Hey Vortec Guys! / Sierra pickup / Suburban / Yukon etc - Finally has Index!
- Thread starter rayra
- Start date
rho
Lost again
Welp, I got roped into helping a friend go through and fix some things on his GMT800 Yukon that gets used as a chase/support truck for large gravel cycling events. The truck ends up hauling a bunch of gear and people for these evens as well as getting driven really hard offroad (Read, crazydre or pre-runner type usage). The poor suspension is totally worked over on this beast, rancho lift with LCA/torsion bar drop... which isn't the way I'd have lifted a truck like this, but its not mine and the lift was on this truck when my buddy bought it...
The current plan is to dive into some of the suspension/maintenance items right off the bat, in addition to trying to figure out the 4wd actuator getting stuck in 4wd and blowing fuses.
so far...
-fix 4wd stuff
-fix from sway bar bushings/linkage and contact points (it current looks like it hits the frame which is why the other bushings failed. YIKE)
-front hub replacement
-rear brake line loose/contact
-new shocks all around (I'm looking at bilstien 5160's for this, given how its driven)
-figure out how to improve the front bump stop situation
The upside is he's paying me for this and for parts, downside is well, its a bunch of broken stuff on a modified truck with an unknown history that sees a lot of abuse. The truck is getting dropped off to me Thursday I'm hoping its finished by Sun. So.... I expect to have a lot of questions pop up here in the next few days, LOL.
The current plan is to dive into some of the suspension/maintenance items right off the bat, in addition to trying to figure out the 4wd actuator getting stuck in 4wd and blowing fuses.
so far...
-fix 4wd stuff
-fix from sway bar bushings/linkage and contact points (it current looks like it hits the frame which is why the other bushings failed. YIKE)
-front hub replacement
-rear brake line loose/contact
-new shocks all around (I'm looking at bilstien 5160's for this, given how its driven)
-figure out how to improve the front bump stop situation
The upside is he's paying me for this and for parts, downside is well, its a bunch of broken stuff on a modified truck with an unknown history that sees a lot of abuse. The truck is getting dropped off to me Thursday I'm hoping its finished by Sun. So.... I expect to have a lot of questions pop up here in the next few days, LOL.
rayra
Expedition Leader
Blowing fuses with a stuck actuator is a new one to me. They just get stuck without blowing fuses, far as I know. If it's sticking that hard that it keeps trying until a fuse blows, then the actuator circuit / electrical part of the mechanism is likely working but it's a solenoid so the moving part is likely corroded and hanging. A replacement actuator is ~$80 (dorman) or $100-130 for a Delco part via rockauto.com. But it's too late for them if you are getting the vehicle tomorrow with a short turnaround, unless you pay for express shipping. Which would probably still be FAR cheaper than going to your local GM dealer.
'sway bar hits the frame' ? It's typically mounted to the frame, with its ends attached to the lower control arms via the end links. Not sure how they do it with a drop-lift.
Make sure the shocks are properly sized for the lift or they'll get damaged at max extension. OR if too long, blown out at max compression. The front bump stop is two places, the 'beehive' shaped foam-rubber stop that's frame-mounted and hits a circular landing pad on the lower control arm during max compression and the stop that's a steel extension of the frame rail which the upper control arm contacts at full extension / droop. They make OEM-ish upper replacements with bushings offset to gain a couple degrees of camber, which might help avoid some stop contact. But you'll either have to spend a lot more money for aftermarket off-road -focused arms or cut / modify that frame stop to allow more droop before contact. But that again changes range of motion and impacts other parts so you can't just hack at it.
'sway bar hits the frame' ? It's typically mounted to the frame, with its ends attached to the lower control arms via the end links. Not sure how they do it with a drop-lift.
