[reductive]

Hello all, first post. I'm rebuilding an N54, and in the case that i wanted to get pretty serious with the build, since I have the motor apart, I might want to lock the crank hub.

The only option I'd consider purchasing (due to cost) )is Vargas' (VTT) splined hub. The pinned hub from maximum psi looks good but is too expensive, not to mention the relatively small cost of drilling the crank, but its still even more $...

...Anyway here's my question. Why don't we just weld/grind/balance the whole assembly? Worst case scenario if you wanted to change your oil pump and/or timing sprockets, the welds would be one the outside, and could be carefully ground out and redone, and rebalanced

Welding and balancing is cheaper than the cheapest fabricated option I think. It'll be a while if I ever get to it but I'm interested if anyone has done this or is more confident in their knowledge of the materials and processes so could tell me if this would or why this wouldn't work.


Thank you

[N54_ABQ]

Its a good idea and could save some money up front but assembly would be tricky.
My crank hub slipped once from a money shift. Luckily no damage occurred and it just needed to be retimed. But I've been looking for a cost effective solution as well.

The problem with welding the sprockets and hub lies with assembly. The chains would have to go in at the time the crank and bed plate go on. The chains would be completely captive at that point. If chain replacement is required the crank has to come out...

As far as welding and material science there might be reasons that would make it undesirable as well.

Not impossible but can make things complicated in the future an may not end up being cheaper than the Spline Lock.

[reductive]

Originally Posted by N54_ABQ

Its a good idea and could save some money up front but assembly would be tricky.
My crank hub slipped once from a money shift. Luckily no damage occurred and it just needed to be retimed. But I've been looking for a cost effective solution as well.

The problem with welding the sprockets and hub lies with assembly. The chains would have to go in at the time the crank and bed plate go on. The chains would be completely captive at that point. If chain replacement is required the crank has to come out...

As far as welding and material science there might be reasons that would make it undesirable as well.

Not impossible but can make things complicated in the future an may not end up being cheaper than the Spline Lock.

This is a good point that hadn't crossed my mind as my bottom end was already apart. Do chains stretch much in higher horsepower engines? I wouldn't know. But even for having to remove the bedplate and crank to service the chain it's still considerably cheaper. If you can weld yourself, and if your engine is out, and if the crank is getting balanced, which is where I'm at with this, it seems like welding is the way to go.

i'm not even familiar with the car but if you had to drop subframe and stuff to get the crank out then the few hundred dollar difference becomes more worthwhile esp considering servicing the chain.

[320IN54]

I was just over at the M2 Forums and looked over at the S55 thread. Apparently this is the reason why BMW has never created a fix for the crank hub failures

BMW comment:
BMW saw this issue first time on an engine test bed long time before the first vehicle was delivered. The same issue is known from a 4 cyl engine - same parts/system. The real problem is not the hub (2) or the wheels (5). It´s the bolt (3), which holds the wheel and crank hub. The bolt dissolves because of vibrations coming from the vibration damper (1) in front of it - or from any other imbalanced source. If it dissolves, your chain wheel spins and timings adjusts. So why not just tighten the bolt, or make the hub and wheels from one piece? Because this system works like a fuse. This "fuse" protects your crankshaft against imbalanced parts and vibrations. If you fix the bolt (weld etc), it can't come loose and you risk damages to your crankshaft and bearings etc. The "solutions" some tuners offer are very dangerous, BMW constructed everything for a reason. Example? You can't (or its very difficult) set timings with a fixed wheel. We spoke honestly with the engineer, about solutions, whats possible. The reality is: there's no solution. You can fix the bolt but you open a range of new risks. You can install a one piece hub/wheel - and of this the engineer urgently advised against - you risk even more damages. JoeFromPA is right - there are over 40k vehicles and just round about 40 (BMW said this) known cases, most of them with only wrong timings. You even can't check the bolt, only thing you can do is change the bolt every year or every xxxxx miles/km. The bolt is tightened with 200 Nm and 2x 260 degrees

There have been people who tried to fix the problem with the aftermarket solutions created and they have not experienced anything catastrophic but nobody knows as the kits have not been tested for an extended amount of time. Then again the N54 engine has been around much longer than the S55.

