My 89-91 grille conversion thread

[redz 1970 K5]

Started the tear down last night. Went pretty smooth. I will update this thread as I continue to complete the project; I am anticipating completion on Friday or Saturday right now barring any unforseen circumstances (my middle name).

Step 1- Prepare for the pain

• Remove 4 screws holding the headlight buckets and remove buckets.

• Remove 4 upper and 2 lower grille mounting screws, remove grille. You will need to disconnect the parking light bulbs if so equipped.

Step 2-Pull da bumper.

• Remove the bumper bolts and remove the front bumper; don't forget to mark the relationship between the bumper brackets and the bumper so you can realign the bumper easily upon install. I plan to remove the front bumper push bars upon reinstall. I figure at my height, I am not going to be able to push anything and I don't care for them really.

• Remove the 5 fasteners securing the upper bumper valance to the radiator support and fenders. Remove the valance.

Step 3-We don't need no steenking oil cooler

• This is where you will remove any auxiliary coolers and get them out of the way; in my case I dropped the oil cooler and zip tied it to a tow hook for safe keeping. The junction into the oil cooler is oily, so I can repair that while this is easily accessible. In most cases, you will need to transfer any aftermarket cooler mounts to the new rad support. I will have to do this.

Step 4-Gutsa come out

• Before you start working around the fan, do yourself a favor and disconnect the negative battery terminal.

• Disconnect the upper/lower fan shroud pieces with the side fasteners

• Remove the upper fan shroud after removing it's fasteners from radiator mounts

• I could tell the fan was going to be a PITA, so I just removed the four nuts and pulled the fan; The clearance will come in handy.

• With the fan out of the way, remove the 2 fasteners securing the lower fan shroud to the core support and easily lift the piece out

Step 5-You don't need this stuff

• I have SEEN the radiator left in the truck for a previous conversion, but based on what I saw and previous guidance, it does need to come out; There is really no way to get any clearance on the A/C condenser to begin with, it's worse with the radiator hooked up. I pulled the tranny cooling lines, drained the coolant, unbolted the upper radiator mounts and pulled the radiator.

• Disconnect and remove the battery

• Remove the battery mounting tray; This will be important to reach the core support bolts on the RH side.

DISCLAIMER
Sorry, this next sequence won't have pictures; I left the flash card of my camera at work and couldn't take the time to run back and pick it up!

Step 6-Dissimilate

• Remove the charcoal canister bracket (if so equipped)

• Remove the front axle 4x4 breather tube (if so equipped)

• Carefully disconnect the headlight plugs, turn signal plugs and disconnect all grounds to the core support. Pull the RH wiring through the front of the core support. Carefully disconnect all wiring clips on the way- you will reuse them. Disconnect the horn plugs, and then feed the whole assembly through the LH side of the support. Disconnect any LH grounds and plugs, and then the wiring should now be clear of the support.

• Disconnect the hood release cable from the latch assembly; This is easy enough; once disconnected, pull the cable through the core support and get it out of the way.

Step 7-Unbolt it!

• Almost ready to pull! Remove 2 core support body mount bolts.

• Remove 3 LH and 3 RH inner fender front bolts where the inner fender bolts to the support.

• Remove the 5! RH and 5! LH fender to core support bolts. I say 5! because there are 4 bolts on the inside of the engine compartment, and one hiding behind the upper headlight in front of the core support. I didn't find this until I tried to pull.

Step 8-Fun awaits you

• Time to pull! I did put a 4x4 piece of wood between the fender and tire in the fender well in case the fenders wanted to sag when I pulled the support; I am not sure if it would have sagged or not, but it was probably a good idea to have a fender support there.

• I lifted the support slightly, and then pulled the bottom out. Once the bottom of the support was clear of the body mounts, I pulled the body mounts and then slid the core support out with the bottom coming out first. EDIT NOTE--- MARK THE RELATIONSHIP OF THE BODY MOUNTS TO THE FRAME BEFORE YOU PULL THEM. Just draw a line to align the upper and lower body mounts to the frame.

Step 9-Out with old, in with new

• NOTE- This is a friendly word of advice; All of your belts are very easily accessible; This is a VERY good time to change any fan/accy belts!

• Now there is just a big gaping hole. Time to slide the new core support in, much the same way that the old core support came out. The top of the support goes in first at about a 30 degree angle, and just carefully follow it up with the bottom. I could have REALLY used a second set of hands here. It was pretty hard on my own.

