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BMW Performance rear brakes hub swap?

8K views 56 replies 12 participants last post by  Mike_RS 
#1 ·
I'm looking for a set of BMW Performance callipers for the 125i and I know the rears can be problematic getting these installed and working in an OEM fashion :?

I've looked at various threads for information and I've not seen anybody get these installed yet, It seems the only definite way to get the rears installed is to swap the hubs over to 135i ones, so I'm going to start a list of parts required to get these swapped over and I need your help choosing the right parts to do the install :)

In the diagram below can you let me know which numbers I'll need to do a hub transplant on my 125i? Will I need any parts not shown in the diagram, longer drive shafts etc.

 
#2 ·
I thought the performance calipers would fit but you need a specific disc that's made by BMW to go on and then its all bolt on directly.

Its not as simple as the hub as the 135i had a different size handbrake shoe set up too.

Ian knows quite a bit about this (thetyrant) so hopefully he may chime in.
 
#4 ·
Dont think you will need to change the hubs, coupe models use different rear hubs and discs to hatch models (which is more tricky to get brembos onto rear) so it could be a direct bolt on of 135i discs and calipers for you onto 125i, let me have a look through my notes on discs etc......

Ian
 
#5 ·
Thanks for the info so far guys, would like to hear from anybody who has these installed on a e82.

The guy who is selling a set had them on his 123d, does the 123d have the same rear hub as the 125i?
 
#6 ·
Mike_RS said:
Thanks for the info so far guys, would like to hear from anybody who has these installed on a e82.

The guy who is selling a set had them on his 123d, does the 123d have the same rear hub as the 125i?
I looked into this ages ago and I can't remember the outcome. You need to look on real oem for part numbers and compare them. I think on a 125i you're going to need 135i hubs. But just check the part numbers. If the part numbers on the 125 are the same as the 130, then you can fit the performance calipers you just need to fit the performance discs from the 130i.

Have a look and see what you find.
 
#8 ·
Never got chance to have a proper look today, did see the 125 has the smaller handbrake shoes though so you might need those and relevant backplate etc to do the swap, remind me monday to check in more detail.
 
#9 ·
OK ive had a look at rear disc spec etc for this, from what i can see the 135i coupe rear discs will go onto the 125i coupe rear hubs to go with the calipers, which should bolt straight on also.

However as i mentioned above the 125i has the smaller 160mm handbrake system and this means the drum part inside the rear discs than handbrake works on is 160mm internal diameter, the 135i has 185mm internal handbrake so the 125i handbrake system wont work with 135i rear discs fitted as shoes wont come out far enough to contact drum!, couple of ways to sort this for when fitting 135i rear brakes on the 125i coupe, best way in my opinion would be to get some 135i handbrake shoes and i think only other parts need would be the mounting plate that these shoes clip onto and adjuster screw as all other parts are same according to realoem, but these 2 different sets of handbrake parts ive not seen personally to check if its going to work but i do know from my M135i onto 130i rear brake swap its all pretty easy to bolt on/off, in theory it should be ok and would make the 135i to 125i rear brake swap a piece of cake, someone with a 125i would need to have a play though to check.

Other ways to sort the problem would be either to get a machine shop to fit a sleeve into the drum part of 135i rear discs to reduce diameter, costly to do right and safely i think, or get some thicker handbrake shoes made up with correct diameter etc, but thats not ideal i dont think.

Just to add for those saying fitting performance discs for the 130i hatch etc to sort the issue, i can tell you that this will not work as the hatchback rear discs are much shallower (10mm) offset/height than coupe models.

Ian
 
#10 ·
Thanks for the help Ian, absolutely superb work!

I'll try to do abit more research on the handbrake mechanism and find the part numbers I'll need to do the swap over. If you find any more info on this keep me posted :)

Cheers
Michael
 
#11 ·
No problems glad to help, I looked at so many rear disc etc combinations when doing my M135i rear swap it was crazy!

Looking on Realoem these are part number that are different for E82 135i handbrake parts...

