5 speed

[Taleb]

hi experts ,

i have 4 speed 280sl pagoda and I'm planning to fix 5 speed transmission , will that reduce the RPM without modifying another part such as rear axel ratio .

[mdsalemi]

Yes, if the 5th gear is overdrive it certainly will.

AlexD fitted a 5-speed, and so did Raymond, two long time members here. Different transmissions I believe. Nothing is easy, so be prepared for some work they don't tell you about.

[lagolag]

I have the Getrag 265/5 5 speed installed in my 230SL and the Fifth has 0.8 ratio, its a huge difference. I bought a used gearbox and the installation parts from Wolfgang in Germany and drove it last season, unfortunately the gearbox was in worse condiction then expected so I had it rebuilt in the beginninging in 2025 and now its installed again and it is like new car.
My gearbox was rebuilt Hulleman classic gear in NL, grate job well documented.

[mdsalemi]

…unfortunately the gearbox was in worse condiction then expected so I had it rebuilt in the beginninging…

When my car was restored in 1999–2001, I made the mistake of having the transmission put back without any knowledge of its condition. It was slipping and needed a rebuild. While an automatic, “take the point”; if you have the tranny out—any tranny—ensure that what you replace is in excellent condition…

…unless you enjoy taking transmissions out or paying someone to do it.

If in doubt: rebuild it. You won’t be sorry, you cannot be sorry when a rebuilt part is installed. But when you go through the effort of swapping any part and then find out that it’s not working properly… that is when you’ll be sorry.

[Jack the Knife]

I have the Getrag 265/5 5 speed installed in my 230SL and the Fifth has 0.8 ratio, its a huge difference. I bought a used gearbox and the installation parts from Wolfgang in Germany and drove it last season, unfortunately the gearbox was in worse condiction then expected so I had it rebuilt in the beginninging in 2025 and now its installed again and it is like new car.
My gearbox was rebuilt Hulleman classic gear in NL, grate job well documented.

Just FYI for those at home -- 265/5 is the racing gearbox (close ratio, no OD 5th) which has very slightly different dimensions to the 265/6, which is the one with the OD 5th and what is in your car. I tried to fit the 265/5 into my car and was not successful, and opted for a 265/6 instead. Seconding Wolfgang as the source, but I have bought two kits from him and his packaging job needs work.

[zoegrlh]

Changing the rear end will make a difference too.

[mda]

I am also considering replacing the gearbox with 280 sl. Should the marking on the gearbox be Getrag 262.0.510.00?

[lagolag]

mda,
I suggest you to use the forum, do a search for Getrag on the entire forum and you get all the answers you need, that's the way I did at the time when I decided to go for the 265/6.