5 Speed Gearbox for a 460 280 Petrol Wanted

Hi - I am looking at changing the 4 speed manual on my G Wagen 1985 460 280 Petrol to a Getrag 5 Speed.  I have little or know knowledge of such things but hope it will go straight in and improve my MPG to something I can live with.

Any advice will be appreciated particularly on any mods required to do this swop.  Or is there a better gearbox readily available to do the same thing without too many mods??

 

Cheers Everyone
 

Time remaining: 5%
10/05/2021 (2 days)

Comments

mgrays's picture

Re: 5 Speed Gearbox for a 460 280 Petrol Wanted

I would not waste your time. The Getrag is weak IMHO, The 4 speed you have is the Mercedes "steel Van gearbox" and you can get it in 5 speed versions. Trouble is you will need to change the propshaft between gearbox and transfer box as the 5 speeds will be longer.. so might as well do it with the stronger Van gearbox. The Getrag has a nicer shift (wife does not like the Van gearbox shift but I still need to lengthen the Cosworth gearstick) but is prone to jamming in gear if you are heavy handed... and in my case lost enough oil from the gear selectors seals to destroy the weak input shaft needle bearings. I have documented how to do the 5 speed van gearbox on here. As for economics .. it will not pay you back in fuel; you would be better off exploring bigger tyre diameter to increase the gearing but this will be at the expense of braking power.

Jdring's picture

Re: 5 Speed Gearbox for a 460 280 Petrol Wanted

And there is the answer.  A grand for the gearbox and your time fitting.  And the risk that it is not a dud.

1k in fuel gets you 2,500 miles (@15mpg).  If the 5th gear improves mpg by 3mpg, you get 20% more (500miles).

In short, it won't be worth it.  You won't recoup the investment, but you will have the satisfaction of doing it and a better drive (if the box is good!).  Take your existing G and make that better, and live with the fuel.  Buy a run-around if you need to commute and keep the G for worthwhile trips.  Just my 2 cents.

johnhogg441@gmail.com's picture

Re: 5 Speed Gearbox for a 460 280 Petrol Wanted

Dear Jdring  Thank you for your response - you are correct the swop would not recoup the cost in better fuel economy. Perhaps if I increased the size of the tyres might give me a bit more.  I also thought of an LPG setup.  My experience opf LPG was with my Vito van - which I seem to remember was only doing about 5 miles per ltr.  With that sort of miles per litre and given the half price of gas it would stil give me a little increase in afordability. 

I also though of the rear diff ratio - but my knowledge of these things in limited - do you have any advice along these lines?

Thanks again

 

John

mike's picture

Re: 5 Speed Gearbox for a 460 280 Petrol Wanted

i have the 717.4  spd transmission available. Its was taken apart inorder to rebuild it. I ordred a lot of new interanl aprts for it. It just need to be reassembled. let me know if your interested in it? Thx

johnhogg441@gmail.com's picture

Re: 5 Speed Gearbox for a 460 280 Petrol Wanted

Hi Mike - Thank you for responding - I might be interested but I'm not sure whether I would be up to re-assembling the gear box - would you do this for me and if so at what price would the whole be?

I am in Tadcaster - where are you??

Do you know if this is a straight swop for the 4 speed I have in at present?

Cheers

 

John