Richard_M Posted December 28, 2012 Share Posted December 28, 2012 Anyone know what the ratio of the brake servo on a 2500 PI is?My research suggest 1.9 to 1, but I'm struggling to get confirmation.Any takers?Richard Quote Link to comment Share on other sites More sharing options...
andy thompson Posted December 28, 2012 Share Posted December 28, 2012 I always thought 3:1 but have no proof Quote Link to comment Share on other sites More sharing options...
Richard_M Posted December 28, 2012 Author Share Posted December 28, 2012 Thanks for the input Andy but, my bad, I mis-described the servo.This is for a Mk1 PI - not Mk2, so it's the remote servo type.Whether this makes a difference to the ratio is perhaps another thing altogether.CheersRichard Quote Link to comment Share on other sites More sharing options...
mikeyb Posted December 28, 2012 Share Posted December 28, 2012 no idea on ratios but I believe the Mk1 PI servo has the greatest assistance of the lot! Quote Link to comment Share on other sites More sharing options...
thescrapman Posted December 28, 2012 Share Posted December 28, 2012 Mk1Pi does have the largest servo as it has no vacuum tank.Do you have a problem with yours?Or are you just curious.CheersColin Quote Link to comment Share on other sites More sharing options...
Richard_M Posted December 28, 2012 Author Share Posted December 28, 2012 Curious? Always :)The one I have is in need of a rebuild - but I've seen this and others:http://www.ebay.co.uk/itm/400368964719?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2648Same type and style - but not sure if the Mk1 PI had the same ratio... Quote Link to comment Share on other sites More sharing options...
thescrapman Posted December 28, 2012 Share Posted December 28, 2012 You need the very large diameter of the original to compensate for the lack of manifold vacuum. It is not the ratio that is important in this case.A rebuild ain't cheap, as you have to pay Aston tax on it. :-(You could fit a Stag servo and a vacuum tank. Requires a bit of panel beating and a change to a few other things.I bit the bullet and paid the Aston tax.CheersColin Quote Link to comment Share on other sites More sharing options...
Richard B Posted December 29, 2012 Share Posted December 29, 2012 I think the MkI PI servo & master cylinder give better brakes than the MkII PI.PITA to work on the metering unit though. Someday I'm going to have a couple of flexible hoses fitted to the servo to make it easier to move it out of the way. Quote Link to comment Share on other sites More sharing options...
Richard_M Posted January 4, 2013 Author Share Posted January 4, 2013 Thanks for the input on this - it seems the actual ratio of Mk1 Pi master/servo is a mystery lost in Standard Triumph...I've ordered the 1.9:1 version - the supplier assures it's correct for the car. We'll see...Richard Quote Link to comment Share on other sites More sharing options...
thescrapman Posted January 4, 2013 Share Posted January 4, 2013 YOu might need to invest in a vacuum tank to help the servo.Have you tried driving it without the servo?? Or even with it below par.Interesting... :-/You could try PAst-Parts at Bury st Edmunds, they may be able to assist (either with the ratio, or a rebuild when the time comes.)CheersColin Quote Link to comment Share on other sites More sharing options...
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