Re: 72 K30 Build
 

I thought the same thing for a minute but we have two K trucks here, one 10 and one 20 that are mounted the same way he has his. The mounting is correct, but I think the problem is K20 engine cross member and c20 frame rails. Not 100% sure but it looks like it is the problem as the frame rails curve down right before the cross member is in the correct location. Brett, you may have to do some trimming in this case.

Good luck,
Thomas

Re: 72 K30 Build
 

Remember, your frame rails are thicker than a normal 1/2 or 3/4 ton. Tighter fit. Trevor

Re: 72 K30 Build
 

Jim, I was wondering the exact same thing also. Found a pretty good pic on the lower part of pg. 148 of the 67-72 AIM. Something else that we noticed is that the pieces are kind of tapered where they come in contact with the rails.

Was hoping that somebody would chime in that knew for sure the correct orientation. Thank you Thomas!

We were thinking the same thing and that's kinda why my thoughts went straight to modifying the piece.

Dang I hate too do that already to such a cherry part. So decided to put this on the back burner and come back to it when I know for sure. We'll move forward with getting the front axle hung. With it in place we should be able to make a decision on which motor crossmember is going to work the best for us. Since it looks like both might need to be modified to fit.

You gotta love poppin rivits!! Now don’t be too jealous of this mighty vise we use. It kinda match’s the wimpy work bench! ;)

Re: 72 K30 Build
 

Man, you need a proper hammer for knocking those rivets off and out. The air type one works wonders! :lol:

Re: 72 K30 Build
 

Dieselwrencher check out picture 3 he has a single jack. I smacked my hand several time before I got smart and held the punch with a pair of vise grips to pound out the rivets.

Re: 72 K30 Build
 

If possible Brett, put some heat on them brackets around the rivet. They will practically fall out with not much effort at all.

Looking forward to the roller ;)

Re: 72 K30 Build
 

Ha Big D, you mean we can’t get it wit deez? Dem flippin nails keep a bend’n! :devil:

Re: 72 K30 Build
 

I’m thinking the use of vise grips to hold the punch is some really good advice. Not that smart around here though but glad to report no busted knuckles this round.

You know I've got an air hammer and some ear plugs but honestly they were popping out pretty easily with what we were using. So we didn’t need to bring the heat but I’m sure that would work really, really well. A couple of good smacks per rivet with my little friend is all it took.

Wish we could have found my very favorite 5 lb. shorty sledge for this round, it’s currently MIA!

Removed some old remnants of the welded on rear bumper brackets. Still need to lose the original rear spring hangers as I’m sure trying to use them would make the truck way to low in the back.

Re: 72 K30 Build
 

I love it when people weld things to their truck frame :lol:

What springs are you using in the rear?

Re: 72 K30 Build
 

Yep me too! Sure seems to have been popular back in the day. :lol:

Todays plan is to use the K3500 spring pack. Don’t really want to use any blocks like the pic below. So for now it looks like the K1, 2 front hangers with the K3500 spring packs (need to remove 2 add a leafs per side). Rear hangers will probably be K3500 also, TBD by ride height with the front end loaded up.


There is quite a bit of difference in most of the rear hangers. Since receiving the shipment of K1, 2 rear hangers from DLTruck1973. I found out that both the K1, 2 and my 72 C30’s rear hangers are all the same. I’ve got 2 sets of these now, oops. The Longhorn frame has some earlier cast style w/grease able pins (cool) that I probably won’t be using. The K3500 rear hanger set is probably the most HD and will yield the most lift.

Re: 72 K30 Build
 

You don't happen to have the greasable shackles do you? Those are unique to '67 and not reproduced.

A lot of the lift in the rear comes from the front hangars in these trucks, they drop the front eye down a solid 2.5" - I would be cautious mixing and matching them, might mess with your driveline angles.

Re: 72 K30 Build
 

On my crew with the cab & chassis frame, the frame is straight from the kick up back. After spending about a week researching and thinking it through, I am using the 73-87 3/4 ton spring hangers. Since I am using the the AAM 11.5 rear I have to relocate my axle perches anyway so gaining an inch in width on how far out the hangers sit won't bother me. (5.5 " out from frame vs 67-72 4x4 4.5" and 73-91 k30) I think your best bet is to use the k30 hangers personally. They will fill the frame rail closer as the 67-72 style only filled half of my modulus portion of frame. JMO. I needed the longest drop hanger I could find to match how much taller my frame is compared to the longhorn style frame rear. The duramax furthest rear hanger is about an inch lower 10" to the 73-87 k20 9". 67-72 furthest rear is 6" drop. The duramax ones can't be used as they are 4" out in front hangers and 5" out on back ones to account for the frame overlapping they do on the new frame rails. Just trying to help as I have been there and weighed all options out.

Re: 72 K30 Build
 

Hey Brett great build. I will be keeping up on your build. I maybe using a 2wd frame as well. If you have a set of rear hangers you want to get ride of let me know.
I am building a k10 lwb '68 with and for my son. Keep up the updates we all appreciate it.

