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adam73bgt

E34 520i Touring Daily Project

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Great project, love this.

 

Brakes are easy to get wrong. In an ideal world you'd have all four wheels lock at exactly the same time - that way you're using all four tyres to their maximum and getting the most deceleration. The standard setup is basically designed to have enough front bias so that the fronts lock only just before the rears (under all circumstances) - for predictability at the expense of a little bit of performance. You can get a little bit more performance by sending the bias rearward in the E34, but it's balance is pretty good on paper.

 

Brake component sizing is then a question of how much heat they have to reject. You won't get any more braking torque by making the brakes bigger - only increased resistance to fade and warping. If you only make the fronts bigger as a lot of people do, you will likely push the bias further forward and actually get less braking performance overall. Plus a lot more weight on the corners which is exactly where you don't want it.

 

I'd say the best solution is to refurb the calipers so they slide freely and don't stick (maximise the amount of pedal effort that gets to the discs), get some good quality (OEM) vented discs (less likely to warp than cheap ones and will last a long time), run braided hoses (to firm the pedal up a bit), and choose a good quality fast road / light track pad to fit all round (good friction / bite / pedal feel / resistance to heat). I'd go Ferodo DS2500 if you can get it - expensive, but don't be tempted to fit just the fronts as you'll alter the bias. Sourcing bigger OEM kit is going to be quite a lot of work for no real benefit, extra weight - and at the end of the day you still have floppy sliding calipers that are never going to set the world on fire. (Although they might themselves.)

 

If you want to go all out, you can fit two-piece "lightweight" discs from an E60 (the cast rotor floats on an ally bell) and combine with proper fixed opposed piston ally calipers - for perfect bias, a rock hard pedal, and endurance-race winning levels of fade resistance. Or just racecar looks. :)

 

Sorry for the essay. Look forward to seeing more!

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Cheers!

 

No worries about the essay, I'm actually a Brakes engineer for an OEM manufacturer so I get to deal with this exciting stuff all day :lol:

 

If I was doing a brake upgrade I would do both the fronts and rears as otherwise I'd run the risk of altering the brake balance adversely as you say. If going for bigger piston calipers I'd also consider changing the master cylinder as well to keep the pedal effort the same

 

As far as I can see, the 540i brakes aren't much bigger than the 'standard' brakes if at all, but have a wider vent gap in the discs so should be better for cooling. Cooling must have been a concern with the higher speeds of the 540i given the brake cooling ducts in the bumper as well

 

I'd argue against there being no benefit in upgrading to bigger OEM stuff, though for the cost to get M5 oppo piston brakes these days, you're probably not far off getting some properly big aftermarket calipers and discs, so its a bit of a case of diminishing returns with the OEM bits.

 

Good quality parts are a good start as you say, I've heard of DS2500's before and they get good reviews.

 

It all depends on what I end up using the car for really, I'd still like to keep it as a daily so track spec pads that squeal all day will become a nuisance haha, also I'd like to keep running 17" wheels for the time being which obviously limits how big I can go on wheels.

 

The standard brakes aren't too bad to be fair, pedal feel could be better but thats pretty standard for a sliding caliper.

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Good work Adam, makes me feel bad about my car that's been sleeping in a garage for months now !

Speaking of brakes, from a 540 touring owner, I'd say they could be a good upgrade for a car with a smaller engine like yours , specially if you can get your hands on a touring that has vented rear discs. Good luck ;)

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On 9/15/2017 at 7:07 PM, adam73bgt said:

...I'm actually a Brakes engineer for an OEM manufacturer...

 

...whoops! :rolleyes: Been a while since I taught my granny to suck eggs.

 

I agree with your point on cooling - more likelihood of stopping more mass from more speed more often on the 540. Diminishing returns is the thing - for me I would see no benefit in larger OEM because of the cost / work to refurb them to as new and extra mass added. Unless you're planning to work the car hard - in which case I reckon go big or go home.

