Aug 8, 2017 update to the Mazda Miata project car

Project Turbo Miata: Investigating Our Differential Failure

Many hands make light work—except, of course, when they make more work. Such was the case with our project turbo Miata’s mysteriously locked rear wheels. After skidding off track during our test day at Talladega Gran Prix Raceway, we towed the car home to figure out why the wheels weren’t turning anymore. Stretch goal: Unlock them so we could roll the poor car off the trailer.

The answer, as it turns out, was user error. You’ve probably noticed in our updates that we’ve had a lot of hands on our car. It’s great to have additional help, but at some point a helper drained the differential fluid, then forgot to refill it. We were running on track with a nearly-dry rear differential, and it eventually heated up so much that the pinion gear fused with the ring gear, locking the rear wheels completely.

Oops. Time to go find a new differential!

Watch the pages of Grassroots Motorsports for the full project car series. Subscriptions start at just $10.

Join Free Join our community to easily find more project updates.

Comments

View comments on the GRM forums
noddaz
noddaz SuperDork
8/8/17 4:11 p.m.

This is one of the things I like about GRM. When someones screws up there is no sugar coating it. You learn from it. You fix it. And you move on. Real life racing.

zordak
zordak New Reader
8/10/17 9:36 a.m.

A good reason to check all fluid levels at the track before going out.

Cotton
Cotton UberDork
8/10/17 9:39 a.m.

I like that trailer.

Rufledt
Rufledt UberDork
8/10/17 9:44 a.m.
Cotton wrote: I like that trailer.

I was just thinking that.

Knurled
Knurled MegaDork
8/10/17 7:14 p.m.

This is why I scream at people who drain oil out of something and then don't fill it right away.

You will get distracted. You will get pulled away. You will forget. Maybe not this time, maybe not the next time, but one time you WILL win that particular lottery.

calteg
calteg Dork
8/10/17 7:49 p.m.
Knurled wrote: This is why I scream at people who drain oil out of something and then don't fill it right away. You will get distracted. You will get pulled away. You will forget. Maybe not this time, maybe not the next time, but one time you WILL win that particular lottery.

Sticky note on the steering wheel solves this.

"Fluids, dummy"

You'll know which one.

Stampie
Stampie SuperDork
8/10/17 8:08 p.m.
Rufledt wrote:
Cotton wrote: I like that trailer.

I was just thinking that.

I was eyeballing it real close recently. It's even nicer in person.

BrokenYugo
BrokenYugo MegaDork
8/10/17 8:40 p.m.

This is another reason to always pull the fill plug first.

Keith Tanner
Keith Tanner MegaDork
8/10/17 8:42 p.m.
calteg wrote:
Knurled wrote: This is why I scream at people who drain oil out of something and then don't fill it right away. You will get distracted. You will get pulled away. You will forget. Maybe not this time, maybe not the next time, but one time you WILL win that particular lottery.

Sticky note on the steering wheel solves this.

"Fluids, dummy"

You'll know which one.

After I took a turbo car out when it was running a naturally aspirated tune, we started using "NOT IN SERVICE" tags.

MrJoshua
MrJoshua UltimaDork
8/10/17 8:49 p.m.

Lol-The teammates must have asked each other "Did you check the fluid in the diff?" about 5 times during the autocross portion of the'08 Challenge (When the Mumpkin was still the Husband Wife build). The answer was: no, no we didn't check the fluid in the diff. It would have been best to check because we had apparently never refilled the diff. We continued to not check the fluid in the diff until it locked up at the top end of the strip after about the 20th drag run. I'm impressed it lasted so long. Ours seized the pinion bearing.

Joe Gearin
Joe Gearin Associate Publisher
8/11/17 10:03 a.m.
Cotton wrote: I like that trailer.

The trailer does kick ass. We've had it for years now, and it's travelled thousands of miles and hauled countless projects around the country. We got it from Trailer World in Kentucky, and we can't recommend it enough!

Trailer World

Following the spirit of this thread........ I recently towed the crapcan Miata, and forgot to securely plug-in the trailer lights. Well, the receptacle came loose, got dragged on the pavement and was ruined. Re-wiring the trailer should have been a breeze...... universal receptacles have wires that match the commonly used trailer wires right? Wrong! Lucky me--- I got to spend a few hours tracking down the correct leads and re-wiring the lights for our lovely trailer. So yes......we screw up, just like the rest of you do!

GTXVette
GTXVette Dork
8/11/17 10:17 a.m.

we kept it simple, the plug(name your part) is IN Or OUT. rear, tranny, or engine.NEVER screw one in and leave it for later But we would Nut and Bolt check before loading up too.

WonkoTheSane
WonkoTheSane Dork
8/11/17 11:05 a.m.

I've been a fan of putting the bottle of fluid on the drivers seat. If you want to move the car or start it, you have to sit on or move the fluid.

codrus
codrus UltraDork
8/11/17 11:35 a.m.
WonkoTheSane wrote: I've been a fan of putting the bottle of fluid on the drivers seat. If you want to move the car or start it, you have to sit on or move the fluid.

Yeah, this is my usual shortcut technique. I do the same with the torque wrench if there's stuff I need to torque. :)

Tom Suddard
Tom Suddard Associate Editor
8/11/17 12:14 p.m.

Yeah, totally. I still don't know who drained it, actually, or when.

WonkoTheSane
WonkoTheSane Dork
8/11/17 12:38 p.m.
Tom Suddard wrote: Yeah, totally. I still don't know who drained it, actually, or when.

I'll bet whoever did it knows and is feeling pretty bad right about now...

Snrub
Snrub Reader
8/11/17 12:44 p.m.

^ I wouldn't have the courage to post and tell the world this happened to my car.

Sponsored by

Bridgestone

DIYAutoTune

Treasure Coast Miata

SPA Technique

Advanced Autosports

Energy Suspension

Fuel Injector Clinic

Konig Wheels

Nerdie Racing

Safecraft

Speed Seat Factory

Very Cool Parts

Our Preferred Partners
A4jJ9WIrx17GU4keVvMPnCBz0tnwM5lc