shaking! what is it?

[jjzepplin]

Not being funny here at all. That is dangerous to you and everyone around you. Who the h--- would do that to a truck and then let you drive it?
What could happen? The worst could happen...
Trailing arm x-member is what it's called I believe.

[jjzepplin]

You can buy them all over this forum. I just happen to have one. Not plugging my stuff to you at all here. It's going to be difficult to replace but thank GOD you showed us! I have never seen such butchery.

[theredmeadow]

so if I swap the cross member out that still means I need the drive shafts?

[brad_man_72]

Yikes. I noticed in an earlier post the driveshaft had been shortened, was it ballanced after it was shortened?
But yeah you have bigger problems than that. That truck sits way to high to run a one piece shaft.
I've made quite a few one piece shafts for swb and lwb 67-72s from 3.5" diameter tubing.

If I was you id not drive the truck until you replace the crossmember, driveshaft, and rear end. The PO caused the damage to the xmember, id bet money the driveshaft destroyed the rear end.
I doubt the PO changed the pinion angle (based on the quality of the other modifications). so you should be fine.

Id check the front suspension, brakes, fuel lines, and steering system before I took that truck over 30mph.

As far as your driveshaft goes there's so many variables that effect the length then the condition issues from using a 45 year old driveshaft that you're better off time and money wise to take measurements from your truck to a driveline shop and have them build you a new 2 piece driveshaft specifically for your truck.

[theredmeadow]

Originally Posted by brad_man_72

Yikes. I noticed in an earlier post the driveshaft had been shortened, was it ballanced after it was shortened?
But yeah you have bigger problems than that. That truck sits way to high to run a one piece shaft.
I've made quite a few one piece shafts for swb and lwb 67-72s from 3.5" diameter tubing.

If I was you id not drive the truck until you replace the crossmember, driveshaft, and rear end. The PO caused the damage to the xmember, id bet money the driveshaft destroyed the rear end.
I doubt the PO changed the pinion angle (based on the quality of the other modifications). so you should be fine.

Id check the front suspension, brakes, fuel lines, and steering system before I took that truck over 30mph.

As far as your driveshaft goes there's so many variables that effect the length then the condition issues from using a 45 year old driveshaft that you're better off time and money wise to take measurements from your truck to a driveline shop and have them build you a new 2 piece driveshaft specifically for your truck.

Everything else seems to be working fine. I've unfortunately been driving it for the past couple months off and on. I've had it sit for like 2 months while ordering other parts but this vibration has been bugging me so today I decided to find the cause and a possible solution.

[Ironangel]

That cross member could be the cause of the grinding noise, possibly rubbing the drive shaft. It appears to have been making contact...In any case, stop driving that truck! Your going to have to replace the cross member because that one is busted and appears to have collapsed or overlapped at the the top. Get the truck in a garage and support it on jack-stands so you can remove the bed and have plenty of access to the cross member, drive shaft, and rear axle. Those cross members are riveted so a grinder and a punch will be needed to remove the butchered cross member and grade 8 bolts used to install the replacement cross member...I'll stop here...Now this is just me ok? "I" would go to the previous owner and get some if not all of my money back! Now I dont the history of your truck or "who" cut that cross member but that truck should have never been sold as a driver with a cut UN-reinforced cross member like that...The truck is easily repairable, but its going to involve lots of time and money...Your looking at replacing a cross member, bushings and bolts for the trailing arms, carrier bearing, two piece drive shaft, complete rear differential assembly w/axles and bearings, (or have the one you have rebuilt) and a set of new U-bolts...Now your right where many of us have been in making decisions in the maintenance and restoration of these old trucks...Do I keep it? Do I have the money and time? Do I have the resources like a garage and the tools?...I feel for ya kid! Somebody's going to chime in with the big idea of reinforcing the existing cross member...That's certainly doable for an experienced welder...Your still going to have to deal with that rear end and that drive shaft getting balanced and that's to say nothing of resetting that pinon angle for a one piece drive shaft which obviously was never done...Bad deal, I'd sure be givin that guy you bought the truck from a "heads up!" Good luck...

[CC69Rat]

I keep thinking SWB.. sorry. ^^ he's right. LWB is to your advantage right now as removing the bed will give you access to get the old cross member out and replaced correctly.

