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Remote Brake Servo Spitfire 1500


Bob Owen
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Increasing the Dia of the M/Cyl. Reduces the mechanical advantage. Unless the same Factor is introduced to the Slave(s). (Pascal) By My calculation (5/8" to 0.7") About 16% reduction. Requiring extra Pedal Pressure?.

Pete

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12 minutes ago, PeteH said:

By My calculation (5/8" to 0.7") About 16% reduction

5/8" to 0.7" is 0.625/0.7 by bore, which needs squaring to get area, giving 0.797, so a 20% reduction by my reckoning.

5/8" to 3/4" is 5/6 by bore, or 25/36 by area, or a 30% reduction.

Either way, the corresponding increase in required pedal pressure is substantially less than the gain of a servo.

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19 minutes ago, NonMember said:

5/8" to 0.7" is 0.625/0.7 by bore, which needs squaring to get area, giving 0.797, so a 20% reduction by my reckoning.

5/8" to 3/4" is 5/6 by bore, or 25/36 by area, or a 30% reduction.

Either way, the corresponding increase in required pedal pressure is substantially less than the gain of a servo.

With O/E M/C`s over £100. And AMG ones at 1/2 that price. It`s tempting to go for it. And add the servo?. When I`ve finished cleaning up the Very grotty originals I`ll look at it

Pete

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I have wide feet and have to be careful which shoes I wear in the GT6 else I get the dread brake accelerator combo. And of course stage one tuning on a Triumph is to remove the accelerator stop from the pedal.

Doug

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Silicone brake fluid is based on silicone oil. Silicone oil - I was surprised to find - is NOT compatible with silicon rubber! So it's POSSIBLE that they've used silicone rubber seals. However, I agree it's much more likely that they simply haven't tested DOT-5 silicone brake fluid and they won't warrant something they haven't tested.

When you work in electrochemistry you start to get a bit nerdy about chemical compatibility!

Cheers, Richard

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On 01/02/2021 at 09:14, clive said:

. Did the tack laps at Spa almost 2 years ago, but I had to be brave and resist using the brakes as much as possible to prevent fade. A bigger brake setup is on the cards)

Trackerjack type?

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1 hour ago, thescrapman said:

Trackerjack type?

Sort of. I bought some new late escort calipers at a very good price, and they use a 240mm vented disc. I have some golf discs, which have been opened up to fit. I will make the caliper mounting and re-drill the discs at home, how hard can it be? (I have previous, I made the rear disc setup on my spitfire)

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I know we all try and "improve" our vehicles. I do however wonder where the line can be drawn?, over what is "too far"?. Probably more concerning would be "our" insurers attitude, to many of the more extreme modifications. Even if they are done in the principle of increasing safety?.

Food for Thought?.

Pete

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22 minutes ago, PeteH said:

I know we all try and "improve" our vehicles. I do however wonder where the line can be drawn?, over what is "too far"?. Probably more concerning would be "our" insurers attitude, to many of the more extreme modifications. Even if they are done in the principle of increasing safety?.

Food for Thought?.

Pete

I have found Peter James to be very accommodating with my cars. On my toledo, they are not loading the premium despite a sprint engine being fitted as it is "in the family". Saying that it was initially a 1500 when purchased, then 1850, but never seen an increase. On the other hand, Footman James were a nightmare a few years ago, and were very unhelpful

12 years ago I insured with Peter Taylor (they included club road rallying at that time). When I got my quote, they asked about modifications. "yes, ford zetec engine and gearbox, plus uprated brakes and suspension". Their reply "that is not something we worry about" and no loading of premium. That was the year I wrote the car off, and no issues (except the underwriters being difficult about letting me have the car back, sorted by Peter Taylor)

So choose your broker with care. 

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5 hours ago, PeteH said:

I know we all try and "improve" our vehicles. I do however wonder where the line can be drawn?, over what is "too far"?

It's been argued many times... in fact the originality of our cars has been so derided by many modifiers I wonder why we're not all dead many times over.

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Well. I gave the old M/C a further bout of cleaning, not happy with the results as it looks as if the Bottom of the cylinder is badly wasted, (where I assume the Lower seal sits?). Connected the Endoscope to the laptop, and took a closer look:- (Snapshot).

image.png.479526607647fc41191371ae15442c48.png

 

Not looking at all well. I think new is in order?. Now its choices time. O/E at £102-00?, Or up the ante, and replace with (cheaper) 0.7" device at half the price?, which would also cover the cost of a Servo?, and still come in at under £100? Total?.

Hmmmmm?.

Next job is to clean and check the Clutch M/C.

Pete

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5 hours ago, clive said:

(except the underwriters being difficult about letting me have the car back, sorted by Peter Taylor)

When the "lady" wrote my Fiat off taking out the Door and Wing, ("Not economically viable repair") In Morrisons car park. The then insurers where non plussed when I ask to buy the salvage. 2 weeks later, second hand door and wing and a new MOT. It was back on the road. Doing my bit for the planet?.🤣 by re-cycling?.

Pete

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19 minutes ago, Pete Lewis said:

Been Looking at some of these. There is one which is 5/8". BUT the seller stated for "Front DRUMS". Any idea why that should be?. Different stroke?. (It looks identical to O/E) The other(s) appear to be 3/4". Which to my mind would necessitate of increased Pedal pressure?. (OK, I know that could be offset with a servo).

Pete

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24 minutes ago, PeteH said:

When the "lady" wrote my Fiat off taking out the Door and Wing, ("Not economically viable repair") In Morrisons car park. The then insurers where non plussed when I ask to buy the salvage. 2 weeks later, second hand door and wing and a new MOT. It was back on the road. Doing my bit for the planet?.🤣 by re-cycling?.

Pete

That's how the accident repair places make most of their money; charging Insurance Companies massively inflated prices to repair cars. My daughter's 107 was written off, not because of minor damage to the front bumper, but because the airbags had deployed and the cost of a brand new bumper and a brand new dashboard, with airbags, was too great. The new buyer fitted a second-hand dash and a replacement front bumper from a scrapped 107 and it's still on the road not far from us. Accident Repair facilities don't use second-hand parts due to the risks involved, but a private buyer can, at vastly reduced cost.

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3 minutes ago, PeteH said:

Been Looking at some of these. There is one which is 5/8". BUT the seller stated for "Front DRUMS". Any idea why that should be?.

Probably a smaller reservoir, which would not hold sufficient fluid for disc brakes. You need the MC extension, or a larger master cylinder which has the same bore but greater fluid capacity.

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13 hours ago, PeteH said:

I know we all try and "improve" our vehicles. I do however wonder where the line can be drawn?, over what is "too far"?. Probably more concerning would be "our" insurers attitude, to many of the more extreme modifications. Even if they are done in the principle of increasing safety?.

Food for Thought?.

Pete

Pete, if you ever get the chance, drive a Sprint with standard brakes.

Take clean underwear with you! 

 

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36 minutes ago, thescrapman said:

Pete, if you ever get the chance, drive a Sprint with standard brakes.

Try a TR7 with standard brakes! Same pads as a Mini.

(Admittedly mine also had a Sprint engine and we were doing RBRR in convoy with a shockingly unreliable other TR7 Sprint, so the dismal brakes got a thorough wear work out.)

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