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disc protectors/splash guards/splash shields

Technical issues not related to a DLOC car marque, eg tyres, ethanol, other car makes, etc. and legal, political and insurance
Brian-H
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disc protectors/splash guards/splash shields

Post by Brian-H »

I've moved this post myself from this thread viewtopic.php?p=34972#p34972 . Reason is that I can expand on it further, if required.

Any car with disc brakes (front or rear), if the car came from the factory with splash guards/shields fitted, they are only an MOT fail if they are loose or badly corroded. If they are removed entirely, it is no longer an MOT fail. This even applies if a guard/shield is removed on one side but not on the other. So they are not classed as a safety feature.

Indeed, it's not clear what they were supposed to do, as some cars never had splash guards/shields fitted
e.g. Jaguar Mk 10, if/when the car came factory fitted with disc brakes all round (i.e. front and rear), never had guards/shields fitted.

Jag Mk10 Front
Jag Mk10 rear


Others had guards/shields fitted on the rear but not on the front e.g. Jaguar Mk 2
Jag Mk2 Front
Jag Mk2 Rear

EDIT - I just noticed that the diagrams are watermarked so I've put the links instead
Last edited by Brian-H on Mon Feb 01, 2021 3:07 pm, edited 2 times in total.

Brian-H
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Re: disc protectors/splash guards/splash shields

Post by Brian-H »

Jaguar E-Type Series 3 had guards/shields fitted on the front discs, but the rear discs were inboard so no shields required at that location, yet they had cooling ducts (which would let water spray onto the discs)

Jag E-Type Series 3 Front
Jag E-Type Series 3 Rear


EDIT - I just noticed that the diagrams are watermarked so I've put the links instead
Last edited by Brian-H on Mon Feb 01, 2021 3:11 pm, edited 1 time in total.

Brian-H
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Re: disc protectors/splash guards/splash shields

Post by Brian-H »

About 5 years I did a bit of internet searching to find out why some cars have disc shields fitted.

e.g. early Dunlop and Girling advertisements for disc brakes, early Dunlop disc brake patents , very first disc brake (Lanchester 1902), disc brakes in aircraft, disc brakes in racing cars, first mass production car using disc brakes (1955 Citroen D series).

Brian-H
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Re: disc protectors/splash guards/splash shields

Post by Brian-H »

Below are Girling and Dunlop adverts for disc bakes from 1957 car magazines, note that disc brakes had only started to appear on cars around that time.
advert_Girling_nov57.jpg
advert_Dunlop_jun57.jpg
At the time, Girling was a brand that was part of Lucas, but Dunlop was an independent company that was into tyres for all sorts of transport, as well as anything associated with wheels, such as brakes. As a result, Dunlop were heavily patenting their brake designs.

"Dunlop brake disc patent" in Google threw up some interesting information. Some excerpts from Google Books show that Dunlop patented disc brakes for aircraft, and then for cars in the 1950's. One excerpt states that reliable disc brakes first appeared on the Jaguar C-Type (Dunlop design), the Citroen DS, and the Triumph TR3 (Girling).

In particular, someone called Henry James Butler was filing the Patents for Dunlop in the US (Dunlop Co must have realised that patenting in the US was imperative). This website was the best for searching for Patents, particularly in the US. Searching in there for "henry james butler brake" (without quotes) threw up loads of patents, in particular "Brake with dust shield".

Here it is, US2746577
US2746577A_fig1.jpg
This was first filed in 1951, and as far as I can tell, it is the first patent for a "dust shield" for disc brakes.

The disc (diagonal hatching, labelled 1 and 3) is fully enclosed. The pipe 12 is stated to be a source of compressed air, which can be applied to keep the disc cool. Butler starts off by saying that disc brakes are used in aircraft and implies that they aren't so much of an issue in aircraft and goes on to say "when a disc brake of the type described hereinabove is used in a road vehicle however, it is found that dust and road dirt adhere to the radially extending sides of the disc with the result that when the brakes are applied, the disc is scored and abraded by particles of grit and the like whilst the pads of friction material are very rapidly worn down". He then says that the patent is to prevent this and states that, in conjunction with the amount of compressed air, heat dissipation would be "optimised". He says that the patent is applicable to aircraft, road cars, and large road vehicles.

His patent cites 7 other patents (by other people): 2 of which are for cooling of drum brakes; 1 for shielding the entire drum (for similar reasons to his own patent) ; 2 for single brake disc design; and 1 for a disc wiper (1950, shown below).

