Balancer Woodruff Key Repair?

[Ben C34]

4 hours ago, GTSBoy said:

Future Ben is a dickhead, so he gets what he deserves anyway.

I like to think future Ben isn't a dickhead but track record is not promising 😎

[TurboTapin]

It's not great, but it's far from terrible. I'd fill it back up with a tig in small increments and file it back down. Shitty spot to do it but doable in place with everything around it out of the way. 

Edited December 23, 2020 by TurboTapin

[GTSBoy]

Careful use of a dremel with a real small cutter in it required to machine down in the slot after welding. Not going to be fun. Steady hand required. I'd try to do it with the slot facing down, lying on my back with the crank snout at a comfortable height. Couldn't imagine being able to find a nice spot to do it from in front, unless radiator, cooler, AC condenser, front bumper all removed. And even then.

Conversely, I wouldn't want to weld it from underneath. Although that might work with delicate TIG action.

[CLEM0]

9 minutes ago, GTSBoy said:

Careful use of a dremel with a real small cutter in it required to machine down in the slot after welding. Not going to be fun. Steady hand required. I'd try to do it with the slot facing down, lying on my back with the crank snout at a comfortable height. Couldn't imagine being able to find a nice spot to do it from in front, unless radiator, cooler, AC condenser, front bumper all removed. And even then.

Conversely, I wouldn't want to weld it from underneath. Although that might work with delicate TIG action.

I've got it all off besides bumper but there is room- but I only have a MIG welder right now, my TIG died.
 

Hopefully MIG works (it should), I have a die grinder with a bunch of bits to sort the shaping. It's going to suck doing this but realistically a good fill of MIG on the broken side, filing it well, fitting the key firmly and loctite hopefully works. 
New balancer and bolt too.
 

Gotta figure out locking the flywheel!

People do loctite only on MX5s all the time- on the crank pulley itself!
If the bolt is tight- it SHOULD be fine.

Hoping it goes well cheers for advice.

[GTSBoy]

9 minutes ago, CLEM0 said:

Gotta figure out locking the flywheel!

It's not hard. If you have a little scrap flat plate and your MIG, you can make a locker that goes where the starter is, as per BK et al above. Just needs to have a couple of bolt holes and a piece welded on that will jam the teeth of the flywheel. Might take 2 shots to get it right, but you'll see what's needed as soon as you look through the spot where the starter was. Of course.....access there kinda sucks too. But that's what they make inspection cameras for.

[NZ-GTT]

Before you go tightening that bolt too much, have a read here: 

 I stretched that 1st bolt almost 1mm when compared to another 2 factory bolts. I then purchased an ARP bolt from Spool Imports but it did not come with torque specs, so used the recommended for a M16 bolt on the ARP website. Car is running now no issues yet. I just checked it last week.

With regards to the MIG welding, I'm no expert welder but a MIG does not penetrate very well. It would be better if you can get your hands on a TIG.

[CLEM0]

37 minutes ago, NZ-GTT said:

Before you go tightening that bolt too much, have a read here: 

 I stretched that 1st bolt almost 1mm when compared to another 2 factory bolts. I then purchased an ARP bolt from Spool Imports but it did not come with torque specs, so used the recommended for a M16 bolt on the ARP website. Car is running now no issues yet. I just checked it last week.

With regards to the MIG welding, I'm no expert welder but a MIG does not penetrate very well. It would be better if you can get your hands on a TIG.

Yikes. That doesn't sound fun. I've decided- Going to torque the factory one to factory specs first. I don't want to be going above and beyond if factory is fine to hold it all. #1 is making sure the bloody key fits!

[BK]

Your call, but 150Nm is fk all on a decent grade 16mm bolt. The lowest grade of 8.8 in these type of bolt for automotive in 16mm x 1.5mm is between 260 - 310Nm. If it's a 10.9 or 12.9 it's even higher. See why I say the factory manual is really strangely low ? RB25 manual in no way correlates to real world fastener specs.

Interestingly enough when you look up general bolt specs an 18mm x 1.5mm , which is what an RB26 is, is recommended to be 425 - 460Nm for an 8.8 grade fastener. Factory RB26 manual states 440 - 466Nm. Coincidence ?

You don't want this happening again after you fix it.

