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Fitting a taller 4th gear to a 1.9DG gearbox
Posted: 07 Mar 2010, 12:08
by jonnyg
as the title says really, im after a taller 4th so i can cruise a bit better.... anyone know the procedure? Im hoping its a simple thing, end plate off e.t.c.
Im geting fed up of screaming at 70mph...
cheers
Re: Fitting a taller 4th gear to a 1.9DG gearbox
Posted: 07 Mar 2010, 13:15
by CovKid
Its not simple (or cheap) but is dooable. I raised this with Aidan and to be honest its better done as part of a box rebuild and expect the gear itself to be in excess of £300 - before even costing the rebuild. Fit bigger wheels?
Re: Fitting a taller 4th gear to a 1.9DG gearbox
Posted: 07 Mar 2010, 13:54
by Ian Hulley
You're thinking of the fwd T4 gearbox where a longer gear can be fitted in an hour and a half. To dismantle a T25 box isn't an easy proceedure that mere mortals like us should consider.
Now Aidan on the other hand .......
Ian
Re: Fitting a taller 4th gear to a 1.9DG gearbox
Posted: 07 Mar 2010, 14:47
by phester
why dont you just put in a 5 speed dogleg box cant be too hard to find 1
http://shop.ebay.co.uk/?_from=R40&_trks ... Categories" onclick="window.open(this.href);return false;
Re: Fitting a taller 4th gear to a 1.9DG gearbox
Posted: 07 Mar 2010, 15:13
by kevtherev
phester wrote:why dont you just put in a 5 speed dogleg box
because it wouldn't give him the taller gear in 5th as it practically the same as his 4th now
Re: Fitting a taller 4th gear to a 1.9DG gearbox
Posted: 07 Mar 2010, 15:39
by CovKid
Bigger wheels help a bit. For some reason no one has been able to fathom, the suspension on mine is really high and 14" wheels made it look like it was fitted with mini wheels so I fitted 15" steel merc wheels and it'll actually do 90 flat out now (go figure). Theres still bags of room in there - could easily have got 16" wheels on. Its a thought anyway....
Mines a 5 speed and it definately doesn't scream its guts out on a motorway. Probably save a little fuel too I suppose.
Re: Fitting a taller 4th gear to a 1.9DG gearbox
Posted: 07 Mar 2010, 15:42
by billy739
you need to know the code on your box so you kno whats better!
lots of boxes/ratios as standard but also a selection of upgrades depending on budget.
dk Aircooled 2.0 box is the only easy straight swap( gear selecter bar needs changing and modifying ) along with the front mount needs modding.
top ratio is the same as the 2.1 5 speed AAP code.which has the tallest top gear of the standard water cooled boxes
there are plenty of gear ratio programmes on the net so you can calculate your engine speed against road speed once you know your box code.
AAP standard box give 3400 rpm at 70mph from memory , i have got mine down to 2900rpm using a different 5th gear on the AAP box and using larger tyres