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Hi all

 

I've uprated the brakes on my daughter's '7', but for some reason I can't bleed the system.

It has EBC discs and greenstuff pads up front and uprated shoes at the back.

I fitted new copper pipes and stainless braided hoses and to finish off have also fitted a master cylinder and servo from a Sherpa van.

The problem is that when I try to bleed the brakes the fluid doesn't pump into the system, I just get some air and a few dribbles of fluid and that's it.

Ive removed the two pipes from the brake pressure reduction valve and expected to see fluid pump out when pressing the brake pedal, but nothing.

I've removed and stripped the master cylinder again to check that I had rebuilt it correctly, but all is fine.

I can even pump air through the master cylinder apertures and all seems ok so now I'm running out of ideas and the mot is booked for tomorrow.

I bought the master cylinder and servo as a matched pair form a Sherpa breakers and it has all new seals fitted.

 

Any ideas?

 

Regards

Lee

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I understand that this upgrade is not a straight forward 'plug and play'. You need to change the length of the servo's input shaft so that the clevis fork reaches your brake pedal and also reduce the length of the push rod that connects it to the brake pedal as the Sherpa unit is too long. I am afraid I am no expert on this upgrade but I suggest you speak to Steve @ S&S who might be able to advise...

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  • 2 weeks later...

Thanks for the feedback.

I spoke to both S&S and Robsport and there is no modification needed, the unit bolts straight in.

I have moved on from there as I may have a problem with the master cylinder so I have refitted the original TR7 master cylinder and servo.

After a lot of grief I have managed to bleed the system and have good pressure on the pedal when pressed.

The problem now is that when I start the engine the brake pedal goes halfway without any pressure and then the brakes bite. Surely there should be less travel with the aid of the servo.

I have tested the pressure balance unit, re-bled the system (there is no air coming through) and checked the one way valve on the servo.

Any ideas as my daughter is desperate to take it to CLM in 2 weeks.

 

Regards

Lee

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Hello Lee

 

I believe my brake pedal travels further when depresed with the same foot force when the engine is running as you have additional pressure applied by the servo which is coming into operation..

I consider this normal.

The inability to bleed the system i.e.take in fresh fluid sounds a problem of insufficient free travel/clearance either with servo to /m/c push rop or pedal push rod and m/c. This may well not allow the m/c piston to fully return to a position which would allow entry of fresh fluid.

I think I would operate the m/c independently on its own off the servo to see if it operates correctly.

Check the piston returns fully and then move the piston with a blunt screwdiver.

Watch out for mess!

Good luck.

David

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I believe the problem we have bleeding our brakes is in the distribution valve. This is only by deduction, but it is sound deduction.

 

I have owned a number of 7s some with stock brakes & some uprated, & an 8 with highly up rated brakes. I was a brake, hydraulics, & suspension specialists for years, so have some experience. I have never been able to get any system on a 7/8 bleed in one go. It always takes 2 or 3 goes, with some miles between bleeds to get them where I'm happy.

 

This has applied to 2 7s with stock, fully overhauled systems, with up rated pads.

 

It has applied to 2 with Volvo Front calipers, master & servo, with stock rear drums, & to the 8, with the Volvo master booster & front rotors & calipers, with Nissan Skyline rear discs & calipers. With this last car, the 8, the only Triumph bits are the distribution valve & the brake line to rear.

 

I keep threatening to pull one of the things apart, & sort it out.

 

If this threat ever becomes something other than an idle threat, I will post my findings.

 

Meanwhile I am about to do the third bleed on my 7s brakes, having had to release the rear hose during a fuel tank replacement.

 

 

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  • 2 weeks later...

Thanks guys for the info.

My daughter and her boyfriend successfuly got to Le Mans and back and the brakes were fine apart from the long travel.

I'll have another go at bleeding them now the car has got some miles on it.

The car hadn't turned a wheel since 2003, was only driven about 15 miles the night before the trip and the only issues were a loose fan belt, a slight shunt up the back by another group member at a set of lights (no damage to the '7') and the viscous fan and coupling coming adrift at 110kph on the motorway run back to the ferry.

Luckily it damaged the radiator, but didn't puncture it so we managed to coax the old girl home.

An electric fan will be fitted.

What a baptism for all concerned including the '7'.

 

Lee

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Hi Lee,

 

Great the car got there and back, almost trouble free.

 

When i was running shoes and drums on my 7, i installed a 'T' piece on the rear so each wheel cylinder had its own nipple,

 

Also can help if you wedge the pedal down overnight, this can allow trapped air back out of the system

 

 

STA70375.jpg

 

 

Are using DOT4 or DOT5 fluid, have heard from several people that they get slightly longer travel with DOT5 ( although most seam to have no problem ! )

 

Cheers John

Edited by john 215
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Having major headaches with brake blleeding too. Fitted Goodrich hoses to front calipers which are Vittese 4 pot with vented discs and 4 speed rear cylinders. Have properly bled all four corners and had some pressure on the pedal albeit still travelling to the floor but when the engine starts what little resistance there is vanishes. Am considering a sherpa servo upgrade if I cant get any joy in the next few days. Is the servo I need from the freight rover 200/300 series?

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  • 2 weeks later...

Just something i tried recently on the rear of my 7 v8 . Is your supply pipe from the centre flexible connected to the rear brake cylinder in the lower or upper port????

 

I placed the pipe from the centre of the axle to the lower port on the rear wheel cylinder and then ensured the bleed nipple on the opposite side was in the upper port of the wheel cylinder.

air always migrates to the high point so you need to push it uphill so to speak.Solved my problems!!

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Hi Bula

 

I bought a LDV 400 Leyland DAF (not Convoy) brake master cylinder and servo off ebay that has 3 outlets although you blank one as it is not needed.

I couldn't get my master cylinder and servo to work, but I now think I bought an iffy seal rebuild kit.

I will buy another kit and try again when I get the time.

The Sherpa servo operating shaft which contacts the master cylinder is a different length to the originali TR7 servo and I found that when I bolted them together the master cylinder shaft was pushed too far into the bore and locked the brakes on.

This is why I bought a matched Sherpa master cylinder and servo.

I use Dot5 brake fluid.

Hope this helps

 

Regards

Lee

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Hi Roger

 

I use silicone fluid in both the 4A and now the 7 and have had no problems so far that I can say have been caused by the fluid.

I still need to get to the bottom of the problem with the 7 brakes, but as I said I'm pretty sure it is the seal kit. I'm going to get one from a different manufacturer and see what happens.

 

Regards

Lee

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