IRS drive shaft install

[mladen]

I'm trying to install my drive shaft, without much luck. I have IRS and TKX transmission, 31 spleen shaft from FFR.

I read quite a few threads and tried mentioned suggestions, like adding some lubricant to the spleen, angling the shaft to the driver side (the build manual suggests to have it above the center section but that just seems to make the angles worse), I looked for the rubber donut, and aside the orange cap, there doesn't seem to be anything else. Also, the transmission is already jacked up by 3/4", which is almost as much as it can go before hitting the trans tunnel cross brace.

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[mladen]

I have tried removing the spacers so the rear end of the transmission is lowered. It did help a bit where I could get maybe 1/4 to 1/2 of the shaft to engage, but then the rear yoke gets stuck against the diff. I tried litghtly tapping it with a deadblow hammer, but didn't help much, and I'm not comfortable putting any significant force into it.

[egchewy79]

driveshaft needs to go in straight. you may need to unbolt the engine/trans mounts and use a prybar to pull the tail of the trans enough to get the shaft in. good luck.

[mladen]

driveshaft needs to go in straight. you may need to unbolt the engine/trans mounts and use a prybar to pull the tail of the trans enough to get the shaft in. good luck.

I might be missing something because I'm on my back when trying to install it, but I'm not seeing an option to get it straight. I've unbolted the transmission and tried with it at the lowest where it's lying on the round crossmember as well as its highest when it butts up against the tunnel crossmember. Still no luck

[edwardb]

It's not going to go in unless dead straight. Your pictures aren't close. Don't even think about hitting it with any hammer. When it's right, it will slide right in with very little resistance. Beating on it will only damage something and it's still not going to go in. My Mk4 with IRS I was able to position the driveshaft so that it was straight and went right in. Can't explain why yours isn't doing the same. But, from the pictures anyway, looks like you're going to need to loosen and move some things to get that straight-in shot. That's assuming you have the right length driveshaft.

[rich grsc]

I literally just came in from installing mine. Now, granted mine is the older IRS, but there is no way it will go in from under the differential. The driveshaft had to be above the differential on the passenger side, used a pry bar and lifted the transmission maybe 1/2", went right in. Took maybe 15 minutes.

[mladen]

Good question on the length. This is supposed to be 16038 – 31 Spline 2015 IRS 8.75”

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I did manage to raise the transmission beyond the crossbar by moving it to the side and try to approach it with the shaft above the diff on the driver's side, but could not align side to side. I can try the passenger side, but the diff on that side is a lot closer to the frame and I'm not sure the drive shaft would even fit through. Happy to try any option before I pull the engine partially out again. It took me hours to align the tabs properly.

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[Tooth]

This is one of those wonky things where some drop right in and others are a pita. Mine went right in, then realized they sent me the wrong drive shaft. That was nearly a month and a handful of emails ago, and I'm still waiting on FFR to send me the correct one. At least I've seen enough of these threads to expect it may not line right up.

[rich grsc]

Good question on the length. This is supposed to be 16038 – 31 Spline 2015 IRS 8.75”

I did manage to raise the transmission beyond the crossbar by moving it to the side and try to approach it with the shaft above the diff on the driver's side, but could not align side to side. I can try the passenger side, but the diff on that side is a lot closer to the frame and I'm not sure the drive shaft would even fit through. Happy to try any option before I pull the engine partially out again. It took me hours to align the tabs properly.


It should be easier from the passenger side, as the transmission is offset to that side.

[mladen]

It should be easier from the passenger side, as the transmission is offset to that side.

No luck with that either. The diff is much closer to the frame of the tunnel on that side and the shaft can't go through to get beside or above the diff.

If I lift the engine again that might increase the downward angle of the transmission output. But really trying to avoid that. I assume I'd need new nuts for the engine mount as well, they didn't go on easily so I assume they were deformed thread nuts.

[mladen]

Ok, I managed to get it solved with the help of ChatGPT again. Nah, just kidding, I lifted the engine out and got enough downward angle on the rear of the transmission that the drive shaft just slid over. I'm off to the store to buy new engine mount nuts though.

[Tooth]

Glad you got it in, and glad I didn't put the nuts on my engine mounts yet. :cool:

[John.Gallegos415]

I had the same problem. I noticed when I dropped in engine and tranny that the end of the tranny had some "wiggle" room and I could move it an inch or so side to side. That of course helped when installing the transmission mounting bolts. Then later when installing the driveshaft, I realized that my angle was off. I removed the transmission mounting bolts, moved the transmission end over about an inch towards the drivers side, followed the recommendations about the position of the driveshaft, and was able to get it installed with minimal effort. I had to rotate spline by spline and after about 3 tries, it slipped right in.