Hi everyone, I recently purchased 49 5 window that I'm currently adding 3" blocks in rear and new 3" lowering springs upfront. Previous owner installed P/S which saves me some time. I have disk brake conversion kit for front but saving it until I get new wheels n rubber. I installed a power brake booster and master cylinder under the cab. The front springs are yet to arrive and I have some questions for the board. Will I need to change the shackles when upgrading to the newer springs? I've never seen a shackle with a bearing that's riveted to the frame, lol.. And after cutting the saddle from rear axle and flipping them and setting the axle on top of the 3" blocks it's apparent that the axle center line is no longer center in the wheel opening, can I flip the springs? It looks like I can't because the front has a bolt and the back has some weird tapered pin shackle assembly much like the front. Your help is greatly appreciated Thanks, Brian
The rear axles aren't centered on these trucks to begin with. Most people move them back 1" to 1-1/2" to center them in the wheel openings.
Yes the rear axle was set up from the factory forward of center. If you are staying with the stock drivetrain, make sure you read up on what you can and can't do with the closed driveline (torque tube). No need to change the shackles unless something wrong with them. The shackle/hanger pins are machined with provisions for a grease zerk. Lots of times these truck were run into the ground and the shackle/hanger pins start eating away at the spring eye bushing. So definitely look into that... Good luck to ya!
Thanks for the replies, great feedback and I'm sure I'll have more questions I've owned many rides but this is the oldest so I'm learning as I go. I used a plumb bob and ran it from in between the rivets on the fender brace which looks to be centered in wheel opening and used a square from center of axle and it measures out that the axle is 3" forward. I think I'll try using 3/8" thick steel plate and cut 2 pieces 2.5" wide x 6-8" long and drill 4 clearance holes 1.25" apart for the center pins on lowering blocks so i can adjust to center the axle. The lower brackets should be the easiest to locate and drill one clearance hole for the center bolt on the leaf spring x2. Thanks!
Yeah, these trucks look much better wit the wheels centered in their rear fenders. Made custom lowering blocks for the rear of mine to move the axle about 1.5 inches. Waiting on Sid to drop my front axle next.
3" forward sounds like a lot; were the rear wheels on the ground when you took this measurement?,they should be.... 1 & 1/2 " sounds like what most are off. double-check before you do the work.
Here's before and after photos from lowering the suspension. I flipped the rear springs (front to rear) and added 3" blocks, I love the new stance I also added brake booster and master cylinder under cab, just need to figure out a good way to add fluid, lol...
I forgot to mention that I machined 2, 8" plates 2.5" wide. And I machined 3 .625" holes for the axle pins and I machined pins to insert into the base of the 3" blocks. I moved the axle 3" back and it still wasn't centered in the wheel well and I didn't feel confident that with using the 8" plates that it would be safe. So that's when I decided to flip the springs and it centered perfectly in the center of wheel well. However when I lowered the truck the springs settled and it seemed to shift 1" back from center, but it isn't that noticeable. Just waiting on Classic in California to get my order correct with the 3" front springs from Posie, then I can jounce the suspension and see where it actually settles. If needed I'll send my front axle to SID for a lower front stance. After the suspension then I'll focus on brakes and getting it running. Looks like I'll need to shorten the driveshaft by 1.5" - 2". I did notice that it will need king pin bushings which I've never done before so I'll need some help with the steps to R&R them. Thanks, Brian
PurdueSD Owning this truck has been an educational experience The oldest I've ever owned b4 was a 55 Belair, but I never did any suspension mods to it. The design of the pins and shackle assemblies are weird. Mine were frozen up and I spent 1/2 an hr beating in a new bushing. So on the balance (once my elbow and shoulder recovered) "grin" I removed the springs and used my hydraulic press and a lg socket and it was much easier. I'm waiting for Posies to send me a front spring that Classic Ind had shipped and "lost in transit"? Anyway I just placed an order with Summit for a remote brake reservoir so I don't have to deal with disassembling the master cylinder just to add brake fluid. My wife who is very supportive with my hobby is hoping the truck is road worthy for this years car shows and cruises
Nice looking truck. When I swapped rear axles on my 51 I flipped the springs (front to back) and then offset the axle about 1 inch forward.
