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Discussion Starter #1
Hi all, After a long day trying to resolve my brake problem I've given up and ''thrown in the towel''
My 1973 GTV has been off the road for 5 years. I've thrown out both servos and the tandem master cylinder and replaced it with one new servo and one new 0.75 master cylinder (girling type) - a single circuit system.

I cannot get a firm pedal when I bleed it. I've used a pressure bleeder and then tried a friend sitting in the car doing the up-down-up-down routine. I started at the rear most brake caliper first and worked my way forward. The system was full of air and when I've done them all the pedal still goes tothe floor.

Do I need to bleed the servo and if so what is the technique?
(The new servo is in original situ' against the bulkhead)

How can I check if one of the threaded pipe connectors is leaking/ not sealing? as there are no visual fluid leaks

Any help please.... it's now a simple single circuit with one m/c and a new bendix servo.

Does the engine need to be running when bleeding?

Ho
 

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Is your car left hand drive? Are you saying that you have a single line master cylinder feeding all four calipers???:confused:
If thats a yes it is not only insane,but also the answer to your long pedal,not enough fluid displacement.:tut:
If i misunderstood please explain ,maybe post pics.
 

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Discussion Starter #3
Errrr! Yes, It's a RHD spec car - with standing pedals. I do have one master cylinder (0.75" Dia) feeding all four wheels with the in-line servo.

My rationale for doing this was that I have seen similar 105's with this set-up at a recent Alfa track day and Alfaholics do sell a conversion kit to do this for people who want to avoid the expense and issues with tandem m/c's and twin servo's.

This new circuit is no different to the circuit on, say, a mk1 escort Mexico or RS2000. And the RS was Fords' equivalent type of vehicle at that time.

Comments please.....
 

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OK,i am trying to help you here,so is it a single cylinder with a single line or a single "dual"line one?
And how have you connected your pedal to the cylinder. twistingbar?
 

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Discussion Starter #5
Yes - I thought I should have mentioned that. I've adapted the original link rod from the pedal (under the floor) to the (new) master cylinder. The principle is exactly the same as the original type.

It's a single circuit.

In place of the old tandem m/c I've made a strong mounting bracket and located the new girling type master cylinder within the bracket so that the location of the new m/c is in exactly the same as the original.

The fluid supply comes from the original reservoir to the rear of the new m/c (1/4" bore) and then 3/16" brake pipe - out - going into the side of the new servo on the B/head.

From the servo outlet the brake pipe then goes into a new T-piece (new additional T piece into original brake system) with one outlet feeding the RHS front brake and the other outlet feeding into the original T piece (in orginal situ' and has brake light switch). The two outlets of this original T-piece feed the LHS front brake and the other outlet supplies the rear sytem, as original.

My selection for the size of the m/c (0.75") was based upon my other car - a Mk1 Ford Escort with front discs but rear drums and this uses a 0.75" bore m/c. What do you think?.......
 

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I still think it is insane running a single circuit master cylinder,but in any case if you have a long pedal ,there are no leaks and no air in the system then your master cylinder bore is too small.:)
 

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Discussion Starter #7
Single circuit is not ideal - hence my reason for buying a new servo and new m/c. The m/c could be too small, I can't tell yet because I cant seem to purge out all the air. I get good pressure from the nipples when bleeding, but the pedal doesn't stay hard - I'll try again tomorrow and post back a response, hopefully there will be a puddle of fluid under the car tomorrow identifying the location/cause. Thanks, Andy
 
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Try eliminating the servo as a starter - I may be mistaken but I thought the girling conversions all operate without a servo, but whether you have the right size m/c is another matter.
 

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The Girling conversion we sell is designed to work with or without a servo. We just sell you a different bore master cylinder depending on whether your car has a servo or not.
 

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Discussion Starter #10
Mound Dawg, It's a fair cop - I saw a few cars similar to my 2000GTV at the Castle Coombe track day running with single servo's and when I asked I was told it was a single circuit set-up.
As this was similar to my Ford Escort I thought it wouldn't be too hard a job to do.
A quick trip to Alfaholics to buy a servo and few other bits and pieces and it would be done - or so I thought!!
As there was no puddle of brake fluid under the car this morning, I'm fairly sure there are no air leaks so the m/c must be too small - if Alfaholics sell the m/c separately I'll collect one on Tuesday morning along with more bits as I desperate to get this car Mot'd and on the road.............
 

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You haven't dropped into the same silly mistake I made have you???.

The set up on my 1750 GTV is similar to yours, Girling m/c single circuit with servo. I struggled for ages trying to get a pedal.... eventualy I realised I had the rear calipers upside down, yes it's possible!!, if you put them on the wrong side. Obviously the air was trapped at the top as the bleed nipple was at the bottom:rolleyes:

I felt a bit if a t*t.. but once sorted it worked fine.