[reductive]

Originally Posted by 320IN54

I was just over at the M2 Forums and looked over at the S55 thread. Apparently this is the reason why BMW has never created a fix for the crank hub failures

BMW comment:
BMW saw this issue first time on an engine test bed long time before the first vehicle was delivered. The same issue is known from a 4 cyl engine - same parts/system. The real problem is not the hub (2) or the wheels (5). It´s the bolt (3), which holds the wheel and crank hub. The bolt dissolves because of vibrations coming from the vibration damper (1) in front of it - or from any other imbalanced source. If it dissolves, your chain wheel spins and timings adjusts. So why not just tighten the bolt, or make the hub and wheels from one piece? Because this system works like a fuse. This "fuse" protects your crankshaft against imbalanced parts and vibrations. If you fix the bolt (weld etc), it can't come loose and you risk damages to your crankshaft and bearings etc. The "solutions" some tuners offer are very dangerous, BMW constructed everything for a reason. Example? You can't (or its very difficult) set timings with a fixed wheel. We spoke honestly with the engineer, about solutions, whats possible. The reality is: there's no solution. You can fix the bolt but you open a range of new risks. You can install a one piece hub/wheel - and of this the engineer urgently advised against - you risk even more damages. JoeFromPA is right - there are over 40k vehicles and just round about 40 (BMW said this) known cases, most of them with only wrong timings. You even can't check the bolt, only thing you can do is change the bolt every year or every xxxxx miles/km. The bolt is tightened with 200 Nm and 2x 260 degrees

There have been people who tried to fix the problem with the aftermarket solutions created and they have not experienced anything catastrophic but nobody knows as the kits have not been tested for an extended amount of time. Then again the N54 engine has been around much longer than the S55.

thank you for the critical information. the bolt "dissolves" lol. this is to prevent wear on the crankshaft and block? so we should just replace the bolt and the friction washers at an interval... i wonder if scoring the mating surfaces of the parts would increase lock or decrease

[Herman E. Valdez]

yes you are right. it will create problems for you sometime. but there are some points you are missing here. most importantly, you are not applying the weldingin proper sense. I think it is the only cheapest and best ever way you can apply for this purpose.

[mikecooper]

Originally Posted by Herman E. Valdez

yes you are right. it will create problems for you sometime. but there are some points you are missing here. most importantly, you are not applying the weldingin proper sense. I think it is the only cheapest and best ever way you can apply for this purpose.

Of course your right, this problem can be overcome with the help of proper welding and this is the best and cheapest way to minimize the friction of bolt in BMW

[amsnow440]

Has anyone just tried using a retaining compound a la Loctite 638?

[Saif2018]

Originally Posted by 320IN54

I was just over at the M2 Forums and looked over at the S55 thread. Apparently this is the reason why BMW has never created a fix for the crank hub failures

BMW comment:
BMW saw this issue first time on an engine test bed long time before the first vehicle was delivered. The same issue is known from a 4 cyl engine - same parts/system. The real problem is not the hub (2) or the wheels (5). It´s the bolt (3), which holds the wheel and crank hub. The bolt dissolves because of vibrations coming from the vibration damper (1) in front of it - or from any other imbalanced source. If it dissolves, your chain wheel spins and timings adjusts. So why not just tighten the bolt, or make the hub and wheels from one piece? Because this system works like a fuse. This "fuse" protects your crankshaft against imbalanced parts and vibrations. If you fix the bolt (weld etc), it can't come loose and you risk damages to your crankshaft and bearings etc. The "solutions" some tuners offer are very dangerous, BMW constructed everything for a reason. Example? You can't (or its very difficult) set timings with a fixed wheel. We spoke honestly with the engineer, about solutions, whats possible. The reality is: there's no solution. You can fix the bolt but you open a range of new risks. You can install a one piece hub/wheel - and of this the engineer urgently advised against - you risk even more damages. JoeFromPA is right - there are over 40k vehicles and just round about 40 (BMW said this) known cases, most of them with only wrong timings. You even can't check the bolt, only thing you can do is change the bolt every year or every xxxxx miles/km. The bolt is tightened with 200 Nm and 2x 260 degrees

There have been people who tried to fix the problem with the aftermarket solutions created and they have not experienced anything catastrophic but nobody knows as the kits have not been tested for an extended amount of time. Then again the N54 engine has been around much longer than the S55.

Crank hub failure anywhere near as "common" as the S55?

Also any info on how BMW fixed this issue for the S58?