OK so after 12 or so years of my rear discs looking dodgy I am going to drop the subframe and change them. The part No for an 89 V12 is JLM 730 and the description is Disc Damped.

More common and cheaper are discs C26779 Disc.

What is the difference - if any and could I fit the cheaper ones without problem ? Anyone any experience of fitting the C2779 discs to an 89 or later car ?

 

I've always used the non-dampened brake discs. No problems at all

Cheers
DD

 

Agreed.

1989 is way past the Dana rotor oddity, and anyway, now the rotors are multi fit, down here at least.

Never used Genuine, so in the dark there.

 

EBC makes performance vented and slotted rotors for the XJS, I have these on the front, couldn't order (at that time) the same for the rear. Consider vented rotors they'll last longer then a basic oem one.

 

Keep the updates coming, I am interested in how you get on.
I will need to do this one day.
cheers

 

Vented on the front, standard.

Vented on the rear, NAH, too much work involved. Caliper spacer, reshaped bridge pipe, and then exhaust clearance issue for that bleed nipple that is just ":kissing" that over axle pipe now. Looked at it waaaaay back. Stayed standard, and things are just fine on ALL the Inboard braked cars. I dont track the car, never have, never will, peak hour stupidity is tough enough, so maybe thats the difference. Drive them HARD, hell yes, but stopping has never been an issue.

Longer life, doubt that seriously, they wear as designed, based on the pads that are chewing away at them.

The standard ear rotors in the XJ12 (Sir Arthur) were changed at 330000kms, and they were the OE sandwich style, and very sad. Car now has 600000++kms and the replacements are just fine. 3rd set of fronts now being consumed since the car was new.

My XJS, new all round at 130000kms, just because I had them, and the rear cradle was out for output shaft seals. Now at 300000kms, and all 4 are just fine.

 

Improved damping serves to reduce brake squeal. So no big deal considering I've had no issues with my older style and the fitment is the same.

 

All good on the brake front. Many thanks to your guys - the standard discs went on a treat. Working on the handbrake is so much easier with the cage down. I have changed the handbrake pads about 6 or 8 times because always one pad seems to drop off within 6 to 18 months. Whilst I have tended to assume it was down to useless manaufacturing quality regardless of the cost paid or the brand lable on the box, I saw how far the arms on the plate were distorted so that fore each pair one of the pads would have continually rubbed so maybe I was too critical. Anyway each calliper went on and off about 6 times until I was entirely happy that the plate was springni back each calliper arm so that the pad on that side just cleared the disc. Getting vision like this is just not possible with the cage in place. One is thankfull just to get the ends of the arms on the plate into the hole in the calliper arms as you tighten up the pivot bolts !

My wife was hors de combat whilst the suspension was down. Shifting that assembled cage across a drive that is not smooth but block pavoirs was real tough alone. I did not have the rear end up high enough so I dropped it and then it had to come out sidewards. I used two little 2 ton trolley jacks for the sidewards move but the wieght was so great and their wheels so small that frequently it would not budge and I had to use the 5 ton jack to lift it and reposition them. Plus it always wanted to fall forwards or backwards, which meant I could not use the large jack alone for the sideways movement, And the garage is too small to get the suspension out sidewards. If ever I have to do the job again and I think I probably will, I will make up two dolly trolleys with large diameter caster wheels and a wooden cradle on top for the aluminium hub carriers to go into.

I have a large bore stainless steel exhaust. If I had known how much of my life I would spend adjusting the thing so it does not hit virtually everything under the car, I would never have bought it. Certainly you can get it so that in normal driving it is not fouling anything but go over THIS sort of a bump and it hits that. Move the XX side a little to the left and it is all good - on THIS sort of bump. But now, when you go over THAT sort of a bump it starts hitting the YY side a bit. The cage is disaster area for it. It is spoilt for choice for things to hit on all sorts of bumps. I think I was quite happy after about two iterations that only the biggest bumps cause any clanking. I have had it on the car since 2004 and so it has been good value, but it must have added 3 hours to this job at least.

The real bad news is that I have broken the end off the speed sensor in the diff !!!! I have posted about that in the relevant thread. The shimed gap should be 10 to 20 thou. But do not remove it when dropping the cage, like I did. Leave well alone ! Disconnect at the terminal block in the boot. See my reply elsewhere for more details.

Anyway - once I get the speed sensor done I can pack for the holiday. I will post up something later.