acaie
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Posts posted by acaie
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Hi
Given the same clutch, the required pedal pressure is proportional to the area of the master cylinder piston divided by the area of the slave cylinder piston. The area depends on the square of the diameter, so if you inadvertently fit a slave cylinder with 10% smaller diameter, the pedal pressure will go up 20%. All to do with the relationship force = pressure x area and the pressure in the master and slave cylinders are the same.
The pedal travel for a given reduction in slave cylinder area area reduces in direct proportion to the reduction in area. so with 10% reduction in diameter, i.e a 20% reduction in area, the travel will go down 20%. All to do with the relationship fluid volume displaced = piston area times travel.
If the pipe isn't big enough, the pedal load will be much higher when you press the pedal quickly compared with gradually.
If the pipe wall isn't strong enough, the fluid will balloon the pipe instead of going into the slave cylinder. Both of these are extremely improbable, because of the large design margins typical for these systems. Without these effects, the pipe characteristics will have no influence.
Hope this helps to understand what may be going on.
Best wishes
Al
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Well done Bizman.
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I'm also minded to try Infinity Exhausts near Yate, since they're just a few miles away. Does anyone have any experience of them?
Thanks for your help
Al
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Have you tried Paul at Phoenix Performance Exhaust Systems in Cullompton? If you give him a call he may be able to help, he would certainly build a quality bespoke system for you if you cant find anything "off the shelf"
Cheers
Ian
Thanks Ian for such an early reply on a Sunday morning - I'm down near Exeter next week, and I'll look in on him.
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My Grinnall V8 is shaping up nicely after 6 months. The exhaust is very fruity and enjoyable, but it does get more than a bit tiring on longer trips, especially with the hood up.
It has a 2 1/2 inch single pipe system, with a small centre box and an oval box at the back, connected to cast iron (SD1?) manifolds.
Any suggestions about where to go near Bristol or the M4 corridor to get part or all of the system replaced with something quieter?
Thanks for any suggestions
Al
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Paul Shepherd at Circuit Motors at Castle Combe did a really good job on mine.
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Progress report
I've now done the driver's seat, with new seat cushion and diaphragm. I think Red5 must have done this stuff before.
As an engineer, getting squidgy foam and stretchy seat covers to line up nicely and glue them together which you can't undo is a bit different from bolting up things which naturally line up and if it doesn't look right, you can unbolt it and investigate why it isn't right.
Definitely a great improvement, definitely worth the trouble, but if you haven't done it before, you won't do two in a morning as Red5 did.
At the moment, the plan is to keep the original seat cushion and diaphragm on the passenger seat, since it seems a lot firmer, but we'll see what we think when we get it out.
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My Grinnall V8 conversion has what might well be the original scoop, judging by its condition and patina(!). It unclipped and clipped back on without any trouble when I was messing about with the carbs and fuel system recently. Happy to post photos if useful.
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Encouraged by Red5's post, I made a start today on the driver's seat which is definitely past its best. The covers are from Rimmers, and came with good instructions, which I would be happy to scan & email.
I've got the old cover off with only very light damage to the foam , which isn't difficult but needs a little time and care. If you're replacing both cushions it would be really easy, because you could just rip stuff off, after making a note or photo of how many clips go where.
I've decided also to replace the seat cushion and diaphragm, and the squab rubber straps on this seat. The cost all mounts up though, with £100 for that lot for one seat, on top of £300 for the pair of covers, by the time you've paid VAT & P&P. The passenger seat is in much better condition, and I'm expecting only to replace the cover to get a good colour match.
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Hi Richard
Hope you're still around, because I'm about to do the seat covers in my Grinnall. Please could you email your instructions to acaie@burtonwilts.org.uk.
I see they're available from Rimmers - is this a good place to get them from?
Thanks in anticipation
Al
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An update. My dear daughters gave me one of these for my birthday in early May, and I've finally got round to fitting it.
