Hi Guys

Nothing but Problems!

With 'Cherry Blossom' almost at the stage of being mobile, I've had a few problems to overcome in the Hardware department regarding the Brakes.

One Firm sent me the Wrong Size Flexi Brake Pipe Retaining Nuts

While another sent the Wrong Flexi Brake Pipes

Then if that wasn't bad enough another one sent me Brake Pads to fit a Suzuki!

So seeing as Lightning doesn't Strike Twice! I ordered a Set of Brake Pads from another Firm, who had an illustration of these together with the dimensions on their Website.

You are probably quite familiar with these and may even have them on your own XJS

As they are the same Thickness all over the Pad and have a couple of Slots cut in to assist Heat Dissipation and I myself have been using this type on all my Cars.

The Illustration confirmed to me that this was exactly the type they were going to send.

So What could possibly go wrong?

Instead of the Pads with the Slots cut in, on a Pad of an overall Thickness:

What I got instead was a Pad that was Flat with No Slots cut in for Heat Dissipation which also Tapered at the Top and Bottom of the Pad.

Which meant less Surface Area in Contact with the Rotor

Although they were supposed to be a Compatible replacement for a Jaguar part number JLM 1510.

What do you think Guys

Keep them or send them back?


No Slots for Heat Dissipation and Chamfered at each end, which seems to me less Pad Area in Contact with the Rotors.


Not as per the illustration on their Website


To me its the Same as ordering some BR7EF Spark Plugs and instead they send you anything that will screw in the Hole.


But the Part Number is: JLM 1510 which is the right Part Number.

 

If time isn't an issue I'd send 'em back and get what you wanted.

Over the years I've had more than a few problems with vendors advertising one thing and sending another. Very annoying. Some disclose in fine print that they'll be sending whatever they want to send; others don't

Cheers
DD

 

OB,

Are they a known brand for UK supply such as Mintex, Ferodo, Pagid, EBC etc? If not, and as mentioned, unless you're really desperate for time, I'd send them back and buy a known brand. I'm a bit fussy on safety components and wouldn't fit a non-recognised brand to my 145mph car.

Cheers

Paul

 

They are absolutely fine OB. Chamfering like this is standard practice on most upmarket pads. They look like Brembos to me. All will be well
Greg

 

The pads look fine but I would be more concerned with the composition of the pad , maybe worth asking what that is .

 

Exaxtly

And technically it doesn't matter if the pads were from a Suzuki, a BMW or what ever. The brake system is used in many cars. For example the rear calipers are used innthe Volvo 240 as front calipers. You just need to make sure the brake system (ATE, Girling, Bendix, Brembo, ...) is the same.

I've got BMW pads in my XJ8. My C30 had pads from Mazda and my old 960 I had years ago got Golf pads. One pad type will fit hundreds of different cars, as the brakes are made for ONE car. The brakes are made as a kit and the car manufacturers by the kits.

Jaguar seems quite keen on ATE and Girling (as far as I cam tell).

 

Hi Doug

These are Brembo.

One of the Top Makes but the Supplier that I got them from, shows them as being Slotted with an Overall thickness from one end to the other.

And I checked all the dimensions against my existing Pads with a Caliper, to make sure of what I was getting.

Apparently the End Chamfering is to reduce Pad Chattering (which has never bothered me)

But this Comes at a Price of less Brake Pad in Contact with the Rotor and cannot believe Pad Chattering is more important than that.



The Pad on the Left was sent to me in error and very obviously isn't the one for an
XJS.

The Pad on the Right is the Type that I normally use, though it is looking battered and bruised as I had to get it out of the Caliper with a FBH and Chisel



This One is the Brembo which has Chamfering at both edges and not what I thought I was getting, as the Suppliers Illustration shows them as being Identical to the Pads that I want to replace.

So it looks as if we could be Starting a New 'Oil Thread' with this one.

The Chamfering is about 15mm each end, so unless I'm much mistaken that's about 30mm less Pad in Contact with the Rotors when you put the Anchors on.

Maybe they are made of some special High Tech Material that Compensates for that and also does away with the need for Slots for Heat Dissipation, I don't know.

Does anyone know?

I would have thought that Surface Area in Contact with the Rotor would be Paramount and I am going to take some convincing that this is not the Case.

Opinions please Guys

This is a new one on me.

 

The chamferring will wear off really quickly. Most time, afaik, the pads have a different hardness from start to finish. The brake in phase having a softer compound for quicker wear and then gradually getting harder to be more durable.

Also, you never actually brake with the entire surface. It just looks like that. That is why many brake systems specifically made for one car (these are super expensive cars with ceramic/carbon systems rather than the peasant versions we have) habe multi piaton calipers with each piston having it's own pad.

I think you're worring too much OB. Pad surface isn't as important as for example piston pressure. What good is it having huge pads if they can only be applied in a small area with lots of force? We have 4 piston calipers working on a small pad. More than enough surface area to stop the car quickly and effectivly

 

Daim

You've got the Wrong end of the Stick

What we are talking about here is the Design of the Brake Pad rather than the Make, as my Original Brake Pads did Not have any Chamfering but they did have slots.

The design of my Original Pads are produced under various Brand Names and as far as I can tell all perform as good as each other.

But these New Pads have Chamfering, which I've never come across before, so I need to know if they are just as efficient at Stopping the Car.

As the Chamfered edges which are supposed to cut down Pad Chattering, come at a price of having less Surface Area in Contact with the Rotor.

