Hello 914 Friends,

I have 3 Topics:
1.) look at the picture and tell me if the red marked part is atteched in the right way?

2.) What is the maximal axial play of the Joint flange if they are tighten up?

3.) after tighten up my Joint flanges they never rotate anymore, what can be the issue here??

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This is out of a /6? This is correct for a 69 and older 911/912 diff. It is set up correctly, but that is a grenade if you don't have the right bolts. The bolts that go into that have little nipples on the tips that stick into the hole in that cross bar and hold it all together. Without those nipples, the cross bar slides right out and the spider gears fly out and BOOM. The 914 style starting in 1970 had the more normal looking flange bolts without the nipples. There is a carrier in the new style with a roll pin that holds the cross bar in place, and holds those couplers (the thing you annotated, which look different on the newer boxes) in place. Check the part number on your trans, and on that diff, and make sure the ring and pinon are matched. If you want, you can either swap in a new style set (needs some machining that I do here and I have sets on hand, usually), or upgrade to a full new style diff. The newer diff has larger spyder gears and is larger in general. The earlier diffs had smaller ring gears, too, but the bolt patter may be the same (I actually never checked, never had to). If you PM me I can check in my parts hoard when I get home and reply here with pics to explain what I am going on about.

To answer your question number 2; axial play on the axle flanges should be about 0.10mm.
Question 3; axle flanges should not be locked to the differential carrier when they are tightened. If they are, something is not not assembled correctly.
The 914 differential shaft is retained with a block and roll pin. The 911 transmission differentials (1967-69) used special flange bolts with projections that stuck into the differential shaft to keep it in place. I'll try to get some picturees together tomorrow.
It would help if you would post some more pictuires of your differential.

Thx Dr Evil,

You already sent me some Parts some years ago. And I did some tranny rebuilds for 914 in the meantime. I also was thinking the diff was assambled in the right way . However the topic with the joint flangs I don't understand. If I put the joint flangs into the diff and tighten the bolts the flangs can not rotated any more. The edge of the join flang is then so hard pressed against the diff housing that rotating isn't possible. I'm not sure if I have the correct joint flangs!? Yes the diff is from an early 914/6 Build in 1970.

I need a pic of your bolts and flanges. The flanges that are supposed to go with that diff usually have a cupped face where the axle gets bolted on. The bolts should be gold in color, and should have the nipples I described. Those nipples line up with the hole in that cross bar. If using newer style bolts, they will be too long, potentially, and will bind on that cross bar. Ill see if I can get a pic from the PET.

This first pic shows the diff diagram from the PET for what you have, the 67-69 older model. Note the flanges, and the bolts, and the lack of a "keeper" pinned to the cross bar. Click to view attachment

This is the 1970 and newer version. See the keeper (#15) and the bolts do not have a nipple.
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Iwill add the pictures tomorrow. The Bolts are gold colored and with the nipples. I will Check the number in the flangs and will post them too.

Then you have a full old set up. Make sure the nipples are in the holes of the cross bar, and also make sure the washer is under the bolt head or you will over tighten and bind everything up.

I will Double Check this! Pictures tomorrow, Thx so far!

the pictures of my diff Setup
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I found this on Ebay, is this how the Joint flang should look like?

You got it. The cupped one is longer. I can shot pics when I get home. I have a set if you need, id just give them to you for the cost of shipping if cheaper than getting local for you. However, that is not the original differential to that box, and your CV axles may not bolt up correctly. The flanges you have are 1970 and newer and are shorter by a little, as you described the binding. Does the number on the pinion head match the one on the ring? the 0.15 is a stock number on all that age, 1604 is the number you want to match.

I think tonight I may just shoot a short video and upload link here so you can see the difference. It wont be cinema gold....but it may clear up some questions for you.

The pinion and shaft were matching, I replaced them with a new set because the shaft was damaged.

You are saying the differential is not the original one but which one is then the correct type.. with the stone in the middle? The service manual shows a similar type of differential I have, is it not the same? The picture doesn't show the joint flanges.

I will take the flanges from you! Maybe you can support me with some additional parts for a rebuild I'm currently working on. If this ok for you I can send you a list on Monday und you can tell me what you get from me for it.

thx for you great support
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If you see the pics I posted, you should have the one with the "stone" in the middle, its part 15 on the second pic. It has different parts inside, but I have a modified set of parts that you can retrofit into your current diff if you like. That may help with the flange issue, too. I can assemble the same thing here and see if the specs work out. Last night was a no go as I went to pick up some other flanges at a machinist friend of mine and we caught up for a few hours and my night disappeared. Ill still try to get pics at least with some explanation as this topic is frequently bought up to me and this is a good place to put some concise info.

That pinion was definitely toast.

I think the best solution would be to update to the differential with the stone in the middle. Therefore I would need a differential and the joint flanges. The current joint flanges I have are modified to fit the 69 differential.
For an other rebuild I would need a shaft and a pinion... Dr Evil, do you have these parts to support me ??

I have all of the parts you need, and already modified to fit. Light and easy to ship. Lighter than the flanges, so you can keep those if you like as long as the measurements work out. I have pics on my phone, for you but no service inside my office building. More info to come! Just PM me for the parts.

Ok, finally got a chance to download and process the pics. As you can see, the newer diff is larger, the parts are different as the puck like pieces need to fit into the "stone" as you call it. To make all of the newer bits fit into the smaller old diff, the pucks need to be turned down a bit.

Thx for the pictures, now it is clear for me
Have you got my E-Mail ?
During winter period I will solve this topic on my 914-6 transmission.