Go Back   The Ford Barn > General Discussion > Model A (1928-31)

Sponsored Links (Register now to hide all advertisements)

Reply
 
Thread Tools Display Modes
Old 04-12-2017, 09:59 PM   #1
louieglen
Senior Member
 
Join Date: May 2010
Posts: 218
Default Frame straightening

I know there several threads on straightening, but I haven't saw any about doing it with the body, and engine in place. A fellow told me if you didn't loosen the motor mounts there is a high possibility of cracking the bell housing Has anybody had this to happen? He said to take out one bolt and loosen the other on both sides.
louieglen is offline   Reply With Quote
Old 04-13-2017, 01:00 AM   #2
Dave Mellor NJ
Senior Member
 
Join Date: May 2010
Posts: 761
Default Re: Frame straightening

I was told that can happen when you jack the front of the engine up to change the timing gear. I never heard about that danger when straightening the frame.
Dave Mellor NJ is offline   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 04-13-2017, 01:35 AM   #3
jw hash
Senior Member
 
jw hash's Avatar
 
Join Date: May 2010
Location: Auburn Washington
Posts: 2,550
Default Re: Frame straightening

if you know what you are doing. and have the right equipment you can straighten a frame with the body and motor in place. I had a badly bent Model A frame in here, the car had hit a ditch pretty hard. so the right rail was up 1" from the rear motor mount forward. the body itself was not damaged so I removed all the nuts on the body mount bolts and straighten the frame than rebolted the body down.
jw hash is offline   Reply With Quote
Old 04-13-2017, 06:48 PM   #4
grj
Senior Member
 
Join Date: May 2010
Posts: 1,414
Default Re: Frame straightening

Great article in the latest MAN. Did that with my Henry car as it left the judging field. G
grj is offline   Reply With Quote
Old 04-13-2017, 07:31 PM   #5
MikeK
Senior Member
 
MikeK's Avatar
 
Join Date: May 2010
Location: Windy City
Posts: 2,919
Default Re: Frame straightening

Sponsored Links (Register now to hide all advertisements)
The frames almost all sag in the area of the motor mounts and the first body mount, just behind the motor mounts. This becomes the fulcrum, or pivot point for the correction of the sag. If you look at an old play lot teeter-taught-er you will see the closer to the pivot point the lesser the movement.

Since the motor mounts are with rubber pad and plates, and not bolted solid they are relatively compliant to frame flex and excursions at that pivot or fulcrum point. If that point is made the fulcrum with blocking during straightening. then the very slight movement, even as you over-bend the ends to compensate for spring back, will be of little consequence. I'd really be more concerned about loosening the rearward body mounts, which are farthest from the bend fulcrum.

I've straightened two frames with the motor mounts bolted in place and it didn't cause any damage. I would think driving over a rough set of RR tracks or a big pothole, and the resultant front wishbone slamming would put far more load on the cast iron flywheel cover than the non-impact forces of frame straightening.

That all said, the best method of frame straightening involves SHRINKING the stretched under cord of the "C" section in addition to stretching the compressed top cord.

The advantage to leaving the motor mounts untouched while straightening is lateral deflection and twisting will be contained while you attempt to apply vertical excursions on a "[" section.

After straightening would be a good time to replace the motor mount rubbers, you need them anyway if the frame was bent, as the bolts likely cut into them long ago.

Now, if the frame is bent laterally (inward from the side) somewhere else due to previous collision history then all bets are off, best to unbolt both the engine and body mounts.

Your experience may vary! Expect to be playing with body block shimming to re-align the body panel seams and door closure after the frame is true.
MikeK is offline   Reply With Quote
Reply

Thread Tools
Display Modes

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

Forum Jump

Sponsored Links (Register now to hide all advertisements)


All times are GMT -5. The time now is 02:23 PM.