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'85 K5 "Denali" Blazer: Front 4-link

The goal is to restore and upgrade this truck for mixed use on/off road (ex: drive across the country to a national park to 4x4 camp).
Thanks for this info. Obviously there's no guarantee a 6L80 would behave the same way, but I assume your 4L80 shifts normally when the transfer case is in low range, despite the transmission not "knowing" it?

I have read that there are separate shift tables, but I don't have my head wrapped around that stuff much yet. I have also read some people say it shifts poorly (shifts at way too high rpm, etc) when it's in low but the TCM doesn't "know", and some people say it's a non issue.

There has to be an output speed sensor for the input to compare to for shift tables. So as a clarification your tcm is going to care about output speed but no it does not have to be behind the transfer case.

It is a very common practice with both 4l60e and 80e transmissions to run them as a simulated 2wd by adding the output speed sensor before the t case somewhere.

4l80es get the benefit of having the factory 2wd case location. However, you have to have the 2wd reluctor wheel installed. 60es I have seen it put into the t case adapter because I believe the factory location is on the tail housing.

I am not well versed in the 6l80/90s so hopefully someone else chimes in. Your plan to have the computer run the tranny and your gauges pull speed from t case output shaft is actually the same way I am currently setting mine up.

My 4l80e was built with the 2wd reluctor wheel and after adding the speed sensor my terminator plugs in there. My current speedometer reading was taken off the 241c but since I added the magnum/205 I had ORD machine the housing to get a correct speed regardless of low range.
 
Thanks for this info. Obviously there's no guarantee a 6L80 would behave the same way, but I assume your 4L80 shifts normally when the transfer case is in low range, despite the transmission not "knowing" it?

I have read that there are separate shift tables, but I don't have my head wrapped around that stuff much yet. I have also read some people say it shifts poorly (shifts at way too high rpm, etc) when it's in low but the TCM doesn't "know", and some people say it's a non issue.
I have not personally had mine running/driving yet but yes from my understanding the transmission doesn't really care.

As to the people that say it works likely have the activation set correctly to bump it into the 4wd shift table AND have the correct values in the table to match the pulse counts the computer is seeing from the output shaft.
 
New set of spindle studs showed up so I got my knuckle/spindle/hub all back together. The tie rod is on to help roll the truck onto the trailer whenever that happens, but I didn't bother with the drag link since the axle will immediately have to come off once the suspension stuff begins.

Hopefully soon...

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Got it over to the high school shop with my brother in law today. Took next week off work to get as much done on the suspension as possible. I also got these giant Sunex jack stands to put the front of the frame on.

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As is tradition, I didn't make quite as much progress as I hoped, but still not a bad day. Axle is out from under the truck, shock mounts and leaf spring perch are cut off and ground smooth (took forever and was not fun LOL), the passenger side axle tube is welded to the center section, and the passenger side link bracket is tacked on. I did have to clearance it slightly to make sure I could get a socket on the upper ball joint castle nut.

Back at it tomorrow morning!

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Spent all day today welding the link brackets to the axle housing. Went ahead and fully welded them because there's really only 1 way they can go, but everything from here forward will only be tacked until I know it's all where I want it at the very end. I also welded the other axle tube, which I don't think I really need to do (especially for my use case) but it seemed like a "why not" type thing while I'm doing all the other stuff.

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I did have a fitment issue with the driver side link bracket. 90% of it fit perfectly, except for one of the plates that makes up the bracket. The plate seemingly is supposed to be attached to the axle tube (parallel with it) but it had a quarter inch gap or so. The bracket pretty much "keys" onto the axle with semi circle cut outs and has to match angle with the passenger side bracket, so there really was no way to get it to sit on there better.

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After quadruple checking the angles and measuring where the links bolt into in the bracket (distance to the axle tube), and confirming things match between driver and passenger side, I decided to go ahead and weld everything I could, and make filler pieces for the areas that didn't fit well so I could weld those too. This unfortunately added a lot of time, but it's done.

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I did call ORD right when they opened, and they took a message for a technician to call me back later, but unfortunately I didn't hear back until close to the end of the day (not blaming them, I am sure they are very busy) and they requested pictures, which I sent. Given that the angles can/do still match and the bolt holes seem to align correctly from side to side, I assume this is just an old-truck, modify-as-needed type thing. Or maybe the bracket needs to have that plate just extend down further, because then it would contact the axle tube. Either way, I don't think it will cause any problems going forward.
 
Spent all day today welding the link brackets to the axle housing. Went ahead and fully welded them because there's really only 1 way they can go, but everything from here forward will only be tacked until I know it's all where I want it at the very end. I also welded the other axle tube, which I don't think I really need to do (especially for my use case) but it seemed like a "why not" type thing while I'm doing all the other stuff.

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I did have a fitment issue with the driver side link bracket. 90% of it fit perfectly, except for one of the plates that makes up the bracket. The plate seemingly is supposed to be attached to the axle tube (parallel with it) but it had a quarter inch gap or so. The bracket pretty much "keys" onto the axle with semi circle cut outs and has to match angle with the passenger side bracket, so there really was no way to get it to sit on there better.

