Hey guys,

So, with brakes, my X308 has yet again managed to 'warp' the discs so I'm looking into new discs.

Oddly, the 325 mm discs from TRW are cheaper than the standard 305 mm ones. Is the 325 setup then the R brake job or simply the same ATE brake caliper as the 305 with a different mounting bracket?

Cheers

Damien

 

I am working on converting to the 325 R's and initially the difference is obviously diameter and a bit thicker. I can tell you the discs studs mount the same. The R caliper is a different mount height wise and has dual pistons as opposed to a single on the 305.

Here's an old link for rotors I had...https://www.jaguarforums.com/forum/x...rotors-123561/

....and one for the R calipers, member Luc is very experienced with this and the photobucket link I think will help you.... https://www.jaguarforums.com/forum/x...wanted-128967/

 

After googling, the 325 mm are not R brakes but just later brakes.The R package brakes are a lot bigger with multi pistons. The 325s have a single piston still...

 

As a general rule, 305mm are XJ8, 325mm are XJR, 355mm are R1.

 

the 98MY XJR's had the smaller 305 rotors up front, it was stepped up to 325mm in 99 around the 853xxx vin I think. 355(?) is the Brembo/R1 front rotor.

My XJR takes 325 up front, and has a single piston floating caliper.

 

Thanks for confirming. So either the caliper is different or the bracket. I doubt both for some reason. And think the bracket will be different.

Can you still run 16" rims?

 

I think I've been told 17's are the smallest that can be put on the 325 front setup, haven't tried it though.

I'm only seeing the PN for the caliper+carrier assy for the 305 and earlier 325mm calipers, while the F08336-on lists caliper and carrier separately. However the f08336-on caliper+carrier assy PN's line up with the earlier ones - 305 for non-SC, 325 for SC. Going off that assumption, for the caliper and carrier listed separately, the same caliper PN is used on the 305 and 325 options, while the carrier PN is different. That kind of makes sense since Rockauto lists the same brake pads for the front whether it is 305 or 235 rotors.

Using this for reference, usually follows Jaguar factory part numbers accurately: https://www.jaguarclassicparts.com/u...-caliper-front

 

If you read the 2nd link I provided, the R's won't fit in a 17 and only certain 18's will fit stock. The clearance of the caliper is the issue.

 

As stated, I'm not asking about R brakes. Just standard 325 mm single pots as fitted to later 3.2, 4.0l engines instead of the 305 mm brakes.

 

So if you go to the 325's, you'd need to know clearances to fit the (R or not) caliper which has longer legs for that clearance. That's what it talks about in the 2nd link I provided which has additional links provided by Luc.

 

My R has the 325mm single piston discs/calipers. They still warp like a SOAB compared to the 305mm that are on my XK8. Having not tried it I would think if you simply replaced the front calipers and the front discs with the later 325mm set up you should be golden, I honestly don't think it is gonna make a big difference aside from maybe a slightly cooler disc because of more surface area but braking will be the same as the pads are the same.

 

My 305s have warped 3 times already. Once a pair of cheap brand discs. Once a pair of ATE originals. And then the last time some original Jaguar ones - which were also ATE. Hub is straight. Caliper fits correctly and isn't warped...

The 325 mm can still brake better due to the position of where the pads contact. Remeber leverage... It may only be 10 mm further outwards (radius) but that can be enough to up the stopping force - larger surface area for a pad to contact before touching the same area again. Friction = speed reduction. Warmth = reduction of friction. That added to a lever a little longer and the brakes can stay cooler. Thrus my little 3.2l won't need the same braking as the larger engines

 

All it says it 'direct fit'. Obiously. But not what parts are needed. The photobucket links also don't work Still thanks for that link, though it only says what Jaguar Classkc Parts says. Though it does not say: if the calipers are the same or if the bracket is the same. Going by common sense and seeing that the bracket already sits close to the dksc, that will need to be replaced...

 

That's quite a history of warped rotors. If its not driving style; then check your calipers and pad wear for even wear/stiffness.

My 98xjr had braking issue (305mm disks), directly related to played calipers and enthusiastic driving habits... Prompting an upgrade to R1 calipers and rotors.

 

Apparently Luc has deleted or moved them in photobucket, but in the same thread the last link in post #7, he explains in detail the part #'s.

 

No, it was photo bucket who cancelled all pictures linked to other sites

 

Hello, rekindling the ol' 305 vs 325 brakes. Proud warper of discs here, 305s (Mintex). I did read all the posts (and recommended links) but I don't seem to find the answer, maybe you guys could please clarify...
So case in point is a 1998 x308, vin starting with 856, 17" Celtic Alloy wheels. My questions are:

1. Would the 325 disc fit the wheel ?
2. Do I need to change the calliper (in relation to the disc and/or wheel) ?
3. Is it worth moving to performance parts such as this one or this one?

Many thanks for your patience and help!

 

...Again, I am not the most tech-savvy guy here, any help would me much, much appreciated ...

 

I can't remember a single other thread about this, I am afraid you might not get here what you are looking for.

 

I can say the stud pattern is the same, I have 325's waiting to go on mine when I get my R rotors refurbed and I did put them on the spindle to check clearance with my Penta wheels.
The existing caliper won't fit, it doesn't have long enough legs.
Performance rotors are a personal choice, just remember there are cheap and quality performance. Me, I went with what Jag specced for the R rotor.