4 speed or five speed gearbox

[wiggy]

would there be a big difference on fuel between 4 speed or 5 speed running the van at the moment with four gears as fifth gear is knackered but got a 4speed to put in

[MidLifeCrisis]

Very broadly speaking 4th gear in a 4-speed box will be similar to 5th in a 5-speed box - so yes, you'd be better off using a good 4-speed box rather than a 5-speed box without 5th.
If you know the codes of the gearboxes you can compare the gear ratios of the two boxes here;
http://www.brick-yard.co.uk/VehicleSpec ... fo/gbx.htm

However, I think you'll also need to change out the gear shifter mechanism if you're changing from a 5-speed to a 4-speed........so it's not as easy as just changing out the box.

[wiggy]

cheers thanks for the reply I see we run the same engine a df with some dg bits I have an 89 van with a 84 engine

[MidLifeCrisis]

cheers thanks for the reply I see we run the same engine a df with some dg bits I have an 89 van with a 84 engine

Mines an '84 van, used to have a DG, now seems to have a DF with various DG bits strapped to it ....... bit of a Franken-engine?!?!
Also until recently the petrol engine had a diesel gearbox strapped to it ....... it's amazing what happens to these vans over the 30 years!!

[CovKid]

Again, just to dispel the myth that a 5-speed is somewhow better than a 4-speed, I have a 5 speed gear box and basically the only difference is in the 1st-2nd range (sad but true). Most who have 5-speed boxes tend to pull away in 2nd most of the time as 1st really IS a crawler gear. The 5th gear is comparable to 4th on four-speed boxes - more or less. Nowt to be gained by swapping in my view. You can get a far better and more noticeable improvement in terms of gearing by just increasing the wheel/tyre size a little.

The subject tends to come up because you get the sense that if there was 'one more gear' after 4th, you could cruise effortlessly. That doesn't really pan out. Its been discussed no end of times, but it is possible to change cogs in a gearbox to make them longer but its damned expensive and you soon start hitting the limitations of the engine itself.

I found the 5-speed box very frustrating to be honest and it really only became useable when I went up to 15" steels, at which point the speedo was right and the gearing began to work a little better but 1st is still practically useless other than when pulling away on a very steep gradient. Even then, you're into 2nd within a knats whisker which means a lot of nifty if not annoying gearstick work (don't forget its a dogleg at that).

The other flip-side (although this may be true of 4-speed - I don't know), there are certain speeds on the 5-speed box (often when I'm sat behind Nissan Micros oddly) when the revs are all wrong and going down or up a gear doesn't help. It becomes really tedious. Mind you, this seemed to be true of the VW Bug with a 1600 engine when sat behind an Austin Metro, so maybe its common to all.

Just my observations from a practical rather than mathematical viewpoint

So, if you've got a 4-speed and for some reason hanker after a 5, forget it. Save your pennies and invest in 15" wheels where tyre prices tend to be more competitive anyway.

[discipleofsketch]

Also, just to throw this in and muddy the water even more - i'm running a 5 speed box on a 4 speed lever and linkage, to get to first I have to depress the lever to get it to move left through the gate in the same way as you do for reverse. Not sure if this means you can also run a 4 speed box on a 5 speed linkage?

I would change over to a 5 speed lever etc., but my long term plan is to have the 4-speed rebuilt and put that back in anyway.

[discipleofsketch]

Again, just to dispel the myth that a 5-speed is somewhow better than a 4-speed, I have a 5 speed gear box and basically the only difference is in the 1st-2nd range (sad but true). Most who have 5-speed boxes tend to pull away in 2nd most of the time as 1st really IS a crawler gear. The 5th gear is comparable to 4th on four-speed boxes - more or less. Nowt to be gained by swapping in my view. You can get a far better and more noticeable improvement in terms of gearing by just increasing the wheel/tyre size a little.

The only reason I swapped form a 4 to a 5 was to swap from a diesel to a taller-geared petrol box - I would have gone for a petrol 4-speed if one was available (in fact the previous owner of the petrol box thought it WAS a 4-speed, and had been driving it as such )

On my tdi conversion, pulling away in 2nd is actually very sluggish until the turbo kicks in, it feels laboured, so I only do it when i'm already rolling a bit or downhill, the rest of the time I have to put it in the horrible dog-leg first (and then it wants to pull wheelies if I put my foot down).

[wiggy]

that's it settled then take out the knackered five speed and put in the four speed box and leave it like that

[CovKid]

4-speeds are also plentiful and don't cost anywhere near as much as 5-speeds. Once mine goes, I'll be putting in a 4, plus change mechanism..

[ajsimmo]

Also no need to change gear lever if you don't want to. 5sp lever will work with the 4sp box - just remember not to go for the old 1st gear!

[CovKid]

Useful to know. I suppose it wouldn't be too difficult to fit a 'no go' bracket into change box to stop that either.