Thaddeus

hey,

How much stronger is the manual transmission in a 951 over that in an NA? I can get a 944 NA really inexpensively, a lot more so than a 951, for the EV conversion, but I'm thinking the transmission strength might tip the balance to getting a 951 donor chassis.

What did Porsche do differently?

V2Rocket

Bigger ring/pinion, tougher gears, taller F/D ratio, totally different transmission case casting...

But they use the same mount

I broke an NA transmission cruising down the highway.
There's a 944-V8 guy with 700+hp who until recently was running a 951S box...he only recently changed to an aftermarket $$$ box so he could have paddle shifters.

odonnell

What torque will you be making? I wouldn't trust the NA trans past 200 ft lbs unless it was in great condition / low miles and you drive like a grandma.

Thaddeus

As much as I can afford commensurate with a 150 mile range.

mytrplseven

Now you're talking about my wife in her Boxster.

lart951

for a electric motor they put huge loads of torque instantly, you will need a LSD at least a AOR turbo S

Thaddeus

You can program the controllers to bring on torque progressively. The torque on the AC motors isn't as aggressive either, but it holds on until higher RPMs. Flatter curve.

lart951

I has a customer that did such a conversion

Thaddeus

They have a blog or thread anywhere?

odurandina

The 944T transmissions have performed flawlessly for 30 years.

mrgreenjeans

turbo S and 89/90 - 951 has a hardened gearset in the lower gears and almost all if not all are 220 coded LSD transaxle assemblies.

They are a VERY robust transaxle, and as noted above have the larger ring and pinion for durability.

I have seldom heard of any breaking. Only one's I have heard about that were hurt, were run low on gear lube or had a synchro break and get ate up and do it's damage internally. Or the earlier ones with a ring and pinion issue.

Dougs951S

I know lots of guys who have broken NA trans, but nobody I know has managed to destroy a 951 box yet. I think with the appropriate controller settings it will be OK. opt for the 951S box with LSD.

IMHO there are probably stroker guys making more torque than your electric motor will ever put out and 951 boxes handle that abuse fine. As already mentioned, they are tremendously strong transaxles.

Thaddeus

I also want ABS and an air bag, since this car (if I build it) will be my commuter (heavy traffic) so I think a 951 is probably the way to go.

The only other car I'm looking at as a potential donor is the RX8.

SloMo228

The RX8 would have the advantage of being newer, and being able to use a traditional transmission, which would give you more options depending on your fabrication ability.

Plus, I have been seeing them go for super cheap with ragged out engines. It's a great chassis, too. I don't think you can really go wrong with either one. I think we're probably a little biased here toward the 944, but the RX8 is a nice handling car with more of the modern conveniences one generally prefers in a commuter car. Dunno how difficult it would be to keep them all in an electric conversion, though.

odonnell

Hah, my neighbor's RX8 died last night... I watched it lose compression before my eyes and it won't start now. Probably a $1000 car now.