TR2/3/3A No braaaakes!

[STeve 1958]

Drove the 3 all weekend actually going places as opposed to just test drives. About noon Sunday I hit the brakes and they went to the floor.
One pump and I had brakes again. I limped home and did a quick (5 minute) bleed of the front brakes and it firmed right up again.
Drives great.
Now I need to do a complete bleed. Should I use the cans of dot 4 brake fluid that came with the car. I assume that's what's in it now.

 

[LarryK]

I only use DOT 4 Castrol. DOT 3 is not compatible with rubber inners of British brakes.

 

[CJD]

I assume it’s a disk brake “3”? If it sucks air again, you may have excessive runout on the front brake discs. If the runout shows true, then the master cylinder piston seal may be going.

 

[TR3driver]

Should I use the cans of dot 4 brake fluid that came with the car. I assume that's what's in it now.

Is it still factory sealed? If not, it's trash.

Conventional brake fluid fails mostly by sucking water out of the air (known as being hygroscopic). That process starts when the can is opened, and continues even after it's resealed.

If you actually found air in the lines, I would want to have the MC apart to check both of the springs in there. They can break and cause some very strange symptoms, especially if the little valve at the bottom of the bore doesn't always open when you release the pedal.

If you didn't find air, check the residual pressure valve on top of the 5-way connector. It's there mostly to deal with the case where the front spindles flex in a hard turn, but also reduces the effect of rotor runout, loose wheel bearings and so on.

BTW, the instructions in the workshop manual for adjusting front wheel bearings are wrong for cars with front disc brakes. Should be 1/2 flat clearance rather than the 1.5 to 2 flats given in the manual.

 

[sp53]

Wow lucky man that could have been a genuine bummer. I had that happen in 1950 chev ½ ton truck and they did not come back, finally stopped by doing donuts. The e-brake did not cut it. If you still had brake fluid in the system, I would buy a new master cylinder and try that.

 

[STeve 1958]

Thanks all. Yes, the dot 4 can was sealed so it's ok
This car has a sordid history so I don't know how old the fluid is. I'll replace it all this week and see how it goes.
The brakes have always been soft, first thing in the morning, which is common. However they always pumped right up and stayed firm.

Have a TR-iffic day!

 

[Andrew Mace]

The brakes have always been soft, first thing in the morning, which is common. However they always pumped right up and stayed firm...

No offense, but that is an issue I'd have addressed before any serious driving! And while I was doing that, I'd also have made sure all was well with the emergency brake. I know from long-ago personal experience that a TR3 "emergency" brake can pretty much live up to its name!