The MK3 Diesel Gearbox Thread

[dannyboy 0]

For all the people out there who would like squeeze bit more economy out of their corrado or prehaps want to use the torque of their engine a bit more efficiently without ruining the fun,the gearbox from a Mk3 Golf TDi is a welcome addition and upgrade.This Mod is suitable for all 4 cylinder raddos,but VRs have different bell housing i believe.

Many people report the diesel box is stronger but nobody can confirm this.Since diesel engines use lots of torque ,you'd expect VW to strengthen the box but nobody can say!

 

There are a varitey of boxes available and can come from different cars.As long as its a 02A box and not a syncro model box.Generally the passat,golf,vento and others in the 1.9 TDi range share the same 5 speed box.Other VAG cars will be similar but i cant confirm any vehicles that use them.The codes will differ as some will have different gearing.The two most common boxes are-the CTN and the ASD.These boxes are a direct bolt-on to 4 cylinder raddos except ones with 90mm drive flanges(very early models).The only problem that this mod has is the shifter tower is differrent on mk2 than mk3

 

The CTN box is by far the most popular upgrade.It has similar 1st,2nd,3rd gears as normal but with a longer 4th and 5th for motorway driving.These boxes will be more expensive than the ASD because of the this and one everyone goes for.

The ASD box has longer gears throughout and holds the longest gear ratio in fifth in the 02A box range making it brilliant for cruising on the motorway and saving fuel. But some find 1st gear a pain in traffic as its longer and more likely to stall if realese the clutch too quick.Its usually cheaper and for around £100 or less you can pick these up. This will pay for itself and more in the fuel return after a single year!

 

The only problem is the MK3 shifter tower is different than MK2 tower.

The left is mk2 and right is mk3

Left is mk2

The shifter is also shorter,so if you use mk2 one you wont be able to get 3rd,4th or 5th

internally different too.

Mk3 16mm

mk2 15mm

 

To get the gearcables to fit a Mk3 tower a very simple mod is needed.

On the MK3 shifter tower you will notice a black plastic joiner which acts to hold one lever to the tower and acts as a pivot point

This is removed by undoing the m8 bolt that secures it to the gearlever.Ive removed the shifter tower to make it easier to photograph.

Next mark plastic with small cut just where the webbing on the plastic stops rising

Then remove the bolt inside the plastic by gently tapping it out

Cut the top peice of the plastic top off so your left with this

Fit this peice back in the shifter tower

Now secure the plastic to insure it doesnt fall out with a cable tie or just stick it(cable tie is best as it can be removed again)

Place the cable tie at the bottom of the webbing so it wont go anywhere

Trim the excess off the cable tie and refit the shifter tower with a bit of sealant on the mating surface.Make sure you aline the little cup notch or it wont go in

 

Secure the tower down using the two m8 bolts and attach the gearcables.Remember to use the old mk2 attachment bolts and remember the square nut goes inbetween the change lever rather than under.

Be aware that that the old mk2 had adjustment for left-to-right plane only on the gearbox(forward-to-back was in the car).The mk3 has adjustment for foward-to-back adjustment too on the shift tower so it might take a bit of adjustment to get it right.Also youll notice its a bit tighter on the vertical linkage due to 8-10mm height difference but it wont effect the gear changes.

 

It TDi box will feel different as you have to work the box a bit more but you'll get used to it after a while and provided you drive normal 90% of the time you'll notice better MPG in a short while.

 

Obviously some people love having short gearing,it down to personal preference.But for those who'd like longer gearing invest in a TDi box is easiest way.Or just change fifth gear!

 

Dan

[dragon green 5]

Good write up Dannyboy,now he has got you hooked,read on

http://the-corrado.net/showthread.php?31273-best-gear-ratios-for-g60-gearbox&highlight=gear+ratios+G60

if that doesnt convince you,nothing will !

[dannyboy 0]

cheers man,spent ages writing and getting pics together.

[SIMONG 0]

nice one Dan, thanks for taking the time to do this as its gonna help me out loads as im sure it will help others out to at some point.

 

very good of you.

 

cheers Si.

[dannyboy 0]

no worries si,glad to help

[mikkijayne 0]

Why are you messing with shifter towers? Just swap the cables from the mk3 in to the Corrado shift box. Miles easier, and you can do a short shift while you're at it.

