Edger: The adventures and ramblings of a high mileage 1992 Chevy K1500 RCSB

nitro_rat

On a Suburban Excursion
I think ANY 3/4 ton shaft will be longer than you need. Don't rule out 80's trucks as shaft donors either. The NP208 (and MAYBE turbo 400/4L80E) all use the same slip yoke. Just grab one from a semi-float truck!
 

tdferrero

Active member
Great thread and progress, really enjoying it. Though I must say the M20/M30 are some of the easiest engines to work on. ;)
 

TwinDuro

Active member
Great thread and progress, really enjoying it. Though I must say the M20/M30 are some of the easiest engines to work on. ;)
Thanks @tdferrero and glad you're enjoying it; nice LC100 in your profile photo by the way. I think I haven't quite found my zen with BMW engines yet... 😉 With that said, if money was flying out of my pockets uncontrollably, I'd have a hard time not using some of it on a red E24 M6 or a E9 CS/CSL, as I think those are both jawdroppers in my book.
 

tdferrero

Active member
Thanks @tdferrero and glad you're enjoying it; nice LC100 in your profile photo by the way. I think I haven't quite found my zen with BMW engines yet... 😉 With that said, if money was flying out of my pockets uncontrollably, I'd have a hard time not using some of it on a red E24 M6 or a E9 CS/CSL, as I think those are both jawdroppers in my book.
Thanks a lot! If I ever come across $200,000, an E9 will be the first car I buy without any hesitation. But until then, I’m content with my 1988 E30. 7299CF99-6C0E-4667-BE6E-59C04DB2566E.jpeg
 

TwinDuro

Active member
Nice 'vert @tdferrero!

Alright, back to the K1500. As I mentioned in the first post of this thread, I'm a big fan of using "upgraded" factory parts on vehicles that don't have them. For example, upgrading the radiator, fan shroud and coolant hoses to the larger 34" radiator that was available in HD cooling package vehicles and larger trucks like the K2500/K3500 on my truck with the small (leaking badly) radiator. It fits perfect, doesn't cost much and is a definite upgrade.

On that same note, while shopping Rock Auto, I noticed that a 5-1/2" tall air cleaner is listed for the '92 K1500. I currently have a 3-1/2" air cleaner which is totally fine but makes me curious. Does anyone know what rigs came with the taller "severe duty" single bolt air cleaner housing? My wild ass guess (hereto referred as WAG for the rest of the thread) would be maybe the Z71 package, a 454 equipped truck. If I knew what to look for, I might find the larger housing at the junkyard and I'm always a fan of larger air filters.

Something I learned from racing a stock production type Subaru Rally car with friends in the NORRA Mexican 1000 Rally for several years was how well most factory style air cleaners work at not only filtering the air but in dealing with extreme conditions, like driving through silt beds where it's literally like taking a 55 gallon drum of talcum powder and throwing it into a industrial fan while running full throttle. The factory air cleaner/snorkle on that Subaru did a great job whereas something like a open-element cold air intake would have surely clogged up. I know this truck isn't a Subaru, but I have kind of the same sentiment for Edger here. I know it's often not popular opinion to keep a factory setup, but to me it makes a ton of sense for reliability and parts availability.

Soon, when the front end rebuild starts, I've also considered doing a mild brake upgrade since the current brakes could use some TLC. From what I understand, similar year K2500/K3500 calipers bolt on the stock knuckles and will use the K1500-sized pads. Supposedly this is what the police package 4x4 Tahoes used. The caliper piston is a bit larger (79.9mm vs 74.5mm for the factory K1500 caliper) and that with the 9.5" semi float rear end, 1-3/16" wheel cylinders from a dual-rear wheel truck swap over, supposedly giving better braking power. In theory this makes sense, but reality might be different. Any thoughts?

I've been happy with the braking power and pedal feel of the stock, non-hydroboost brakes and the larger rear drums of the "new" 9.5" 14 bolt SF rear end will help as well, but if I'm replacing parts anyway and it's actually an improvment, why not?
 

TwinDuro

Active member
I'm also excited to show you all the design for the bed drawers I'm going to build. It's a bit different, but very functional. Part of the design includes making a space to put the full size, 285/75-16 spare flat in the bed. Being a regular cab short bed, the under-bed mounted spare is pretty small and the space pretty limited. I'd be surprised if you could fit anything larger then a 245/75R16 (there's currently a 225/75R16) under there without clearance issues, especially with the factory trailer hitch which is absolutely staying since I tow on a regular basis and use it as a recovery point with a hitch-clevis for towing/dragging things periodically. While that tiny spare would get me home no problem, I'm planning on doing some fairly remote trips with this truck and having a full size spare is never a bad idea. With the tire flipped upside down in its spot in the new bed drawer/platform, its also a great place to stash several soft tool/gear bags inside the wheel.

