Driveshaft install- does it really fit?!

[benbobs]

Hi All,

After spending the mandatory hour trying every which way to get the driveshaft to mate with the transmission I still can’t get the thing in. After reading the few threads on this, that seems to be the main advice but try as I might I just can’t get mine in.

I desperately don’t want to remove the engine unless it’s the absolute last resort. Well, technically removing the diff is the last resort. But you know what I mean! What’s the procedure here?

What’s the best angle to offer up the drivetrain? Should I be trying to get the shaft in from above the diff adapter somehow (as implied in the manual)? (That seems very tight).
Or from below?

Is there a place to move the transmission so I don’t have to remove the whole thing from the car?
I already adjusted the transmission height for the pinion angle with spacers. Should I remove this and drop the transmission down as low as possible (ie sitting on the a frame / 3inch cross member)?
Or raise it?
How about shifting it to one side or the other with a pry bar?

Please help if you’ve done this and know the knack. Pulling the engine would be a very sad (and long) day if I have to do it, and it feels like there’s a trick here I’m missing.

My transmission is a TKX on a BP347, I have IRS and I removed that rubber bung thing from the end. The spindle on the driveshaft was also covered in transmission oil in a vain attempt to see if that might help. It didn’t.

Thanks all, and happy holidays

Ben

[CaptB]

You may have the wrong driveshaft. Also Moser has an app that will tell you if your pinion angle is correct for your install.

[runamuk]

Do you have a solid axle or IRS?

I have an IRS and I had to remove my trans mount and loosen the engine mounts, then I pried the transmission as far to the left as I could while I worked the driveshaft into position.

[benbobs]

Do you have a solid axle or IRS?

I have an IRS and I had to remove my trans mount and loosen the engine mounts, then I pried the transmission as far to the left as I could while I worked the driveshaft into position.

Thanks- So you’re saying there’s hope!!
Did you lower the trans down or raise it?

Did you offer up the driveshaft from below? I can’t see how I can bring it in from above the diff shaft.

Ben

Did you

[benbobs]

I have a digital level- the pinion angle was set to be equal on both sides with the spacers. I was planning on double checking once the diff was installed. I think it’s the right shaft. Right number of notches in the spindle and the length looks good. Just can’t get it into the transmission due to the angle.

[edwardb]

I always put them in from the bottom, and that's what you want anyway. Any future maintenance would be that way. If the spline counts between the transmission output shaft and the driveshaft slip yoke are the same, you should be able to bend the U-joint and get the slip joint started into the transmission. Since you have that shipping piece removed, it should go in. But it has to be aligned exactly. It's a very precise fit. If the angle you're trying to go in is different than the transmission, it likely won't start. Once it does, should slide all the down to the external seal on the transmission output. At that point the driveshaft should swing up and align with the flange on the diff. Driveshafts that are the proper length will allow it to swing in and when pulled tight against the flange, expose around 1/2" of the slip flange at the transmission.

If none of the above is part of your experience, something is wrong IMO. Loosening the engine, the rear axle, moving things around, pry bars, etc., shouldn't be part of the experience. Surprised how often I see this and always makes me go hmmm. Pinion angle is important, but whether it's right or wrong at this point shouldn't affect installing the driveshaft.

[benbobs]

I always put them in from the bottom, and that's what you want anyway. Any future maintenance would be that way. If the spline counts between the transmission output shaft and the driveshaft slip yoke are the same, you should be able to bend the U-joint and get the slip joint started into the transmission. Since you have that shipping piece removed, it should go in. But it has to be aligned exactly. It's a very precise fit. If the angle you're trying to go in is different than the transmission, it likely won't start. Once it does, should slide all the down to the external seal on the transmission output. At that point the driveshaft should swing up and align with the flange on the diff. Driveshafts that are the proper length will allow it to swing in and when pulled tight against the flange, expose around 1/2" of the slip flange at the transmission.

If none of the above is part of your experience, something is wrong IMO. Loosening the engine, the rear axle, moving things around, pry bars, etc., shouldn't be part of the experience. Surprised how often I see this and always makes me go hmmm. Pinion angle is important, but whether it's right or wrong at this point shouldn't affect installing the driveshaft.
Thanks for the note.

The issue seems to be the length of the splined shaft is so long that the driveshaft (even when all the universal joint are bent fully won’t clear the end of the diff). No matter how I angle it the shaft is too long. When I measure the length of the shaft ignoring the splined section the driveshaft appears to be the right length- it’s just a clearance issue.

Have you installed a similar set up to mine ? (IRS, TRX, 347). From reading similar threads it seems that folks primarily with IRS have had this issue. I’m scratching my head to work out what I could have done wrong but everything else lines up. And the center section has no give whatsoever, so the only variable is the transmission mount.

[rich grsc]

Good grief, the engine mounts are rubber. Take the bolts out of the transmission mount, use a pry bar to move the transmission, either up down or side to side till you can slide in the driveshaft. How difficult can that be????

[benbobs]

Good grief, the engine mounts are rubber. Take the bolts out of the transmission mount, use a pry bar to move the transmission, either up down or side to side till you can slide in the driveshaft. How difficult can that be????

Thanks Rich. Merry Christmas.

[benbobs]

Thanks for those that helped reassure me on this. For anyone else struggling with this, I managed to get this in.
I dropped the trans down all the way so it sat on the crossmember and used a pry bar to push it towards the driver side as far as it would go. With a few minutes finagling it slipped in. I let out a quiet whoop and went for a walk outside.

