which tranny? porsche or jakes?
 

is anyone using one of jakes trannys? i thought of using a porsche, but im not convinced. a 5th gear would be nice for cruising.i want an engine from 180-200 hp. so from experienced minds what should i be looking for?

neil

i have a jake tranny, but haven't run it yet so can't speak from experience.

The 930 Turbo had a 4 speed.......reason was it had so much torque that it did not need a 5 speed....Same with a TIV.

A Porsche gearbox is a hellacious conversion and still has a weak 1st gear...for twice as much money ATLEAST!

My tranny's are set up for a TIV to bolt directly to them and have a few little things that makes it even easier like the correct length operation shaftand most of all the gearing you need for your tire sizes and engines powerband.

Hello-

Having 5 speeds is a wonderful thing :-). A good cruising gear can be had with a 5- or 4-speed box... that's not the issue. The issue is that the 5-speed box has much lower rpm drops than the 4-speed one from low to high gear. The difference is VERY notable... no 4-speed box can ever make up this difference.

The Porsche conversion isn't *that* much of a pain... several have done it. The weak point compared to VW, most of the time, isn't 1st gear at all. Rather, it's the engagement stuff... if you try to slam and force gears all the time (a la drag racing), the Porsche box will hate you - oddly enough, the VW one, although still unhappy, will be less unhappy.

The 930 turbo box is very strong, but the gearing is pretty sucky for most applications. By the mid 1980's, when the rest of the sports car world caught up to Porsche, the 4-speed box of the 930 was a pretty bad selling point... Porsche *finally* gave it up in 1989. It is a very popular idea to get a 5th gear in old 930's... a properly regeared 5-speed tranny makes them accelerate notably better!

Take care,

I have no experience with either box but just for another point of view that kind of aligns with what Jake said, I test drove a few Miatas once. The later years have 6 speed boxes. The 5 was fine but 6 was just a pain in the butt. It was just too many gears. To get up to freeway speed you have no choice but to go through all 6, but the engine is never telling you its time to shift. Maybe for racing it would be different but for everyday driving, more gears are not always better.

Ron

Hello-

I have no experience with either box but just for another point of view that kind of aligns with what Jake said, I test drove a few Miatas once. The later years have 6 speed boxes. The 5 was fine but 6 was just a pain in the butt. It was just too many gears. To get up to freeway speed you have no choice but to go through all 6, but the engine is never telling you its time to shift. Maybe for racing it would be different but for everyday driving, more gears are not always better.

Aye... that's why street cars don't have 7-speed boxes like F1 :-).

But... 4? C'mon. How many modern production cars (let alone sports cars!) have non-automatic 4-speed trannies? I can't think of any offhand...

The common thing is to use a 1.26 3rd and .82 4th in a "freeway flyer," right? That's a 35% drop in high gears! That sucks, big time!!!

A 4-speed VW box can be quite a bit cheaper... this is true... and if you plan on slamming gears every day its engagement goodies will live longer. However, I can't see any other advantages.

Take care,

Well, there is a sequel to that story: in those days a company called Ruf in Germany made the first 5-speed turbo boxes when the Porsche factory only offered 4-speeds. Once a turbo-customer test drove a 5-speed, they all wanted one. In fact, he sold so many, he could start his company with just building 5-speeds. After the Ruf succes story, the porsche factory also decided to offer 5-speeds and Ruf started to tune 911 engines as well to cope with the 'competition'.

Walter

My F-450 has a 5 speed and needs more. Often I have to choose between too low or too high of a gear, but that is the problem with a vehicle that wieghs anywhere between 8000and 16000 lbs. My Ghia has 1.26 3rd and 89 4th and the drop is no problem at all. An 82 might be pushing it. I'm really hung up on the 3.44 RP myself. Personally I like a good spread and an engine that loves to pull. I like enough spread to really savor each gear. A good 2-3000 rpm in each gear gives enough time to say OOHHH YEAH. :) The stock gearing on the later years is really evenly spaced if you plot speed vs rpm in each gear. With a 3.44 coupled to an engine like Jakes 2270 I think would be well matched for pulling and 4th gear cruising.

Ron

It may not be that much of a pain to install the 901 gearbox, but it's very far from a bolt-in deal! There's still quite a bit of fabrication that you have to do from what I have read.

A Raby gearbox should be a true bolt-up-and-go install. A couple of orders of magnitude less time.

So, on the one hand you have five gears that are set up and spaced for a six-cylinder engine with a given power and torque curve. You also have quite a bit of cutting and welding and making of parts to get it installed.

On the other hand, you only have four gears. But they have been chosen specifically for the engine that you will have (assuming you're using a Raby engine, at least!) that play well with its power and torque curves. And you have a no-brainer bolt-in install.

Doesn't sound like a tough choice to me....

--DD

What if that Raby tranny was converted into a 5 speed?

Wouldn't that be the best of both worlds?

Hint, Hint Hint!

cont... of porsche or jakes?
 

ok, i started a thread in the aircooledtechnology forum, it wouldnt let me add to it so im bringing it here

http://www.germanlook.com/Forums/sho...&threadid=3176

so .....

ive read that a porsche 5 speed can acutally rob the engine in 5th gear. that the gear causes the engine to work less, which slows the fan which gets the engine hotter, in turn robing the longevity of the engine. read this on bergs site

so one could open the 5 speed and pick the rigt gears, bu thn the price to do so doubles, an now your not even to the point of modifing the suspension and pan to accept the tranny.

so now i lean toward a tranny built for my car, that fits and has a builder that will stand behind it.

did i miss something? once again, other than just to do it. why a porsche when it cost more, more involved in fabrication, and is a thorn in your engines side? why?

let the respones flow, an please correct me if any of my statements are incorrect, as im just trying to learn from you guys.


neil

My mistake......

I moved the entire thread here and merged with your new one.

Alex

I run a porsche 911/01 5 speed gearbox in my 1303 (2L t4 engine, tuned up a fair bit).

Yes it takes a lot of work to get it in the car. between me and my Dad we had about 90 hours fitting the gearbox alone (2 of us for 45 hours total). If we did another one it would be much quicker, and if the body was off the pan it would have been much quicker too.

Would I do it again.... No. I would go the extra mile and fit the 915 gearbox :D

I simply love the gearbox, combined with the engine its wonderful. Simply a pleasure to drive, 5th gear only really get used on the motorways (freeways) at 80+ mph...

The only thing I DONT like is that I know if something goes wrong it could be expensive....

Cheers for now,
Sam C

Neil, Reguarding Bergs info, or anyones for that matter, Beware of blanket statements. Gearing too high can be a problem with overworking the engine if the engine is not matched. Also he is talking about engines with stock cooling, which to him was set in stone. To improve cooling was "putting a bandaid on your elbow blah blah blah." I would like to see one of his engine kits on Jakes dyno with his typical 40 minuit 80 HP load. If it could handle that I bet the porche 5 speed would not be a problem.

Ron

actually the 5th gear in the 901 box is .82 i believe.

right around the taller end of stock 4th gears on type1 VW boxes.

my car is at the shorter end of the stock gear spectrum.

its a 73 with the single side cover box (1.26 3rd and .93 4th with the 3.78 mainshaft and 4.12 R&P)

the 915 turbo boxes had like a .62 4th and somewhere around a .85 3rd. basicly a double overdrive 4speed