[CLEM0]

2 minutes ago, BK said:

Your call, but 150Nm is fk all on a decent grade 16mm bolt. The lowest grade of 8.8 in these type of bolt for automotive in 16mm x 1.5mm is between 260 - 310Nm. If it's a 10.9 or 12.9 it's even higher. See why I say the factory manual is really strangely low ? RB25 manual in no way correlates to real world fastener specs.

Interestingly enough when you look up general bolt specs an 18mm x 1.5mm , which is what an RB26 is, is recommended to be 425 - 460Nm for an 8.8 grade fastener. Factory RB26 manual states 440 - 466Nm. Coincidence ?

You don't want this happening again after you fix it.

I was googling this as you replied. The manual is stupidly low, I wonder if it's a translation/conversion error, as it is really low.

Will crank it up a bit on the stock bolt, once I know the torque specs.

[NZ-GTT]

I would buy the ARP bolt and torque it to ARP specs.

[GTSBoy]

I would just like to point something out.

From an engineering perspective, it is absolutely unnecessary to torque a bolt up to anywhere near its recommended limiting torque. The correct torque will be whatever is required to produce the mechanical clamping force required in the joint. If that is only 150 Nm, then it's only 150 Nm. Normally an engineer would not then select a bolt that is massively more capable than that, because of cost. But in something like a crank pulley I'd be perfectly willing to believe that an engineer would perhaps happily go up a size or two, in order to obtain better numbers elsewhere, such as thread pitch, or area under the bolt head, or toughness/resistance to vibration or cyclical load. Any of a whole bunch or reasons.

Now, I'm not saying that 150 Nm is correct in this instance. But it is definitely true that it is enough to hold the pulley on. It may not be enough enough, especially when coupled with other things that can happen when 3rd parties (rather than the guy on the assembly line with the ISO 9001 system certified torque wrench) are refitting the pulley. There's about 15 different things that can be wrong or go wrong when somebody does this. But it might have been just fine for what is ultimately just a 250HP 2.5L six in a mass produced car.

The fact that the same manufacturer specs a much bigger number for other similar engines is a bit suspicious. But then the bolt is bigger and the intended usage model for the RB26 was also known to the factory to be "tuned and thrashed". So there might be a perfectly consistent logic in there.

Nevertheless, there is no way that I would be arbitrarily torquing the stock RB25 crank pulley bolt up to 400Nm. Seems like waaaaay too big a step up from 150, and waaaaay high compared to 8.8 rating. It's not likely to be any better than 8.8, and might not even be that good, because it is quite possibly oversized for the duty. But, I wouldn't have too much problem with picking a number like 250Nm and doing it up to that. It's unlikely to go anywhere at that torque, and it's unlikely to stretch the bolt or wreck a thread, etc.

[BK]

 

28 minutes ago, GTSBoy said:

Nevertheless, there is no way that I would be arbitrarily torquing the stock RB25 crank pulley bolt up to 400Nm.

Definitely on the high side for a 16mm bolt. The facts remain though - keyway is stuffed on crank and really only one way that can happen.

15 hours ago, NZ-GTT said:

I would buy the ARP bolt and torque it to ARP specs.

 

16 hours ago, NZ-GTT said:

I then purchased an ARP bolt from Spool Imports but it did not come with torque specs, so used the recommended for a M16 bolt on the ARP

Didn't come with torque specs because it's not designed for an RB25. ARP do not list a crank bolt for RB20, 25 or 30 and nowhere else sells one for them either, except Spool imports.

I call bullshit on this.

Their "supposed" ARP crank bolt for a 25 is twice as expensive as an ARP RB26 one from anywhere else.

Obviously something from another model and is similar. Similar doesn't mean correct though.

[NZ-GTT]

12 minutes ago, BK said:

I call bullshit on this.

Their "supposed" ARP crank bolt for a 25 is twice as expensive as an ARP RB26 one from anywhere else.

Obviously something from another model and is similar. Similar doesn't mean correct though.

Most likely is the case since the RB26 ARP bolt comes with the washer and the "supposed RB30 bolt does not. You have to reuse the factory washer.

[BK]

You didn't happen to measure the overall bolt and thread lengths between a factory bolt and the ARP bolt for comparision ?

[NZ-GTT]

Not accurately but side by side they looked to be identical as in number of threads and length of the shank.

[cyman]

hello, sorry to revive an old thread. Did you actually fix the issue ? I and my friend are having a similar problem, trying to find a solution to the loose vibration dampener. 

