Steering Boxes: VW vs. TRW; VW Teardown & Rebuild

[OKType3Tim]

As a result of the challenges I had with a new TRW steering box,
http://www.thesamba.com/vw/forum/viewtopic.php?t=659460&highlight=

I decided to dissect a VW type 3 steering box and the troublesome TRW steering box. Various parts of what I learned can be found in different topics over the years. But here it is all in one place:

Here is the Type 3 (311.415.131A) steering box drawing:

And the two disassembled steering boxes laid out for examination:

TRW:

VW:

Now I'll document each component section. Starting with the items across the top of the sections: bolts, gasket, housing:

BOLTS:

VW has qty 4 of M8X20 bolts with spring washers until a change at chassis 3112131805 when they switch to M8X25. Both sizes shown along with the extra flat washer associated with mounting the ground strap.

TRW unit came with qty 4 of M8 X 20 with lock washers instead of spring washers.

GASKET: Both VW and TRW gasket is .2mm Thick. If anyone knows the source for these gaskets, please post.

HOUSING:
At first glance they seem the same, but subtle differences emerge. (And why did they hand grind the casting marks off of the front of the TRW housing? Is this a counterfeit?)

Notice that TRW does not have the alignment points that can be used during manufacturing to assure consistent alignment as the housing progresses through the milling stages:

TRW Inconsistency in milling the saddle/bearing surface where the housing clamps to the beam. VW units have a "step".

Some TRW units have it, some do not.

Alignment for the milled hole where the top end of the steering worm shaft exits the housing is important for proper interference between the worm shaft and the roller shaft. And for proper alignment between the worm shaft and the steering column. I have 5 VW units currently disassembled and they all look like this, with the hole nicely centered in this area of the casting:

The hole in this TRW unit is offset creating a misalignment. This steering box doesn't actually work because this misalignment has the worm shaft jammed so tightly against the roller shaft that you can not operate the unit without excessive force.

I'll break this into a couple posts. Next post, the roller shaft.
_________________
'69 Squareback restoration
'69 Fastback restoration
'66 Type34

[OKType3Tim]

Now to examine the Roller Shaft, the line of parts across the middle row:

From left to right:
The lock nut; both VW AND TRW use the same M10X1 hex nut..

The Steering Gear Case Cover, which externally appear the same.

But internally, VW used a brass bushing, while TRW just has the aluminum of the cover to provide the bearing surface.

It does appear that TRW is using an aluminum material that is stronger than the VW cover material. (BTW, on disassembly, there was only minimal grease up in this bearing surface cavity.)

But the bearing surface is already showing wear just from my attempt to install the unit in my vehicle.

Also, the internal shoulder on the TRW cover is not made exactly the same as the VW unit, such that the TRW cover will not sit down onto the VW housings. (You could file off the small amount of excess material if you were so inclined.)

The lock ring and shim are the same, which means that somewhere there is a source of shims being made.

The adjusting screw is the same, except the TRW is 5mm taller for some reason.

The roller shaft looks to be identical.

Same dimensions.

But as I examined the TRW shaft, I was disappointed to visually see, and then verify with my calipers, that the hole in the top of the shaft was drilled off-center. Not much, but enough that I picked up on it just by looking at it carefully. I checked all 5 of the VW shafts that I have on the bench. All 5 were dead on centered. This means that the top of the shaft is going to bear harder on one side of the cover plate. Probably the source of the wear I noted above.

Bottom SEAL:
The bottom seal is a 24 X 37 X 7. These are readily available online or from your local autoparts or seal store.
_________________
'69 Squareback restoration
'69 Fastback restoration
'66 Type34

[mackaymanx]

[OKType3Tim]

Finally, examine the worm shaft, the line of parts across the bottom row.

From Left to right:
A retainer listed in the parts book as a seal. TRW does not use this.

A seal that is a 16 X 24 X 7. These are readily available online or from your local autoparts or seal store.

A shim that VW places between the housing and upper bearing. TRW does not do this. VW manual calls for this to be typically .35mm. In the units I have tore down right now they vary from .16mm to .26mm. So I don't know the reasoning behind this shim nor the reason for the variance.

Bearings, one for the upper end of the shaft and one for the lower end. Both upper and lower are the same. Here is where it really gets interesting. In the units I have disassembled, I have found FAG 50820A, FAG 508620B, SKF 311120A, SKF 311120AD, and unmarked with cage marking of *C131*. Any unit can have a mix of bearings. These cross to VW part# 411.417.225.
Main Race side:

Reverse Race side:

These are an "Angular Contact Ball Bearing" where one race is provided with the bearing and the opposite race is the actual worm shaft. The VW based units use a metal cage with 13 balls of 5mm diameter.

The TRW bearings do not have any part number markings and use a plastic cage with 11 balls of 5mm diameter.

The harsh reality of a magnified, lighted, camera picture on the TRW cage shows cage cracking/stress, and pitted ball bearings. This on a bearing that hasn't done anything except sit in grease for several years.

The worm shaft initially appears to be the same. And given that the diameter of the balls are the same from VW to TRW, the shaft seems to mate up fine with the older VW bearings.

