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Discussion Starter #1
howdy fellas.
i have taken off my front wheel from my africa twin to get it balanced and new discs on the front but really hard to get callipers back on.
i will change brake pads aswell but never did it before so any advice would be appreciated.
is there anything other than wd40 to help widen callipers so i can get them sit onto the disc and do i have to loosen the cap on the brake fluid to release pressure?
many thanks.
dj
 

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Use a clamp or a big screwdriver to lever between the (old) pads. Make sure the exposed part of the brake piston isn't corroded before forcing it back. Just loosen the reservoir cap slightly and cover with a rag to catch any fluid expelled. Careful with the reservoir screws as they can round easily - best use JIS screwdrivers. And a good time to change fluid while your giving the braking system an overhaul.
 

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I just did front and rear brake caliper service. Took the calipers of, took the pistons out, changed piston rubber seals, cleaned the pistons, cleaned the caliper, changed bleed nipple (you wouldn't believe how corroded it was) and few other minor things. Of course changed the brake pads and fluid (you need to do that after disassembling the caliper).
After cleaning and servicing the caliper, the pistons went in really easily and changing the brake pads, putting it back on the bike and changing the fluid was a piece of cake.. The difference in braking power compared to only changing pads is noticeble (for example i realized that in my front left caliper only one piston was moving properly, the second was somehow stuck probably due to failed rubber seal and a lot of dirt).
I highly recommend doing the whole service, it doesnt take more than 40 minutes per caliper and you dont really need any special skills.
Here's a nice vid explaining the service in a simple way: https://www.youtube.com/watch?v=SDA5zVyrNf8
There's a ton of videos showing the change of fluid using just a jar of old fluid and some transparent tube. You can also use a simple syringe. works perfectly to suck the air out.
Be very careful with the fluid though its quite agressive to the plastic.
Oh and here's a kit for the service from ebay: Honda XRV 750 Africa Twin 93-04 front brake caliper seal kit 1993 1994 1995 1996 | eBay
 

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howdy fellas.
is there anything other than wd40 to help widen callipers so i can get them sit onto the disc and do i have to loosen the cap on the brake fluid to release pressure?
I don't think WD40 is a good idea as it attacks the seals. Also, I'd crack the bleed valve in the first instance, not the reservoir. I would suggest the following:

- You need to work on one caliper at a time. As you have the wheel off, make sure you have block of wood or something between the other caliper's pads.
- For the caliper you're working on, carefully push the pistons further out (as far as you can without risking them popping out completely).
- You will need to do the previous step one piston at a time while clamping the other one with a g-clamp. (Often one piston will be more stuck than the other so will want to come out first.)
- Clean the exposed pistons with rag/brake cleaner/whatever. This is tricky in situ if they are pitted or badly corroded, but do your best.
- Open the bleed valve on the caliper slightly then use a g-clamp around the piston/caliper to gradually push the piston back in. (Again, with the other piston clamped.) If your pistons are really corroded, at worst you will mangle the seals.
- Close the caliper bleed valve. Clean up the mess :)

If your pistons were okay this will probably be fine. You will in any case get the calipers back onto the discs. When you reinstall the wheel and pump the pistons out again until the pads contact the discs you may find the reservoir level has gone down as you likely lost some fluid. Top up if necessary.

It is definitely worth dismantling the calipers completely from time to time and replacing the seals. It isn't hard, it is just messy and takes a bit of fiddling. If you're going to do this, just remember to ease both pistons almost fully out before disconnecting anything, otherwise you will kick yourself!
 

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it doesnt take more than 40 minutes per caliper and you dont really need any special skills
No special skills but I think your timing is wildly optimistic for a novice! I'd budget at least a day to do a proper job on all three calipers.
 

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I may be optimistic, but i think you're a bit pesimistic :)
Seriously though it did take me a bit more time for the rear brake caliper which i did first. But once i figured out the system it took me less than two hours to complete both front calipers and reasemble everything on the bike again (I actually remember the time cause i had to pick my GF for lunch). And the level of my mechanical skills is really basic :)

but hey, everybody's got their own pace i guess
 

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Discussion Starter #7
Well thanks alot guys,
That video was great too AL3s.
im not very good at mechanics but what would you recommend for cleaning the pistons?
petrol? soft emery cloth?
This is a great forum and thanks to the lads for passing on their knowledge about such a great bike.
dj
 

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I followed the advice in the video and cleaned the pistons with brake fluid and a cloth. If it's agressive enough to damage plastic, for sure it will be more than enough for dirt and crud:) I tried not to allow any other fluid or dirt get on the pistons and into the piston holes other than brake fluid (while i was cleaning the caliper itself (for that you can use white spirit or contact cleaner spray and toothbrush) i kept a piece of dry cloth (an old sock) in the piston hole).
The author of the video i posted has some other nicely explained videos regarding cleaning and servicing calipers, check them and you should be on the safe side.
The only tricks here are as Mark mentioned to do one caliper at a time and don't allow the brake fluid to poor out complely once you remove the caliper from the banjo bolt and hose. I use a pair of locking pliers to squeze the brake hose near the caliper. After i reinstall the caliper I top up the brake fluid and push the air out (check some brake bleeding/fluid changing videos, like this one: https://www.youtube.com/watch?v=P7jVI28x82U).
 
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