Make sure the shocks are properly sized for the lift or they'll get damaged at max extension. OR if too long, blown out at max compression. The front bump stop is two places, the 'beehive' shaped foam-rubber stop that's frame-mounted and hits a circular landing pad on the lower control arm during max compression and the stop that's a steel extension of the frame rail which the upper control arm contacts at full extension / droop. They make OEM-ish upper replacements with bushings offset to gain a couple degrees of camber, which might help avoid some stop contact. But you'll either have to spend a lot more money for aftermarket off-road -focused arms or cut / modify that frame stop to allow more droop before contact. But that again changes range of motion and impacts other parts so you can't just hack at it.
rho
Lost again
Yeah.... I have some pics I'll throw up here in a bit, its messy!
rho
Lost again
The bits between the green arrows have some witness marks in other photos I have of contact, plus a shredded swaybar bushing and bracket is behind all of that.
I think its a 4" rancho lift, I'm sure there is more stuff I'm going find when I start really digging into this thing. Short list is shocks, front hub, bits to re-attach the sway bay and MAYBE start digging into the geometry of the sway bar as it looks like stuff contacting there when the front bottoms out.
I'm also going to be going through and checking out all the bushings, ball joints, steering linkages and seeing what else is broke on this thing.
I don't know ****** is going on with this bump stop situation. The one in the factory location is clearly not being used anymore, The lower one on the lift subframe is ??? not sure whats going on with that one but I'm going to look at it when the truck gets to my place tomorrow.
The shocks all around are pretty much toast, at least one of the rears is totally blown and the others aren't in great shape anymore. Given the abuse this truck sees and the speed it'll be subject to I want to try some Bilstien 5160's in it as it sees 4-6 people for high speed in the dirt for long periods of time. I'm not sure what else is out there for affordable options that'll hold up in this situation, but I keep hearing good things about the 5160s.
I'm not a fan of those two wires going into the frame rail there, I'm going to want to put some abrasion protection there I think, but I have bigger concerns with this truck to address before that. This truck also had a G80 in the rear that was blown up by a little too much throttle and water in a river crossing in Utah last year and we gave Murph a TON of crap over it.
Generally I don't like the idea of subframe lifts as a concept for a truck that is going to see heavy off road use as it just opens a bunch of weird ways for stuff to break when its driven hard or when a truck sees hundreds of miles of off road driving a day.
I think its a 4" rancho lift, I'm sure there is more stuff I'm going find when I start really digging into this thing. Short list is shocks, front hub, bits to re-attach the sway bay and MAYBE start digging into the geometry of the sway bar as it looks like stuff contacting there when the front bottoms out.
I'm also going to be going through and checking out all the bushings, ball joints, steering linkages and seeing what else is broke on this thing.
I don't know ****** is going on with this bump stop situation. The one in the factory location is clearly not being used anymore, The lower one on the lift subframe is ??? not sure whats going on with that one but I'm going to look at it when the truck gets to my place tomorrow.
The shocks all around are pretty much toast, at least one of the rears is totally blown and the others aren't in great shape anymore. Given the abuse this truck sees and the speed it'll be subject to I want to try some Bilstien 5160's in it as it sees 4-6 people for high speed in the dirt for long periods of time. I'm not sure what else is out there for affordable options that'll hold up in this situation, but I keep hearing good things about the 5160s.
I'm not a fan of those two wires going into the frame rail there, I'm going to want to put some abrasion protection there I think, but I have bigger concerns with this truck to address before that. This truck also had a G80 in the rear that was blown up by a little too much throttle and water in a river crossing in Utah last year and we gave Murph a TON of crap over it.
Generally I don't like the idea of subframe lifts as a concept for a truck that is going to see heavy off road use as it just opens a bunch of weird ways for stuff to break when its driven hard or when a truck sees hundreds of miles of off road driving a day.
rayra
Expedition Leader
Well they're certainly driving it too hard. Does the guy know how to use momentum rather than just keeping his foot in it? The G80 break is a classic sign of the latter.
From the pic of the front end it's obviously been bottomed out hard repeatedly. The lower arm rammed upward, the end link transmitting that to the sway bar, the sway bar slamming into the upper control mount extension and the force having nowhere to go except prying the sway bar against its frame mount so hard that it failed.
That sway is in the factory frame mount*, while the lower is repositioned lower via the drop-lift's replacement crossmember. Which is hanging from factory crossmember mounts - whose ends form the factory lower bump-stop mount.
