soft brakes

[Jfornachon]

I rebuilt the master, and calipers. I also replaced both wheel cyls. I then put every back and bled the brakes. Now I have a spongy pedal. Did I do something wrong.

Have a greatfull day.

[jclay (RIP 2018)]

The brakes are really hard to bleed. Did you bench bleed the master cylinder?

You can check this link to double check your work. http://web.mac.com/jclaythompson/iWeb/Site/Rear%20Brakes.html

It is really hard to get all of the air out of the rear brakes. Did you remember not to put the brake fault light indicator switch in under the master cylinder until you had totally bleed the brakes?

[Hasbeen]

My experience, with 4 different 7s, is that it takes some driving to
get that last bit of air out of the brakes.

After you get to that spongy, but not too bad stage, a 15 Km drive,
& another bleed gives a big improvement. However, its only after
another 50Km of driving & yet another bleed that the last of the
air is gone.

I used to blame the rear piping for this charasteristic, until I
fitted discs on the rear of the 8. With discs, a Volvo master
cylinder & normal piping, joined in the center of the diff, I still
had to follow the above procedure to get a solid pedal.

I now blame the presure reducing valve, as its the only Triumph bit
left, in the whole system. [Volvo 4 pot front calipers]

Obviously, it could not have anything to do with my bleeding
technique, could it?

Hasbeen

[Periwinkle]

Jfornachon,

If the brake bleeds do not eliminate the problem, check the servo unit. Mine went bad over the summer and periodically I'd lose pedal and stopping ability. I replaced the unit last month.

Good Luck.

Peri

[john 215]

Hi,
If you clamp each flex hose at a time,using the correct type of hose clamp and providing you have'nt got braided hoses,does the pedal travel improve when one particular one clamped? If so there is where your air is. Another trick that sometimes work is leave pedal wedged down overnight at least,this allows trapped air back through master cylinder.
If you have installed new discs and pads then you will have poor brakes for a couple of hundred miles whilst they 'bed' in.
Cheers John.

LIVE LIFE A QUARTER OF A MILE AT A TIME!
1979 3.5 FHC(STATUS PENDING!!)
1982 2.0 DHC Soon to be a 4.6 fire breather!!
Read My Blog http://www.waringstowntr7s.co.uk/blogs/ ... hp/John215

[dbutterw]

Agree with John all new Brake parts take a little while to bed in then re adjust those supposed auto adjusters on the rear brakes, (manual adjust until a little drag) Also so far as bleeding is concered, try a pressure bleed system,(rather than the manual way) in the UK there is a product called Ezzey bleed. It works by using pressure from a spare tyre,(under £20) it allows you to bleed the brakes without and assistant and forces air out of the system. There are many other products avaiable which do the same job.

TR7 4.2 V8 Drop head (Java Black)
1972 Mini Clubman (British Racing Green)

[fastman]

Question for Hasbeen.

I'm rebuilding a TR8 FHC and curious about your brake set-up. What Volvo car did you use? Was there much adapting? Disks? So far I've purchased the steel braided lines and a set of 15" alloys. I'm open to ideas. Us Canucks have Volvos aplenty here. (also a volvo devotee neighbour)

[Hasbeen]

Sorry fastman, I don't know.
The front brakes were a kit from Triumph Rover Spares, in Adelaide
South Australia, & they don't tell. The same setup is used on many
7/V8s conversions, in Oz.

Hopefully Jolyon will pop up, & tell you. He has researched all this
stuff, & realy knows whats what.

If he doesn't, drop him an e mail, he loves talking about 8s, & I'm
sure he will be helpfull. He dropped in here to have a look at our
Skyline diff installation, when he was in Os a while back, & knew
more about our car, than I did.

Hasbeen

[stever_sl]

Some people say the silicone brake fluids can produce a soft pedal even when everything's adequately bled. If you used that kind of fluid, maybe that's it? I've never used anything but DOT 3 myself so I don't know, I'm just passing on what I've heard. Opinions seem to run VERY strong on DOT 3/4/5 among hardcore car enthusiasts.

- Steve Richardson
St Louis MO

[adurand]

After we obtained a new master cylinder for our brake system, we bled everything with synthetic brake fluid. As many people have said on here, it takes a bit of bleading to get all of the air out, but I don't believe the synthetic altered the pedal feel (other than having air in the pipes to begin with).

In other words, I think both synthetic fluid and normal dot3 have the same feel, but either way it takes time to get the air out of whichever you use. Possibly the people who have felt that synthetic fluid is more spongy have not gotten all of the air out of the system. Who knows though, I'll have more to say once we actually have it on the road for a few thousand miles, it's currently awaiting more bodywork and a paint job before it goes on the road.

