Adding extra brake vacuum capacity for increased braking

[robdav]

I have a 130 with just adequate brakes at sea level.

We are heading to Sth America next year and will be driving at 4000m plus according to those who know more about the place than I currently do.

Reading Kym Bolton's "Goanna Tracks" - Kym is currently in Sth America - he has had an extra vacuum tank and pump fitted to his Canter to increase braking efficiency at altitude.

What do you think! Can I do something similar on my 130?

[dero]

I find the brakes on my 97 130 very good . I have replaced the vac pump & booster , standard stuff , Do you know the condition of yours ? If all is in good nick I am surprised you are not happy with them .

[Judo]

I'm not sure that a vacuum tank will help. You need a better booster.

If I picture a 1L tank at 50psi or a 100L tank at 50psi - the volume of the tank is not giving any difference in pressure.

[JDNSW]

The brakes on the Defender are usually considered adequate. In what way do you feel they are inadequate? Pedal pressure too high? Poor braking performance? Brake fade?

None of these will be affected by an increased vacuum storage. The only thing that will be improved by extra vacuum storage is the ability to make multiple brake applications with the engine idling or off, and this may indeed be an advantage in mountain driving.

However, what may be worth considering is changing to a booster with a larger diaphragm area (such as a dual diaphragm one), as the assist force depends on the atmospheric pressure x diaphragm area, and at 4000m the atmospheric pressure, and hence braking assistance will be only be about 60% what it is at sea level.

Either or both can be fitted, but you would need to talk to a brake expert, who should be able to advise what is available that could be fitted.

John

[robdav]

Thanks for the feedback.
My 1996 130 has a camper on the back with an all up weight of 3000kg. Breaking is adequate under normal circumstances but the pedal goes to the floor in an emergency, soil your pants, situation. No way does it go near to a lock up. Not that that is a desired outcome. But the pedal hitting the deck is a worry. I've had this truck for 18 years and I never remember the brakes being real flash!
I have done all the usual. Bleed the system, new pads, new rotors not long ago.
Since my post I have read that the servo assist can develop hairline cracks but I have yet to investigate this further.
I had a soil your pants moment coming down from Thredbo a few years back, total loss of brakes, so the Andes will demand that I improve current performance. Other wise there could well be another cross on the Death Road in Bolivia.

[dero]

There is a 12v vac pump option , don't know if it would suit , try summit racing ? for details . they are available locally at speed shops etc .

[roverrescue]

My 1996 130 + Bleed the system, new pads, new rotors not long ago = bad brakes
your answer is:
servo assist can develop hairline cracks

Get someone to jump the pedal while you watch the booster closely. At the ridge where the master is bolted you most likely will see a crack leaking all your hard hearned vacuum to atmo.

The problem is a brand new booster will likely crack before you even get to the death road!
It seems that the manufacturers have forgotten how to make a long lasting booster,
I would look to retrofit or go the tightarse but effective option like me.

I took two hairline cracked boosters. I carefully turned the face and rolled edge out of one and then aligned it to the second booster. Glued the two pieces together with high grade Sikka.
So now there is no flex at the face. And no leaking vacuum equals good brakes.

And btw - a Canter needs more than just a booster upgrade to provide stopping power. Those things bring the suck when you want to stop!

Steve

[jabber]

Beautiful truck! I'd say do a full brake service; then see if you need additional braking.

I find the standard brakes at altitude, here in Colorado, are fine.

[Ancient Mariner]

Loss of vacuum should only mean a hard pedal something else is wrong if the pedal hits the floor:o I would fit stainless braided hoses reco the MC and callipers and altho the poor cousin of engine braking consider fitting an exhaust brake

[Brid]

Agree that it doesn't sound right & best to sort that out first. If you are contemplating some sort of upgrade to handle a lot more brake pedal work, it might be worth considering exhaust brakes.

[robdav]

Thanks Jabber. You come from a lovely part of the world. In 2010 we dropped in to get our truck checked over by Rob and Ted at MIT in Evergreen. A Rangie owner stopped to chat at Buffalo Bill Dam I think it was, and gave us Rob,s details.
Great service and very friendly.
Given that your just down the road you may know him. Say hello from Rob and Gael if you bump into him.

[robdav]

Thanks Steve. I will start at replacing the master cyl and work my way through the system. Any idea what might fit if I go down the retrofit path?

[robdav]

My 1996 130 + Bleed the system, new pads, new rotors not long ago = bad brakes
your answer is:
servo assist can develop hairline cracks

Get someone to jump the pedal while you watch the booster closely. At the ridge where the master is bolted you most likely will see a crack leaking all your hard hearned vacuum to atmo.

The problem is a brand new booster will likely crack before you even get to the death road!
It seems that the manufacturers have forgotten how to make a long lasting booster,
I would look to retrofit or go the tightarse but effective option like me.

I took two hairline cracked boosters. I carefully turned the face and rolled edge out of one and then aligned it to the second booster. Glued the two pieces together with high grade Sikka.
So now there is no flex at the face. And no leaking vacuum equals good brakes.

And btw - a Canter needs more than just a booster upgrade to provide stopping power. Those things bring the suck when you want to stop!

Steve
I think I have a hairline crack in the servo unit. Was wondering if to strengthen a new servo unit it would be appropriate to cut a strengthening patch/piece out of the old servo and then Sikaflex as suggested. Not as good as rolling out as the edge but easier for me to manage and still provide some stiffness to the stress area.

[Bush65]

I'm not sure what calipers are on your 130. I assume the front brakes have the calipers with 4 large pistons and vented rotors. I also assume the rear brakes have the same old 2 piston calipers as used with the smaller wheel base Land Rovers.

Under hard braking with an empty short wheelbase vehicle the stock rear brakes were chosen so the don't lock the rear wheels. As such they don't contribute much to overall braking.

The rear brakes could contribute much more to overall braking when there is more traction on the rear tyres, i.e. when heavily loaded and long wheel base.

If I had a 130 with its long wheel base and that weight permanently on the back, I would change the rear calipers to the ones with 4 small pistons as used on the front of a Defender 90. AFAIK Disco I and RRC fron't calipers used the same 4 small pistons.

[clubagreenie]

Increasing the volume won't increase performance but it will give you a better margin of reserve if there's a failure of vacuum supply and you need to use the brakes with the engine off.

I would look at the elec pump options if you're that worried but a good service of the system will probably go a long way to improving the situation. The elec unit will need a reservoir anyway.

[BilboBoggles]

Just wanted to post my experiences.

I have a 2003 TD5 and a new PUMA. Since I bought the PUMA I realised the brakes on the old TD5 were crap. This was drilled home when I towed a small 2 ton trailer down some steep roads nearby. The pedal was soft and squishy on the first pump, and even on the second pump it was plain scary. The pads were not too worn looking to have around 2-3 mm left on them. The rotors were fairly worn - with 140,000ks on them since they were last replaced.

I recently had it serviced with new pads/rotors all round, new fluid, and the wheel bearings sorted out. The pads were genuine and not that cheap. BUT I now have brakes on the TD5 that are actually slightly better than the new PUMA.