Its a rear big brake kit Jim, but not as you know it!
- Thread starter B21
- Start date
B21
Lifer
The epic story continues..
Despite lots of testing on a rig, as usual the real world bits..
The slightly modified location and the different location of the feed point on the the 5 series rear calipers means extra long hydraulic pipes..
Also a pitfall of stainless braided pipes is a poor bending circle so the routings need modification…
And to emphasise the ping about subtle differences..
Why is there at least 3 ways to route a hose straight after the caliper ..the bracket mounted to the back of the caliper
Here are 3 versions..E89 right, F10 centre M5 left of a simple clip..only the E89 works for us..
Despite lots of testing on a rig, as usual the real world bits..
The slightly modified location and the different location of the feed point on the the 5 series rear calipers means extra long hydraulic pipes..
Also a pitfall of stainless braided pipes is a poor bending circle so the routings need modification…
And to emphasise the ping about subtle differences..
Why is there at least 3 ways to route a hose straight after the caliper ..the bracket mounted to the back of the caliper
Here are 3 versions..E89 right, F10 centre M5 left of a simple clip..only the E89 works for us..
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dumaurier7
Member
B21 said:
i'll be interested in the 370mm kit for my Euro 35i!
:rofl: :driving:I've seen online (cant find it now; sods law) someone retrofitting g30 m sport rear calipers with f10 345mm rear discs.
BMW also offer the same calipers unpainted as standard on some of the g30 models.
Is there any chance your adpator would fit this caliper?
I ask because this caliper uses the same spec discs as the f10 caliper in your kit (pdc & hat will differ. Ears maybe?), however is far more widely available.
Extremely common on the used market, with the added benefits of being newer, less worn, already painted blue with the m sport badge.
BMW also offer the same calipers unpainted as standard on some of the g30 models.
Is there any chance your adpator would fit this caliper?
I ask because this caliper uses the same spec discs as the f10 caliper in your kit (pdc & hat will differ. Ears maybe?), however is far more widely available.
Extremely common on the used market, with the added benefits of being newer, less worn, already painted blue with the m sport badge.
B21
Lifer
mittu said:
That initial version turned into a nightmare if it’s the G30 caliper..the OP used some CSL front discs ..it turned into a Vietnam with so many modifications required to pads, calipers, knuckles etc..
The F series 5 calipers are readily available both as OE and other suppliers
B21
Lifer
I had an issue with one of my brake carrier bolts backing out…maybe caused by the stress of the uprated rear brake, maybe cause I didn’t use the old caliper cradle bmw bolt which has some primitive antilock washer fitted..maybe because I’d remounted the caliper cradle several times the loctite had worn off..
So using these fancy nord lock washers in super harden steel..arguably the best anti vibration washer…
Fresh 10.9 high tensile bolts…double locked the through bolts..
Did try the wire lock strategy but close to impossible to drill the bolt heads to allow the wire to be threaded..
Lots of medium strength loctite this time..
So using these fancy nord lock washers in super harden steel..arguably the best anti vibration washer…
Fresh 10.9 high tensile bolts…double locked the through bolts..
Did try the wire lock strategy but close to impossible to drill the bolt heads to allow the wire to be threaded..
Lots of medium strength loctite this time..
Attachments
B21
Lifer
Version 3 of the rear brake caliper adaptor for the 370mm rear disc conversion using a standard F series 5 caliper…
After discussions with a brake caliper bracket guru thickened the bracket from 12mm to 15mm in S355 steel…..
This will allow me to machine a mm or so off this bracket to allow it to bolt the caliper cradle up without having to use any spacer washers..plus..
This version allow for the 370mm version to machine the caliper cradle without having to machine out the entire gap between the front and rear mounts
After discussions with a brake caliper bracket guru thickened the bracket from 12mm to 15mm in S355 steel…..
This will allow me to machine a mm or so off this bracket to allow it to bolt the caliper cradle up without having to use any spacer washers..plus..
This version allow for the 370mm version to machine the caliper cradle without having to machine out the entire gap between the front and rear mounts
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The.Analyst
Member
Is it debugged yet ?
B21
Lifer
The.Analyst said:
Several iterations
Base idea was based on an idea published my P Morelli and A N Other on US based BBs.
Two different 3 series F upgrade caliper brackets were purchased to see how they did it.
Based on one of those I created a variation that addresses the unique issues on the E89..ie old E85 style rear suspension but electronic parking brake from the 5 series.
Two versions one for 345mm old 5 series E rear disc and a 370mm 7 series F rear disc. Same caliper different adapter bracket.
Some iterations to get the pads to line up perfectly with the available swept area of the discs.
All the adapter brackets we saw used ‘standard’ size holes for the bolts..ie for 12mm bolts 13mm holes.
What we found is that there is too much slop in those sizes compounded by the fact that we are using 4 bolts now not 2
The stock hold clearance BMW uses is much tighter..about 0.5mm vs 1mm.
Advice from folks who have built many of these brackets across a wide range of cars is to try and get that as tight as possible.
We’ve taken it down to 0.3mm and about to try 0.0 (screw threads on bolt just under 12mm)
Also the design relied on spacer washers to align the caliper cradle with the disc..different disc offset different thickness of washers.
All these issues means there is a considerable loosening torque on the bolts.
The first long road test had to be cut short as the caliper cradle bolts were loosening off..
In part due to a lack of a proper lock washer like bmw used, in part due to lack of loctite, in part due to loose hole sizes and inpart due to lack of torque on the bolts as the washers settled down.
So our next iteration is a 15mm thick rather than 12mm thick design with milled areas to obviate the need for spacers..plus Nord lock washers, tighter hole tolerances and use of 12.9 rather than 10.9 bolts and nuts.
In addition it looks with the 370mm version that the caliper cradle can be milled to gain enough clearance rather than a piece cut out of it…which will please some folks ..
B21
Lifer
For my 340/370mm big brake kit just had turn number 5 from the laser cutters..
Reduced slop in the mounting holes..stock ‘tight’ fit is 13mm..then went to 12.3mm now 12mm
Two design changes…increased thickness to 15mm to allow for some milling of the bracket and retain thickness..
Done another turn down to 12mm exact...amazing all bolt holes line up and 12mm bolts go through…onto the next stage…milling the offset required to remove the need for spacer washers in the installation…
Reduced slop in the mounting holes..stock ‘tight’ fit is 13mm..then went to 12.3mm now 12mm
Two design changes…increased thickness to 15mm to allow for some milling of the bracket and retain thickness..
Done another turn down to 12mm exact...amazing all bolt holes line up and 12mm bolts go through…onto the next stage…milling the offset required to remove the need for spacer washers in the installation…
Attachments
B21
Lifer
My E89 rear big brake kit (345mm/370mm) continues..after input from a long experienced kit car builder / sports car renovator I’ve re-iterated the adapter bracket…up from 10mm to 15mm thick, 12mm bolt holes down from 13mm to 12mm and milled mounts to obviate the need for spacer washers..prototype development at an old friend’s workshop with a recalcitrant old milling machine…FWIW the original bracket I used for a basis used on E90s has none of those features..
