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[countrywoman]

So got some pads and a fitting kit for the Austin , now the Omega doner was ex plod but there is only one set of rear pads listed in Apex book. They are quite loose side to side and pins and anti rattle are to narrow . Any chance it has vented rear callipers fitted as they are solid discs , ATE callipers on rear with 40 cast in.

[Doctor Gollum]

That caliper must ONLY be fitted with a 20mm VENTED disc.

All Omegas use the same rear pad

40 refers to the piston diameter.

Incidentally, this caliper is unique to the Omega and requires a different fitting kit, the parts of which were only available from VX.

The differences are given in a post in one of the help sections. This is something not to be skimped or ignored as it Will result in total brake failure as the pad wear.

Basically the pistons extend enough to haemorrhage fluid.

There is also a chance that the non vented anti rattle clips can effectively lock the brakes off by jamming between the pads.

[countrywoman]

Thats what I thought , cheers .

[Doctor Gollum]

You cannot buy after market vented calipers for the Omega.

Your options now are:

1. fit non vented calipers, which are available, use solid rear discs and the freely available non vented fitting kit.

2. Used vented discs with the correct fittings.

3. Use a completely different caliper/disc/pad from say a five stud Cav C or Vectra B.

[countrywoman]

Vented disc me thinks, have access to an Apex book so will check dimensions to make sure it will fit calliper.

[Doctor Gollum]

Vented disc me thinks, have access to an Apex book so will check dimensions to make sure it will fit calliper.

286mm X 20 from memory.

Apec list, or certainly used to, a vented fitting kit. They lie, it isn't suitable for the Omega disc... The pins are too short and the spring clips are too narrow.

All Omegas use the same diameter rear discs.

Here's the post I meant.

https://www.omegaowners.com/forum/index.php?topic=127928.0#new

.

[Nick W]

There are various DIY solutions to the vented disc parts not being available. On an Omega they're probably worth doing.


On your Austin, the easiest way of dealing with the problem is to source and fit calipers suitable for the solid discs as it doesn't need the questionable improvement the vented ones provide. That's especially true if it already has solid discs

[countrywoman]

Cheapest will be to fit new discs , they are a bit ratty anyway . Have one correct size pin in my box of old brake bits !

[Doctor Gollum]

The 2.6 /3.2 were vented because the TC works differently to the 2.5/3.0 equipped cars.

Late European cars had the option of ESP, but we had to make do with TC which hammers the rear pads during wheelslip.

To be sure that your current calipers are correct, they should have an 8mm insert between the two outer halves, might now resemble a rusty stripe.

The 40 suggests that they are for vented discs, but I have never worked on a prefaclift Plod car, so it could have had a hybrid caliper fitted ie non vented with the larger piston bore.

Basically, if that stripe is present, measure it carefully and add the figure to the 12mm disc. This will give you the correct disc thickness.

Again, fitting a vented caliper to a solid disc could well kill someone.

[countrywoman]

Had a very careful look and measure , it is a solid disc set up as not much space for disc to run through calliper. Its just the fitting kit is rubbish, pins and spring short and the end that goes in the outside is way to small for the hole . Maybe its because it has the larger callipers , wonder if they are used on anything else?

[Doctor Gollum]

Physically the caliper halves are the same size, the difference is the 8mm spacer and/or piston diameter.

As far as fitting goes, they are interchangeable with the appropriate disc.

Mintex also do a fitting kit, p/n in the link a couple of posts up

[countrywoman]

Yes £7 and a bit on the bay, worth a try .

[Enceladus]

Surely the vented caliper pistons are slightly larger than the pistons for non vented solid discs?

The rear calipers for 12mm thick solid discs have '40' cast into the piston housings.
Calipers for 20mm thick vented rear discs have '42' cast into the piston housings. So roughly 9% more surface area on the pistons.

These vented calipers also have the 8mm thick spacer between the two halves to allow for the extra 8mm thickness of the vented disc.

countrywoman says her calipers have 40 cast into the housings. 40 would indicate solid discs and standard fitting kit. Check and see if there is an an 8mm spacer sandwiched between the castings? No spacer would confirm solid discs.

What's the part number of the fitting kit you have? Assuming you have solid disc calipers it sounds to me that you have a Vectra B fitting kit which won't work.

[Doctor Gollum]

I had forgotten that the 3.2 caliper had "42" stamped in them. 

Everything else that Rae has mentioned stands, although I wonder if the calipers and discs that were fitted to this donor car were actually Omega ones to begin with

[countrywoman]

It is standard solid , just wrong / bad fitting kit that confused me plus the fact pads are a lot slimmer than the space they sit in . Think my brain was out of gear that day (old age/dyslexic !)