TheSamba.com :: View topic - Looking to upgrade transmission... What do I get???

Wed Nov 09, 2011 6:56 pm

from ratwell:

http://www.ratwell.com/technical/FAQ.html

I'm eventually going to an 091 and theres some good info here for what to expect, as well as plenty on the 3 and 5 ribs.

Quote: 4.1 Transmission Swaps:

Transmissions swaps are probably the most asked question. VW engineered in a lot of compatibility but a few snags exist. First the facts:

68-75: 002 transmission and Bosch SR15 starter
76-79: 091 transmission and Bosch SR87 starter

68-71: 200mm flywheel & clutch
72-74.5: 210mm flywheel & clutch
74.5-75: 215mm flywheel & clutch (from VIN 214 2 125001)
76-79: 228mm flywheel & clutch

Vanagons also used the 228mm clutch (NB: from January to March of 1983 Volkswagen put a 215mm clutch and PP in the Vanagon but decided they had to switch back).

Now you know what came from where, what can you swap around? In general if you have a 2.0L engine with a 228mm clutch and pressure plate it will only fit the 091 bell housing. This means to use an earlier transmission with the 228mm flywheel you'll need the later bell housing otherwise you'll need to use a smaller clutch and pressure plate. The 228mm flywheel only engages the SR87 starter which complicates swapping (the earlier starter won't reach the flywheel teeth because of the bell housing...)

The 091 input shaft is slightly longer than the shaft in the 002 transmission used in 72-75 buses but because the 091 bell housing is also longer, the same length of input shaft extends forward from the edge of the bell housing and is therefore compatible with earlier models. The yellow workshop manual says that the distance is 27mm for 74-79 models (no 72-73 data in the book unfortunately). In other words a Type 4 engine will bolt to any 72-79 transmission but you have have to swap flywheels components and the starter.

If you swap an older bell housing onto the 091 in order to use a smaller clutch disc, you will have to swap the 002 input shaft onto the 091. To do this, remove the bell housing, take the circlip out of the groove and slide the gear and the circlip up the shaft so you can turn the shaft to undo the stud holding it on.

Because the 091 bell housing is longer the 76-79 cases have longer studs on the bottom. To use the 091 on a 72-75 case, you must install the longer studs.

However, the 091 transmission as a whole is about an inch longer than the 002. This means that the transmission sits further forward in the bus. If you use the 091 transmission in an earlier bus then the shift-rod will be angled backwards slightly. If you use the earlier transmission on a later bus then the shift-rod will hit the parking brake.

You may have to swap shift rod parts in order to get the shifter into the correct position. The shift rod changed in 74 so you can borrow parts from 74-75 and 76-79 setups to help accomodate the change of length of the transmission as well as make your own mods.

The input shaft of the 68-71 transmission is shorter than the later models by 11mm because it needs to engage the pilot bearing sitting in the gland nut of the Type I engine. If you use this transmission with a Type IV engine the input shaft will not engage the pilot bearing properly and will chew up the needles. The workaround for this is to machine the flywheel opening in order to press the pilot bearing into the flywheel instead of the crankshaft.

On page 435 of the latest edition of Muir, John Hilgerdt recounts the story of a 75 transmission that chewed up the pilot bearing of a 78 bus. There is no good reason for this because the 228mm flywheel won't fit a 002 bell housing so a compatible flywheel must have been used.

I can only speculate as to what parts they actually used because the input shaft is the same length and the pilot bearing is the same distance from tip of the input shaft among Type 4 flywheels. What seems more probable is that they used a 68-71 transmission but since the 68-71 flywheel won't bolt onto any Type 4 engine, they used an incompatible flywheel so the parts mismatch to make it "work" was horrendous!

Using the 72-79 transmission with a Type I engine necessitates swapping the input shaft (and bell housing in the case of the 091) because it's too long and the shaft will bottom out in the gland nut.

To remove the transmission undo the following:

undo clutch cable
remove backup light switch wiring
uncouple the shift rod from the nose cone
unbolt transmission ground strap
remove starter or disconnect all wires
disconnect the axles by undoing the cvjoint at the flange on each side

How about a 5 speed?
4.2 Gear Ratios:

To compute your speed based on the gear and engine speed use this simplified formula:

MPH = RPM * TIRE HEIGHT / GEAR RATIO / R&P / 336

For example: 3400 RPM * 26 / 0.89 (4th) / 4.571 / 336 = 65 MPH

Download this spreadsheet. It shows all of the gears that VW transmissions can be built from and the road speeds they produce at various RPMs. The stock 091 gearing is highlighted.

091 Gear ratios (Miles)
091 Gear ratios (KM)

These are the stock gear ratios for US models:
Code / Ribs/ VIN / 4th gear ratio / R&P ratio /Final
CA-CD / 3 / 218 000000 - 213 2 068547 / 0.821 / 5.375 / 4.413
CE-CL / 3 / 213 2 068548 - 213 2 300001 / 0.889 / 5.375 / 4.778
CM-CN / 5 / 214 2 000001 - 215 2 300001 / 0.889 / 4.857 / 4.318
CP-CX / 6 / 216 2 000001 - 219 2 300001 / 0.889 / 4.571 / 4.064

There is some debate whether or not all 73 models had the 0.821 4th gear or whether the cutoff VIN is higher. The table above is what the factory published in the US.

Tue Nov 26, 2013 4:53 pm

What size tires on that 6 rib trans?

Wed Nov 27, 2013 8:27 pm

MaddMatt wrote: I have a 71 bus, 1776 with weber progressive. I'm looking at upgrading the transmission in the next month or so. I need something that will work better on the freeway. I have a good transmission guy nearby that recommends building a freeway flier out of my current 3 rib transmission. Yesterday, my neighbor of 28 years walked over to tell me he's had a bus transmission sitting in his garage since the mid 80's. It's a 5 rib transmission. Should I go freeway flier or just slap the stock 5 rib in my bus???

I have exactly the same engine and carb and 71 bus with 3 rib transmission.

I would not want anything except the 3 rib transmission.

I have enough trouble going up hills, and 65-70 down hill is fast enough!
It is the perfect transmission for your bus.