Building a strong gearbox with 95% OEM parts

[ngobet]

After breaking a few pro-street and such gearboxes and reading many threads on the internet about VW gearboxes, I have to say that It is possible to build a really strong transmission using 95% VW parts, 10% aftermarket parts and a few mods.

So here is a guide to help people willing to build a strong gearbox, addressing those main concern:

weak 1st gear
idler gears end play
differential strength
keep ring and pinion in place

First, you want to use the most recent gearbox you can find, they got improved a lot by the factory. Here, everything will mostly be an early 72 AT gearbox. Buy the Bentley manual about the gearbox you will be modifying. After disassembly, you should understand the terminology for each part and end up seeing this:

The mainshaft is in the top of the picture and it is the early version. I will start by swapping this to use the "superbeetle" mainshaft, which actually came in every gearbox from around mid 73. At least in Europe. This superbeetle mainshaft carries 9 teeth for the first gear and the consequence is that each tooth is wider and stronger. 1st has a ratio of 3.78 instead of 3.80.

To do this swap, you need the superbeetle mainshaft, including first gear idler and second gear idler. Then you have to decide which 3rd and 4th gear to use. Beetle gearboxes use either the early 113 style gears or the 002 gears.

Here is a picture to see the difference. Left is a 002 idler gear, middle is a 113 gear as well as on the right, where you see a 113 idler with synchro cone removed. The 002 gears are the factory evolution for 113 gears. The synchro cone is brazed on the gear at the factory. 002 gears have a recess under the cone where they touch the slider hub and carry 3 notches to improve the lubrification.

Here is a close-up. The red arrow on the right is pointing to the recess.

Since the slider hub on the superbeetle mainshaft is splined instead of keyed, you can modify the 113 gears to use them or stick to the 002 gears which came in the gearbox with the superbeetle mainshaft. (The other option would be to modify the mainshaft to use a woodruf key, but I don't like this because splined is superior).

Right side you see the keyed slider hub and splined on the left.

Weddle manufacture a washer to modify the 113 gears. You will have to separate the synchro cone, remove the original washer and replace it with the weddle one (thicker) and press the synchro cone on the gear. Then, as for every 113 style idler gear, you will have to tig weld the synchro cone to the gear. Weddle provides detailed instruction when you order the washer.

On the left you see a disassembled 113 gear. The 113 gear in the middle has the thicker weddle washer ant the right one is a 002 style.

Then, you should tig weld the synchro cone

and then machine the inside to clear the hub. The slider hub also has to be machined.

However, for this particular gearbox, which was for my convertible, I decided to use 002 gears with fine teeth, because they run quieter. They don't break because of the torque but rather because you break something else in the gearbox and debris get in the gear, ending up breaking the fine teeth. I have around 230nm of torque in this car, not too agressive driving.


For the differential, my order of preference is: 11t/17t oem diff (that is 11 teeth on the spider gears, 17 on the side gears) < 4 spider gears 11t/17t super diff < 10t/15t oem diff < Quaife torque biaising diff. This is what we have easily available in europe. I don't really like the super diff because most of the time, the torque ends up being split between 3 spider gears (at most) and they have poor oiling. The earlier 10 teeth/ 15 teeth differential is really impressive after a few modifications. And the quaife is always good, after all Audi Quattro started winning in group B 30 years ago because of it.

This is the 10 teeth / 15 teeth sidegears internal for swingaxle gearbox

So if you decide to use a 10t/15t diff, you need to modify it to take 2 snap rings to keep the side gears. This modification is already made on the superdif. Buy 4 new snap rings.
Start by taking the thiner sidegear thrust washer that you have and measure with a single snap ring how much play you have by prying on the sidegear from the inside of the diff.

Using this measured play and the thickness from the second snap ring, you can machine the groove in the diff to meet the specification from the bentley.

Then do the other side and you have the strongest non-locking diff for vw beetle

[Chickensoup]

Amazing write up sir! Bravo
_________________
-'85 c10 5.3 LS, 222 cam, long tubes, x pipe, 3 inch spin tech's
-'05 B5.5 TDI Wagon 17in sport rims ;EGR + BSM + ASV Delete, Stage-2 Tune, straight pipe
'65 Tourist Delivery Build
'66 RIP
'69 RIP
Hosea 4:6 "My people are destroyed for lack of knowledge"

[Lingwendil]

Transaxles have always been voodoo/black art to me, but one of these days I want to tackle one. Very clear description and nice pics!
_________________
73 super beetle thread http://www.thesamba.com/vw/forum/viewtopic.php?t=649622 Back on the Road!