 

it actually destroyed the key. do you thing is fixable?

its an rb30 crankshaft into an rb26 block

 

 

[CLEM0]

On 6/8/2022 at 10:20 PM, cyman said:

hello, sorry to revive an old thread. Did you actually fix the issue ? I and my friend are having a similar problem, trying to find a solution to the loose vibration dampener. 

 

it actually destroyed the key. do you thing is fixable?

its an rb30 crankshaft into an rb26 block

 

 

Hey mate. No trouble - still active thread. Happy to help.

Unfortunately unless you have a great machine shop (I found one who would weld the entire nose of the crankshaft- re-cut the keyways, and grind it exactly back to spec) but it cost more than a used crank as it's a lot of work.

As for what I did: New-ish condition second hand crank, polished it, new ACL bearings, extended crank collar, made my own custom keyway, and had machine shop cut the slot for it (NOT REQUIRED- THIS IS NOT THE ACTUAL ISSUE, OEM keyways are totally fine, they should never hold pressure like Nissans seem to- I realised this later) and put it all back together with a brand new OEM bolt.

However- the brand new OEM balancer- on a great condition crank, measured perfectly in spec with a micrometer, still slips on by hand. Both balancer and crank were factory spec, measured by micrometer..... They're not made right- ever. The only fix is a high end balancer, such as Ross, as well as a new timing gear- I went with PRP but didn't use their trigger kit- just the timing crank gear. Both fit extremely snug- still able to get on with a balancer assembly tool (the fact a tool exists for this task and Nissans balancers don't require it is worrying enough) and it fits tight interference. Snug as it should be- normal ~150nm torque on bolt. Good to go.

Do not use a factory OEM balancer if you can- get a new/used crank, OEM/Nitto keyways + high end balancer and (non nitto- they're loose) timing gear. PRP fit snug. Nitto do not. Nor does OEM Nissan. Get it all back together. Not worth saving that crank IMO- but it's possible.

However: No point saving the crank then repeating the exact same issue. If you do get it machined- have it done the tiniest bit oversized to compensate for the shitty balancer tolerances- that'd probably work too. Heat on the crank snout is bad however, so would I use a welded crank for a high power/rpm build? Not a single chance whatsoever. Especially given the harmonics that are capable of cracking oil pumps- i'm sure they could hurt a snout of a crank too, if it's been welded and heated in one spot.

It's quite funny to me even high end builders- such as Lewis Engines, don't notice this. They just say torque the bolt to obscene levels- like 450+nm of torque, as it masks the issue- not fixes it. Obviously no high RPM or high power cars use factory balancers so they seem to survive, but give it 5 years and it'll be back to square one again, as harmonics gradually loosen the bolt as the balancer clearances allow it to shake still, as the tolerances are wrong.

 

Good luck mate. It's not a hard fix- buy the high end balancer- it is the only proper, safe fix in all circumstances.

Apologies for the long reply- I want anyone else suffering this issue to realise exactly why it's happening, and how to fix it with no corners cut.

[BK]

The timing gear shield washers are actually more of the culprit on all RBs - they compress and the whole assembly eventually comes loose no matter how much you tighten.

Ross have the best solution for this with the shields either side of the gear machined with a large step into them to increase the thickness of the loaded area which fits into the gear itself. They are also made out of a lot harder steel.

[cyman]

 

thank you for the prompt and comprehensive answers and solutions to my problem. the real problem is that this is a custom crankshaft(builder no longer offer it) made from a famous builder, in australia and then shipped to my country. so its a an rb26 stroker (2.9L) using an rb30 crankshaft. so first we have to remake the used crankshaft(i think the crankshaft is destroked and and with smaller counterweights). Machine shop will have to measure and  replicate the crankshaft.

in deed this rb storker was pushing like 900whp on an ati vibration dampener but we were unaware(naive) that the age of the dampener does matter(it was 10 years old when we first bought it, and used it as it seems to be good at the time of the build) also we used oem bolt and torque specs of that of an rb30. Buy the time we increased the power, soon enough we had this issue.

so to summarise it up, we need:

• an aftermarket balancer that will have very tight fit like Ross,
• after market timing gear like the Ross or RPR
• Nitto keyways

Do you think that using ARP crankbolt is good to be used just to be on the safe side? 

thank you.

[Duncan]

Definitely go the ARP bolt on a big power RB30. The RB26 bolt is much larger/tighter.