I'd swap my 2000GTV to this set up but I'm a little unsure about the insurance as it sounds less safe than the dual circuit, in truth the dual circuit M/C is so dodgy that it's probably safer.
 

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Discussion Starter #13
Well the saga continues: with the new single circuit set-up I purged the brake system with a pressure bleeder and to make absolutely sure all the air was out I went around each caliper using the traditional up-down method. The result was a firm pedal albeit with a bit more travel. I drove the car up and down my lane a few times and everything was working OK. At the weekend I got back in the car put my foot on the pedal and it went striaght to the floor - no brakes again!!!!!! My set up has a new Girling 0.75 m/c and brand new Bosch servo (Bonaldi look-a-like), I checked all the connections - all dry. I checked that the rear calipers were on the right way up (previous post) and all OK there. It can't be expanding brake hoses as I had good pressure when I put the car away. I've no loss of fluid from the reservoir. Faulty servo? it works when the engine starts.
I'm stumped and really want to get the car back on the road - I was hoping to take to the Alfa day but took the family hack instead. Now I'm aiming for the Italian day at Gaydon in September (?)
Alfa Tuner: I've decided also to revert back to the original dual circuit system, I'm going to get my Bonaldi m/c re-conditioned and one of my Bonaldi servos re-conditioned. After installing the single circuit I can't say I was particularly comfortable with the set-up even when it was working, and trying the brakes a few days later and finding all that pedal travel has convinced me to change, so thanks. What else can I do or check?? I'm sure the problem will still be there when the new (re-con) m/c goes back on and the other servo..................
 

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I would stick with debugging the single circuit system as that will be easier. If you're right about the calipers, hoses and unions being sound then I would suspect the master cylinder or servo. You could bypass the servo with a short length of brake pipe to eliminate that from your inquiries.
 
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Hi,

Sorry I might ask some stupid question:
when you took back the car and the pedal went to the floor, was it a difference of brake liquid?
You have change the MC and servo, what have you done on the caliper, flexible pipe?
Have double check that the servo is properly installed and connected?
Correct brake fluid?
when the brakes were working have you experience some white smoke from the exaust?
I agree you might want to go to a specialist, it's better than loosing your brakes while driving...
All the best

Andre
 

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Well the saga continues: with the new single circuit set-up I purged the brake system with a pressure bleeder and to make absolutely sure all the air was out I went around each caliper using the traditional up-down method. The result was a firm pedal albeit with a bit more travel. I drove the car up and down my lane a few times and everything was working OK. At the weekend I got back in the car put my foot on the pedal and it went striaght to the floor - no brakes again!!!!!! My set up has a new Girling 0.75 m/c and brand new Bosch servo (Bonaldi look-a-like), I checked all the connections - all dry. I checked that the rear calipers were on the right way up (previous post) and all OK there. It can't be expanding brake hoses as I had good pressure when I put the car away. I've no loss of fluid from the reservoir. Faulty servo? it works when the engine starts.
I'm stumped and really want to get the car back on the road - I was hoping to take to the Alfa day but took the family hack instead. Now I'm aiming for the Italian day at Gaydon in September (?)
Alfa Tuner: I've decided also to revert back to the original dual circuit system, I'm going to get my Bonaldi m/c re-conditioned and one of my Bonaldi servos re-conditioned. After installing the single circuit I can't say I was particularly comfortable with the set-up even when it was working, and trying the brakes a few days later and finding all that pedal travel has convinced me to change, so thanks. What else can I do or check?? I'm sure the problem will still be there when the new (re-con) m/c goes back on and the other servo..................

If you bled the system and it had a firm pedal and consequently a day later it went soft again,then it is taking in air past the seals ,normally from the master cylinder,although it has been known for the calipers on these cars to do do the same:)
 

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Possibly the pistons on one of your calipers is seized that is the problem I'm currently having on mine. I've got a tandem braking system . Car was parked for 2 years reconditioned both my brake boosters and serviced my front calipers and left the back unserviced bled the brakes and managed to get front brakes can feel it on the pedal whilst bleeding the back pedal was coming up and then running apoun investigtion found out that one of my rear calipers the pistons was seized .
 

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You need to start at the nearest wheel, go n/s front then o/s rear.........o/s front then n/s rear, use the up-closed down-open with a mate on the spanner, tiresome but the best way, try running the engine while doing it, but if there is no obvious leak then the seal in the master cylinder is duff, just because it is new dont make it right

An off the wall idea you might want to try.........because it happend to me.

Same as you, every time I bled up, now if you look at the bulk head servo side, you will see two wires going into a micro switch at the joint between the brakepipes, the switch was shorting, heating up and boiling the fluid, hence no pedal.

And if it is that, the same switch can be obtained from an MG/Layland dealer because its also fitted to a mini
 
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