Brake fluid for Triumph TR7

[mmarks]

Having had seeping rear cylinders I now have replacements & new shoes.

I will need to top up my brake fluid after. The haynes manual states universal brake and clutch fluid, is this the same as DOT3 or DOT4 or DOT5 or is it something entirely different?

[TR Tony]

If you don't know how long the brake fluid has been in there it may be a good time to flush through & replace with new.

I don't think you can get DOT3 these days? Basically your choice is between DOT4 conventional glycol based fluid or DOT5 silicone based fluid.

Some people advise against DOT5 because it does not absorb moisture & hence there is concern that any moisture that does get into your brake system will just sit there & may corrode the internals. On the other hand many people like DOT5 for exactly the same reason - it it not hygroscopic & has a higher boiling point than conventional DOT4, & because it will not absorb water DOT5 also can be left in the system for longer. Also, it will not damage paintwork if spilt or if yuo have a leak. I must say I have it in both my cars & have had no problems.

Don't confuse DOT5 with DOT5.1 - 5.1 is also glcol based, not silicone, but is usually intended for hard used brakes or race conditions.

If you change from one to the other flush the system thoroughly - the two types dont mix!

Tony

[bmcecosse]

If you change to DOT5 silicone fluid - you MUST change every seal in the system, or they will react with the new fluid and swell up causing chaos. Best to stick to DOT 3 or 4. And yes - good idea to flush the whole system through with new fluid.

[saabfast]

Its not difficult if you use a pressure bleeder (Gunsons Eezi-bleed or similar). Just pressurise and open the nipples in turn - dont forget to remove the switch from the bottom of the master cylinder first. Fronts are OK but it normally takes 2 or 3 bleeds to get all the air out of the single rear nipple. Helps if you leave it running out for a few extra secs after it runs clear to drive the air through.

Alan
Saab 9000 Stg 1
'81 TR7 DHC

[bmcecosse]

I changed the seals on a rear cylinder earlier this year - the brakes bled out by gravity while I enjoyed a cup of coffee. Pipe on nipple and into jam jar with a little fluid - open nipple, drink coffee, top up reservoir, finish coffee, close nipple and remove pipe etc -and final check on reservoir level! I also changed a font flexi pipe by the same method - perfect pedal both times.

[konnie]

hope to be fitting front brakes in next week or so, question is as in prevous post by saabfast, remember to remove switch below master cylinder before bleeding brakes, what switch, what does it do, why do you have to remove it,what does it look like, also disc brake dust shields do you really need them as the worms have ate mine. thanks

[flynns tr 7]

Dont forget if you are bleeding the brakes to take out the pressure differential switch in the master cylinderif you are pumping the pedal.Their is a possibility the piston can snap off the switch and you will have the brake light on the dash permenatley stuck on and possible damage to the internals of the master cylinder.

[bmcecosse]

But if you do 'gravity' bleeding there is no risk! Disc shields - not necessary, although they help to keep water off the disc, so just remember to press the pedal lightly after passing through any deep puddles! Although to be honest - I feel centrifugal force will soon clear any water off the discs anyway!

[saabfast]

Konnie, in the underside of the master cylinder there is a white plastic switch, screwed into the body with a cable connection plugged on. This indicates 'brake failure' via a light in the instrument panel (loss of pressure in one side moves the secondary piston and allows the pin on the switch to 'make', I think). This needs to be removed for conventional bleeding pumping the pedal. Not sure about when using a pressure bleeder but I do it anyway in case. The switch needs a little care in removal as it can shear off and the bit left in is very difficult to remove without taking out the master cylinder.

Alan
Saab 9000 Stg 1
'81 TR7 DHC

[konnie]

thanks for the advice,found the said switch but not in bottom of master cylinder,it was stuffed down under a bit of wireing loom next to bulkhead covered in dust, must have been removed by previous owner for some reason no doubt will find out why shortly, thanks again for your help, wullie.

[Middle7]

Hello,

Does anyone have any tips/advice for bleeding the rear brake circuit. I have tried a vacuum bleeder and a Gunson's Eezi-Bleed, without success. Not a drop of brake fluid emerges from the nipple. The nipple isn't blocked. I have taken the nipple right out and no brake fluid has emerged from the hole. I suspect that the pressure reducing valve is causing problems. Fronts bled out ok.

Over the years I have bled many systems and the Eezi-Bled has never failed. I am a bit stuck and don't want to use the two man method as I reckon this can cause damage to the seals in the master cylinder when the piston travels past its normal use position.

[tr7jim]

Middle7,

I have similar problem with no fluid comming out and found out the cause was the flexiable hose had clapsed so try undoing the couple after the hose to see if this is the case or not.

Hope this helps

Jim

[Beans]

You might be corect there, they do have a tendency to fail with old age.

But also check if there isn't a blockage in one of the rear cylinders (might be rusted up badly)

[Rich in Vancouver]

Whatever you do don't use the Eezi-bleed at more than the recommended pressure. Yes, check the pressure in the tire you are using even if it means rummaging around in the other car to find the gauge.

It seems that 25psi is enough to blow the top off the brake master cylinder and send a geyser of brake fluid over every painted surface of the car.

Don't ask me how I know this!

Cheers,
Rich

I second checking the hose.

1975 TR7 ACL764U

[FI Spyder]

Concur, rear hose might have swollen shut. If your concerned with master seals wearing on sections of master cylinder that might be corroded you can place a piece of 2x4 under the brake pedal so it doesn't travel full distance, however if it is in that condition master brake cyinder should be rebuilt. Never had a problem with two man bleeding as I change fluid regularly (it's cheap). For one man I use a one way valve in container thingy I picked up from Princess Auto FOR $5.00. Works like a darn. Don't need any fancey pressure bleeders.



TR7 Spider - 1978 Spifire - 1976 Spitfire - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra