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8 & 10 cyl Bristol cars Type 407 onwards - restoration, repair, maintenance etc

410 Brake Upgrade

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Old 04-10-24, 08:46 AM
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Default 410 Brake Upgrade

Am mulling over a brake upgrade for the 410. I see that various kits are available from SLJ, Coopercraft, Fosse Way and no doubt there are others, that provide you with an uprated caliper and the option of vented discs.
I'd be interested to hear from anyone who has actually fitted one of these kits and whether it's worth it/makes a huge difference and if there are any downsides.
Thanks
Andrew
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Old 04-10-24, 09:36 PM
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What issue do you have with the brakes? If you feel you need to press the pedal harder than you would like it's worth checking which servos you have fitted. The originals were 4.5: 1 and hard to find so may have been replaced with a lower ratio.
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Old 05-10-24, 07:53 AM
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Andrew
Have you considered having you brake calipers and Servos refurbished? I would also replace the discs and fit new brake pads all round.
The company I have used several times in the past (with different cars) are called Classic Car Automotive at Chelford near Knutsford.
Brian
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Old 05-10-24, 10:11 AM
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Andrew

Whilst I shudder at the thought of what you improvements to your 410 are costing you I do think that an upgrade to ventilated discs at the front is a must if you are thinking of touring in any even vaguely mountainous part of the world.

The standard set up is excellent in one sense in that while a 410 will put out stop almost anything on the road today, once, including modern BMWs (I recall a very surprised BMW when everything came to a sudden stop on that dreadful motorway around the top of Milan) there is a catch in that there is nowhere for the heat to go and repeated application of the brakes will rapidly result in the them rapidly fading away to nothing.

I always found myself having to nurse the brakes when dropping down a mere 650 feet over two and a half miles down a local lane at 20 mph max due to the lack of visibility and passing places.

I ended up having a slightly alarming and humbling experience on an alpine tour. Humbling in that I was reduced to crawling down the longer passes with the transmission in 1st and was being passed by bicycles. One rider even had his feet on the handlebars.

I much commend ventilated front discs, I used SLJ.

Ill health then intervened and the subsequent custodian has gone one further and has fitted ventilated Jaguar wheels.

Oh, by the way, don’t believe the hype about the 410s dual systems. They are connected by a balance bar and if the front brakes fade the pedal will just go to the floor without having any effect whatever on the rears. (This very over hyped feature was one also shared by the E type Jaguars)

My regards
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Old 05-10-24, 11:13 AM
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Very interesting to see Roger's reply. I can understand a single experience of that sort instigating a major upgrade.

I never suffered this sort of issue but I never did much driving in the mountains. I seem to remember a report that John Bolster tried to get the brakes on a new 410 to fade but couldn't manage it.

The fade that Roger refers to with the front master cylinder bottoming out would be caused by water in the brake fluid boiling. It is really important to change fluid regularly. There are now very cheap moisture content testers available. I try to remember to test all the family's cars at least once a year.

An alarming braking experience I had in a 410 was when the entire block of friction material parted company from the pad plate. The car had been unused for some years and I think water had got in between the friction material and the back plate and then frozen.

It took about three pumps of the pedal before the back plate started scraping on the disc and enough pressure could be built up in the other brakes to stop the car.

I now replace all pads on cars new to me regardless of how much material is left.
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Old 05-10-24, 03:17 PM
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Quote:
Originally Posted by David C View Post
The fade that Roger refers to with the front master cylinder bottoming out would be caused by water in the brake fluid boiling.
I’m sorry, I seem to have given the wrong impression by including my last paragraph regarding another potential fallibility of the 410s brake systems. I should also have said fail rather than fade.

I ran a maintenance schedule which was based on Bristols recommendations but rather more rigorous. This included changing out the brake fluid on a very regular basis. Pads were also new and the discs relatively new on the alpine trip

I believe the fading I experienced resulted from overheated pads and unventilated discs (the pad material just doesn’t bite if it all gets too hot) rather than boiling fluid. I don’t recall the brake pedal hitting the floor as happens if the fluid boils.
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Old 05-10-24, 03:44 PM
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Sorry to jump to conclusions. That's really interesting. What make of pads were you using? I always used genuine Lockheed - now Delphi - and never managed to get fade. Obviously not trying hard enough, but as mentioned I never drove anywhere with really long descents.
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Old 09-10-24, 09:31 AM
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Thanks for all the replies - much appreciated.
Re continuing investment (Roger) I console myself with the fact that it is probably less than the annual depreciation on our modern cars and I do enjoy it as we're now at the stage - most of the time - where money spent results in improvements, rather than fixing stuff one thought was ok.
Have done many thousands of happy and swift miles throughout Europe this spring/summer, without incident so I'm very happy.
The only real issue I have with the brakes is that once it's been sat for a while, on the first push of the brakes you meet some resistance but not much happens, then you keep the pressure on and the the pedal goes to its normal position and you have normal braking. After that first push, it works perfectly. David has already suggested that first port of call is to work the piston back and forth and just have a good visual inspection.
The pedal requires quite a bit of effort, but I have no benchmark. It certainly requires one to stand on it a bit when hauling down from high speeds.
The servos were done by SLJ when I bought the car as well as overhauled callipers, discs and pads.
I did the BODA sprint at Southport and it coped well with late, hard braking with good bite.
On reflection and re-reading your replies, it seems a good idea to have a proper look at the callipers, followed by the servo - just to make sure it's all working as it should, and go from there. It's a repro servo and I've had fun and games with them in the past on other cars.
Will keep you posted. Any more thoughts, keep them coming please
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Old 10-10-24, 12:43 PM
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I find my 410 brakes quite heavy but effective. I've only ever faded them once, on a spirited drive along the A421 in Milton Keynes, where there are 12 roundabouts connected by short stretches of dual carriageway just long enough to get up to 70 or 80 before braking hard for the next roundabout.

I have however cooked them quite thoroughly in mountains before now. No fade but lots of smoking when coming to rest. I think vented discs may be an improvement.

I know one chap who took his 411 around Castle Combe with enough gusto to have the paint on the Jaguar alloys fitted visibly bubbling and boiling when he came back in, but he said the brakes still worked perfectly.
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Old 16-10-24, 10:34 AM
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Some further thoughts:

I fear I cannot definitively confirm the pads I was using as my records stayed with the car but they were as fitted by both BCS and SLJ.

My issue was always with very long descents coupled with the lack of engine braking. Garmin reported that we had risen and fallen more than 26 miles on the Alpine trip, Le Havre to Le Havre.

I don’t believe that my car differed from the norm - I could only get engine braking in 1st and it would only actually drop into first at about 6 mph, which tended to hold up the traffic.

I always found the brakes brilliant in every other circumstance. They were heavy compared to modern practise but in that pre ABS era designers had to balance out the risk of lock up and resultant lack of control and the only way they could achieve that was to make sure you had to push down very hard before the brakes would lock. A design balance that was taken to extremes in the Morris Minor which will actually stop on a sixpence without locking its brakes provided sheer panic provides sufficient impetus to your right foot!

Here’s a picture I took from the top of the Stelvio for you. I forced the poor old lady up but found a rather gentler way down!
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Old 18-10-24, 05:47 AM
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Thanks for the further thoughts and reminiscences of the dreaded Stelvio!
Have done it once in a modern and that was enough - a BMW X5 - relying on the gears towards the end to slow it down.
Back on the benchmark thing DavidC of this parish, has kindly suggested that I hold onto my £'s for a short time while his 410 completes the next stage of its rebirth.
By then it will have the correct original rebuilt servos and rest of braking system in fine fettle, so I should be able to see what it was like when "new".
My car is a also on slightly wider wheels and I've often wondered (see my wanted ad) what it'd be like on the wheels it was designed for.
So plan is to meet up, try each others cars, swap wheels around and so on.
I imagine there might be some comparative acceleration tests as well.....
Will keep you posted.
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Old 18-10-24, 09:23 AM
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It just occurred to me that I should have asked sooner which brake pads you have fitted. If they are a slightly harder compound they will need a push or two to wake them up. When I first drove my 403 with 406 brakes it was hopeless until they had warmed up as someone had fitted far too hard a compound. When I asked about what different grades were available I was told that towards the end of production of Dunlop Disc brakes the remaining stock was sold to Thwaites Benford for their dumper trucks. Apparently during construction of the M40 quite a few of these suppered serious fade and a few took serious tumbles. The solution was to have rings of solid copper in the brake pads!

I tried a few different manufacturers and settled on Lockheed as having the best temperature range. I think they are sold as Delphi today.
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