Broken diff housing - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


Race Prep Miata race-only chat.
Sponsored by:
Sponsored by:

Reply
 
 
 
LinkBack Thread Tools Search this Thread
Old 08-25-2013, 02:42 PM   #1
Elite Member
Thread Starter
 
Join Date: Jul 2005
Location: Anacortes, WA
Posts: 2,476
Total Cats: 114
Default Broken diff housing

I put my car up on the lift and happened to notice this. Diff arm cracked right through the machined in break here feature. I hadn’t noticed anything weird but from the fracture surface it doesn’t look like it was broken all the way through for very long. Might have broken my last autocross run last weekend and I just happened to see it. Anybody else breaking these? I cringe every time I see people jacking up there car by the diff and It is something I’ve never done.

Attached Thumbnails
Broken diff housing-20130824_105354-2-1024x768-.jpg   Broken diff housing-20130824_154834-2-1024x768-.jpg  
bbundy is offline   Reply With Quote
Old 08-25-2013, 02:45 PM   #2
Junior Member
 
Join Date: Sep 2012
Posts: 73
Total Cats: 0
Default

Many break there, thats why everyone uses the FC housings. P.S. I have some for sale!
pitobread is offline   Reply With Quote
Old 08-25-2013, 03:14 PM   #3
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,872
Total Cats: 1,790
Default

jacking by the diff isn't going to do that.

but that's a factory break point so you don't ruin the motor/drivetrain on a rear end collision
Braineack is offline   Reply With Quote
Old 08-25-2013, 03:20 PM   #4
Elite Member
Thread Starter
 
Join Date: Jul 2005
Location: Anacortes, WA
Posts: 2,476
Total Cats: 114
Default

Quote:
Originally Posted by pitobread View Post
Many break there, thats why everyone uses the FC housings. P.S. I have some for sale!
Will those fit the Miata front section? I might be interested.
bbundy is offline   Reply With Quote
Old 08-25-2013, 03:22 PM   #5
I'm a terrible person
iTrader: (19)
 
FRT_Fun's Avatar
 
Join Date: Apr 2009
Location: Arizona
Posts: 7,293
Total Cats: 180
Default

Yes. When I swapped in my RX7 clutch diff I used the 7 housing/ring and the miata nose/pinion.



Attached Thumbnails
Broken diff housing-photo15k.jpg   Broken diff housing-22050820395625868481177.jpg  
FRT_Fun is offline   Reply With Quote
Old 08-25-2013, 03:23 PM   #6
Elite Member
Thread Starter
 
Join Date: Jul 2005
Location: Anacortes, WA
Posts: 2,476
Total Cats: 114
Default

Quote:
Originally Posted by Braineack View Post
jacking by the diff isn't going to do that.

but that's a factory break point so you don't ruin the motor/drivetrain on a rear end collision
I never Jack by the Diff. I was surprised seeing 949 racing jacking by the diff at the 25 hours of Thunderhill.

FWIW looks like the crack initiated at the top slot.
bbundy is offline   Reply With Quote
Old 08-25-2013, 03:35 PM   #7
Elite Member
Thread Starter
 
Join Date: Jul 2005
Location: Anacortes, WA
Posts: 2,476
Total Cats: 114
Default

Wow not only does the RX7 one not have a notch and looks beefier its got a big flat spot that looks like it was made to be a jack point.
bbundy is offline   Reply With Quote
Old 08-25-2013, 03:44 PM   #8
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,872
Total Cats: 1,790
Default

Quote:
Originally Posted by bbundy View Post
I never Jack by the Diff.
factory manual shows it as a jacking point.

Quote:
Originally Posted by bbundy View Post
Wow not only does the RX7 one not have a notch and looks beefier its got a big flat spot that looks like it was made to be a jack point.
yep. no notches, and MUCH beefier "legs"
Braineack is offline   Reply With Quote
Old 08-25-2013, 05:55 PM   #9
Senior Member
iTrader: (14)
 
Join Date: Jan 2007
Location: Murfreesboro,TN
Posts: 1,277
Total Cats: 53
Default

Quote:
Originally Posted by bbundy View Post
Wow not only does the RX7 one not have a notch and looks beefier its got a big flat spot that looks like it was made to be a jack point.
I was thinking about selling one I received a few weeks ago. Shoot me a PM if you can't procure one locally. If not, I might just keep it as a spare now knowing its a little stronger.
Midtenn is offline   Reply With Quote
Old 08-25-2013, 08:10 PM   #10
Senior Member
iTrader: (1)
 
Join Date: Jan 2011
Location: Chattanooga, Tn
Posts: 1,038
Total Cats: 157
Default

Went through two at a pro solo last month.

Attached Thumbnails
Broken diff housing-1014014_10151682231989242_1360985053_n_zps32da6509.jpg  
TNTUBA is offline   Reply With Quote
Old 08-25-2013, 09:53 PM   #11
Newb
 
Join Date: Apr 2011
Posts: 1
Total Cats: 0
Default

I broke mine exactly like that with my f20c. I didn't **** around with it I'm ordering boosfrog 8.8 diff bracket tomorow
J-pp is offline   Reply With Quote
Old 08-25-2013, 11:12 PM   #12
Elite Member
iTrader: (1)
 
Leafy's Avatar
 
Join Date: Jun 2012
Location: NH
Posts: 9,093
Total Cats: 90
Default

The Rx7 one looks heavier. If I find it to be a problem on my car I'll fully box the arms and send it out to be re-heat treated.