Here is the latter, US2496699
US2496699A_fig1.jpg
Bruce E. Clark (patentee for Chrysler of the above) states "One difficulty with [disc brakes] has been found to be that the portion of the disc which is exposed to the air is also exposed to dust, water, mud, slush, and similar road dirt. The presence of this road dirt on the disc is detrimental when the dirt comes into contact with the friction element. Water and dirt radically change the coefficient of friction of the element on the disc and wear of the parts is accelerated. I have provided means to remedy this defect by preventing the road dirt from coming into contact with the friction disc. I provide a means for cleaning a localised area of the disc and always presenting a clean disc surface in alignment with the friction element. In addition I seal the movable member itself from direct contact with the road dirt."

Although the latter design is possibly more practical of the two, one has to ask
1. why were these types of patent being proposed ?
2. why were they never fully implemented ?

The answers are probably
1. in the 1950's disc brakes were new on cars, also bearing in mind that in the 1940's and 1950's roads were "un-paved" in many parts of the US and Europe, and that the early materials used to manufacture discs and pads may not have been durable, so these patents were "contingencies" in case such problems became apparent over time.
2. fabrication and maintenance of the designs would have been more difficult than actual maintenance of the disc and pads themselves

As a result, brake disc shields evolved into something more-or-less resembling an umbrella, and like an umbrella, shields are not going to do a great deal in heavy rain conditions. Indeed, in my experience they can make conditions worse, including trapping stones.

But I still wonder why some cars come with them fitted on one axle, both axles, or not at all on some cars.

Christopher Storey
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Re: disc protectors/splash guards/splash shields

Post by Christopher Storey »

You might be interested to know that the first manufacturer to try disc brakes was Chrysler c.1950/51 but for some reason they were unable to make them work properly ( probably high pedal pressures were an influence ) and abandoned them very quickly . Also, the original Dunlop patents for aircraft discs also incorporated the first application of anti-lock technology, known as Maxaret

Brian-H
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Re: disc protectors/splash guards/splash shields

Post by Brian-H »

^ you triggered some vague recollections of that - when doing the searches 5 years ago, I downloaded quite a bit of stuff into a folder :geek: and also bookmarked :ugeek: quite a lot - all on another laptop that's been carefully stored in the loft for the last 3 years. I took the previous content from the folder in that laptop, went back again just now and copied all the bookmarks onto this laptop.

As well as this google book excerpt and another google book excerpt I also bookmarked this article.

The latter mentions a 1949 Chrysler system, saying that it "did not incorporate a caliper clamping down on a disc; instead, they relied on the engagement of a pair of discs rubbing against the inside surface of a cast-iron drum". It also says that "the Indiana-built 1949 Crosley was first fitted with Goodyear/Hawley disc brakes on all four wheels. Unfortunately, these calipers, which were initially designed for airplanes, couldn't stand up to the repeated use demanded by the automobile, and thus proved troublesome". The article also says "For years, it's been widely acknowledged that Jensen was the first manufacturer to adapt four-wheel disc brakes to their 1956 model 541 Deluxe--and they did, but it wasn't until October of that year. Yet it was Austin-Healey, one year before, who fitted their 100S with the same Dunlop disc brakes on all four wheels. But the 100S was a limited-production competition-based model, and the Jensen was a true road car. However, if production vs. competition doesn't matter, then Jaguar had them both beat with their beautiful C-type race car, which they built for the 1953 Le Mans, and in which they finished in first, second and fourth place." The article discusses others and concludes "it's clear to see that the Citroën DS was the first volume-production car so equipped, while Triumph's TR3 was the first volume-production sports car, and Jaguar the first racecar builder. Crosley is unquestionably the first American manufacturer, but there's little doubt that Lanchester deservedly gets to be crowned king."

I don't know why, but I'd also bookmarked this wikipedia entry on Maxaret (probably because I'd also bookmarked this entry )

However I didn't chase anything further on anti-lock technology but did find that Dunlop were, and still are, big in aircraft braking systems (admittedly I didn't bother to look for any other company in aircraft braking, past or present). The shields on aircraft brakes are primarily heat shields to protect the tyres - this amazing youtube video shows a simulated worst-case-emergncy test of the Airbus A380 Honeywell-Dunlop brake assembly - 125 MJ (35 kWh) of energy absorbed in 25 seconds !!!

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Re: disc protectors/splash guards/splash shields

Post by Brian-H »

A really geeky observation here :ugeek:

Looking at the Front brakes diagrams on Jag Mk 10, Jag Mk2, Daimler V8 250 - the Front brakes are almost identical across all 3 cars (to compare, for each link, right click, then "open link in new tab", then look at the diagrams one by one).

