Balancer Woodruff Key Repair?

[CLEM0]

Hello,

I'm in the process of degreeing my cams, and upon removing the balancer for timing checks I noticed the woodruff key fell out straight away- and the slot looks minced! This is the keyway for balancer, not crank pulley.

 

How can I fix this? Does the key actually do anything besides align the timing marks for the balancer?

I have a MIG welder, loctite 660 and JB Weld readily available, as well as air tools to grind away etc...Can I just not run one and overtorque the crank bolt? Or should it be fixed?

I want to ideally fix in the car, because if it comes out for machining i'll rebuild the whole engine and just buy a new crank- which I don't want to do (yet) as i've just paid Covid tax for the car, which sent me broke... and its full of issues lol!

 

Cheers!

[Rusty Nuts]

Unfortunately that keyway is munted, it needs to be welded and re-cut thats the only true fix. That remnant of a key must have been causing timing issues. I would also pull the oil pump and check for damage. 

[CLEM0]

13 hours ago, Rusty Nuts said:

Unfortunately that keyway is munted, it needs to be welded and re-cut thats the only true fix. That remnant of a key must have been causing timing issues. I would also pull the oil pump and check for damage. 

Thanks for the reply mate- I figured that'd be the case- will try it with crank in car.

I don't think oil pump is going to be an issue as the balancer and the crank pulley are actually on seperate woodruff keys. The crank pulley is solid and doesn't seem to have any issues with the woodruff key, so I'm not sure if that'd affect the oil drive gear in any way. I have no oil pressure issues.

I am still curious if they key serves any purpose other than alignment- it doesn't seem like it could support any rotational force (aka why it died in the first place)

[NZ-GTT]

It looks like the timing belt was replaced and the crank bolt was not tightened enough. It is not easy to achieve the oem  152nm (RB25 & 30) torque spec with the engine in the car. this guy has got it sorted though: 

If it was my engine, I would replace the woodruff key and buy an ARP crank bolt, then tighten to their spec which is a lot tighter. From memory it was 250nm. Find TDC and mark it on the harmonic balancer. 

[trel]

6 hours ago, CLEM0 said:

Thanks for the reply mate- I figured that'd be the case- will try it with crank in car.

I don't think oil pump is going to be an issue as the balancer and the crank pulley are actually on seperate woodruff keys. The crank pulley is solid and doesn't seem to have any issues with the woodruff key, so I'm not sure if that'd affect the oil drive gear in any way. I have no oil pressure issues.

I am still curious if they key serves any purpose other than alignment- it doesn't seem like it could support any rotational force (aka why it died in the first place)

This happened on my old car, a repair was made, it lasted 6 months then my balancer wobbled everything loose, engine went bang. My experience, yours may vary depending how hard you drive it. Just know I wouldn't exactly be limiter bouncing.

[CLEM0]

1 hour ago, trel said:

This happened on my old car, a repair was made, it lasted 6 months then my balancer wobbled everything loose, engine went bang. My experience, yours may vary depending how hard you drive it. Just know I wouldn't exactly be limiter bouncing.

Well I guess that throws the theory that the key doesn't have pressure on it- what repair method did you use? And did you tighten the bolt to correct spec?

[CLEM0]

4 hours ago, NZ-GTT said:

It looks like the timing belt was replaced and the crank bolt was not tightened enough. It is not easy to achieve the oem  152nm (RB25 & 30) torque spec with the engine in the car. this guy has got it sorted though: 

If it was my engine, I would replace the woodruff key and buy an ARP crank bolt, then tighten to their spec which is a lot tighter. From memory it was 250nm. Find TDC and mark it on the harmonic balancer. 

That's what i'm thinking of doing. Going to patch up the keyway with weld bead, die grinder it smooth until the key fits well- loctite 660 as a means of removing any air gaps that can become dangerous under vibration, new balancer, new bolt, and torque the bolt to double factory specifications, probably with an ARP bolt. The way I see it, is I now need a new crank when I decide to rebuild, so I might as well give this a good shot.

I only just bought the car too! Man I wish these things were 5-10k still, shame I paid almost double, otherwise i'd have the engine out going forged right now if it was 10k! Wouldn't even fret the crank damage- i'd buy a new one haha!

 

I still can't figure out if the woodruff key actually does anything, or if the crank bolt high torque grips the balancer.
The woodruff key is mild steel so surely it can't take any rotational force- especially 400+ whp at 7k+ RPM, it must be the crank bolt. I'm not sure

[Ben C34]

no way are you going to be torquing it to double, thats either going to stretch and yield the bolt best case, or pull the crank thread out  (thats bad)

I agree the intial issue is likely caused by not having crank bolt tight enough. Plenty of engines dont have key on the crankshaft at all.

 

if it was me, and I didnt want to do it properly I would lean in on the dodginess and loctite the balancer on. Then in the future hate myself but thats future Ben's problem.

 

[trel]

9 hours ago, CLEM0 said:

Well I guess that throws the theory that the key doesn't have pressure on it- what repair method did you use? And did you tighten the bolt to correct spec?

