*Upgraded DRIVESHAFT install/solution *

[dentprotony@gmail.com]

Hey fellas, so i finally made some time to install my upgraded driveshaft that was custom made for me a few weeks ago. New unit has longer splines section that goes furter into the transfer case and prevents DS from wearing the splines and creating excessive stress on the ujoints.

When the driveshaft/ujoints break, it either takes out the front diff (cracks the housing) and damages the oil pan (chancing oil starvation to the engine) , or it damages the transfer case and beats up the transmission housing. Either way causing thousands worth of damage and the bad part is that the new driveshaft doesn’t solve the short splines issue.

Overall job wasnt bad at all, id say 1-1.5hrs start to finish), i had to remove engine bottom splash shield , also removed the metal heat shield that is located right below the driveshaft, and moved the hose that this heat shield is sitting on top of. Then loosen 4 Etorx bolts, slid the driveshaft forward to the side/under the front diff, it slid out of the tcase and that was pretty much it. I used light coat of antiseize on the new splines, i also would strongly suggest cleaning the splines inside the tcase to make the installation easier.

As you see in one of the pictures, factory driveshaft only goes in about 20mm inside the transfer case, leaving 20-25mm of the splines surface unused (see pic). Over time , temp and vibrations create wear in the splines causing factory driveshaft to work its way out of the tcase creating major stress on the ujoints and eventually breaking/blowing up. New driveshaft has longer splines eliminating any possible chance for vibrations/splines wear resulting in much longer life and avoiding all the damage that stock DS can cause.

I am also considering making a safety loop for the front ds for our platform, this coming week ill talk to the local driveline shop to see if they can replicate my upgraded driveshaft using high quality ujoints and making them serviceable if needed. Will also talk to my machine shop to see what we can come up in terms of the driveshaft loop to avoid costly damages broken ujoints/driveshaft can cause.

Please let me know if you think there would be any demand in the driveshaft/safety loop or both. I believe this should eliminate the fairly common risk of the DS failure and bring years and years of trouble-free service

[EuroCarFan]

Great stuff Tony.

To clarify, in your second paragraph, you noted that the new driveshaft doesn't solve the short splines issue but in the fourth paragraph, you explained how it does prevent damages and stuff. Seems contradictory unless I'm reading it wrong?

Assuming the new driveshaft is a potential fix for these issues, are you selling them and what is the cost? Does this also fix the transfer case issue that causes the car to jerk at certain speeds? Would a combination of using these and a tc fluid flush/recalibration, solve that problem?

[dentprotony@gmail.com]

Originally Posted by EuroCarFan

Great stuff Tony.

To clarify, in your second paragraph, you noted that the new driveshaft doesn't solve the short splines issue but in the fourth paragraph, you explained how it does prevent damages and stuff. Seems contradictory unless I'm reading it wrong?

Assuming the new driveshaft is a potential fix for these issues, are you selling them and what is the cost? Does this also fix the transfer case issue that causes the car to jerk at certain speeds? Would a combination of using these and a tc fluid flush/recalibration, solve that problem?

Hey man, i meant bmw replacing these driveshafts on a recall doesn’t fix the short spline issue. The shaft that I installed today does. I have an appointment at the driveline shop this Tuesday to see if they can replicate this driveshaft using my old shaft as a core and copy/make the splined section. Hopefully will be able to get them done locally using gmb or INA ujoints. I also have a design for a driveshaft loop mocked up, will see if i can get that done as well

[EuroCarFan]

Originally Posted by dentprotony@gmail.com

Hey man, i meant bmw replacing these driveshafts on a recall doesn’t fix the short spline issue. The shaft that I installed today does. I have an appointment at the driveline shop this Tuesday to see if they can replicate this driveshaft using my old shaft as a core and copy/make the splined section. Hopefully will be able to get them done locally using gmb or INA ujoints. I also have a design for a driveshaft loop mocked up, will see if i can get that done as well

Thanks for the clarification.

Let us know if/when you will be able to market these and how much you estimate them to cost. Personally, I would rather buy a new unit instead of sending my current one in to get modified. Wouldn't mind sending it after the fact for a core exchange/refund though.

[dentprotony@gmail.com]

Originally Posted by EuroCarFan

Thanks for the clarification.

Let us know if/when you will be able to market these and how much you estimate them to cost. Personally, I would rather buy a new unit instead of sending my current one in to get modified. Wouldn't mind sending it after the fact for a core exchange/refund though.

Yes sir, it will be core exchange program , ill keep everyone posted !

