Transfer case hitting the floor...help

[Leper]

When taking off from a stop in 2WD my 241 moves up and over to the right and hits the bottom of the floor. I am to the point that i'm wondering if the 3.08 and the 35"s is whats causing it. I have the ORD shackle flip and zero rate in the rear. This happened with no shim, a 3* shim and a 6* shim. I had the axle lengthened because the slip yoke was sticking very far out of the tcase, this didn't help either. Yes, I have replaced the tcase mount and the engine mounts and the ujoints. None of it helped at all. I am going to put my old 31" tires on this weekend and see if it helps. In 4WD it doesn't do it, unless I am hard on the skinney pedal, thats why I am thinking the gearing is too tall
BTW I am not talking about stomping it off the line, anything more than just a hair of throttle, and you hear a dunkdunkdunkdunkdunk. 350/700/241
Anyone have this happen before???

 

[3 on the tree]

Would bad body mounts cause the floor to sag down too close to the TC??? My case moves around a bunch, even in 2wd, but it never hits anything.

 

[gzzgfw]

Check your motor mounts, I had an 78 with worn out motor mounts and the engine was lifting like 3-4 inches. Have someone powerbrake it while looking at the engine, Good luck.

 

[Leper]

I didn't look at the body mounts, but the vibration can be felt without the contact. Also the vibration is bad enough that my shifter and steering wheel moves also. I think that is too much movement. If you are beside the truck and are looking at the tcase forward, nothing moves much. It is just right at the rear of the tcase that the movement is the greatest. I thought about putting a strap of somekind around the rear mount to make it stronger, but that only fixes the result, not the cause. When I was in Gilmer I ripped the ears off of my slipyoke on a spot that wasn't that difficult. I think it is related.

 

[Leper]

Check your motor mounts, I had an 78 with worn out motor mounts and the engine was lifting like 3-4 inches. Have someone powerbrake it while looking at the engine, Good luck.

Replaced them already. The engine wasn't moving much, but that was my thought also.

 

[Cmoe]

Check your u-joints and the drive shaft since you said you smacked it on a rock...... Sounds like draiveshaft vibration.....

 

[Leper]

Check your u-joints and the drive shaft since you said you smacked it on a rock...... Sounds like draiveshaft vibration.....

I didn't smack anything. I just bound up. As I said in my original post, the driveshaft and ujoints have been replaced.

 

[slimlynn1]

I would check your transfer case mount, the rubber tends to wear out. Also check to make sure the crossmember bolts are tight.

 

[PhoenixZorn]

I would check your transfer case mount, the rubber tends to wear out. Also check to make sure the crossmember bolts are tight.

Yes, I have replaced the tcase mount and the engine mounts and the ujoints. None of it helped at all.

you guys don't read very well.... really, suggest something he hasn't done yet.

pull your rear drive shaft, put it on a lathe, and see how straight it is. if it wobbles even a little in the lathe, it will transfer a lot more vibration into your truck. other than that, it looks like you've got most things changed that i would have checked. i know it's way out there, but have you checked your front suspension and steering components for a cause of the steering wobble? it won't fix your t-case slamming into the truck, but it might help.

 

[Fubeca]

Can you actually see the spot it is hitting the floor? Is there a dent underneath? Mine used to make a noise like that but it wasn't hitting the floor. (I still don't know what it was - it went away after I tore out the entire drivetrain and put it back together )

 

[Leper]

Can you actually see the spot it is hitting the floor? Is there a dent underneath?

You can see the spot where it hits. The paint is gone. It is at the edge where the floor and tunnel meet.

 

[txfiremank5]

When my cv went out on my front d shaft in my 77 it caused the shifter to shake like crazy... and would sometimes pop it out of lo.

There may enough force on it to tweak the case up a bit..


I can't see how gears would be the problem at all.