 

I've done the calcs for going to oppos on my 535. Can't find them off hand, but IIRC you can spec Wilwood Superlites in 6- and 4-pot flavour to work with either the standard MC or (again IIRC) one off an E38 and everything balances up (with a bit more rear bias) quite nicely. Thieves stock them, and they're not mad money. Just hopefully can be made to drop under my 17s also...!

 

I have experience of the DS2500 on my 306. People will say they need some temperature in them but wasn't really an issue for me - one stop and they're fine. No puckered moments. I didn't experience any real noise worth reporting. I did trackdays on them on rebuilt sliding calipers with braided lines and they were fine - pretty good in fact. Compared to some of the EBC horror stories I've seen first hand. Only thing I don't know is how aggressive they are on the discs - didn't do enough miles on them to find out. Soft pad / good disc combo is the way forward I reckon.

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Haha no worries, I'm certainly no expert thats for sure! Those wilwoods look quite nice. When the time comes to sort out the brakes I'll have to blow the dust off some of my textbooks and start doing some sizing calculations haha

 

Interesting to know about the E38 MC, and thats a good point, keeping the brake size within the 17" wheels will probably be the biggest headache with any Big Brake Kit

 

 

Done a bit more work on the car, made a decent start on stripping down my spare rear subframe

 

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So I can start building up a shopping list of all the stuff I'm going to need! Getting the bushes out seems like its going to be fun... as well as getting new ones in..

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The Wilwoods, more than anything else, seem like great value. I've seen them up close at a trade show and had a chat with the rep - they're really quite nicely finished, to a level which belies their price. If you can get access to a machine shop to make brackets, that is. I originally got the idea from a chap in the States who has built a heavily turbo'd 525i. (Many pages to sift through over lunch there!)

 

Subframe bushes - there's a special tool. I believe someone on here hires one out, but this is going back a few years now. Of course one can burn them out but I've never been overly fond of that idea, and it doesn't cure the problem of getting the new ones in.

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Made a bit more progress over the weekend, got the drive shafts and trailing arms off the subframe

 

a69ad8c3e094.jpg

 

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So now I'll clean up the subframe, give it a wire brush and a coat or two of POR15, should leave it looking tidy

 

I also managed to pick up this M Tech II steering wheel for what I thought was a pretty decent price, I gave it a quick test fit on the column of the 525i shell which went well so it'll make its way into the 520i shortly

 

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Edited by adam73bgt

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Had a bit of a hiccup

 

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As I was driving to work yesterday morning, the engine cut out as I approached some traffic lights, odd but not entirely unheard of from my previous suspected ICV issues. Went to restart the engine and carry on but it was running very rough, and seemed to have reduced power

Pulled into a layby and tried to work out what was going on, looked under the bonnet and sure enough the engine was shaking more than an inline 6 should be, also the idle exhaust note was much lumpier than usual

Get back in to see if some turning off and on again, or revving will change the situation. At this point I notice that the temp gauge is firmly in the red at the end of the scale, certainly never done that before!!

Switch it off, fearing the worst, call the RAC. In the meantime I try starting it again, takes a lot of spins before it catches and idles rough again.

By the time the RAC arrive, the engine has cooled, go to start up and its like normal, smooth idle. Coolant was a little low though so head to the nearest supermarket with RAC following in case it turns into a kettle.

Top up water, leave car idling and hold it at revs as well to see if it will overheat. No signs at all of the gauge going anywhere above dead centre. The bottom radiator hose did seem to take quite a while to get warm compared to the top hose.

Oddly, while it was idling and I was chatting with the RAC guy, the engine did suddenly die but idled fine once restarted.

In the end, decide that its best to limp it home, and head to work in the RX-7. Go to start it and it goes back to taking a lot of spins to start but idles fine and drives home fine with no temperature issues.

RX-7 then wouldn't start (flat battery) Ended up hopping on my little Honda 125 to get to work in the end!



So now to work out what is going on with the 5. The way it cut out, coupled with the isolated overheating incident had the RAC chap thinking that there were likely 2 different issues going on. My initial thought when the car was running rough was Crank Position Sensor, possibly going iffy because of heat?