However, I lined them up for the pictures to verify the they were truly identical:

And found this:

If you just proceed along with installing the TRW steering gear, you will find that your steering wheel is now 90 degrees off from where you thought it was going to be.

And then finally at the bottom of the shaft you have the adjusting screw and lock ring which are identical between the units.

So, I was hopeful when I started disassembly of the TRW, that I would at least get some good spare parts. But not so much:

And this:

_________________
'69 Squareback restoration
'69 Fastback restoration
'66 Type34

[Tram]

Excellent writeup and analysis.

From what you are showing, it's now clear to me exactly how and why these units can just seemingly overnight go loose. The plastic bearing races are a real eye opener, as is the substandard machine work and all the things that are mis- aligned.

The longer adjusting screw just screams "cheat" to me, as it seems only to be longer to make it appear that there is more adjustment to the box than there actually is (as the height of the worm adjuster is a good visual indication of the condition of the box). It also helps explain why the last few boxes I've gotten actually needed this adjustment backed off upon install.

Are these "counterfeit" boxes? Maybe, but if they are, even the parts suppliers seem unaware of it.
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Немає виправдання для війни! Я з Україною.

[Zundfolge1432]

Another sad commentary on the state of aftermarket parts quality. Doesn't surprise me though as folks are now rebuilding original carburetors,fuel pumps,distributors etc because replacement parts are often times junk. I'll be looking for a few spares to put away for myself. Thanks for sharing this Tim.

[Clatter]

Excellent Excellent write up!

Thanks for taking the time to do all of this!
_________________
Bus Motor Build

I have excellent news for the world...
There is no such thing as patina.
It does not exist!

[KTPhil]

...and maybe send a copy to TRW so they know the VW community is on to the cheap corner-cutting. They only et away with it is we don't change our habits and shine a light on it.

Thanks for the teardown and analysis. Maybe this will improve things in the long run!

[wcfvw69]

[ataraxia]

The plastic bearing cages are the first indication that these are garbage. If the bearing cage flexes/fails, the whole box goes to shit real fast.

It also appears that the seals in the TRW box are 'single lip', whereas the VW seals are 'double lip'. That will make a difference in how well the box retains its grease/oil. My leaking / rebuilt steering box had single lip seals and gear oil inside, some of it making it out of the box via the seal.

There are several shims for the bearing race but I'm not 100% sure why they exist - adjustment can be made at the other end of the shaft.

311 415 193
Shim 0.20 mm
for steering worm

311 415 194
Shim 0.25 mm
for steering worm

311 415 195
Shim 0.30 mm
for steering worm

311 415 196
Shim 0.35 mm
for steering worm

311 415 197
Shim 0.40 mm
for steering worm

311 415 198
Shim 0.45 mm
for steering worm

311 415 199
Shim 0.50 mm
for steering worm

It would be great if we could get all of this information in one thread so that we have a resource for rebuilding a proper steering box with the parts sources.

Thanks for documenting what you're doing!

[sjbartnik]

Great thread!
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1965 Volkswagen 1500 Variant S
2000 Kawasaki W650

[KTPhil]

[ataraxia]

[KTPhil]

I'm thinking maybe at the factory they select the proper shim to allow for manufacturing variances.

[OKType3Tim]

Updates and Answers:

Regarding the off center hole in the top of the roller shaft; mackayamanx is correct that, "This should have no effect, as the top of the shaft does not touch anything. .....As long as there is enough clearance around the foot of the adjuster in the recess it will not be a problem." Here is a picture of that clearance.

Good catch ataraxia on the TRW seals being single lip. Double lips seals are available from:
http://www.avxseals.com/Shaft-Oil-Seals-TC24x37x7-p/tc24x37x7.htm

http://www.avxseals.com/Shaft-Oil-Seals-TC16x24x7-p/tc16x24x7.htm
(and maybe other places.)

Regarding the tall "Adjusting Screw": My parts book doesn't show a change. BUT, completing my disassembly of the 5 VW steering boxes I have; I found that the unit that has the tall bolts, also has the tall adjusting screw. Thus, from chassis 311 2131 806 it may be that tall adjusting screws were used:

_________________
'69 Squareback restoration
'69 Fastback restoration
'66 Type34

[OKType3Tim]

[OKType3Tim]

Clatter, where did you find the paper gasket for the lid?
_________________
'69 Squareback restoration
'69 Fastback restoration
'66 Type34

[ataraxia]

Steering box gaskets:

Only if you're absolutely desperate:
http://www.thesamba.com/vw/classifieds/detail.php?id=1618692

Slightly better price:
http://www.thesamba.com/vw/classifieds/detail.php?id=1788940

More reasonable price:
http://www.thesamba.com/vw/classifieds/detail.php?id=1280560

I used to get them out of a source in Germany but it'd all dried up now.

Another seal source:
http://www.oringsandmore.com

Similar pricing but these guys will ship for free once you spend $25 on their website. If not, shipping is $4 so it's no big deal.

[ataraxia]

[W1K1]