They've put their generic bolt-in bump stop mound in there and unfortunately it's just about the same gap as the factory spacing to the bump stop - but the factory is a 3-4" tall beehive looking thing with a lot more smush than that thin rancho part. They probably should have engineered their subframe to allow repositioning the factory bumpstop.
re the sway bar, the end links looks tall and probably is taller than stock and I'm guessing it might be just as much longer than factory as the number of inches that drop- crossmember adds. And I'm also figuring that it probably shouldn't be. Maybe needs re-engineering.
With the shock and torsion bar out, and the end links out on both sides and the sway bar mount straps replaced, jack up the lower control arm to full stop then pivot the sway bar to within a finger's width of the upper mount and measure the distance between the sway bar end and the bolt hole in the lower.
Then drop the lower to full droop and pivot the sway bar until it is close to the tie rod and again measure. Your end link length needs to be at or taller than the last measurement and at or shorter than the first measurement. Something between the two measurements.
And if it is being driven like a pre-runner - which it isn't meant to be, the vehicle is pretty heavy for what it is - I'm surprised they haven't been bending the tie rods. There's cheap and expensive ways to beef those up. And that tie rod end link clearance ought to be adjusted for those, too.
*I'd thought such drop-lifts moved those mounts downward too, but there's very little room to do so.
I also notice that they routed the ABS sensor cable up the wrong side of the upper control arm, it's supposed to go thru that empty clip above the rearmost upper mount, between the shock and those horribly routed battery cables. Savvy to put them inside the frame but wth with the no chafing guard?
It doesn't really matter which side the ABS wirings goes, it clips to the harness up above and inboard of the shock top, but the way they're smashing the sway bar into the frame, they're lucky that's stopping the ABS cable or the brake line from getting chewed up too. Especially as the factory brake line clip positions the line between the control arm and sway bar end.
eta I'm invoking a magic spell to get some more expert help for upgrades/mods, my stuff's stock / inexpensive
@Stryder106
@Burb One
From the pic of the front end it's obviously been bottomed out hard repeatedly. The lower arm rammed upward, the end link transmitting that to the sway bar, the sway bar slamming into the upper control mount extension and the force having nowhere to go except prying the sway bar against its frame mount so hard that it failed.
That sway is in the factory frame mount*, while the lower is repositioned lower via the drop-lift's replacement crossmember. Which is hanging from factory crossmember mounts - whose ends form the factory lower bump-stop mount.
They've put their generic bolt-in bump stop mound in there and unfortunately it's just about the same gap as the factory spacing to the bump stop - but the factory is a 3-4" tall beehive looking thing with a lot more smush than that thin rancho part. They probably should have engineered their subframe to allow repositioning the factory bumpstop.
re the sway bar, the end links looks tall and probably is taller than stock and I'm guessing it might be just as much longer than factory as the number of inches that drop- crossmember adds. And I'm also figuring that it probably shouldn't be. Maybe needs re-engineering.
With the shock and torsion bar out, and the end links out on both sides and the sway bar mount straps replaced, jack up the lower control arm to full stop then pivot the sway bar to within a finger's width of the upper mount and measure the distance between the sway bar end and the bolt hole in the lower.
Then drop the lower to full droop and pivot the sway bar until it is close to the tie rod and again measure. Your end link length needs to be at or taller than the last measurement and at or shorter than the first measurement. Something between the two measurements.
And if it is being driven like a pre-runner - which it isn't meant to be, the vehicle is pretty heavy for what it is - I'm surprised they haven't been bending the tie rods. There's cheap and expensive ways to beef those up. And that tie rod end link clearance ought to be adjusted for those, too.
*I'd thought such drop-lifts moved those mounts downward too, but there's very little room to do so.
I also notice that they routed the ABS sensor cable up the wrong side of the upper control arm, it's supposed to go thru that empty clip above the rearmost upper mount, between the shock and those horribly routed battery cables. Savvy to put them inside the frame but wth with the no chafing guard?