The overheating issue could be thermostat related? Possibly water pump? Was done by previous owner and was apparently a metal impeller job, so should have been fine I'd have thought

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Seems like an a bit of an odd one that. I would imagine that the RAC chap is correct and it does appear as if there may be two different issues going on. I would be far more concerned about the car overheating than cutting out...... You may have even done your head gasket if you are unlucky, but by the sounds of it, you probably got away with it..... :)

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Yeah its strange, I took the car out for a drive last night and it was largely fine. There were no temp issues at all, the only two things were it started a bit lumpy/rough, but that cleared up and smoothed out after about a minute of idling, and then once when slowing down to a roundabout, the rev counter dipped down then shot back up before normalising to where it was, accompanied by a pop from the exhaust so maybe it cut spark briefly?..

 

Because there have been no temp issues since, a stuck thermostat is looking like my first port of call for that issue at least. This engine had blown a head gasket with the previous owner so most of the cooling system had been changed but I'm not entirely sure what quality of parts had been used (although they've lasted fine up till now!)

 

I'm using my other car until I get to the bottom of the issues with the 5 in any case :)

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Been pretty lax on updating this thread as I've not really done anything with the 520i since it broke down, a couple of short drives after the initial breakdown confirmed that it wasn't very happy starting after having been driven a while but the issue was intermittent, so I focused my efforts on getting the replacement engine ready :P

 

I've been very slow working over the winter months though, the M50b25 is still sat in the 525i on my drive but I have got the ECU and engine loom out

 

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Diff has been proving a pain to remove as I think I've rounded one of the hex head bolts holding the half shaft on, so I've left that headache for the time being..

 

I have however sourced the bits I need to make my M50 'b30'

 

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All wrapped up here but its all M54b30 parts like crankshaft, rods, pistons, sump baffle and I also got the intake cam and cam tray. The parts are in pretty good nick from first inspection, but I'm trying to find a machine shop/place that knows M5x engines near me to properly measure the crank etc. to make sure everything is in spec.

 

 

I haven't totally given up on the 520i just yet though! While its been off the road I've been dailying my RX7, which is fun but not the most economical or practical so its going to be for sale soon and I'm hoping in the meantime I'll be able to use the 520i still while I get the 3.0 engine ready. I've got a new crank sensor which I'm hoping will resolve the 2.0 issues so at least I can get it out and use it again!

 

Couple other bits of update while I remember, I sourced some rear suspension bits to freshen up the 525i subframe I've got, gone for Lemforder mounting bushes, poly trailing arm bushes and new dogbones/pitman links. I'll also be getting new ARB bushes to go with the thicker Sport front and rear ARBs which will go on the touring

 

I also got the touring on the 15" BBS which I took off the 525i, as I've been trying to sell the RT's

 

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I think it looks kinda cool with the fat sidewalls, but if the RT's don't sell then they'll go back on at some point, maybe with a colour change to the wheel centres, we'll see

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Smashing, looking forward to seeing this '30! Nothing quite like a pile of new bits...

 

Did you ever get the rear subframe bushes out? I happened on this yesterday, whilst scaring myself silly with pictures of rotten sills.

 

On 8/20/2012 at 11:19 PM, Slooby said:

Anyways, as Dan says this evening he tackled the rear subframe bushes, pretty easy job really with the subframe off, a decent puller, a blow-torch and some large washers...

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Going...

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...going...

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...gone...

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Those big washers? Donated by my Landy project's front axle radius arms :lol:

Once we'd figured out what would do the job it took all of 5 minutes to pop the two bushes out of the subframe. As Dan mentioned the replacements are in the freezer getting shrunk

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Ah I hadn't seen that @TomGC , thats really helpful actually as I've not had a go at removing those bushes yet, my first thought was to cut out the middle with a holesaw or similar then use a hacksaw to remove the remaining rubber but that looks a neat way of doing it as well, may have to invest in a puller :D 

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I always feel a bit medieval when cutting / burning things out, and the possibility of it going wrong is a bit too high for my liking... I'll admit to nicking machined suspension components with the grinder in a previous life!

 

Cut a bush off the front of the E36 a while ago, total pain, never again! The older I get, the more I find myself saying 'come on now, just do it properly.'

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