[Jolyon39]

Fastman, here is what I know about the Volvo option.

Master Cylinder:

Can not suggest which master cylinder to use but logic suggests that you use the one off the car that donated its callipers. I am told that you need need a master cylinder with a bigger swept area to move the extra brake fluid needed for the 4 pots. Mk1 SD1 Rover seems to be good and keeps your car looking original...sort of.

Callipers:

Volvo 240/260 callipers (Australian Models) - two types on these cars, Girling (22mm Disc's, 1976 to 1993 model cars) and ATE (24mm Disc's, 1975 to 1993 model cars) use the ATE Callipers. Calliper mounts have to be modified by drilling the bolt holes slightly wider to fit the TR (Plug and then drill). Convert the dual pipe inlet to single by either cross drilling or use this EXCELLENT kit:

http://www.mildevco.net/chevypowereddat ... brakes.htm

The rotor used by Triumph Rover Spares in South Australia is Part Number DBA-631-MB 19/6/96-MINTH 18MM-2N. (DBA = Disc Brakes Australia) This vented rotor is found on Ford Courier/Raider 1985 -1995 models with 1.8, 2.0. 2.2 and 2.6 2WD motors. Also On Ford Econovan/Spectron 1984 - 1992 with 1.8, 2.0. 2.2 motors in STD and LWB chassis. The standard TR rotors are 240mm in dia and these are 256mm in diameter, they work with the new callipers.

You need to make up a bell to mate the new rotor to the calliper.


Piston Diameter stuff:

Here is part of a spread sheet I have made up covering piston diameters. First column is the calliper known by the car we take it from, second is the dia of each piston, third is the number of pistons and final is the culmulative total of piston surface area in mm2 used to exert force in a calliper.

TR7 51 2 4086
TR8 54 2 4580

Princess 38 4 4536
Volvo 38 4 4536
Capri 54 2 4580
Hi Spec Motor Sport Ver 1 38.6 4 4681
Hi Spec Motor Sport Ver 3 41 4 5281
Vitesse 41 4 5281

NB: Note that Volvo is pretty much the same as a genuine TR8 calliper.

This of course does not take into account the extra leverage you get when you stop a 256mm dia rotor versus the 240mm rotor. The radius or leverage is longer therefore more force is exerted that way as well. I am not an engineer and would enjoy someone adding precise maths toall this data.



Yes, I love talking about 8's Hasbeen.....does it really show that much.... Chuckle.

[Beans]

Also have a look at your flex hoses (if they are of the rubber type)


<center>
<font color="blue"><i>1981 TR7 FHC Sprint (better known as 't Kreng)
1981 TR7 DHC (not very well known yet, but back on the road)
Also a 1980 TR7 DHC, 1980 TR7 DHC FI, 1981 TR7 FHC
http://tr7beans.blogspot.com/</i></font id="blue"></center>

[bmcecosse]

Just a suggestion - something that seems to catch out Mini owners quite often - - have you put the calipers on right way up - with the bleed nipples at the top ?

[fastman]

Thanks Jolyon. I've already checked into the archived post regarding the volvo calipers which you had discussed in the past. I think the conversion will happen once I allow the information to steep a bit (things seem to go better for me that way). Perhaps I will try the original brakes for the first season before 'tweaking'. Either way I still have time as the car goes for paint next week.

[Hasbeen]

Fastman, my 7 has completely stock brakes, apart from green stuff
pads. I carefully overhauled them, 5 years ago, when I restored the
car. I have always found them totally adequate, although no match
for the brakes on the 8.

I have only had them fade on me once, & then only slightly. That
was when I decided to show a rather annoying bloke in an ultra
modern, 4WD rice burner, 4 door, "sports car" that it was more about
the loose nut behind the steering wheel, than the fancy electronics,
& suspensions, when it came to getting a car down a mountain,
quickly.

He was last seen, parked against the safty fence, with his "lady?"
passenger belting into him, & I think, screaming at him. I
wonder if she now prefers old, 2 door sports cars?

I did stop at the bottom of the hill, to let my brakes have a quite
smoke. I was going to wave at the rice burner when it appeared, but
it didn't.

Now, after over 40,000 Km, I have twice locked a front wheel, in
wet, greasy conditions. They do not lock as often as our new rice
burner Mazda's do, in the same conditions. Those are far too over
boosted for an old bloke, used to old trucks, & tractors.

Inspection has shown some wear, & slight grooving in the discs,
which were not replaced, back then, so I guess its now time to
replace them.

What a long winded way of saying, that for normal road use, I
believe the stock brakes, in good condition, are fine. If you want
to drive the car realy hard, as we do with the 8, fit the upgrades.

Hasbeen

PS. Thanks Jolyon.
H