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I Found Another Problem Job!

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tony barnhill

tony barnhill

Great Pumpkin - R.I.P
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MGB calipers are easy to rebuild; heck, they're a snap....Midget calipers are almost impossible to rebuild!!

I've ruined 2 rebuild kits trying to rebuild 1 caliper...here's what the instructions say:

"1. Coat a new fluid seal with Disc Brake Lubricant, (the seal must be dry on application). Ease the seal into the groove in the caliper bore and gently work round it, with the fingers, to bed it correctly. It will be noted that the fluid seal groove and the seal are not the same shape in section, thus when bedded in, the seal feels proud to the touch at the edge furthest away from the mouth of the bore."

"2. After lightly coating the piston with Disc Bake Lubricant, insert squarely into the caliper bore. With fingers only, press in piston until approximately 5/16" is left protruding."

"3. Coat a new wiper seal identified by its "V" groove with Disc Brake Lubricant, (ensuring seal is dry) and fit it into the new metal seal retainer. Slide assembly squarely, seal innermost over the protruding portion of the fitted piston and up to the bore mouth."

"4. Remove piston clamp from mounting-half of caliper and, with aid of distance piece, use clamp to press home the seal retainer and seal. Using the clamp only, press piston fully into caliper bore."

No problem with #1, #2, & #3.....#4 is where the problem lies (& where the metal seal retainer gets bent every time!)

The new metal seal retainer <u>WILL NOT</u> go in its groove in the caliper bore with the new wiper seal in it like its supposed to.....however, the old metal seal retainer WILL go in with the new wiper seal in it!

Trouble is, because the rebuild kits had new metal seal retainers, I didn't worry about saving the old ones!

Time to call PeterC!!

This <span style='font-size: 12pt'>SUX!!</span> I've never had a problem rebuilding MGB calipers in all the years I've messed with them; heck, a few weeks ago I rebuilt a pair for my '74-1/2 MGB GT in about an hour!

DARN this Midget!
 
Ha, Peter C has non Moss parts that just might fit. Whoops, did I say that.
 
Jack - I only use Moss parts on MGB calipers & never have a problem!

Peter told me you have to sand some of the outside diameter off the metal seal retainer & fit it back in a particular way - that round is not round!
 
Tony
You are doing it with the caliper halves seperated?
It's been awhile but I think I used a small block of wood or something to cover the entire retainer and gently tapped all round it until it goes in. not easy and I have bent a couple too.
Mike
 
mk2sprite said:
Tony
You are doing it with the caliper halves seperated?
It's been awhile but I think I used a small block of wood or something to cover the entire retainer and gently tapped all round it until it goes in. not easy and I have bent a couple too.
Mike
Click to expand...
No, halves are not separated (but, then, I never separate MGB calipers either)...MGB bearing race works great for a 'distance piece' like your block of wood....I just can't understand how the old one just slipped right back in place but none of the new ones would even think about going in!
 
If I remember correctly, and possibly not with this cold, I put the metal retainer in before the piston.... Hmmmm.
 
I just followed the instructions.
 
Tony, I take the new retainers and chamfer the lower edge slightly before attempting to put them in the bores. As they flex from uneven pressure they bow making them nearly impossible to get in. By only removing about 1/64th on the chamfer it allows them to snap in place.

I use the smooth wheel on my bench grinder to do this.

Ben
 
That's my problem:
I usually try it the way I seems it should work and when all else fails, seek the instructions. /bcforum/images/%%GRAEMLIN_URL%%/smile.gif
 
Me, I took the easy road gave PeterC a call. Sent my old calipers in with a reasonable fee, and got nice rebuilt ones back, ready to go.

I give full thumbs up to folks who can do this themselves, that's for sure. I understand my limitations, and proceed accordingly. /bcforum/images/%%GRAEMLIN_URL%%/smile.gif
 
this is soooo much easier with the calipers split - just two more gaskets (not included in kit). I put the retaining ring in before the pistons went in. Just gently tapped with wood covering
 
I split mine as well, however, the manuals all say NOT to split if possible. Big warnings there.
 
I've split my calipers to rebuild them also. Re-assembly is easy, so I don't know why the 'do not split' warnings abound.

I've found that the metal retaining ring has a small burr around the outer edge from the die cutting and stamping process. you can feel it with your fingers if you can't see it. Similar to what Ben does, I used a light touch on disc sander to remove the burr and make a very slight chamfer on the outer edge of the seal retaining ring. They then installed easily with gentle taps of a small hammer. There's still plenty of interference to provide a secure installation, too.
 
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