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The 11" x 3" wide front drums came out on the SIIA forward control in 1962, they were fitted to the S2A six cylinder in 1967 the booster pedal box came out on the six cylinder in 1969 IIRC and continued on all SIII six cylinder and by late SIII all had the booster pedal even if they were 88" or 109" (around 1980).
So there are plenty of donor models (including Army SIII) to donor the pedal box off.
My army SIII would be very upset if I swiped its pedal box, but I do have a couple of 6 cylinder S2a's that would complain less.... they might also be persuaded to offer up their back plates etc. to the cause!
More importantly the SIIa will have the correct size wheel studs, not that you'd be using old drums.
I'm watching this with interest... I got my 86" firewall reinforced (2mm sheet) and fitted the pedal boxes. I also got the 11x3 drums on the front before work dragged me away from home for the best part of 18 months...
Back at home now and itching to get the car rebuilt.
From memory the inner wing needs some butchering to accommodate the pedal boxes but I'm interested to hear what's the best solution with regards servo assisted brakes. Also, do the tears remain the standard 10"?? I'd hoped to leave the rear axle alone... At least for now until I get around to the Diffs:)
I've been distracted with another LR and some health issues, but whilst investigating the "vague" steering in my '56 I noticed that another of my 86" LR's has a later type steering box fitted. This in turn lead me to consider whether the better option is to address the pedal box and steering fixes/upgrades together, rather than potentially making two separate assaults on the firewall....Quote:
Originally Posted by Yorkshire_Jon
My (non LR) experience of braking systems is that because of weight transfer the rear brakes are far less important than the front under heavy braking. Having said that, how often will the front brakes of a LR cause the rear wheels to "un-weight"? Any time the rear wheels have weight on them they have traction and therefore can assist with braking. Too much braking for the available traction and the wheels will lock. In racing cars we used to use an adjusting valve that allowed us to increase/decrease the amount of rear braking to suit the conditions. In an old LR I don't think you'd want the rears locking up prematurely......
The rear brakes also serve the function of providing drag at the back to prevent the rear of the car acting as a large pendulum and overtaking the front (spinning) when braking through a corner. The tendency to spin with little warning usually worsens with decreasing wheelbase, so the 86" with improved front brakes might well behave this way. This happens when there is too little braking at the rear, but "too little braking" refers to the force applied to the ground, rather than the "brakes" themselves. So "too little braking" also happens when overly large brakes cause the rear wheels to lock, because a skidding wheel provides less deceleration than a braking+rolling one (static friction is greater than kinetic friction).
My thought would be to improve the rear brakes, but if you want to do that at a later time then at least make sure that what you have now are working 100% (Mintex shoes, skimmed/replaced drums etc.). If/when you do improve them, I'd stick with a combination that has been used (preferably in an 88") by LR themselves including the correct front/rear bias valves or dual circuit master cylinder etc., as this should result in a system with the correct front/rear balance. Failing that just make certain the rear brakes don't lock up early under any circumstances (damp road+heavy braking+cornering!).
That's my plan anyway!
I know stuff all about these old girls and driving them Warb, so treat this with that in mind:
I do wonder if you're over thinking this. I'd have thought that tyres were more important in controlling the vehicle than brakes, particularly considering the modest performance of these beasts. I'd also price/consider fitting a complete system from a later LR rather than mix and match on the grounds that some faceless engineer has earned himself a comfortable income doing the sums already.
Whatever, I completely agree with having the best components and having the whole system in the best condition you can get. Good brake drums and very good (and fresh) shoes will probably achieve more than anything else.
Fitting a system that was used by LR themselves is certainly the easiest way to get a good front/rear balance (I actually said it at the end of my last post!). However the 88" never had the 3" wide drums that Yorkshire_Jon has fitted, so that makes it harder!Quote:
Originally Posted by crackers
Tyres are indeed very important, but if the pedal effort required to get the front brakes to "work" causes either too much or significantly too little rear braking, then problems can arise. It is almost certainly the case that a good modern tyre will outperform the original brakes so you'll probably struggle to lock a wheel under braking. But if we start to improve the brakes, and make tyre's job harder by putting it on a wet road and adding some cornering forces, then who knows?
Unlike acceleration, the need for braking is ultimately "out of our control". By which I mean that I can drive carefully, accelerate gently, prepare in advance for every maneuver and be as aware as humanly possible of hazards, but still on occasion there will be a need to hit that brake pedal hard - and it is that "worst case scenario" that we should target.
I should note here that I live in an area where suicidal 'roos, wombats and deer are (from what I can see) employed by the local smash repair companies to bolster their businesses, so I am constantly faced with the reality that something might leap out from behind a tree at any second!