Thats the way these jobs should be done.
Excellent work!!!

7 hours ago, nta16 said:

On the Midget I had a about 2 years or less old rear wheel slave cylinder go overnight whilst the car was parked at a national show, great to see as I arrived first thing in the morning and meaning no more passenger rides for donations to charity.

 

Ouch. That's a really unfortunate situation.

 

You warned me about rubber parts and I saw it firsthand right after your warning. Impressive.

 

Two years ago I used best parts I could find because it's a brake job.

Thanks for the rear parts being compatible with VW. I found most of the parts from VW stores.

I used Meyle drums, Topran stub axles, Bosch brake pads, Bosch spring set and Swag bearings.

Brake cylinders was TRW.

This was one of the their boxes.

 

This time I didn't have time to search. The part I found and installed now is this:

 

 

If you can see it from the pictures I posted above, they have a difference in their design.

The TRW has a narrower middle section. Maybe it was a fake part and not original TRW.

 

I disassembled the removed TRW cylinder, here is a picture:

 

Old caliper carrier:

 

Old hoses:

 

Hoses were replaced before.

Rears are identical. Dated from 2017.

Fronts are different. One is from 2019, other one has no info on it.

 

DIY bleeding bottle and the color of the old fluid:

 

 

3 hours ago, Thefeliciahacker said:

Thats the way these jobs should be done.
Excellent work!!!

Not without the invaluable help I get from here.

 

You warned me about lower grade bolts and I found one 8.8 used in one of the caliper pins.

I don't know if you can see it from the picture but it's very slightly bent!

 

So it's very important to use proper bolts!

 

I mentioned M10x45 bolts before for the caliper carrier but it's not the right size.

Correct size is M10x28 for >93+ models. I read the wrong size from size from catalog. Please be informed.

I had to cut the bolts for the carrier but I know the heat generated when cutting the bolts is not good. So I'll buy and replace the bolts with the proper size. It's very easy.

 

For future readers, here are some extra notes about the work:

 

First of all, the brakes are important for your own life and the other people. So if you have any doubt, don't attempt to this work yourself.

I used a torque wrench for critical bolts like stub axle, caliper carrier etc. I recommend using a torque wrench.

 

I used thread locker liquid on critical bolts that will endure heat. Like caliper carrier and caliper pins' bolts.

 

Do not, never ever attempt to do this job with an open ended spanner on solid lines' unions. You WILL strip them! 100% guaranteed.

This will render the car unable to move. The damage could be repaired only by a brake specialist with brake line building tools so you will be in a sh...ty situation.

Buy this spanner. You won't regret it.

 

 

It is called brake line spanner. The size is 11.

On the flex hose side I tried using open ended spanner first but when it felt like it's about to strip, I used a ring spanner.

 

 

If you can't insert it from one end you can always cut the old hose. You will trash it anyway.

 

 

Deal with the spilled brake fluid.

Brake fluid WILL KILL your paint work! Don't touch the car with brake fluid spillage on your fingers.

Even one tiny drop of brake fluid will damage the paint!

 

Removing the brake union spring clips may be hard. They could be rust-seized or they could have small stones stuck beneath them. They could have been painted with anti-corrosion stuff.

I used this method to remove them:

 

If you remove the union first, it will be easier.

To remove retaining clip, I used WD40 to lubricate the hollow between the clip and the body extension. Then I tried to insert a small screwdriver between the flex hose head and the retaining clip. I used a hammer to gently tap to the screwdriver.

If it's not moving, try this:

 

Add more WD40 and gently squeeze and release, squeeze and release. Your Aim here is to help WD40 find its way inside.

 

After that, I tried to tap the screw driver into that location before and it moved the clip outwards.

I continued with a larger screw driver that I could turn after tapping it between the clip and the hose's head. After moving it enough with help of the screwdriver you can pull the rest with pliers.

 

I used Bosch Superfit to lubricate the caliper pins, piston/brake pad touch surface, front brake pad side friction points and rear brake pad side friction points.

 

 

For anyone who needs the correct size for the rear drum gasket this is the size: 40 . 52/58 . 7.5/01

 

 

Tbh I've used open ended spanners before as long as they are not corroded. 

10 hours ago, R_Blue said:

solid lines' unions. You WILL strip them! 100% guaranteed.

 

Are made from Brass?

On 27/04/2023 at 22:00, R_Blue said:

The TRW has a narrower middle section. Maybe it was a fake part and not original TRW.

