85 GMC Sierra Classic 1 Ton Crew Cab

[Mattman2010]

If I could even afford a cummins, there wouldn't be any money left over to modify it haha

[Mattman2010]

Well today I got the cab removed, thought it was going to be harder to remove than it was but the tractor made it really easy. I removed the front suspension/engine crossmember and also got the front body mounts removed. I as going to try to get the front body mount/front spring mounts mounted but I found out that it is not a direct bolt on, I am going to have to figure out where to mount them.

cab setting on the ground


moving the frame back into the shop


front suspension removed


the difference between the 2wd core support mounts and the 4wd mounts, you probably cant tell but the bolt holes do not match up

[Mattman2010]

As I have said before I seem to change my plans a lot. For now I am just going to be running a Dana 44 and Corp 14b for axles right now. I want to get this truck up and running and save some money for now so I am going to wait to run duallys on this truck.

Now for the update I started to get the front axle installed. I first pulled a tape on the stock 2wd bracket to see where I needed to get the 4wd bracket mounted. I found out that one hole lined up just where I needed it so I ran a bolt through that hole and drilled new holes for all of the other holes needed. I have the axle bolted to the front brackets I just need to get a 2 inch hole saw so that I can mount the back of the springs.

My k20 engine cross member/engine mounts is not going to work on this frame, I am going to use the stock 2wd engine mounts and box them in and then make a new cross member.

Once I get the front axle fully installed and make sure that the 4x4 steering box fits together with everything and get the engine mounts boxed in I am going finish drilling some holes and welding some stuff then start painting the frame!

2wd mount


4wd mount


Dana 44 half way installed

[Mattman2010]

Well today I kind of have a big update. I finally traded my 454/th400 for the 6.2 diesel/TH400/NP208 today! I have modified my 2wd 1 ton motor mounts to work with the 4x4 as the k20 cross member would not fit. i have boxed them in and I still need to buy some steel to create a cross member!

6.2


th400/np208


the guy I got this stuff from also has a turbo setup for this engine, I might trade him a flat bed for the setup but I wont put it on for a while!

[1985-GMC]

Very nice! That's a major piece you can cross off the list.

[Mattman2010]

Yes it is, I still have to locate the IP valve for the vacuum so that I can run the automatic transmission.

[Mattman2010]

I never did show what I did with the 2wd motor mounts to make them work with the 4x4 stuff. What I did was I took a piece of metal and bolted it to the bottom of the frame. I then welded it to the motor mount and then added some gussets for some support.

Drivers side


Passengers side


I am going to have to trim the bottom of the motor mounts some as I have about 5 inches from hitting the differential and I don't have all of the weight on the truck yet.


I went ahead and bolted the 6.2/th400/np208 all together to get an idea of how to make an engine cross member and to also see what I was going to have to do to mount the th400/np208 to the frame.





This is the stock 2wd tranny cross member, i was thinking of modifying it to work with the np208, but I think I am just going to make a whole new cross member for it, as I have heard that the stock 208 cross members are "W" shaped.


As you can see it is not far enough forward, and the front drive shaft wont mount up with it being that way. So I think the best thing to do will be to make a whole new cross member.

[jltait]

Mattmann,
I think you can use a crossmember from any k20 with the same transmission t-case, however instead of hanging it below the frame rails sandwich it between the flanges of the rails like a car typically is.
JLT

[Mattman2010]

Well I was just throwing around the idea of test fitting a NP205 cross member that came out of my k20 onto there and it looks like it will just need two 3/4 inch spacers for the bolts that mount the transfercase to get it to line up right where i want it!

[1985-GMC]

My K20 np205 cross member is exactly the same as my K5 np208 cross member, but remember that the C30 frame hangs down 2" lower.

[p_rubottom]

Originally Posted by 1985-GMC

My K20 np205 cross member is exactly the same as my K5 np208 cross member, but remember that the C30 frame hangs down 2" lower.

Thank you for this information.... Im at the exact problem with my build, i didnt even think to check this!

Keep up the good work on the build Mattman looking great!

[Mattman2010]

Thanks, p_rubottom your build is looking good as well!

[jltait]

All,
Yes the k30 frame is thicker, but I am sure it uses the same crossmembers. Put the crossmember up inside the frame flanges resting on the lower flange instead of hanging below the lower frame flange like it does on the k10/20. Because of the shape it will kick the crossmember up the same as the frame depth difference. Here is a link to a k30 showing how the crossmember sits. this makes up for the frame depth difference.

http://www.rustfreeclassics.com/imag...olution%5D.jpg

JLT

[Mattman2010]

JLT, I tried to do what you said and stick the cross member inbetween the frame rails. This did not work. It does not set flat on the frame rails.



I could put some kind of spacer to get it to set right, but in the end it would cause my transmission/transfercase to be to high.

I am just going to mount it to the bottom and run some 3/4" spacers between the transfercase mount and the bushings. This will allow me to be right in line with the stock mount for my carrier bearing. I will not be 4x4ing this truck hard at all so having the cross member that low will not effect anything.