Jag Mk 10 Front brakes
Jag Mk 2 Front brakes
Daimler V8 250 Front brakes

Looking at the Rear brakes diagrams, since the Daimler V8 250 saloon is based on the Jag Mk 2, the Rear brakes on the Jag Mk 2 and the Daimler V8 250 should be the same.
But they're not, it's the Rear brakes on Jag Mk 10 which are more similar to the Daimler V8 250.

Jag Mk 10 Rear brakes
Jag Mk 2 Rear brakes
Daimler V8 250 Rear brakes

Assuming that these diagrams are correct, then the brakes all round on the Daimler V8 250 Saloon are more similar to the brakes on the Jag Mk 10 (no shields front or rear), even though the body is based on the Jag Mk 2. That also makes it even more strange that there are shields on the rear of the Jag Mk2. Is it a Girling vs Dunlop thing ?

Christopher Storey
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Re: disc protectors/splash guards/splash shields

Post by Christopher Storey »

I don't buy brake parts from a scrapyard !! - and that is who produced these diagrams

Brian-H
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Re: disc protectors/splash guards/splash shields

Post by Brian-H »

Christopher Storey wrote: Fri Feb 05, 2021 12:00 pm I don't buy brake parts from a scrapyard !! - and that is who produced these diagrams
Thanks for the contribution but times have moved on from justjagsuk , take a look at their homepage https://www.mytonautomotive.com/

I should point out that "trashing" a supplier in that way could be potentially libellous , read their "about us" page https://www.mytonautomotive.com/page/about-us
"With new owners in 2004, a new focus on the potential of the Internet was made a primary objective. A new Jaguar website was launched and we started to focus more upon supplying new parts (rather than only used parts) to our worldwide customer base, as a result we decided to shut down the scrapyard operation.."


Is there anyone else who would be able to confirm or refute as to whether or not the Rear brakes on the Daimler V8 250 are more like the Rear brakes on the Jag Mk 10, than the Jag Mk 2 .

JT7196
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Re: disc protectors/splash guards/splash shields

Post by JT7196 »

Brian-H wrote: Wed Feb 03, 2021 12:54 pm ^ you triggered some vague recollections of that - when doing the searches 5 years ago, I downloaded quite a bit of stuff into a folder :geek: and also bookmarked :ugeek: quite a lot - all on another laptop that's been carefully stored in the loft for the last 3 years. I took the previous content from the folder in that laptop, went back again just now and copied all the bookmarks onto this laptop.

As well as this google book excerpt and another google book excerpt I also bookmarked this article.

The latter mentions a 1949 Chrysler system, saying that it "did not incorporate a caliper clamping down on a disc; instead, they relied on the engagement of a pair of discs rubbing against the inside surface of a cast-iron drum". It also says that "the Indiana-built 1949 Crosley was first fitted with Goodyear/Hawley disc brakes on all four wheels. Unfortunately, these calipers, which were initially designed for airplanes, couldn't stand up to the repeated use demanded by the automobile, and thus proved troublesome". The article also says "For years, it's been widely acknowledged that Jensen was the first manufacturer to adapt four-wheel disc brakes to their 1956 model 541 Deluxe--and they did, but it wasn't until October of that year. Yet it was Austin-Healey, one year before, who fitted their 100S with the same Dunlop disc brakes on all four wheels. But the 100S was a limited-production competition-based model, and the Jensen was a true road car. However, if production vs. competition doesn't matter, then Jaguar had them both beat with their beautiful C-type race car, which they built for the 1953 Le Mans, and in which they finished in first, second and fourth place." The article discusses others and concludes "it's clear to see that the Citroën DS was the first volume-production car so equipped, while Triumph's TR3 was the first volume-production sports car, and Jaguar the first racecar builder. Crosley is unquestionably the first American manufacturer, but there's little doubt that Lanchester deservedly gets to be crowned king."

I don't know why, but I'd also bookmarked this wikipedia entry on Maxaret (probably because I'd also bookmarked this entry )

However I didn't chase anything further on anti-lock technology but did find that Dunlop were, and still are, big in aircraft braking systems (admittedly I didn't bother to look for any other company in aircraft braking, past or present). The shields on aircraft brakes are primarily heat shields to protect the tyres - this amazing youtube video shows a simulated worst-case-emergncy test of the Airbus A380 Honeywell-Dunlop brake assembly - 125 MJ (35 kWh) of energy absorbed in 25 seconds !!!
Hi , I was under the impression that Lanchester was the first vehicle fitted with Disc Brakes in 1904 !

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