B6/BP crankshaft pulley void filler?

[takai]

Every time i look behind the crankshaft bolt on one of these a little more of the engineer inside me dies:


That void and the fact that some engineer decided it was a good idea to mount the harmonic balancer/crank pulley off a 5mm shoulder of crank snout:


Like seriously?

Anyway, was thinking that one of the possible remedies (at least for my inner engineer) is to machine a secondary filler up to give the woodruff key a greater mounting surface. That way if it does get out of round it shouldnt wobble and destroy the crank snout.

Surely someone has already done this? Anyone know of something?

Also, bonus pic of what a properly designed crank snout looks like:

[ralt]

hi.
So?

[StillIC]

I recall finding a website selling the exact solution you imagine. It was USA based. I figured it was an unnecessary purchase due to the fact that the part doesn't fail (on big nosed cranks).

[takai]

I recall finding a website selling the exact solution you imagine. It was USA based. I figured it was an unnecessary purchase due to the fact that the part doesn't fail (on big nosed cranks).

Yeah, it doesn't fail on big noses


Ive been googling for a while now, havent found anyone selling it. If you find one let me know.

[hks_kansei]

Compare the few failures to the total number of B6 and BP engines made.
Hell, even just compare the failures to the total number of B6/Bp in the MX5 models alone.

That's probably why there's no options ready made, it's not really necessary in most cases, and Mazda probably knew this.

Why engineer something to be 100% bulletproof if it's never going to be shot at?

[ralt]

Hi.
Yes there was a kit available from the us used a longer key and extension. Bought one for a friend who fitted it and no further problems. I first saw it mentioned on the big forum with the link to ebay usa.

[takai]

Compare the few failures to the total number of B6 and BP engines made.
Hell, even just compare the failures to the total number of B6/Bp in the MX5 models alone.

That's probably why there's no options ready made, it's not really necessary in most cases, and Mazda probably knew this.

Why engineer something to be 100% bulletproof if it's never going to be shot at?

Serious? It is a known issue that they completely changed the bottom end configuration to 'resolve.' It is patently obvious that it was an issue, given that they bothered to change it and produce an entirely separate interchange crank (long nose) in case of warranty failure.

Only they didnt resolve it on the big nose, they just increased the clamping pressure slightly and shifted the pivot point forward of the timing belt pulley.

They had an opportunity to do so when they changed the crank entirely for the different bore spacing on the BP, but they just stuck their head in the sand and didnt do a thing.

[takai]

Hi.
Yes there was a kit available from the us used a longer key and extension. Bought one for a friend who fitted it and no further problems. I first saw it mentioned on the big forum with the link to ebay usa.

Bingo. The key word here is "extension" which turns it up on Google. http://www.justmiata.net/shop

The signal to noise ratio on 'key' is just too high.

[hks_kansei]

Serious? It is a known issue that they completely changed the bottom end configuration to 'resolve.' It is patently obvious that it was an issue, given that they bothered to change it and produce an entirely separate interchange crank (long nose) in case of warranty failure.

Only they didnt resolve it on the big nose, they just increased the clamping pressure slightly and shifted the pivot point forward of the timing belt pulley.

They had an opportunity to do so when they changed the crank entirely for the different bore spacing on the BP, but they just stuck their head in the sand and didnt do a thing.

While I agree that the early B6 setup obviously had issues, my point is that I believe much of these issues to have been exaggerated.

While faults do occur, with how many people carry on about them on forums (mainly Miata.net) you'd think that every second MX5 has the front of the crank shear off.
In actual fact the numbers are far, far lower. (i know it's anecdotal rather than any kind of real data, but of the many, many, many MX5 owners i've met and known both locally and on the forums, I know of maybe 2 NA6s that have had a full failure, and a few more that removed an engine because the pulley "looked" like it had a wobble, and only know of a single BP that's lost the keyway)


A lot probably comes down to our different professions, you've mentioned your an engineer, so you're just looking at the best way to make something.

I'm an accountant, i'm also taking into account that the best way isn't always necessary, sometimes the best value way is the most useful option, which is what I suspect Mazda chose (cost to fully remove the damage risk, vs lowering the risk substantially for less cost)

[ralt]

Hi.
Just to give you all an idea of the problems mazda had with the short nose crank. This crank was not only an mx5 problem but every 1.6 engine they built. Many years ago i met a man who had an interesting story to tell regarding 1.6 engines. He was bringing in engines and parts from japan and was constantly being asked for mazda 1.6 crankshafts only. Being very savvy he started bringing in secondhand cranks as mazda new were to expensive and they could not keep up the supply if you wanted a new one. He told me he had imported over 1000 cranks and very profitable.

