TheSamba.com :: View topic - Building a strong gearbox with 95% OEM parts

Tue Jul 12, 2022 4:12 am

Clatter wrote: benozoval56 wrote: Clatter wrote: This is a great thread.

Next is for the details of doing all this,
And it'll get long and off-track for sure! :D

Like,
What drill bits are hard enough to drill holes in the hubs?

what size holes am I drilling here please?

ngobet wrote:
Drill 3mm holes in the hub. .

Just have to read the thead.. :wink:

have read too many times and still missed it :lol: :lol:

Tue Jul 12, 2022 6:40 am

benozoval56 wrote: Clatter wrote: benozoval56 wrote: Clatter wrote: This is a great thread.

Next is for the details of doing all this,
And it'll get long and off-track for sure! :D

Like,
What drill bits are hard enough to drill holes in the hubs?

what size holes am I drilling here please?

ngobet wrote:
Drill 3mm holes in the hub. .

Just have to read the thead.. :wink:

have read too many times and still missed it :lol: :lol:

Carbide bits will drill holes in hardened trans parts. Be aware that they aren't cheap, and are somewhat fragile.

A lot of trans parts are surface hardened to a depth of .030"- .040". The gears are softer, inside, but if you're drilling all the way through be careful when hitting the hardened material on the other side. When you break through the surface, if you're too aggressive you'll break the bit. Up here carbide bits are expensive. I've broken 2 1/8" ($20 each) and 1 1/4" bit (over $50- guess how loud I yelled when I broke that 1!). The shift forks weren't especially hard, but thought I'd post that pic to show what's possible...

Fri Jul 15, 2022 3:27 am

YOu people certainly have too much time on your hands. :lol:

I once saw a flywheel w/ several dozens drill holes in it. Maybe improve the performance of pistons by drilling right thru the top of it? :lol:

Sat Jul 30, 2022 7:58 pm

ngobet wrote: Let's move to end play....

The dark circlip is the 002 version, thinner than the 091. On this picture, you can see that the hub was machined to position it correctly.

The next picture is after removing the circlip, when the hub is push against the front 091 circlip (top). When machining the hub, measure the difference of thickness of the circlip (usually 002 is 1.49mm, 091 is 2.47mm). 4th gear will have around 0.25mm play and 3rd 0.50mm play (see...). You will then machine around 0.80mm off the hub (MEASURE YOURSELF ON YOUR PARTS) to split the endplay between the 2 gears, and both gears will end with 0.37mm.

Now all your idler gears are well oiled and have sufficient endplay.

Don't do the handpacking of the needle bearing as suggested by Berg. It brings too much heat in the gear. Look for the early caged needle bearing, there is more room for oil.

my 3rd/4th gear slider has a groove on the "teeth" and I cannot remember which way it came off the shaft. Is there a diagram that shows which way this should be installed please?

Sat Jul 30, 2022 9:02 pm

Looks like you are going far from the reservation. :lol: Maybe you are one of those who just wakes up one day and be good at transmissions. YOu may want to slowdown cutting stuff. Bernie Bergman did many things to the VW engines. -just saying.

I started out sticking exactly to the Bentley manual when I built my first trans and used that for years -put me thru school. Then somewhere along there, I built many more for others. Since I have had my machines I did more mods required in drags and learned a bit more on what not to do on the parts.

If this is gonna be your trans, so be it - modify as much as you want. But I sure hope you will not do these to customers' trans if you ever decide to do them for money.

But I am truly enjoying myself watching this thread.

Sun Apr 02, 2023 1:20 am

Quick question on the Super Diff.

Can 10T spiders and 15T side gears be used without ant further modifications required?

Sun Apr 02, 2023 8:26 pm

Most that use the 15/10 tooth combo gears in a swing axle diff are using two spider gears in an oem housing. If you want a super diff, you’re going to have to find a NLA used/nos one specifically made for the 15/10 tooth gears. All of the modern new commonly available super diffs are made for the more common 17/11 combos, and the 15/10 gears will not mesh properly with 4 spider gears.

Thu Aug 24, 2023 7:39 am

What kind of power numbers should this be able to handle? I'm not sure what exactly I want to build yet but I know it will be close to 2.0L and turbo charged. Is this something that would be worth my time or should I just but another unit?