Sorry but TWR is one of those companies I was writing about before, an old brand name no longer manufactured as in the past. Now part of  a company called ZF Aftermarket in the UK at least.  The quality of TWR brake parts was described as variable in 2017 (and later) at least.

 

As an example Lucas, a very famous UK company of the past, the Lucas brand name is owned by at least two different companies making different parts and the electric and ignition parts at least are not made anywhere near the quality they were decades ago.  Despite the jokes about Lucas being "the Prince of Darkness" and bottles of "genuine Lucas smoke" the parts were made well and some are still on cars and working 50, 60, 70+ years later.  Some modern made copies and you are lucky to get 70 minutes use out of them, if that long.

 

I have probably mentioned this before, 😄, WD-40 is OK but better as a penetrating and longer lasting lubricant is GT85 with PTFE, if it is sold in your location.

 

If you have reasonably good quality tools then you can get away with using them on the brake unions but getting the correct sized flare nut spanner is a very good idea and takes some of the risk away.

 

I must admit if I was doing a complete brake system refresh I would now be very tempted to use (DOT 5) silicone brake fluid, a mate has had it in one of his - [ETA: "classic"] - cars that he restored and rebuilt himself 25 years ago and it has been fine, and he does not drive slow.

 

Good write up and photos, well done.

 

Edited 20 May, 20233 yr by nta16
ETA: reverse previous edit

2 hours ago, D.FYLAKTOS said:

Are made from Brass?

 

I removed 6 unions in total with this wrench. Its other side is no:10. I used number 10 for bleeding nipples of the front calipers. If you add that, I removed 8 critical parts that would be very expensive to replace if damaged from stripping.

We have months of salty roads here. So, effects of the corrosion is inevitable. I've faced "corrosion weld" before. It's a real menace.

I'm an average person and it took all of my power to release the flex hose connections at the rear and when they released, they released with a "bang".

When working on old cars, I think it's a good to choice to lower chance of failure whenever or however you can or DIY will turn into a nightmare.

 

1 hour ago, nta16 said:

Sorry but TWR is one of those companies I was writing about before, an old brand name no longer manufactured as in the past. Now part of  a company called ZF Aftermarket in the UK at least.  The quality of TWR brake parts was described as variable in 2017 (and later) at least.

I didn't know about that... In the parts market here, if something is from EU, it is considered superb.

 

1 hour ago, nta16 said:

As an example Lucas, a very famous UK company of the past, the Lucas brand name is owned by at least two different companies making different parts and the electric and ignition parts at least are not made anywhere near the quality they were decades ago.  Despite the jokes about Lucas being "the Prince of Darkness" and bottles of "genuine Lucas smoke" the parts were made well and some are still on cars and working 50, 60, 70+ years later.  Some modern made copies and you are lucky to get 70 minutes use out of them, if that long.

 

I think today's products are specially engineered for limited durability.

 

1 hour ago, nta16 said:

I have probably mentioned this before, 😄, WD-40 is OK but better as a penetrating and longer lasting lubricant is GT85 with PTFE, if it is sold in your location.

I checked its availability but it's not available locally. On the other hand, WD40 is like coca-cola.

 

1 hour ago, nta16 said:

I must admit if I was doing a complete brake system refresh I would now be very tempted to use (DOT 5) silicone brake fluid, a mate has had it in one of his cars that he restored and rebuilt himself 25 years ago and it has been fine, and he does not drive slow.

I didn't know if that is possible to switch to DOT5 with a system not designed for it.

 

1 hour ago, nta16 said:

Good write up and photos, well done.

Thanks for all the help.

 

I hope all of these will be useful for someone in the future.

1 hour ago, R_Blue said:

I didn't know if that is possible to switch to DOT5 with a system not designed for it.

 

I wouldn't take that risk, the Dot 5 must not mixed with Dot 4.

Can you "flush out" perfectly the whole system from Dot 4 before you turn to Dot 5?

 

I wouldn't make my Felicia as "test animal" just to save some money from brake fluids changes.

Is there a quarantee that your Dot 5 will last as long as you have your car?

 

I am saying that because i have heard about "lifetime" and "no need to change them" steering wheel fluids even for coolants.

 

1 hour ago, R_Blue said:

I didn't know about that... In the parts market here, if something is from EU, it is considered superb.

🤣  Some parts are very good, others good but others are not made to the same standard as previously, it depends on who bought the brands and what real interest they have in making a reasonably good product against the cheapest they can for the highest profit.

