I just installed a Momo Prototype steering wheel on my '90 C4, using the 7004 boss kit. What I feared most, getting the horn button to work, was no issue at all. However I cannot get the neutral position of the steering wheel quite right. It is either a bit off to the left or to the right. There's just one "tooth" difference on the steering shaft that causes it be offset to the right or left. Suppose the only way to resolve that is have the front re-aligned with steering wheel in locked neutral position?
One more thing, the indicator stalk returns to neutral when taking a right corner but not when taking a left, could that also be related to the neutral position of the steering wheel and hub?

 

1/8 turn counter on one side and 1/8 turn clock on the other (front tie rods) will keep your alignment and move the wheel about 1 degree. Pit lane alignment

 

I had the same problem with the indicator cancel only working one way, it turned out the Momo hub was installed 180 degrees off. This may also explain your mis-alignment?

I hope this helps.

Piglet

 

I had the same issues with the indicators cancelling when I fitted my protptipo. Centering the rack and an alignment sorted this and allowed me to get the wheel straight.

 

Same issue here. Installed a Momo Mod 07 and I'm one tooth away from perfect. Another weird issue is that the wire in the Momo hub has a weird short in it. The horn only works when there is tension on that wire. If it goes slack, the horn won't work.

 

Thanks everyone, the "tooth" is on the correct side, so looking at other replies I suppose it could indeed be resolved by re-alligning..