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Just getting started - '87 K5

jtrux

1/2 ton status
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Jan 14, 2007
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Location
San Antonio, TX
I've been a member for a little while now. It started with the purchase of my '71 K5. Now I'm the owner of an '87 K5 (305/700R4/NP208/stock axles/4" lift/35's) that I originally bought to fix up for my brother but decided to get him something a little more economical so now I have it.

I've never wheeled a fullsize ( I also own an '06 Unlimited ) so the whole experience is new to me and the mods associated with it are foreign, as well.

I'm not completely sure where it will end up but I have an idea. I know that most people tell you to strip it down and build it right the first time with 1 ton axles, giant tires and a plethora of other expensive and often time consuming mods but I just don't have the room to do that right now. Too many other vehicles taking up floor space and quite frankly, I really don't want to do it. I've been super busy with work the last few years and I've had virtually no time to get out do the things I've been wanting to do so it makes more sense for me to just use it as is and take advantage of the current mods that it has until it becomes more feasible to do major modifications. I'm not trying to race in King of the Hammers, just want to get out and run some trails and meet new people. Sounds simple enough.

Sooooo first things first...determining whether or not this thing is even roadworthy. It's spent the majority of its time with me sitting at my parent's place (like I said, I have pretty much no room at my house other than just a place to park it) and I haven't really had the opportunity to give it any break-down runs. I did rebuild the tranny right away when I first got it, as well as a few other odds and ends but I never spent much time behind the wheel other than loading it on and off my trailer.

Before I bring it home I wanted to make sure it was gonna be even worth messing with. I went out to my parent's tonight, put a battery in it and drove it around. Started up relatively easily and shifted through the gears fine. It does have a pretty serious leak and it appears to be coming from the front the front pump seal. I'll need to address that. I hate leaks.

Oh, before I continue, I'm currently at work and do not want to get too brave and start going into photobucket and so forth. I know it's pretty benign but I'd rather be safe than sorry. I will upload pics at a later time when I'm at home.

Oh, the only good glass on it is the top glass (sliding windows). All other windows are busted or cracked in one way or another. Hail storm is responsible for some of it and a young punk shot out another window, too. Oh well, I plan on removing the doors and going topless anyways.

Here's the immediate issue. Guess I could have said this from the start but part of my test run was ensuring that the 4WD worked. I engaged it and went creepy crawling around the property. I found a tree that had fallen and decided to get to flexin' on it. It went up effortlessly but just about as soon as I start to "feel" the flex, the fan went completely ape sh!t on the shroud. I backed off and looked under the hood at where it was hitting and could see a freshly worn spot on the shroud. I pushed it up the tree again and eased it a little further and cut it off. Got out again and verified that it is indeed rubbing the shroud. I also noticed that the bumper was pretty drastically out of alignment with the front clip, too.

Obviously, that has to be addressed since flex is a major component of wheeling. What are you guys doing to address this? Stiff front bumper (mine is stock)? Aftermarket engine crossmember (ORD's)? I am sure that boxing the frame would cure this but I'd much rather not get into that right now. Electric fan?

This is the first obstacle I've encountered and I'm glad I discovered it before dragging the damn thing two hours away to wheel it. Once this is addressed, I'll move onto the leaks and so forth. I know it won't be perfect before I take it out but I want to try and alleviate any obvious issues.

Thanks for putting up with my long post and I promise I'll post pics soon.
 
Oh, one other thing that came to mind afterwards, are any of you guys running cable shifter for your autos? I haven't had an issue yet but I figured that if the body is flexing that much, it's very likely that the shifter linkage could bind, as well.
 
Would agree with the body mounts being an issue, also motor mounts at this age. Just something to look at. The core support body mounts seem to be a fairly common issue, as far as that stuff goes.

I've never heard of people having issues with the stock shifter when wheeling with the auto, although maybe I just haven't been paying attention. Thinking about it, if the shifting mechanism is not tied into the frame up by the motor (and I don't believe it is, only pivot point next to the trans?) flex is most likely not an issue.
 
I know that most people tell you to strip it down and build it right the first time with 1 ton axles, giant tires and a plethora of other expensive and often time consuming mods

Nah. These things were popular because they were very capable even in stock form. Your 1/2 ton drivetrain will do fine up to about 35" tires or so. I say get it running reliably and just fix stuff as it breaks. Especially if you're going to strip it down to an offroader. All the weight you can remove (doors, interior, etc) just helps take load off your drivetrain. Mine ran with 35s for 10 years with 1/2 ton gear. I should note that it did break the diff twice in that time and now has 1-tons. But I still say for recreational use, as long as you don't get crazy, it'll do fine.

As for the flex, everybody is right - body mounts.
 
It will flex a lot more with no doors,so maybe adding some type of truss bars inside the cab and bed wont hurt!...

I "wheeled" my '72 K5 once with the top off and no doors,and when I put them back on--I couldn't get them to close!..had to do some major tweaking to get them to work again,then fix all the rusted areas on the floors...and I never tried taking it off road without the top on it or the doors off it again...even though I beefed up the floors a lot compared to what it was stock..
 
Yea, I recall taking my '71 out a few times with similar issues.

Here's two pics of some sexy flexin'. Lol

The fan was destroying the shroud in these pics so I killed it, jumped out and snapped a pic from each side.



 
I was looking at cages. I wouldn't mind having a pickup cage in it and leaving the passenger area exposed. I don't plan on having passengers BUT it would probably help with rigidity overall with the additional support of the rear cage.


I'm really leaning towards chopping the roof, too. I love my '71 and the feel and look of a full convertible 4WD so it's pretty likely that I will go that route. A cage would be necessary in that case.
 
Yea, crazy. I can't imagine body mounts being the issue or even motor mounts but you never know.
 
Yea, crazy. I can't imagine body mounts being the issue or even motor mounts but you never know.

I'd inspect the frame rails closely for any cracking,they sometimes "tear" near the upper shock mounts--also see that all the rivets in the front crossmembers are there and not loose,I've seen a lot of GM 4x4's with them sheared off or stretched and they had to be replaced with grade 8 bolts (most guys welded the members in place permanently)..any truck thats been lifted or seen lots of miles on poor roads can have that issue..2 of mine did...made a big difference when I fixed that...

Also on one truck I had,the tranny crossmember bolts kept stretching and eventually shearing off,someone I found out had not put the upper half of the crossmember back on that connected to the upper frame rail,and they used 3/8" bolts instead of the proper 7/16" ones--the holes in the frame got egged out some,so I drilled them out to 1/2" and used 1/2" bolts,and I was surprised how much better the truck drove and felt after just doing that--it had always had an annoying "pop" sound while cornering or going up a incline off a flat road,that dissapeared after I did that!..

The front core supports often rot around where the rubber biscuits sit and allows them to flop around,and the bolts also like to rust away to nothing inside the rubbers,but look fine from the outside..you may have to add a plate of steel to the core support so the rubbers wont just go thru and let the nose flop around under flex conditions..
 
Yea, I really need to give it a more thorough inspection. Sounds like it is likely a number of issues.
 
A set of poly body mounts, engine mounts, and tranny mounts will do a lot for you.

Also check the area where the steering box mounts to the frame, very common to develop cracks around the bolt holes.
 

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