[RenoKeene]

Wow! That is the most dangerous, irresponsible mod I have ever seen on these trucks. I personally would be following the PO to the hospital to get my shoe back.

[CC69Rat]

Here's a picture of what's going on. The trailing arm bushings will probably need to be replaced too while you have it apart.

The cross member (where the trailing arm brackets are riveted on) .. the part that was hacked in half .. will need to be replaced. I just want to help you get it worked out.. for me anyway, understanding the situation is half the battle sometimes. Just thinking out loud.

With the center part of the cross member missing the trailing arms will kinda flop around (not drastically but they will move) and that's probably what you hear with the grinding sound.

There's not much support then for the rear end housing. It too will kinda shift from side to side, front to back even a little. The drive shaft is serving / trying to hold things in line.. and likely causing the harmonic vibration we spoke about earlier. It's 'all over the place' because there is just nothing to keep it from moving. Vibration can cause the universal joints to fail. IF the front universal were to fail, the front of the drive shaft drops down to the pavement and could 'dig' into the asphalt.. (that's why there's a loop in the bottom of the cross member) and send the truck up in the air like a catapult. (extremely rare cases .. but it could cause you to wreck or to hit someone else) IF the drive shaft fails completely - you're stranded. IF you're on the freeway and it fails, .. it could fall out on the road and hit someone else's car.. I think you get the idea.

I would suggest working out a plan to get the bed off. There are several rivets (not something you can just unbolt) this cross member to the frame. It will need to be ground down / Air hammer and then the rivets punched out. It's a PITA.

New one goes in with grade 8 bolts, trailing arms get new bushings and put back together. Honestly I'd convert it back to a 2 piece drive shaft with a carrier bearing. The General made it that way for a reason.

Just my .02 .. I'm sure others will chime in. If I were closer to you I'd help you .. but ..

[theredmeadow]

Originally Posted by CC69Rat

Here's a picture of what's going on. The trailing arm bushings will probably need to be replaced too while you have it apart.

The cross member (where the trailing arm brackets are riveted on) .. the part that was hacked in half .. will need to be replaced. I just want to help you get it worked out.. for me anyway, understanding the situation is half the battle sometimes. Just thinking out loud.

With the center part of the cross member missing the trailing arms will kinda flop around (not drastically but they will move) and that's probably what you hear with the grinding sound.

There's not much support then for the rear end housing. It too will kinda shift from side to side, front to back even a little. The drive shaft is serving / trying to hold things in line.. and likely causing the harmonic vibration we spoke about earlier. It's 'all over the place' because there is just nothing to keep it from moving. Vibration can cause the universal joints to fail. IF the front universal were to fail, the front of the drive shaft drops down to the pavement and could 'dig' into the asphalt.. (that's why there's a loop in the bottom of the cross member) and send the truck up in the air like a catapult. (extremely rare cases .. but it could cause you to wreck or to hit someone else) IF the drive shaft fails completely - you're stranded. IF you're on the freeway and it fails, .. it could fall out on the road and hit someone else's car.. I think you get the idea.

I would suggest working out a plan to get the bed off. There are several rivets (not something you can just unbolt) this cross member to the frame. It will need to be ground down / Air hammer and then the rivets punched out. It's a PITA.

New one goes in with grade 8 bolts, trailing arms get new bushings and put back together. Honestly I'd convert it back to a 2 piece drive shaft with a carrier bearing. The General made it that way for a reason.

Just my .02 .. I'm sure others will chime in. If I were closer to you I'd help you .. but ..

Thank you for this information. I appreciate your response and I now know how serious it can be for me to be driving around like it is. I hadn't realized it till you put it in those terms.
How hard will it be to install the new crossmember without removing the bed? By looking at it and with my non existent experience it looks like we pop the rivets off and pull the crossmember off and put the new one in place?

[faribran]

What RENO said... LOL

[mrolds88]

I don't believe you could replace the crossmember without pulling the bed. Pretty sure there are rivets on top. Also when you replace it, use good grade 8 bolts. Most rivets are nominally 3/8". but the usually check out slightly bigger. I usually drill out to 7/16", then with the new bolts there is a lot less chance of movement. That job on that crossmember is about as dangerous thing as I have ever seen on a vehicle. As far as your original problem, I would go for a rebuild or replace. I had a Suburban that did the same thing a few years ago. As heavy as that thing was, it would shake you teeth loose above about 45 MPH. Pinion loose just like yours. Tightened the pinion nut and was fine, but replaced the rear anyway. PO had replaced the pinion seal. I don't know if they didn't torque the nut or nut was worn.

