I figured I put an image of a STR SC lower control arm with new poly bushings. (Thanks to Martin for selling me his set) These arms will go on my STR in the near future.

 

Hi there! Does anyone knows if the STR uses the same master cylinder as the normal S Types? In most of the aftermarket sites the only difference I can see is if master cylinders have DSC or not...

 

Have you looked in the JEPC (Jaguar Electronic Parts Catalog)?
It's free on this site and has a lot of good exploded diagrams too!
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Thanks Tbird6! I´ve downloaded the JEPC and it seems the master cylinder is the same, no matter if it is a STR or normal S Type...
Regards

 

That's good to know as the rest of the brake system does have differences.
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Hi Joe,

If i've understood what's been said in this thread correctly, the STR 4-piston calipers on the rear already accept 28mm wide rotors, and it's only this spacer modification on the e-brake caliper that's needed to get a 330x28 rotor on the back of the STR?

 

You'd need to space out the caliper, I reckon, as the STR (Brembo) rear disc is only 15mm (solid). Beyond my knowledge whether it's wise/safe/etc.

 

I just popped into the workshop & had a look





Yep the narrowest part of the caliper is only ~22mm, so yes a spacer would have to go in the middle of the caliper.

Reading back over this thread, I realise why I got confused, Joe is using a rear Brembo caliper from a 2011 Camaro (post #18)

Ummm....

Well the spacer on the e-brake caliper seems to work OK to accommodate a 28mm wide rotor, why not do the same with the main caliper, it's a split design, would just need longer bolts & new crossover tubes...?

 

I think the XKR Brembo rears use 330x28mm (vented) discs. Not sure which years etc. 2003, I think.

I'm not sure what's "wrong" with 15mm solids on the rear, but that's another topic!

 

As some of you may know, I abandoned using S-type rear suspension and went with a combination of C6 Corvette and Camaro parts for my hub carrier, hubs, brakes and am building custom a-arms to mate the parts to the sub frame. (Posted in other threads.) Jag-V8 does have a good point on the STR. What is wrong with the solid 15mm rotor? Perhaps less heat dissipation than a vented rotor? Unless you are driving your STR on the track or heavy duty street work and you are crazing and cracking the surfaces of the rotors, then solid will stop as good as vented.

Before trying to go to 28mm wide rotors, You should calculate where you would want the added thickness, in-board, outboard, equal spacing front-back from the existing centerline. I don't think there is much clearance between the outside of the rear Brembo and the wheel. If you stick all 13mm (1/2") outboard, I bet the caliper will hit the wheel.
If it hit, you will have to back space the calipers until they clear.

Joe

 

Call me crazy but yes i'm going to take the XJR out on the track. Just club-level SuperSprints for fun, but it means I do need proper brakes on this car that will not fade out after a few laps.

I can't think of any modern >400HP performance vehicle that has solid rotors on the rear (I'm not familiar with US muscle cars, so maybe i'm wrong there).

The rather limited options in rotors for these Brembo equipped cars has driven me to look at getting some custom 2-piece rotors made for the fronts as a minimum. If i'm going down the road of having rotors custom made, then why not fix the rears as well?

No question a thicker ventilated disc will be better than the solid ones.

I know I could pretty much bolt-on the Alcons from an XKR, but the SuperSprint regulations mean that I can't increase the rotor diameter. Well I could, but that would put me in the Unlimted class, up against 1000HP Supra's & Skylines. Which wouldn't be much fun.

I think you might be right about the clearance between the caliper and the back of the wheel, there wasn't too much room to play with.

I notice that some other makes have ventilated rotors starting from a thickness of 20mm, the rears wouldn't necessarily have to be 28mm thick...

 

If you plan on starting to participate in "track days" the first thing I would do is take a look at changing you disc pads. Go to you favorite pad manufacturer web site, (Hawk?) and purchase a set of pads with a pad compound recommended for track use. What this will do is reduce or eliminate the fade you speak of. The trade off is that you will probably quickly wear out the current rotors on your car. (But this will give you an indication of what you will want to do going forward.) Driving hard on a track is really hard on rotors. You almost have to consider the rotors a consumable every 4-5 events on the track. Doesn't seem to make much difference what high quality brand you purchase, they all seem to wear faster than you'de expect. As you probably know, high speed breaking generates a lot of heat. The rotors suck up this head and try to dissipate the build up a quick as possible. (One reason vented is better). After your first track day, you may find out that you may boil your brake fluid and have to upgrade your flexible brake lines, and/or go to a synthetic higher temperature brake fluid. Then you will start looking into adding ducted air to help cool the rotors. Often brake fade is due to the brake lines getting too hot and expanding. Sometimes it take numerous track days, as well as talking to other drivers to figure out all the unexpected things that go wrong driving your car so hard for extended periods of time.

 

Thanks Joe,

I'm well aware that the OEM pads are not up to the track, but sadly Hawk don't make a pad that fits the front caliper of the STR/XJR (rear yes, but not front)

Don't know if you saw the other thread Brake Disc & Pad Options - Brembo STR & X350 - Jaguar Forums - Jaguar Enthusiasts Forum

Porterfield make a dedicated race-spec pad, but that would mean having to change the pads at the track, which is do-able since the Brembo's allow you to change pads without having to take the whole caliper off the car. But i'm not quite ready to go to that level, so i'll be using Yellowstuff pads as a compromise to begin with.

Brake fluid is obvious. The factory brake lines are already braided, but with the age they might well need replacing, this remains to be seen.

Anyway, my main reason for looking at floating 2-piece rotors is warping, i've warped OEM discs twice, and i'm sick of it. Actually i'm sick of the shake through the steering wheel because of warped discs, it's unbecoming of a Jaguar. A fully floating 2-piece rotor should solve that issue. TBH I have no faith in any of the "aftermarket" 1-piece cast rotors not warping either.