Re: 72 K30 Build
 

No I don’t, but if it had the greaseable shackles then D & L Truck (DLTruck1973) would have them those guys have got everything I swear! :metal:

I agree on what you’re saying about the driveline/pinion angles and think that is pretty good advice. The K3500 rear position rear hangers maybe a must to maintain the angle without a correcting shim. It will be interesting to see were we end up after mocking up the front end.


This is great info Trevor thanks! Below are few more pics for thought on this 67-72 K20 to next gen K30 rear hanger comparisons.

I was surprised how different the Longhorn/CC 133 “ vs. CC 157” frame rails really are from the transmission mount rearward. It becomes very obvious why the CC 157" is the strongest frame in the series.


Thanks First c10 I appreciate your kind words and will keep you in mind, thanks. Building stuff with your kids is the best and "The Hulk" is going to be a beast!

Re: 72 K30 Build
 

Some parts arrived, poly cab mount & front spring bushing kits. New 67-72 K20 springs showed up also. All those stickers you would think those springs came from Chumbawamba not Kansas City! :lol:

Don't want to lose the 1 ton capacity so we will start with these springs and then add a leaf if needed when the truck is done.

Re: 72 K30 Build
 

Good news is I know why the 67-72 K1, 2 engine cross member did not fit as I would have liked. So I tried it in my 72 C30 RV front frame nub. Slide right up to the front mounting holes no problem, so why not the Longhorn was my question??

Bad news is the Longhorn frame we acquired is tweaked a little bit. :thud: Not a big surprise from a 45+ year old truck frame.

Re: 72 K30 Build
 

Looking at this more closely with a tape found the majority of the frame seems to be square. Not so much from the front cab mount area going forward it hooks to the left side.

Left rail was twisted inward right about ½” at the top where the engine crossmember goes, and then it continues kicking out left going forward. Right rail looks perfect but does bend gradually to the left no twist found. You can kind of see it in these comparison pics.

Re: 72 K30 Build
 

You might be able to use a long bar/tube chained to the frame rail and twist it back. Sometimes these frames have pre load in them from being sprung or what have ya, and they will try to go back to their original formed state. And on your pinion angle, that is a easy fix. Cut the original spring perch welds on the diff housing. Set your pinion angle, and re weld.

Re: 72 K30 Build
 

Really kind of surprising at how easily the steel moves. Also found none of our bottle jacks liked to work laying on their side horizontally need to be vertical, must be a gravity thing.

So put a laser down both rails and found both rails hook to the left by around a 1” or so each. Hoped to straighten it ourselves and we have been partially successful these last few days. Got the twist out of the left rail (cross member fits now), also got a little movement on the left front horn back to the right. Not much luck with the right rail and not enough on the left is how it sits now.

Re: 72 K30 Build
 

If you have a strong trailer with good tie down points, I've used them for a temporary frame machine before. It really helps if you have access to some entry way safety poles outside of a shop door. You can block one side and pull from the other.

Re: 72 K30 Build
 

I like it!

Is there any hook in the frame behind the front cross member? I was just looking at one with a bend in it the other day, and after some careful checking the bend was actually way back at the front cab mount.

Re: 72 K30 Build
 

Thanks both are great suggestions, hey congrats on the new house D! :two:

Thanks Jim, yes from the front cab mount to the rear most engine cross member hole it’s about a ¼” out and grows. Front cab mount to the front of the frame horn is currently an 1” all to the left (so ½” each rail).

We got to a point where we couldn’t get any more movement the way we have been straightening it. Problem is the front cross member is tying both rails together we need to remove it and go after each rail independently squaring as we go. Really glad I didn’t cut up the C30 RV frame nub yet, it has been nice to have a straight as an arrow template (kinda measures 0” and ¼” in comparison). Put the laser on the nub for comparison purposes see pics below. Brought the frame down off the lift to remove the front crossmember and see how everything looks getting ready for round 2.

Side note: I have been trying to get it on a frame rack but the shop I wanted to use keeps putting me off so maybe we won’t need them, I hope.

Re: 72 K30 Build
 

So round 2 did not work as hoped, crap! The frame shop put me off another week, crap! Not getting it and my pile o'crap meter is growing at this point, crap! :banghead: Lined up another closer shop and am hopeful next week it'll be straightened by one of them.

Put the K20 trans cross member in place for a look see. Those are factory C30 trans cross member spacers/mounting brackets sitting there. Just a little trimming and they look like they may just work for this cross member, sweet.

Oh, and Misses 7dee2 wants to know when we're going to start putting in the front yard? :waah:

Re: 72 K30 Build
 

When the truck is ready to haul the supplies, duh! :lol:

I am curious what application those C30 cross-member spacers came from? My truck had a manual, so the crossmember was mounted up forward, and it definitely didn't have spacers like that.

Re: 72 K30 Build
 

I'll tell her what you said and hope she doesn't punch me! :lol:

Your GMC would have had them had it been an automatic, they were pulled from my 72 RV frame nub.