BOLTS WONT STOP BREAKING! - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


Engine Performance This section is for discussion on all engine building related questions.
Sponsored by:
Sponsored by:

Reply
 
 
 
LinkBack Thread Tools Search this Thread
Old 03-09-2014, 10:45 AM   #1
Newb
Thread Starter
 
Join Date: Nov 2013
Location: NY longisland
Posts: 16
Total Cats: 0
Default BOLTS WONT STOP BREAKING!

Whats up guys.
Im finally putting my engine back together and i was putting the cams in whennn a cam cap bolt snapped off in the block.
After cursing and crying i got it out of the head with a reversed thread drill bit
Went down to mazda and 2 days later i have an oem bolt. Sweet!
Now lets just get this done and over with right?

NO! another old bolt breaks off in the head and i rage quit and walk away

I need to go back and get another bolt but i was wondering guys...

Is there some tricks to make old bolts a bit stronger maybe?
My thought is i could maybe warm them a bit before attempting to get this damn cam bolted in and hopefully they'll just stretch a bit before breaking?
shaun is offline   Reply With Quote
Old 03-09-2014, 10:50 AM   #2
Slowest Progress Ever
iTrader: (26)
 
thirdgen's Avatar
 
Join Date: Oct 2007
Location: The coal ridden hills of Pennsylvania
Posts: 5,806
Total Cats: 183
Default

What are you torquing them at? Make sure your torque wrench is for inch / lbs and not ft/ lbs. If your manual says something like 30 inch /lbs and you set your torque wrench for 30 ft/lbs (cause you though it was an inch lbs wrench) then obviously you'll be wayyyy over tightening your bolts, thus causing them to break.
If that's not the case, buy all brand new bolts.
thirdgen is offline   Reply With Quote
Old 03-09-2014, 11:20 AM   #3
Elite Member
iTrader: (21)
 
Join Date: Jun 2007
Location: Rochester, NY
Posts: 5,684
Total Cats: 555
Default

You should run a tap through the threads in the block before rebuilding, to clean up any buggered threads. Make sure to flush out the chips completely. Discard any rusty bolts, or ones with messed up threads.

But I agree, you are probably way over-torqueing those bolts.
rleete is offline   Reply With Quote
Old 03-09-2014, 11:59 AM   #4
Newb
Thread Starter
 
Join Date: Nov 2013
Location: NY longisland
Posts: 16
Total Cats: 0
Default

The first time I was using an inch lbs wrench and I think it was 45 but the second time around I was just getting them tight by hand with a wrench and it wasn't very tight, just enough till they stopped moving. Was just giving them all a last check and added a little more to one and it popped.

Im not asking what im doing wrong im just asking if i can strengthen them without buying all new bolts cause that'll get expensive lol
shaun is offline   Reply With Quote
Old 03-09-2014, 12:12 PM   #5
Junior Member
 
Join Date: Jan 2014
Location: Madison
Posts: 153
Total Cats: 7
Default

Been there. Prior owner over torqued most of the hardware required to do the last tb/wp job. Nothing went back in to torque spec - it either stretched or broke.

Replace the hardware.
jt@namiata.com is offline   Reply With Quote
Old 03-09-2014, 12:20 PM   #6
Elite Member
iTrader: (3)
 
concealer404's Avatar
 
Join Date: Aug 2011
Posts: 8,465
Total Cats: 782
Default

And make sure you're not bringing the cam in where it's supposed to be WITH the bolts.
concealer404 is online now   Reply With Quote
Old 03-09-2014, 12:49 PM   #7
Cpt. Slow
iTrader: (25)
 
curly's Avatar
 
Join Date: Oct 2005
Location: Oregon City, OR
Posts: 12,107
Total Cats: 518
Default

I'm not quite sure how you're supposed to compress the cam without using the bolts. I always have...

Sounds like another person over torqued the bolts. Check all of them for necking and replace.

Attached Thumbnails
BOLTS WONT STOP BREAKING!-livigno112.jpg  
curly is offline   Reply With Quote
Old 03-09-2014, 02:50 PM   #8
Elite Member
iTrader: (3)
 
concealer404's Avatar
 
Join Date: Aug 2011
Posts: 8,465
Total Cats: 782
Default

I'm not saying don't compress it with the bolts...

I'm saying don't bring the cam down in the journals with the bolts. Like... an inch out or whatever.

I cringe every time i see that.
concealer404 is online now   Reply With Quote
Old 03-10-2014, 08:14 PM   #9
Elite Member
iTrader: (4)
 
Join Date: Sep 2006
Location: Charlotte, NC
Posts: 3,049
Total Cats: 5
Default

Make sure the bolts are dry as are the threads you are torquing them into as well. Any sort of lubricant/oil will significantly affect the friction coefficient of the bolted joint, transferring more tensile load into the bolt for the same amount of torque applied to it.

That is, you can pop m6 bolts if you are torquing them when they are oily. The oil lessons the friction in the threads and transfers all of the torque as bolt load and over stresses the fastener. This condition is worsened if the bolt has already been over-torqued (ie already plastically deformed).

So, were they oily/wet at all?

Last edited by Efini~FC3S; 03-10-2014 at 08:15 PM. Reason: Redundant "are" removal
Efini~FC3S is online now   Reply With Quote
Old 03-10-2014, 11:03 PM   #10
Senior Member
iTrader: (3)
 
Join Date: Dec 2011
Location: Tucson, Az
Posts: 514
Total Cats: 33
Default



Odds are a PO or a grease monkey with gorilla arms overtorqued them all.

Hmm. Could one install studs and used flanged nuts to avoid stressing the threads in the delicate aluminum head? Boltdepot has 14.9 grade M6 "set screws" in lengths from 8 to 50 mm and 10.9 flanged hex nuts to match.
Attached Thumbnails
BOLTS WONT STOP BREAKING!-139149.jpg  
TheScaryOne is offline   Reply With Quote
Old 03-10-2014, 11:48 PM   #11
I take big bites
iTrader: (1)
 
turbofan's Avatar
 
Join Date: Sep 2010
Location: Hurricane, UT
Posts: 6,924
Total Cats: 526
Default

"I keep breaking bolts. Can you make them stronger"

"Let's first make sure the simple things are fixed..."

"NO. I WANT TO MAKE THE BOLTS STRONGER."

Ok derp.
turbofan is offline   Reply With Quote
Old 03-10-2014, 11:57 PM   #12
Elite Member
 
Join Date: Oct 2013
Location: Cedar City, UT
Posts: 2,769
Total Cats: 948
Default

Something my dad taught me when wrenching on bicycles. When torquing those small bolts/screws/allens, grip the socket wrench by the head, not the tail. That way you have a lot harder time physically being able to over-tighten something

Also tap&die everything if you feel the slightest resistance. I've worn out a couple M6x1.0 taps.

Start threading the bolt by hand, your skin gives you better feedback than a wrench.
Jeffbucc is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Project Gemini - Turbo Civic on the Cheap Full_Tilt_Boogie Build Threads 57 07-19-2017 05:11 PM
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
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 08:55 PM.