Any problems using a 1.8 gearbox in a 1.6 GTI?

In the process of restoration on my 1.6 GTI.

I've been having troubles with second gear releasing. Before the gearbox guys start diagnosis, I've come across a 1.8 gearbox for £200.

Is it worth picking up? Will there be any problems installing the 1.8 gearbox on a 1.6?

I know how expensive these gearbox scenarios can be so that's the reason I'm prepping for a potential replacement.

Thanks for your help.

It depends on the details - there's many different kinds of "1.8" box, including those from the Mk2 Golf/Jetta etc too, and with 100mm driveshafts (the 1.6 would have been 90mm). Also there's fitment differences although I think the Mk2 stuff is a superset of the Mk1 fitting holes so you can work it out. And reverse light wiring if it has the different connector (still resolvable if you know which connections to make though).

I did a guide on it, I'm not sure if its still on the website somewhere.

paul_c said

It depends on the details - there's many different kinds of "1.8" box, including those from the Mk2 Golf/Jetta etc too, and with 100mm driveshafts (the 1.6 would have been 90mm). Also there's fitment differences although I think the Mk2 stuff is a superset of the Mk1 fitting holes so you can work it out. And reverse light wiring if it has the different connector (still resolvable if you know which connections to make though).

I did a guide on it, I'm not sure if its still on the website somewhere.

Not sure why this topic posted twice. I'm also unsure how to delete the other.

Sorry, I should have been more specific. The 1.8 box for sale is from a Mk1.

I'll try and find the guide for more info also, thanks.

If you know the Tranny code you can use this chart:
Transmission Ratios

If you have 90mm axles just swap the cups over all it will cost is a couple of seals, that is if the donor is 100mm axles and this late in life you never know what others have done.

If you have 90mm axles on your ride, then the newer tranny has 100, you would also need the spindles off of a donor with 100mm axles to swap, that is why you need to change the cups only on the differential, and you don't run in to a gammit of other issues.

I swapped 90mm axles in to my 100mm cupped dead cabby tranny and gave me a spare set of 100mm axles for my other Cabriolet, and all I had to do was to change the cups.  So I am driving my 93 Auto with 90mm axles.

just to add, early 90mm cups wont fit a later type box with 100mm shafts. you'll need later type 90mm cups from mk2 1.6 or mk3 n/a diesel