Agree with all your questions and assumptions @NoGaBiker . One thing to add to that is that every person who is smarter than me (hey wait, that's about everyone so let me get specific) who has an engineering/automotive/experienced background (that feels better) has always told me that the front brakes are much more important than the rear brakes. Or at least that they support a tremendously larger amount of the braking function. That's why the front brakes almost universally wear out faster than the rear.

It could be that Marketing finally won out over accounting and spec'd them all the same so that "Bigger" sounds better to those who aren't really going to push the off-road performance. But I agree, would love to hear the answers to your Q's.

One other point that came to mind. I suspect that the Lucky8 version (if custom) and the JLR parts for an 18" (parts above) would both have the same design challenges. Do you suspect that if Lucky8's are custom that they have some engineering wizardry that makes them perform better? I think I read on their page that they use the same brake pads so the surface area of the braking grip should be the same. Here's a question! Do the P300 and P400 rear calibers use the same brake pads?

 

You are correct -- because of weight transfer under braking loads, the front of the truck, which is already much heavier than the rear because of the engine and transmission, gets even heavier, The same principle that wants to send you over the handlebars of your bike when you are braking hard. And well-designed brake systems take this into account, sizing the front discs and calipers larger than the rears, and often going with more pistons in the front. Pad size is certainly one part of the equation as well. Also, there is a proportioning valve in the system that sends a certain amount of the hydraulic force generated by the master cylinder to the fronts and a lower proportion to the rears. This ensures that both ends will get the appropriate gripping force relative to how hard you are mashing the pedal, and that (at least in pre-ABS days) the lightly-loaded rears don't lock while the fronts are still rotating, resulting in flat-spotted rear tires.

I say all that to say there's a whole lot that goes into brake system design, and many thousands of hours of testing and tuning at the mfg. level, and I'm always reluctant to monkey with anything other than pads, which, if changed out all around, shouldn't mess with any of the proportions.

Here are the front and rear brakes for a GT4. You can see the front 6-piston calipers in the back and the rear 4-piston calipers in front. And the discs are just the opposites, with the big fronts close to the camera.

 

This really isn't rocket science. There's a reasonable chance that L8's off market brakes are made by the same manufacturer as LR OEM brakes. That happens all the time in the auto aftermarket. Land Rover usse the bigger brakes, because they are better, in that they don't fade as much over multiple braking attempts, because they dissipate heat better. And let's face it, 'the masses' just like bigger brakes...
Under normal use, I suspect there is minimal difference if any of stopping distance. For example the specs for the LR3 stopping distance and the LR4 with bigger caliper are both around 130' from 60 (60?). And I'd never even attempt to explain why the rear brakes wear out faster than the front on every single LR I've owned, but they do. LOL.

What I'm wondering is if there is something special about the Tuffant wheels and their offset, or will their smaller calipers allow any 18" wheel, such as the steelies?

 

Thanks, @NoGaBiker ! Great answer & pics. Much appreciated. I'm willing to go all in, but I'm going to wait for some brave soul to set it up first.

 

FYi, the part numbers i listed above replaces the stock P400 350mm calipers (20 inch wheels) with a smaller caliper. These are actually the same calipers that come stock on the defender with 22in wheels (though those have larger 380mm rotors). Brake pad and everything else is the same. This allows you to fit the tuffant 18 in alloys, no idea on steel wheels.

M

 

Not sure if they fit with the caliper conversion, but Tuffant steelies in ET27 offset fit my p300 perfectly. Might be worth a try if you want steelies at a much lower price than OEM. No spacers and the OEM TPMS fit perfectly. $925 for a set of 5. I was able to sell my OEM wheels for more than the cost of the tuffants.

 

Correct me if I’m wrong, but aren’t those part numbers for 20” wheels?
Wouldn’t you need calipers for 18’’ wheels? (LR102242, LR102245).
Are the brake carriers also needed? (LR102239, LR102241)

(part numbers from rimmerbros.com)

 

For those that have done the caliper swap is it as straight forward as described.

Take wheels off

Take rear calipers off

Put on smaller rear calipers

Put on 18" wheels

*TPMS to taste

Watching Defender mod videos gives me the heebeegeebees when a thousand bolts get undone and a dremel saw appears to change a rubber mat.

 

As I continue to figure out the LT tires to put on my P300 D110, I need to check on my understading of spacing.

DEFENDER OFFSET IS ET41

Using Tuffant steelies .... Weight: 18kg

- Load Rating: 1000kg

- Offset: ET27 or ET44

- Size: 18" x 8"
-------------------------

Is this what happens using the Tuffant wheels?:

ET27
14 mm = .55 inch - tire moves outward

ET44
3 mm = 0.12 inch - tires moves inward

What are the pros/cons of not exactly hitting the OEM offset number? ARE THERE RULES OF THUMB ON SUITABLE OFF-ROAD VARIATION?

 

I think the Tuffant Steelies ar 8"

The reduced 0.5" with the inner aspect of the rim rim being 0.25" (12.5mm) further away from the inner workings might equate to a 39.5mm offset in an 8.5" rim so pretty close to OEM spec. (41)

Maybe I'm way off in my thinking