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Re: Wanted XM rear rotors
Posted: Sun Dec 24, 2023 9:45 pm
by XMdownunder
Thanks dieselman I will purchase available rotors asap I should not have let them wear down to 5mm. Regards
Re: Wanted XM rear rotors
Posted: Mon Dec 25, 2023 3:50 am
by DownUnderXM
Dieselman wrote: ↑Sun Dec 24, 2023 8:16 am
I did see the Rp change for 2.5 Td, to the same as the V6 disks, but checking part numbers gives only 224mm disks, even Ate, who make the calipers.
I suspect lack of demand has caused supply to be curtailed.
The disks and pads changed to larger ones, so given that obtaining 232mm disks doesn't appear to be an option, simply fit the 224mm disks and suitable, slightly smaller, pads.
The 232mm disks are 4mm additional radius and the pads have additional friction material which gives the friction material increase of 200sq.mm.
It is dangerous to fit larger pads and smaller disks, as when the pads wear down the friction material overhanging the edge stops them being pressed against the disk.
Assuming the larger pads are available, if one really wanted 232mm disks, obtain a pair of 251mm disks and have them turned down to 232mm.
Edit:
I've checked the pre and post Rp7475 change and the pads have different part numbers, but the service replacement part numbers are the same.
When looking online the pads have the same size of friction material and the same manufacturers reference numbers.
The trailing arms and calipers are the same, so it appears the only change is the disk size.
My thoughts are to fit what you can readily obtain.
Thanks Dieselman, you've neatly summed up the situation!
Stephen & I both purchased ES9J4 XM hatches, which both came with 232mm diameter rear disks. However, we have both noted a wide lip on the rotors (approx 4mm), proving that they were fitted with pads made for 224mm rotors. Replacement rotors (apart from larger wagon units) are all 224mm, and the pads all fit this smaller rotor.
So Stephen, your course is clear - pick your favourite brand, and order the 224mm rotors (and presumably matching pads). They fit and they work properly, and there's no other option. Re. my rotors - I was teasing, I really did not expect you to want my worn-out, rusty ones!
Season greetings to all on this forum - a unique and valuable resource, doing a mighty job of helping to keep some very special cars on the road.
Re: Wanted XM rear rotors
Posted: Mon Dec 25, 2023 8:39 am
by Dieselman
DownUnderXM wrote: ↑Mon Dec 25, 2023 3:50 am
Stephen & I both purchased ES9J4 XM hatches, which both came with 232mm diameter rear disks. However, we have both noted a wide lip on the rotors (approx 4mm), proving that they were fitted with pads made for 224mm rotors.
Apologies, I hadn't noticed your comment from your ealier post:
DownUnderXM wrote: ↑Thu Dec 21, 2023 10:58 am
Careful inspection (and measurement) of the old 232mm rotors has shed a bit of light - my old rotors have a wider lip than normal - actually 4mm on each side, so the rotor is effectively 8mm wider than required by the pads. Perhaps the larger rotors did have slightly larger pads supplied at the time, which are also not made any more?
Obviously the original, larger pads haven't been available for some time, hence your car having a 4mm lip on the larger disks.
DownUnderXM wrote: ↑Mon Dec 25, 2023 3:50 am
Season greetings to all on this forum - a unique and valuable resource, doing a mighty job of helping to keep some very special cars on the road.
Members from around the World's input is valuable, without members being prepared to check items, report findings and feedback we would all be lost.
I enjoy reading input from Global members as they have different experiences to Uk ones.
Thank you for Your input.
Have a merry time of what's left of Christmas day, you are closer to Boxing day now, than opening your prezzies.
Re: Wanted XM rear rotors
Posted: Tue Dec 26, 2023 2:09 am
by XMdownunder
Thanks dieselman I got some brake parts in my stocking no better way to spend boxing day in the shed under the back end of an XM. Its too flaming hot to go to the beach anyway.
Re: Wanted XM rear rotors
Posted: Tue Dec 26, 2023 10:03 am
by Dieselman
XMdownunder wrote: ↑Tue Dec 26, 2023 2:09 am
Thanks dieselman I got some brake parts in my stocking no better way to spend boxing day in the shed under the back end of an XM. Its too flaming hot to go to the beach anyway.
We have the same problem...well, not quite...
Crikey, you did well to obtain disks and pads on 24th December, the Uk was unofficially closed for business after 21st December.
Major tyre distributors gave up from 15th December to 8th Jan 2024. Not too much of a problem on an Xm because, they have a spare.
Re: Wanted XM rear rotors
Posted: Fri Jan 05, 2024 1:30 am
by XMdownunder
My new rear rotors and pads have been delivered and I am preparing to fit the parts. My Haynes manual 3451 advise when replacing rear disc first depressurise the hydraulic system but reading further on Haynes does not advise to depressurise when replacing the front discs. Is there a reason to depressurize to remove the rear discs and not depressurise to remove the front discs?
Re: Wanted XM rear rotors
Posted: Fri Jan 05, 2024 7:41 am
by Dieselman
Ignore advice to depressurise when fitting brake parts.
As long as the brake pedal isn't depressed the brakes have no pressure in them and have an open return to the reservoir.
Having both rear wheels off is an opportunity to bleed the rear brakes.
If both wheels are hanging you need to set the height control to maximum height to create pressure in the rear suspension circuit.
If either wheel ram is supporting the weight of the rear of the car, the suspension circuit has pressure, so you can bleed the brakes at normal ride height.
Re: Wanted XM rear rotors
Posted: Fri Jan 05, 2024 1:57 pm
by citroenxm
Although a 1998 car will have anti sink. Which will retain suspension pressure when the engine is off...
Follow dieselmans advice.. you will need to remove the rear caliper off the arm to get the disc off... remove the caliper COMPLETE with the pad retaining bolt in place. This will hold the two caliper halfs together.. you can maneuver the caliper with the brake pipe attached after removing the rear heat shield but do it with care. Check it over for any rust blisters although I'd not thought you would have any down your way....
Swap the disc. Refit the caliper. Then work on swapping the.pads pay attention to the position of the anti rattle spring U and how the bolt sits in relation to it across the.middle.
Re: Wanted XM rear rotors
Posted: Fri Jan 05, 2024 9:59 pm
by XMdownunder
Great thanks gents I will proceed according your advice. It must be frustrating having to deal with penetrating rust in these underbody components I will have to recoat the brake shields, see jpg file attached this post (hopefully).
Re: Wanted XM rear rotors
Posted: Tue Jan 16, 2024 9:37 am
by XMdownunder
Hello gents just a short report that my new 224mm rear brakes installed no problem the new brake pads sweep right to the outside edge of the rotor. I tested them under hard braking just short of ABS and am happy with result. While I am on line I need to confess my mistake in quoting wrong ORGA for my car, my car is ORGA CJ 8019 my apologies.
I had a beaut new issue pop up today during short drive the hydraulic pressure, stop command, coolant level and engine oil pressure warnings lit up together. It was a hot day of about 30 degrees C and I pulled over check fluid levels all OK gave 10 minutes cool down and when restarted the lamps stayed off. But the same lamps came on again at end of the short trip home. I rebuilt the hydraulic regulator about 4 years ago it is now cycling at about 12 seconds. I was planning to replace all spheres next job (my suspension is always hard) and have contact with fournitures auto in France who can supply full set of 9 IFHS spheres to suit my XM hydractive 2. Could anyone attempt to diagnose that combination of warning lamps please?