420G Brake servo decal

Yes I think we have definitely identified the correct secal for the Girling servo for the 69-70 XJ6. I’m just waiting on JDHT to confirm, as I still need to make a few assumptions, I guess there is a possibility there was no decal at all. Judges are happy to assume it’s the same decal as the same servo on the XJ6 of the same year. Will let you know as soon as I hear from JDHT. I have already ordered the decals :blush:.

What I find interesting is the orientation of the decal, seems counterintuitive to me. I would have turned it the other way round. The red car in your post seems to have it in the correct orientation while the black car has it how I would have expected, but, is not correct.


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Thank you for sharing their results, I don’t know if it’s such a good idea to add something again, but the XJ manual (so drawn before release) and a launch car that had the bonnet up for the camera both show no decal as far as I can tell. Other stickers seem to be there.

I think you are correct I shouldn’t add it, but, it comes off as easily as it goes on! If JDHT consulted the service manual that I have, it doesn’t mention any decals anywhere, so that’s not a good a good reference. Also, I do not believe that the 420G JDHT has is an original unmolested example they have had since brand new, I think it has been purchased from the general public, so, again not a definitive reference. It does surprise me, however, that there would not be a decal, given the Dunlop had two and the XJ6 has one…if was important to provide information on the brake fluid for those vehicles, why not the 420G? But, also equally surprising there doesn’t seem to be a surviving remnant of a Decal anywhere to be found. Not surprised the judges expected a decal.

There’s one drawing where there’s a decal on the washer pump but not on the booster, I think they drew what they saw, but it’s not the best evidence is it.
And even if the exact XJ sticker is known well, did the 420G get the same sticker or just the same booster?

Probably need some period photos to be definitive

or a totally unmolested original

I have had mine 25 years but got the booster OH about 10yrs ago

I will check my old engine bay pics, while I cannot guarantee it was totally original, I have good reason to believe it was, still have not checked my booster collection


If you are able to definitively prove your “sticker” situation" is “correct”, will the Judges reallocate the deduction and give you 100 points ?

I personally belive the XJ6 and 420G booster are the same, would have come from the same “supply” but would have come in batches. Some may have had no sticker, and there may have been sticker variations

In addition, many MKX and 420G have been “upgraded” to the Girling system, I believe this was done by dealers due to a shortage of Dunlop parts

Is there a Bulletin on this ??

No mention of the Girling system in official MKX-420G Service or Parts Manuals that I can see

closing question; At what point are stickers and decals placed on parts?

by suppliers or Jag assembly line. I favor this option as most likely

Hi Tony, no the judges decision is final, I don’t mind losing the point, it’s more if I can correct it I may as well. One extra point would only increase my score by 0.04%, I lost 16 other points. I don’t hold any ill feelings towards the judges, I’m grateful they donated their time and expertise to be a concours judge.

I wonder if there is a JEC concours judge about who may know the answer.

Yes the bulletin has been posted, but, nothing about a decal of course.

I don’t know when the decal is applied, at Girling or Assembly line. I guess if there are other marques with the supervac 100, they might have the decal.


So shouldn’t there be a Dunlop sticker… not Girling? The XJ has Girling brakes and the sticker has little to do with the booster other than convenient location, as the hydraulic system determines the fluid.

Steve, Tony, David et al.

Ref post #10.
The Girling fitments catalogue indicates the same Supervac 100 servo and same Girling part number used for the 420G 1968 onward and the XJ6 both RHD and LHD till about mid 1970 and notably the XJ6 LHD thru till at least 1972.
Also, Thorley’s book and the Technical bulletin cited by George Camp many years ago show the official change from the Dunlop P90 to the Girling Supervac 100 occurring in April 1969.

Yes, it seems that some earlier 420Gs before April 1969 were fitted with Supervac 100s.
The Dunlop, “DO NOT OIL” sticker," was only fitted to the Dunlop P90 servos. Albeit, before the official notification of the change.
However, in late 66 thru 67, Girling MCs were also fitted as conversion kits to those same Dunlop servos as stocks of the original Dunlop MCs had, by then, ran out. Presumably before the Dunlop servos ran out.

