Oddjob

Given the same engine rpm: a turbo transmission will transmit 16% less torque to the rear wheels than an N/A trans in first gear, 16% less in 2nd, 17% less in 3rd, 19% less in 4th, and 1% less in 5th (assuming you have a pre '88 0.730 5th gear).

A lot of factors influence acceleration, so hard to say exactly the decrease in performance due to the taller gearing, but it is substantial.

The turbo gearing is excessively tall for a lower powered car, and many consider it too tall for even the turbos - which is why a lot of guys have installed S2 gear boxes in their turbos.

If you dont care about acceleration/performance, and prefer better gas mileage and lower rpm and cruising speeds, then a full transmission swap may be a consideration. Do not think about installing a different R/P into an N/A transmission - even if it would fit (doubtful), it does not make practical sense to do so (cost and effort).

V2Rocket

I was just wondering because I'd assume they were made of more durable stuff than an NA R/P...after hearing so many stories of broken R/Ps I'd like the strongest one out there :-X

Mongo

So you didn't lose your R&P I take it?

Just avoid dumping the clutch, doing burnouts and donuts to avoid destroying your ring and pinion gear.

944CS

the N/A's usually break axles or axle bolts, not R&P's.......this is if you are doing a lot of burnouts. If you're worried about breaking the R&P just shifting through the gears fast, you won't.

V2Rocket

Yea nothing's broken...more of a preventative measure :-X

Mongo

Biblical Rule No. 1 about Porsche ownership

IF IT AIN'T BROKE, DON'T FIX IT.

User 41221

Just for accuracy, a couple of comments.

1) Yes, the 951 R&P will fit in a NA case. I'm still not sure why you'd do it, tho.

2) Yes, '88 and later 951 trannys can grenade. I know this for a fact, from personal experience. And no, I wasn't dumping the clutch for a burnout.

3) Turbo Cup trannys are no stronger than 951S trannys or S2 trannys, and the early ones were considerably less strong (but lighter!). Porsche learned a few lessons as they developed the gearboxes for our cars, in part from what they learned building the Cup cars. The "strongest" gearboxes are found in the '89 and later gearboxes, with the hardened input shaft and some 5th gear magic.

Regards,

lleroyb

You might look for an '88 or '89 NA tranny for the lower fifth, if you really want to try something different. You would have to change the whole transmission, which as said above is probably cheaper anyway. You will turn about 360 rpm more at 70 in fifth, all the other ratios are the same.

I don't know if it is any stronger.

Lou

V2Rocket

How many tenths of a second would I lose if I swapped to a TS tranny?

User 41221

By what measure? 0-60? 1/4 mile? If so, then you've bought the wrong car...

The glory of an early 944 will be found in carving up canyon roads and not by trying to out muscle anything ("anything" includes minivans, dump trucks, or a 4 yr old on a Big Wheel). Its a ballerina, not a lumberjack. Treat it appropriately and you'll be amazed at how well it will perform. Abuse it, and it will dish out more than you can take. The factory tranny/r&p is well suited for the car, in my opinion.

This whole thread can be summed up in one word: "DON'T"

Regards,

MichelleJD

Does the early speedo run off the wheel?

CarbonRevo

Thanks for the clarification Scott. I just thought the Turbo Cup trannys had hardened first and second gears and the 951S didn't (Am I even right as to the Cups having hardened 1st and 2nd gears?).

What all does your transmission consist of again?

tifosiman

I respectfully disagree. The usual mode of failure for an N/A trans is the R&P. Especially if the car has highish mileage or has seen some time driven with the rubber clutch center worn out.

I have yet to break an axle or axle bolt, yet have grenaded 4 transmissions of my own. Of course I use new bolts when r/ring the CV's and check to ensure they are tight. Used/loose ones are prone to break or fall out.

If by "axles" you mean halfshafts or CV's, the 86 951 used the same halfshafts/CV's as my 85.5 and breakage is rare even for the extra HP. Usually the CVs just wear out.

Cheers.

Mongo

How about fluids? Some cars I have heard about have almost NEVER had their transmission fluid changed. This can cause havoc too since the molecules in the tranny oil have broken down and lubrication is compromised.

User 41221

1) Yes, the speedo on the early cars is driven off the front drivers side hub. Later cars have the speedo driven off the tranny.

2) Turbo Cup cars use the same input shaft as the 951S and S2 trannys. The tranny I had Kevin Gross build for my 951 is a special combination of parts, and I had a heck of a shipping bill from Germany.

3) Fluid changes are THE key to longevity in these gearboxes (assuming you aren't in the smokey burnout club). As long as you change the fluid at least once EVERY year (more if you track your car) and use a decent quality gear lube, its should be troublefree for a long time.