I have an '80 2wd crew that I plan on converting to 4wd and swapping in a Cummins and A518. I'm assuming that I need to replace all the front frame cross members, and will the trans/t-case cross member bolt in? What about replacing rivets with bolts? Are there existing holes in the frame rails for everything to attach? Looks like some of the holes I need are there.

 

My plans are for a very similar conversion.

It looks like there are locating holes for the front spring brackets just behind where the bumper bolts on.



This looks like your starting location point for the reverse engineering involved. This should give the correct location for the front crossmember (#1).



Then measure back to the next crossmember from the number 1 crossmember to locate its position. Also note the height of the #2 crossmember above the bottom of the inside bottom of the frame rail. I plan on making a hardwood location spacer to retain the correct position spacing to keep the correct installed height. That's far easier than trying to hold it in place to mark the hole locations.

The next step in my plans will be to use the engine/trans/transfer case assembly as a location jig to get the proper location of the transmission crossmember. This would only apply if you are doing a body off crew cab conversion.


You may also want to note that the rear spring bracket on the front spring is located aproximately one inch higher in the taller 92 & 93 frame than where it was located in previous years.

A few other tips if you want them. Buy at least two each of the following size cobalt drill bits; 1/8", 1/4", 3/8" Take a pointed ***** punch and locate the center of the round humped sides of the rivets. Then drill the rivet head to the required depth to reach the frame using each of the above bits. Do not drill all the way through because you will oval the holes in the frame. Then take a three pound hammer and a sharp chisel and peel the rivet heads off the rivets. Then take a 3/8" pin punch and drive them out.

I plan on mounting the transplanted pieces using Grade 8 high strength hex flange head bolts and stover flanged deformed thread locknuts which are available from Mcmaster.com These do not require any lockwashers or flat washers and make a cleaner job. In other words it will look factory and not like a cobbed job.

 

I noticed those 3 holes behind the bumper holes. Your "reverse engineering" makes sense. Today I looked things over some more and it looks like there may be no other holes to work with except the front 3. PapeCat had some good advice on replacing rivets with bolts, he recommended reaming the hole to the next size up maintaining a good tight interference fit, otherwise there could be enough slop to eventually loosen the cross-member and oblong the holes. When measuring my '93 frame I found that the front section was the same height as the '80 until the "kick-up" behind the seats. I guess the front spring rear attachment should be located in the same exact spot on the '80 like the '93.

 

I guess I need to follow my own good advice, Chris... This afternoon I was on a mission and I dismantled the 92 Ramcharger front xmembers and also removed the ones on the '72 crew... none of the holes were in the right place for the newer style xmember.... I eyeballed it, pilot holed it, and then went straight up to the 1/2" drill bit from there. The reason I didn't go to all the trouble of reaming was basically because I couldn't find the right hardware... the bolts were going to have to be mighty long to have enough grip length to actually have that interference fit.... I think it worked out OK in the end. I just used lock washers but I'm going to keep checking them, would've been better to get a little bit longer bolt and double nut the bolts for the engine xmember....

I can get you in touch with Mike if you like but he did the same as I just did with the grade 8 bolts on his 2x to 4x conversion...

 

Locknuts in 1/2"
http://www.mcmaster.com/#90949a033/=32gpxn

Note: non-reusable.


1/2" Bolts:
http://www.mcmaster.com/#92316a714/=32gsli


I prefer this method over the double nut menagerie.

I order all of my unique hardware from McMaster. This is where I buy my replacement stainless screws for tail lights etc. I can usually place an order and have the part the next day using standard shipping rates.