E28 Boss Fitting on an E21?

[Eddie.]

Does anyone know if the E28 fine spline is the same as the E21 version?

I've seen a steering wheel boss that's listed as for an E28 with a fine spline, and I was wondering if it could be used on the E21 as a straight fit.

[Duracel79]

Hi Eddie,

I can probably try at the weekend for you. I have a MOMO fine spline boss from my E24 (E28 based) which I could try on the E21.
I am led to believe they will fit.

Ben

[Eddie.]

Thanks for the offer but I don't have my car nearby at the moment, it's about two hours away at my dads stored up for winter. I might just take a gamble on the boss if it's thought the E28 fine spline will fit, I'll give it a go.

[Duracel79]

misunderstanding here, I meant I can try it on my E21 and let you know if it fits, probably tomorrow. I'll take some pics of the mounting sides etc.
Ben

[Eddie.]

Ahhhhh sorry, yeah that would be really helpful, thanks very much!

[Duracel79]

Well its good news with some bad.

The E24/E28 boss will fit on the E21 steering column. The spline is correct and it will bolt down fine. The issue is the boss doesn't contact the indicator canceller.
Looking closely at the two columns you can see the E21 has twice the length of splines. When fitting the E24/E28 boss to the E21 column there is a gap left behind the wheel of about 5 to 10mm.

E21 Column:


E24/E28 column:


E21 MOMO Boss:



E24/E28 MOMO boss C2005:



Just for extra reference this is a standard E24 wheel:



HTH

Ben

[Eddie.]

That's great, thanks so essentially I would need to extend the tab that cancels the indicator, in order for it to contact the required point?

[Duracel79]

That's great, thanks so essentially I would need to extend the tab that cancels the indicator, in order for it to contact the required point?

Yes that and live with the boss having a bigger than normal gap behind it and the column (cowling).

Ben

[nas80]

Remove that bearing and put on the other side of the boss with a thick washer. Then it will work.