6 speed gearbox

[Gordon Ward]

My 97 1.9 Z3 does a fair bit of motorway mileage but at 70mph/3000rpm it is clear that an extra cog would be nice. Has anyone fitted a 6 speed gearbox? If so, what vehicle did it come from, how much did it cost and most importantly, was it worth it?

 

[billz]

I know someone has done it but cant remember who it was. It may of been a member who passed away called JR. @GazHyde will probably remember who it was

 

[Dino D]

I know it has been done on on the US //M version using old 5 series parts and a small bit of fabrication.
Space is not an issue. BMW's were telling porkies when they said the 6spd couldn't fit in the Z transmission tunnel.

 

[GazHyde]

Often discussed, but I've not come across anyone who's attempted it. Considered it for my 2.2, but then I bought a 3.0si Z4 which fixed the issue as that has 6 gears!

Wonder if @windym has been thinking of gearbox upgrades on his 1.9 project car?

 

[oldcarman]

I remember discussing this with Zedonist when he had his single weighted clutch and flywheel set up done but it didn't get much more than that. This is something that i believe can be achieved with a simple adapter between the motor and transmission. I intend to talk to my street/hot rod buddies who have done many adapters disigned to mate Chevrolet to Ford or Chrysler transmissions. Would love to hear if any one has any other ideas!! JIM

 

[Brian H]

This is quite a popular modification in the states, I have heard of a few cars in the UK that have been converted but I have never seen a shopping list of parts.

My understanding is that it is mainly OEM parts off other BMs but you need to get the prop shaft cut, welded and balanced to the correct length.

 

[madleemark]

if you google it, theres a good read on Eat sleep tinker, putting an e46 6 speed into an e36 coupe, gives you some idea off the work needed to do the conversion, it would be a worthwhile mod, i to have to use the motorway every day and another gear an overdrive for lower revs at speed would be good

 

[the Nefyn cat]

Hoping to do this myself, just a matter of getting the back axle in after changing pretty much everything. It may not really be worth the hassle, but quite like a challenge. If only work didn't keep getting in the way. And converting my place into a house. And playing with my horse. And all the other time-wasting stuff. So where do I find a "not enough time in the day" emoji thing?

 

[oldcarman]

@ the Nefyn cat just don't be under the illusion that retirement will help you out with that!! It's false thought unfortunately!! Would like to hear how you make out though, cutting and balancing the drive a shaft won't be a problem for me, i've lots of hot rod buddies have done it hundreds of times as that's one of the things needed be done when installing motor x into model y!! I don't know much about BMW's to be honest so rely on the expertise of you forum members!! lol. JIM

 

[Poprin]

Is this idea for fuel economy or noise?

Because you could buy a lot of fuel for the cost of doing a transmission upgrade. Also I found my M44 to be great on fuel on a run (or just tatting round town!) and I can't imagine that dropping the RPM by 500-1000rpm is really going to make a measurable difference. Also I think that the oem getrag box in the M44 is sweet and the gearing is fantastically balanced for acceleration.

Also when you've got some Audi LED's in your rear view mirror you don't have to drop a gear to show them who's boss

 

[oldcarman]

Absolutely @ Poprin you can buy a lot of fuel for the cost but a sixth gear would allow you to run the engine in its sweet spot and gain mileage. Motor will appreciate the lower cruising RPM's and last that much longer. Dependant of Course on the gearing ratio of the trans. I do 99% of my driving at highway speeds so the gain would be worth the pain!! JMHO. JIM

 

[the Nefyn cat]

I'm not really hoping for massive gains in economy or cruising-ness, more just to see if it's possible (and for the sheer joy of having something that no one else has got) I've seen plenty of write-ups about doing it to Z3Ms, but not to the smaller engined ones. Still,first get the back axle back in.

 

[oldcarman]

Should have added to my last post "but I do like to get to hiway speed as quick as the next guy or quicker"" lol JIM

 

[Chris Hunter]

Interested in changing my 5 speed for a 6. can anyone advise on which six speed box is best suited, or do Z4s all have the same box.
many thanks
Chris