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01-12-2016, 10:07 AM | #23 | |
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01-12-2016, 10:12 AM | #24 | |
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The fact that Drivehard has everything you need to bolt it up, this would be a great upgrade for a street driven car and is completely bolt on and factory. NOTE: I'm not affiliated with or even know Drivehard, just stating facts here so no bias from me, buy whatever you want |
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01-12-2016, 10:41 AM | #25 | |
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On the other hand, you get more braking power with less effort on the brake pedal |
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01-12-2016, 01:01 PM | #26 | |
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01-12-2016, 01:38 PM | #27 | |
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some background. as asbrr said above this is 100% true.. the Kit I have was SOLD by BMW for 128's to be upgraded to "135" Brakes and yes the rear caliper piston is slightly larger to help with the brake bias. No Need for the Bigger master as per BMW engineers. BUT there was a retrofit coding to the DCS that the kit came with when I got it. It can be done to any 128. other "upgraders" did not do the retrofit and had no issues. I even have my F30 backing plates to help with cooling as insufficient cooling was the death of theses calipers. The pedal feel and response was amazing I really enjoyed driving the car with the "big brakes" carry on..
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01-12-2016, 08:11 PM | #28 | |
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"if your going to use your car on the street, a pad upgrade is all you need. If your going to use it at the track (using the brakes over and over in a short amount of time) and want to avoid brake fade, boiling fluid, etc, upgrading may be worth it" Btw: my stepfather's stock 1984 318i was NOT track ready. |
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08-11-2020, 03:24 PM | #29 | |
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Bumping this to see if anyone has gotten any new info.
The 128i is currently Front Caliper Piston: 54 mm (2290 mm^2) Front Rotor: 300x24 mm (consider this base leverage) Rear Caliper Piston: 42 mm (1385 mm^2) Rear Rotor: 300 x 20 mm The F30 335i with Grey Brembos is: Front Caliper: 2 x 40 mm (2513 mm^2 = 9.7% more force) Front Rotor: 340 x 30 mm (consider this 20 mm larger lever arm = 170/150 = 13% more leverage) UPDATED NUMBERS F30 Front pistons are 40 mm: Quote:
We have an estimated 25% imbalance to make up. A little less than Suprgnat estimated but still a lot. T2/T1 = 1.097*1.13. If the rears are 45 mm, then you need a 50 mm piston to make that up. So how can we get the bias back? What about the E90 328 rear calipers that are offered in the E82 performance brake kit? What is the E90 rear caliper piston diameter and what is the stock 128i caliper piston diameter? EDIT: I got the rear 128i piston diameter. It is 42 mm. The rear E90 328i caliper piston is 44 mm diameter with the same rotor and mounting bracket. So that's an increase from 1385 mm^2 to 1520 mm^2 which is about 10%. That makes up for the area disparity between the F30 pistons and the old 128i pistons, but doesn't address the rotor diameter and increased leverage.
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Last edited by WDE82; 08-11-2020 at 06:22 PM.. |
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08-11-2020, 06:16 PM | #30 | |
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What I have is: Stock 128i, 62.72/37.28 (300x54F, 300x40R) F30 Fronts, 68.29/31.71 (340x2*40F, 300x40R) F30 Fronts, BMWP Rear, 66.14/33.86 (340x2*40F, 300x42R) Stock 135i, 64.93/35.07 (338x(28+32+36)F, 324x42R) Get the (equivalent of) the BMW Performance calipers for the rear. Cheap and easy. Go from a 40mm to 42mm rear piston diameter. Rebuilds are $45 each at Rock Auto (+core). They came on the E-generation 328i among others, so there should be gobs in the junk yard, too. Left Rear: 34216768697 Right Rear: 34216768698 Also, I highly recommend brass guide bushings. I had them front and rear at one time with the 42mm calipers in the rear and 330x24 discs up front with 34116769097 caliper carriers and the stock 54mm front calipers. Very nice combination. I used 34116794427 330x24 front discs from the E89 Z4. They're built the same way as the 135i front discs, i.e. aluminum hat riveted to the disc
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08-11-2020, 06:26 PM | #31 | |
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Could you share the excel sheet if you don't mind? I was just sitting here with my iPhone and doing the numbers. I could've easily made a big error. I may work on a sheet real quick too. I think I'll get them because it takes care a big chunk of the bias change and yeah they're super cheap. I'll send my 128i calipers in as the core. They won't notice the difference.
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08-11-2020, 06:29 PM | #32 | |
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Missed this.
No, it's 40mm. The performance caliper for the 128i are 42mm and the same as found on some 328i. Quote:
Do the rear narrow hub conversion and you can throw on anything that fits on a 335i, which starts at 336x22 with a 44mm piston caliper.
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08-11-2020, 06:34 PM | #33 |
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PS, look at your calipers. The size is cast right into it "40/20". Sometimes the fronts will include the disc diameter.
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08-11-2020, 06:49 PM | #34 | ||
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Yeah clearly the immediate answer is to go with the 328i caliper since it's going in the right direction. That's interesting about the cast numbers. I had never noticed. I'll have to look next time I have the wheel off. When you did your bias sheet, did you measure/estimate the effective radius? That's the only thing I'm fudging at the moment. Here's those cast letters on the E90 caliper!
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08-11-2020, 07:03 PM | #35 |
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Most measured, some estimated. Specifically the Re for the F30. I don't remember my sauce, but I used Re=140mm
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08-11-2020, 07:18 PM | #36 | |
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I'm making offers on rear calipers tonight haha.
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08-12-2020, 08:39 AM | #37 |
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I haven't run the numbers, but I'm wondering if I originally did the calc fot the 370mm discs.
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08-12-2020, 09:16 AM | #38 |
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That combined with 42mm x2 pistons would probably get you to that large difference.
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