[magwakeenercew2jh]

Originally Posted by theredmeadow

Thank you for this information. I appreciate your response and I now know how serious it can be for me to be driving around like it is. I hadn't realized it till you put it in those terms.
How hard will it be to install the new crossmember without removing the bed? By looking at it and with my non existent experience it looks like we pop the rivets off and pull the crossmember off and put the new one in place?

I don't usually give advice. But, I can give you the "benefit of my experience".

First, I lied. I have to break the Rule #1, above:

I don't care how little or much experience, money, or energy you have. I don't care whether you have a good place to work on your truck.
Or whether or not you have friends to help with the heavy lifting. Or any of that s&^t.

If you have anyone that loves you, you love yourself, or even if you just have a dog that you feed, stay out of that truck..... until it's fixed.

Part Two:

Although a confirmed gearhead for fifty years, I've only built two 67-72 trucks. I'd take the f'ing bed off of that truck and start pulling stuff in four minutes.
Yeah, the rivets on that cross member are a PIA. So what? It's a hobby, right. Jack stands and blocks are pretty cheap. Especially when measured against
gauze, plaster casts, peg legs, and eye-patches.

Upsides to doing the fix are plenty. The parts are around, and not ugly on the pocket book. It's plug-and-play on most of the parts. Big parts. And heavy
plug-and-play. But very do-able. Caution! You need to have some practiced and learned eyes focused on the internals of the rear end, and their pro measurements....
And on any possible tweeked parts that you may try to re-use.

I got a book years ago. Best $40 for a Chevy I've ever spent.

And, when you're done, you'll likely not ever again have to ask, "....how hard is it to.......?" Now, that's never a bad question to ask. Just, when you're done,
it's not one you'll need to ask about any tranny-back engineering.

If I were you, my problem in all of this this would be raising the bail money after I plummeted the P.O. Especially since it would cost me because when the
Boys in Blue showed up, I'd be whacking him around with an adjustable panhard bar while he was yelling, "I didn't know"..."I swear". "I didn't know!"

Hell, I might even take a couple of whacks at myself for not seeing this dangerous mess earlier...But that's just me.

"Thunk-thunk-thunk".

Enter-stage left; lots'o black and whites...Siren's harmonizing.

[theredmeadow]

ok I guess I'm out of a truck until I can get it fixed. The problem with getting a hold of the PO is that he's long gone. I acquired this truck in like September. Also, I traded my 98 sportster for it so there wasn't any money exchanged. I've had another mechanic work on this truck prior but for other reasons and funny thing is that no one who's looked at this truck every noticed it.

Originally Posted by magwakeenercew2jh

I don't usually give advice. But, I can give you the "benefit of my experience".

First, I lied. I have to break the Rule #1, above:

I don't care how little or much experience, money, or energy you have. I don't care whether you have a good place to work on your truck.
Or whether or not you have friends to help with the heavy lifting. Or any of that s&^t.

If you have anyone that loves you, you love yourself, or even if you just have a dog that you feed, stay out of that truck..... until it's fixed.

Part Two:

Although a confirmed gearhead for fifty years, I've only built two 67-72 trucks. I'd take the f'ing bed off of that truck and start pulling stuff in four minutes.
Yeah, the rivets on that cross member are a PIA. So what? It's a hobby, right. Jack stands and blocks are pretty cheap. Especially when measured against
gauze, plaster casts, peg legs, and eye-patches.

Upsides to doing the fix are plenty. The parts are around, and not ugly on the pocket book. It's plug-and-play on most of the parts. Big parts. And heavy
plug-and-play. But very do-able. Caution! You need to have some practiced and learned eyes focused on the internals of the rear end, and their pro measurements....
And on any possible tweeked parts that you may try to re-use.

I got a book years ago. Best $40 for a Chevy I've ever spent.

And, when you're done, you'll likely not ever again have to ask, "....how hard is it to.......?" Now, that's never a bad question to ask. Just, when you're done,
it's not one you'll need to ask about any tranny-back engineering.

