Brake disk thickness

I took my under restoration 68 e type to a garage for the California brake and light inspection (prior to getting license plate).

But there computer didn’t have specs for my old car and they could not do the test because they didn’t know the minimum thickness of the brake rotors ( to see if they hadn’t been turned down too much).
My rotors have never been turned down but I need to prove that.

I looked in the original Jaguar manual and it lists rotor diameter but not thickness.

Does anyone know what the original thickness was and, more important, where I can find it documented for the inspector?.

9.8mm (3/8") is the minimum. It’s often stamped on the rim of new discs.

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IIRC, early cars were 3/8", later ones 1/2". Not sure exactly when the change was made, but pretty sure a '68 should have the thicker ones.

Yes. I’m trawling the Service Manual now; so far no luck.

Have any other California owners been confronted with this problem? And if so, how did they deal with it?

According to the Technical Descriptions and Specifications, “E” TYPE GRAND TOURING MODELS issuede at the car’s launch the brake discs were 11" in diameter and 3/8" thick in front and 10" X 3/8" rear.

New rotors on my '68 were 9.75mm (0.384") thick.
Minimum thickness stamped on them is 8.6mm (0.339")

George, here is a Jaguar Service Bulletin, L.26, Section Brakes, dated 6/1963 that should satisfy the inspector -

That covers the rear, but didnt the front rotors also change to 1/2" sometime around 67 or 68? Likely with the change from Dunlop to Girling calipers?

I was intreged by this requirement too, as I’ve never come across such a requirement in California before. This is what I found when I searched:

In California, a brake and lamp inspection is necessary to ensure that a vehicle is safe to drive and operate properly on the road. Brake and lamp inspections are required anytime an automobile is being retitled, which includes after a car accident or vehicle theft .

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Don’t know if they’ll accept a website but

https://www.stockwiseauto.com/centric-121-20000-disc-brake-rotor?fit_id=1224&Year=1968&Make=Jaguar&Model=XKE&gsID=pxf41616f1224

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Page 53 on this one:

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On this one, click on “More” to see the minimum thickness spec
https://www.onlinecarparts.co.uk/trw-11015373.html

The 7th entry on this page
https://www.bestpartstore.co.uk/jaguar/e-type/6841/10132-brake-disc

Wow, this is really confusing. About half of the above sources say 1961-68 rotors are 3/8 inch and half say 1/2 inch. Is this a typical “Series 1.5” issue about hermorfadites? (ignore bad spelling). I think my 68 has 1/2 inch front rotors as most things in my car are more Series II than I.

Does anyone know what happened with brakes in this transition year?

A Series 1.5 is considered by many to be primarily a Series 1 with some features of a Series 2. If what you have is a true Series 1.5 factory braking setup, you should have Dunlop brakes front and rear, with 3/8" thick brake rotors. This is the case for my '68 Series 1.5. I don’t believe the brake rotors went to 1/2" thick until Series 2, with the Girling brake setup.

I’m certainly no expert, but I am sure someone will speak up and point out if I’m wrong. :slight_smile:

My original SII rotors are .5” thick.