Manx Club

Ok so I'm starting to think about a Bus Trans for my buggy, can anybody tell me some basic's 3 rib 6 rib,models/years, pros/cons
Thanks

3 rib are generally lower R/P ratio.  Some early ones are 5.38/1.  Some say they are lighter weight than the 6 rib.
6 rib (091) were from 76-79 and most were 4.57/1 R/P. General consensus is they are stronger than the 3 rib.
1st-3rd gear ratios are the same. 4th varies depending on the year.

Check type2.com in the library section.  Lots of good info.

Joe

The bus transmission that is the most common is the one called a 3 rib. The ribs are across the top of the differential area.
3 rib trans came with 5.38 to 1 ring and pinions as the most common 5.43 to 1 was an option and not very common to find.
One 3 rib to stay away from was the 1968 one year only. The differences on exterior was 6 acorn nuts around the CV flanges, interior wise there were a few one off parts that are not longer available.
All other 3 ribs have 2 philips screws on each side of CV flange.
3 ribs depending on what year it came in used either 113 or 002 gears. The 002 used a stronger 1st gear.
The 5 rib also called the pyramid because of shape of ribs. They were only used for 2 years 1974-1975 and came with a 4.86 ring & pinion. Used 002 gear sets.
091 trans came with 6 rounded ribs. These where the strongest in some respects. 4.57 ring & pinion with option of a 5.43 R&P. Length of transmission was approx 3/8in longer than other bus trans. Also used longer engine mounting studs and bolts. Starter was also different from bug type starter.
1972 and later trans came with longer mainshaft because pilot bearing in type 4 engine is end of crankshaft instead of using gland nut. Longer shaft can be cut shorter without taking apart trans using 3in cut off wheel.
The 091 that came in the 1980 Vanagon shifter came out the side of the nose cone ( shift housing)
Later Vanagons also had a side shifter that came out the the side of transmission case. These 2 different styles can be used but do require using a different style of shift linkage.
There also a 5 speed version that can be used. Jon uses one in his orange Manxter and made his own linkage.
091 transmission bell housings can be changed out to the earlier bell housing.  The only oddball one is the 1968 which is a little different in design.  It will bolt up, but may leak oil at seams.
You can use a 200mm 12volt flywheel in a 091 bellhousing which is design for the 228mm flywheel.  091 starter has to be used. 
None of them can flop the ring gear from side to side for reverse rotation.  They are Hypoid design. 
I have seen them mounted upside down in a midengine buggy.  Does require machine work as mounting points on VW engines are not symetrical on top and bottom mounting points.
Used Bus transmissions are becoming harder to find. Rancho Performance has agents buying them up everywhere.

I've come across a 69-71 3 rib, and I'm trying to decide if it's worth it, It will eventually end up mated to my corvair(I'll reverse the rotation). If it uses the 113 gears is it any stronger than a type 1 that uses the same 113 gears?

The gears inside the transmisson part are not any stronger.  It still used the weak 1st gear.  
One thing to remember when using a  the early bus transmissions with the 5.38 R&P  (it easy to check ratio by removing bell housing and looking at numbers on ring gear) is that if you plan on crusing on the hi-way using a 31in tire will not allow more than approx 60MPH without over revving the engine.  33in tire is just about right size.

I don't know if I want to exceed 60mph any way,LOl. I think i'd rather the lower gears for trails/hills. I found an ID # 002.301.103D any body help with this? can the weaknesses can be addressed?

The early 1st gear is weak yes, but can last along time.  If you side step the clutch pedal, stand on the gas pedal from a standing start, after jumping the buggy you never let up on the gas then you are going to break it fast.  There are many buggies with large horsepower use the early 1st gear with no problems.
The later 1st gear went to a 9 tooth from 10 tooth on the mainshaft which added strength, but still can be broken.
Aftermarket 1st and second gear sets go for around $600.00 for the set.  They are very strong just more money than most people want to spend.
VW change to the later 1st gear in 1972 when they went from the Bug engine to the Type 4 engine with the added torque. It was also used in the 1973 Bugs.
The number you posted is just a part number.
The code for different transmission in below the fill plug on the side of the trans. 
CA was early  can be with or without throwout bearing sleeve. 1971 was first year for sleeve.
CK was use in 1973 (I have one of these and it came with the later style mainshaft with stronger first gear, it not for sale was race box with all gear ratios changed)
CM 1974
DK 1980  091trans

Ok great info Thanks, from some pix it looks to me like an early style TO bearing not the sleeve type, but this is ok since the crovair/vw adapter stuff I have came off of a T1 setup, plus I might be able to pick it up for around $200.00

Ok so I picked up the trans for $200, I found the # CK 15 12 2, so I think it's a '73, outside cases are all good, main shaft & axle's turn smooth + it came with a new starter.

By the numbers on the trans it was built December 15,1972 which makes it for a 1973 model.

Good find.