So i've been thinking .... about a Boxster transmission in my car ...

I've made a little more progress on it, I just need to figure out where I want to mount the starter. I'm going to model up the stock location and see how that looks.

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Very cool

I was told by a trusted source one could also cut and modify the bellhousing to make it fit.

....cutting....
I'm toying with that idea as well.

One plus I see with cutting is that it makes for a shorter flywheel from some quick drawings and thoughts about it. It does change the angle of the axles a bit.

Making sure the newly cut surface is acceptably perpendicular with the output shaft is a concern.

I'm trying to avoid gutting the transmission in order to move it or set it up easier for modification.

Top view with axles aligned together (close enough)

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Top view showing size comparison

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Side view, input shafts aligned, cannot see Boxster input shaft due to it being setback into bell housing approx. .50"

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Top view showing axles when input shaft tips are aligned or even side to side.

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Type IV flywheel with clutch and pressure plate inside of 901 transmission.
(note input shaft location in flywheel) 215mm pressure plate

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Audi 1.8T/V6 228mm flywheel, pressure plate and clutch in Boxster transmission
(can be upgraded to 240mm via many resources)

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Type IV flywheel inside of Boxster transmission.

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Andyrew, have you taken apart a box yet? I'm thinking that I might do some welding to the box if I continue to move forward.

Bump for Clay, not sure if how much different the 6 speed box is from the 5 speed Boxster box?

I have both and the bolt patterns are the same. What else you need? Right now it's out of the car waiting for me to ship it to Dr. Evil. Needs a bearing in the cone...

Although there are other Boxster 6 speeds with a round, more traditional bolt pattern.

Ive got a spare 5spd quattro box I have been debating welding up like the subaru guys just to see if it works. Just to see if it would work for the 6spd audi trans. Do you want it for experimentation mike?

I have never opened a box but I have all the manuals with the diagrams.

Please make a bolt on solution, not a machined setup that requires taking the bell housing to some shop.....unless you sell it like that.

Rich

The Boxster 6-speed stock clutch and pressure plate can be bolted directly to a 964/993 flywheel with no mods.

An aluminum adapter plate can be made to bolt the boxster trans to the 911 engine.

The 944 turbo CV joints bolt to the Boxster output flanges.


The problem becomes the starter. I am working on how to fix that.

Part of the advantages of running Boxster S transmission is the cables/shifter all work
Perfect together.The bonus is extra gear 6 Speed.......

Actually, the advantage is a large R&P - the weak spot for the 5 speeds. The 5 & 6 speeds are two totally different animals from a durability stand point.

Tony

Never thought about braking the trans...I'm putting 350ish hp through mine and have had no trouble.
Price was right,paid 750 for my 2000 with 100k on it.Got the stock cable's and shifter too.

Ebay

This thread isn't about alternative transmissions behind a T4 engine anymore, is it?

A local shop that builds Boxster (BSR) race cars, said the 5 speeds are junk and they go through quite a few of them. They said the Boxster 6 speed is much stronger.

It was...a Subaru transmission still might be a more "practical" solution, but this is the path I am going now until I change course and direction which is fairly typical of me

i was wondering this too. at some point a V8 was mentioned

Mike, if you want to borrow my 6 speed for mock up, I would be willing. As long as you don't cut it up.

WOW this thread rattled some cages!!

So the vw axles are hollow, yes the subaru axles can be resplined. But what are you trying to fix by changing trans to a later version? Suby / suby I get it's a no brainer. Audi/vw / vw I get. Aircooled/ Audi or suby? Not sure if the extra work would be worth it.

Jcl

...I saw this question and then a statement from 1stworks regarding the 6-speed (and just responded to those). I never even saw the original post/question for the thread - just the other's follow-up posts. Sorry if the relevant information didn't come from a different member. LOL.

T

I appreciate the information. I doubt I'll ever "need" the additional strength of the 6 speed over the 5 speed version, however if it is better transmission overall due to design it might be worth considering if someone else was doing the conversion.

thanks Mike, I'm so far off time wise on this project that I'm sure you'll have the box back in the car by the time I get around to it!

I am also curious if the gearing from the Boxster/Subaru will be to high for a type 4.
I went with a 915 gearbox for my 3.2 because the 914 trans was geared to low. This was 10 years ago before the adapters started showing up for Subaru and Boxster trans options.

Ive have drivin and help build both.The suby H6 and 2.5 with suby 5 speed.
Both where a pleasure to drive but the Boxster S 6 speed way better way to go.
Better gearing and way better shifting.

I run 205 50 15 on my boxster S 6 speed.3000 rpm's @ 68mph.
Iv never run it out in 6th,way to fast for me...well over 130.
1st gear very usable.

