Notices
928 Forum
Sponsored by:
Sponsored by: 928 Specialists

Chassis Rail Straightening

 
Old 11-27-2016, 01:42 AM
  #1  
G.P.
Addict
Rennlist Member
Thread Starter
 
G.P.'s Avatar
 
Join Date: Dec 2013
Posts: 161
Likes: 0
Received 0 Likes on 0 Posts
Default Chassis Rail Straightening

Have you been working under your 928 and keep noticing the dents in the chassis rails from inappropriate use of a jack?
After being inspired while reading through this thread https://rennlist.com/forums/928-foru...rrived-65.html, I decided to do something about mine.

You can access the inside of the rails from inside the car via holes in the floor. Lift up the carpets and press on the material that the factory has stuck on the floor to locate the holes, then trim the material and peel it off.



I used a bench vice with a couple of pieces of angle iron to press in the sides of the rails before trying to flatten the base. My bench vice is quite heavy, so I used the floor jack to hold the vice up to the rail then tightened it to press the sides in.





After pressing the sides back in I used a hammer and a punch along with a 20mm wide x 120mm long and 5mm thick piece of steel (this will fit through the holes in the floor) to bash the bottom of the rail back down as best I could. You won't be able to do a perfect job due to the restrictions of access through the holes, but I think the steel plate helped with spreading the force from the hammer along the rail away from the hole. It also kept the bottom of the rail flat, whereas the punch would have left round marks in the rail. I also used a 100mm length of 5mm steel rod to try to push out any kinks in the edges of the rails.

Here is a before photo


And some after photo's.










After completing the work I sprayed the inside of the rail with cavity rust inhibitor, and covered the holes with adhesive tape and sound insulation. I need to repair the stuff the factory sprayed on the underside of the car to prevent damage from stones.
A magnet on a telescopic rod (like a portable radio aerial, see photo below) comes in handy when one of the pieces of steel slides down the chassis rail and you need to retrieve it.

Tools Used.


If you look at post number 970 from the thread I mentioned in the start of this post, I would have preferred to use a tool as big as William's. That's a much more adequate weapon.

As I mentioned before, it's not perfect but it is an improvement.
Maybe someone has some other tips.
G.P. is offline  
Old 11-27-2016, 03:59 AM
  #2  
skpyle
Addict
Rennlist Member
 
skpyle's Avatar
 
Join Date: Jul 2014
Location: Blacksburg, SC
Posts: 2,206
Likes: 0
Received 12 Likes on 9 Posts
Default

That's pretty awesome, G.P.!
Thanks for sharing that idea.


Seth K. Pyle
skpyle is offline  
Old 11-27-2016, 06:33 AM
  #3  
Ad0911
User
 
Ad0911's Avatar
 
Join Date: Jan 2003
Location: Netherlands
Posts: 1,668
Likes: 0
Received 0 Likes on 0 Posts
Default

I never thought these chassis rails were not fully boxed. Now it seems logical because the floor must have been stamped out of one piece. Fully boxed would have been a lot stronger in my opinion. But good work because what you did is a true eye opener
Ad0911 is offline  
Old 11-27-2016, 09:31 AM
  #4  
linderpat
Addict
Rennlist Member
 
linderpat's Avatar
 
Join Date: Nov 2006
Location: Pittsburgh, PA
Posts: 10,428
Received 29 Likes on 21 Posts
Default

Yes, those rails were not intended to support the car. Many erroneously believe that they are part of the "frame" (our cars don't have a frame), and use them as the jack supports.
linderpat is offline  
Old 11-27-2016, 12:57 PM
  #5  
Jerry Feather
Addict
Rennlist Member
 
Jerry Feather's Avatar
 
Join Date: May 2008
Location: 2706 Skyline Drive, Grand Junction CO 81506
Posts: 4,542
Likes: 0
Received 0 Likes on 0 Posts
Default

I like the idea of the vice to squeeze the sides of the stiffeners while the bottoms are driven down to about where they should be. I made a tool some time ago to do the hammering downward. It is made of about 3/4 inch round bar bent into a kind of seven-shape and the bottom of it, the top of the seven, is milled so that it has a sharp enough edge to fit the inside of the hat sections. The top of the seven shape is long enough to reach to about half way between the holes in the floor. It works pretty well to beat the bottom of the sections down, but the vice looks like a neat way to pull the sides in.

If I could find the tool I made I would post a picture of it, but I don't remember where it is right now.

Last edited by Hacker-Pschorr; 11-28-2016 at 10:11 AM. Reason: Removing Frame Argument Chatter
Jerry Feather is offline  
Old 11-27-2016, 03:15 PM
  #6  
928sg
Resident 928 Modiholic
Rennlist Member
 
928sg's Avatar
 
Join Date: Mar 2013
Location: Texas
Posts: 2,109
Received 9 Likes on 9 Posts
Default

I did this several years ago on my 928. I cut an H in the floor from above, and drilled a small hole for a punch where there were dents. I then used a string to pull the 1/4th inch thick forward and backward. I then filled the H with lab metal and then installed full pan sound deadening.
928sg is offline  
Old 11-27-2016, 03:26 PM
  #7  
Red Flash
User
 
Red Flash's Avatar
 
Join Date: Jan 2012
Location: The Heartland
Posts: 696
Likes: 0
Received 0 Likes on 0 Posts
Default

Awesome. Thanks for posting G.P.!

