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

[ataraxia]

[Chochobeef]

[raygreenwood]

[ataraxia]

Not sure if you noticed this but the top adjusting screw has a shim as well - it's a washer but there are different thicknesses.

311 415 265, shim 2.0 mm for steering roller shaft
311 415 266, shim 2.05mm for steering roller shaft
311 415 267, shim 2.10mm for steering roller shaft
311 415 268, shim 2.15mm for steering roller shaft
311 415 269, shim 2.20mm for steering roller shaft
311 415 270, shim 2.25mm for steering roller shaft

Did you measure the thickness of the washer on the top of the adjusting screw when you took them apart?

This is a testament to the excitement in my life: I read the Type 3 Parts Book on Saturday nights!

[OKType3Tim]

[raygreenwood]

A couple of points of clarification for my mental picture please.

So.....the VW box uses the shim and TRW bkx does not.

So.....does the bearjng outer race seat against a counterbored ledge inside of the housing? I can't tell from the pictures..

If no.......then the only thing keeping the race in place is a combination of the shim and seal.

If yes....does the shim sit on the ledge under the race? It does not appear that it does.

If there is a ledge for the bearing race to sit on.....but the shim is not on that ledge but comes in from the outside.....then the only thing the shim does is provide a seat for the seal.

Also if there is no ledge for the bearing race and the stack up just bearkng race, shim and then seal.....and its only the shim and seal keeping the race from moving outwarr under pressure from the adjustment on the other end......that is part of the reason why the TRW box gets sloppy.

Other item:
I was reading back through this excellent thread......I went back to the polymer cage bearing section. I still stand by my point that polymer cage bearings ard superior (as long as the cage is not old school nylon).........but back when we were talking about the cages....my brain totally skipped over the part about the actual damage to the balls in the bearing.

You note that this box has 0 miles on it or pretty close. That it just spent fives years or so sitting in grease.

That is what sent alarm bells.

The damage you are seeing is consistent with technically...actual corrosion.

This is what is caused when grease/oil becomes acid with age. It does this as a by-product of the sulphides in the oil. They are a sacrificial ion basically.

I have an article from an oil manufacturer somewhere......posted from a site shere others were rebuilding steering boxes and PTO systems on classic tractors and farm equipment. Tbe article explained how the sulphides/sulfur and metals mixes in gear oils and PTO oils work for EP applications.......and how and why they break down and change PH.

This is also where I found out,about the sacrifical copper anodes used in many of these units to combat oil acidity in boxes that are designed to not be serviced for decades.

I'll see if I can find that article. Its also why I have gone to synthetic oil in mine. Ray

[ataraxia]

[Chochobeef]

[OKType3Tim]

Rebuild:
I've decided to rebuild unit #5, the 311.415.131"B" unit. All the measurements are good, and the roller and worm appear to be good.

And I'm going to rebuild unit #3, which is an "A", "+GF+S" unit. The measurements are pretty close to perfect. I'm still considering that I might use the roller and worm from the TRW unit for this one.

Got the major components repainted. 2K epoxy primer and L41 VW Black single stage Acrylic Urethane (PPG Concept DCC paint line).

But, I'm not going to proceed until I have a good shim pack to use. So the focus now has to be on sourcing shims.
_________________
'69 Squareback restoration
'69 Fastback restoration
'66 Type34

[ataraxia]

T34's should have their own drop arms so your box was swapped with a normal T3 box at some point...not entirely surprising!

I'll post up when the parts arrive (2-3 weeks).

[OKType3Tim]

[ataraxia]

[OKType3Tim]

EVALUATION:

I set down with some measuring tools to evaluate the 6 units that I've torn down. I didn't use the electronic calipers much as they tend to have me "Over Measuring", looking for accuracy that isn't actually there.

The parts have been cleaned and sorted:

I obtained these from various sources, so some had steering worm flanges, but not all:

Some had drop arms, but not all:

There are 3 late model drop arms, 1 early model drop arm. Here are the differences; late on the left, early on the right:

Note the markings on the base, "311" vs. "311A"

The main components laid out:

Left to Right:

Note the slight difference in the shape of the main housing casting between the 3 different sources. I think that the markings of "+GF+S" vs. "+W&E" could indicated different OE manufacturers contracted by VW. Maybe someone can provide enlightenment on this regarding whether it means subcontractors, divisions, labor unions, or something else. In any case, the "+GS+F" units come with clearly marked casting dates. (although someone messed up at the foundry and put a year of "19" in the mold on January 22nd.

And, so here are the measurements:

There has been discussion and concern about how to know if the bushings are good or bad. From this sample, I think the spec on the main housing bushing was an I.D. of 23.85 mm. And none of these units show any appreciable wear on this bushing.

I think the spec on the bushing in the cover lid was 23.9 mm. As noted, wear of +.2 will be enough that you can physically detect the side-to-side play of the shaft in the bushing

The spec on both the top and lower bearing surface of the roller shaft appears to be 23.48 mm. (Although the shaft in unit#1 appears to have made it through QA with a bit of out-of-roundness.

And, as noted in a post above, the real wear point is the roller needle bearing, and the roller surface and worm surface interface. This wear dependent on getting the proper "play" set on
1st: the Steering Worm [where the ball bearings are],
2nd: on the top adjusting screw for the roller worm interface,
and 3rd: the axial play on the roller (needle bearing).

.
.
.
AH yes grasshopper--that is what the Bentley manual says!
_________________
'69 Squareback restoration
'69 Fastback restoration
'66 Type34

[KTPhil]

[OKType3Tim]

[ataraxia]

[air-h2o-air]

while this is all great info..isnt the most common wear item the worm gear in the straight ahead position? It gets hammered flat which renders it useless?

[OKType3Tim]

Correct, you only use 1 shim.

But it does affect the cost of producing a shim packet.
_________________
'69 Squareback restoration
'69 Fastback restoration
'66 Type34

[KTPhil]

You only use one shim, right? So it doesn't matter if you throw away 5 or 6 extra shims.

[OKType3Tim]

Correct, they are just spacers used to shift the center point of the worm shaft. This shift is part of the adjustment to make sure that the "free of play range" between the worm and roller, extends equally from turning left, to turning right.

And correct, they do not run against the balls of the bearing.

Pretty sure that they didn't use inch equivalents. But I also think that the thicknesses spec could have been +-.01 mm. My example is that I have a shim that I extracted with practically no damage. It is marked/notched to be a .30 mm shim. But it actually measures .31 mm.

So... maybe US measurement shims are close enough. No lapping required.

And
What if you made the adjustments using a "6-Shim" US set; instead of a "7-Shim" metric set?
_________________
'69 Squareback restoration
'69 Fastback restoration
'66 Type34