chrome moly roll cage - Hot Rod Forum : Hotrodders Bulletin Board -- Hot Rod Forum

Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> General Rodding Tech
User Name
lost password?   |   register now

LinkBack Thread Tools
  #1 (permalink)  
Old 09-01-2007, 01:40 AM
Registered User
Join Date: Oct 2003
Location: san jose ca.
Age: 67
Posts: 18
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
chrome moly roll cage

hello to all..
how can I tell if I have a chrome moly or mild steel roll cage in my car?? can I tell what the thickness of my roll cage is if I have no exposed ends??

Reply With Quote Quick reply to this message
Sponsored Links
  #2 (permalink)  
Old 09-01-2007, 01:53 AM
Metal Twister's Avatar
Change is Opportunity!

Last journal entry: One More Seat
Last photo:
Join Date: Jun 2007
Location: SoCal Diego
Posts: 246
Wiki Edits: 0

Thanks: 1
Thanked 2 Times in 2 Posts
Well uncle dave, DOM Molly has no seam so if there is no seam line you could have a molly cage. But DOM steel is also (drawn over mandrel) and it has no seam either. The good news is both of these products are plenty strong for a cage application unless a racing orginazition requires moly. Moly tends to be a little darker in color but not always. Ive been buying German made moly and it is very light in color. I build Offroad Racing Frames, and for years we had to drill a hole in the frame so the SCORE officials could look in and measure the thickness. Now days he has an ultrasound device that reads the restance of the metal and thus the thickness of the tube.

Last edited by Metal Twister; 09-01-2007 at 07:25 AM.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 09-01-2007, 07:27 AM
Will I ever get it done?

Last journal entry: Hood
Last photo:
Join Date: Oct 2004
Location: Tulsa, OK
Age: 60
Posts: 1,052
Wiki Edits: 0

Thanks: 1
Thanked 3 Times in 3 Posts
I know NHRA requires different minimum wall thicknesses for carbon steel and chrome moly.

If you have to know for sure, check with companies that x-ray pressure vessels. Around here, most of them also perform positive material identification. PMI is a non destructive test which shoots x-rays into the metal and then reads the way the "reflect" to determine what atoms are present and in what percentage. You will have to check with them if they can and are willing to do your cage. They will give you a reader sheet with the results. Does not take the place of a material test report, but if you just need to determine if it is chrome moly or not, this should do it for you.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 09-05-2007, 12:49 PM
bentwings's Avatar
Last photo:
Join Date: May 2002
Location: St.Paul, Minn
Age: 75
Posts: 2,143
Wiki Edits: 0

Thanks: 3
Thanked 86 Times in 75 Posts
If you have a very clean grinding wheel on a bench grinder and some clean samples you can do a spark test. It is still very tough tell even from this. Mild steel has a red spark with few bright stars and molly will be somewhat brighter and more bright stars. It's still hard and even experts can be fooled. I do it side by side then have someone switch samples. I miss about 25% so I'm only a bit above guessing. haha.

On a bare unblasted chassis moly is smooth and a slight OD green gray where mild steel will more black gray. Drill a 3/16 hole with a slightly dull bit and you can tell right away. You might be lucky just to get thru molly where mild steel you can "wear" it thru.
Reply With Quote Quick reply to this message

Recent General Rodding Tech posts with photos

Quick Reply

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Please select your insurance company (Optional)


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools

Posting Rules
You may post new threads
You may 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 On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
roof chop and roll cage sparky82 Body - Exterior 1 09-04-2006 08:48 AM
race car roll cage steammaker7 Garage - Tools 5 03-04-2005 02:32 AM
Welding Chrome Moly johnsongrass1 General Rodding Tech 10 04-07-2004 03:28 PM
Roll Cage - 351W Powered Ford Pinto nightrain_rod Suspension - Brakes - Steering 11 12-07-2003 12:17 PM
Quick 77 Camaro Roll Cage Question izzymiddleton Hotrodders' Lounge 0 01-10-2003 09:35 PM

All times are GMT -6. The time now is 01:04 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999 - 2012. All Rights Reserved.