 

 

1 hour ago, R_Blue said:

I think today's products are specially engineered for limited durability.

Some of the parts, particularly those made in places like India or China can be abysmal, may not even work on initial installation, that's if they fit correctly.  If you compare some original parts with some modern made parts, especially if you open them up it is obvious why one part can last decades of use and another perhaps minutes of use, if not seconds.  That is not to say that India and China are not capable of making excellent quality parts but greedy European companies are not interested in that sort of business.

 

1 hour ago, R_Blue said:

I checked its availability but it's not available locally. On the other hand, WD40 is like coca-cola.

Shame as WD-40 Company own GT85, perhaps they only sell to UK because we know how good it is, same perhaps with Saint-Gobain reintroducing the old British brand of PlusGas and only selling it in the UK.

 

Any penetrating releasing fluid, even WD-40 Multi Use, is best applied thoroughly to a cleaned fixing and then if possible left to soak in for as long as possible, overnight or more is good, then if possible you try to first tighten to break any rust or crud seal before loosening, if does not work first time repeat the whole procedure.  If you have time and patience you can leave the chemicals to do the hard work for you and you do not need to be as thick in the arm as some mechanic (or head for some too).

 

1 hour ago, R_Blue said:

I didn't know if that is possible to switch to DOT5 with a system not designed for it.

 Sorry I was thinking of cars not as modern as yours with ABS, I will cross that bit through.

 

2 minutes ago, D.FYLAKTOS said:

 

I wouldn't take that risk, the Dot 5 must not mixed with Dot 4.

Can you "flush out" perfectly the whole system from Dot 4 before you turn to Dot 5?

 

I wouldn't make my Felicia as "test animal" just to save some money from brake fluids changes.

Is there a quarantee that your Dot 5 will last as long as you have your car?

 

I am saying that because i have heard about "lifetime" and "no need to change them" steering wheel fluids even for coolants.

 

You posted just before I pressed 'Submit reply' - see above post.

 

Just out of interest to you, I have read of someone who bought a 1950s and on doing a brake fluid change on it discovered car to find the previous owned had mixed DoT 4 and DoT 5, presumably by mistake, the new owner had been driving the car on very intermittent journeys for IIRC a couple of years and found the brakes to work fine.  As you say the two do not mix so when he changed the fluid it was easy for him to see the change in colour of the two fluids.

 

My mate put the silicone in his 1960s car over 20 years ago and said he has never touched it, I would probably flush it out with new every 10 years just in case there was any water trapped but he said he has had no problems and he deals with "classic" racing engines and cars every working day so has some experience and that is on top of owning and running a "classic" car as a daily driver and his "Sunday classic".

 

23 minutes ago, D.FYLAKTOS said:

I am saying that because i have heard about "lifetime" and "no need to change them" steering wheel fluids even for coolants.

There were "filled for life" gearboxes and such, of course the life they meant was to out of warranty or the engineers would expect the "life" to be a lot shorter than what a customer might expect.

 

You know I am all for changing gearbox and such oils even though many (including engineers) say it is not necessary or worthwhile but I have always found it worthwhile, as you did with the steering fluid.  In fact I would have changed the fluid twice by the time you changed it the first time so as we say here "you are preaching to the converted" with me. 😄  I've never heard of lifetime coolant but I used to use (Forlife) 4-LIFE coolant in a lot of my new and old cars but that had a stated life of 10 years.

 

2 hours ago, nta16 said:

Sorry I was thinking of cars not as modern as yours with ABS

 

I am not sure that @R_Blue has car with ABS

Model: Škoda Forman LX - W/LPG
Year: 1993

 

2 hours ago, nta16 said:

to find the previous owned had mixed DoT 4 and DoT 5, presumably by mistake,

As you say the two do not mix so when he changed the fluid it was easy for him to see the change in colour of the two fluids.

 

I have seen it in the Army, the previous driver (soldier) mixed Hydraulic oil (red colour) with other and the final result was something like beige.

Every NCO was pointed this to us plus everybody cursed that soldier for what he has done.

The door was working but it was a matter of time before they ''flush'' that mix and replace it wirh the proper (because everybody knows the concequenses if something is broke).

 

DOT 4, DOT4 racing, DOT5.1 yes but DOT5 for us here means ''Military'' mainly

 https://dot5brakefluid.com

and not every day use for moder cars.