Yeah we did loctite on it and tightened it her on HARD but still didn't hold, you must remember that it has an insane amount of force and vibration put on to it, again though your experience may vary, unfortunately in this situation the crank is for the bin imo.

[Rusty Nuts]

The reason I said check the oil pump is because; Your harmonic damper by definition is present to REDUCE vibration, yours has for some unknown period of time been ADDING vibration. RB oil pump drives have so much clearance new from the factory, they fail from limiter bashing and for careful drivers much later just because. Think about how much vibration bashing a hardened key almost in half caused. But I'm the President of the Do It Once Do It Right Brigade. If you are feeling too lazy, then you shouldn't be playing First Grade ,Bro

[Rusty Nuts]

11 hours ago, Ben C34 said:

if it was me, and I didnt want to do it properly I would lean in on the dodginess and loctite the balancer on. Then in the future hate myself but thats future Ben's problem.

Ah thats not full "dodge", Ya Gotta WELD that bastard on. Dry ice bags around the outer ring to stop the rubber delaminating and BADA BING, fixed full dodge. future Ben.

[GTSBoy]

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

[GTSBoy]

[BK]

It's not tight enough at all. I really don't know where this ridiculously low 150Nm torque setting comes from for an RB25 (I know it's "in the manual"). It is widely accepted that it is not adequate at under 200, when for the balancer on the RB26 torque is 440 - 466Nm. Even a 2JZ is torqued to a moderate 324Nm.

To quote myself from this thread about balancers:

 

 

11 hours ago, Ben C34 said:

no way are you going to be torquing it to double

Actually yeah you are. Here's some information to quote Darren Lewis from Lewis engines in SA who really does knows a thing or two about building an RB:

 

RB CRANK BOLT tensioning........

 Most often RB harmonic balancer bolts are not tightened correctly.We usually see crank snout damage from a loose balancer after a timing belt change where the mechanic ''thinks'' he has the bolt tight. The rb 25/30 bolt must be tightened to 400nm and the larger rb26 GTR bolt to 460 nm. The only way to tighten to this tension is by locking the flywheel in place with a suitable tool. Failure to do this , especially more so on a race RB30, will entail in balancer movement and in shortime balancer and or crank damage.

''happy times and keep it tight''............................Darren Lewis.

[CLEM0]

Thanks for the advice all.

I'm aware any way I fix this it's going to be bunky. As long as it lasts me until something else in the engine goes, then i'll be happy. I just paid nearly $20k for the car but I always planned to rebuild anyway, but not within a month of owning it!- I've had old cars before, they don't last forever.

I'm going to MIG weld the woodruff slot, file it down and get it as close as possible to a tight fit with the key. I'll put some loctite 660 (made for keyways) to fill any air gaps, grab a new balancer and put some antiseize on the crank bolt, and torque to 200-250nm. Anyone know a good method of locking the crank?

If anyone has any better ideas, i'd love to know. I'm pretty certain after some reading that the crank bolt is the reason the balancer stays tight- NOT the actual key. The key is simply for alignment purposes I don't care about the timing marks, just want to make sure everything stays put!

[BK]

3 minutes ago, CLEM0 said:

'm pretty certain after some reading that the crank bolt is the reason the balancer stays tight-

So, did you read anything I posted ? Like how Lewis engines recommend 400Nm on RB25 and RB30 because the standard recommended torque is stupid low ? You're balancer coming loose is the thing that's caused your dramas in the first place.

[CLEM0]

Just now, BK said:

So, did you read anything I posted ? Like how Lewis engines recommend 400Nm on RB25 and RB30 because the standard recommended torque is stupid low ? You're balancer coming loose is the thing that's caused your dramas in the first place.

I did but that's a bit risky with the stock bolt!

[BK]

Depends on what grade the OEM bolt is I guess. The RB25 uses a M16 bolt, not sure of the factory bolt grade though. With a new ARP M16 bolt would take it if you used one of those. I'm used to RB26s which are M18 and always use new a OEM bolt.

Anyway I hope you can fix it.

[CLEM0]

1 minute ago, BK said:

Depends on what grade the OEM bolt is I guess. The RB25 uses a M16 bolt, not sure of the factory bolt grade though. With a new ARP M16 bolt would take it if you used one of those. I'm used to RB26s which are M18 and always use new a OEM bolt.

Anyway I hope you can fix it.

Thank you mate. I'll grab an ARP bolt.

Hopefully i'm right assuming the bolt keeps the balancer on- not the key!

If that's the case, i'll just crank it tight and hope for the best.

Any good methods for flywheel locking with engine in car?

[BK]

3 minutes ago, CLEM0 said:

Thank you mate. I'll grab an ARP bolt.

Hopefully i'm right assuming the bolt keeps the balancer on- not the key!

If that's the case, i'll just crank it tight and hope for the best.

Any good methods for flywheel locking with engine in car?

That absolutely is the case. The bolt holds balancer on, key is just for locating position. As mentioned in the RB26 balancer torque thread, to lock the flywheel I use an old clapped out starter motor, cut up and welded locked.

There is actually a proper Nissan RB flywheel locking tool that bolts in the starter location, but getting one would be the trick.