Sure, I could pit the spare on the roof of the canopy (no thanks, been there, done that, too much weight up high, this tire and wheel combo weighs about 80lbs.) or do a rear swing-out (not a bad option, but also not my cup of tea) but instead I'm planning to put the tire in the right front corner of the bed closest to the cab. There will be two separate removable drawers, the right-side unit thats 34-36" wide and 36" deep with a hinged platform that sits directly on top of the spare tire for support (with standoffs if the tire's not in there as well).

The left-side drawer will be about 12" wide and 70" deep. I want to leave about a 9" open space in the rear between the drawers and tailgate for tools, loose stuff or a set of traction ramps or sand ladders when I'm down in Baja or Sonora. Also, when sleeping in there, it allows you a place to put your feet down into to change clothes/etc. That's the idea anyway if this all makes sense. I'll do a quick mock up before I commit to make sure it works.

The idea is that I can also remove the left-side narrow, bed-length drawer out if I'm going solo for a single sleeping platform with more room to sit up and put your feet down.

I'll use 3/4" plywood and the skate-board bearing-3/4" square tube method to make heavy duty slides, use locking "T" latches, seal up all the seams and then give the whole shebang some heavy coats of black deck paint. Done right is should be pretty weatherproof when the canopy's off.

I should be able to build something pretty skookum for not a lot of cash... I really like the design and construction of the DECKED-brand truck bed storage systems but they don't build one specifically for the GMT400 and at around $1,250 after tax, thats about $1000 out of budget. That $1000 would be better spent on

(Post updated on 4/10/20)
 
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nitro_rat

On a Suburban Excursion
Regarding the brakes:

I've found that most of the brake complaints on these trucks stem from the fact that most mechanics can't properly service drum breaks anymore. It's amazing how firm the pedal feel is when the rear brakes are both not worn out and properly adjusted. I always order the big hardware kit with new springs and adjusters when I do drums, it's cheap! Make sure you have some "brake grease," I use the purple stuff from Napa (sparingly please! on the adjuster threads and anywhere there's metal-to-metal contact!).

Fresh fluid and a proper bleed makes a big difference as well!

Now, on to "upgrades:"

1. Hydroboost. This is the single biggest difference that you can do. It dramatically increases the leverage on the hydraulic system. Easy swap with a few junkyard parts.

2. GMT 800 master cylinder. This one is popular on the web but I think the reason is to compensate for poorly adjusted or improperly assembled drum brakes. IMO it's unnecessary.

3. ABS delete. The ABS on these trucks comes in two flavors. 88-94 and 95-99 (or whenever the GMT 400's stopped, a few models lingered thru 2000 or '01 I think). The 95+ system is decent but I still prefer plain old regular brakes over this system. The early system is archaic and terrible (and much easier to delete than the newer system). Plan to spend some quality time with hardline and a tubing bender. You can get an adjustable proportioning valve with a bracket that bolts up to the master cylinder bolts. Makes for a clean install. Check Summit or Jeg's. This makes the system perform better and is much easier to properly bleed!

4. Bigger pistons in the calipers/wheel cylinders. You already know about this one. The results are more dramatic with hydroboost and ABS deleted.

5. Rear disc brakes. Probably not a great performance advantage here especially when talking about the big drums on the 9.5. GMT 800 parts are the most likely source.

6. GMT 800 knuckle swap. It's possible to put the knuckles from a GMT 800 on the GMT 400. I haven't researched this in a while but I think the tie rod end attaches from the opposite side. This can work ok if you're lifted or you can use a tapered reamer to insert it the other way. May be necessary to ream for the lower ball joint too. This opens up some much better/larger rotor/caliper options. Combined with hydroboost this would give the ultimate braking system. In this situation I would recommend the GMT 800 master cylinder! For the big GMT 800 rotors you'll need at least 17" wheels!

I think that covers most of the bases for the GMT 400 1/2 ton brake options...
 

TwinDuro

Active member
Thanks for taking the time to put down all of this great info @nitro_rat! As always, I'm learning a ton.

We're on the same page as far as drum brakes go, it seems like most folks are totally overwhelmed by what they don't understand when it comes to servicing/adjusting drum brakes which is what gives them a bad rap, but I've found that once you understand how they operate, the mystery is gone and they work well when in good shape, like you said. I've been lucky to get a good education on drums since up until recently, all of my family and friends' vehicles had rear drums and sometimes front drums (in the case of a '58 Nash I helped do a full mechanical resto on and a buddy's '66 Plymouth Satellite at first) and no one ever wanted to touch them, so I'd volunteer and the first couple sets were a learning experience but after that I don't blink an eye. I actually really like drum brakes. Like you highlighted, in the past I've made the mistake of using too much "brake grease" to my detriment. 🤣 I keep it light now!

Thankfully ol' Edger is ABS-free from the factory, so I don't have to go down that road! Good to know about the adjustable proportioning valve though, I'll keep that in mind. I installed one of those on the rear drum circuit of my buddy's '66 Satellite after we rebuilt the rear drums and swapped the front disks for waaaaay-overkill Wilwood 4-piston units. It was super nice to be able to dial the rear drums in to be copacetic with the race-car front brakes. 🤣 The current brake fluid in Edger could be a prop stand-in as "bubblin' crude" in the Beverly Hill Billys TV show intro, so a proper bleed to get all that riff-raff out is step one.

