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5 on 5" rear end swap in my '62 GMC - 10 bolt vs 9" vs Dana 44

13K views 8 replies 3 participants last post by  F&J 
#1 ·
I'm swapping an 89 Suburban front end onto my 62 GMC to get cheaper, easier to find front end parts, power disc brakes, and power steering. Might as well not buy the $$$ aftermarket 6 lug rotors, as I need new wheels anyway. Gt some Torque Thrusts for a smokin' deal... 5 on 5" bolt pattern, same as most 1/2 ton 73-87/91 GM trucks.

My rear end on the GMC's were Dana 44's, where the Chevy's were usually GM 12 bolt. The Dana's in these are REALLY hard to find parts for, and not even sure if anyone makes axles for them anymore... The Dana 44 is a fantastic design of a rear end otherwise. The GM 10 bolt is good enough, but I'm looking for the same width, and most of the 10 bolts are 1.5" wider. These wheels and tires would be a squeeze in the rear with much wider (trimming/rolling the lip if that is enough).

I kept thinking that I'd like to keep a Dana 44, as the no-C-clip design is far better than the GM's C-clips, and the overall design is better. I'm having a hard time finding a Dana that is the right width, or swap info on these. Then I'm faced with the same off the shelf parts problem, as most Jeep Dana's or Mopar units won't have the 5 on 5 bolt pattern I need... Any advice here on what to look for? Most GM trucks that used them were using the front Dana 44 only, GM Corporate rear. GM cars were limited to some hi-po 80's-90's Camaros and Vettes, 5 on 4-3/4", and IRS on the vette.


Now I've been digging around and found that some Ford 9" rears in some trucks, and some 73+ cars have the 5 on 5" bolt pattern that GM uses. Now I'm getting somewhere!


Has anyone had any experience with any rear end retrofitting like this? I need one that's about 60-62" wheel mounting surface width. Disc brakes would be nice.


Still haven't totally ruled out rebuilding my Dana 44 and having custom axles made, but if I ever wanted discs, the drum backing plates are welded to the axles on these! Have to cut them off and weld on the GM brake mounting flange.

Still may look into a newer GM rear from a Jimmy or Blazer, the ones that use the discs that have an E-brake drum inside the rotor hat. Not sure on 5 on 5 pattern for those either, however.
 
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#4 ·
I put many 60-66s together for customers in the last 15 years.

These are just my opinions, so do whatever you want.


Swapping in a 89 entire front suspension crossmember does not get you power steering, nor power assist on the brakes. It does get you discs, coil springs AND rubber a-arm bushings....and a LOT of work.

The stock 60-62 suspension will ride even nicer than the nice riding 63 & newer front suspension. If you want to split hairs, the metal a-arm bushings used from 60 to 70 actually handle better on severe handling, and definately will hold an alignment better than rubber ones. The drawbacks are that those metal bushings sometimes won't take grease if it was not maintained correctly.

Yes, I did do a 61 conversion to coils way back, because repro lower balljoints were not being made then like they are now, and NOS ones were very hard to find. If it were me, I'd keep the torsions and search for a disc brake kit for 60-62.

As I said before, I would just take the simple approach on the rear swap, going with a later c-clip gm truck/suburban rear. Lots of them went 100-200k miles, and yes, some failed before 100k.

On rear discs? It just isn't needed...but I guess you want them to show on the rear, through the TT spokes?


As with any project, you can take the normal path, or go for something real different if you have the time & skills.
 
#5 ·
F&J said:
Swapping in a 89 entire front suspension crossmember does not get you power steering, nor power assist on the brakes. It does get you discs, coil springs AND rubber a-arm bushings....and a LOT of work.

Sorry, you misunderstood my wording I suppose, as my swap does all this. The power steering is still hooked up to all the 73-91 Suburban front end parts that are attached to the crossmember, as well as all the brake lines, prop valve, booster, and MC off of that vehicle sitting in a crate...

Yes, I know, it's a lot of work, but no way in heck am I running a single reservoir brake master cylinder... The 4 wheel drums stopped better than I thought, with less effort, but the brake fade is obvious on hard stops. I liked a lot about the torsion bars, and thought hard about keeping them, retrofitting a newer PS box to it, getting the brackets to use the 72 calipers and rotors, etc... But ultimately, I wanted ease of parts interchange in this truck. If I broke a torsion bar, who knows how long it;d take me to track down another. What if I was on vacation with the GMC? Also, there are millions and millions of 73-87/91 trucks and burbs out there, making the parts as dirt cheap as they get. An entire front end rebuild on the 62 parts is around $1100 (parts only of course). An 89 is in the upper $200 range! The coil springs are very easy to find a quick replacement for, and I can do this with all factory parts from really common 1/2 ton vehicles. Although I kinda wanted to keep the torsion bar setup, these factors (price and accessability of parts) ruled out.

