AW70 to M47 driveshaft issues - 240 edition

[Alan29]

So I'm in the final stages of the AW70 to M47 swap on my 1993 240 and I'm running into an issue getting the two piece shaft back together. I am using the 1993 AW70 rear with the M47 front that came with my M47 parts. Both of the AW70 halves separated like they should without any fuss. Joining the M47 front to the AW70 rear is giving me extreme grief. I located the alignment arrows. I have verified there is no weird obvious spline differences. Both halves are meshed together but it won't go in by hand.

After reading they can sometimes be a little difficult to join I stand the AW70 on end and use the magic of gravity to tap the top portion into the splines. Its taking way too much force. Part of me thinks I should just smash it it all the way, but the better half of me knows this won't be sliding like it should if I do that. I return it to my work bench and after some swearing and smacking I get the two halves separated again. This is what I find:

So me forcing it caused some gouging of some kind of plastic/epoxy coating with one rib completely flaking off. It seems like this coating is preventing me from sliding the M47 half onto this.

I've searched and I can't find much of anything about this coating. Was this certain model years only? Any ideas or words of advice?

 

[DET17]

I've searched and I can't find much of anything about this coating.

There was a thread in MAINT maybe a year ago, discussing this. I think K-Jets had the 411 on it.... something that the late model RWD's got. Another fellow had the same issue.... I think now it might have been @lookforjoe ? Not 100% on that but the issue for sure was discussed.

 

[Jack]

Can you post a video of how you’re applying the lube ?

 

[Alan29]

Can you post a video of how you’re applying the lube ?

I guess but I was hoping I could do it via FaceTime so we can lock eyes during application.

 

[towerymt]

I would clean off all the grease from both sides and try dragging a hook through the grooves and see if you catch anything. Get both sides completely clean & dry and see if they fit together.

I would probably try rotating one half relative to the other by one groove (so, misaligned) and see if it goes together.

I would try isolating if/when it goes smoothly and when it doesn't. Sounds like maybe it just won't go...but that's where I would start.

I've never mixed driveshaft sections before, so I'm not sure. I assume you don't have the M47 back half.

 

[Alan29]

Thanks I'll give that more of a shot after cleaning it and knocking down some high spots where it might catch. We've tried rotating one cog at a time last weekend and couldn't get it to fit at all...which is why I got a little more aggressive today.

 

[lookforjoe]

That coating is to prevent slop in the splines. The shafts are keyed - they can only go together one way. That doesn't mean that the splines from another driveshaft (potentially different manufacturers) will fit

The one I have with the blue coating is a spicer (Type 13). It will not fit in a Type 03

There is a buildup in the keyed slot that is not supposed to be removed or forced into an open slot

 

[Alan29]

Strangely my aw70 front has one missing spline but it's not that way on the m47 front. It looks like the part of the coating that peeled off might have been higher than the other slots corresponding with the other side. I didn't notice that until I started this ordeal.

 

[tjanson]

I don't have any keying on my '89 vintage M47 driveshaft.

The "blue stuff" is called Glidecoat. From what I can tell from googling, you can't repair or replace it.

 

[lookforjoe]

I think you best bet is to get an M47 rear section - probably not what you wanted to hear
Typically the manual driveshafts have a larger diameter rear tube anyway.. did you compare the u-joint sizes between the two shafts you have?

 

[shoestring]

I just looked through the GCP catalogs and all the rear slip yokes are the same pn, 1340500, from 85-up, manual and automatic for 240. -> 84 use different pns, but that looks like it's due to different u-joint sizes than 85->.

I assume this is the M47II stuff we sold you. The car we used it in is a '93, originally an AW70 car. I'm nearly 100% certain the car the M47 front half came out of was an '88 245. I don't have any input on what might be wrong here, but I wouldn't jam it in there, it'll never slip properly.

We've mixed and matched prop shafts a jillion times over the years and never had a problem. I guess there's the outside chance that we've just been lucky all this time, but I find that unlikely. We've never had a 740, and the only 940 is Cam's with the M90.

