5-Speed?

[TWhite]

Hey gang. I love that my Sebring does 80 easily (with a stock 1600cc), but it sure does need to wind up a lot to do so...somewhere a little over 4k rpm. I'd like to be able to drive 80 for a good distance without straining the engine too much. I've read about the heat issues with a 5-speed tranny and an air-cooled engine. How does that apply to these cars (being so light and better air flow)? Is the 914 tranny the way to go here? Anyway, the overall reason is that driving on I-25 from Denver to Colorado Springs is a 75mph zone that everyone seems to ignore. So the average speed is usually 80 when it's not rush hour...and I don't want to look like one of those slower cars that can't keep up with the flow of traffic

 

[letterman7]

Hmmm...first time I've heard of a heat issue with using a five speed. You could do the Porsche 091, but then you'd have some frame issues to work with. The simplest, quickest and easiest is to order a basic freeway flyer from a reputable builder, like Rancho. For about a grand or sometimes even less, you can get what is essentially an overdrive 4th gear, lowering your rpms. A/C engines are meant to wind out at cruise - it keeps them cool. My little 4-banger in my Rabbit - an automatic - cruises at 3500 at 65 mph. And it struggles more than my Sterling with a 1300 did!

 

[TWhite]

yeah, the heat issue was a Berg philosophy. Something about exerting the same horsepower to maintain a speed but with less RPM meaning the fan isn't spinning as fast, resulting in more heat. I saw a Type 1 freeway flyer for $425 (exchange) on the Samba. I might think about that. Do they just have an overdrive 4th? or are 1 through 3 regeared too? My thinking on a Porsche 5-speed is that I MIGHT end up with a different engine, like a water cooler something. I'm sure any engine would have to spin as fast as this one to maintain a higher speed. I know 4k RPM isn't too bad, but I thought maintaining that rmp may end up being harsh on the engine and I don't know how that'd effect a different engine. I've read an article on getting the Porsche tranny to fit. I think it'd be easier to fit in the Sebring than a Beetle since I have room to move the engine back a couple of inches...although I'm not positive, haha.

 

[letterman7]

I'm not sure about 1-3. I guess you could spec just about any combination, but if you're doing mostly highway driving it shouldn't matter. If you're thinking of a different engine, then talking with the builder would be the best route, since they could tell you the best combination for the trans. Don't forget to tell them the rear wheel sizes for the calculations.

 

[GreazMonky]

if i remember right, the freeway flyer transmission just has a different 4th gear. i was going to put one in my sebring, since i have a v6. i have been thinking of doing a 5 speed conversion as well. i only get low 20's on the highway, i sit at 3k doing 60. but i figure that i could just swap the 4th gear on mine as well.....might be a lil easier

 

[ydeardorff]

I know this is probably a bit overly technical as a response, but when choosing a new transmission you could find out what you hp and torque curves are for your engine, and then choose a gear set and final drive that will place your RPM's exactly, or close to where you want them at freeway speeds.
On the Subaru gears website there is a wheel profile/gearing and final drive calculator you can use that will give you a better idea of what various wheel sizes, and gear sets will give you the results you want.

FAQ
Look at the bottom of the page.

Changing the size of your tire/wheels will change your RPM at 60mph, as well as changing the gearing and final drive.

So if you know or can find out what RPM the VW engine runs the coolest, or most efficiently then target that with your choices.

 

[RangerBEH]

I keep debating if I should get a freeway flyer with a 1600 dualport, dualcarb engine. Id hate to finish the car and then be pissed off I can't do 80....

I don't have the 75mph speed limit excuse, I just have a lead foot

 

[letterman7]

Save your money on a freeway flyer. I bought one - supposedly rebuilt - and found that is has the same basic ratios as a late model Super Beetle. So.. cheap trans swap - find a Super Beetle trans. They have something that is desirable in a VW transaxle anyway - a stronger input and pinion shaft.

 

[Peter]

I blew up my 1300 gearbox in short order so I pulled a1303 gearbox and changed it to swing arm, basically just the side plates etc and it was less hassle and expense that going IRS and no problems sitting at 70 mph all day long and that was with a standard 1600 with dual DellOrto 36s, I now have doubled the HP on the 1641 and rebuilt the engine with everything tuned, ported, balanced, dropped forged, H beam rods, etc so I can rev it and use the power, the only reason you can't rev a standard VW boxer is component integrity, balance etc, it would just crack up, overcome that and you can cruise at 4K all day long. The only thing I will add to mine is a welded and balanced fan.