 

1 hour ago, D.FYLAKTOS said:

I am not sure that @R_Blue has car with ABS

In that case silicone brake fluid could have been used, good to to add it when most of the components are apart and new empty parts added with the remaining parts cleaned and flushed out.  Though in reality as the two fluids do not mix so one will push the other out with flush changing after draining the existing, you just need to avoid any pockets of moisture being trapped in the system.

 

Its main advantage as far as I am concerned is that you do not need buckets of water and wet raags around in case any gets on to the paint.  Imagine fitting a TRW master cylinder to a freshly restored and painted engine bay and the seals go overnight spilling horrible cheap ancient technology DoT 4 all over lifting the paint.

 

Not having to change the fluid (or so often) is another advantage especially in what can be damp UK.

 

It is also better at heat and my mate said you can not tell any other difference, I have never driven a vehicle with it in that I can remember.

 

I think it is kinder(?) on seals too.

 

You can use it in ("classic") hydraulic clutch systems too.

 

Plenty of "classic" cars in the UK use it especially the restored ones that do not often turn a wheel. - https://www.moss-europe.co.uk/dynolite-silicone-brake-fluid-dot-5-946ml-ggl862110.html

 

13 hours ago, nta16 said:

Though in reality as the two fluids do not mix so one will push the other out with flush changing after draining the existing, you just need to avoid any pockets of moisture being trapped in the system.

 

Few months back i changed the brake fluid, one mechanic insisted that the systhem ''pump-start draw of old fluid-simultaneously add new fluid-after a while the whole system has the new fluid with no bubbles'' is ''new'' and ''better'' than other ways.

I never convinced that this kind of flow can remove any remains of air from all the system.

I said ''NO'' and i left, i went to another giving him strictly orders to do the change with ''Old fashion way'' which means 2 person, one is pressing many times the pedal and the other degassing etc.

I am not sure what new and better system you mean.

 

I used the one man (me) and a jar fluid sealed system and gravity or I pump pedal and fill reservoir if I want to go less slowly.  I've never had a problem, apart from the time I let the reservoir get too low but that was totally my fault.  I drain-flush double the system capacity, on brakes and clutch.  I have also help on the two man system with no problems.

 

But I have heard of others having problems with trapped air in brakes and clutch on the same model of car I had using two-man system and when using easi-bleed (a system I do not like) and other push drain systems.  I have never tried the bleed valve back to reservoir system.  And there are other methods of getting air bubbles out. I have not heard of problems with sucking out systems from top or bottom.

 

The suck it through from bottom to top sounds a good idea to me as air wants to go high.  The two-man system is pushing from top down which is against what the air wants for escape, but as I put I have never had a problem with one-man and a jar or two-man systems.  I think it is more a matter of what time and care is taken.

 

I always wonder about old fluid residue in ABS blocks but I have never done a change on one.

 

20 hours ago, nta16 said:

There were "filled for life" gearboxes and such,

I know a local gearbox specialist here only dealing with such gearboxes. Especially the automatic ones.

That shop is usually overflowing with cars waiting for the repairs. They drill those gearboxes from specific points to make them refillable.

 

18 hours ago, D.FYLAKTOS said:

I am not sure that @R_Blue has car with ABS

That's right.

There is nothing fancy.

No power steering, electric windows, ABS, A/C, airbag, ECU, sunroof.

 

16 hours ago, nta16 said:

Its main advantage as far as I am concerned is that you do not need buckets of water and wet raags around in case any gets on to the paint.  Imagine fitting a TRW master cylinder to a freshly restored and painted engine bay and the seals go overnight spilling horrible cheap ancient technology DoT 4 all over lifting the paint.

 

Not having to change the fluid (or so often) is another advantage especially in what can be damp UK.

 

It is also better at heat and my mate said you can not tell any other difference, I have never driven a vehicle with it in that I can remember.

 

I think it is kinder(?) on seals too.

 

You can use it in ("classic") hydraulic clutch systems too.

 

Plenty of "classic" cars in the UK use it especially the restored ones that do not often turn a wheel. - https://www.moss-europe.co.uk/dynolite-silicone-brake-fluid-dot-5-946ml-ggl862110.html

 

It has really good advantages over DOT4. I didn't know the seals were compatible with DOT5.

It's not hard to make a complete flush.

On the next fluid change, I will consider shifting to DOT5.

 

I would choose DOT5 just for the reason of being paint friendly.

