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Sat Dec 29, 2018 1:51 pm

Can you change the gears in the transmission of a VW so that you can drive at Interstate speeds, 65-70 mph? Or is there a transmission that is already made/fixed/changed, that can be bought. What things have y'all done to address this issue.

Sat Dec 29, 2018 2:52 pm

I just drive my bug (with stock transmission) at 67 mph on the freeway. I could go faster (to pass a truck, I go 75 or so, and could go faster, but I just don’t feel like it driving my bug into the 80’s).

If your Engine is a 1600, and well tuned, I don’t see why you already can’t go 65-70 all day long.

Tim

Sat Dec 29, 2018 3:01 pm

A stock VW should be able to cruise at 70mph.

Sat Dec 29, 2018 3:37 pm

To change gears in a VW transaxle requires a complete rebuild. You need special tools and jigs and should be done by an experienced transaxle mechanic. A cheaper solution may be to get taller rear tires.

Sat Dec 29, 2018 6:38 pm

Agreed, you should be able to do even faster than what you want with WOT. Problem is that you are not going to get the MPG you could be getting at 3,000 RPM @ 60 MPH, and to boot engine longevity is going to suffer a lot.

Our 1963 K. Ghia came with the higher geared bus .82 fourth gear instead of the stock type 1 .89 fourth gear. So instead of 60 MPG @ 3,000 RPM we have 65 MPG @ 3,000 RPM. Problem with that is if shifted up into fourth gear at 45 MPH, the engine lugged, which is not good for the bearings. So would look around to make sure all is clear, zip up to 50-51 MPH and then shift up into 4th gear.

Heck with a stock 40 HP engine could easily on the flats get it up to 85 MPH @ 4,500 RPM, but over time found that anything over 3,000 RPM for cruising is not great for the engine. Ending up with low compression worn out engines at around 30,000 to 40,000 miles.

Other way is to go to a higher geared ring and pinion. Did that with our 1960 walk thru panel bus and 1963 S cab type 2s. Went from stock gearing and RGBs getting 47 MPH @ 3,000 RPM in 4th. To later 1964-67 higher geared RGBs and 1973 and later stock beetle 3.875 R&P for 58 MPH @ 3,000 RPM. Installed slightly bigger than stock rear tires for 60 MPH @ 3,000 RPM. Both of these using same stock bus .82 4th gear, with slight changes to 1-3 gears for little to no gearing gaps. With the stock R&P for every 100 RPM increase from the engine, resulted in 1 MPH increase at the wheels. With the 3.875 R&P every 100 RPM increase, results in about 1.5 MPH increase at the wheels.

Along with what MPH you want to run for cruising along, you need to figure out the RPM ranges for each gear you want to run and start doing the math to sort out what gearing you will need to run.

Sat Dec 29, 2018 6:52 pm

Yeah, the earliest year for this Forum is 1968 and that owner's manual says:

That's 78MPH maximum and cruising speed... and it went up a little in later years.

Hell, I was driving my 62 Bug earlier this evening going 65-75, but unfortunately I've not gotten around to replacing my transaxle with a bad 4th gear... and it decided to take a crap on me - the Bungee Cord Trick stopped working to keep it in gear. (Hell, I hit around 80MPH on a tailwind/downhill just a few minutes prior - don't believe me? Here's an image from a dozen years back, same engine/tranny) So I got off the freeway and went home on back roads - even then - I was still hitting 55 in 3rd gear. (this is with a 1385 big bore 40HP engine)

Now I've been planning all year to at least order a replacement transaxle with the "taller" 1967 gearing (4.125 instead of 4.375 differential ratio) which I think will do OK with my current engine but since I have another (econo-performance 1493 SP dual carb) engine I'm building to replace it, I think that will more suitable. I think on Monday I need to make some phone calls.

Oh, and the reason I'm looking elsewhere for transmission work, I have changed a 5th gear on my VW Golf, I've replaced side-gears/axles on swingaxles, nosecones/hockey sticks on swingaxle and IRS Bugs, Bell-housings and input shafts on IRS Baywindow Type 2s, but that's as far as I will go inside. I don't have the training or the precision tooling to delve deeper. But I've read the books to KNOW that you need the training and tooling to go in further.

Suffice it to say: You can't just easily "throw a better gear" in a tunnel-case transaxle.

Heh, as mentioned above, the only really easy way to alter your effective axle ratio is to change to a radically different diameter of tire on the drive wheels. (My 61/66 Baja Bug with 215/75R15 tires on rear, ends up with an effective ratio comparable to 1970s Bugs - and since my Baja and 70s Bugs both have a 1600DP engine, it works great.)