Modify your Kadrons for SVDA http://www.thesamba.com/vw/forum/viewtopic.php?p=8115884#8115884

Cast iron VJU4BR8 SVDA reference thread- https://www.thesamba.com/vw/forum/viewtopic.php?t=...mp;start=0

Need replacement filters for original Kadron aircleaners? WIX #42087 is a perfect fit, as is Napa Gold #2087!

[Ohio Tom]

a few things to add:

1. there is another option to put 113 gears on a late model main shaft.
You can cut the hub down and bore the gear out to provide clearance needed.
I have a stack of cut down hubs just for that purpose.

2. A few spot welds on the gear is not enough for any real HP. It will break the welds you have pictured.

3. I like to weld up the whole thing and then grind it back down to get the proper thrust measurement. Taking care not to overheat and distort the whole thing. ONce done, you will likely have to hone the bore so it will fit on the idler bearing.

4. 95% + 10% = 105%.. LOL..


5. The 10/15 tooth combination is stronger.

Not sure why you think super diff's don't load all the spider gears?
Most quality superdiffs do just fine and make it much stronger.
I do add oil holes to keep them lubed up for one wheel burnouts..

[Ohio Tom]

Also, to swap to a late model mainshaft (splined) you need a different intermediate housing bearing. And maybe the whole housing...
The shaft diameter is different. They make an adaptor bearing, but many times the housing takes a flanged bearing and an adaptor bearing is just not available for the splined mainshaft.

Mcmscott can verify my sentiments...
Or attack me..
Either one...

[ngobet]

Let's move to end play. First you need to improve lubrification on the thrust surface of the 1st/ 2nd idler gear. This is the only performance mod from the blue gene berg book that you want to make.
Drill 3mm holes in the hub. The material is very hard, I use a short centering drill bit and then cut the hole. That will bring oil to the other side.

When this is done, mount idler gears without synchros and the hub on the pinion shaft. Mount the pinion shaft in a press and use 3rd gear to push down on the stack. Measure the end play on each gear and adjust to reach 0.15mm of play (0.006). First gear is adjusted with a washer and second with different thickness of snap ring. You don't wanna run a lower end play. Don't bother removing the adjustment washer and maching the hub and gear to reach the desired endplay.

3rd and 4th don't have an adjustment from the factory. However, since the new splined slider hub (to match the superbeetle mainshaft) is secured axially only by 2 circlips, it can move on the mainshaft. The consequence is that the 4th gear always ends up with a tighter end play than the 3rd, because torque pushes the hub towards the front of the gearbox.

There is a trick to fix that using 091 circlips, which are thicker. By consequence, you need to machine the hub to clear them, but you can decide where it stops on the 4th gear side.

Start by mounting the hub and gears on the mainshaft. Push the hub towards the front circlip. Measure how much total play you have on 3rd and 4th.

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.

[nsracing]

I like it!

[Casting Timmy]

Nice write up on it all.

On first and second I usually go for .010" and then .008" clearance as first gear has a tendency to burn up without enough clearance.

I also like to clip third on the pinion shaft as tight as I can, it keeps the shims and other parts from getting hammered and losing end clearance on those gears. Seen some really bad local boxes where even the small pinion nut was bashed and had damage, 1st gear was mushroomed so bad I threw the rest of the shaft away.

I do like your use of fine tooth gears, besides being quieter they are more efficient. Used those in a couple light car applications with stock motors so they could keep a hair more of that tiny power going to the wheels.
_________________
T1 IRS Rebuild Book on Lulu.com
http://www.lulu.com/shop/tim-marshall/t1-irs-transaxle-book/paperback/product-24055997.html
As seen in Volks America Issue 14 Page 11 (Full page review)

[ngobet]

thanks for the comments.

Is it useful for the others? is it too detailed? or maybe difficult to see what I am doing?

[Lingwendil]

Whatever you do, don't stop!

