FULL DISCLOSURE: Total amateur here, but I do have adult supervision... lol Looking forward to our second season back on the road after a 30 year nap, planning to swap out the original rear end for something a little more highway friendly, from a 69 Firebird. Of course, this means we'll also have to swap out the enclosed drive shaft, and maybe the original tranny as well. Just wondering how others have handled this... Is there a particular open drive shaft that will work or will we have to have one made? And will swapping in the Firebird rear end also require a new tranny or will the original 3 on the tree still work? Any advice/suggestions y'all might be able to offer would be greatly appreciated...
my truck used a 60s Saginaw 3 spd full sync unit hooked up to the original linkage easily the driveshaft was some measuring and junk yard shopping
you may consider installing an S10 5 spd lots of info out there on how to do that there is also a Saginaw 3sp overdrive
Better measure the width of the FB rear to make sure it is not too wide. I used a 70's Chevelle wagon rear which fit just right.
If you are going to go with a open drive rear end, you will need to swap out the stock transmission with a open driveline unit. Dave
On closed drive models, the leaf spring bolt that also aligns the rear end spring pads is either 1" or 2" (cannot remember) off center to the rear wheel openings. You'll need to drill an off center hole in each spring pad on the new rear axle to compensate. If not, your rear wheels will set forward in the wheel opening.
yes the stock 3 on the tree for the 60s Saginaw box also look at 55-63 gm car rears a friend used a 55 in his truck
Thanks for all the info, guys! Much appreciated. Looking forward to takin' 'er down the road with the new fixes...
I believe it's Langdon's that offers 3.55 NEW gears for your year truck now. Unless you really want to tear everything apart and reassemble it with new, used parts. Most rearends, except some trucks, will have 5 bolt hubs as opposed to your 6 bolt hubs still on the front of your truck. By only swapping gears, it'll save you time, effort, and money. I am Butch/56sedandelivery.
Thanks Butch! We actually already have 5 bolts up front with a disc brake kit, and with the same in the rear I'll be able to snag the other two free rally wheels that another friend has waiting for me...
the fire bird rear should be the same as the Camaro and nova which work well with an ad truck. if your trans is good and somebody has a junk later model the tailshaft housings will interchange. butch has probably the best and most economical idea in the long run JMO Tom
I am almost always a more gears equals more better kind of guy. With a 3.55:1 gear, and a tire about the stock height, you might be just over the line for a manual transmission with an overdrive, unless it is the low-ratio S10 T5 (4.03:1 first, 0.89:1 fifth). That might actually work pretty well, if you don't mind a floor shifter. You can get an ultra-short throw base, so the long stick does not feel like rowing a boat. CoreShifters is who I like: http://core-shifters.com/collection...-gm-t5-5-speed-trans-swap?variant=10551810179 You would need to make a tail-mount, but that is a low hurdle. The S10 input shaft is a little longer that the common length for other GM transmissions. It would need to be trimmed, or you'd need a spacer. The spacer, for the easy road: http://www.hotrodworks.com/product/t5-muncie-pattern-transmission-adapter-5-18-bore/ Oh, and my Mom lives in West Haven. I grew up in CT. Still have family there. My brother is in the CSRA. http://www.csra.org/ And runs the 100%Kulture shows.
As has been mentioned, one extremely important thing to note when swapping the rear axle on one of these is the position of the spring pin. On a modern vehicle, the bolt that holds the leaf pack together also locates the axle on the leaf spring. It traditionally as a round head, that fits into a round hole in the leaf spring perch on the axle. On a modern vehicle, that hole is dead-center in that perch. Like so: If you examine how your original rear axle is attached, you will note that it is not affixed by u-bolts, but has a pivoting mechanism. There is a leaf spring pack bolt in there, but it locates the pivoting mechanism, not the axle, per-se. If you put a conventional leaf spring perch on top of that bolt, the whole axle will be about 1-1/2" forward of where it should be. The way around this is to either re-drill a new hole in a fresh perch, or to buy perches designed to correct this: Note the forward hole (in addition to a centered one). There are handy kits for this, in-case you don't want to fab, or in-case you need inspiration: https://www.performanceonline.com/1947-55-chevy-gmc-3100-rear-end-conversion-kit
Definitely with ya there. Can't tell you how many times I went looking for the nonexistent 4th gear while driving this thing last summer... Small world, huh? I grew up here as well, in Bethel. Thanks for all the info, links and photos. Great stuff!
I have a '49 3100 as well. It's an older restoration that I can see had been drag raced and they attempted to patch it up for a quick sale with a new rear end and transmission. I've sorted through a bunch of problems so far and the biggest one was the rear end. They had put a "gm" 12 bolt rear/3:73 in with whatever drive shaft was there already without cutting it, which caused a bad fit. The rear axle was installed at an angle causing the truck to appear lower at the left side when viewed from the rear and the right hand tire was rubbing and actually burning through the side of the truck bed. We took it all apart and redid it and it's good now. Moral of the story, measure 3x install once and good luck with the truck, great year.
Thanks and welcome to the HAMB! Always nice to run into another '49er! Holy cow, that truck must have looked pretty crazy goin' down the road before you set it straight. We will absolutely make sure everything is right before final install. In fact, I might just drive my mechanic crazy with the measuring... ;-)
Somebody did a really nice job with it. I'm in love with it, the next one I build though and I'm going to take my sweet time. I see you're in CT, I'm on the NJ shore. Bookmarked your blog
I put a 69 Camaro axle under my 48 in the mid 70's and it fit well. Gears were wrong for the M21 Muncie four speed it had at the time though. Truck would cruise at 80 at 3000 rpm with N50 14 tires on it. The only problem you might have is that with some wheel and tire combos the tires can get too close to the bed sides. I think I have a 74 Nova rear axle under the truck now and while my regular rear tires clear by a half inch I can't put a standard offset 15 inch rim on the back even with the 75 series tire on it without rubbing. I run a full syncro Saginaw 3 speed now and have for years and they work well. As far as drive shaft goes it's either do a lot of junk yard hunting or have one made.