I have noticed a few threads lately about 40 frame rails breaking above the rear spring hangers. On my '75, there is an inner c-channel that connects to the outer c-channel and the hanger. Do the earlier frames not have this? It just seems hard to believe that this would easily brake if everything was in good shape.
Question on 40 Frames Breaking Above Rear Spring Hangers (1 Viewer)
- Thread starter JJS
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From the pics I've seen what actually happens is that the twisting forces on the bracket, which stands off to the side of the frame, can cause a fatigue crack around the bracket which eventually allows it to tear a chunk out of the frame. On my BJ40 the bracket itself started to crack, so I got a gusset welded in to take the load up to the top of the frame. The pics I saw, the frame didn't actually break, just a piece of the bottom pulled out, still riveted to the bracket. In the ?J42s Toyota installed a piece to transfer some of the twisting force to the top of the frame, this seems to eliminate the problem.
My rear right hanger cracked, so I welded it. It cracked again, so I welded it better. If it cracks 3 times I will gusset it and do it properly. Common problem.. Mine is '78
it looks like poser has the right idea in his fixes by creating a gussett that connects the bracket to both the top and bottom corners of the frame. the stock design allows for torsional force on that single lower corner of the frame by landing the top part of the gussett in the middle of the tall and flexible side of the frame.
i'm not an engineer though.
i'm not an engineer though.
My 74 40 has done this on both sides. The twisting forces on the spring hanger cause cracks in the frame, mine both started on the bottom. I welded up the cracks then added steel to the frame in this area. I have had no more problems with cracks but I do keep a close eye on this area for more cracks, and will add gussets to the hangers this winter just for more strength.
Mark
Mark
the boxing of the frame stops just at the rear spring hangers, it is open from there back - so the weakness of the outboarded spring hanger is compounded
my FSM shows Toyota's instructions on how to weld potential cracks in the frame - not so infrequent, apparently
I would think this really only becomes a problem if there are strong forces on the spring hanger, such as when wheeling terrain that requires a lot of flex
my crack happened on the Charoleau Gap trail by Tucson
my FSM shows Toyota's instructions on how to weld potential cracks in the frame - not so infrequent, apparently
I would think this really only becomes a problem if there are strong forces on the spring hanger, such as when wheeling terrain that requires a lot of flex
my crack happened on the Charoleau Gap trail by Tucson
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For any who are willing to spend the time looking under their rigs, there are warning signs. The cracks are not spontaneous and instantaneous; tey develop over time, and are preceded by opening of the outer channel at the back of the fully boxed section, just forward of the spring hangers. I have seen several cruisers with openings between the inner and outer channels approaching 1/4".
Somewhere in my files I have pics of a FJ40 that sold a few years back for more than 20k with close to half an inch of channel separation before the PO decided to gusset the spring hangers....WITHOUT STRAIGHTENING THE FRAME.
No cracks developed in the frame, but the twist was so bad that the spring eye was rubbing on the underside of the hanger on one side with 3/8" clearance at the other end of the hanger!
Somewhere in my files I have pics of a FJ40 that sold a few years back for more than 20k with close to half an inch of channel separation before the PO decided to gusset the spring hangers....WITHOUT STRAIGHTENING THE FRAME.
No cracks developed in the frame, but the twist was so bad that the spring eye was rubbing on the underside of the hanger on one side with 3/8" clearance at the other end of the hanger!
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I think that's what I was looking for...some warning signs. So it seems as though the outer channel will separate from the inner channel over time. Mine isn't doing that at all yet, so I guess I'm okay for now. I've spent tons of time underneath the truck.
Can sort of see my problem in this pic, I know it was caused by a big hit to the front side of the hanger
Can sort of see my problem in this pic, I know it was caused by a big hit to the front side of the hanger
mark,
is this the kind of bulging you were talking about?
I induced some very similar damage to my 40 but did not get the bulging in the inner channel... did manage to bend the spring pin pretty good though. Fix required drilling out rivets, cutting out the bent part of the frame, welding in new steel, plating on the inside and gussets on the outside. Bolted the hanger back on with grade 8 bolts, haven't been back on the trails yet but will be keeping an eye on it for sure.
Tankota
SILVER Star
I had the cracks and inside/outside rails of the frame pulling apart too. Did a huge plate for about 2 feet along the frame with fisheye ends. No prob there in 10 years since the fix. I also had rivets pulling out that had cracked the inside frame between the two rivets. I made new hangers but was concerned about them snagging on things so I made bolt on 'sliders' out of 3/8" plate and have had the whole truck land on them on a rock and they worked perfect.
ps did this several yrs ago. Was briefly concerned that too much metal had been cut off the outer top side of the spring hangers when I made them. But no cracks or flexing evidence have appeared on the outer flange of the hanger so I haven't bothered to box in the top of the hangers.
. I made new hangers but was concerned about them snagging on things so I made bolt on 'sliders' out of 3/8" plate and have had the whole truck land on them on a rock and they worked perfect.
ps did this several yrs ago. Was briefly concerned that too much metal had been cut off the outer top side of the spring hangers when I made them. But no cracks or flexing evidence have appeared on the outer flange of the hanger so I haven't bothered to box in the top of the hangers.
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Some pix of the frame fix on Claudia's rig in this thread.
https://forum.ih8mud.com/az-copper-...putable-shop-do-frame-repair-east-valley.html
https://forum.ih8mud.com/az-copper-...putable-shop-do-frame-repair-east-valley.html
Josie'sLandCruiser
Stop calling it a "FJ."
Hi All:
Yes, I have had this occur on the driver's (left) side rear fixed-end spring hanger a couple of years ago. My understanding is that the more flex the leaf spring has, the more torque is applied to the mount.
To "fix" it I drilled a hole at the end of the crack to stop it from spreading, and had a buddy weld-on a scab plate to re-enforce the whole area. Seems to be working good, but his thread makes me think I need to inspect the other side!
Regards,
Alan
Yes, I have had this occur on the driver's (left) side rear fixed-end spring hanger a couple of years ago. My understanding is that the more flex the leaf spring has, the more torque is applied to the mount.
To "fix" it I drilled a hole at the end of the crack to stop it from spreading, and had a buddy weld-on a scab plate to re-enforce the whole area. Seems to be working good, but his thread makes me think I need to inspect the other side!
Regards,
Alan