[Mattman2010]

These are a few things I need to get done before I go about mounting the body.

• Remove Engine/transmission/trasnfercase
• Weld up some holes that I need to drill new ones through
• weld up brackets that where damaged when removed
• mount rear shocks
• mount front shocks
• rebuild the front axle (ball joints, ujoinst, brakes)
• replaced rear brakes
• Paint chassis and axles
• Get drive shafts shortened/lengthened

For the most part these are the big things I need to finish getting done before I paint the frame. I have forgotten some of the little things, and some things that I am sure I forgot to address. After the chassis is painted and everything is installed I am going to mount the body and drive it like so till I can find a new cab.

[jltait]

Mattman,
Hmmm, I was sure the crossmembers were the same. I have one from k20 and 1 from k30. I will need to take a look again.....Just had a thought...usually all these trucks (at least the k20's have spacers. The crossmember rides below the frame and the bolts go through a spacer that sits on top of the frame rail then through the frame rail and finally through the crossmember. ...maybe put them between the frame and crossmember so the spacers sit on the frame and the crossmember sits up on the spacers. should be 4 spacers, 1 for each bolt.
I will try to repost picture showing where I am thinking to put the spacer. I plan the same type of conversion but with a nv4500/np205 soon, so I have a vested interest in your success.

[Mattman2010]

JLT, that could work, but as I have stated before if I go to high my carrier bearing on the drive shaft will not mount into the stock location. If i where to use the spacers that would wind up making it to high.

The way you have showed the spacers are not where the bolts go into, I understand what you are trying to show me. The spacers are not very long and they need to reach pretty far up. So I think if you used spacers you would have to make new ones.

The blue line shows where the holes are, the red block shows how tall the spacers would need to be.

I hope you can understand what I am saying. I am getting some spacers, but I plan on removing my drive train tomorrow so I can finish up a few things before I paint the frame, so I wont be able to get pictures of how I am going to mount it.

NV4500/205 sounds like a good tranny/transfercase. I am just putting the truck together for now and then rebuilding it later when I can find a new cab. I might try to find a different transmission and run a 205, but for now i am going with the th400/208.

[jltait]

Mattman,
I did a little research that I hope helps you. First 4 pic's are a double hump crossmember that I picked up for my truck when I do the nv4500/np205/4x4 conversion on my R30 ('87 2wd dually). This is from a '85 k30 dually that had an np205/sm465 4 speed, It slides right into the frame and sits nice and flat and appears to have the mounting position correct for the desired driveline angle. Next 4 are a mid 80's single hump, again it sits nice in the frame and appears to have the same mount height for correct driveline angle. Kind of hard to tell though 'cause I had to put it backward to clear the exhaust which is on the driver side on my R30. The last 3 pictures are of the crossmember in my current running (barely) plow truck It has a th700r4 and np208 transfer case and I do not think the tranny/tcase have ever been pulled from this truck. Note the mouting position and that it appears to be Identical to the double hump crossmember in the first series of pictures..

I had another truck previously that had a np205/th400 and it too had the doublehump crossmember. I think GM may have commonised the crossmember design in the mid '80's that may have been more tranny/tcase specific previously. I am thinking if you pick up a Doublehump from a mid 80's truck as shown that it should work for you.

[jltait]

Single Hump Pictures...

[jltait]

k20- th700/np208 doublehump crossmember

[Mattman2010]

JLT, thank you for the pictures!

The Double hump, or as I have heard it called "W" cross member is what I need. I can not find anyone that is willing to sell the cross member out of their 1 ton frame. This is another reason that I have been going with the idea of just using the cross member out of my k20.

It looks like the cross member in your k20 is the same as the one that came out of the k30 its just mounted in side or under the frame.

I wish I could find one of those cross members, but I just have not been able to locate one!

[jltait]

Mattman,
No problem I can feel your pain. Unfortunately the only extra crossmember I have is the single hump. Obviously I still need the one in my K20 and the other is for my conversion project. I will keep my eye peeled for one though, but at least you know a mid 80's K20 double hump should work too.
Jason.

[Mattman2010]

Thanks JLT.

Will a single hump work with a 208? I dont really think that there is a need for the double hump I think the single hump would work.

[jltait]

Mattman,
It sure looked like it would, I think I got it from a K5 Blazer with an np241(same externally as an np208), I had it slid into the frame and it appears everything lines up the same. Because of interference with the exhaust I had to put it backward, but it fits into the rails the same as the doublehump and the mount height appears the same. I think the only issue would be exhaust clearance which you could reroute I suppose. I think these were for trucks with passenger side exhausts.
I need the mount off the one I have otherwise I see no reason that you could not have it for the shipping cost, I have no need for it but have no Idea what shipping to you would cost..I am at zip code 48827 if that helps getting an estimate. I could weight it for you tomorrow.
...Jason

[Mattman2010]

I have to get a new exhaust made for the truck anyway as I am not putting the same drive train back in it.

Sounds like a good deal to me. May I ask why you are taking the mount? And is the mount just a rubber bushing type thing? like this one