Sun Dec 30, 2018 7:49 am

Search on "Freeway Flyer". It is an option, I didn't see it mentioned.

Sun Dec 30, 2018 9:45 am

Freeway flyer is a damn marketing term. if you have enough horsepower, it's fine but really you should always match your engine output with the transaxle gearing. That's why I've continued to be fine with the 4.375 final drive transaxle in my 62 (well until 4th gear took a shit on me yesterday)

Sun Dec 30, 2018 9:50 am

Just parroting responses I've read here but a concern with those "freeway flyer" transaxles is the lack of rpms at speed which affects cooling of engine. Please consider how you do or will drive your bug.

I tested my speedometer against 4 different vehicles & I (now) know it's off by 4 mph. If I'm accelerating I can easily go to 55 mph before going to 4th gear ... so it's actually 51 mph. My bug is a Craigslist rescue 1971 standard; rebuilt 1776 with 5500 miles, Engle 110, EGAS 38mm carb, 034 clone distributor, tuned by the numbers (not by ear) and unknown transaxle.

I routinely cruise at 75 mph for extended distances. I do not care if I'm passed but I leave PLENTY of distance as I have 4 drum brakes - completely new system & adjusted often. If I can hear 4 clicks when setting the E-brake I will adjust my brakes.

Please be realistic about your intended use of these antique vehicles but first is enjoy !

Good luck ... jinx

Sun Dec 30, 2018 12:44 pm

jinx758 wrote: Just parroting responses I've read here but a concern with those "freeway flyer" transaxles is the lack of rpms at speed which affects cooling of engine. Please consider how you do or will drive your bug.

If engine is lugged (too low of engine RPM) in any gear, even with stock gearing, that is a problem. Really high geared then one might need higher RPM to keep the engine happy. Our buses with the 3.875 R&Ps do best in the 2,000 to 3,000 RPM and that is what we use in the 46 to 60 MPH range. Split bus is also heavier, bigger nose and can carry lots heavier load.

Also one of the few things in the owners manuals is the bad advice from VW that you could drive your VW in way low RPMs that is going to lug the engine. Of course after all VW would be so happy to rebuild or replace your engine when it failed after the warranty expired. If memory serves correctly the 1972 bus was only covered by VW for the first 12,000 miles!

From 1962 OM:

From 1970 OM:

Mon Dec 31, 2018 8:49 am

I'd at least put a tach in it to see what rpm you're turning before you just start swapping transmissions....73 and up single sidecover boxes had 3.87 ring and pinions...they also had notoriously weak reverse gear forks so many got replaced by the 4.11 box you should have now....you may have some other issue that won't let you get up to cruising speed

Mon Dec 31, 2018 8:54 am

There is a reason VW gave it the gearing they did. I'm sure that engine cooling was a factor (but probably not the only factor). Remember that engine cooling fan speed is directly related to engine rpm.

I'm sure there is some rpm where the fan/fan housing flows all the air it can flow but I don't know what that rpm is.

That said 65-70 mph is no problem at all for a stock Beetle. If it's a problem for your Beetle, then fix whatever's wrong with it before adjusting gearing.

Tue Jan 01, 2019 6:29 pm

If the engine you have can't cruise comfortably at 65mph, quit driving it and fix it, or something.
End it's misery for goodness sake.
It only takes maybe 35hp to go that speed.

Sun Jan 06, 2019 4:13 pm

WOW, the engine is a 1641, w/110 cam, less than 2000 miles on a rebuilt engine, it runs great, this is my 18 year old son's car, my Dad had one when I was younger than my son is now but I wasn't into cars then, when he built his. He might be going away to college, only 2 hours away up interstate 81 (posted 70 MPH) The guy we bought it from told us that the "sweet spot" for cooling was around 3500 rpm's, so I figured, with no tach in the vw, YET, that at 65-70 mph that the rpm's would be a lot higher, 4500 - 5000. I was only gathering information, no changes are emanant. THANKS, very much for ALL the information, it is really appreciated. Joe (dad) and Steven (son)

Sun Jan 06, 2019 4:25 pm

I have a close 3rd and 4th in my baja and runs 65 at 3500rpm. It's an 1835 with dual carbs but still has a w110 cam. Also not as aerodynamic as a full body car lol.

Sun Jan 06, 2019 4:27 pm

sjbartnik wrote:

That said 65-70 mph is no problem at all for a stock Beetle.
Better be in the slow lane around here at that speed!