Mercedes W124 - Gearbox swap from manual to auto

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Wed 7 Aug 2013 10:14
Mercedes W124 - Gearbox swap from manual to auto - Mercedes W124 Indian imports

Does anyone have experience of swapping a manual gearbox with an auto box on a W124?

I love W124's and am considering buying an Indian import, but do not like manual boxes. The car would see me to the end of my days, so re-sale is not a problem. I had a 1994 W124 1994, in 2000 and replaced it with an E Class V6 240 estate in 2007 and regretted it from Day One. Luckily, I gave the W124 to my son who had it for 3 years.

a) How difficult would this task be, with mating up the engine to secondhand auto gearbox, transmission tunnel shape and and the lever/shift when doing the replacement?

b) Does the fact the car is an import increase the insurance premiums.

Any thoughts or experience of such a project would be greatly appreciated.

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Wed 7 Aug 2013 17:48
Mercedes W124 - Gearbox swap from manual to auto - madf

Which engine?

I have read of other's exploits. Key issues are:

1. Engine mating to gearbox may be totally different - requiring a new crankshaft !

2. You may need a new propshaft due to different length

3. The wiring is going to be different and you will therefore either need new wirning(!) or have an experienced auto electrician who knows 124s and can do it for you. I can assure you this may be neither cheap nor easy.

The people who have tried such conversions on other cars had either lots of experience and time on their hands - which meant they could improvise or got 2/3rds along and found some problem they could not solve.

Given that an Indian car is unlikely to meet UK road standards - see lights,emissions , etc. you may also have to convert lighting etc..

Frankly on a 20 year old car,the chances are you will need some parts which are unobtainable new so a scrabbling around scrapyards will be required.. If you end up with any deviation from UK specs, then your car may end up being registered as new - and have to pass modern emissions - which it won't . Ever.

And finally your insurance company will probably insist upon an engineering inspection at your cost before even quoting.

I'd run a marathon before taking on such a scheme.

Edited by madf on 07/08/2013 at 17:50

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Wed 7 Aug 2013 19:51
Mercedes W124 - Gearbox swap from manual to auto - gordonbennet

Presumably you're after a saloon then, which is in your favour as saloons go cheapest of all.

I too would be wary of this undertaking, you might be pleasantly surprised if you keep an eye on the usual sale sites as very low mileage 124 saloons come up every now and again.

I'm still running a 124 and following this years refurb work on it am hoping to run it for many more years yet, my E320 is converted to LPG and costs about the same to run as a modern clone Diesel hatchback.

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Thu 8 Aug 2013 12:14
Mercedes W124 - Gearbox swap from manual to auto - Mercedes W124 Indian imports

The engine is the 220 (presmably the 150 BHP engine).

I think you have probably advised enough potential problems for me to give the idea a wide birth. The car in question apparently has an MOT, and is calibrated in Kilometers which seems to be acceptable for the UK MOT test, and the lighting also must be compliant to UK MOT standards. The Indian import appealed as it is a newer vehicle and there none of the rust probs that are common over the wings, plus the a very good driver's seat where they wear on the side as drivers egress from the vehicle.

Thank you for your input.

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Thu 8 Aug 2013 17:28
Mercedes W124 - Gearbox swap from manual to auto - BenG

Much less hassle to look for a decent auto W124 for £3-4k and sell the old one. Check out w124.co.uk and mtsv.co.uk, among other specialists. The overwhelming majority of 124s are autos, so it shouldn't be too hard to find a good one for say £3-5k.

The 5-speed auto gives a higher top gear for motorway cruising with better economy, but is apparently less reliable than the 4-speeder and can be costly to fix.

The later, post-facelift cars (body-coloured front grille surround instead of all-chrome grille) are apparently less well built than the pre-facelift cars but have the advantage of more power and better fuel economy from the four valve per cylinder engines. The sixes (280 & 320) are known for problems with the wiring loom to the plugs and coil packs and also head gasket failures, which also affect the 220.

Edited by BenG on 08/08/2013 at 17:33

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Fri 9 Aug 2013 12:39
Mercedes W124 - Gearbox swap from manual to auto - Peter.N.

If I were you I would keep it manual, it will be better on fuel and cheaper to maintain and if you are about my age which your comments suggest you might be, a manual box is a lot safer, most accidents you read of involving elderly people are in auto's, with a manual you have to put it and your brain into gear before taking off.

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Sun 11 Aug 2013 09:56
Mercedes W124 - Gearbox swap from manual to auto - Mercedes W124 Indian imports

Thank you all for your input - I'll look at the W124.co.uk website and have and see what's available.

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