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Loose bolts

Magikal

Magikal

1/2 ton status
Joined
Nov 25, 2007
Posts
402
Reaction score
103
Location
North Idaho
7.4l/4L80E/203/205

Problem: the 6 bolts connecting my adapter from tranny to the 203 keep coming loose and falling out. I've replaced the bolts, used loctite (blue), made sure the bolts were as long as i could fit (around an inch of thread engagement), they torque down to a couple ugga-duggas tight and seem secure. This last time they only lasted a couple of mild wheeling trips before they were all gone again. All my mounts are the same material, rubber. I'm off road only so no highway speeds.

Anyone else have this issue? I'm thinking that the bolt holes in the 203 are worn. Enough to tighten up but not getting full thread engagement?

Proposed solution:

Step up bolt size and go with a fine thread.

Or

Switch to studs and red loctite or tack weld them bitches in.

Or

Heliocoil


Open to suggestions also.
 
I read your post twice, but I have to ask, are you using lock washers of any kind?
Maybe good lock washers or Nord lock washers and blue loctite? I assume that you are cleaning the bolt holes well with brake clean and compressed air before loctite.
 
6872xtc said:
I read your post twice, but I have to ask, are you using lock washers of any kind?
Maybe good lock washers or Nord lock washers and blue loctite? I assume that you are cleaning the bolt holes well with brake clean and compressed air before loctite.
Click to expand...
Tried various lock washers. This last time i actually used a hardened flange bolt. They went quicker then any.
 
Guess I'm gonna have to drop that doubler out so i can get a good vantage on the threads, etc. Hard to see anything installed. Grateful they are not shearing off i suppose. Ughhh....
 
Mounts are all soft rubber. Plenty of give for twisting.

I'm thinking studs sounds like a good idea. Install once well and leave that connection alone

I'm about ready to just weld adapter to the 203 and be done
 
lots of 205 and 203 units i have broke down for parts have had a blue or yellow locktight and even star washers for locks .
 
Ok guys, here is my plan. I decided that I'm gonna try putting studs in with red loctite, using the same thread size as i have now, 3/8-16. I got the flange nuts with the serrated bottoms and a lock nut to go above that. I can install these without removing the doubler. If these don't do the job i can assume that the threaded holes are shot at which point i will remove the doubler and retap the holes a size bigger with a fine thread. I figure i got nothing to lose by trying this. I really don't want to pull the doubler right now as it's spring breakup here in North Idaho. You can barely stand on the ground without sinking. My driveway is a 2 mile mud pit, dragging axles most of the way on 33s on my daily driver.... uphill both ways....lol.

Anyways, I'll get those installed today or tomorrow and go beat the hell out of it for a bit and I'll post up results in a few days.
 
I had a similar situation years ago that drove me nuts. 78 K5, 350 small block, th350 transmission, np203 transfer case, add-a-leafs on front, 3" blocks on rear, 33's. Kept having the bellhousing bolts back off. Also had it breaking the bellhousing on the trans. Tried lockwashers and loctite. Couldn't figure it out.

Ended up being a combination of trans mounts and drive shaft. The transmission mounts were oil soaked and spongy soft. The drive shaft was getting worn. Because of the lift (and the fact that i was a broke college kid who didn't extend the driveshaft), the driveshaft splines didn't have a lot of engagement.

The result was that driveshaft was moving in and elliptical kinda of wobble. And this was causing the transfer case to shake on the soft mounts. And this was breaking the bellhousing/loosening the bolts.

The driveshaft got rebuilt. Replaced transmission mounts. Never did it again, but the truck got parked not long after, so can't be 100% sure.
 
I can't help myself, it's burning a hole on my keyboard. According to this engineer, most lockwashers are trash. It's a good read, but don't hate the messenger, I'm just passing on what sounds like well supported facts:

engineerdog.com

10 Tricks Engineers Need to Know About Fasteners

You’d expect an engineer to know everything about a basic subject like nuts and bolts right? Well fasteners are one of those topics that seem simple at first but turn out to have much more depth th…
engineerdog.com engineerdog.com
 
Try nylon patch screws - Mcmaster car has all of them. Run a plain flat washer under the head. See what happens. Otherwise locktite some studs in and use locknuts. Are the mating surfaces flat? Are you using a gasket or just RTV or something else?
 
anwat said:
I can't help myself, it's burning a hole on my keyboard. According to this engineer, most lockwashers are trash. It's a good read, but don't hate the messenger, I'm just passing on what sounds like well supported facts:

engineerdog.com

10 Tricks Engineers Need to Know About Fasteners

You’d expect an engineer to know everything about a basic subject like nuts and bolts right? Well fasteners are one of those topics that seem simple at first but turn out to have much more depth th…
engineerdog.com engineerdog.com
Click to expand...
Yeah, the research I've done also concluded that washers are not good either.
 
eric67camino said:
I had a similar situation years ago that drove me nuts. 78 K5, 350 small block, th350 transmission, np203 transfer case, add-a-leafs on front, 3" blocks on rear, 33's. Kept having the bellhousing bolts back off. Also had it breaking the bellhousing on the trans. Tried lockwashers and loctite. Couldn't figure it out.

Ended up being a combination of trans mounts and drive shaft. The transmission mounts were oil soaked and spongy soft. The drive shaft was getting worn. Because of the lift (and the fact that i was a broke college kid who didn't extend the driveshaft), the driveshaft splines didn't have a lot of engagement.

The result was that driveshaft was moving in and elliptical kinda of wobble. And this was causing the transfer case to shake on the soft mounts. And this was breaking the bellhousing/loosening the bolts.

The driveshaft got rebuilt. Replaced transmission mounts. Never did it again, but the truck got parked not long after, so can't be 100% sure.
Click to expand...
I could be having a similar situation. I know my rear mount is quite soft. Front ones aren't any better. Driveline is homemade but im off road low speeds (less then 30mph 99% of the time) and never see highway speeds. I've never had an issue before with it over many years wheeling.

We'll see how the studs and loctite work out. Hopefully install them tomorrow.
 
I had the same issue with my doubler switched to studs and fine thread red loctite everything I beat the crap out of my rig . When I was using bolts they would constantly come loose and even had to swap cases due to the bolts wollering out the threaded holes seems to be working great now also makes
Pulling it in and out easier .
 
Chevk587 said:
I had the same issue with my doubler switched to studs and fine thread red loctite everything I beat the crap out of my rig . When I was using bolts they would constantly come loose and even had to swap cases due to the bolts wollering out the threaded holes seems to be working great now also makes
Pulling it in and out easier .
Click to expand...
That's encouraging. So i went to put stock size studs in. First one threaded in but when i tried to tighten it up and it just skipped the threads/ stripped. Tried a second one and same result. Guess the holes are shot. Gonna remove the doubler and step up to a size larger and fine threaded studs with the red loctite. Debating doing a rebuild on the 205. It's never been done that i know of and the output shaft seals seep already. Where's the goto place for rebuild kits these days?
 
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