What are the differences between a 901 and 915 trans

[cmcfaul@aol.com]

What are the differences between the 901 and 915 transmisions?

Is one better, stronger or faster then the other?

Thanks,

Chris
73 911 E

[cmartin]

915 has a standard pattern, compared to the dogleg'd first of the 901. 915 is stronger and heavier too.

[racer]

"faster" ? I guess you could say a 915 is faster because you won't mash the trans on the 1-2 shift like you would on a 901. Overall though, Porsche transmissions are not known for their "speed".

As mentioned, the 915 is also stronger, although both applications have handled over 200hp.. it's then just a question of longevity.

[Trak Ratt]

Chris did you brake your 915 and are now looking for a cheaper replacement?
There is actually (3 or maybe more) trans in this group. The 901, 911 and 915 are peaty interchangeable as far as size and gear sets. Internal parts are different. Later 915s had higher final drive ratios so would also have a theoretically higher top speed. I believe the 901s have smaller clutches than either the 911 or 915. So if you retro with the 901 you would need to make sure the fly wheel and clutch matched the case. The 915 is “rated” for higher torque but the 901 and 911s worked with stock Porsche HP to 180+. The 5 speed 901/911 are also known to have a “weak” 1st gear. The real wild card is the 911 trans. Based on the 901, but with a completely different clutch setup including cable. There are plenty of 901s (teenr’s use a variant) around with big HP motors. The secrete seems to be; easy off the line, no power shifting, narrowish tyres;)

[cmcfaul@aol.com]

Thank for the responses. I am not sure what is in my car. When my father bought the car in 74 it had a 4 speed. The car he was replacing had a 5 speed so he swapped them (normal H pattern).

The plot thickens. I had the transmission completely rebuilt a few years back (Porsche Pit Stop in Alexandria). They replaced all the sychros, brake bands, roller bearings, etc. They said they could not get parts for my transmission anymore so they used 915 parts, I believe.

Third gear sychro is weak and I am contemplating having it replaced but am not sure what I have.

Chris
73 911 E

[William Miller]

What's a brake band?
Does it stop things from spinning when you push in the clutch?
Most useful for not grinding 1st and reverse?

[Vicegrip]

Could not get parts is Bullshit, period. You name the 901 or 915 part and there is someone selling it.
Get under your car and look for the rib of metal that runs doen the center of you gear box. There is a stamped # on it. NOT the one cast into the case on the side, the # you need to get is on the bottom and is stamped into the metal rib. This # will tell all about the gearbox. What it is what it originaly came with as far as gear ratios and the like.

[Trak Ratt]

If a 5 speed with first to the left and up and reverse to the right and down then it is a 915. Numbers on the trans would be 915/02 if ’72 or ’73 trans.

[Eli]

I have some variant of a 914 tranny sitting at home. Anyone interested, it's yours. No clue what it's worth or condition it's in.