• Once the support is close to position, you will need to pry on the bottom and/or lift as high as possible to get the body mounts back in. Don't forget to get the body mounts back in how they came out... I made the mistake of not aligning the body mounts back up, and as a result getting the fender holes lined up was a royal pain.

Step 10-Bolt it!

• Go ahead and run the body mount bolts through the core support, the body mount, frame, lower body mount and then just loosely thread the nuts on the bottom.

• The fender threaded holes should all be pretty close to lining up with the core support holes. Go ahead and get about 5 threads started on each fender bolt on both sides. Once all are started, just tighten the bolts down in sequence on one side and then the other. Don't forget the fender bolt on the front of the core support!

• Once all of the fender bolts are snug, go ahead and torque down the body mount bolts to spec

• Screw the inner fenders into the new core support with the 3 fasteners on each side.

Step 11-Wiring

• Time for wiring; I found it very easy to splice in the last 6-10" of stock 89-91 light harnesses to the stock wiring harness. This is what separates a well done project to a done project; A WELL DONE splice doesn't mean twisting wire and slapping duck tape over it. A WELL DONE splice is a soldered connection with heat shrink tubing and then electrical tape if necessary! Don't skimp on this. This will prevent phantom electrical problems as well as keeping your truck's next owner from cursing you out.

This is my very crude wiring diagram done on Open Office in about 5 minutes for the headlights; however the wiring is quite simple.


An 'S' Indicates a SPLICE
A 'T' Indicates a termination; there is not a third wire on the 89-91 plug for the green wire. Terminate the wire.

• There are splices required for the front parking/turn signal lights; I cannot remember the colors and will update with a picture when I take a look.

• Just reroute the factory wiring harness along the new core support; The horn connectors are the same so the horn plugs will plug right in; There is also no splicing required for the side lights.

Step 12-Make it work

• Screw in the headlights if necessary; I purposely leave the turn/parking assemblies unscrewed because it's hard to reach the grille mounting screws with them in place.

• This is now where the difference in years will take place, but this is my experience with my 88 Suburban; The 91 core support had no provisions for mounting the evap canister. I had to drill 2 holes in the core support, and used bolts to mount the evap canister to the new support. It was pretty painless with no clearance problems.

• The new core support has NO provisions for the cold air inlet tube for the intake; I am not sure what I will do for this yet. The truck will run without it, and I have months before I am dealing with hot summer air so I will cross that bridge when I get there.

• Route the hood release cable through the new support and reconnect to the new or old latch assembly. Both are similar, but I went ahead and reconnected my old latch assembly to the new support.

Step 13- Final Assembly

• Put everything back together; reinstall A/C condensor, radiator, fan, fan shrouds, battery tray. Reinstall any coolers that mount to the front of the support. Top off coolant.

• Install the new metal upper bumper valance; This has to be an 89-91 piece as well. I was not aware of this; The new headlight buckets screw straight into this piece, so it's mandatory. Your pre 89 valance doesn't have provisions for this setup.

• Install the grille; It mounts to the core support up top, with three mounts on the bottom.

• Reinstall the parking/turn signal assemblies

• Install the LH/RH headlight buckets

Step 14- Final Alignments

• Carefully lower the hood on the new latch assembly; I found that I had to adjust both the height and location of my hood latch assembly to line up with the hood; These are adjustable by the four bolts on the latch assembly. Once aligned, shut the hood and make sure the hood release still works.

• Tune the LH/RH hood adjusters on the top of the core support so when you close the hood you get a nice even gap across the front of the hood.

• Reinstall the bumper.

• Time for a beer! You are done!

[redz 1970 K5]

QUESTION??? FOR ANY CONVERSION GUYS- SHOULD I SUPPORT THE FENDERS IN ANY WAY WHEN I REMOVE THE CORE SUPPORT FROM THE FENDERS? I don't know how much of a load is on the front body mounts and I don't want to tweak anything when I pull the core support. Help would be appreciated!

[pcmcobra]

redz,
I am watching this thread...I am planning on doing mine soon, as soon as I can get the support blasted and coated/painted...
looking good so far.

[edman87]

I am doing the swap also, but swapping the entire front cap. It is actually easier than removing each individual part. Of course, I am in the middle of the buildup and was removing the front cap any way for other purposes.

[aort]

The core support holds quite a load from the fenders. There are more bolts holding it to the rad support than anywhere else. You should brace the fenders somehow before taking it out.