 

I would think performance in 5th is pretty dire with such high ratios unless you have a ton of horsepower.

[dannyboy 0]

Why are you messing with shifter towers? Just swap the cables from the mk3 in to the Corrado shift box. Miles easier, and you can do a short shift while you're at it.

 

I would think performance in 5th is pretty dire with such high ratios unless you have a ton of horsepower.

 

The whole point of this is that you dont need mk3 cables,you just do this 10 minute mod and your done,instead of dropping the exhaust just to get access to the gear shifter which is a pain.so how is swapping mk3 cables easier?

5th gear is a overdrive gear in these boxes,not designed for power.4th in asd box is like 5th in a ATA box.Some people use their corrado's as daily's so saving money on petrol makes prefect sense,petrol is not getting any cheaper is it?

 

A few people have fitted these to their G60s and valvers as these engines develop torque.Horsepower is to do with the top-end preformance which 99% of raddo drivers dont use all the time.This gearbox change mod is for people with more common sense rather than a big wallet!!

[SIMONG 0]

wahey! got my car back!

 

its been about 6 weeks but the guy sorting it has had a lot on and so have i so not been to rushed about getting it back.

 

engine sorted and runs great again. new poweder coated rad support panel on, poly bushed front cross member on and golf mk3 tdi gearbox now in to replace my busted 2nd gear/syncro

 

cant believe the difference, first and second are better than before but second now does around 70mph (which i tested but wont be doing all the time). 5th gear is also much improved by being a longer ratio. on the way to work today crusing at a comfortable 60-62mph rpm at 2k i managed to get 47.5mpg compared to what i used to get which was around 40-41mpg.

 

good to get her back!

 

cheers dan for the info on sorting this out.

[Purple Tom 0]

I've got a TDi 'box in my Corrado too - I'm bloody glad otherwise I don't think it'd do more than 60 ;)

 

I fitted a diesel 'box to the 1.6 Vauxhall engine that I put in my Mini too, mostly to make up for the difference in diameter of the Mini's 10" wheels versus the donor car's 15" wheels - I've always thought that a TDi box would be the way to massively improve economy. The Mini would cruise at 70mph doing just 2200rpm, resulting in almost 50mpg on the drive over to the Nurburgring. It'd also do 0-60 in 6.5 seconds and on to a maximum speed of about 130mph which was more than enough...all down to the ratios of that diesel gearbox.

 

Nice write up Dan :)

[Big Adam 0]

I've got a TDi 'box in my Corrado too - I'm bloody glad otherwise I don't think it'd do more than 60 ;)

 

I fitted a diesel 'box to the 1.6 Vauxhall engine that I put in my Mini too, mostly to make up for the difference in diameter of the Mini's 10" wheels versus the donor car's 15" wheels - I've always thought that a TDi box would be the way to massively improve economy. The Mini would cruise at 70mph doing just 2200rpm, resulting in almost 50mpg on the drive over to the Nurburgring. It'd also do 0-60 in 6.5 seconds and on to a maximum speed of about 130mph which was more than enough...all down to the ratios of that diesel gearbox.

 

Nice write up Dan :)

My brother is running vauxhaul engine in his mini but is only using the diesel 5th gear. its a bit odd as you rev the nuts off it in 4th then pop it into 5th its about 2000rpm at about 70! did you run a complete diesel gearbox or just the 5th gear?

 

anyway i think diesel box will be going in mine over the winter. cheers dan :)

[Tristan H 10]

can you just change 5th , in your original box?

[dannyboy 0]

can you just change 5th , in your original box?

 

Yes you can, and its even possible to do it while the box is on the car(difficult though)but you'll need gear-puller and doing this first time your very likely to damage the teeth on the gear ring so it may not out-weigh the problems of just fitting a box as opposed to running the risk on damaging the teeth trying to remove fifth gear. If you have mechanical knowledge and correct tools you can try the fifth gear but you still have to source the the two gears needed.

 

Ive got 1,300km drive back to ireland(meath) for christmas,do what i usually do at christmas.... :drinking:

 

Thanks for comments guys,feel more that people help each other,the better the forum gets!!!

[Tristan H 10]

cheers for that , might drop on a Vento box so , I promised I wouldn't modify this one (too much).....