[Twenny]

They are both 3 litre motors. Basically the same engine, but BMW restricted the power of the 125i so that it did not threaten sales of the 135i. Consequently, the 125i can be remapped to produce about 265bhp - the same as the 130i.

The 125i has smaller brakes than the 130i. This too, is a relatively cheaply addressed by swapping parts.

The 125's have smaller brake discs yes, but the calipers are the same size so stopping power isn't improved, just less fade on heavy prolonged braking.

Not convinced that's entirely true. Yes same caliper/pads will mean the same braking force/pressure on the caliper, but on the 130 it's being applied approx 10% further from the hub/wheel centre so creating greater braking torque surely? If it were the case that rotor radius/diameter made no difference to brake force no manufacturers would ever fit larger diameter rotors. They'd just make them thicker (more massive) to deal with the extra heat.

Hey I'm just quoting from people bigger and better than myself -

https://www.babybmw.net/forum/viewtopic.php?t=63521&start=45

Around half way there's a deep discussion about brakes/discs/heat etc etc

 

[Twenny]

Think he now has the M135i Brembos on the front another fairly cheap upgrade these days

Think he now has the M135i Brembos on the front another fairly cheap upgrade these days

Yeah I didn't want to confuse things mate but you're right he now has a lovely set of Brembo's on

Oh I do I do I do I do - (in a Lion from the wizard of Oz voice)

 

[Twenny]

Hey I'm just quoting from people bigger and better than myself -

https://www.babybmw.net/forum/viewtopic.php?t=63521&start=45

Around half way there's a deep discussion about brakes/discs/heat etc etc

Ironic thing about that discussion is that everyone was correct:

Tyres are the actual limiting factor in just how much actual deceleration is possible for the majority of road cars. Nearly all road cars can overcome the grip of the tyres with their standard brake set up, no surprise there as that's what the manufacturer designs them for.

Larger brake discs and/or caliper pressure/brake pad area will generate higher maximum braking torque on the wheel, so assuming you don't change the master cylinder to compensate you'll need less brake pressure to achieve the same braking torque at the rotors. So the brakes feel more powerful, because they are.

Larger brake disks are (usually) more massive (read heavier) and so can absorb more heat energy for the same rise in temperature and so fade less/later under extreme use.

If you were to fit a the largest full race set up from a company like AP Racing on a car with skinny 205 all weather tyres you'd have so much braking force the car would be almost impossible to drive at urban speeds without locking up all the time. Assuming the wheel size was large enough to fit the 410mm brake disks of course.

Read headed section "disc diameter":

https://www.apracing.com/Info.aspx?InfoID=34&ProductID=1967

Few people know more or have more experience about brakes than AP Racing.

Hmm interesting.

Like I said, bigger and better than myself, so I'm happy to acknowledge you could be right but not too loudly.

The 130i brakes did feel better than my OEM Set up although they still faded badly at Bedford after a few heavy braking laps.

 

[golfer]

Oh I do I do I do I do - (in a Lion from the wizard of Oz voice)

Oh ! I thought you were quoting ABBA

 

[Twenny]

Oh I do I do I do I do - (in a Lion from the wizard of Oz voice)

Oh ! I thought you were quoting ABBA

Nah Knowing me knowing you.

 

[Twenny]

Hmm interesting.

Like I said, bigger and better than myself, so I'm happy to acknowledge you could be right but not too loudly.

The 130i brakes did feel better than my OEM Set up although they still faded badly at Bedford after a few heavy braking laps.

You need these:

https://www.apracing.com/product_de...ig_brake_kits/bmw/z4_applications/z4m_coupe_front-6_piston_kit_cp5575-1010.aspx

Only $5k

http://www.modbargains.com/AP-Racing-Formula-Big-Brake-Kit-E85-Z4.htm

Money money money

(That was ABBA lol)

 

[golfer]

Money money money

(That was ABBA lol)

Yeah ..... so was "I do I do I do I do I do"