TS888

TS888

New Member
Not sure why I can't just leave well enough alone, but... I've been pondering the options for removing the vacuum assist from my 300Tdi Defender. The first option would be manual (non-assisted) brakes. That would eliminated the need for vacuum, and thus the vacuum pump.

The other alternative would be hydraulic assist ala' RRC or Disco, sans the ABS.

Pure manual brakes are attractive for simplicity, but it would require a different master cylinder (or training myself to use both feet on the brake). Given the simple brake pedal setup on a Defender that's not a huge obstacle.

I had an RRC, and the hydro booster is damn good. The downside is I'd be replacing a relatively simple mechanical vacuum pump with a mildly complicated electric pump and pressure canister.

Thoughts? Anyone gone manual?
 
Why would anyone want to make their brakes worse? WTF is wrong with the braking system as it is?
 
You could look at removing the servo and using leverage to compensate. Upside is that brakes have little or no travel at the pedal and there is more feel to them.
 
A can safely say driving around for 500 miles with litgle or no vacuum asdist in my 300 tdi was quite an eye opening experience. I did not ha e to do any other leg exercises for a few weeks after and some white knuckle moments

I would not adise it .... But if you must try it by disclknecying the vacuum hose on a very quiet road first....
 
please dont tell me this is for a road car.

i can just imagin you explaning to a judge that you were trialing an experimental brake system, and you ment to stop befor you hit the bus stop. let alone what any insutrance company would have to say.

That said if your doing it for a off road racer or trialing, i would think if you fitted a disco/rrc abs unit you could then with the right electrics lock each wheel as and when need as well.
 
My intent is to eliminate the vacuum pump, eliminating a potential point of failure that affects the engine and the brakes.

Hughesy and Discoandy, this isn't experimental or dangerous. Most race cars use unassisted brakes, and have excellent braking power and control. I have been apprised that making changes to my brake system could set me afoul of my insurance company. Wow, and I thought the US was run by greedy lawyers and nanny bureaucrats - then I moved to the UK.

I want the brakes to be the same or better, not worse. If I take out the booster, I'd go to a smaller bore master cylinder to compensate for the loss of assist, and balance that with changing the lever relationship on the pedal to approximate the same braking effort required by the assisted brakes. More pedal travel is likely unavoidable.

The electric/hydraulic assist from an RRC can fail (although in my experience the system is quite robust), but if it does the accumulator gives you several full braking cycles before you lose assist, and the engine is unaffected.

I should probably save my original thinking for the Pirate4x4 forum...
 
TS888 said:
this isn't experimental or dangerous. Most race cars use unassisted brakes, and have excellent braking power and control.
Click to expand...

They also have 6 or 8 pot calipers and ceramic disks.
Do you intend to change that part as well?
 
the only items that goes wrong on a 300 braking system is normally the brake pump operated by the camshaft - relatively cheap to replace, my advice is do not go the route of abs system and leave non assist braking to the race/rally/off road scene
 
This is strange, it really is strange.

Just leave the system alone and have a spare vac pump if your worried, it can be changed in 15 mins at the side of the road.

The RR system has even MORE points of failue given the electrics involved, electric pump, valves in the ABS block.......
 
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The 300TDI Defender is about as good a utility 4wd as you will get,there is nothing wrong with the original setup - at all.Why try to complicate something that works so well out of the box ?
The point is the elctro/hyd system is a bloody sight more complex than the vac system,and its compnents are massively expensive to buy - P38 pump is £900 odd from LR. Then you have to make it all work.
Why not put mind time to something useful like making it water/draught proof ?
 
I really do NOT get this. It is beyond all grounds of reasonable logic and common sense to even contemplate removing the vacuum and servo unit. The brake system that is in place on your 300Tdi is a very simple and reliable setup, hence the reason why Land Rover used a similar setup on their previous vehicles for well over ten years. The vacuum units seldom fail and if they do, it's little more than three or four Allen head bolts and a cardboard gasket that you'll need to remove to fit a new one. You will also find that if the vacuum unit does fail, you are reverted by default to having a purely manual braking system which makes the system less effective under hard braking circumstances and the pedal becomes very hard under foot.

Surely if you think that the brake system is unreliable or destined to fail, there must be something else that's bugging you like the rubber belt that is keeping everything running on time???

I'm not trying to be horrible, I just don't get it :confused:
-Pos
 
Just thinking out loud, folks. I understand that others may not get it. I thought there might be some like-minded tinkerers on the forum, but I'm sensing a "don't mess with factory" vibe here.

The LR 4 pot calipers are more than up to the job of stopping the truck. A properly designed non-assisted braking system will work fine with 4 pot calipers. The multi-pot thing is a recent development, and a bit like the megapixel race in digital cameras -- more is not always better.

Sorry if I rocked the boat. I readily admit to being a "subvert the dominant paradigm" type. If a part from another car works as well and is cheaper or works better than the LR part, I'll use it. If I can fabricate something I like better than what is available in the aftermarket, I make it. I'm pretty sure there's more than one way to build a proper truck.

As you were...
 
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You'll find that we all like to tinker on here and most of us are that keen that we spend a lot of the time fixing things that aren't broken. Just take a look around the forum, you'll soon see that. On the other hand, removing sensical, proven and reliable parts of the brake system is a different matter. If you were talking about fitting air brakes or something similar, that would certainly get a lot more people thinking along the right lines. I'd love to hear a defender hissing every time it came to a stop or as it reached pressure on idle.

What other ideas do you have?
-Pos
 
TS888 said:
Just thinking out loud, folks. I understand that others may not get it. I thought there might be some like-minded tinkerers on the forum, but I'm sensing a "don't mess with factory" vibe here.

The LR 4 pot calipers are more than up to the job of stopping the truck. A properly designed non-assisted braking system will work fine with 4 pot calipers. The multi-pot thing is a recent development, and a bit like the megapixel race in digital cameras -- more is not always better.

Sorry if I rocked the boat. I readily admit to being a "subvert the dominant paradigm" type. If a part from another car works as well and is cheaper or works better than the LR part, I'll use it. If I can fabricate something I like better than what is available in the aftermarket, I make it. I'm pretty sure there's more than one way to build a proper truck. quote;


Think YOU are missing the point,there cant be many people on here with a bog standard truck,but some things just dont need fiddling with.
I put a Chev Rat 502Cu in v8 into a 110CSW for a customer - with 480hp on tap that one needed better brakes,but ONLY when it was over 100mph.:D
Click to expand...
 
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