It doesn't really matter which side the ABS wirings goes, it clips to the harness up above and inboard of the shock top, but the way they're smashing the sway bar into the frame, they're lucky that's stopping the ABS cable or the brake line from getting chewed up too. Especially as the factory brake line clip positions the line between the control arm and sway bar end.
eta I'm invoking a magic spell to get some more expert help for upgrades/mods, my stuff's stock / inexpensive
@Stryder106
@Burb One
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rho
Lost again
Yep... a lot of this, esp with bump stop locations and swaybar/endlinks re-engineering is in the plan to do already.
And yah, I've been giving him a TON of crap about slowing down and how to drive this truck better in nasty stuff. I'm seriously considering seeing if i can dig up a knuckle and ditch the diff drop to take this back to stock-ish... then do a torsion key lift with better bumps and longer shocks and more down travel. And taking a sawzall to the fenders as it runs 305/70/17 tires on it.
Yeah... I hate these diff drop kits for the GM trucks. They're just SO BAD. All of them. At least the yota guys seemed to have figured them out.
rayra
Expedition Leader
rho that's been true since the 80s. Lot of these kits are 'good enough' and for looks, just like the triple-tube "roll bars" of the 80s which had nothing but a piece of plate steel bolted to the sheet metal bed. But there are lots of companies doing a better job of it these days. I just poked Stryder106 and BurbOne in the earlier post above to get their attention. Those guys have done a lot more modding and with much higher end parts. Talk with them and they can very likely steer you to some better recommendations for upgrades. But they might not see this in time to help with this weekend.
That stuff's way out of my hobby budget so I don't really read up on it much. I've just been farting around off-road in all sorts of mildly modded factory production vehicles and owning driving Tahoes since '99 and Sub since ~5yrs ago. I've broken and wrenched on a lot of stuff from crappy old mini trucks and baja bugs thru 2-, 3- and 4-wheel ATVs and Jeeps and full size pickups. Mountains, deserts, mud pits. Got stuck and unstuck with rudimentary gear more times than I can count. I've hacked together a lot of low-budget mods in those early years, too. And I wrench on just about everything I can which doesn't require very expensive tools. That's part of why I started this topic in the first place.
That stuff's way out of my hobby budget so I don't really read up on it much. I've just been farting around off-road in all sorts of mildly modded factory production vehicles and owning driving Tahoes since '99 and Sub since ~5yrs ago. I've broken and wrenched on a lot of stuff from crappy old mini trucks and baja bugs thru 2-, 3- and 4-wheel ATVs and Jeeps and full size pickups. Mountains, deserts, mud pits. Got stuck and unstuck with rudimentary gear more times than I can count. I've hacked together a lot of low-budget mods in those early years, too. And I wrench on just about everything I can which doesn't require very expensive tools. That's part of why I started this topic in the first place.
rho
Lost again
Yeah. I hear ya. I've had a old 4x4 Dodge Dakota, 2 XJs, my JKU and my partners Sierra and had great luck with all of them. My JKU is the most modified out of the bunch but all got me through a lot of places. And that 2wd Sierra gets a shocking amount of places with air pressure and the locker. I also run the most trails on the JKU, but for a truck like this I'm working on... and yah. It currently doesn't have an off-road ready suspension in my opinion.
Anyways. I'm getting the truck this afternoon, I ordered the first round of parts I'm comfortable ordering and the longest lead items (4x4 stuff and shocks) and I'm going to go through it with a fine tooth comb and make a list of rec's to ensure that this becomes a reliable truck for his needs. I'm going to go look into those threads when I have some time tonight as well.
I'm starting to formulate a plan around the following for future work on this truck: Ditch the diff drop kit, get get longer travel UCAs and figure out how to deal with the swaybar. strengthen the tierods and get better bumpstops that are set to work the shock height. I suspect adding limit straps to this would be a good idea as well depending on how much travel we can end up getting with it.
I suspect the torsion bars/CV's end up being the limiting factors there, but we'll see once I can start measuring stuff and getting actual data.
Buddha.
Finally in expo white.
