Club 80-90 Forums

Hi All,

Ok so this might have been spoken about before, but I'm yet to find a thread that goes into detail about other options. Apologies if this has been talked about in depth before.

I'll cut a long story short. I've been putting a 1.8t in my T25 with a flipped gearbox from a Porsche 986. Same transaxle as the Passat B5 and A4.

This has not good as well as I wanted it to. I've mounted the engine at 50 degrees. If I knew how much trouble it actually was going to be then I'd have gone with 20 degrees. Partly the reason I've started this thread up is that I am going to undo most of my work and go for 20 degrees, however I don't like how low the engine sits with the flipped box, even at 50 degrees the sump is way too close to the ground. It is actually a lot lower than I originally realised. I also have a bit of a space issue on the left side of the engine where the turbo is. Basically there is hardly any space there now and everything is proper tight. I thought I was coming to the end of the project as it was just wiring it all up and it does actually run now with all the wiring outside of the vehicle. I thought doing this at 50 degrees would be the best option but it's not really had that much of an advantage. In hindsight I'd have gone with a 20 degree install and not bothered with all of the other messing about such as changing the sump, oil return for turbo etc. Anyway, enough about that and let's get to the point.

the big question is "What would be a good alternative gearbox to use that wouldn't require it to be flipped 180 degrees?"

In an "ideal" world it would be great if someone could make me a pinion and crown wheel for the Passat gearbox that would reverse the rotation instead of having to flip the box, because that is actually quite annoying. The only thing with that is I'd have to transfer all of the gears off the existing shaft on to a new one. If the Passat/A4/Porsche box could sit the right way up but with rotation reversed inside the box then that would be a pretty decent winner. It's going to be expensive though to get someone to make this happen, unless someone knows if someone has actually done this before or if someone would be willing to do this without me having to re-mortgage my house to fund it lol.

So, I want to know what other gearboxes could be used before I go and buy another adapter plate from Ultimate Engineering and get another bellhousing machined for 20 degrees.

If there is a better alternative out there than turning a gearbox upside down then I'd be really interested to know everyone's thoughts on it before I go any further. Using a standard T25 gearbox is totally out of the question. I really dislike them and was mostly the reason to do this conversion in the first place. I am sure they were great 40 years ago.

I know people use the Renault transaxle boxes. The UN1 seems to be a good choice, but I find them quite rare and also expensive when they do eventually surface! I'm also not sure how well one would mate to the 1.8T. I guess the easiest way would be to buy the ultimate engineering adapter plate that allows the VW T25 bellhousing to fit on it. In my case it would have to be a diesel one to make it fit the 1.8t engine. I also hear that flipping the diff is quite straight forward.

Subaru box might also be an option. Not sure how easy it is to reverse the rotation on that, or if it will even mate to the 1.8T easily.

What other options are there?

Looking forward to hearing everyone's thoughts before I progress any further with making a decision on what I'm going to do next.

JC

Have a search for a company called “Subarugears” for a reversed conversion to a Subaru gearbox.
I don’t think it is possible with the Audi/Passat ‘box.

I have a Renault UN1 available. New pinion bearing and part rebuilt with several synchros replaced (some needle races nla) but really needs a LSD to make its full potential as the 2 pin diff is tired (a known failing on an otherwise very strong transmissionl)
3.78 diff so needs a torquey engine but will allow low revs in 5th. Ideal for a TDI
WBX/Porsche 4 stud custom short billet bell housing, will need an adaptor plate and flywheel but there is a new 228mm HD clutch cover good for 350lb/ft

silverbullet wrote: ↑26 Nov 2022, 13:47 I have a Renault UN1 available. New pinion bearing and part rebuilt with several synchros replaced (some needle races nla) but really needs a LSD to make its full potential as the 2 pin diff is tired (a known failing on an otherwise very strong transmissionl)
3.78 diff so needs a torquey engine but will allow low revs in 5th. Ideal for a TDI
WBX/Porsche 4 stud custom short billet bell housing, will need an adaptor plate and flywheel but there is a new 228mm HD clutch cover good for 350lb/ft

Hello Silverbullet,

What are you selling this transmission for? I'm not sure how easy it will be to get it to mate to my APU or APX engine I have. I recently aquired an Audi TT 225 with the APX engine that I'm going to put in now. 

I haven't put a price on it yet as it is dismantled, no point reassembling it with a worn diff. A new LSD for a UN1 will set you back around £1200, so thats a guide as to its potential full value.
How much would a full house rebuilt HD 4.14 VW transaxle with LSD cost?
I would investigate the adaptor kits available to convert a wbx bellhousing to inline and go from there.

silverbullet wrote: ↑28 Nov 2022, 13:38 I haven't put a price on it yet as it is dismantled, no point reassembling it with a worn diff. A new LSD for a UN1 will set you back around £1200, so thats a guide as to its potential full value.
How much would a full house rebuilt HD 4.14 VW transaxle with LSD cost?
I would investigate the adaptor kits available to convert a wbx bellhousing to inline and go from there.

To be honest, I think I will machine my spare 012 bell hosing for a 20 degree install with my 1.8T and see how that goes. I just dislike how low the engine has to be to make it work nicely. 

Porsche 993 or 996 box is an option, they are practically the only other rear engine rwd vehicle out there. They used to be pretty readily available and not that expensive as they are always crashing them and they are plentiful and not really classics so get written off and broken; I know a few people have gone down that route.
One of the old passat auto/triptronic boxes can be reversed by adding a reversing gear set on the front of the box, there was a guy in Italy/Germany who did that back in 2011/12, he called in here and showed me pictures of it all and explained it to me, but I lost his contact details following a PC failure unfortunately; there will be info out there but finding it now may be impossible, so many websites have gone and even if they have been archived with waybackmachine or the like unless you know what you are looking for it can be hard work. IG16 was lost completely in a server failure and that was a brilliant resource for Syncro especially.