Originally Posted by 928sg View Post
I did this several years ago on my 928. I cut an H in the floor from above, and drilled a small hole for a punch where there were dents. I then used a string to pull the 1/4th inch thick forward and backward. I then filled the H with lab metal and then installed full pan sound deadening.
Did you happen to take any pictures of this? I have a dent near my jack pad (https://rennlist.com/forums/928-foru...ad-repair.html) that I would like to fix so that I can jack my car up easily again...
Red Flash is offline  
Old 11-28-2016, 08:23 AM
  #8  
drooman
Addict
Rennlist Member
 
drooman's Avatar
 
Join Date: Jun 2011
Location: CT and FL
Posts: 1,191
Received 28 Likes on 17 Posts
Default

This kind of box section damage is quite common, and I must admit I've done it myself before I knew better! I've started cutting un-bent box sections out of parts cars for future restorations..I'm starting to view these like nice dashboards and un-cut console trims.
drooman is offline  
Old 11-28-2016, 09:45 AM
  #9  
Kiln_Red
Addict
Rennlist Member
 
Kiln_Red's Avatar
 
Join Date: Jul 2010
Location: Bowling Green, KY
Posts: 754
Likes: 0
Received 3 Likes on 3 Posts
Default

Whether body-on-frame construction or unibody, I don't care. Use of the word "frame" is semantical. Even on a unibody, so many manufacturers ID parts as being a frame rail, frame horn, inner and outer rails, etc. The word "frame" gets used for both body-on and unibody. Shops charge for "frame" labor, at a different rate, for structural work whether car or truck, unibody or full frame. It's a word.

That is a nice professional looking repair.
Kiln_Red is offline  
Old 11-28-2016, 10:10 AM
  #10  
Hacker-Pschorr
Super Moderator - Cracklin' Rosie
Lifetime Rennlist
Member
 
Hacker-Pschorr's Avatar
 
Join Date: Aug 2001
Location: Up Nort
Posts: 10,063,041
Received 40 Likes on 27 Posts
Default

Thread clean-up time.

If you guys want to argue about what a frame is or isn't, start a new thread and have at it. Leave this one to discussing the repair of whatever anyone wants to call these parts.
Hacker-Pschorr is offline  
Old 11-28-2016, 05:10 PM
  #11  
GT6ixer
Addict
Rennlist Member
 
GT6ixer's Avatar
 
Join Date: Mar 2016
Location: Seattle. WA
Posts: 3,020
Received 10 Likes on 9 Posts
Default

I think this is a very practical method for returning this chassis section to something close to its original form. But I gotta ask, what is the problem that this solution is addressing other than aesthetics?
GT6ixer is offline  
Old 11-28-2016, 06:08 PM
  #12  
James Bailey
Addict
Lifetime Rennlist
Member
 
James Bailey's Avatar
 
Join Date: Feb 2009
Posts: 18,058
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by GT6ixer View Post
I think this is a very practical method for returning this chassis section to something close to its original form. But I gotta ask, what is the problem that this solution is addressing other than aesthetics?
Same could be said for a large dent in the door
James Bailey is offline  
Old 11-28-2016, 10:17 PM
  #13  
Kiln_Red
Addict
Rennlist Member
 
Kiln_Red's Avatar
 
Join Date: Jul 2010
Location: Bowling Green, KY
Posts: 754
Likes: 0
Received 3 Likes on 3 Posts
Default

Originally Posted by GT6ixer View Post
I think this is a very practical method for returning this chassis section to something close to its original form. But I gotta ask, what is the problem that this solution is addressing other than aesthetics?
It is a painful site when you have it on the lift. I may be ****, but I couldn't live with it either.
Kiln_Red is offline  
Old 11-29-2016, 01:17 AM
  #14  
Hacker-Pschorr
Super Moderator - Cracklin' Rosie
Lifetime Rennlist
Member
 
Hacker-Pschorr's Avatar
 
Join Date: Aug 2001
Location: Up Nort
Posts: 10,063,041
Received 40 Likes on 27 Posts
Default

Originally Posted by Kiln_Red View Post
It is a painful site when you have it on the lift. I may be ****, but I couldn't live with it either.
It's one of the first things I check when looking over a 928.
Hacker-Pschorr is offline  
Old 11-29-2016, 11:14 AM
  #15  
9two8
User
 
9two8's Avatar
 
Join Date: May 2007
Location: Newcastle upon Tyne. England
Posts: 1,272
Likes: 0
Received 0 Likes on 0 Posts
Default

Made this sticker a while back , a bit crude, but they get the point when they shove the jack under there !
Attached Images  
9two8 is offline  

Thread Tools
Search this Thread
Quick Reply: Chassis Rail Straightening


Contact Us - About Us - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: