Restoring Some 105/115 Rear Calipers... - Page 2 - Alfa Romeo Bulletin Board & Forums

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post #16 of 41 (permalink) Old 08-12-2010, 06:44 PM
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Thanks Eric.

Pete

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post #17 of 41 (permalink) Old 08-31-2010, 04:34 AM
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2 things/questions please ...

1. I notice that the centre pin in the caliper halves were also plated. No issue doing this? I guess they must have been plated originally, but mine definitely do not look like they were.

2. The bolts that connect the calipers to their mounting plates, I assume they are black oxide finish also?

Thanks
Pete

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post #18 of 41 (permalink) Old 08-31-2010, 10:01 AM
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Hi Eric,

Great thread. Where do you get the seals used between the two caliper halves? You mentioned that they're not included in the re-build kits.

Best regards,
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post #19 of 41 (permalink) Old 10-25-2010, 11:34 AM Thread Starter
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Sorry for the delayed response guys... I guess I wasn't subscribed to this thread.

Pete, no issues with the plated pins.

Monsai - We include them with our seal kits but, for those adventerous types. Look for a buna seal that is 2.4 x 5.3 hope that helps.

E.

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post #20 of 41 (permalink) Old 11-22-2010, 02:15 AM
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DOT5 vs DOT4 and caliper rebuilding

Hi,
Without claiming real expertise on the topic, I wanted to raise the issue of lube used during caliper and master cylinder rebuild, compared to the type of brake fluid to be used later on.
Any of you who have considered using DOT5 (silicone) fluid and have done some research, have probably come across recommendations to completely rebuild the hydraulics before changing to DOT5.
While I have always stayed with DOT4, my brother (cotie1750) did build with DOT5. His brake master was rebuilt by a professional re-sleeving service (not Eric's outfit), but without any dialogue about what type of brake fluid was going to be used.
What then happened when we were putting things together is that the brake master's pistons got jammed and wouldn't return. A lot of work later and we found that there was a large amount of congealed semi-solid crud inside the cylinder - what we presume to be the rebuilding grease after exposure to DOT5 silicone fluid.
I know that the ATE rebuilding paste I have is specifically for DOT4, although I have no idea what range of rebuilding pastes are available nor what compatibility they claim to have.

But my main point here is for those of you who want to use DOT5 silicone fluid, beware this possible problem. I presume the best way to approach this is to build all cylinders simply using DOT5 fluid instead of any grease. If you're having cylinders rebuilt by a professional service, I would suggest you inform them clearly beforehand that you intend to use DOT5.

Again, just a "heads-up" warning.
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post #21 of 41 (permalink) Old 11-22-2010, 02:21 PM
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Does anybody actually bother with DOT5 (other than your brother). Seems like a waste of time to me ...

Do any new car manufacturers use it?
Pete

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post #22 of 41 (permalink) Old 11-23-2010, 12:55 AM
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Hi Pete,
Only based on stuff I've read a long time ago, I think it's used quite a bit in the classic car area (no, not so much Alfas, but other makes), and I think the US military was using it if I recall correctly. I agree, I doubt any new vehicles are being delivered with it.
Personally I don't have any interest in using it, but some people will, hence my warning here. Some people find the benefit of not absorbing moisture a big plus, if it can reduce their regular maintenance (brake flushing) needs. Personally I have no problem with doing maintenance so I prefer DOT4.
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post #23 of 41 (permalink) Old 11-23-2010, 07:48 AM Thread Starter
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I find what I call "Caliper Worms" when people have used 5. Most never really clear out their 3 or 4 and the mixture solidify's into a black paste in the passages. It usually gets pushed through and gathers in the bores. Yuck!

Eric Shea
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post #24 of 41 (permalink) Old 05-26-2011, 06:39 PM
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Mighty nice work, thanks Eric. I've just found it as I'm now rebuilding my own GTV rear calipers.
I've struck a question about re-fitting the piston into the caliper half - after making everything clean and shiny, I thought I'd just drop the piston into the bore to make sue everything was free and non-binding, before I fit the main piston seal and button everything up. However I find that the piston doesn't drop right down over the central post and fully down into the bore. I haven't tried to force it in very hard as I would not expect that to be needed without any seal in place yet. (Never have with all the Alfetta and Alfa Sud calipers I've done, or with the GTV's front ones.) Got any comments on this for us please, Eric or anyone? Should it just drop right in?
Thanks all,
Graham in NZ (1750 GTV)
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post #25 of 41 (permalink) Old 05-26-2011, 07:30 PM Thread Starter
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Knockback Mechanism

That's perfectly normal. You're working against the spring loaded knockback mechanism at this point.

Make sure the mechanism inside the piston is clean and operating freely. In most cases they are held in with a c-clip. Best to pull them out and clean them with compressed air and brake cleaner. Reinstall them and shoot them with WD-40 to wick any further moisture out.

For the pin, I like to use a Dremel with a small wire brush to make sure that is clean.

In this case a certain amount of resistance is good.

After you install the seals and push the pistons in, look for the bounce (the piston literally "knocking back"). This will tell you the mechanism is operating properly. This is fairly easy to do with an arbor press, not so much with a vise or hydraulic press. The piston should bounce back up about 1/8" from the bottom.

Good luck with your build.

Eric
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post #26 of 41 (permalink) Old 05-26-2011, 09:19 PM
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Eric, you're a champion, thanks mate! Your info and PDF explain everything. I've just experimented with a clean dry seal-less caliper, and yes the piston does push over the pin with just a little extra force. And once on, it does spin freely and does spring down and up against the spring. Beauty!
But man what a funky system for a disc brake. Almost as funky as the weird ATE caliper adjusting system used on Alfetta front and Alfa Sud rear. A common trick over here in the Alfasud world is to remove all that adjuster nonsense from inside the piston and then the brake works like a conventional disc brake, self-adjusting and self-clearanciing with the seal alone. Very nice. (You do have to sort an alternative handbrake system tho'.)
Thanks again!
Graham in NZ (GTV and Alfasud and 156)
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post #27 of 41 (permalink) Old 05-27-2011, 02:39 AM
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Sorry, I meant weird system on Alfetta rear and Alfasud front!
Regards all,
Graham H
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post #28 of 41 (permalink) Old 06-03-2011, 06:56 PM
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This is great! Can't wit to see pictures of the GTV6 rear calipers.

......... Bud Feigel ........<Oo \*/ oO>....... Lexington, Kentucky ........
'82 RED GTV6 / 2.5 - '86 WHITE Spider Veloce 2000 - '71 GREEN GTV 1750
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post #29 of 41 (permalink) Old 06-04-2011, 07:04 AM Thread Starter
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Search is your friend.

http://www.alfabb.com/bb/forums/susp...r-caliper.html

Eric Shea
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post #30 of 41 (permalink) Old 06-29-2011, 12:15 AM
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Hi guys,

I might be stupid here but I'm looking through this assembly procedure and something doesn't look quite right. The picture from the tutorial seems to show the opposite piston rotation from the IAP guide. Am I missing something - if not which is correct?? Doesn't one of these need to be rotated?

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