Back to the labels:
Actually, I think I was wrong in an earlier post, and the correct label, (when applied to the servo), should reference the Girling Amber/Colourless fluid; size of that label is 4-1/2 x 1-3/4" approx.
Best shown for size only on the 420G, currently on Carandclassic image.

My understanding is that the Girling Green fluid as indicated on the smaller 3-1/4 x 7/8" labels on the XJ6 servos from 1971 onward, was not actually available from before 1971.
(see Impart spares bulletin from Sep 1971.)

Here is what I think would be the correct label for David"s 1970 420G based on all of the foregoing:

Someone out there, knows for sure. Please step forward… LOL


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My 69 XJ specifies Girling SAE J1703 on the air filter sticker that lists all fluids. Not J1703A or J1703B.
In the 72 XJ maintenance sheet they ask for Castrol/Girling Amber fluid, J1703A. Fwiw.
I have the J1703A Sticker for now although it didn’t mach the shadow on the chromate.

All very interesting Nick, somebody must know! The person that is widely regarded as being the most knowledgeable on Mk10/420G in Australia is quite emphatic that there were no labels at all.

I should try and reach out to the JEC and see if I can contact a concours judge there, I am disappointed the response from JDHT was close to useless.


So after a global discussion (AU/UK/US), and particularly from The Coventry Foundation in the US, this is what I have come up with, the same sticker that appears on the servo of a Ser 1 XJ6, which has been confirmed from press photos and various surviving stickers, that was purportedly applied by Girling.

The only other option is no sticker at all. It would be unusual to suggest that it would be necessary to provide brake fluid information for the MkX/420G with Dunlop servo and for the same Girling servo in the XJ6 and not for the 420G. Happy to be proven wrong. It comes off as easily as it went on!

Many thanks to all those who contributed and again especially George Camp at The Coventry Foundation.

Thanks for that info.
I’m interested because, like you, I’m trying to keep everything to factory original stock.
And in the case of the change from a Dunlop to Girling servo, either as a factory fitment in the April 1969 420Gs onward, or as a factory sanctioned dealer replacement to the earlier 420Gs and 4.2Mk10s, my question is:
Where is that picture from?
I ask because the servo has the “Green” fluid label, which as I posted recently, according to the Impart bulletin, wasn’t available before 1971.
My understanding is that the amber fluid was introduced in 1968 or so and therefore, technically the “Amber” label would be correct for the late 420Gs and indeed the earlier Xj6s.
Perhaps, George would have some insight into this.
And you thought this subject was reslolved… LOL


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Nick, I have done a bit of reading and I believe the US had different rules regarding brake fluid. I don’t think the Green fluid was allowed to be used in 1970. As I don’t live in the US I’m not sure the spec you posted is relevant to me. I didn’t want to get too deep into that topic!

Noted, and that will lead me down the road of yet more research!
BTW, I did find and old Motors Magazine road test from the UK of a 1969 XJ6 and can see in one of the pics that there is a label on the servo, but can’t make out what it says.
I’ll try to scan if helpful and it’s within the Brooklands books publication; XJ6 1968-1972, which is basically a reprint of the many road tests done at that time.
Fascinating stuff indeed and one day, someone will indeed step forward.

Nick, there are from Harvey (1991), they are hard to make out except for the shape. The other stickers all have different shape (the amber one for example). Always happy to be proven wrong.

On a separate note, out of the same book. I have always been slightly unhappy with the alignment of the boot lid. It’s much better than this press photo, so I feel better now. Now if only I could eliminate all wind noise.

The car at the top is not an early car. I think it’s useless here. Even has the AED and so on.
The one at the bottom is a VERY early car, with three clips on the air filter box, rubber pipes all the way on top of the radiator, early brake reservoir, clip for the one way vacuum valve welded in the early location, etc. Pretty nice.

Here is another early XJ, unfortunately I can’t give credit but it might be from a french magazine? Note it too may not be entirely original but definitely 68/9 and in period.