Why are these extension housing bolts sheared? - Page 2 - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members

Suspension, Brakes, Drivetrain discuss the wondrous effects of boost and your miata...

LinkBack Thread Tools Search this Thread
Old 09-19-2013, 02:44 PM   #21
Elite Member
iTrader: (2)
fooger03's Avatar
Join Date: Jan 2009
Location: Columbus, OH
Posts: 4,132
Total Cats: 187

My vote is for missing dowel pins allowing the tranmission to rotate relative to the block under power. The bolts which hold the transmission to the block using compression are not designed to prevent the two rotating against each other under torque. In fact, the bolts fit so losely through the transmission side holes before engaging in the engine side threads that I wouldn't put it past the engineers to have designed the part such that the shank of the bolt doesn't touch the inside of the bolt holes on the bellhousing. The dowel pins are designed to be nearly press-fit which virtually eliminates torque hammer between the two parts.
fooger03 is offline   Reply With Quote
Old 09-20-2013, 10:12 AM   #22
iTrader: (11)
sixshooter's Avatar
Join Date: Nov 2008
Location: Tampa, Florida
Posts: 15,662
Total Cats: 1,560

I have seen similar failures on heavy machinery due to an under torqued condition. It allows a shock load to break a bolt in a way that hundreds of pounds of torquing could not accomplish. But I could be wrong in this instance. All I can do is speculate.
sixshooter is offline   Reply With Quote
Old 09-22-2013, 06:32 PM   #23
Senior Member
iTrader: (1)
Join Date: Oct 2009
Posts: 1,436
Total Cats: 58

After a quick flip through your build page, it looks like you've got a very stiff chassis with very little flexibility. A system can be over-restrained to the point that it becomes 'infinitely rigid' compared to the components it connects to. When this happens, loads get redistributed to the least rigid components and it leads to failure. I'd like to say that you're chassis is so stiff that the lack of chassis/ppf flex put excessive tension on the bolts and failed them.
Enginerd is offline   Reply With Quote
Old 08-25-2017, 10:01 PM   #24
Join Date: Aug 2017
Posts: 1
Total Cats: 0

Any update to this #Laur3ns? I know this is an old tread but what did you end up finding out? and doing about it? I have the same issue
Matt Williamson is offline   Reply With Quote
Old 08-26-2017, 02:51 PM   #25
Elite AbsurdFlow Member
Thread Starter
Laur3ns's Avatar
Join Date: Mar 2008
Location: Enschede, NL
Posts: 2,058
Total Cats: 11

Dowel pins were not missing of course. Some 12.9 replacement bolts have taken care of this issue.

There is a guy in the UK who went through the same story and it worked for him too. Quaife apparently now includes better bolts in their gearset.
Laur3ns is offline   Reply With Quote

Related Topics
Thread Thread Starter Forum Replies Last Post
Another Cast Manifold Corky Bell Prefabbed Turbo Kits 18 11-22-2016 10:01 PM
Need help - Stock Balancer and Fastforward overlay pulleys Frank_and_Beans Supercharger Discussion 13 09-12-2016 09:17 PM
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
WTB Bellhousing Bolts patsmx5 WTB 1 10-01-2015 10:43 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 05:27 AM.