For many of us this is the first car we’ve built. I realize it must be exasperating for some here that we don’t know everything but for those of you who don’t mind “stupid” questions like this, and take the time help out, I wanted to say a huge thank you. It makes this forum what it is.

Ben

[CaptB]

For many of us this is the first car we’ve built. I realize it must be exasperating for some here that we don’t know everything but for those of you who don’t mind “stupid” questions like this, and take the time help out, I wanted to say a huge thank you. It makes this forum what it is.
n

Trust me this isn't the dumbest question someone has asked. Some folks could use some soft skills on their replies but I've asked several goofy ones here.

Capt. B

[JohnK]

Not a dumb question at all, and you're definitely not hte first person to struggle with this. Glad you got it sorted out. Some people here are incapable of giving out advise without making you eat a little s*&% along with it. Just ignore them.

[edwardb]

Thanks for those that helped reassure me on this. For anyone else struggling with this, I managed to get this in.
I dropped the trans down all the way so it sat on the crossmember and used a pry bar to push it towards the driver side as far as it would go. With a few minutes finagling it slipped in. I let out a quiet whoop and went for a walk outside.

For many of us this is the first car we’ve built. I realize it must be exasperating for some here that we don’t know everything but for those of you who don’t mind “stupid” questions like this, and take the time help out, I wanted to say a huge thank you. It makes this forum what it is.

Ben

Congrats! Now that you have it in, and the flange bolted to the diff, how much of the slip joint is exposed at the seal out the back of the transmission? That's an indicator that the driveshaft was the right length (or not). And to your question before, yes I've put in several of these including a similar combination as yours. But the one closest I had a custom one made. Went it without as much drama.

[Alec]

Is there a good way to avoid this? Can the driveshaft be preinstalled onto either the diff or the trans prior to dropping the motor/trans in? Coming up very soon in my build.

[Jryasko]

Ditto on what Paul says (edwardb), with the driveshaft installed you should have some of it out away from the seal on the transmission side. If it is right up to the trans something is wrong.

[Jim1855]

I suppose if you stopped the engine install at a point when you could slide the driveshaft into the trans and then continued into position things would be a bit easier. Might take two people, one on the hoist and one underneath to guide the driveshaft / trans into position.
It would be a great idea to test fit the driveshaft in the trans tailshaft prior to any installation.
If all of that fails, just lift the engine up above the mounts and pull it forward.
Jim

[Theshandman]

...How difficult can that be?
LOL! In hindsight, not too difficult. In foresight, Damn!!! :-)

[edwardb]

Is there a good way to avoid this? Can the driveshaft be preinstalled onto either the diff or the trans prior to dropping the motor/trans in? Coming up very soon in my build.

Not to beat a dead horse... but if it's the right length that's not necessary. But with everything apart, a very good time to make sure the rubber donut is out of the back of the trans (if it's one that has one) and also a good time to check the fit of the slip joint into the trans. I always do that on my builds before assembly to make sure the flange counts match. Make sure it slides all the way in up to where the U-joint lightly touches the seal. The final position will be out for there (it has to be) but confirms all is OK. Also, if you haven't done this before, gives you an idea of how they go together instead of trying for the first time with everything in the chassis.

[rich grsc]

Thanks Rich. Merry Christmas.
Sorry if that came across as too harsh. So many 'issues' can be resolved by just having a look at it, and give something a try.

[facultyofmusic]

I couldn't get the driveshaft to fit when the engine in place either. Luckily I already planned to pull the engine out again, so during the final install I quickly crawled under the car and slipped it into the tranny when the engine was still hovering. I understand that it's technically possible if you drop the tranny enough and then force it to the right, but that's a lot of work that could be avoided if you plan ahead, which it sounds like you indeed are. During your engine install you're gonna keep the engine covering a tiny bit forward to install the headers anyway. That's the perfect time to slip the shaft in.

If it helps I have a coyote+T56 magnum and IRS. It's a configuration that's known for having not much space back there.

[AA-ron]

Like most I too had problems getting my drive shaft installed. I'm running a t-5 with IRS setup.
I found some good advice on the forum that allowed me to get it installed. I loosened the motor mounts, trans mounts, and with the use of a pry bar, I flexed the transmission to the left side, and it moved JUST enough to let me slide the drive shaft into place. I was convinced i had the wrong driveshaft as I had probably an hour into trying and failing. It wasn't until I did the above that it slid in to place.

[Fman]

Is there a good way to avoid this? Can the driveshaft be preinstalled onto either the diff or the trans prior to dropping the motor/trans in? Coming up very soon in my build.

To answer your question yes when installing the engine attaching the driveshaft when trans slides into the tunnel is a great time to do it. We just did this on TedG's 427 build on his engine install last month and it worked perfectly. I also had a difficult time installing my drive shaft and I have a two post lift doing it standing up under the car.

[runamuk]

Thanks- So you’re saying there’s hope!!
Did you lower the trans down or raise it?

Did you offer up the driveshaft from below? I can’t see how I can bring it in from above the diff shaft.

Ben

Did you

I stood on the right side of the car so I could pry the transmission over to the left side with a 2x4, with the tailshaft of the transmission pointing to the left side I worked the driveshaft into place until the yoke slid into the back of the transmission. Dont forget that the transmission comes with a plug in the back to seal it up and it looks like part of the seal, this plug needs to be removed.