Adjusting screw - 34416851437
Supporting ring brake shoe D=185MM - 34216771430

For reference below are same for E82 125i handbrake parts, but check with your Vin on Realoem to make sure it matches as I just went for random year

Adjusting screw - 34416851438
Supporting ring brake shoe D=160MM - 34216771429

If im right you will just need 2 x 34416851437 and 2 x 34216771430 along with some 135i 185mm shoes from brakeparts.co.uk etc and hopefully it all converts over!

Let us know how you go if you head down that route.

Ian
 
#13 ·
THETYRANT said:
No problems glad to help, I looked at so many rear disc etc combinations when doing my M135i rear swap it was crazy!

Looking on Realoem these are part number that are different for E82 135i handbrake parts...

Adjusting screw - 34416851437
Supporting ring brake shoe D=185MM - 34216771430

For reference below are same for E82 125i handbrake parts, but check with your Vin on Realoem to make sure it matches as I just went for random year

Adjusting screw - 34416851438
Supporting ring brake shoe D=160MM - 34216771429

If im right you will just need 2 x 34416851437 and 2 x 34216771430 along with some 135i 185mm shoes from brakeparts.co.uk etc and hopefully it all converts over!

Let us know how you go if you head down that route.

Ian
This is great and saved me loads of time trying to get my head around the part numbers!

I've noticed the 135i has different springs too when comparing the part numbers, (34410410823 125I) (34410410825 135i)

Do you think I'll need new springs and the retaining screw?
 
#14 ·
Ah yes springs will be longer i guess sorry i missed that, you will need them as well, screw wise if number is different then yes.

The unknown is if the holes in the 125i hub that shoe support plate bolts to accepts the 135i support plate, i think it will but that needs to be checked.

Ian
 
#15 ·
I know this is most likely NOT what you are looking for but the Performance brake kit for the European 116,118,and 120 use the stock rear brakes from the US version 328I. This gives you a bigger rear vented rotor and larger caliper which is a nice upgrade from the little caliper and non vented rotor. I personally was able to source good rotors, fresh pads and good caliper for under $180 US from ebay for my upgrade. When they arrive I will paint them to match the 135I Brembos I have arriving for the front.

I have found that the performance rears for the 125I and 130I use the same rear rotor and upgrade only the caliper 34216768697 and 34216768698 as above.
 
#16 ·
david in germany said:
I have found that the performance rears for the 125I and 130I use the same rear rotor and upgrade only the caliper 34216768697 and 34216768698 as above.
Where did you see this as its incorrect ? rotors are very different between coupe and hatch models so no 130i hatch rear discs (stock or BMWP) would fit a 125i coupe as they are approx 10mm different in height/offset, also the 130i has 185mm handbrake shoes inside rear disc as opposed to 160mm on the 125i coupe.

From what I can see the BMWP brake kit for the 125i (or 128i in usa) coupes doesn't use the brembo 2piston rear caliper like the 130i (and other hatch) BMWP rear kits does over here.

Ian
 
#17 ·
Comparing actual part numbers for the European 118i, 120i, 125i, 130i and US 328i on realoem.com. The big differences start to appear when you start looking at the Diesels. There is always a chance that I am wrong but this is what my search has shown me.
 
#18 ·
david in germany said:
Comparing actual part numbers for the European 118i, 120i, 125i, 130i and US 328i on realoem.com. The big differences start to appear when you start looking at the Diesels. There is always a chance that I am wrong but this is what my search has shown me.
Well something wasnt correct with what you have read, basically the smaller engines 116, 118,120, 125, 128 etc all use the 160mm handbrake drum inside rear discs,this is on coupe and hatch models, however the coupe rear hubs have the drive flange sat approx 10mm further out and hence the discs have a deeper offset/height to counter this.

On the 123d, 130i (both hatch and coupe on 123d) they have the larger 185mm handbrake system as does the coupe 135i so discs are different to suit, again on the coupe models the drive flange position being different to hatch means the rear discs are approx 10mm deeper than hatch to suit.

There might be the odd variation or year where above is different so checking with vin when doing things like this is needed of course.