I would have been tickled with a built T4 and boxster S 6 speed combo.
They just drive and shift so nice

Lol

Absolutely nothing wrong with threads that ricochet around, a lot of times they're the most interesting.

The thing I haven't understood is doing all that work but keeping the T4. No need to concern yourself about transmission or axle strength with that motor, so it's just to get better shifting? So I'm curious, but will wait patiently to see how it all turns out.

'cause I already spent $500 for a silly supposedly rebuilt 1.7...

O.K., but going through all that work to adapt a modern transmission to the silly 1.7? Aren't you kind of painting yourself into an aircooled corner? Wouldn't it be better, both long and short term, to sell that engine for $500 and start with a clean canvas? Maybe a $500 bolt-up Passat engine with twice the power, for not a lot more work?

Either way will be fun to watch.

Stop being logical...hahaha

Logic does not equal fun for some of us....

I don't know... It's been sitting in my garage for 6 months waiting for me to ship it to Ohio... I know the good Dr. has plenty to do whether I send it or not. I guess I'm lazy and it's a PITA to ship. Awkward and heavy.

This is a pic of the other type of 6 speed (not mine). Look at the starter location. This might be a better option for machining a rear starter solution...

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Ok, so i need a Boxster 6-speed with assorted shifting hardware and some sort of adapter to mate it to the 3.6L and i'll be all set?

Mounting ideas.






Just for quick laugh v8 flywheel to boxster S 6 speed

Wow. That's a lot of very fine metal.

The problem is not hooking up the boxster trans to the 964/993 motor. The problme is finding a place to put the starter. A V-8 starter mounts to the engine, so no starter on the Boxster trans is no problem.


I have a plan in mind, but I don't want to say anything until I actually do it.

Can someone measure the OD of the flywheel and the ID of the trans where it fits? Thanks

A few merge drawings.

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What side is the inlet for the hydraulic throw out bearing ? On the 5 speed it is on the drivers side. That box does look a lot easier to adapt!

Mike,
What is the ID of the bell housings on both a G50 and the Boxster 6 speed?

Clay

1 of 2 Mikes in this thread

Porsche 914/G50 = 276mm or 10.86"

Boxster 01E = 293mm or 11.54"

I'd say accurate to .02" or so
(added .80" to compensate for the thickness of the jaws )

Maybe Mike can measure his 6 speed?



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Drivers side

Killer renderings Mike

Mr. Mueller is out and "engineering again"!! The world is not safe from the "engineering hands" of Mr. Mueller!!! LOL! LOL!

Great to see you back into the different project development ideas and project possibilities involving our cars. Keep the good thoughts coming.

Steve

As per Mueller norm..." a solution looking for a problem" hahaha

In fact, I'm thinking about a Boxster tranny mated to a more powerful engine, like a six, instead of my lame 1.7. And with that upgrade, I would need to come up with stronger suspension, brakes, wider wheels. Bigger engine also gives me more possibilities around heaters and AC, if I go with a water cooled engine.

At some point, should I just consider a complete mid-engine Porsche car upgrade? The Boxster tranny upgrade, coupled with the rest of the Boxster, also gives me the advantages of a modern vehicle (airbags, structure, etc) in case I get in an accident. In fact the only downside to a complete Boxster upgrade is I lose the coolness factor of driving a 1970s era Porsche 914.

I guess what I really need is a 1972 914 body kit for a 1999 Boxster. Kinda like making a 1950s Porsche Speedster kit car from a modern chassis. Anything out there for me?

Before my Boxster S 6 speed and LS conversion plate go to their new homes I thought I'd take a few pictures. I wonder how far along Clay is with his adapter plate? I'm sure a lot further than I am.


Plate bolted to Boxster 6 speed:
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Bolt patterns on Boxster/Passat 5 speed that match the Boxster 6 speed, notice the extra unused holes, that for bolting up different Audi/VW engines that have a different bolt pattern.
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Plate up against Type IV engine.
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I have the first actual aluminum plate sitting on the table in my laundry room (gotta love a wife that loves 914s). It is partially drilled, but we are not quite sure if the holes are going to line up. So I am going to test fit it to the trans, and use transfer punches to mark the holes.

Once I can hook the engine to the trans, then I get to verify that the clutch setup will work. Pictures in my thread soon.

I think the Boxster/Cayman trans is the fix for the high horsepower sixes. But for a type IV, I don't think it's necessary. It is a LOT heavier than the 901, and a lot more work to fit up.

Anyone know where I can get a 12" rotary table cheap? Used is fine. The finish on the big hole in the center looks terrible using a 6" rotary table.