Every time I think about dropping some coin to make my truck more off road worthy I have to remind myself that I don’t actually off road and I need my rig to be able to tow 10k pounds, off road gear isn’t gonna help me.
So I just live vicariously through threads like this.
So I just live vicariously through threads like this.
rho
Lost again
So I got the truck today, took it for a test drive and generally romped around on it. It drives pretty good without a front swaybar! haha.
I got some new bushings/brackets for the swaybar and i'm going to start looking into part numbers for bump stops that I can re-purpose for the front lower bumps as they're maybe a 1/4 of hard urethane. Sigh. Got new tie rod ends as the ones on there are shot. Front hub is shot.
Also started looking into the 4WD issues, played around with it and it blew a fuse or two right off the bat... Got it out of 4WD eventually, popped the dash switch unit out and poked it with a meter and cleaned up the PCB contacts for the buttons, then put it all back together... then stuck a 30A and that didn't blow.... Then backed it down to 15A and that didn't blow.
So my new is to pull the whole transfer-case actuator and the solenoid on the front diff and see whats up with both of em internally as well as pull that switch panel out again and get it cleaned and generally give everything the standard refurb electronics treatment.
I also got under it a bit, there is a lot of wiring that I'm going to have to re-route and sort re-secure.
All in all its a bit less bad than I was expecting.
I got some new bushings/brackets for the swaybar and i'm going to start looking into part numbers for bump stops that I can re-purpose for the front lower bumps as they're maybe a 1/4 of hard urethane. Sigh. Got new tie rod ends as the ones on there are shot. Front hub is shot.
Also started looking into the 4WD issues, played around with it and it blew a fuse or two right off the bat... Got it out of 4WD eventually, popped the dash switch unit out and poked it with a meter and cleaned up the PCB contacts for the buttons, then put it all back together... then stuck a 30A and that didn't blow.... Then backed it down to 15A and that didn't blow.
So my new is to pull the whole transfer-case actuator and the solenoid on the front diff and see whats up with both of em internally as well as pull that switch panel out again and get it cleaned and generally give everything the standard refurb electronics treatment.
I also got under it a bit, there is a lot of wiring that I'm going to have to re-route and sort re-secure.
All in all its a bit less bad than I was expecting.
rayra
Expedition Leader
"I suspect the torsion bars/CV's end up being the limiting factors there, but we'll see once I can start measuring stuff and getting actual data. "
You might be able to keep the drop-lift if you just cut and re-make the lower control arm bump stop clearances. And do something about the upper bump stop locations.
I really don't know that the best or decent aftermarket 'off road' upper replacement arms are @Stryder106
I presume that with the drop-crossmember they also added the drop-crossmember to reposition the torsion bars and keep their similar angle with the lower arms. That should have the torsion bars passing under and free of the factory pass-thrus in the transmission mount crossmember / transfer skidplate mounting location. So they shouldn't give too much grief on vertical travel with things mostly as they are right now. Given the slamming around the vehicle has been getting, I'd be giving the torsion bar adjuster crossmember / replacement a good looking over as well, it's probably tore up / bent.
Too, look for damage to the panard bar and impacts by the rear sway against the diff cover and broken rear control links on the sway. None of that stuff is meant to be raised very far without modifications or aftermarket replacement parts.
You might be able to keep the drop-lift if you just cut and re-make the lower control arm bump stop clearances. And do something about the upper bump stop locations.
I really don't know that the best or decent aftermarket 'off road' upper replacement arms are @Stryder106
I presume that with the drop-crossmember they also added the drop-crossmember to reposition the torsion bars and keep their similar angle with the lower arms. That should have the torsion bars passing under and free of the factory pass-thrus in the transmission mount crossmember / transfer skidplate mounting location. So they shouldn't give too much grief on vertical travel with things mostly as they are right now. Given the slamming around the vehicle has been getting, I'd be giving the torsion bar adjuster crossmember / replacement a good looking over as well, it's probably tore up / bent.
Too, look for damage to the panard bar and impacts by the rear sway against the diff cover and broken rear control links on the sway. None of that stuff is meant to be raised very far without modifications or aftermarket replacement parts.
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