 

[Leper]

you guys don't read very well.... really, suggest something he hasn't done yet.

pull your rear drive shaft, put it on a lathe, and see how straight it is. if it wobbles even a little in the lathe, it will transfer a lot more vibration into your truck. .

The driveshaft that is in the truck is different than the one I took out a few days ago. I had a used one retubed and balanced. And replaced the ujoints again.
The only think I am concerned with, right now, is why it moves so much.

How much does a transfer case move at the tailshaft on other trucks? My sons 79 K5 doesn't seem to move at all, especially compared to mine.
Thanks for the help so far guys.
Best Princess Leiha voice "Help me CK5 you're my only hope"

 

[Leper]

When my cv went out on my front d shaft in my 77 it caused the shifter to shake like crazy... and would sometimes pop it out of lo.

There may enough force on it to tweak the case up a bit..


I can't see how gears would be the problem at all.

My problem is less noticiable in 4WD. It is on take off from a stop only. And it lasts for about 2-3 seconds. Once rolling it goes away.

What about a rear pinion bearing? If it was going bad, is it possible for it to side load(push to one side)?

 

[85mudblazin]

Yep mine does the EXACT same thing. But only when I get on it pretty good from a stop or if I go easy on it, it will do it when it shifts into 2nd. My motor and t-case mounts are good.
I have no explination for it beside its maybe just worn out body mount bushings (althought mine are in good shape). My t-case is in the stock position so that isnt a issue.

ANOTHER thing that I thought it might be is my rear driveshaft has a pretty good angle on it with the t-case in stock position so I run a CV in the rear for it. I am thinking that with the 208 slip yoke that when you get on it or when it shifts it tries to slip the driveshaft into the case like normal, but I have so much axle wrap from my rear 56's that it tries to push it in alot more. The 208 slip must not be slipping like its supposed to which would cause the t-case to get pushed up with force, in turn hitting the floor.

 

[koldsimer]

It seems nobody can fix your problem. I have seen this firsthand and I cannot explain it. The tail of the tcase appears to be the only thing moving when it happens. I dont think it's a bad internal bearing because it would be your slip yoke flopping around more. The only way to rule out the tcase is to pull it and dissasemble though... no fun. Last I looked, the body mounts looked near perfect. Plus, you can SEE the case flopping, not the body sinking or flexing. It does it with both driveshafts and your angles look good to me. Did it change at all after you put that cage on it? Could it be something in your torque converter? With those high gears and 35's.... any auto transission experts know if this would be possible? I still think part of it has to do with that goofy tranny mount. It seems like it would flex up and down a lot. I'm sure someone would have experienced this though and nobody has chimed in on it so... good luck man! Oh yeah, you should just let me beat the hell out of the spot where it hits..... problem solved

 

[90K5]

tcase bolts...mine did it too...seems someone thought it didnt need them...

 

[Leper]

Yep mine does the EXACT same thing.
ANOTHER thing that I thought it might be is my rear driveshaft has a pretty good angle on it with the t-case in stock position so I run a CV in the rear for it. I am thinking that with the 208 slip yoke that when you get on it or when it shifts it tries to slip the driveshaft into the case like normal, but I have so much axle wrap from my rear 56's that it tries to push it in alot more. The 208 slip must not be slipping like its supposed to which would cause the t-case to get pushed up with force, in turn hitting the floor.

OK, although my angles are the same, they are pretty steep. I have not changed the angle at the pinion since I got the shaft remade. The slip yoke not slipping was something that led me to have the dshaft lengthened. I will remove my 6* shim and see what happens. You may be on to something here. Thanks

 

[Leper]

tcase bolts...mine did it too...seems someone thought it didnt need them...

Tightened them 2 days ago. They were a little loose but nothing major. Didn't help the problem. Thanks

 

[6.2Blazer]

My '90 with a 241 t-case has the exact same issue. You can see the contact mark on the floor where one of the ears on the housing contacts it.

Mine has new poly engine mounts, t-case mounts, and new poly body mounts.