Hello,
The W123/W126 used a 717.400 five speed with seperate bellhousing(5th.gear ratio 0.813). No Getrags on MBs !
Have a good week.

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Nachi11744

Hi what 5 speed tranny will fit/mate to a M115 petrol engine 2277cc 85 horses (2.3cc) without prop or mount mods basically a straight fit, this is based on a 207 T1 model (1978 hymer B504 with a 4 speed, possibly one of the oldest MercB Hymers in the UK) or is their an overdrive unit that could fit on.. or is worth fitting a diesel and box straight in... the petrol engine is a good engine with only 77000 miles on, but lacks guts on inclines.

Regards Gary

The five speeds with 1:1 ratio on the fifth gear were used in vans. The first gear was a very short take-off gear.

In the 1970s in the passenger cars ZF overdrive five speeds were used, with a 0.875 ratio on the fifth gear. When a five speed was installed, the final drive ratio was made shorter, so the overdrive effect was marginal.

When the W123 was introduced, the five speed was dropped, only to appear again late 1981. Those were Getrag five speeds, with a 0.81 ratio on the fifth gear. The final drive ratio was the same for four or five speeds, so there was a large overdrive effect.

Going to a 5 speed won't help the lack of power on inclines. 1 to 1 is 1 to 1 no matter how many shifts it takes to get there. An over drive will make the problem worse.

A 5 speed is only beneficial to higher revving engines and to help with your mid-ranges.

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“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
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Some numbers on the gear differences for 4 vs 5 speed. W114-W115-280C2-Getriebe/en

Thanks for your reply.. It may be beneficial then for me to convert from petrol to diesel, after all Im after better MPG with a bit more grunt..
So what engine and box would fit straight in without prop mods? It currently got the M115 2277cc 85bhp does about 15mpg based on a early 207 T1 Transporter? I was considering a 5cyl 300d? but not sure what would fit.. or is it worth staying as a petrol engined vehicle?

Which car do you have, please?

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I have a ZF 5 speed in my '66 230SL 2.5 and it works nicely. Third speed syncro is a bit weak so I have to be careful while shifting.

ZF is making this gear box again but seems to be hindered by production problems. I understand that they were taking orders and were looking at 250 units. Spare parts will be available again once the orders are filled.

ZF is very slow to respond to questions, if they respond at all, so you may find talking to them to be very frustrating. I believe the new box is somewhere in the 7,500 euro range.

The ZF box used on 113's had the 4.08 rear axle as standard which made 1st gear so low that it was almost useless. I changed my car over to a 3.92 LSD which is just about right. I'm getting somewhere in the 9 -10 liters per 100km range with this set up. This is about 23 - 24 miles per US gallons.