I love these sorts of posts.
_________________
73 super beetle thread http://www.thesamba.com/vw/forum/viewtopic.php?t=649622 Back on the Road!

Modify your Kadrons for SVDA http://www.thesamba.com/vw/forum/viewtopic.php?p=8115884#8115884

Cast iron VJU4BR8 SVDA reference thread- https://www.thesamba.com/vw/forum/viewtopic.php?t=...mp;start=0

Need replacement filters for original Kadron aircleaners? WIX #42087 is a perfect fit, as is Napa Gold #2087!

[jfdestree]

[ngobet]

ok nice to read!

Let's move on to the case. The later ones, with the single large nut to hold the pinion bearing, are more rigid in my opinion. Here on the picture with a chromoly pinion nut from Weddle.

You want to use ONE billet sidecover on the left side. Weddle has a very high quality one.
The bentley has all the information to set the ring and pinion, make sure you understand everything before getting started. This is one of those things that takes some thinking. and you will need to source or build a bunch of tools. Bearing preload should be set to .010". Backlash should be set between .030" and .060", the first for track and later the number you want for street and durability.

After doing this, you should check the pattern. In Europe, I buy "Tuschierpaste blau" off ebay to do this. It isn't described in the bentley, but do it, there is no harm in double checking.

For swingaxle gearboxes, you will also need flange stiffeners. These are the thick black plates behind the 6 nuts holding the axle tubes.

The problem with swingaxle gearboxes is that you cannot buy some parts in new. This is the case for fulcrum plates, which vary a lot in size. I keep as many as I can, measure them for wear (uneven thickness) and to sort them. You will break drive axle if there is too much play there.

With the 10t/15t diff, you can break stock axles further.

Having switched to the later intermediate housing to accommodate the superbeetle mainshaft, we need to install a steel thrust plate for the mainshaft bearing. Otherwise it pounds into the case.
This is the yellow plated plate in the front of the gearbox.

Let's machine 1mm off the nose to compensate for the thickness of the plate.

You should also make sure that the 1-2 and 3-4 shifting forks don't have any play. This is mandatory to have smooth shifting. Reverse is usually ok because it is guided by a longer bore. Machine some bushings and press them in there to fix any play.

Also make sure that you take care the clutch shaft. Either buy the HD version, or weld the original one. From the factory it only has 2 spot weld on the ends and they break,

[Casting Timmy]

Might double check your numbers on backlash.....030” and .060” is way too much. I do a minimum backlash of .006”, but most of the time start used ring and pinions off at .007-.008” to see how they pattern. I try to make it match the pattern it was running before most of the time.

You might check GM’s gear marking compound out. Weddle sells it in baby tubes or you can get some offline. It’s nice in that you can leave it on as it dissolves in use.

Nice write up. My guess is your more used to metric and missed a zero.
_________________
T1 IRS Rebuild Book on Lulu.com
http://www.lulu.com/shop/tim-marshall/t1-irs-transaxle-book/paperback/product-24055997.html
As seen in Volks America Issue 14 Page 11 (Full page review)

[Chickensoup]

stop it!!!! your making me want to get my mill back up and running

no really tho, keep posting! and thank you for taking the time to write all this up. let the novice transmission builders multiply
_________________
-'85 c10 5.3 LS, 222 cam, long tubes, x pipe, 3 inch spin tech's
-'05 B5.5 TDI Wagon 17in sport rims ;EGR + BSM + ASV Delete, Stage-2 Tune, straight pipe
'65 Tourist Delivery Build
'66 RIP
'69 RIP
Hosea 4:6 "My people are destroyed for lack of knowledge"

[ngobet]

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Very nice write up. I did a similar build a couple years ago with the difference of an 091 1st idler, 1.35 3rd, 0.89 4th, and a Super Diff. Which axles did you end up going with?

[Albertoprop17]

How many holes do you drill into the 1st/2nd hub?

Which is better, 113 style 3rd/4th with welded synchro cone or 002 style ones?

It will be very cool to see some videos of how do you set the end play of the gears in the shafts, I'm not able to imagine it yet (I've never dissasembled a gearbox)

How much torque will the gearbox hold with these mods?
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[ngobet]

[ngobet]

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