Dial Indicator, need to check the runout on a crank

Chad Culbertson · **Posted:** Fri Nov 13, 2015 12:56 pm

Does anybody have a clamp on style dial indicator that would be suitable for check the runout on a crank nose?

I have a suspicion that the crank on the Miata is bent, I noticed the crank pulley wobbling when I was working on the AC so removed the pulley and the crank sensor ring so it wouldn't start. I shot some video of just the crank spinning while I cranked it and it looks a little wobbly to me. I think the only way to confirm is to use a dial indicator for sure. I'm really hoping it's not the case otherwise I just bought a car that needs a motor. It does run fine though but I would be suspect of it's reliability on track since who knows how long before a bearing lets go.

Here's a youtube link showing the crank nose turning while I turned it over.

https://youtu.be/rKZQLpl8Nh8?t=51

Richard Casto · **Posted:** Fri Nov 13, 2015 2:38 pm

Chad,

I have this tool if you want to borrow it...

http://www.harborfreight.com/clamping-d ... 93051.html

I live in the south Durham/RTP area (just south of I-40).

If you are into collecting tools, its not that expensive at HF and I have found it to be useful for a number of things.

Richard

Chad Culbertson · **Posted:** Fri Nov 13, 2015 3:35 pm

For that money and the frequency I need one its probably worth picking up. I actually have to drive out to Winston tomorrow anyway and I think there is one on the way.

Andrew Jonell · **Joined:** Mon Mar 23, 2009 6:43 pm **Posts:** 1350

You removed the (broken) damper. I'm not sure if it's even possible to bend a crank in a stock Miata.

Andrew from TSE's opinion is "probably not" on if it's possible that the crank is bent, but the dial indicator will tell you for sure.

Chad Culbertson · **Posted:** Fri Nov 13, 2015 4:08 pm

Andrew Jonell wrote:

You removed the (broken) damper. I'm not sure if it's even possible to bend a crank in a stock Miata.

Andrew from TSE's opinion is "probably not" on if it's possible that the crank is bent, but the dial indicator will tell you for sure.

I'm hoping that's the case, lol. Honestly the bolt head might be slightly off center and the gunk buildup might be playing some tricks on my vision and it spins.

I had to soak it good in WD-40 and use a rubber mallet and some prying to get the pulley off, so maybe if I hit it with a wire brush and clean it up and put the pulley back on it will be fine.

I have autocrosses the next two weekend and not really any time to mess with it before then anyway, so i'll probably clean it up and slap it back together in the mean time then once autocross is done I'll have some time to mess with it.

If the run out is good then i'll go buy me a new pulley/balancer. Since the pulley is $152 bucks it makes sense to me to make sure before I spend that money.

FrancisChan · **Posted:** Fri Nov 13, 2015 5:15 pm

Once you have 2 autocross events you can join the Mazdaspeed motorsports parts program and get a discount on replacement parts.

$115.71 for a crank pulley

Chad Culbertson · **Posted:** Fri Nov 13, 2015 7:02 pm

FrancisChan wrote:

Once you have 2 autocross events you can join the Mazdaspeed motorsports parts program and get a discount on replacement parts.

$115.71 for a crank pulley

Yep, i've been informed about Mazdaspeed.

I didn't realize that the boss that the pulley bolts to isn't actually the crank nose. I took the crank bolt out and pulled the boss off and cleaned things up so they fit back together cleanly. Also put some anti-seize on there so it's not so tough to get the pulley off again.

There's no way the crank bolt was torqued to 120 ft lbs, I pop it off no sweat with a 21mm box end wrench without much effort.

The dang sway bar was in the way and I couldn't get my torque wrench on the bolt so I used my box end and a cheater bar and tried to get it fairly tight. I really need to get the holding tool though because I doubt getting a good torque is very easy by just leaving the car in 5th gear.

I'm betting if anything it would be the boss that isn't true or the pulley, or the bolt not being torqued to spec might be an issue also. I didn't start it back up since I move immediately to the next clunker ripping water pump and radiator out lol. I just needed it back together for the weekend, so if it's still wobbly i'll look into a new pulley.

Aaron Buckley · **Posted:** Fri Nov 13, 2015 7:57 pm

FrancisChan wrote:

Once you have 2 autocross events you can join the Mazdaspeed motorsports parts program and get a discount on replacement parts.

$115.71 for a crank pulley

You can join before you ever race your car. You just need to tell them you are doing a build, they'll send you the decals and request you take a picture of your car with the decals in the right position and numbers on it (even on jack stands without wheels on it). They'll request that you get them 2 race results within the next 12 months, but you can order parts at the discount right away. - AB

Richard Casto · **Posted:** Fri Nov 13, 2015 8:18 pm

Was thinking that the HF tool is on sale right now at a good price and might be out of stock. You might call before driving out of your way to visit a store. If that is the case feel free to PM me if you want to borrow mine.

Richard

JamesMilko · **Posted:** Fri Nov 13, 2015 9:47 pm

You only need decals for contingency. Results within 12 months is all you need for the parts program.

Chad Culbertson · **Posted:** Sat Nov 14, 2015 12:37 am

I have one under my belt and running the TSCC event in GSO this Sunday, so i'll have the 2 timed events come this weekend anyway.

Chad Culbertson · **Posted:** Sat Nov 14, 2015 12:39 am

Richard Casto wrote:

Was thinking that the HF tool is on sale right now at a good price and might be out of stock. You might call before driving out of your way to visit a store. If that is the case feel free to PM me if you want to borrow mine.

Richard

Thanks, it's literally right on my way into/from Winston-Salem anyway, so if they don't have any i'll hit you up. Thanks for the heads up.

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Dial Indicator, need to check the runout on a crank

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