I went through spec of dozens and dozens of various bmw model rear discs when i was trying to find a rear disc to use on my old 130i when i fitted the F series M135i, ended up with the E39 M5 rears which were close enough for what i needed and just slight trim to pads to make them work.
 
#20 ·
Right thanks to everybody input so far, I've ordered the following Genuine BMW parts.

2x 34416851437 - Adjusters - £5.39 per unit (£10.7:cool2:
2 x 34216771430 - Supporting Ring Brake Shoe - £ 6.13 per unit (£12.26)
1 x 34410410825 - Repair Kit Springs - £17.50

Aftermarket:
Ferrodo - 135i brake shoes - £32

Total for parts - £72.54

I was going to order genuine handbrake shoes but these are like £60+ so I'm ordering some Ferrodo versions for the 135i.

Ian - In answer to your doubts about the Supporting ring fitting, I've checked a few websites and they all refer to the support ring fitting the e82 Chassis (Not model specific) so I imagine this will be a direct swap with my smaller version.

The owner of the brakes I'm collecting on Saturday had the rear discs installed on his 123d Coupe and everything worked perfectly, I imagine after I swap my handbrake shoes everything will be a direct swap with the rears brakes currently on my 125i?
 
#21 ·
david in germany said:
DOH! Hope I will not need to hunt down different rotors when my stuff arrives... :eek2:
Depends what your fitting them to and what they came off ? if you let me know i can check through my data for you :)

Ian
 
#22 ·
Mike_RS said:
Right thanks to everybody input so far, I've ordered the following Genuine BMW parts.

2x 34416851437 - Adjusters - £5.39 per unit (£10.7:cool2:
2 x 34216771430 - Supporting Ring Brake Shoe - £ 6.13 per unit (£12.26)
1 x 34410410825 - Repair Kit Springs - £17.50

Aftermarket:
Ferrodo - 135i brake shoes - £32

Total for parts - £72.54

I was going to order genuine handbrake shoes but these are like £60+ so I'm ordering some Ferrodo versions for the 135i.

Ian - In answer to your doubts about the Supporting ring fitting, I've checked a few websites and they all refer to the support ring fitting the e82 Chassis (Not model specific) so I imagine this will be a direct swap with my smaller version.

The owner of the brakes I'm collecting on Saturday had the rear discs installed on his 123d Coupe and everything worked perfectly, I imagine after I swap my handbrake shoes everything will be a direct swap with the rears brakes currently on my 125i?
Sounds good lets see how you go, you should of got the shoes and springs/fitting kit from brakeparts.com its only around £25 for the lot :)

I think its just the support ring question to answer once you get it all apart, then we will know if further fettling is required or not.

Good luck :)
 
#23 ·
I've got a similar situation, got a full set of 130i / 123d reconditioned calipers ready to go on my e87 118d, mine has 160mm currently but will need the 180mm backing plate for the shoes.

These Calipers are going on this car, even if I have to get parts machined (because my current brake setup is not good enough as it's remapped, and because rear O/S caliper is sticking and squealing randomly).

I'm really hoping that Shoe ring backing plate thing just bolts on.
 
#24 ·
whitenight639 said:
I've got a similar situation, got a full set of 130i / 123d reconditioned calipers ready to go on my e87 118d, mine has 160mm currently but will need the 180mm backing plate for the shoes.

These Calipers are going on this car, even if I have to get parts machined (because my current brake setup is not good enough as it's remapped, and because rear O/S caliper is sticking and squealing randomly).

I'm really hoping that Shoe ring backing plate thing just bolts on.
Hopefully it will just be handbrake parts to change and then the rest should swap over.

Ian
 
#25 ·
Just to add some other info to this thread seeing as its kind of relevant , another member has asked me to check if the E82 135i brembos will fit on the E82 123D, looking at all part number i think this is the only E82 which will take the 135i rear brakes as direct bolt on without issue as it shares same handbrake size etc, fronts fit all models of course.
 
#26 ·
The parts are on order so when these arrive I'll confirm if the backing plates are a direct fit.

I'll try to take some pictures along the way for other members who might want to install the rears on their 125i etc. :)
 
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