BMW 1 Series Coupe Forum / 1 Series Convertible Forum (1M / tii / 135i / 128i / Coupe / Cabrio / Hatchback) (BMW E82 E88 128i 130i 135i)
 





 

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      01-12-2016, 10:07 AM   #23
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Quote:
Originally Posted by Horigan View Post
Has someone actually put bigger piston calipers on a 128 and liked the pedal feel? Seems like you would need the 135i master cylinder also to maintain good pedal feel. Matching larger brake pistons with a small master cylinder piston will result in a soft pedal...

Rich
Agreed on the theory....but the upgrade from a sliding caliper to a 1 piece caliper like the 135i makes for a huge difference in pedal feel IMO even without touching the master cylinder (saying this from empirical/personal evidence after the swap). After all, BMW sells these calipers as part of their upgrade kit for the 128i, so they must have done the math/work to ensure it is compatible with the stock 128i master cylinder.
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      01-12-2016, 10:12 AM   #24
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Quote:
Originally Posted by cpnbnanamn View Post
So, the next question.. What's the difference between the kit that DriveHard has and these?
http://www.turnermotorsport.com/p-18...e91e92e93.aspx

I know these are stupid questions.. But as I mentioned, I don't want to go jacking with things without having solid information.
Drivehard's kit is the true 128i kit. The front calipers will be the same as the Turner kit except the Turner kit will be grey vs the yellow ones in Drivehard's kit. The rear option from the Turner link is for the 135i calipers, those fit on a 128i BUT YOU LOSE THE E-BRAKE. The kit Drivehard has is meant for a 128i in that it is a full bolt on without losing any functionality. The rear calipers are visually the same as stock, but have a larger piston to help with overall brake bias. These are the same calipers used on a 328i rear as well, hence this is why I mentioned you could buy used 328i rear calipers to "make your own kit".

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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Quote:
Originally Posted by asbrr View Post
Agreed on the theory....but the upgrade from a sliding caliper to a 1 piece caliper like the 135i makes for a huge difference in pedal feel IMO even without touching the master cylinder (saying this from empirical/personal evidence after the swap). After all, BMW sells these calipers as part of their upgrade kit for the 128i, so they must have done the math/work to ensure it is compatible with the stock 128i master cylinder.
Reality follows theory, if theory is right! In this case pedal travel on a 128i with performance brakes is longer than on 135i with stock brakes. It's not a night and day difference, but you can feel it.
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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Quote:
Originally Posted by AlexR6 View Post
Reality follows theory, if theory is right! In this case pedal travel on a 128i with performance brakes is longer than on 135i with stock brakes. It's not a night and day difference, but you can feel it.
On the other hand, you get more braking power with less effort on the brake pedal
Sure - but to be honest I haven't noticed longer travel (I only have the 6 piston front calipers, haven't upgraded the rears yet). Pedal is responsive, firm, and as you mentioned much more braking power!
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      01-12-2016, 01:38 PM   #27
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Quote:
Originally Posted by asbrr View Post
Drivehard's kit is the true 128i kit. The front calipers will be the same as the Turner kit except the Turner kit will be grey vs the yellow ones in Drivehard's kit. The rear option from the Turner link is for the 135i calipers, those fit on a 128i BUT YOU LOSE THE E-BRAKE. The kit Drivehard has is meant for a 128i in that it is a full bolt on without losing any functionality. The rear calipers are visually the same as stock, but have a larger piston to help with overall brake bias. These are the same calipers used on a 328i rear as well, hence this is why I mentioned you could buy used 328i rear calipers to "make your own kit".

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
Hello all.. Wow a blast from the past. Now I know why the PM's lol ..

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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Quote:
Originally Posted by hoki06 View Post
I wish people would stop saying junk like this. Throwing out advice such as the quoted statement is what perpetuates the idea that you have to mod your car to be "track ready" before getting on track.

ANY stock BMW is perfectly suited for a beginner to get on track and learn. Any car will have capabilities well beyond a novice driver's skill set for the first several days on track. The notion that you have to swap brakes or have sticky tires or upgrade to xyz suspension before getting on track is absurd and actually hinders the novice driver's ability to learn.

If someone actually cares about learning to drive and not blowing their money, the best thing to do is take whatever money they were going to spend on mods and buy some seat time. Seat time in a slow, bone stock car is the best way to increase ones driving skills IMO. Once they start outdriving the car (brake pads, not rotors/calipers, are probably the first item to address) then modify the car to address those areas.

This is not anything directly aimed at Fast.asleep, just something I consistently observe on multiple forums I frequent.

/rant
Ok let me put it a different way,

"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:
Originally Posted by WhatsADSM View Post
As an update for anyone that reads this... They are 40mm front pistons, which is great because mathematically it only changes the bias like 5% (and forward) versus the 135i setup.
F30 Rear is irrelevant IMO since they don't fit.

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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      08-11-2020, 06:16 PM   #30
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Quote:
Originally Posted by WDE82 View Post
We have an estimated 25% imbalance to make up. A little less than Suprgnat estimated but still a lot.
Funny, this made me pull up my Excel bias calculator and have a far different number than that earlier post.

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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Quote:
Originally Posted by Suprgnat View Post
Funny, this made me pull up my Excel bias calculator and have a far different number than that earlier post.

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
In that case the only number I had that disagrees with yours is the 128i rear piston size which is said to be 42 mm. I got a bunch of new info like 10 mins ago so read the edited post. Also the E90 328 rears are 44 mm.

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.

Quote:
Originally Posted by WDE82 View Post
I got the rear 128i piston diameter. It is 42 mm.
No, it's 40mm. The performance caliper for the 128i are 42mm and the same as found on some 328i.

Quote:
Originally Posted by WDE82 View Post
I The rear E90 328i caliper piston is 44 mm diameter with the same rotor and mounting bracket.
328i is all over the place, but most I see are 300x20 with 42mm calipers.

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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Quote:
Originally Posted by WDE82 View Post
In that case the only number I had that disagrees with yours is the 128i rear piston size which is said to be 42 mm.
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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Quote:
Originally Posted by Suprgnat View Post
Missed this.



No, it's 40mm. The performance caliper for the 128i are 42mm and the same as found on some 328i.



328i is all over the place, but most I see are 300x20 with 42mm calipers.

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.
Quote:
Originally Posted by Suprgnat View Post
PS, look at your calipers. The size is cast right into it "40/20". Sometimes the fronts will include the disc diameter.

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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Quote:
Originally Posted by WDE82 View Post
When you did your bias sheet, did you measure/estimate the effective radius? That's the only thing I'm fudging at the moment.
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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Quote:
Originally Posted by Suprgnat View Post
Most measured, some estimated. Specifically the Re for the F30. I don't remember my sauce, but I used Re=140mm
Ok great, so I would expect us to have some difference in our numbers.

I'm making offers on rear calipers tonight haha.
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      08-12-2020, 08:39 AM   #37
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Quote:
Originally Posted by WDE82 View Post
A little less than Suprgnat estimated but still a lot.
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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Quote:
Originally Posted by Suprgnat View Post
Quote:
Originally Posted by WDE82 View Post
A little less than Suprgnat estimated but still a lot.
I haven't run the numbers, but I'm wondering if I originally did the calc fot the 370mm discs.
That combined with 42mm x2 pistons would probably get you to that large difference.
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