Lockheed 329?

74 MKIIA Commando

Hi gents,

Tried to look this one up, but I didn't come to any conclusions.

Shop manual says use Lockheed 329 for brake fluid. Went to a bike shop, they didn't have any, so one of the parts guys googled it
and said it would be okay to use Dot 4. (Bel Ray Super Dot 4)
I went to fill up the MC and the cap states " use Dot 3 ONLY "

I'm starting from scratch with a rebuilt MC, and just do recreational riding.

Is it OK to use the Dot 4?

Appreciate your thoughts.

Chester said:

I went to fill up the MC and the cap states " use Dot 3 ONLY "

Is it OK to use the Dot 4?

Click to expand...

That original "DOT 3 ONLY" recommendation is 40 years old.

DOT 4 fluid has a higher boiling point than DOT 3. DOT 4 is OK to use where a DOT 3 fluid was originally specified. I have used DOT 4 fluid for many years now.

http://www.american-auto-club.co.uk/aac ... show&id=70
http://en.wikipedia.org/wiki/DOT_3

any experience with dot 5?

alexhobo said:

any experience with dot 5?

Click to expand...

Yes. Great for racing, NON hygroscopic. I left it for a long time in a street bike I bought new, turns out it corroded the brake system just like conventional (DOT 4) fluid. Not needed for street use. Use conventional DOT 4 (which has superceded DOT 3) and change every 2 years. Be happy.

the dot 5 is NOT good for racing as it has several issues, one of them is it can get air bubbles ( boil) where it passes through an orifice. I had to remove it from my bike as it would get air in it from hard mountain rides.

concours said:

alexhobo said:

any experience with dot 5?

Click to expand...

Yes. Great for racing, NON hygroscopic. I left it for a long time in a street bike I bought new, turns out it corroded the brake system just like conventional (DOT 4) fluid. Not needed for street use. Use conventional DOT 4 (which has superceded DOT 3) and change every 2 years. Be happy.

Click to expand...

Thanks for the info guys. I'm going to go ahead and use the Dot 4.
I wish I had mountains and curves to ride in, but it's just flat-a** prairie.

Cheers

Here's recent scope on brake fluid and issues with a few not covered yet.

post161677.html?hilit=Dot%203%204%205#p161677

Main info I was relieved by was DOT 3 &4 4 are comparable to mix and Lockheed parts are comparable with every DOT. The main market for type 5 is those that store for years of no use at a time, like military and museum. DOT5 is not hygroscopic, which ONLY has a benefit to not rust up as fast but make no mistake condensation can still collect over time to settle in a puddle and oxidize what ever it can. DOT 5 is compressible enough racers don't use it. I'd sure like to hear from those that notice fade from over heating DOT 3 by repeated hard use in hi summer.

Serious braking is my worse nightmare. After I fixed lever end heat leak out m/c piston couple weeks ago I forced me to test it over an hour in steeps till I got scary fade, but only, after 4 hard squeal downs. I assumed that may of been air adhered to hose still working its way out. I felt caliper - too hot to leave finger on for .5 sec. My recoil finger temp senor calibration implies ~175'F' on caliper and over boiling on rotor. This fade suddenly prevented any squealing no matter white knuckled grip, but squeal ease returned after15-20 sec w/o brake use. Air bubbles heat expanding, residual moisture boiling or fluid vaporizing?? Friction surfaces are good as instant squeal to lock up on first harsh grips, so why the fade?

I've ridden a number of times since and tested to scary squeals w/o any fade, but not in strong enough emotional test state beyond just making sure it'd work fine on normal use and a one in a row panic grip. No air should remain by now so still have questions to settle - can I tell a difference in factory brake boiling temps of DOT 3 or 4? Wes and I want to try a track day so that may be where I find out. I await some others testing reports as I've not enough experience yet to know which to settle on buying with least worry.

thanks, when my master cylinder and caliper were been rebuilt i went to dot 5. Shortly after, i started getting drag that becomes progressively worse, ive flushed it thinking moisture got in the line-didnt help. it was suggested to me that i may need to replace the line. thoughts?

Searching my memory banks, all I remember from my days in the trade is advising my customers to never use Dot 5 on anything unless it's specifically called for.
I recall that it's silicon-based, and can attack 'standard' brake components, but I've no specific experience as I've never used the stuff!