915 flange, 944 cv...

[trevorbrady]

grrr!!!

feels like I'm banging my head against a wall!!! This project thing ain't easy (but I suppose if it was, everyone would be doing it!!)

anyway...

I got a 915 box with no flanges, so I got some from somewhere else. Then I got some 944 cv joints and found out that they're not the same pattern. Just won't go.

So... what do you guys with 915 boxes do for output flanges or cvs? (how do you mate one to the other? Can you redrill flanges?)

I've got the narrow aluminium trailing arms btw if that makes any difference.

[boygenius]

I think the 915 drive flanges have use four bolts for attachment and two dowel pins for alignment. I think I read somewhere that you have to drill out two of the CV holes to accept the dowel pins. I think 944 cv joints measure 100mm accross and some porsche 915 trannsmissions use 108mm drive flanges. Not quite sure what year they changed to the bigger CVs. Hope this helps.

[jhelgesen]

Trevor, I've gone through this same thing with my 911 as my 915 didn't come with flanges either.

The 915 flanges are a smaller size than the 944's.

Is your dif fine or course spline inside? Mine is an aluminum case with fine splines from a 79. If yours is a mag case, it should have course splines. If so you can use 901 flanges from a 914 or 901 tranny. Not sure what you can do if they are fine spline.

There is a guy selling 901/914 flanges on ebay for cheap, haven't seen 915 flanges on there.

901/914 flanges have 4 bolts with a pin, you can either put a stud in the cv's or weld and redrill the flanges for another bolt.

[trevorbrady]

jeez... fine splines vs. coarse. I don't know... I seem to remember them being pretty coarse, like only 16 or 17 splines on the shaft.
I have a pic of the splines on my home computer somewhere, I'll post it up tomorrow, maybe you'll know by looking.

I measured up the flanges and the cvs this morning and found that the 944 CV has a pcd of 6x86mm and an outer diameter of 100mm. The flanges in the gearbox have a pcd of 6x94mm and an outer diameter of 110mm. However, only 4 of the holes are drilled through and tapped for the CV bolts.

does this shed any light??

Thanks for your help.

Trev

[trevorbrady]

Originally Posted by jhelgesen

There is a guy selling 901/914 flanges on ebay for cheap, haven't seen 915 flanges on there.

Thanks jhelgesen!! I bought those 901 flanges, they look like they'll fit the bill, and for USD$9.11 plus shipping they'll hardly break the bank to find out.

It does bring to light though the price I paid for the other (wrong) output flanges. I got them used here in Ireland from a Porsche breaker for a whopping €160 (about USD$200) simply because I thought that's what they cost. I won't be so foolish in future...

Pic of the WRONG ones that I already have:



Pic of the ones I bought off ebay (hopefully they're more suitable):