3 hours ago, R_Blue said:

They drill those gearboxes from specific points to make them refillable.

Yes a much better idea but the car manufacturers did not care about cars that were old enough for the average person to think about changing the oil in a gearbox or those that might want to do preventative maintenance.

 

 

3 hours ago, R_Blue said:

No power steering, electric windows, ABS, A/C, airbag, ECU, sunroof.

Right.  That' is all good to me and much more what I am used to (other than perhaps having a droptop).

 

 

3 hours ago, R_Blue said:

I didn't know the seals were compatible with DOT5.

It is probably those people that have cars with worm seals that say you cannot use the silicone or those that do not do such thorough work at changes of fluids.  From my experience I guess It must either be worn seals or rubber hoses, or commination of both, that had your two year use brake fluid so black.

 

I often thought about changing to silicone fluid in the brakes and clutch but never got around to it as failures happened at inconvenient times and never coincided with service changes. 

 

6 hours ago, R_Blue said:

On the next fluid change, I will consider shifting to DOT5.

I would choose DOT5 just for the reason of being paint friendly.

 

Strenghts:

1) It has a high boiling point since it does not absorb water. Therefore, there's no so-called wet boiling point.

2) Doesn't absorb moisture.

3) Doesn't remove paint.

4) The viscosity is more stable over the extremes of temperature.

5) With the exception of some formulations used in external boots, silicone brake fluid is compatible with all standard brake components.

 

Drawbacks:

 

1) It's hard to pour without entraining air bubbles-hence an application will generally have a softer, spongier pedal feel.

2) It doesn't absorb water, so any water already in the system accu-mulates in the lowest point of the system and stays there, causing rust.

3) Glycol fluids begin to compress near their boiling points, whereas silicone fluids begin to compress at around 300-350 degrees Fahrenheit.

4) Additives in the fluid can vaporize at comparatively moderate temperature, increasing the spongy feel.

5) Silicone fluids expand significantly when hot.

6) Silicone fluid is functionally incompatible with systems that have held glycol-based fluids for any length of time, requiring flushing and seal replacement (there are counter opinions on this, which state that the modern silicone formulations are in fact compatible with only a flushing, rather than a complete reseal).

The actual DOT specification requires chemical compatibility, so as far as that goes, the two fluids won't cause reactions if used in the same system, but they certainly won't mix, either.

7) It's pretty much incompatible with anti-lock brakes because the silicone fluids tend to be more viscous, which can cause problems with the timing of the pulses that are intended to work with the thinner glycol-base fluid. This sometimes leads to damage of the ABS valving. The rapid pulsing necessary to anti-lock functions tend to cavitate the fluid, as the tiny bubbles collapse and coalesce into larger ones, and then collapse and reform into smaller ones. This tends to counteract the ABS effect and can diminish the actual effective braking. This condition also heats the fluid and can lead to even more sponginess and possible damage to the ABS controller. Thirdly, silicone brake fluid tends to foam when expressed from a small orifice under pressure, reducing its hydraulic effectiveness greatly.

 

https://www.jalopyjournal.com/forum/threads/whats-the-negative-of-silicone-dot-5-brake-fluid.185724/

7 hours ago, R_Blue said:

I didn't know the seals were compatible with DOT5

THEY ARE NOT

3 hours ago, D.FYLAKTOS said:

 

https://www.jalopyjournal.com/forum/threads/whats-the-negative-of-silicone-dot-5-brake-fluid.185724/

Interesting comments in that thread, some have very good experience of silicone over many decades and decades of use, others find problems quite soon.  One poster dared to suggest that those with problems at altitude might be due to driving technique or driver, I could not possibly comment on this.

 

As I put a mate's had, as far as I know, the same fill of silicone in his "classic" car for 20+ years with no issues and he is not a fool, liar or braggard.  Granted rubber seals might have been better quality 20+ years ago but it was only a few years later I was experiencing ****-poor rubbish rubber products and in car parts.

 

As with so many things if you do not agree with it, or believe, then that is fine each to their own.  I used to hear similar about certain oils, that they would damage the components, rot my teeth and ruin my looks, often from people who rarely drove their "classics" whereas mine we used as dailies for work, holidays and club events and tours.  I found no damage to any of the components in any of the cars in decades of use, I still have all my teeth (including a 'baby' tooth) and looks.  😄

 

But, as I put I've never used silicone brake fluid and I am not twisting anyone else's arm to either.

