Definitive RD07 caliper replacement list

[tedmagnum]

I thought that starting this thread would help AT owners with replacing their rotting Nissin calipers...

New Nissin Calipers will cost £250 + EACH from Honda and im guessing that doesnt include the seals and pistons...

From my experience and research , the L/H caliper can be replaced with a unit from a Transalp, CR 25, CR250 , CRF450 and possibly XR650 ???

As long as the bike is from the mid 90's to about 2003, Honda seemed to use the same Nissin caliper for most of their trail bikes. Its only the carrier (hanger) that is different.

I have swapped my left hand caliper from one off dirt bike but the right hand one is a big problem as trail bikes tend to have only a LH brake.

Please add your experiences and advice to this thread...

[futter]

The shape and size of the caliper bracket depends on the disc size (276mm for an AT)

CB500's had the same as an SLR and they (CB500s) had twin discs so you might have some luck there.

[tedmagnum]

From another post, it seems that the NVT650 calliper DOES NOT fit.

Tranalp 650 callipers are another source of replacement though.

[mal]

I think when I enquired about new calipers the parts guy said they came complete with everything including a new set of pads , that was a while ago and I can't remember the price quoted

[icenian]

AT ones are supplied as a complete sub assembly, pads and everything. Bolt to fork leg and attach brake line, job done Oh except the bit with the brake fluid

Part nos. 45250-MAY-006 (right) and 45150-MAY-006 (left)

If they weren't about 250 quid each, and lasted more than a couple of years, it'd be the way to go!

[icenian]

Tranalp 650 callipers are another source of replacement though.

These apparently fit but the pistons are 31 and 29 mm; Africa Twin are 27mm.

That sounds similar but the area is about 20-25%. I guess that theoretically means more stopping power?

But it means 20-25% more lever travel too! That worries me a bit...

[fw750x]

Hi Icenian I have fitted T.A. 650 V3 2003 Calipers to my @ i have not noticed any difference in the lever travel But i have noticed greater stopping power .If you can get a set you will be doing yourself a big favour.Francis

[tedmagnum]

These apparently fit but the pistons are 31 and 29 mm; Africa Twin are 27mm.

That sounds similar but the area is about 20-25%. I guess that theoretically means more stopping power?

But it means 20-25% more lever travel too! That worries me a bit...

Its all about oil displacement.... As fw750x says, theres no difference...

If your really worried, you can just get the master cyclinder off a Transalp to go with them

[icenian]

Its all about oil displacement.... As fw750x says, theres no difference...

Ah, but oil displacement will be cross sectional area of the pistons times the distance travelled. Bigger piston = more oil. More oil = more master piston travel = more lever travel.

Of course that's just in theory and it doesn't mean in the real world it makes that much difference. Some of the lever travel will be just to close that wee hole between master cylinder and reservoir, so pressurize the brake line. Some will be to displace enough oil to make up for expansion of brake lines; and some for flexing of brackets etc. too, I guess? These effects will be the same regardless of what size pistons you have in the calipers.

So some proportion of the lever travel will be becaiuse of things that don't change; and some will be dependent on piston sizes. But in what ratio?

fw750x would have us believe it's a ratio of lots:buggerall That'll do me; if he'd left as fw750x-shaped hole in the hedge at the first corner he came to, he wouldn't be around to tell me it's OK.

If your really worried, you can just get the master cyclinder off a Transalp to go with them

a good backup plan

[BobA]

Just an observation here...


Remember, irrespective of the make (Nissin, Brembo, or No Name!!) the calipers on AT's, TA's, and Dommie's etc, seem to come in two distinct flavours.

I've owned two RD03's and two RD04's, and I've found the following

RD03 (single disk obviously) uses a single caliper, with two 30mm pistons

RD04 (and RD07 I'm guessing) uses TWO calipers, with two 27mm pistons in each.


Obviously, if you intend to change just the left hand side caliper, make sure the piston sizes are the same as the right caliper. There is a 27 or a 30 with an arrow CLEARLY cast into the caliper body.



Bob