[takai]

Serious? It is a known issue that they completely changed the bottom end configuration to 'resolve.' It is patently obvious that it was an issue, given that they bothered to change it and produce an entirely separate interchange crank (long nose) in case of warranty failure.

Only they didnt resolve it on the big nose, they just increased the clamping pressure slightly and shifted the pivot point forward of the timing belt pulley.

They had an opportunity to do so when they changed the crank entirely for the different bore spacing on the BP, but they just stuck their head in the sand and didnt do a thing.

While I agree that the early B6 setup obviously had issues, my point is that I believe much of these issues to have been exaggerated.

While faults do occur, with how many people carry on about them on forums (mainly Miata.net) you'd think that every second MX5 has the front of the crank shear off.
In actual fact the numbers are far, far lower. (i know it's anecdotal rather than any kind of real data, but of the many, many, many MX5 owners i've met and known both locally and on the forums, I know of maybe 2 NA6s that have had a full failure, and a few more that removed an engine because the pulley "looked" like it had a wobble, and only know of a single BP that's lost the keyway)


A lot probably comes down to our different professions, you've mentioned your an engineer, so you're just looking at the best way to make something.

I'm an accountant, i'm also taking into account that the best way isn't always necessary, sometimes the best value way is the most useful option, which is what I suspect Mazda chose (cost to fully remove the damage risk, vs lowering the risk substantially for less cost)

As an accountant then consider whether it is worth redesigning an entire crank because of failures if it is exaggerated? Mazda did exactly that, building a long nose crank (not the big nose one) to replace the short nose under warranty failures. The fact that they did this would suggest—even from a monetary perspective—that it was a pretty big issue.

[Mr Morlock]

HKS had a really good point- whilst the problem required a re design, as far as I know it did not result in a recall and many folks are still driving early NAs without a failure. This problem pales compared to the follies of many other manufacturers. Mazda fixed it. We have modern cars with dodgy dsg's and one maker of a certain German fast car that built a engine with a serious flaw that killed many engines and it took them years to fix it and an appalling oversight in design and testing. Whilst it is a known fault - the NA long crank - its also true that the MX-5 has an excellent reputation as a competent and reliable car.

[PhilM]

The short nose crank length is an example of poor design and if it had been done correctly there would have been zero failures making the B6 engine completely reliable and not needing this post.

[StillIC]

The short nose crank length is an example of poor design and if it had been done correctly there would have been zero failures making the B6 engine completely reliable and not needing this post.

Phil, Takai is asserting big nosed crank failure(s). If true I wonder what has caused it. Is it poorly designed too?

[takai]

HKS had a really good point- whilst the problem required a re design, as far as I know it did not result in a recall and many folks are still driving early NAs without a failure. This problem pales compared to the follies of many other manufacturers. Mazda fixed it. We have modern cars with dodgy dsg's and one maker of a certain German fast car that built a engine with a serious flaw that killed many engines and it took them years to fix it and an appalling oversight in design and testing. Whilst it is a known fault - the NA long crank - its also true that the MX-5 has an excellent reputation as a competent and reliable car.

Dont equate no recall with no problem, plenty of manufacturers in the 90s didnt recall cars with severe engine issues because they would only come about after the end of the warranty period.

Toyota had every single 7MGE in Australian built MX83 Cressida's go out from the factory with the head studs under torqued, every single one BHGed. No recall.
Nissan YD25s have a severe oil pump problem that causes regular failures.
etc
etc

It is only with the slowing auto sales market and the longer warranties that we are seeing recalls happen with any regularity.

The short nose crank length is an example of poor design and if it had been done correctly there would have been zero failures making the B6 engine completely reliable and not needing this post.

Phil, Takai is asserting big nosed crank failure(s). If true I wonder what has caused it. Is it poorly designed too?

Im not asserting it, look at the photo. Crank sensor and failed keyway.
It is still a bad design, that they "fixed" by increasing the clamping force on the pulley boss slightly through the larger diameter shoulder bolt.

The fact that there is a massive void under half the woodruff key means that as soon as that bolt loosens the woodruff key can walk into the void and the subsequent wobble will tear the snout apart. Compare that to other engines which have no issues, even when they lose the pulley bolt entirely.