On GMT400.com and other sites I've read about the GMT800 master cylinder swap, and it didn't make much sense to me and there were always seemingly holes in the info I was reading, so thanks for clearing that up! If I was to take another WAG, I wonder if the bore sizes different on the GMT800 master cylinder? That's the only thing I can think of other then if the pedal/push-rod ratio is different that would make people claim a big improvement over the factory unit...

Copy that on the hydroboost, good to know and I'm sure its only a matter of time until I do that swap. I'll start with the the larger rear drums, dually 1-3/16" wheel cylinders and larger-piston 3/4/1 ton calipers up front with the factory vacuum booster and see how it feels with fresh rubber brake lines and fluid first. Then I'll keep my eyes open for a junkyard hydroboost setup.

The hydroboost sounds like a winner to me because more frequently as the years pass, I find myself towing rented double-axle car trailers (From U-Haul mostly as its the only choice around here to rent a trailer) with 3-4k pound cars on them. Figure, the car trailer weighs around 2,250 pounds unloaded with an average of a 3,500lb car on it, it's pushing 6000lbs, so the best possible brakes are a must, especially on a shorter wheelbase rig like this. I certainly don't tow loaded trailers like this fast (usually 4th gear on the NV4500 at 55-65mph depending), but when all the upgrades are done, it should be identically equipped like a F44 K1500 or LD K2500.

Good to know about the rear disk and possible GMT800 front knuckle upgrade. Even though it's awfully tempting, with a relativity new set of 16" BFGs, I'll probably stick with brakes that will fit under the 16" wheels.

Thanks again for all the info!
 

nitro_rat

On a Suburban Excursion
I could be mistaken but I'm pretty sure ALL GMT800's have at least rear ABS. It's a pretty small black box by the master cylinder. It's real easy to delete...
 

TwinDuro

Active member
F45E27EA-D4D4-4D41-AA25-14E66A8E25C5.jpeg

@nitro_rat Well I’ll be damned, you’re right! I can’t believe I didn’t realize that; sometimes I’m not the brightest bulb in the light fixture! 😆 I never noticed any signs of the rear ABS functioning (I’m familiar with how intrusive the Dodge ABS systems were in the ‘90s, I hated those) so I figured it just didn’t have it...

I wonder if it even works?
 

tennesseewj

Observer
I'm not sure about all GMT 800 brakes requiring 17" wheels. The OEM wheels on my '03 1500 were definitely 16". It may require a 16" wheel with specific backspacing, though, as I do recall my buddy tried to put 16" GMT400 wheels on his '06 1500 and they did not clear.

At any rate, I have a soft spot in my heart for these GMT400s and I wanted to chime in and say keep this thread up!

Despite the lackluster interiors with maybe the silliest cupholders ever attempted, I still really want a stray GMT400 to show up in my driveway one day.

Sent from my Pixel 2 using Tapatalk
 

nitro_rat

On a Suburban Excursion
View attachment 578692

@nitro_rat Well I’ll be damned, you’re right! I can’t believe I didn’t realize that; sometimes I’m not the brightest bulb in the light fixture! 😆 I never noticed any signs of the rear ABS functioning (I’m familiar with how intrusive the Dodge ABS systems were in the ‘90s, I hated those) so I figured it just didn’t have it...

I wonder if it even works?
It's probably dead. It's presence can make it difficult to get the rear brake circuit bled properly! I'd can it...

I'm not sure about all GMT 800 brakes requiring 17" wheels. The OEM wheels on my '03 1500 were definitely 16". It may require a 16" wheel with specific backspacing, though, as I do recall my buddy tried to put 16" GMT400 wheels on his '06 1500 and they did not clear.

At any rate, I have a soft spot in my heart for these GMT400s and I wanted to chime in and say keep this thread up!

Despite the lackluster interiors with maybe the silliest cupholders ever attempted, I still really want a stray GMT400 to show up in my driveway one day.

Sent from my Pixel 2 using Tapatalk
True, the early GMT800 brakes cleared 16" wheels. You're giving up half the reason to do such an extensive swap if you don't use the big ones though! The calipers on the 800 are better than the old style ones on the 400 even if you keep the small early brakes. Just make sure to match them with the proper master cylinder. Early pickups still had drums in the rear. Later stuff and SUV's were disc all around.
 
True, the early GMT800 brakes cleared 16" wheels. You're giving up half the reason to do such an extensive swap if you don't use the big ones though! The calipers on the 800 are better than the old style ones on the 400 even if you keep the small early brakes. Just make sure to match them with the proper master cylinder. Early pickups still had drums in the rear. Later stuff and SUV's were disc all around.
Actually it’s sort of the other way around...
99-04 pickups (1500 only, 2500/3500 had 4-wheel disc all of GMT-800) had 4-wheel discs, but for 05-06 switched to rear drums and bigger front discs/calipers. The SUV’s kept the rear discs but improved them.


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