+2 Dual circuit master options

[mikealdren]

Hi

Do you think its for front rear bias? I thought it would be criss cross. I will have to ask the PO.

Thank you for pointing that out!

Berni

By Criss Cross do you mean LHF/RHR and RHF/LHR? This would be more difficult, you would need two brake lines to the rear of the car. Also diagonal braking in the event of a failure would be worrying.

As I understand it, proportioning valves are generally used to prevent rear lock up by reducing the rear pressure above a threshold rather than reducing the pressure across the full pressure range. They generally give the same pressure front and rear below the threshold. A balance bar with twin cylinders allows true proportioning as well as providing secondary braking in the event of a hydraulic failure.

[mbell]

To update this thread I recently bought another different Spitfire Tandem master. The spitfire tandem master comes in two variants:
1) Pre 1975, "Large Cap"
2) 1975-1980, "Small cap"

Previously I'd bought 2) and that master is too long to fit the +2 RHD as previously mentioned. However 1) is a shorter master, it however has a wider offset reservoir that will not fit along side the clutch master. With the reservoir removed it appears the master will fit with enough room for banjo bolts.

The reservoir on 1) is fitted via flat flange and some screws. So it is possible to replace the reservoir but adapters are required. With (a lot of) assistance of Chuck Nukem we've designed/machined some adapter that will allow fitting of reservoir with 7/16-20 fitting or Tilton ones(https://tiltonracing.com/product/master ... eservoirs/).

I still need to get the reservoirs/banjo for it and will be a few months until I get chance to fit it to the car and confirm its good.

Its not quite a bolt on solution as needs the adapters but a possible solution.

[nwbaxter66]

I think that you might have a runaway Xmas retail success if you decide to put together a production run of these, count me in.
Inspired thinking
Nick

[mbell]

if you decide to put together a production run of these, count me in.

That is one for ChuckNukem not me to decide. I suspect it would need a reasonable sized group buy for it to happen, as while the material costs aren't particularly high I think some extra tools are required and there is quite a bit of setup time to produce them.

I suspect this setup would also work on LHD +2 and RHD Elans and maybe quite a few other cars (e.g. europas). I don't think it would fit LHD Elans but the Datsun master should work for those.

First I need to get the other bits and get it fitted to the car to confirm it is a viable solution. If so I probably post a separate write up.

[nwbaxter66]

Thanks.

[mbell]

Currently got the engine and gearbox out, which gives good access to the brake lines. So decided it was a good time to try the new dual master out.

Initial test fit on the pedal box shows it fits and should be able to connect the brake lines. Should even be able to use the push rod that comes with it by adding a small spacer.

[mbell]

This week I've bought the various fittings and bits and pieces for the master. Now assembled and ready for fitting.

[mbell]

Finished up the new brake lines and did the final fit yesterday. All in ok and seems to be working, maybe needs another bleed.

I did swap out the push rod for my adjustable one rather that packing the master of the pedal box. Looked like might need a bit more that the rubber spacer I made and decided I didn't want to run the risk of the brakes sticking on.

[h20hamelan]

BENDIX R12731
AUTOSPECIALTY M-51001
CENTRIC 130.42001
NAPA 47-5005
NAPA 477-5005
BECK/ARNLEY 072-2710

Closer to the Datsun than the AC Delco
NAPA 39087 is discontinued

Edit RayBestos MC 39805

[nmauduit]

fwiw the usual suspects may offer off-the-shelve options, depending on current stock and tolerable price I suppose (e.g. TTR etc. no affiliation on py part)