Brake fluid for 1967 Mark 111

[forest]

Hello all
I have a 1967 3 litre Mark 111. Unfortunately I do not have the proper owner's manual; I downloaded from the New Zealand Club's website the manual for the Mark 11. It specifies as brake fluid "Crimson" "as the only fluid which should be used in these brakes". In case of emergency," a fluid complying with the SAE 70 R 3 specification".
Just what is the "Crimson" brake fluid? I never heard of it. Was this specification applying to Mark 111 models? What are you using? DOT4?
Roverly yours
Forest

[dorsetflyer]

I think 'crimson' referred to either Lockheed or Girling brake fluid and it was a reddish colour similar to ATF, it would have been used extensively throughout all vehicles of that time, not just Rovers.
Obviously since those days brake fluid has been improved over the years and for these cars nowadays 'DOT4' is the most common.
Even the seal materials would not be the exact same as those back in the sixties/seventies.
I believe DOT5 is a fully synthetic fluid and shouldn't be used in classic cars, unless the whole braking system is updated with the latest materials.

[Phil Nottingham]

It may have been reddish but it was not like ATF - any modern brake fluid will do and its best to flush/renew it all anyway

[forest]

Thanks for the replies. Would DOT 3 do the trick? I tried to find mineral DOT 4 today, but could only find synthetic DOT 4, and although opinions seem to be varied on this, I gathered from what I read on this forum that using synthetic was at best useless and at worst nocious. Mineral DOT 3 is more common here where I am and of course easy to find and cheap.

[enigmas]

Forest, your first few comments lead me to believe that you are new to the wonderful world of restoration and perhaps mechanical repair of older vehicles. Mineral oil based brake fluid over time absorbs moisture (its hygroscopic) hence the rust that develops in the system. Brake fluid is meant to be changed on a regular basis (say every 2 years) but no-one really bothers. The internal seals all have a limited life span before they start to weep and eventually fail. On an old car of unknown history and one that relies on a single circuit I'd be replacing at a bare minimum the master cyl and rear wheel slave cyl seals. I've never yet seen the front caliper seals weep (someone will correct me on this, I'm sure) and if it were my vehicle I'd do them all. I'd stick with the highest spec mineral oil based brake fluid that you can get (from any decent auto parts store). As Phil advised purchase several bottles and pump fluid through each wheel bleed screw and the power brake unit until only clean fluid exits the bleed nipple.

[Phil Nottingham]

DOT 3 perfectly Ok - in fact its difficult to get hold of over here now as it all Dot 4 but as long as it new it is far better spec than Girling Crimson.

As to caliper seals the piston seizes up before they leak and I have never had one blow. It did damage a new one once fitting it and that leaked!

[stantondavies]

I thought that the main difference between say DOT4 and DOT5 was the higher boiling point the fluid.

[enigmas]

Here, read this tech link.
www.xs11.com/tips/maintenance/maint1.shtml

[Warwick]

Aug 14, 2008 11:55:36 GMT enigmas said:

I've never yet seen the front caliper seals weep (someone will correct me on this, I'm sure).

I'll send you some photos Vince. That was one of the reasons it failed the roadworthy after the drive home from Brisbane.

Thanks for the brake fluid article Vince. I haven't seen one with this level of explanation before. I was disappointed though to find it a fairly straight read.
When I saw the title "DOT 3-4 Verses DOT 5", I thought it was going to be a poem or perhaps a passage from the Old Testament.

[Phil Nottingham]

It is the main difference - but there are some scaremongers at work, these have vested interested in getting old cars off the road