E34 M50B25 manual conversion

[HamishNZ 1]

Hi my fellow NZ'ers!

I am wishing to convert my auto E34 525i with the M50B25TU (Vanos) into a manual.

I am finding it difficult (not suprisingly) to find the getrag 250 + conversion kit that came standard on the late model 525i's with the M50 engine.

The earlier models with the M20 engine have the getrag 240's or 260's (or zfSG310?) i believe and these seem to be more available.

I've heard that the M20's gearbox bolts up perfectly to the M50 but due to the M50's tilt the box is on a 10degree tilt and therefore doesn't align with the gearbox mounts.

Is anyone familiar with the process required to modify the mounts to suit the older gearbox?

Or even better, if you can buy these pre-made?

Oor even BETTER, does anyone have a maual conversion kit for my M50 E34?

Any help will be greatly appreciated!

Cheers

Edited June 19, 2015 by HamishNZ

[Driftit 2078]

It is the same box as the e36 is it not? Try Brent at BmWorld.

Adjusting mounts and angles would not be cost effective.

Sent from my GT-P5100 using Tapatalk 4

[_ethrty-Andy_ 2132]

use the correct gearbox for the car. playing around with modified brackets etc means you will need to certify the car, and thats more cost and hassle than is necessary.

Even in the E34s day, there weren't many that chose manual so conversion kits are hard to come by

[BM WORLD 1283]

e34 525i m50 use the sleightly larger ZF box and most where the overdrive version .

a getrag 250 will do or a zf with the 1:1 top gear will do , but you do have to muck around with gear lever parts etc .

i have kits from e39 528i , e36 , z3 e46 etc . have a e34 pedal box , and some other bits , but not a complete e34 kit.

but most small parts can be brought new and a drivehshaft can be made to suit

[Ahmedsinc 414]

Custom driveshafts will require certification + hoops etc. Might be less expensive to find a manual & strip it for parts for yours

[HamishNZ 1]

*update*

I used a getrag 250 from a 93 E34 520i

I used the front half of the manual driveshaft with the rear half of the auto driveshaft so I could keep the auto diff - because the wreckers broke the mount on the manual diff with their forklift.. rookies lol

[_ethrty-Andy_ 2132]

how does the RPM sit at 100 with the auto diff? probably over revving a wee bit?

[KwS 2424]

the rpm at 100kph on my E36 with manual box and auto diff was terrible, over 3000rpm iirc. Made for some damn quick getaways though!

[No name user 379]

used a 260 box behind my M50 with a auto 4.1 diff

sits on 3200 at 100kph not a big deal since i run it to 8500, youll be hard pressed to find all the bits here however Ebay england is pretty easy

[HamishNZ 1]

100km/h sits around 3200RPM, 92km/h @ 3000RPM.

So I usually cruise just under a hundy, which everyone seems to do these days anyway..

plus most of the 100km zones where I live have been reduced to 80kms.

I don't mind though, it makes 2nd gear very snappy which suits my driving lol (keep it to the hills)

Wish I had the money for a turbo like yours crunchy, what a beauty! idk how you're headgasket survives, mine blew @ 180,000kms

I've seen a few Toyota SC14 Superchargers for a couple hundy bucks; contemplating whacking 1 where the air conditioning compresser was. Apparently it'll make about 6PSI with the standard pulley which will be fine with standard injectors/ECU?

Bit worried about it running lean tho, maybe use a resistor or something to trick the MAF sensor into thinking the air is colder/more dense than it really is, so it will compensate by squirting more fuel?

I think I saw someone on here with a similar project, would be great to have a template of some sort to copy the mounts. I'm thinking you'd want some kind of tensioner so you could ensure the belt doesn't slip on the supercharger.

Edited June 29, 2015 by HamishNZ

[No name user 379]

Youll get away with stock injectors to 6psi , uses a Apexi S AFC for the MAF to add a bit more control and keep cost down.

Mines done 260,000km on stock head gasket running 11.8psi at 500hp, its all about control that makes them live

[HamishNZ 1]

Cheers crunchy, so use an Apexi SAFC with an air fuel ratio gauge to get the ratio close to 14.7?

Are the older ones any good with the analogue dials? 1600rpm incriments seems alot/inaccurte, although i assume it makes a curve with the given values.

Here's one going cheap on trade me:

http://www.trademe.co.nz/motors/car-parts-accessories/performance/electronics/auction-923648647.htm

[No name user 379]

Cheers crunchy, so use an Apexi SAFC with an air fuel ratio gauge to get the ratio close to 14.7?

Are the older ones any good with the analogue dials? 1600rpm incriments seems alot/inaccurte, although i assume it makes a curve with the given values.

Here's one going cheap on trade me:

http://www.trademe.co.nz/motors/car-parts-accessories/performance/electronics/auction-923648647.htm

The 5 button one works fine just set the dip switches to the car as in 6 cly etc the manual is on the net if you hunt,

Dont get hung up on the number for mixtures you need to give the motor what it wants not what the text book says, also if your running a 02 sensor you'll need to disconnect or the ECU will try and fight the AFC.

The settings of 1600rpm are fine remember they are all connected together, all the buttons are doing is lifting the curve up and down at set points the unit works the rest out, i use to use them on turbo cars without a issue only time they are not ideal is you can set the mixture at 3000rpmm for cruz and itll be the same for 3000rpm with boost so its a compromise but its also alot cheaper than other methods.

[HamishNZ 1]

Is the standard E34 M50 O2 sensor wideband or narrow? (I'll need a wideband sensor for AFR gauge)

Since the AFC only 'mimics' the MAF's signal with a percentage in/decrease,
eg. AFC set to +10% = DME signals injectors spray 10% more fuel,
should I then 'tune' it at WOT?
Assuming this is the most leanest throttle position, I can handle a slightly rich cruise (I hardly cruise)

AFR: I think I'll aim around 12:1 then lower it to 11:1 as RPM increases (rich reduces temp/detonation)

On the back of the AFR module it has:
TYPE SELECT (8 switches up or down) &
CAR SELECT (1-9)

I can't find any info on what settings I should use..

Here's the manual:
http://www.kcar.org.hk/docs/safc_gen1o.pdf

[No name user 379]

Stock 02 is a narrow band you cant use it for tuning

Like i said, i dont stick with a number for tuning i give the car what it needs whatever that number might be, running 11/1 afr is rich enough to run some serious boost up it.

You need a wide band meter of sorts like Innnovate LM1/2, you leave all the AFC buttons in the 0 position to start with, if you have never tuned before i suggest you got to a reputable tuning guy.