I started to disasemble my 79 CJ7 to replace the dead 304 with a 351W/T18 combination and noticed that the frame appears to be tweaked. I'm trying to figure out if it really is or if it is supposed to be that way. If I stand at a distance it appears that right in front of the firewall the frame bends to the passenger side. The crankshaft from the motor does not line up with the center mount for the radiator support, The outside of the rear passenger side tire stops almost deadcenter of the front passenger side tire. The outside of the rear drivers side tire is even with the outside of the front driverside tire. to me that says Bent frame, However when I get close there are no signs of the frame bending. None of the welds are broken, there aren't any stress cracks in the undercoating, it uses the double C channel frame construction and where the 2 pieces overlap the weld lines are still in tact if it was truly bent I figure the weld or something should have given to allow the 2 pieces to bend. Both of the frame rails at a distance appear run parallel to each other over the entire course so the bend would have to be at the same spot on both rails. am I being fooled by an optical illusion?
Bent Frame??
- Thread starter Keith__C
- Start date
Bounty__Hunter
Super Moderator
It's not uncommon for engines to be installed slightly off-center, not sure what the specs on a CJ7 are though.
You can't judge the straightness of the frame based on where the tires are, there are no track bars on a CJ to hold the axles in place side to side. It's easy for your axles to shift sideways, especially if the shackle and spring bushings are worn.
You can't judge the straightness of the frame based on where the tires are, there are no track bars on a CJ to hold the axles in place side to side. It's easy for your axles to shift sideways, especially if the shackle and spring bushings are worn.
RangerRick
New member
CJ's have the engine slightly off to one side. There are lots of reasons why Jeep did this. On a lifted Jeep it isn't a problem but stock there was just enough room to fit the small diameter front drive shaft between the pan rail and the TC. If the engine was centered the front driveshaft would hit the oil pan. The non centered engine is not an illusion.
Rick
Rick
Utah_jeepster
Super Moderator
Do all jeeps have an offset motor? anyone know?
I never looked myself.
I never looked myself.
SteelHeadz
Super Moderator
Very few vehicles were built with a "centered engine". Mostly small sized frames with the 4 cylinders thats never going to see a 6 or 8 cylinder. The reason for an offset is due to the torque rotation of the engine and the powertrain to minimize the frame from twisting due to the horsepower. Most of the offsets are towards the passenger side for 2wd and 4wd depending on how the frame was designed along with the crossmember locations. Weight distribution also plays a big role on this to counter some of the lift from one side of the engine. As for the Jeeps having an offset engine, i've never done any comparisons on them. It's got me curious. Its time to dig.
Saddle Tramp
New member
Keith-
Bent frames of course are common place in 30 year old Jeeps that have been used off road and who knows what happened to the Jeep under the control of previous owners. One way to quickly check the frame (although not fool proof) if there is no signs of tweaking on the frame its self is to sight down the side of the body from front to back and back to front. Typically if the fame bends the body parts go with it so if you have a problem things will not look straight, a bend or wow may be visible. If you have the front clip off this may not work. However the most common frame bending I have seen over the years is bending upwards between the front wheels and the tub. This bending occurs when bumps are repeatedly hit while traveling too fast causing the frame to move upwards. It is logical that the frame could move both up and to the side at the same time, which may the issue here. On 76 & up CJs eyeball the hood to see if it appears to lifted up towards the front. Often the gap between the bottom of the hood and the top of the fenders will appear to be close enough to not raise suspicion but if the gap is off (wider at the firewall than the front) it begs the question. On 72 to 75s look for a bubble or puckering in the tub body just below or in front of the door opening. I have seen a lot of tubs with repairs in this spot.
Of course the only way to really know is to put the Jeep on a frame machine and go from there. The good news is it has been my experience when the frame is straightened the body parts move with it. As such, I would not straighten a frame without all of the body parts in place as once the frame is straighten any body parts left off may no longer line up.
Bent frames of course are common place in 30 year old Jeeps that have been used off road and who knows what happened to the Jeep under the control of previous owners. One way to quickly check the frame (although not fool proof) if there is no signs of tweaking on the frame its self is to sight down the side of the body from front to back and back to front. Typically if the fame bends the body parts go with it so if you have a problem things will not look straight, a bend or wow may be visible. If you have the front clip off this may not work. However the most common frame bending I have seen over the years is bending upwards between the front wheels and the tub. This bending occurs when bumps are repeatedly hit while traveling too fast causing the frame to move upwards. It is logical that the frame could move both up and to the side at the same time, which may the issue here. On 76 & up CJs eyeball the hood to see if it appears to lifted up towards the front. Often the gap between the bottom of the hood and the top of the fenders will appear to be close enough to not raise suspicion but if the gap is off (wider at the firewall than the front) it begs the question. On 72 to 75s look for a bubble or puckering in the tub body just below or in front of the door opening. I have seen a lot of tubs with repairs in this spot.
Of course the only way to really know is to put the Jeep on a frame machine and go from there. The good news is it has been my experience when the frame is straightened the body parts move with it. As such, I would not straighten a frame without all of the body parts in place as once the frame is straighten any body parts left off may no longer line up.
If you've got the drivetrain out of the frame, you can measure diagonally across the frame in a few places. Pick the same points along both frame rails and then measure diagonally to a point on the other frame rail. Repeat on the other side. If the distances are different, the frame rails are not parallel.
As for looking for signs of bending (cracks, broken welds...etc). Those are certainly signs of movement. However, there is enough "elasticity" in steel to bend without breaking anything. You can have a bent frame and not see any broken welds, cracks, chipped paint..etc.
As for looking for signs of bending (cracks, broken welds...etc). Those are certainly signs of movement. However, there is enough "elasticity" in steel to bend without breaking anything. You can have a bent frame and not see any broken welds, cracks, chipped paint..etc.
Keith,
I have the same kind of thing on my YJ '91. The previous owner must have ditched because we bought it at auction and it was pulled to fix. We had a blacksmith, really, look it over and one body mount bolt is twisted a bit but no pull when driving stopping or tire wear. So mine may be slightly bent but it does not affect performance.
I am about to change my body mounts. Does anyone have suggestions for the one that is pulled at a angle?
Vasily
I have the same kind of thing on my YJ '91. The previous owner must have ditched because we bought it at auction and it was pulled to fix. We had a blacksmith, really, look it over and one body mount bolt is twisted a bit but no pull when driving stopping or tire wear. So mine may be slightly bent but it does not affect performance.
I am about to change my body mounts. Does anyone have suggestions for the one that is pulled at a angle?
Vasily
Saddle Tramp
New member
If you take your jeep to a frame shop and have the frame straightened generally the tub follows. That may help.
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