Steering Knuckle Quandary

[Mark S]

Long story, but I needed to replace my right-hand steering knuckle as the thread was stripped on the stub axle. Bus is an '87 RWD without power-steering. It has got the later single-piston, floating caliper front brakes and I believe the disc size is 258 x 16mm.

After some research, I found that the VW Part No I needed was 251-407-312-AG. This replaced the earlier version, ... AE, from '86 onwards. The key differences between these parts I found after some research to be:

1. The AE is 19 mm in diameter at the outer bearing while the AG is 22 mm.
2. The AE has threaded caliper mounting holes while the AG's are smooth, reflecting the change from fixed to floating calipers in '86. The latter is supposed to accommodate M16 bolts, I'm told. I don't know what size bolts are used to mount the earlier calipers (but one of you good people probably does).

The knackered part that I was replacing matched the above description of the AG and was indeed stamped '251 AG'.

I ordered an AG from eBay described as new and unused. When it arrived it was noticed that the caliper holes were smaller than on my old one (M14, possibly), and they were threaded. The casting around the holes was also subtly different. The spacing of the hole centres, however, seemed to be the same. The part was stamped identically to my old one, front and rear. It had what looked like a pukka VW logo embossed on it, and the outer bearing diameter was 22 mm as expected. The seller is adamant that it is a genuine VW part and the number he stated is correct. He tells me he has been on ETKA trying to get to the bottom of it and is flummoxed. I suggested it might be a factory reject or mis-stamped but he said he has never come across such a horror in his 30 years of selling VW parts, etc. Fair play, he has agreed that I can return it.

As this replacement clearly would not accept my calipers, I ordered a second replacement with the same part number from another supplier. This one arrived, was identical to my old one and went on perfectly.

My bus is back on the road but I have got the problem of identifying the oddball in the hope of finding a home for it.

SO DOES ANYBODY KNOW...

- whether there is a steering knuckle stamped '251 AG' with a 22 mm outer bearing diameter and threaded M14 (ish) caliper mountings;
- and, if so, which model it is supposed to fit?

If anyone actually needs such a part and would like to make me an offer for it, that would be even better and save me the trouble of returning it! It could probably be machined into the right configuration quite easily, but obviously it would be better to use it with the model it was made for.

[jamesc76]

Im a mechanic and whats a steering knuckle???

[Mark S]

One o' they: http://www.ebay.co.uk/itm/160605890844" onclick="window.open(this.href);return false;

[mm289]

Stub axle to you and me James, VW call them steering knuckle

MM

[jamesc76]

Stub axle to you and me James, VW call them steering knuckle

MM

so the rest of the world call it stub axle vw steering knuckle , sounds very yank to me!!!! Oh well everyday is a school day!

[Mark S]

Well done, chaps! Good to see we've got the A-Team hard at it on this one. Now we've agreed what a steering knuckle is, can anyone provide any clues that might help answer the question?

Basically, why has the shiny black one got smaller holes than the rusty brown one when they display the same Part Number?

[icosahedron]

Well, I have an early van ('83) and mine look like the brown one. Holes definitely not threaded and a slight difference in size between the two. ETKA part number for mine is 251 407 311 AE.

[Mark S]

Thanks, that's good info. I believe the 311 is for the left side and 312 for the right. From what I have learned recently, AE would be correct for your model year. Does it actually have 'AE' stamped on it anywhere?

I am surprised that yours is not threaded, though: I was told that the AE was because the calipers bolted into it. If neither version (AE or AG) is threaded it seems even more odd that my new one is. The plot thickens...