So how important are these?

[motormayhem]

Well after driving today I noticed around lunch that the truck would chirp when it was accelerating. I discovered that the problem was the center cross member bolts coming loose and one missing allowing the transmission to move around a lot while being torqued. Tightened the remaining bolts and meandered home. So my question is the bolts go through the crossmember, then the frame, then this 1" tall spacer and then there is the nut. well one of those spacers is now somewhere between speedway and river and I think it is going to be a annoyance to find a new one so is there any use for it or can I just get a smaller bolt and some washers and call it good?

Here is a pic of the spacers with the crossmember

 

[FireFighterHill]

Just make one out of piece of steel tubing the approximate diameter. Or washers should do the trick also

 

[motormayhem]

So if I switch them to shorter bolts with washers and just remove all the spacers there will be no difference? What is there purpose then?

 

[FireFighterHill]

I wouldnt remove the spacers. Im sure they are there for a reason. I dont own a CUCV, im just saying what I myself would do in your situation. Im sure someone will chime in by tomorrow.

 

[motormayhem]

Well the problem with making them out of tubing is they are real thick.

 

[FireFighterHill]

Look up a machine shop near by take one with you to there shop and ask them to replicate it. Should be simple to do on a lathe.

 

[68impalass]

if you look in the parts manual it shows the spacers between the frame and the cross member. I think they are pretty important.

 

[LanceRobson]

If I understand the engineering intent of the heavy wall spacer correctly; it allows for a little flex without accumulated stress cracking the frame (Just like the ones for the bolts on the steering gear box protect the frame).

I'd go to a Chevy or GM truck dealer and look over the parts guy's shoulder while he finds the right exploded diagram and order one. Also, as a stab in the dark, try the local transmission shops.

Lance

EDIT: Jeez! I'm not thinking! I've got a parts truck in the shop with the transmission and transfer out of it. I'll bet the spacers are in the truck. Shoot me your address and I'll send you one.

 

[ralbelt]

68Impallass is right the Tm9-2320-289-34p figure 140 shows them between the crossmember and frame. Although when I removed my transmission/TC they were above the frame looks like I have to crawl under and move them unless the TM is wrong.

 

[3dubs]

Removing the spacer and using a shorter bolt will cause the frame or the bolt to crack and fail. The trans moves and there needs to be flex to prevent someting from braking. It is a spacer so the part should be easy to get. If you really want to make one get steel pipe with the same internal diameter and similar thickness. Use a band saw or hack saw and cut it slightly long. Then using water to keep it cool grind it down to the correct length. Or just put a floor jack under the crossmember to hold the trans. Remove the bolt with the spacer leave the other bolt there in case the jack drops. Use another vehicle to go to the parts store and say I need one of these. I am sure you can put them back. Your choice but I go for simple.

 

[motormayhem]

68Impallass is right the Tm9-2320-289-34p figure 140 shows them between the crossmember and frame. Although when I removed my transmission/TC they were above the frame looks like I have to crawl under and move them unless the TM is wrong.

Mine are on top too.

 

[3dubs]

Yeah mine are on top too. So it holds the crossmamber firmly to the frame. But when cross preasure is applied like when the trans twists because of torque, then the bolts can move slighty above the frame and keep the crossmember tight against the frame.

 

[ralbelt]

So I guess the majority rules and above the frame is right and the TM is wrong. Not the first time printed service notes were wrong.

 

[motormayhem]

Ok here is how their importance was explained to me. In this system the bolts act as springs. When under tension like they are they are able to stretch and shrink just a little as the transmission torques them and they absorb just enough energy to prevent cracks in the frame and crossmember. So by using the longer bolts there is more bolt to strech and absorbe energy. If you eliminate the spacers and use shorter bolts there is less bolt to stretch and will eventually result in a failure. However I talked to two mechanics who said they work just as well withou them so I don't think they are crucial, but I made a new one with a hole saw and some plate I had laying around.

 

[acmunro]

Above the frame is correct.

 

[1stDeuce]

Yeah, your last post is close to correct motormayhem... Really the spacer isn't there so the crossmember can move, but rather so that if it does move a little, the bolts don't loosen up. If you use a short bolt, even torqued, it doesn't take much relative movement to lessend the clamp load and loosen the bolt. Using a long spacer allows a longer bolt, and more "Stretch" on the torqued bolt, and hence holds clamp load better without loosening, even given a little bit of relative movement. If you look, you'll see the steering gear has the same spacers on it. That's for the same reason, as if you toss short bolts in there, they quickly loosen and fall out. It's all about the amount of stretch that the torqued fastener needs to retain it's torque over time.

Anytime you bolt two thin pieces of metal together, you'll notice that they quickly loosen if subjected to a lot of stress. Adding more tensioned bolt length will usually prevent that from happening.

And yes, the spacers go on top, not between, though lift manufacturers often tell you to put the inbetween after lifting the truck. Not a real good idea, as the crosmember is kinda wobbly on the spacers, and cracks develop pretty quickly if used hard... Better off with some thick wall 1x1 square tube in place of the spacers if you must drop the crosmember.

Fun stuff!!
C
.

 

[3dubs]

I just know without the frames and bolts brake when you are having fun. Normal driving on the street is no big deal. When I asked about spacers on a truck the redneck answer I got was, "I ain't tak'n em off my truck, if you take em off I will be laugh'n at you real soon."