If I were you, my problem in all of this this would be raising the bail money after I plummeted the P.O. Especially since it would cost me because when the
Boys in Blue showed up, I'd be whacking him around with an adjustable panhard bar while he was yelling, "I didn't know"..."I swear". "I didn't know!"

Hell, I might even take a couple of whacks at myself for not seeing this dangerous mess earlier...But that's just me.

"Thunk-thunk-thunk".

Enter-stage left; lots'o black and whites...Siren's harmonizing.

[magwakeenercew2jh]

Originally Posted by theredmeadow

ok I guess I'm out of a truck until I can get it fixed. The problem with getting a hold of the PO is that he's long gone. I acquired this truck in like September. Also, I traded my 98 sportster for it so there wasn't any money exchanged. I've had another mechanic work on this truck prior but for other reasons and funny thing is that no one who's looked at this truck every noticed it.

Yeah. Keeping things simple, I'd forget the P.O.

I just hope your Sporty had a hole in the rear piston.
And fleas in the seat.

[CC69Rat]

Do yourself a favor and pull the bed off. The rivets are a huge job and you'll need a BFH to get them out. The problem is having the room to swing said BFH with the bed on.

I'm not going to keep commenting on how this happened man.. for all we know the guy you got it from truly didn't know it was cut ?.. my advice at this point is just take it as a life lesson and learn from it, fix it, and enjoy the truck.

Maybe there's some people on the board that could help you do it. .. who knows. .. but I would plan on a couple weekends. Not something you want to tackle by yourself.

[boynton]

man if I were closer I would help. Rivits suck but since ive cut a few they are not that bad. and yes you are out of a truck until you can get it fixed. $40 for the x-member isnt bad. start by replacing that and then move onto the driveshaft issue/rear-end problem. Not sure what a rear-end rebuild will cost but mine was around $450-$500. That was all new parts ring and all. You might be able to get by a little cheaper, but don't try to do it yourself. As mentioned before a rear-end needs to be set up with specialty tools and by someone who knows what they are doing or in 5-10,000 you will be doing it again. you can skimp on certain parts-radio interior, dont skimp on drive-line stuff-brakes, suspension, or tires. these are the things that keep you safe and your truck in one piece. Best of luck.

Don't give up on it, but spend your money wisely.

[theredmeadow]

I wish you all were nearby because I could use the help! I appreciate your responses. I think I will keep it simple for now which means, remove bed, replace crossmember, replace trailing arm bushings, get new 2 piece drive shafts and see how that impacts everything. Eventually I'm going to rebuild the differential but that won't be till later.

[brad_man_72]

Search craigslist, try to find some local truck guys. I gave away a good 12 bolt rear a while ago to a couple of board members/friends. People swap this stuff out all of the time, truck parts aren't worth as much as car parts so there's some deals to be found.

[jjzepplin]

OK - cross-member went out yesterday. Cost a bit more to ship than I thought but what the heck. It's going to a GOOD cause! Your on your way to having a nice-safe- riding truck. Rivets are a pain to remove. I cut a "x" through the middle of the head with a die grinder and then use an air hammer to knock off the little pieces left over. Then a flat tipped chisel on the hammer(not pointed!) to punch the rest out. If I was closer I would do it for you but alas I am not. Will send tracking info on a private message to you.
Look up the torque specs on the yoke to your rear end and try to torque it first. That may help.

[theredmeadow]

Thanks JZep. I went to UPull today and found the front 1/2 of the 2 piece drive shaft! I need to order a center support bearing for it. Anyone have drive shaft Ujoint yoke?? And anyone have the rear drive shaft to sell??? those 2 pieces are the last of what I need to get it back to working order!!

[jjzepplin]

Hope the x-member works out for you.

[theredmeadow]

ok I fixed that issue, now I shouldn't have to worry about asking. JZep do you have a rear shaft to sell?

[jjzepplin]

Good job there! I have a shaft from a 4wd with a slip joint in it for articulating the axle but I'm not sure if that is the one you need. I need one without the slip joint and I was just going to have this one taken off and lengthen it.

[theredmeadow]

I guess I need the slip yoke for the drive shaft. I have no clue. It would be whatever is standard for a 70 long bed 2 piece drive shaft.