metric, us surveyors had ingrained in our heads some conversion factors: 1 link = 0.201168 m = 7.92 inches. 1 foot = 0.3048 m. It is surely a lot easier if it is all in the one unit, decimal metres. But I often still say something is about 4" wide or whatever, rather than 100 mm or 10 cm.

Share this post


Link to post
Share on other sites
21 hours ago, Spinneyhill said:

Off topic but ....Interesting take on metrication. We did the same thing is about 1972. If you are working in decimal inches, they are easy. But most people work in inches and fractions so arithmetic becomes pain in the tripe.

 

Another thing, in this country and perhaps in yours, land titles were measured in links. Areas were in acres, perches, poles etc. (aaaaarrrggghhh!) Engineering surveys were in feet. What a pain it was. So when we went metric, us surveyors had ingrained in our heads some conversion factors: 1 link = 0.201168 m = 7.92 inches. 1 foot = 0.3048 m. It is surely a lot easier if it is all in the one unit, decimal metres. But I often still say something is about 4" wide or whatever, rather than 100 mm or 10 cm.

 

I understand the floating between worlds, Metric or English.  Much of the car business is metric, but get measurements in both systems and are constantly converting.  I have gotten pretty good at converting both ways.

Share this post


Link to post
Share on other sites
On 27/12/2017 at 11:31 AM, Ivan Saxton said:

In the early 1970s,  the most ignorant, despotic lawyer politician in our history made law that Australia should convert from imperial to his hero Napoleon's metric measurement system, without referendum.

Hmmm. The metric system was not Napoleon's. "

Napoleon himself ridiculed the metric system, but as an able administrator, recognised the value of a sound basis for a system of measurement..."

 

See the Wikipedia article on History of the Metric System.

Share this post


Link to post
Share on other sites

A few decades ago they were going to convert the USA to metric. Didn't happen.

Anybody remember the  "Metric Ain't American"  bumper stickers?

Share this post


Link to post
Share on other sites
23 minutes ago, JACK M said:

A few decades ago they were going to convert the USA to metric. Didn't happen.

Anybody remember the  "Metric Ain't American"  bumper stickers?

Don’t throw away your metric wrenches, SAE is still alive but metric is out there too in big numbers.

Share this post


Link to post
Share on other sites
2 hours ago, JACK M said:

A few decades ago they were going to convert the USA to metric. Didn't happen.

 

Worked on any "American" vehicles built in the last 20 years or so?

  • Like 3

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.

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.

Loading...