 

Edited 29 April, 20233 yr by nta16

3 hours ago, Thefeliciahacker said:

THEY ARE NOT

Why not?

 

 

Quote

If I were to switch to dot 5 I'd change all the rubber components in the brake system and flush all the steel lines and brake hoses.

 

https://www.corvetteforum.com/forums/c3-tech-performance/4724682-help-finding-seals-compatible-with-dot-5-brake-fluid-please.html

 

Selection of EPDM Elastomer in Brake Hose Application for Improved Brake System Performance

https://www.sae.org/publications/technical-papers/content/2010-01-1885/

 

Here is a ''study'' ,Rubber fluid compatability reference

https://www.parker.com/content/dam/Parker-com/Literature/O-Ring-Division-Literature/ORD-5700.pdf

 

I don't know if Model: Škoda Forman LX - W/LPG Year: 1993 has EPDM.

 

I could not find the EPA rule quoted - but I am not in America, nor are you so their rules do not apply to us.  However, the USA is fantastic for getting different answers to the same question and different opinions and beliefs so if you want to go round in circles with American web info try this (it is military so may be of even more interest to you). - https://apps.dtic.mil/sti/pdfs/AD1010795.pdf

 

I have no idea which if either, or both,  might be real or fake, it is the internet after all.

 

The DoT debate is very old as is what manufacturers want or need with what you use  - "The earlier U.S. version of D0T3 would destroy the natural rubber used in early Lockheed and Girling brakes from England.  Only Girling "Crimson" and Lockheed "genuine" fluids were usable, and they were hard to get in the US.  The later US D0T4 specification seemed to overcome this, as did the change to synthetic rubber for the seals.  CASTROL-LMA (Low Moisture Absorption) did better than most." 

 

I can from experience assure you that if the wrong type of seal is used with DoT 4 (or 3) then the seal will shred and break apart.

 

If a manufacturer advices against something it can be for many reasons but I would not blame anyone from following the manufacturer's advice/instruction, then you may find they change their minds later, as VW sometimes do.

 

On 30/04/2023 at 12:03, D.FYLAKTOS said:

I don't know if Model: Škoda Forman LX - W/LPG Year: 1993 has EPDM.

That would only matter if the factory fitted parts are still fitted to the car, if parts have been replaced then it depends on the replacement part. 

 

With these types of issues when all things are equal most often it is by far best to do whatever you will be most comfortable with.

 

Edited 20 May, 20233 yr by nta16
spelling

2 hours ago, nta16 said:

but I am not in America, nor are you so their rules do not apply to us.

 

So let's read what the Mini Cooper drivers (not Americans) say about it:

 

https://www.theminiforum.co.uk/forums/topic/275028-dot-5-brake-fluid/

 

Among them:

 

Quote

I used DOT 5 in several high mileage cars, after a full brake system overhaul, replacing all seals, hoses (Goodridge, cheaper than OEM in some cases) and pipes (Kunifer of course, NEVER copper), and they went on to achieve very high mileages, up to 200k, without further attention to the brakes, except routine pad, and occasionally disc, changes. The fluid remained clean, and did not need to be changed.

However, none of these cars was a Mini, and although I have had 3 Minis and must have flushed and bled the brake systems many times, including full seal and hose replacements on 2 of them, and never had the slightest difficulty in bleeding any of them, there are many sad tales on this forum of people who can't get them to bleed (may depend on brake system configuration), and for that reason I would suggest that the use of DOT 5 in a Mini is strictly for experts, or those with a reliable method, such as a suction bleeder, of getting the air out.

 

Quote

I have seen the same warranty statements for new TRW manufactured cylinders and similar warnings from two shops that sleeve old cylinders for antique cars.  When I inquired about "why", in both cases I was told it had to do with the lubricity of the DOT-5 fluid preventing the seals from operating as they do with DOT-3 and -4.  The firms took the position that DOT-5 required different surface finishes in the bore to work properly.  When your product involves safety items you certainly would want to protect yourself from any liability issues by not endorsing the use of alternate brake fluid.

 

As put previously

 

On 28/04/2023 at 11:44, nta16 said:

Sorry but TWR is one of those companies I was writing about before, an old brand name no longer manufactured as in the past. Now part of  a company called ZF Aftermarket in the UK at least.  The quality of TWR brake parts was described as variable in 2017 (and later) at least.

 

Let us agree that you could be right and I am, or could be, wrong.