[Blue By You]

Originally Posted by dentprotony@gmail.com

Hey man, i meant bmw replacing these driveshafts on a recall doesn’t fix the short spline issue. The shaft that I installed today does. I have an appointment at the driveline shop this Tuesday to see if they can replicate this driveshaft using my old shaft as a core and copy/make the splined section. Hopefully will be able to get them done locally using gmb or INA ujoints. I also have a design for a driveshaft loop mocked up, will see if i can get that done as well

Please keep us posted on the performance of the new driveshaft. Is the new one heavier/does it weigh more?

[dentprotony@gmail.com]

Originally Posted by Blue By You

Please keep us posted on the performance of the new driveshaft. Is the new one heavier/does it weigh more?

Good question, ill weigh them tomorrow, 100% slipped my mind 🤦*♂️, id say they are very close in weight

[9vapors]

Sorry I'm a noob, isn't that driveshaft portion with the splines the only parts that's changed? Why would we need a whole new driveshaft Vs just replacing that section?

[dentprotony@gmail.com]

Originally Posted by 9vapors

Sorry I'm a noob, isn't that driveshaft portion with the splines the only parts that's changed? Why would we need a whole new driveshaft Vs just replacing that section?

The parts that were changed are both ujoints (factory are non-serviceable staked units) and the extended splined section. But the goal is to keep the most of the stock driveshaft, replace both ujoints and add splined section. Hopefully will be able to get this lined up with the local drivetrain shop

[Chilled]

Hey, not nit picking.

Will your shop be giving a balance cert of the drive shafts. May help selling.

[dentprotony@gmail.com]

Originally Posted by Chilled

Hey, not nit picking.

Will your shop be giving a balance cert of the drive shafts. May help selling.

Driveshafts will be balanced, you can see weight in the picture 👍

[Blue By You]

Originally Posted by dentprotony@gmail.com

Good question, ill weigh them tomorrow, 100% slipped my mind 🤦*♂️, id say they are very close in weight

No sweat.

I'm pretty non-technical and just curious if any significant increase in weight would affect the speed at which the driveshaft could be turned? (almost like the difference in weight of wheels) I imagine any small weight increase would not be enough to make a difference, just curious.

Let us know how it feels when you drive it. And thank you for doing this on everyone's behalf!

[E36graduatebmw]

How frequent is this problem now the f85 has been out 7 years ???

[dentprotony@gmail.com]

Originally Posted by Blue By You

No sweat.

I'm pretty non-technical and just curious if any significant increase in weight would affect the speed at which the driveshaft could be turned? (almost like the difference in weight of wheels) I imagine any small weight increase would not be enough to make a difference, just curious.

Let us know how it feels when you drive it. And thank you for doing this on everyone's behalf!

Heres the weight comparison on the driveshafts

[dentprotony@gmail.com]

Originally Posted by E36graduatebmw

How frequent is this problem now the f85 has been out 7 years ???

Its been on and off, unfortunately could happen to some very low mileage examples and some higher mileage are still holding up, kinda unpredictable from what i can tell

[dentprotony@gmail.com]

Originally Posted by Blue By You

No sweat.

I'm pretty non-technical and just curious if any significant increase in weight would affect the speed at which the driveshaft could be turned? (almost like the difference in weight of wheels) I imagine any small weight increase would not be enough to make a difference, just curious.

Let us know how it feels when you drive it. And thank you for doing this on everyone's behalf!

The weight difference is negligent, DS diameter is very small , this tiny weight increase (if any) wont affect anything in terms of acceleration over stock DS

[Chilled]

Originally Posted by E36graduatebmw

How frequent is this problem now the f85 has been out 7 years ???

Frequent enough. Considering when they go, they can/do take out the engine, gearbox and even tear up the entire frame.

2x recent ish threads i've seen
https://f15.bimmerpost.com/forums/sh....php?t=1935420
https://f15.bimmerpost.com/forums/sh....php?t=1937323

More often than not, there is no warning or way to preemptively see if these things are about to let go.




Interestingly RealOEM has a new P/N from 2018 - 26209425907

[slow_roll]

Count me in for a Tony spec drive shaft

[Blue By You]

Originally Posted by dentprotony@gmail.com

The weight difference is negligent, DS diameter is very small , this tiny weight increase (if any) wont affect anything in terms of acceleration over stock DS

Nice!

[FirstBMWLA]

Interested

[dentprotony@gmail.com]

Ok quick update, had a meeting with the driveline shop, they suggested building new driveshaft vs upgrading stock one, they said fixing ujoints in place would be an issue as well as the factory driveshaft is put together using ‘friction welds’ and they would suggest normal bead welds. They asked for 2-3 days to measure everything and see if they can locate splines and flange and we will go from there 👍

[zeroping]

Interested also. Cheap insurance.