Speedtoys

Unike the autobox, the 5spd as a 'decent spare' is increasing in value. Every trans (auto or not) as a wear out date, but parts for the 5spd are not casually found in many cases anymore.

BUT, should you decide to still swap, drop the $$$$ into completely rebuilding it while you can. More use will just add more $ to parts that MIGHT not be available later.

Zirconocene

I'm not about to tell you what to do, what follows is my experience on what is, probably, a clemetines to tangerines comparison.

I've always felt like my '90 S4 auto feels sluggish. Some of it is likely just that the motor and transmission are up there in miles (160k+), and some of it is likely the suspension, most of which also looks to be original. Other, more experienced, folks than me have suggested that a tired suspension contributes significantly to the car feeling heavy. Refreshing all of this is part of my long term plans, so we'll see how things go. I love the car and don't plan to get rid of it.

All that said, I've had the pleasure of driving a manual converted GTS from @Michael Benno , and it's much more Porsche-like than my car. What I think is interesting is that, when he drove my car, he didn't feel like it was too far off of what his well-maintained '87 was like. So, it's maybe the case that this particular automatic transmission is not my cup of tea. The accessible torque in Mike's GTS is intoxicating, even in 3rd gear, and is something I've never experienced in my car. Someday, in my GT, but that's a different, ongoing project.

My long, long term plan is to figure out how to do what was described above, and put in a more modern transaxle, either automatic (Tiptronic or ZF 8HP) or PDK. There are multiple challenges that will need to be overcome, of course, but driving the 5HP in the Cayman we have is not a terrible experience and it's much more responsive. It's more like what I'd prefer in the 928, but getting there will be a lot of work.

The other option you have that is less permanent than a manual swap is to add horsepower via a supercharger. Transmission be damned, that's reasonably reversible and would be sure to wake things up for you.

Good luck

gazfish

Curious if you’ve driven a manual 928 of the same era to base your decision on, as it’s a lot of work that might not deliver what you’re expecting from the car and reduce its value unnecessarily?

MajorHavoc

Yes I have. While I’m still on the fence I have no doubt a manual would make the 928 a more sporty and fun car to drive for me.

Petza914

The other thing you might want to look into is the Jager Engineering kick down relay mod. Using the thumb button on the shifter, you can trigger a downshift without having to be pressing the accelerator down to the kickdown position. Gives you a bit more control over the gear selection of the automatic transmission. My 84 Euro S has this and I find it useful.

Alan

I don't think a converted Auto will ever garner stock 5-Speed money, and might quite possibly reach less than stock Auto money all other things being equal. The better educated owners would likely be the most skeptical IMO.

There is no all original Porsche parts conversion where you make a 5 speed that is exactly like a stock - because you actually have to modify the chassis to mount the clutch pedal (& master cylinder) and historically that has been a major weak spot both functionally and longevity wise

I'd keep the car as an auto to sell, to just drive or to modify in some other way for power - while hunting for a good manual to meet your needs.

Alan

fiatrn

If you plan to keep it for yourself, then long term resale value has no meaning for your decision.

But only you know your future plans.

Can you borrow an equal year 5 speed and test drive it to see how you like it?

Is your car in peak working order?

MajorHavoc

I have driven a 928 manual. Many times. My background is a service manager, master tech and I run a shop. So the swap is not a big deal for me. From what I’ve seen as far as the shifter opening and the clutch pedal the panels are there and spot welded in. So that’s not a huge deal. If my car was a 100k plus mile car it would be a manual already. But it’s got 50k and very original other than the wheels but have the manhole wheels stored. I’ve changed the muffler and plan on a full exhaust, keeping all the original parts also. I’ve completed serviced the car, timing belt, timing is dead on, new wires, cap, rotor, plugs. The transmission has been serviced and replaced a bad red modulator for a green as per the TSB from Porsche. Everything is dialed in. The trans still shifts like a Mercedes diesel, very clunky. And I would rather be in control of the shifts. But I’ll consider the advice here and may consider selling this car and getting a manual. Not sure yet. Or May decide to swap.

Speedtoys

"The trans still shifts like a Mercedes diesel, very clunky."

Then fix it.

It should not shift like that...nowhere near it.

Alan

You haven't looked properly then - it really is quite a lot of work and most conversions seem to have had issues in initial alignment and in longevity of the clutch pedal mount - don't dismiss these concerns without fully understanding what you are getting into first. Read this thread for context: https://rennlist.com/forums/showthre...eferrerid=6055.

I'm certainly not saying you wouldn't be able do it but it IS actually quite a lot of work - and you can understand that unless you knew exactly how the work was done - as a future buyer you'd reasonably have legitimate concerns... if you are keeping it and will enjoy doing the work - well its your car - do whatever you wish of course!

Alan

MajorHavoc

The trans shifts just like other ones I’ve driven. And I know what’s involved in the swap. It’s not as bad as you make out. And I wouldn’t sell it, if it was manual.

Speedtoys

Then they're sadly out of spec as well...I'd bet 95% are..because they just work, vacuum adjustments, bowden cable adjustments..etc..nobody thinks that they're not "right".

They should not shift like a clunky diesel truck.

MajorHavoc

My Bowden cable is adjusted to spec as is the modulator. There is nothing wrong with my transmission. It works as designed. And the transmission does not function like a performance car it performs like a Mercedes diesel. As that’s what transmission it has. So not sure your argument here.

Speedtoys

You are the qualified Porsche modified Mercedes transmission mechanic, I guess there's nothing else to say.

I had mine entirely rebuilt with the Porsche and Merc updated parts (by a {the} qualified Porsche 928 modified Mercedes transmission mechanic), and it no longer shifts like a 38yr old box.

You will likely find a lot of similar sentiment over what a properly working one is like compared to a 40yr old unit.

MajorHavoc

I’m not here to start arguments and have keyboard egos thrown at me. I’m not going to go into my credentials. My auto transmission shifts fine it’s low mileage and fully serviced and adjusted. In my OPINION it does not do the car justice. I’m sorry your feelings were hurt. In my OPINION the 928 for me would be a more enjoyable car to drive with a Manual. Did not mean to insult your porsche/ Mercedes serviced super trans.