I've decided to keep my 5 speed 901 sideshift in my project plans for the big 3.2 transplant...I know...I have to notch the housing and it's going to blow up....anyways....

Now, I have an opportunity to get another 901 5 speed from a 1968 911 as a spare...or possibly a donor (as I have not yet pulled my original 901).

Q: is there much difference in a 914 901 and a 911 901?

Q: What is a (non refurbished) 911 901 worth in this scenario?

Q: What parts do I need to make the 911/914 switch?

I will be using 911 SC axles/cvs...

Q: which cv/transmission flanges do I need?

Don't be shy... lemme have it...both barrels.

Cheers,

Sean

You will need to flip the diff on the 911 901. The advantage I see is perhaps better gear ratios? I'm not sure, and don't have a chart on hand to see if the ratios are different between the two.

I was able to repeatedly break the diff at 160HP in the Thunderbus. The diff is substantially smaller than the 1969+ diff, the case is a bit more fragile, it has the infamously weak 12mm threaded end on the mainshaft, as well as the early (troublesome) synchro inner bits. Dumb idea. BTW, it's worth about $125 as is, more if it comes with some kind of guarantee as to it's condition. Shiny case, though ...............

The Cap'n

1976-1977 915 coarse spline output flanges

I would start with a 914 sideshifting 901. I would do the billet intermediate plate and make sure the bearing races in the trans are not loose in the case.

Forget the early 911 trans. Get a couple 914 transmissions for parts.

I ended up breaking 4th gear sets when doing track work with 914 transmissions on a stock 3.2.

I believe that it is not the HP, but the torque that tears up transmissions.

I know that on the street, the 901 should last pretty well unless you must do burnouts in 1st.

just my $0.02

I don't know what your time frame is but I have a completely rebuilt 901 with a tall 5th already installed in my car. It was built and test driven for about 5 miles and went to the paint shop.

I have been working on a 915 that I was planning on installing next year and it is way ahead of schedule so I may yank the 901 out immediately after it returns from the painter and install the 915.

It also has a new Kennedy clutch set up as well...all new.

Pm me if you might be interested in it. Looking at about 6 weeks before it's available..

Here it is...
Click to view attachment

Good advice, ALL.

I have only ever had 915s in my 911s and never worked with a 901...(i was told to avoid them)...

I'll tell the guy he can keep his '68 901 as a boat anchor...and down the road some I will look about for a solution.

Paul, thanks for the offer, that tranny looks great. I'm just starting this 914 resto, and I'm nowhere near finished drivetrain components. I only was looking at the other 901 as it is my nephews friend that is cleaning out his garage after a taildragger resto...and I could steal it cheap.

Ok, let me get this straight because all I have ever heard is that the 901 is good up to about 300 HP, anything more than that and it will grenade.
I figured that I was completely safe with the Suby conversion getting me in the ballpark of 170hp and 165 ft/lbs torque. Now after reading through this new doubts pop up.
I have a freshly rebuilt 73 901 with all stock ratios and parts, no beefy intermediate plate yet. Is this a safe match? A burnout would be nice now and then, especially next to some punk ricer with a fart can and 150lbs of extra ground effects... hehe...

Hate to hijack but its realative to the discussion at hand I think...

It is my opinion that no 901 or 915 box is prepared to LAST when doing burnouts. Will they do it? Yes. Will they break? Yes.

How long an abused trans will last depends on how abused it is. How wide/sticky are your tires, how much torque do you have ?

A 901 box will last for some time when coupled with a stock 3.2. I know because I have done it. I think it will last on the street for even longer (I'm banking on that right now).

Why do you think you want to do burnouts? I have always used the theory that 10% wheel slip is about the limit of adhesion for typical tires. (Braking, accelerating, cornering)

I'm too cheap to waste my tire money on some silly demonstration of speed (that you can get a ticket for by the way).

just my $0.02

I guess I'm still not too cheap for silly demonstrations...

It would also be nice to know that I am not riding on the fine line of something going "snap" if I ever decide to get on it for ANY reason. Launches at SCCA I think would be worse than letting the tires slip and smoke a little.

Does this mean I need to be planning a 915 swap in the future?

My 03 Cobra has a Tremec T-56 Transmission. The car makes 453 RWHP. Running 315 rear tires I can brake this transmission if I do burnouts from a 65mph roll on the highway. Been There Done That. Got a broken tranny in the basement to prove it.

Don't be an idiot. The Tremec T-56 is the same transmission in the Viper. If it can be broken, so can a 915...

I know guys in the Cobra Club that can do standing Wheelies with less than 100 more HP than me and skinny front tires.... My car is too heavy as it is a Convertable.

IF you want to do burnouts, get a muscle car. But you will still have to fix it too....

Want to have some fun, take your 914 to run the Tail of the Dragon... Thats where I am going this summer....

idiot, nice....

Ok, obviously I hit a chord with the word "burnout". Sheesh, touchy crowd today... I just remember the infamous Suby-swap (b-word) video that was posted on the other board, seemed to get nothing but kudos and praise...

http://renegadehybrids.com/914/Subie/Videos/Video01.avi

I'm not saying that it will break the first time or the second, but with enough brutal launches, the trans will not last period. (just ask anyone that has been pushing these transmissions for 20+ years)

If you want to abuse a Porsche trans, buy a good one like a 930 box.

It will cost money, but it can handle a bunch of torque and HP.

Something that will reduce the stresses on a trans if you want to do ricer burnouts: skinny crappy tires with little grip.



Either that or get an American automatic transmission set up specifically for drag racing and 1000+ HP.

Porsches were never intended to go drag racing. More finesse and capable of doing more than going in a straight line.