I'm not sure how people jack by the diff. Even with my super long reach ultra low HF racing jack I cant reach it, the jack hits the stock 94+ "cannon brace" before I get in far enough. When I jack the rear I jack from the rear most bolt of that brack. Hasn't bent anything yet.
Leafy is offline   Reply With Quote
Old 08-26-2013, 12:22 AM   #13
Senior Member
iTrader: (18)
 
Join Date: May 2008
Location: Big Bear Ca
Posts: 990
Total Cats: 8
Default

I've seen two like that. Sporting the RX-7 one now.
dstn2bdoa is offline   Reply With Quote
Old 08-26-2013, 01:21 AM   #14
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,366
Total Cats: 1,326
Default

Theseus has had an FC housing for a few years now.
Savington is online now   Reply With Quote
Old 08-26-2013, 02:07 AM   #15
Senior Member
 
Join Date: Dec 2010
Location: Auckland, NZ
Posts: 783
Total Cats: 23
Default

What causes these failures, axle tramp...hoosiers......+300 WHP...Auto X only?

Having built and continuing to develop my circuit racing car. I am interested to know if this is something that should be on my radar or not?
mx5-kiwi is offline   Reply With Quote
Old 08-26-2013, 02:38 AM   #16
Elite Member
Thread Starter
 
Join Date: Jul 2005
Location: Anacortes, WA
Posts: 2,476
Total Cats: 114
Default

Quote:
Originally Posted by mx5-kiwi View Post
What causes these failures, axle tramp...hoosiers......+300 WHP...Auto X only?

Having built and continuing to develop my circuit racing car. I am interested to know if this is something that should be on my radar or not?
Well I'm guessing in my case over 300 ft-lbs of torque 275 A6 Hoosiers and I recently did a bunch of autocross. western states champ win Packwood Prosolo win and Canadian National Autoslolom championship win in SSM also having a co-driver. The energy suspension diff mounts may not be as nice to this part as well.

So I Guess I found another weak point. I have already determined the inner CVs wear out fairly rapidly. About half a season and the ***** imbed themselves into the outer cup and they start developing lots of slop. I suspect Mazdaspeed axles would fix that.
bbundy is offline   Reply With Quote
Old 08-26-2013, 02:46 AM   #17
Senior Member
iTrader: (6)
 
Join Date: Jun 2010
Location: San Rafael, CA
Posts: 1,125
Total Cats: 41
Default

Given the location of the relief notches the housing must be snapping from front to rear movement of the drive train. What kind of motor mounts are you guys who broke em running?

Would something like this help?

Joy Fast PPF performance bars - MiataRoadster - High-performance customer service...and parts for Roadsters

It would stop the twisting and front to rear movement of the drive train.
k24madness is offline   Reply With Quote
Old 08-26-2013, 07:55 AM   #18
Senior Member
 
Join Date: Dec 2010
Location: Auckland, NZ
Posts: 783
Total Cats: 23
Default

I have one of those but a Beatrush one. I bought it to try and alleviate axle tramp in the damp conditions of my first race but quickly took it off becaues in the wet the transition from grip to no grip was instant and undetectable, on the road....frightening. Can't imagine it being better on the track..

I do wonder if it is an improvement to the standard setup in the dry though....in for anyones experiences....

I haven't had a chance to do a back to back test, due to combination of building car and the wet winter has prevented much driving/testing....but intend to at some point.
mx5-kiwi is offline   Reply With Quote
Old 08-26-2013, 08:38 AM   #19
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,872
Total Cats: 1,790
Default

Quote:
Originally Posted by Leafy View Post
The Rx7 one looks heavier. If I find it to be a problem on my car I'll fully box the arms and send it out to be re-heat treated.

I'm not sure how people jack by the diff. Even with my super long reach ultra low HF racing jack I cant reach it, the jack hits the stock 94+ "cannon brace" before I get in far enough. When I jack the rear I jack from the rear most bolt of that brack. Hasn't bent anything yet.

sounds like someone belongs in the CR slammed thread.
Braineack is offline   Reply With Quote
Old 08-26-2013, 01:52 PM   #20
Elite Member
Thread Starter
 
Join Date: Jul 2005
Location: Anacortes, WA
Posts: 2,476
Total Cats: 114
Default

Quote:
Originally Posted by k24madness View Post
Given the location of the relief notches the housing must be snapping from front to rear movement of the drive train. What kind of motor mounts are you guys who broke em running?

Would something like this help?

Joy Fast PPF performance bars - MiataRoadster - High-performance customer service...and parts for Roadsters

It would stop the twisting and front to rear movement of the drive train.
AWR engine mounts energy suspension Diff mounts. I suspect the failure is more related to torque reaction. High input of engine torque puts the top flange where the notch is in tension. From the fracture surface I can see evidence of periodic crack growth from the top notch over time about half way through the part then snap from the lower notch.
bbundy is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Back to Stock Part Out!! Turbo Parts, MS2 Enhanced 01-05, Suspension, and MOAR! StratoBlue1109 Miata parts for sale/trade 16 10-02-2015 10:39 AM
Another Alternator thread ihiryu General Miata Chat 9 09-28-2015 11:22 AM
Stripped clutch slave bell housing threads. EricJ Suspension, Brakes, Drivetrain 6 09-13-2015 10:44 PM
Hi turbo kitten nelson8708 Meet and Greet 11 09-06-2015 10:49 AM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 02:51 AM.