Maybe they are constructed from a Superior Type of Material that Compensates for this but I don't know the answer to that one at the moment.

 

Since I've got Brand New Calipers Piston Pressure isn't the Problem, so lets see what others think.

 

Yes I agree with you on that one but not sure the suppliers would know.

 

Hi Paul

They are Brembo one of the Top Makes, so I am very happy as far as that is concerned but would you be happy fitting Pads that have Chamfered edges at the expense of Contact Area with the Rotors?

I'm hoping Ronbros chimes in on this as he's probably had experience with every type of Brake Pad on the Planet.

 

Normally I would agree with you but then we'd both be wrong.

 

Hi OB,
I understand your concern and agree to a large extent with PJTS regardingthe importance of safety items like brakes.

Despite the previous comments I would not hesitate to fit those pads, I will be very surprised if the braking system isn't fine with those.

As you state Brembo are a good brand with superb reputation.

Finally, like you I Am not a mechanic, and whilst I have tackled moderate jobs in younger years I now lack confidence to tackle anywhere near as much as you, despite that I managed to change front pads on my xjs, fairly easy job, in the worst Case if you are still unhappy after fitting you could always replace with pads to your precise requirements

 

Guys
The OEM brakes are one of the best features of the XJS. Until brake fade occurs (ie the inability of the pad/disc combination to generate a heat gradient between them and thus convert kinetic energy to heat) the pad area does not affect braking. It might not even then if the fade cause is not pad-related. All modern Jaguars have FAR smaller pads than our XJSs.
Even with standard discs and pads I have never experienced brake fade even with stops from three figure speeds. At UK speed limits, or even those limits plus 50%, you will never experience fade unless you find yourself racing Lewis Hamilton down the Stelvio pass with the Devil himself chasing you both. Under these circumstances ANY brake system will fade.
Furthermore, brake pad material is far more efficient than it was even 15 years ago, let alone when the brakes were first OEM fitted in 1975. There is absolutely no danger in, or downside to, fitting chamfered pads to your XJS. If you are worried about fade you can always select a harder compound from the aftermarket, but at the price of greater pedal effort when the brakes are cold.
Here is a link to the engineering science behind braking, in case anyone is interested in going into it further:
Engineering Inspiration - Brake System Design Calculations


Greg

 

I agree that Brembo is a good brand and that chamfering is of no concern.

But, still, if you specifically wanted slotted pads, and the vendor sent something different than advertised, then send 'em back !

Cheers
DD

 

I would use the pads. If you you think about it a slotted pad has less surface area than non slotted. Like stated before we have better quality materials these days and heat won't be a problem unless you are racing down mountains at hi speeds

 

I'd put those pads in as they are.


If you want to be academic. What is lost by chamfering is gained by
no slots!


As Greg says, unless you are driving at max, the full 145 Mph and braking from there, you will feel no difference.


When I did the front pads of my XJwuzza 6, I do not recall slots or
chamfers. But, cleaning the ways in he caliper had to be done to get smooth movement. And a bit of a grind on the pad edge as well. Not much. Lubed carefully. And the "goop and tin on the pad backs as
squeak suppressors.


I did omit the springs on he pins by accident. So far no ill effects.


No esoteric brand. Just the well known Raybestos!!


But, academics can be fun. or merely delay progress.
Carl

 

Not sure how others websites work but just an FYI, when ordering parts from our website you will find the part numbers are as below:

Plain number - Genuine Jaguar Product
Number ending with # - OEM
Number ending with * - Aftermarket
Number ending with K/U or alike - Usually an upgraded version

In this instance you'll see on our site that the OEM are indeed slotted whilst the aftermarket (in this case mintex) are not. Both of which we have been selling successfully for many years and are covered by our usual warranty.

JLM1510 Brake Pads Search Results here,.

 

OB,

I'm enjoying this debate as it's opening my eyes to some views on chamfering, not something I'd really considered before!

Having now heard that the pads are from Brembo, an extremely well-regarded supplier, I would fit them. My reasons being:

- Brembo are very good. If they think that supplying pads chamfered is appropriate, then that would be fine by me

- Greg is absolutely right. No-one can accuse the front of an XJS as being under-braked in standard form. I still find it fascinating that the XJS front caliper is really almost over-engineered compared to many modern high-performance vehicles

- Chamfering (as with slotting) does seem to be an industry approach to the reduction of squeal and pad deterioration in certain brake systems. See below from EBC website:

...the chamfers have several benefits.

Chamfers prevent tip drag which causes pad areas not supported by the caliper pistons to drag as the backplate flexes by microns under braking. Tip drag leads to glazing and squeaky brakes mid life.

Chamfers also re-align the stresses in the pad surface along the angled faces of the chamfer to reduce the tendency of the pad to lift at its edges. Rather like the ropes on a tent peg hold better because they are at an angle whereas when you want to remove a tent peg you pull it vertically up and it comes out of the ground easily.

I think the one thing that would make me most comfortable is that I just can't see Brembo doing it without good reason. Despite the potential concern about not having max pad contact area from the outset, it may be that as EBC mention, it's actually preferable this way for teh overall efficiency of the life of the pads.

I'd fit them, but as always with XJS pads, make sure that you have good clear fit on the shoulders of the caliper. As many of us know, tight pads on an XJS can lead to all sorts of problems including stuck pistons, jammed pads, warped discs etc.

Paul