[redz 1970 K5]

Updated original thread; I am pretty far along, but am trying to document thoroughly so I will update more later. The new support is in, my wiring is totally done ( and working), but I have discovered that I am going to have to make a few mods to the support to work for me.

[pcmcobra]

no pics, arggghh

[84 400]

very cool swap!!! i thought of it too at first but have3 since decided i want to keep my 84 looking 1984. but this may come in handy since i want to clean my support. cool thread

[poolboy65-ls1]

See some pics on how you wired the lights up. Maybe a color diagram on what wires to splice to what. Thanks, Mike

[redz 1970 K5]

Here is the conversion done pics... I will finish the write up soon; I didn't get many pictures for the simple fact that I was on a tight timeline and I was doing it alone. I think I learned some things that will help and/or prepare anyone else considering it. It wasn't the hardest thing I have done, and it wasn't the easiest either. Doing it completely myself from start to finish, I was about 10 hours into it.

I need a grille emblem; I know LMC truck has them, so I will order it and get it installed. If you have an 89-91 emblem and don't need it, please PM me!

Anyways, here it is!





Rinsed it off real quick and snapped a shot-



My next project to be installed soon-

[redz 1970 K5]

Before shot for comparison. I am exhausted...

[Jonboy]

Your conversion looks pretty good. If you don't want to unhook the A/C and radiator, it can be done, but the support has to be rolled in place. It is a lot easier to do with the body mounts out of the way. Also, depending on the year of the truck and the wiring on the radiator support (and options of your truck) the wiring needs to be modified a bit. I put a '91 support on a '86 truck, and had to do a little wiring trickery. The '86 truck had 4 lights, so the headlamp wing swapped color for color. The plug at the firewall was a different shape, so it had to be swapped out, and there is tan wire that goes to a pressure switch by the steering box the later wiring harness did not have. Not a major deal, but it did take a little time. Looks like you are getting your truck where you want it. Good job!

[pcmcobra]

redz,
looks great. I have yet to get my front end...my brother has not made it this way yet...
When you do the ignition, we need pics!

[redz 1970 K5]

Stupid LMC truck... I was about to order the replacement grille emblem from them. It was $32.95, I was ok with that. Then I go to checkout and they try to charge $10.95 for a flat shipping/handling rate!!!

$10.95 shipping/handling for a part that weighs maybe 3 ounces and can ship in a very small box or padded envelope. That is ridiculous to have flat shipping rates based on price and not size or weight! I will take my money elsewhere.

EDIT: I found the NOS part from GMpartsdirect for $22 shipped! That's better!

[Russell]

Looks really good! Big improvement for sure

[poolboy65-ls1]

My 81 has 4 lights. I have all the parts but the grill and headlight doors. I should be getting them soon. I'm probably be doing the swap this weekend with or without the grill. I'm ready to get it done.

[poolboy65-ls1]

Any updates?

[redz 1970 K5]

I added a bunch of updates for you. I hope they help, and I will add some more shortly.

[poolboy65-ls1]

Thanks!

[poolboy65-ls1]

Doing my swap today! will post some pics when I'm done!!!

[75shortysocal]

wow nice breakdown, i was thinking of changing the front of my 75....but i figured i didnt want to change what it is, i want people to be able to know my truck is older.....

[panelguy]

Has anyone done this swap on the 73-80 trucks?? I need some info on the hood hinges and cutting of the firewall.

[84 400]

I think to do it on a 73 to 80 you have got a lot of work ahead of you. For one thing the hood and fenders are diffrent on a 73 to 80. you would need tpo convert to the 81 to 87 style hood and fenders and then fallow the above 87 to 91 suberban / K5 swap. It can be done of course but i think i would try to retain the older 73 to 80 front end as they are less comen.

[redz 1970 K5]

I think it could be argued that since the 89-91 front grille only had a 3 year run, and only on Subs, K5s and 1 ton trucks that it is more rare then the 73-80 years. You figure a 3 year run on part of their truck lineup vs. a 7 year run on their full truck lineup. That said, I think the 73-80 is pretty cool looking.

panelguy, here is a great 73-80 conversion writeup from Neil... Not sure if CK5 allows their tech articles to be seen without membership, so I also linked to it from a second location.

http://coloradok5.com/grilleswap.shtml

http://www.off-road.com/chevy/tech/grill/

[poolboy65-ls1]

Got her done!!! This thread helped alot! Thanks! Here are some pictures.