Vanagon 4th gear visual: is it a .82 or .85?

[jimf909]

Can anyone confirm that the 4th gear (Vanagon 2WD manual 4 speed) in the picture below is a stock .85 4th gear?

41 teeth on the small gear / 48 teeth on the big gear = .85 which seems to be the stock ratio. Is that correct?

Thanks.
_________________
- Jim

[Sodo]

41/48=.8542

99% sure them’r OEM gears.

Smaller teeth are quieter, last longer. Provided they’re not being overloaded. My preference is smaller teeth cuz I’vm driving an RV, not taking jumps and landing with pedal-to-the-metal.

.82 4th (Weddle gears) have much bigger teeth. Big teeth are better for racing, shock loads, are noisier, and don’t run as long (on the highway). But less likely to bust in racing.

The bigger gear is called the “4th gear idler”. It spins on a needle bearing when you’re in 1st, 2nd, 3rd. When in 4th gear this idler is locked to the mainshaft by the 3rd/4th hub, thus its needle bearing is like a “spacer of cylinders.”

Smaller is called 4th gear pinion. ⚙️ Its splined directly to the pinion shaft (to the “P” of “R&P”. The “smaller gear of a pair” is called the “pinion”.

I’ve always been curious what is the purpose of the circumferential grooves. There’s 3 on the idler & 3 on the pinion.
_________________


'90 Westy EJ25, 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb

[jimf909]

Thanks for the explanation of the different gears.

This trans has 292K miles and was rebuilt once before in 2005 so there’s a good chance this 4th gear is new (edit! Steve Jobs thought I wanted to spell “new” when I spelled “oem”. O-E-M. Go back to sleep, Steve).

I’ve wondered about the grooves as well. My first 100% uneducated guess imagines they have something to do with oiling. That or noise.
_________________
- Jim

[Sodo]

Jim I can’t think how it would oil any differently. They are certainly an intentional feature that has a cost therefore “a reason”. Maybe “gears” knows this one. He’s been preoccupied these days.

My 100% wild guess is something to do with VWs gear supplier/mfg or maybe dimensions/tolerances. Where the best tranny is built of gear pairs chosen with same # of grooves??

Another guess. They use a tool called a “gear hob” to cut teeth into a gear blank. Maybe the first 1xxx (new hob) get one groove, next 1xxx get two, then three etc. Where if gear tolerances aren’t working out, they know which gears came from which stage in the tool’s useful life.
_________________


'90 Westy EJ25, 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb

[gears]

The tiny grooves are merely to quickly pair the gears, and know which ratio they are.
_________________
aka Pablo, Geary
9.36 @ 146 in '86 Hot & Sticky
'90 Syncro Westy SVX
'87 Syncro GL 2.5
https://guardtransaxle.com

[Sodo]

Dang the conjecture was more interesting....

Seems odd though, that anyone building these tranny’s would need an indicator. Wouldn’t it be .85s all day long? All week, or all year? Its not like the bolt &nut aisle at HomeDepot, where people pick them up then toss’em back in any old bin.
_________________


'90 Westy EJ25, 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb

[E1]

Never realized our gears were so groovy.

Sodo, curious about your theory on larger gears going less highway miles. I would think the opposite; bigger, stronger, and all that.
_________________
‘84 Westy, 2.1L with Digijet, 5.43 R+P, GT Gears
"Adding power makes you faster on the straights.
Subtracting weight makes you faster everywhere."
— Colin Chapman

[jimf909]

[Sodo]

[E1]

Thanks, Bud. 👍🏼
_________________
‘84 Westy, 2.1L with Digijet, 5.43 R+P, GT Gears
"Adding power makes you faster on the straights.
Subtracting weight makes you faster everywhere."
— Colin Chapman

[gears]

VW went to fine-tooth "low loss" 3rd & 4th gears during the '70s. Although the individual teeth weren't nearly as strong, the increased "overlap ratio" (number of teeth engaged) made up for this, for the most part. However, breakages would occur when the vehicle was subjected to abnormal shockloads.

When VW introduced the waterboxer engine with increased horsepower (and greater vehicle weight), VW also went with somewhat larger 3rd & 4th gear teeth.

Breakages may still occur, but not nearly as often as with the earlier gears.
_________________
aka Pablo, Geary
9.36 @ 146 in '86 Hot & Sticky
'90 Syncro Westy SVX
'87 Syncro GL 2.5
https://guardtransaxle.com