Again, I don't know. I'd love to know the answer but not as much as you would.

 

[Alan29]

I think you best bet is to get an M47 rear section - probably not what you wanted to hear
Typically the manual driveshafts have a larger diameter rear tube anyway.. did you compare the u-joint sizes between the two shafts you have?

Yeah probably right. My other option is having a shop modify my aw70 front for the m47... although I don't even want to know what they'd want to charge for it.

There are no ujoints to compare on the m47 half...it's a straight shaft with the three bolt flange to the trans with guibo. Ujoints for the m47 are all on the back shaft.

 

[Alan29]

@shoestring Yeah it's the parts I bought from you (thanks again for crating it down to me).

In your experiences with these cars was it only the 93 that had this coating? Been reading about it possibly being a last year only thing...were these just lubed up with some kind of "lifetime grease" before? Seems like it would need service intervals to grease the splines without any coating.

Since it's already peeled off the one part I'm strongly considering experimenting with removing it to see what happens on the car. Worst case I get another back half I guess.

 

[shoestring]

@shoestring Yeah it's the parts I bought from you (thanks again for crating it down to me).

In your experiences with these cars was it only the 93 that had this coating? Been reading about it possibly being a last year only thing...were these just lubed up with some kind of lifetime grease before?

Since it's already peeled off the one part I'm strongly considering experimenting with removing it to see what happens on the car. Worst case I get another back half I guess.

I never really looked that closely because they always just kinda went together for us. I don't hate your decision at the end there. If it's too loose though, you don't want it chewing up the front half.

 

[Alan29]

I never really looked that closely because they always just kinda went together for us. I don't hate your decision at the end there. If it's too loose though, you don't want it chewing up the front half.

It's easy to overlook. I didn't even notice until I saw it chipping and shit myself thinking I somehow boogered a spline.

My other thought, which I might try first, is sanding it down a bit. It was just barely into the raised portion of the coating. The part that chipped up I believe is that overfilled section @lookforjoe mentioned.

I'm going to give it a real good clean and another inspection before I take any drastic measures. I'll keep the thread updated in case anyone else runs into this.

As usual I appreciate all the info.

 

[blkaplan]

Dont try to mix and match the halves. You should use a complete m47 DS assembly. I am pretty sure they are balanced as an assembly and even if it did fit together. Chances of vibrations are there.

 

[Alan29]

I never really looked that closely because they always just kinda went together for us. I don't hate your decision at the end there. If it's too loose though, you don't want it chewing up the front half.

With all the mix and match shafts you've worked with in the past were you always finding they balanced okay if the factory arrows were matched up?

 

[shoestring]

100%. Like I've said before, we've run them to nearly 7000 driveshaft rpm and never had a problem. From a production standpoint, it doesn't make sense to me that they would be balanced as assemblies. Engines aren't. Doesn't it make more sense that you would balance them as components and then put them together? Same with turbo hot and cold wheels, at least factory ones. We've just used real Mitsu parts and put them together, never worried about balance or orientation. Manufacturers are the origination of milspec: the best possible result for the least amount of money. They also have the burden of warranty repair if it's wrong.

I was thinking about this more last night, and I have to imagine that when the M47 was swapped into our 1993, my buddy used the whole driveshaft from the '88 as he'd bought the whole car. I think it might make sense, if that's the case, that maybe there's a change for 1993 that doesn't work. I believe the 940 that had this problem was also a '93? I also know that the GCP catalogs aren't 100% complete, there are holes here and there.

I'm speculating, but not about the driveshafts. Done it a dozen times.

 

[blkaplan]

Why are you trying to mix and match.

 

[lookforjoe]

Yeah probably right. My other option is having a shop modify my aw70 front for the m47... although I don't even want to know what they'd want to charge for it.

There are no ujoints to compare on the m47 half...it's a straight shaft with the three bolt flange to the trans with guibo. Ujoints for the m47 are all on the back shaft.

Yes - I have one in the garage, but from a 700