RPMs - Worth the transmission swap?

[ghiachimp]

I've been considering the pros and cons of swapping my 4.375 code AM transmission for a 4.125 of some sort in order to stop the engine revving so high at 60mph+

I used this: http://www.csgnetwork.com/multirpmcalc.html

If I'm inputting the numbers correctly, it seems there'd only be a reduction of just under 200rpm. Will that really be noticeably different in terms of noise and wear and tear on the engine?

Ring Gear and Pinion Ratio = 4.375
Tire Height = 25.39" (165/80 15s)
MPH =60
Transmission Final Gear Ratio = 0.89
Resulting RPM = 3092

Ring Gear and Pinion Ratio = 4.125
Tire Height = 25.39" (165/80 15s)
MPH =60
Transmission Final Gear Ratio = 0.89
Resulting RPM = 2915

Engine is a 1641cc, everything else is stock.

I'm leaning toward thinking it's not worth the hassle but i have no experience in this area, if I go over 60mph it just sounds like my engine's going to explode! Any views appreciated!

[Root_Werks]

Someone on theSamba showed me this link, I really like it:

https://www.blocklayer.com/rpm-gear

My Mexi-Bug originally came with the 4.37R&P and I think a .93 4th. It was terrible on the freeway. I think a 4.12 with .89 would be much nicer with a 1641. You'll be happier.
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When I set my timing, why do I flush, then take a pee?

[gt1953]

Remeber it is an air cooled motor so you need to have the RPM to spin the fan to keep engine cool.
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Volkswagen: We tune what we drive.
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72 Squareback
({59 Euro bug, 62, 63, 67, 68, 69, 73 type ones 68 & 69 type two, 68 Ghia all sold})

[ghiachimp]

Understood on the need to keep the revs up to keep the engine cooler. From what I’ve read the sweet spot is around 3000rpm at 60mph. It just feels and sounds that my engine is under a lot of strain at that speed.

This is a car which is relatively new to me, the rebuilt engine is only just run in but it pulls well in the lower gears and really purrs along at 45-50 mph. My other Beetle has a 1200 transmission (don’t know code) and a 1600 engine but seems to handle higher speeds easier. Both are swing axle.

I have an opportunity to buy an AO code transmission. I mostly drive on slower roads so swapping the box is a lot of effort for something I might only benefit from from time to time.

That’s why I’m curious if having the engine spinning 200 rpms slower will make it sound and feel that different.

[Starbucket]

Remember the VW motor was designed after an airplane motor so it will run reliably at RPMs up to 4000 all day and not complain, if you lug it down you will pound out your main bearings because the case was designed for free running RPMs.

[vwracerdave]

VW used the 4.12 R&P gear with the 1500cc single port engine so yes your 1641 can handle it.

Yes it would be worth the effort only if you do a lot of long distance driving at 60 MPH or faster. With the 4.12 you will get slightly better fuel milage.

You could accomplish the same thing by keeping the 4.37 R&P and getting larger rear tires.
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2017 Street Comp Champion - Thunder Valley Raceway Park - Noble, OK
2010 Sportsman ET Champion - Mid-America Dragway - Arkansas City, KS
1997 Sportsman ET Champion - Thunder Valley Raceway Park - Noble ,OK
Featured in Dec. 2001 HOT VW's Magazine page 63

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[Bruce]