Mon Sep 18, 2023 6:32 am

Mon Sep 18, 2023 10:01 pm

rustybug1990 wrote: What kind of power numbers should this be able to handle? I'm not sure what exactly I want to build yet but I know it will be close to 2.0L and turbo charged. Is this something that would be worth my time or should I just but another unit?

It's more to do with the severity of your launches that will break any "built gearbox" as opposed to how much HP you are producing

Tue Sep 19, 2023 12:03 pm

So any idea what kind of launching punishment could this handle?

Tue Sep 19, 2023 3:26 pm

How long is a fish?

I’d say a transaxle built like shown here could pretty much handle anything you could throw at it if you’re running street radials.

If you’ve got slicks and are hitting the water box and doing a burnout at the strip,
Then you might be pushing your luck.

Or if you’re on the throttle bouncing off the rev limiter while airborne in a desert car..

Tue Sep 19, 2023 6:26 pm

Thank you very much, put just how I can understand it.

Thu Nov 16, 2023 9:25 am

I've got a few questions about using a Type 1 or Type 3 IRS transmission to build for a split window bus (61-67 tunnel mount unit). This thread seemed like a good place to ask.

No lowering, stock height with reduction boxes.

I've got a few transmissions that I may decide to use as a core to rebuild for this bus.
I have:

Type 3 IRS
Type 1 IRS
Type 3 swing axle

Are any of these units good to use as a base for a stock height bus?

Sat Nov 18, 2023 11:37 am

StockNazi wrote: I've got a few questions about using a Type 1 or Type 3 IRS transmission to build for a split window bus (61-67 tunnel mount unit). This thread seemed like a good place to ask.

No lowering, stock height with reduction boxes.

I've got a few transmissions that I may decide to use as a core to rebuild for this bus.
I have:

Type 3 IRS
Type 1 IRS
Type 3 swing axle

Are any of these units good to use as a base for a stock height bus?

There are many variables to your equation. You need to define what your wanting gear ratio wise with the reduction boxes for your Bus, and what years the Type 1-3 transaxles are from.

The early Bus transaxles had 1-4 ratios of 3.80/2.06/1.22/.82, 4.12 r&p with 1.39 reduction boxes. The later had 3.80/2.06/1.26/.82, 4.37 r&p with a 1.26 reduction box. All of the pre-68 Bus transaxles used thicker coarse tooth gears. The early 4.12 pinion shafts used the securing nut on the end with a keyed 4th, while the later 4.37 ones used a circle clip and a splined 4th.

Your Type 3 transaxles will have 4.12 r&p’s, and most commonly 3.80/2.06/1.26/.89 gear sets. The earlier used 1.32 3rds. I haven’t taken apart that many type 3 specific transaxles, but all I’ve seen had a 3.80 1st with the coarse tooth 3-4 gear sets. Pretty sure the late ones never got 3.78 1st’s, or the fine tooth gears. Early pinion shafts will have a keyed 4th, while later will be splined.

The Type 1 trans is most commonly a 4.12 keyed/splined r&p or a splined 3.88 r&p. The early cases were numbered, but the later 4.12’s had an AH prefix, and the 3.88’s an AT. The other less common ones would have an AV for a 4.12, or an AM for a 4.37. It could have coarse, or fine tooth gears with a 3.80, or 3.78 1st with an .89, or .93 4th.

See what you can find out with the serial numbers from the cores. You can look through the oil filler hole to see if the 3rd gear has coarse, or fine teeth.

Tue Mar 26, 2024 8:14 am

This is real good stuff, i just finished my new motor and the gearbox in the car has a bad 3rd synchro and someone i think swapped 4.375 into it (early IRS) and it revs like 3200 at 60 with a 205 65 15; I just scored a late single cover IRS with 3.88s in it and this is going to help address any concerns that that one might have; Question for OP though, what is the difference in an IRS ring/pinion setup compared to the swingaxle fixes you did? ie the spider gears, is there such a thing as 15 and 10 spiders for an IRS??? or are we stuck with 11 tooth spiders? Can older spiders be made to work or are they a different creature?