The truck drives like a tractor with the slow steering, and leans really bad in corners with no sway bar. The sway bar came with the 89 front end, all for $130. The price is definitely clear now that this was FAR FAR FAR cheaper...
I really do like the coil spring truck arm rear suspension on this thing now, and I think I will be quite pleased with the end result after the PS/PB retrofit, discs in front, Suburban front sway bar and 3rd gen Camaro rear sway bar, 1/2 ton HD progressive rate TRW rear springs (maybe fronts, too), Tremec 5 speed, Firestone Indy 500 tires (great road huggers), Holley Carb, HEI, and indexing some fancy spark plugs. I really hope I can drive like a granny and get 17 mpg hwy out of it. The road handling should be fantastic at that point, as my 89 Suburban handles pretty fantastic with the tall truck tires, only front sway bar, longer wheelbase, taller, etc... One day I may swap the TBI from that onto the GMC V6 to try and retain it and get almost respectable mileage. We'll see how the HEI upgrade does. Right now, the GMC isn't as sporty to drive as the limo-length 89 Suburban, but after these upgrades (and clutch MC retrofit from an '85 C20), I think the 1962 GMC will be a fantastic ride. The thought of breaking down somewhere with my main vehicle (89 body is ready to rust off the frame), and not being able to get parts for 4 days, that weighed heavily in my mind. I can carry some spare GMC V6 parts with me, but an entire truck's worth of spare parts, no...

F&J said:
The stock 60-62 suspension will ride even nicer than the nice riding 63 & newer front suspension. If you want to split hairs, the metal a-arm bushings used from 60 to 70 actually handle better on severe handling, and definately will hold an alignment better than rubber ones.
As I said before, I would just take the simple approach on the rear swap, going with a later c-clip gm truck/suburban rear. Lots of them went 100-200k miles, and yes, some failed before 100k.
On rear discs? It just isn't needed...but I guess you want them to show on the rear, through the TT spokes?
I have Global West Del-A-Lum solid aluminum/derlin A-arm bushings for my 71 Camaro. Now that you mention it, I may just have to look into some for my GMC's 89 front end also. There are a lot of benefits to running them. No deflection, smoother operation being the main ones. I didn't realize the old trucks had solid bushings. They will take some of the cushion out of the ride, but they allow the springs to do their work better, as they are smoother. I was already thinking of a PST polygraphite front end kit for it actually, but now I'll probably look into the solid route.

I have probably given up on the Dana 44 route unless I can get parts for my current unit to swap to posi and 5 lug, and get rebuild parts for it... Ford used the 5 on 5 lug pattern from 73 and on (until 80-ish?) on some 1/2 tons and also big passenger cars (and Lincoln's). I am still looking into a Ford 9" that would use the 5 lug on 5" and have a 60-62" width (might be a wild goose chase). I'd rather have a Dana than a major competitor to GM, but you can't argue the durability of a good 9" rear.

And yes, I know the rear drums are adequate, but you're right, the discs would definitely look "show-ey" behind the revealing Torque Thrust D 5 spoke wheels... I need to scavenge the boneyards to do some field research on the newer Blazer/Jimmy/etc rear discs with the drum e-brake inside the rotor hat. If I don't keep using my Dana 44, I'll probably eventually swap to those brakes.

The 10 bolt rear and $130 weld on brackets would by far be cheaper, and there's nothing wrong with a 10 bolt, but the Dana is just so much nicer (except for the GMC version's parts availability). I'm most likely going to go the 10 bolt route, or else pull my axles, check the condition of everything, and see about just getting the axles and drums redrilled for 5 on 5. If I can get new parts and posi for mine, then I'll do it and live with drums just fine. If I get real bored in a few years, I could always weld on GM backing plate mounts in place of the permanent drum backing plates on the Dana. I'm not sure how available the GMC's rear drums are, or where to even find the parts lookup for them... Most stores' think my 62 GMC has the Corporate 12 bolt brakes, among other parts, and gives me the wrong stuff!
 
