Rear brake seal problem Defender 90 300TDI

Help!
I bought new pistons and seals for my 95 Defender 300 TDI.
They eventually arrived from Paddock. The problem is that I am having difficulty getting the metal outer seal retainer into the cylinder. It seems to be too big. I have damaged two already. I have two more but I'm hoping for some advice before risking them.

Thanks in advance for suggestions.

hi just received my front caliper overhaul kit from lr series (genuine lrover parts) and the instructions state the use of a special clamp ,looks bit like a g cramp with extra bits on it, just found said tool on dingocroft site a £165 ffs so going to make my own at weekend..

Would a piston ring clamp work?

PISTON RING CLAMP INSERTING TOOL CHAINSAW LAWNMOWER on eBay (end time 31-May-10 16:07:02 BST)

Thanks to both for your replies.
I think that the problem may be that the components are just poor quality. I measure the cylinder bore at the outer end as 47.6 mm and one retaining ring is 48.2mm and the other is 48.5 mm. The latter one is not fully formed, the outside wall is very dish shaped, the other one is less so.
Admittedly my bore measurement may not be exact as I cannot get the vernier calipers in properly. However, I don't think I am far off.

Baggyjim, I'd be interested to know what your retaining ring O.D.s are, if you are able measure them accurately.

I tap them in very gently using a pin hammer and a wooden drift (an old wooden ruler), working around and around the ring so that they go in straight.
Works for me!

I hate fitting these , you can use a very shot bit of pipe the same size with some flat bar on top the and use a small G clamp press them in , but they are pigs to get in right without splitting the caliper ....

well i battled with the first ones which were ****part:doh: ordered some from lrs and theyre gen land rover what a differance ,my ones are early 90 front so are 42mm dia, so had a hunt round and found a waste pipe fitting which was nice fit over piston and just bout same od as retaining ring, cut off 10mm piece used with flat plate on top and small g cramp (not a lot of room between ) and they popped in easy