I've tried the radio, and playing my Ipod through the Aux socket, and using a memory stick for music, and it's great. I'm even tempted to get a Bluetooth phone because I can.
Super performance, super value, super recommendation.
Thanks, stansoldman
Best wishes
Al
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Hi everyone.
I've put together the following analysis.
- A particular force on the brake pedal results in a particular hydraulic pressure in the brake pipes.
- A particular pressure in the brake pipes results in a particular force on the brake pistons, which does not vary with the position of the pistons - it’s the same whether the pistons are at the top of the bores, the bottom of the bore, or somewhere in the middle, and the same even if individual pistons are in different positions. The forces are balanced by the hydraulic interconnection.
- If the forces exerted by the pistons on the pads, and thus on the disc, are the same irrespective of the position of the pistons, then the position of the disc in relation to the caliper doesn’t affect the forces on the disc.
- So the offset of the disc in relation to the caliper, whilst unattractive from an engineering point of view, does not introduce undesirable new forces in the disc.
- The forces on the caliper are equal and opposite to the forces exerted by the pistons, so the forces on the caliper are likewise unaffected, so there are no undesirable new forces if the disc is offset.
Because the forces are the same despite the offset, I don't see how the integrity of the disc and/or caliper are threatened by the offset.
Likewise, because the forces are the same, there should be no difference in the effectiveness of the brakes.
Provided the disc is still running true, the running clearances between the pads and the disc should be unaffected, so the response time should be unaffected.
So my conclusion is that, whilst unattractive, the offset does not affect safety nor braking performance.
Best wishes to all.
- A particular force on the brake pedal results in a particular hydraulic pressure in the brake pipes.
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I can't disagree with that !Up to you but they should be in the middle.
Stuart.
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I agree it's quite a bit. However, the hydraulic interconnection balances the forces so I don't feel it will threaten to distort the disc. There's no sign of uneven wear on the old pads or the disc.
I'm keeping my thinking cap on and will keep you posted.
Thanks for your interest and advice.
Al
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Link provided by rosey is to BiggRed, who do brake refurbishment/remanufacture. They are friendly helpful and very quick.
Ordered the pins and springs yesterday, and they arrived this morning in 1st class post, fitted by lunchtime. The clearances are extremely tight in the 13 inch alloys - you have to bend the eye end of the pins down a bit to stop them graunching on the inside of the wheel. I wondered why the old pins were bent like this, and when I put the wheel back on, I found out !
Getting the Greenstuff pads in was a bit of a game because the disc was about 1-1.5 mm off the centre of the caliper. To get the inside pad in I had to dispense with the anti squeak plastic bit they give you to stick on to the pad.
Anyway, thank you again rosey.
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I'm changing the pads on my Grinnall V8, which has 4 pot calipers. Took a pad out, and checked it against the drawings available on line, and they are, as expected, Princess pads. The split pins and anti rattle springs are looking their age, so I get some new pins and springs to match. Mistake - of course the Princess caliper has been fitted with a spacer fitted to make it wide enough for the vented disc, so the Princess pins aren't long enough and the anti rattle springs aren't wide enough.
So where do I go from here to identify and buy new pins and springs ? Can you help?
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Thinking about this, with my Grinnall V8 conversion. Is this an event for pure-bred classics?
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I'm very tempted. Do you have to do any fettling to get it installed?
Clutch pipe diameter
in TR4/4A Forum
Posted
If the slave cylinder looks OK, is there any reason to suspect the same sort of issue with the master cylinder?
If you rule out both of them, and you have no reason to believe the pipe might be bunged up, you're left with the mechanical side. Anything sticking or binding either at the pedal end or the clutch end? Anything changed that might affect the lever and pivot point geometry at he clutch end? at the pedal end?
I'm afraid this is all first principles stuff, rather than detailed working experience of sorting TR clutches, but I hope it helps.
Good luck and best wishes
Al.