#6 ·
Sorry, you misunderstood my wording I suppose, as my swap does all this.
No, I didn't :D The P/S box attaches to the 62 framerail; so either way, you need to remount the P/S box. You can use a REZ kit, or homebrew it with black pipe sleeves welded into drilled holes in the boxed 60-62 frame.

If you do a x-member swap, you need to deal with the idler arm situation. Some report using the late idler, I have not tried it. If I do a x member swap, I use a mid 60s 3/4 ton centerlink & idler, so it all bolts together correctly and it will now have all large taper holes for the late tierods. I am not even sure that you can use the later centerlink, I thought it was all wrong??? as far as measurements? Let us know what you end up using.

On the P/B; What clutch linkage are you planning?? The stock 60-62 stick was a dual master for hyd clutch and other side for single circuit brakes. I have done a swap to P/B and was able to keep the hyd clutch. It required a new single master for the clutch, and then a booster added along side for the 67+ dual master. Tight fit, not pretty, but works well. That truck lives in NYC traffic :D


... But ultimately, I wanted ease of parts interchange in this truck. If I broke a torsion bar, who knows how long it;d take me to track down another. What if I was on vacation with the GMC?
That's the line I hear when guys trailer their rods with brand new GM crate motors to the Nats :rolleyes: No faith in their work or just a bunch of Nancys :D Yes, I am sure you have your mind made up, but other people read these posts in the future for input. ;) I really take note of what the older guys report about these trucks; guys who drove them back then, new and used.

One customer drove his 65 GMC sub to Fla & back to Long Island NY a couple of years ago. I had swapped in a th400 to his 305 GMC v6 (rarest parts on the planet needed to do it). p/s,p/b.dual circuit, sway, etc. No problems.

The last 60 chev torsion I did, we only needed 2 lower ball joints(repros were $99 each then, probably lower now), front shocks were just replaced, and the rest was fine. I put on the later P/S without a Rez kit. I put the P/B on w/ dual circuit brake master. And added a 67-72 gm pickup/sub swaybar & hardware. A few holes drilled, that simple. A 3/4 ton has a beefy bar!

I tell all my customers the same: "just adding p/s, p/b & a swaybar will change the entire truck".


Are you using the big v6? That motor is tough on gas, no matter what. Add lots of OD, that motor is a lugger, not a revver. ;) I think it will still be thirsty :(


All in all, these are great trucks with some limitations: a little heavy, not aerodynamic, prone to rot, a little cramped in the pickup cab. I prefer my sub over the pickup, but the sub is not set up for mega towing like my truck is.
 
#7 ·
I know, I was aware that I needed to do a little fab work to mount the PS box. What's one more project, right? Luckily I was able to get all the GMC V6 PS pump bracketry and pulleys from a 60-66 GMC Discussion Group member.

And yes, I know the GMC 305 V6 is a gas hog... I'm hoping that the HEI swap will wake it up as much or more than the Holley 500cfm swap did. The things have a HUGE bore and not so efficient combustion chambers either. Newer GM engines have gone to more the 305 V8 setup than the 305 V6 strategy... longer stroke, smaller bore nowadays. the 305 V6 was designed to have a very short stroke intending to minimize wear (piston speed and travel distance), which it did well (they last 200K and sometimes 300K supposedly), but in turn, they didn't realize how inefficient of combustion that combination would produce... Also, newer engines deal with the wear issue by using more modern alloys ( the 010 020 nickel/tin blocks) and better, more advanced parts... I'm hoping some fancy split fire type plugs, indexing the plugs, and HEI will have some positive impact on the inefficient combustion of these mills.
Also, as far as being a lugger rather than a revver, some of the GMC group guys toss around some custom camshaft grind specs that will wake up the engine a bit and give it more rpm range. Still a fairly mild cam, but I'm wondering if that would help it push the OD any better at highway speed wind resistance levels? The engine was intended originally to be more of a stump puller and hauler than a revver. 3800 rpm is peak hp! With HEI and Holley swap, the GMC guys say theirs will pull good until about 5000 rpm, which is a huge improvement over the points ignition and the Stromberg 350cfm 2bbl or the Rochester 1bbl.

