Brake pedal travel....

[Sean Roth]

So I rebuilt the front calipers, put on new rear shoes and pistons/hardware.
My brakes work fine, but there still seems to be a lot of travel on the brake pedal until I feel pressure. More than my other cars at least. I have never driven another TR7 so I can't compare it to another one.

There are no leaks in the system, checked while under pressure a bunch of times and the pedal never gers soft once I hold pressure to it.

Is there an adjustment I am missing? I would guess that the brake pedal goes half way down until I feel pressure.

When the engine is off the pedal gets pressure at a normal position, but once I turn the engine on and the booster activates then the pedal goes down further.

Thanks,

Sean

SF Roth

[busheytrader]

Are your calipers the std items? Uprated calipers have a larger swept volume and require more pedal travel from the std master cylinder.

Are the automatic adjusters in the rear drum brakes correctly set up and working properly? Its quite easy for them to seize up from rust and / or brake dust. It could mean the shoes are being held too far away from the drum's surface when your foot's off the brakes.

Adam





TR7 V8 DHC Jaguar Solent Blue. 9.35cr Range Rover V8, Holley 390cfm, JWR Dual Port, 214 Cam, Lumention, Tubular Manifolds, S/S Single Pipe Exh, 3.08 Rear, 200lb Spax & PolyBushes all round, Anti- Dive, Strut-Top Roller Bearings, Capri Vented Discs & Calipers, Braided Hoses, 4 Speed Rear Cylinders, Uprated Master Cylinder & Servo, AT 14" 5 Spokes or Maestro Turbo 15" Alloys, Cruise Lights, S/S Heater Pipes, Replacement Fuel Tank. No Door Stickers. Mine since July 1986, V8 from 1991 courtesy of S&S V8 conversion and big brake kits.

[Workshop Help]

Compared with most other cars, the pedal travel on a TR7 is different. You might try adjusting the rear brake shoes closer to the drum, but this will not significantly alter the situation. The issue lies in the brake booster itself and the travel of the diaphragm to effect the braking action. A new/rebuilt booster will not be appreciably better.

Mildred Hargis

[Hasbeen]

When the self adjusters on one of my 7s rear brakes stopped working, the pedal travel increased very rapidly. After pulling the thing apart, polishing [just with a wire brush in the drill] all the parts of the adjusters & the shoes rubbed on each other, & lubricating with graphite powder, they returned to normal, with little travel.

Another member had a problem with long pedal travel after rebuilding his brakes. He ultimately found that the shoes, after relining, went back in different places. One had a dag of welding spatter, from the original manufacture, & it was now right where the self adjusters had to slide, making them stick.

Once the dag was removed, & the above polishing done his brakes worked properly again.

Does partially applying the handbrake while driving make any difference to your pedal travel?

Hasbeen

[Vino79TR7]

Sean:

After replacing my pads on shoes I had a similar sounding problem…it turned out to be the brake booster.

Here’s the simple test…While the car is turned off, have someone step on the brake, then release…step on the brake, then release…keep doing that. Meanwhile spray some soapy water (anything that will foam) on the master cylinder where it’s attached to the brake booster. If bubbles appear, the brake booster is bad.
-V

[Graham.Fountain]

Another quick test of the servo (courtesy of Paul Towle) is to put your foot on the brake pedal with the engine off and then start it. The pedal should fall significantly as the engine starts, if the servo is working at all.

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