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After quadruple checking the angles and measuring where the links bolt into in the bracket (distance to the axle tube), and confirming things match between driver and passenger side, I decided to go ahead and weld everything I could, and make filler pieces for the areas that didn't fit well so I could weld those too. This unfortunately added a lot of time, but it's done.

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I did call ORD right when they opened, and they took a message for a technician to call me back later, but unfortunately I didn't hear back until close to the end of the day (not blaming them, I am sure they are very busy) and they requested pictures, which I sent. Given that the angles can/do still match and the bolt holes seem to align correctly from side to side, I assume this is just an old-truck, modify-as-needed type thing. Or maybe the bracket needs to have that plate just extend down further, because then it would contact the axle tube. Either way, I don't think it will cause any problems going forward.
I could be wrong but looking at the shape of that plate, it should be slid closer to the axle tube, the curve matches the C on the end.
I don't think it needed to lign up with the end to the other plate like I assumed you did.
Unless that plate had indexing tabs and couldn't slide further
 
I could be wrong but looking at the shape of that plate, it should be slid closer to the axle tube, the curve matches the C on the end.
I don't think it needed to lign up with the end to the other plate like I assumed you did.
Unless that plate had indexing tabs and couldn't slide further
I’m not sure if I’m understanding correctly, but in case this helps:

The bracket comes fully assembled, so short of cutting it apart and putting it back together slightly differently, there was no way to make that plate actually touch the axle tube without very obviously throwing off the fitment of multiple other areas of the bracket. The bracket has partial-circle cutouts in it that go around the axle tube, so there isn’t really any up/down or forward/backward adjustment possible. The only adjustment is rotation around the axle tube (which is supposed to match the passenger side via an angle finder) and sliding left/right along the tube (I butted it up to the inner C as much as possible).

I definitely appreciate any input and I’m sorry if I’m misunderstanding anything! I do agree though that the plate in question does seem like it needs to slide closer to the tube (which would have also made it “key” onto the inner C better), unfortunately there’s just no way to do that short of cutting the bracket apart and welding it back together.
 
I’m not sure if I’m understanding correctly, but in case this helps:

The bracket comes fully assembled, so short of cutting it apart and putting it back together slightly differently, there was no way to make that plate actually touch the axle tube without very obviously throwing off the fitment of multiple other areas of the bracket. The bracket has partial-circle cutouts in it that go around the axle tube, so there isn’t really any up/down or forward/backward adjustment possible. The only adjustment is rotation around the axle tube (which is supposed to match the passenger side via an angle finder) and sliding left/right along the tube (I butted it up to the inner C as much as possible).

I definitely appreciate any input and I’m sorry if I’m misunderstanding anything! I do agree though that the plate in question does seem like it needs to slide closer to the tube (which would have also made it “key” onto the inner C better), unfortunately there’s just no way to do that short of cutting the bracket apart and welding it back together.
I thought they came separate.
They should have
 
Got the shackle brackets and rivets off the frame on both sides, and fit up and installed the last passenger side Deuling plate. Not thrilled with my welds on this, but oh well. Slowly but surely.

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The top/rear weld that isn't done I'm going to do later, since I'm planning/hoping to get the body off the frame at some point and with the body in the way that section is very hard to get to.
 
Today seemed like a lot of work without a lot of progress. I did get the other side Deuling plate on (other than the section I’ll do with the body off). The welding went much better today, I don’t know what I was doing yesterday.

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Also got the transmission crossmember out (probably in the way of the frame brackets) and have a piece of rectangle tube between the frame rails holding the transmission up. Put the axle on a dolly thing the school has and got it under the truck again. Going to try to hold it near ride height and clamp the brackets to the frame in the ballpark of where I think they’ll go, just as a starting point.


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I also heard back from ORD about the axle bracket. It was built wrong and they don’t know how/why. I got the impression they would have replaced it had I not welded it on already, to their credit. They did confirm that doing what I did and filling the gaps is fine and everything will still line up (I took measurements before welding it on, but nice to have them confirm).
 
Didn’t quite get the links done today. More issues with the ORD brackets that cost me a chunk of time. The spacing for the joints is too small by a little over a millimeter on both the axle side and frame side brackets. Had to grind a decent amount to get the joints to fit in the brackets. Also missing hardware in the “link arm hardware” bag (way too few washers and, weirdly, way too many nuts).

I think I have the frame side brackets clamped where they are gonna go (9ish inches behind the body mount). Without cutting the links down, that put the axle about an inch behind where it originally was at ride height. But since it will arc forward as the axle travels up, I think it will work. I can also move the brackets forward if needed. Still going to push the axle up once the top links are in and see where things land.

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Got the links in and brackets tacked to the frame. Ended up moving them forward about an inch from where I had them. They are now 8.25" behind the body mounts, and with the links at the full length as they came from ORD, that puts the axle pretty much exactly in the stock location at ride height.

Feeling pretty happy with how everything is positioned, but I may move stuff once I get the panhard bar in and start cycling things.

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