I have been looking for a 60-66 panel or burb for several years now, and all along planned on a 5 speed swap and a small block chevy V8. I liked the GMC's over chevy's because of the dual headlights all years, and the robust looking grille. Then I come to find out how unique the big V6's were, and how they are quite a conversation piece with a small, devout following. Even though I am upgrading most of the rest of the mechanicals, I thought I owed it to the GMC guys and the truck to keep the original engine in it, since it's so unique and still in good shape. I'd love to have a vortec headed 327 or 350 in it with a mild cam, maybe aluminum E-Tec (Edelbrock's vortec style) heads and aluminum intake to save weight. Parts are a dime a dozen and available everywhere. The 305 V6 was rock solid, however. Heck, I'd almost put a 305 V8 in it nowadays with the gas prices the way they are. Drop 200 lbs of extra engine, and gain some efficiency from the design of the engine at the same time! My 89 burb 350 TBI (efficient but not so powerful swirl port heads) will get a nice 21 mpg if I really baby it on the highway. Actually the time I calculated the 21 mpg was with 7 people in it on state routes (with stops here and there). in a 5200 lb truck (gas and driver weight, plus additional weight of the the 6 passengers = 6200lbs). The '62 with the 200 lb heavier engine is only supposedly 4100 lbs. The aerodynamics probably take away from the advantage of lighter weight!

back on topic, everyone just says that the whole crossmember just bolts right in with redrilling a couple of holes, usually just the two idler arm holes. I not only drive an 89 Suburban daily, but got the junkyard parts off of another 89 Suburban. I can check frame widths and all that to see how this swap will work. I'll store your notes on the center link just in case! The crossmember will unfortunately be sitting with the 5 speed tranny for some time in the garage, until I get some major house remodeling long underway, to get closer to owning just one house again, or at least rent the spare and live in the remodeled house! Most of my time the rest of the year will be completely remodeling an 1890 victorian 3 story house we bought (by myself), and building a 3 car garage there. The truck is new to me as of late may, so I'm just getting lots of ideas for the moment, and whatever parts I can find a good deal on. I've almost gotten it in good driving condition after fixing a million small problems. clutch adj, e-brake adjust and brake checkout, add seat belts, and door lock/door latch repairs, and make my gauges and instrument lamps work, and then I'm good! Oh yeah, HEI swap... Then I can drive it occasionally and work out more bugs, and drool over the wheels, tranny, and front end that I have awaiting it for the winter projects!

Thanks again for all your insight, I appreciate it. Just know that I thought long and hard about keeping the torsion bars or swapping. Ultimately, I decided that the good used front end from the 89 was a far cheaper way to go, and the cost of rebuilds down the road would be another benefit. I'm saving most all of the original parts off of this truck as long as I can stand to store unused stuff...

Thanks again for the advice and stories. Now if I could only get some solid answers on if, who, and where in regards to parts for the GMC Dana 44!
 
#8 ·
clutch

I think I mentioned using a 1985 C20 truck's clutch master cylinder with remote reservoir. I was hoping to be able to ditch the across-the-steering-column clutch pedal linkage, and just use the same leverage pivot point and go straight through the firewall with the clutch MC rod, but I have not 100% confirmed this as that would mean removing the stock clutch/brake MC to dry fit. The bores are off by 1/16" between the original slave and the C20 slave, so I may end up having to fab up a bracket to bolt in the newer slave, and make mods to the slave cylinder rod as necessary. I may try it with the mismatched slave and mc, but I'm not up on hydraulics to know if that would even work.
The 85 slave bolts in one direction, and the 62 slave has the bolts going 90 degrees from the 1985 setup. I think the 85 bolts go parallel to the slave, and the 62 are perpendicular.
 
#9 ·
You'll laugh, but the one 60-66 that I modded, that I hated to give back to the owner, was a 66 c-10 2wd long step with my usual mods like p/s, p/b, front sway from 3/4ton, AND a 700r4 bolted to the orig 250 straight six :D


That was, by far, the best driver I have done IMO. It was just so perfect around town and on the secondary roads. My tiny complaint was that with the stock 3.73 axle and OD with lockup, it just needed a little better gear like a 4.11 if you hit a big hill on the interstate highway and did not gain speed before hitting it. Other that that, I wish I owned it.

Sad to say it later came back for a mega built sbc with those abrasive sounding Flowmasters. It ruined the truck IMO, and the owner later sold it because he hated it also. His Bro-in-law talked him into the hot motor :pain: Last i knew, he was looking for a stock 6-stick shortbed ;)
 
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