More craptastic Parts

Technical advice Q&A

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1954Etype
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#1 More craptastic Parts

Post by 1954Etype » Sun May 11, 2014 11:16 am

When we restored the S2 Grey FHC, new master and servo cylinders were fitted as a matter of course. Bleeding the rears proved problematic and we weren't really happy and told the customer we needed the car back to re-bleed the rears. It passed an mot so the rears were working.

With the car back on the ramp, we bled the rears and couldn't get a decent flow of fluid. Disconnecting the pipe that feeds the rears from the servo, we found there was no pressure on the rear circuit. Despite pressure bleeding, vacuum bleeding, we couldnt get any pressure.

The servo was stripped and rebuilt. On tbe bench, we pushed the actuating rod and got a little bit of pressure on the rears (fronts were fine). We decided to fit a new servo unt and all was fine.

My theory is that the cylnder has been re-bored and is beyond the limit thereby not allowing the seals to wipe against the bore.

I spoke to these guys www.jlspares.com and they rebuild only original units only, lining in stainless steel the cylinders and then fully testing the unit. Has anyone dealt with these guys? Please PM me any comments.

Really frustrating having to strip this unit from a fully restored car. We are thinking of buying new units and testing them ourselves on the bench before fitting.
Angus 67 FHC 1E33656
61 OTS 875047

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harryetype
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#2

Post by harryetype » Sun May 11, 2014 1:30 pm

Angus my heart goes out to you. We have a customer wanting to pick his car on Monday, however after two new servo's we still can't get a firm pedal.

I've had enough of it and from now on we will only rebuild genuine servo's, after all we have a pile of them in the stores. This is why you can't beat rebuilding a good rust free car because you can recondition everything, not just fit repro parts.

Surely there must be a market for quality parts.
Harry

My Dads old V12 TOM 32
1968 Roadster

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Dave K
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#3 Re: More craptastic Parts

Post by Dave K » Sun May 11, 2014 2:33 pm

1954Etype wrote:When we restored the S2 Grey FHC, new master and servo cylinders were fitted as a matter of course. Bleeding the rears proved problematic and we weren't really happy and told the customer we needed the car back to re-bleed the rears. It passed an mot so the rears were working.

With the car back on the ramp, we bled the rears and couldn't get a decent flow of fluid. Disconnecting the pipe that feeds the rears from the servo, we found there was no pressure on the rear circuit. Despite pressure bleeding, vacuum bleeding, we couldnt get any pressure.

The servo was stripped and rebuilt. On tbe bench, we pushed the actuating rod and got a little bit of pressure on the rears (fronts were fine). We decided to fit a new servo unt and all was fine.

My theory is that the cylnder has been re-bored and is beyond the limit thereby not allowing the seals to wipe against the bore.

I spoke to these guys www.jlspares.com and they rebuild only original units only, lining in stainless steel the cylinders and then fully testing the unit. Has anyone dealt with these guys? Please PM me any comments.

Really frustrating having to strip this unit from a fully restored car. We are thinking of buying new units and testing them ourselves on the bench before fitting.
I saw J&L spares at Stoneleigh about 8 years ago and after talking to them sent my two original MC's to be sleeved and rebuilt.
After fitting all seemed OK but when I stopped on any sort of gradient the car stopped still without using the handbrake, it was in fact like having an auto handbrake.

I took the car to Rob Beere to have his new remote servo fitted and he told me that he had to replace to rear MC because it was sticking.

As you know I have had some problems with my brakes (my doing BTW) through last year. I decided to rebuild the rear MC and found even with no seals on the piston assembly the piston wouldn't slide down the bore of the MC.
I had to put the MC in a 4 jaw at work and hone the bore, I then had to polish the piston with scotchbrite to get a nice sliding fit. The front has always been OK.
They told me that they don't sleeve the MC's with st.st only mild steel. Things might have changed.

They did a great on job on my wiper motor, they don't do them any more I have heard.

Dave

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#4

Post by 1954Etype » Sun May 11, 2014 2:59 pm

Good info, thanks Dave
Angus 67 FHC 1E33656
61 OTS 875047

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38E
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#5 Re: More craptastic Parts

Post by 38E » Tue May 13, 2014 1:12 pm

Dave K wrote:
They told me that they don't sleeve the MC's with st.st only mild steel. Things might have changed.

Dave
White Post did all my master cylinders years ago and they have always used brass for sleeving, not stainless steel.
Clive, 1962 Coupe 860320
(sold)

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#6 Re: More craptastic Parts

Post by 1954Etype » Tue May 13, 2014 3:54 pm

Interesting. I wonder why not use stainless unless it is too hard to work with....
Angus 67 FHC 1E33656
61 OTS 875047

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iani
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#7 Re: More craptastic Parts

Post by iani » Tue May 13, 2014 4:14 pm

I wonder if it's to do with the different grades of stainless that are available, note how many people are surprised when their stainless exhaust systems show signs of corrosion after a short period. Marine grade stuff is fine but a lot of the material out there doesn't have the water resistance qualities that you'd ideally see in a hydraulic chamber, perhaps brass is a better bet?

Ian
E-type - TBC
1968 Triumph GT6 Mk1

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