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I have read many posts regarding the difficulties some have installing the driveshaft and unfortunately find myself in that camp. I have a BPE347 mated up to a TKX transmission with IRS and I needed to shim the tail of the transmission up 0.75" during install to get the angles and alignment right. My driveshaft and transmission each have 31 splines, so that checks out fine. I have spent the obligatory 1 hour trying, but I cannot for the life of me get the shaft inserted into the tail of the transmission. Before I unbolt the engine and transmission to wiggle things around a bit I wanted to confirm I had the correct driveshaft, as I think if it were 0.75-1.00" shorter I could get it inserted.
The shaft that needs to fit into the transmission is 4.5" long and the entire driveshaft is 12 7/8" long. Does this sound correct? I read on a post that FFR lengthened the shafts on the driveshaft some time ago, but a shorter shaft would be better for me at present.
Thank you
JJK
red.barchetta
04-30-2023, 06:37 PM
Here’s a mistake I made that might help you. I made the mistake of not removing the “shipping” plug in the end of the TKX. I used a pair of needle nose and worked it out. I got my driveshaft to slide in no problem after.
I even forgot the plug after reading about it in Fman’s build thread…… whoops
rich grsc
04-30-2023, 07:24 PM
Why did you shim the tranny if you don't have the driveshaft installed, and how did you measure the angles?
red., yeah I removed the plug, so that is not an issue.
Rich, I horizontally aligned the IRS mounting plate to the transmission output shaft to within 1/8" and this put the angle of the transmission within 2 degrees of the pumpkin input. I recognize I may need additional shims once the driveshaft is in to finalize the pinion angle but I wanted to get things as close as possible ahead of time. Perhaps removing the shims will get the angles such that I can get the shaft inserted into the transmission, then I can reshim as needed.
CraigS
05-01-2023, 06:39 AM
Try taking the bolts out of the trans mount and see if that gives you enough movement to get the shaft in. It may take some muscle to move the trans because you have to flex the engine mounts for it to move. You might also need to drop the trans a-frame.
edwardb
05-01-2023, 10:19 AM
This is probably very obvious, but if you haven't done this before, the driveshaft pinion flange needs to be lined up exactly straight to the transmission input in order to go in. Until it is, it won't go in. When straight, it will probably surprise you how easy. Typically you can position the driveshaft with the U-joints fully angled to get the pinion flange lined up. Once in, you will align to the transmission flange. Typically some of the slip joint is exposed. But not too much. If the driveshaft is too short, the exposure will be too much.
EK1965
05-01-2023, 01:26 PM
I also had the wrong drive shaft for the same configuration, it should be 8.375"
EK1965, can you elaborate on your 8.375" dimension. Is that the total length, whereas mine is currently 12.875"? Or is that 8.375" dimension only part of the driveshaft?
edwardb
05-01-2023, 02:45 PM
Factory Five's order configurator lists part number 16038 for your combination at 8.375". This one https://www.factoryfiveparts.com/16038-roadster-31-spline-8-375-driveshaft/. Is that what's on your order and inventory listing? The dimension is the distance from the center of the front u-joint to the rear flange. It does not include the slip yoke.
edwardb, thank you for confirming. It looks like I have the correct driveshaft, so I will now proceed to unbolt the engine and trany to see if I can wiggle enough room to get the driveshaft inserted.
rich grsc
05-01-2023, 05:11 PM
No need to unbolt the engine, just the transmission mount. The rubber mounts will easily flex.
EK1965
05-02-2023, 09:41 AM
Looks like you have the answer. I had to disconnect the trans tail to get it in, but I am an amateur. Its insane, the shaft is just a few inches long, yokes and spline make up the majority of the length.
Just to close this out, I was able to get the driveshaft installed by removing the transmission mount spacers I initially used, loosening the engine mounts, and then pulling the transmission down and to the drivers side while someone else inserted the driveshaft. Once installed, 0.8" of spacers raised the transmission tail to near perfect pinion angle.
I couldn't figure out why my Metco safety loop was interfering with the driveshaft, then realized since I shimmed up the transmission by 0.8", I would also need to shim up the safety loop. All good now.
Thank you all for your help.
elspanishgeek
05-15-2023, 06:31 PM
Factory Five's order configurator lists part number 16038 for your combination at 8.375". This one https://www.factoryfiveparts.com/16038-roadster-31-spline-8-375-driveshaft/. Is that what's on your order and inventory listing? The dimension is the distance from the center of the front u-joint to the rear flange. It does not include the slip yoke.
I'm not sure if I'm understanding the measurement. I'm attaching pictures of mine, does this look correct? This is the only way I can measure 8.375'' but doesn't seem to match your description.
I have the exact same configuration, BPE 347 with TKX and 2015 IRS. I'm reading up on every thread possible on dropping the engine since I was aiming to do it this week and came across this post. Looks like a lot of issues with getting the driveshaft in after installing the engine and transmission?
184541
The lens is creating an angle and distorting the measurements in the previous picture, so I'm attaching these aligned close-ups of each end as well. To confirm, the ruler wasn't moved between any of these 3 photos.
184540
184542
JJK does this look like your 31 spline 8.375" driveshaft?
Yes, that appears correct. You can count the splines, there should be 30 with a space where a 31st would go. This is normal for a 31 spline. If I were to do it again, I would install the driveshaft before dropping the engine. Just secure it to the transmission so it doesn't fall out. Good luck.
JJK
elspanishgeek
05-15-2023, 07:21 PM
Yes, that appears correct. You can count the splines, there should be 30 with a space where a 31st would go. This is normal for a 31 spline. If I were to do it again, I would install the driveshaft before dropping the engine. Just secure it to the transmission so it doesn't fall out. Good luck.
JJK
Thank you for the quick response! To confirm (because now I'm paranoid), this is the correct way of measuring the 8.375'' length (from one end to the beginning of the rod of the spline yoke)?
correct, the yoke is not included in the 8.375" measurement.