Thread: Brakes - dimensions, ideal MC size for Defender calipers.

Hydroboost with 1.062" wilwood MC 35" tyres and 3500 kg works well for me .1" is std 110


AM

Hi Gav,

AM's post is the backstop.

If you've already got the Def front callipers (46mm pistons) do a search on all Dougal's old threads on this.

AM's solution is probably the 'direction' you should go. I'll buy your Def callipers .

Remember also that proportioning valves can be bought that are fully adjustable, maybe even in cab.

Don't let that limit what you're trying to do in stage one.

cheers, DL

Thanks - Discs are basically modified D3 vented rears I think, but need to confirm this. Yep, the D1 booster made a massive difference all on its own - that’s been in for a few years now and works great.

Yes, can get the in cab adjustable proportioning valve with the MC - been thinking about this but have to check with my Engineer to check legality. Almost any rear brake bias on an empty 101 will cause the back end to try an overtake the front so having this as a manual adjustment may be a no no.

Have looked through some of Dougals threads but can’t find anything relating to brakes though - do you know what thread it was in at all?

Ok, I’ve got myself a bit confused now. Found a 101 master cylinder in my parts collection today (brand new) and checked the bore size on it - it is 7/8”. If the standard 110 MC bore size is 1” then if I went to 1” I’d have a harder pedal but less travel. Ideally I’d like a safer pedal but obviously need to be careful about max travel on the MC.

Any thoughts as to which is more suitable for disc brakes - 7/8” or 1”?

I was thinking that the MC for drums would have a larger bore size than discs, not the other way around, but is my thinking backwards here?

FYI I’m running a D1 dual diaphragm booster.

TIA.

Interestingly, but probably not much help. Im deleting the vac booster on my E-Landy as most of my braking is by regen & the Electric vacuum pump chatter is annoying. It otherwise has a standard Series3 SWB dual circuit 1-1/8 master cylinder . (I'm moving the pushrod pivot closer to the pedal arm fulcrum to get a better mechanical advantage to compensate for loss of vacuum boost & thus mounting MC 20mm higher)


Disc brakes typically have a smaller master cylinder .

My Iveco 4x4 had a 1-1/8" Bosch MC with a 12" dual diaphragm booster standard but crap brakes, could do with a 1" or 7/8 now that I've fitted rear discs. I'm sure the 1-1/8 is to account for how much the the rear shoes wear and go out of adjustment. (so you don't run out of pedal).

Well found something interesting today when I pulled off the old MC - it has a 1' bore, but this new one that I can't recall where it came from - may have come with the vehicle, I have a tonne of spares for it - has a 7/8" bore - apart from that they are identical. Pick is a bit misleading - they are both the same length - to the mm.

IMG_0532 by Gavin Gregory, on Flickr

Will go with the 7/8' one I think - because it's new and I think it will work with the discs - should also give me a bit more assistance and I've never been short on pedal travel. Pedal ratio is 4.9 to 1, but had a close look and I could indeed change this without too many dramas to give myself a little bit more, but will leave this unless I think the end result isn't quite what I'm after. With the dual diaphragm booster I've never had any issues with how it stops - I could lock up the 36" tyres if needed, so thinking I'm not going to have any issues, just the benefits of having brakes that will always pull up straight and not require as much maintenance. To be honest, the drums have been great since I rebuilt them a couple of years back but I'm still happy to be leaving them behind. Have all the dimensions from everything now, so will sit down and run some calculations - which the Engineer wants to see anyway.

Home star
I’m all but certain that “stock” defender is 7/8” bore
Same as most hydraulic over ride trailer brakes

S