w124 4sp to 5sp Auto conversion

[aka$h]

Im just about to buy a car with a 5sp auto to swap the gearbox and diff over. Nav just had a word with george, and apparently there is an electrical plug on the 5sp box, which mine wouldnt have.

Does anyone have any more info on what additional wiring would have to be done? Or if its even worth bothering with?

Thanks

 

[fnkhan68]

my personal opinion but why would you want to change from a reliable 4spd hydraulic gearbox to a not so reliable partially electronic 5 spd gearbox. most of the few e36 amg's i have seen are 4spd plus the monstrous 500e only came in 4 spd, must be a reason. if you are going to do alot of motorway mileage then you will benefit from the upgrade but it seems unlikely as im sure you dont want to be piling on the miles on your stunning coupe. my opinion is leave it.

 

[Dieselman]

If you think your car is undergeared just fit a higher ratio diff. I would be surprised if the 5 speed made any tangiable difference.

Talking of diffs, has anyone got one with the ratio higher than 2.85:1 that they want to part with.
How much is a good diff from the breakers?

 

[bolide]

Speaking as someone who has driven a few 5-speed autos, I reckon they're great

I wouldn't underestimate the extent of the job - but then I wouldn't underestimate the effect of a 5-speed and a decent 280/320 engine. It's a good combination which, when working as it should, always seems to be in the right gear

Nick Froome
www.w124.co.uk

 

[KLP 92]

If you think your car is undergeared just fit a higher ratio diff. I would be surprised if the 5 speed made any tangiable difference.

Talking of diffs, has anyone got one with the ratio higher than 2.85:1 that they want to part with.
How much is a good diff from the breakers?

Diffs normally are between £100-200 roughly depending on the breaker or model of the car.

 

[grober]

The w124 E class owners bible gives 2.65:1 as the standard diff ratio for the automatic E320 saloon,coupe and cabriolet and wagon in the USA. The highest I could find was the E400/400E at 2.24:1 Funnily enough the E500 is listed at 2.82:1 so go figure? (SL BACK END ??)

 

[aka$h]

Diffs normally are between £100-200 roughly depending on the breaker or model of the car.

When I was after a 1:3.69 the cheapest price i had was just over £200, the highest was £400.

Ive been doing some research, it would seem the 5sp box has a seperate control module and a different MSG (ECU) control unit too. All in all, too much hassle, if it ends up costing me £6-700 to do there's no point, I dont use the car enough to justify the saving in fuel or strain on the engine.

 

[SL300-24]

I have owned quite a few Mercs with the 5 speed auto, including 129's and my current E320 Cabrio, and have never had a problem with them. I think it is a great gearbox. I think tales of unreliability are exagerrated....good luck if you go for it.

 

[Dieselman]

When I was after a 1:3.69 the cheapest price i had was just over £200, the highest was £400.

Ive been doing some research, it would seem the 5sp box has a seperate control module and a different MSG (ECU) control unit too. All in all, too much hassle, if it ends up costing me £6-700 to do there's no point, I dont use the car enough to justify the saving in fuel or strain on the engine.

Try ebay.de. There are a number of diffs on there now with prices around the 200-250 euros.

 

[Brabus 300E 3.6]

i have a 300E-24V with a 5 speed gearbox
it´s perfect for the 24V as you will allways be in the right rpms.
the 4 speed is not designed for the high rpm 24Valve edition and therefore the rpm drops a litle to much in every gear for the 24Valve M104 Engine to my opinion.

The reason the 500E only came with the 4 speed is because the 500E useses the gearbox from the S class and they where never made in 5 speed at that time. they came only in the newere model after the W126. i think.

To your question:

The 5 speed auto box is also hadraulic made, it´s only the last 5 gear that is controled elektronikly and thats your biggest swap problem.
you also have to change your speedo instrument because there are 2 plugs at the bag of the speedo and they are not there on yours i think.
the one plug controles changing in to last 5 gear.
if you remove the plug it will never change into 5 because it seems to the gearbox that the car is running 0 Mph.
The cable of the plug is the one that goes to your 5 speed gearbox (very simply to aply)
and the other plug seems to controle the auto pilot because it will not work if that plug is out either but that you wont have to worry of i think.

And then the ECU has a different setup to as descriebed before but this i think you can just change from the other car.

To my opinion its worth the swap because of the shortere gear intervals, leving the engine to stay in the high rps under hard acceleration with way quickere acc.
Standart your car is 0-60 in 8 sec. with the 5 speed. it will do it in 7 sec do to the lower 1. gear.
1 gear changing allready at 37 mph/ 60 Kph at 7K,rpm and with the 4 speed it changeing at 45 Mph/72 Kph at 7K,rpm i think.

but you have to make the job yourself otherwise its not worth the effort.

Sorry for my english (im from denmark )
I drive a 1991 W124 BRABUS 3.6-24 with 5 speed Aut. 285 BHP it´s a lot of fun
you can check it uot here.
http://www.bilgalleri.dk/html/gal_visbil.asp?ID=69175