SimpleStone, I noticed the change in offset from center when I let the weight back down on the springs so like you found its about 1" rear of center. Fortunately when I made my plates I made the spacing of 3 holes 1" apart for total of 3" of travel so all I'll need is to cut the overall length of the 1/2" plates down and install. I ordered universal lower spring plates to fit the new 3" U-bolts, but I've yet to fab a upper shock tower/crossmember and figure out what the overall length of the rear shocks I'll need.
I need help! I went to purchase a 86 S-10 rear axle for my 49 and the measurement from backing plates was 53.5" and it was out of a 4x4. The guy had a 2wd axle next to it and it measured 48" from backing plates. I'm wanting to switch from the 6 lug to 5 on 4 3/4". Is there something I'm overlooking? Thanks, Brian
Set your wheels in your wheel wells where you want them. Now measure the distance between the mounting surfaces. That's the axle width you'll want. If you need adapters to mate to your wheels, take thickness of those into account.
I haven't changed my chassis, I just want to change my rear axle to a 5 bolt pattern but keep the same width. I ordered the disk brake kit that's 5 on 4 3/4" and want to have the same for the rear. I've read that folks have used the S-10 "Blazer" axles and it's noted that they're 59.5" from backing plates but the 2 s-10 axles I viewed today and one "was said" to be from a Blazer 4x4 was only 53.5" wide. My plow truck is a 1987 S-10 4x4 Blazer so I'll confirm if its truly 59.5" tonight when I get home from work. If it isn't then I'll try and find a 1/2 ton C series chevy pickup maybe that would be closer to the 60" that I need.. Thanks
Update, I measured the dimensions between the backing plates and it's 53.5". So the s10 blazer 4x4 axle won't work. Leaning towards a 70's-90's camaro or firebird. From my research their spread is 59", but then everything thing I found on the blazer was 59" so not sure what to believe. .
...I use rearends that measure 61-62" wheel mount-to-wheel mount surface and use 8" rear wheels on these trucks, fit nice...(2nd generation Camaro/F-Birds, full-size GM's mid 70's- early 80's, with the 4 &3/4 bolt pattern, (some were 5on5)
That's good to know, and that's a sweet ride. But I'm still confused, my rear axle measures 60" (between) the backing plates. I stopped at a friends house who has 1st and 2nd gen camaro's and a 78 Z28 measures 54" between the backing plates. So the axle width that you have used would nearly fit in between the axle that's in my truck. However in your photo the axle looks great inside the wheel well. Do you know the backspacing on your 8" rims? Thanks
I must of had a senior moment because I went back and measured my rear axle and it's only 55". I have to wonder sometimes that I'm losing my mind, lol...
....don't know what these rearends measure backing plate to plate; I just know that wheel mount-to -wheel mount (outside of brake drum face) you need 61-62" with these 8" wheels, which have about 3 & 3/4 " backspace. with different wheels your tires may scrape the bedsides or the fender lip.
always measure wheel face to wheel face & back space of original to gauge by. took me a week of measuring rear ends before finding one wide enough to allow for transverse leaf to mount at correct spread for a model a. early s10 too narrow 95 on up perfect
I bought a 1981 Z28 with a 8.5 10 bolt posi and aluminum drums, I'm not sure of the ratio just yet but I cut the spring pads off and set in place. Tonight I'll set the truck down and so I can mark my driveshaft to be shortened and then set the pinion angle. It's coming together slowly but at least it's progress
...you should temp. bolt it in place, set the pinion, then measure for driveshaft.. leave about 3/4-one inch play at the trans.
Nice..there are a ton of dudes on here that know there stuff when it comes to these trucks. Maybe one day I'll be one of them but for now I am just a mooch....haha...
Posies makes a set of 3" drop springs that have the centering pin moved back 3". They ride great and made the 12 bolt swap a breeze. Even with the 3" drop spring, I've added a 2" block to get the truck even with the ifs up front. It took some doing, but it's finally sitting dead level.
Rusty1, I've always made sure that the suspension is compressed under standard ballast conditions before welding spring pads in place and marking cut lines for driveshaft. In my performance cars I generally set the pinion at a -3degrees but this is just a cruiser. This weekend I plan on running new front and rear brakelines then reassemble the front axle. I hate king pins so I'll save that for last I'd like to also give a shout out to Posies for fixing Classic Ind. screwup on my front spring order, truly a great group of (honest) guys!
I found a rim design that Summit has (Wheel, Torq-Thrust II, Polished, Chrome, 17 in. x 8 in., 5 x 4.75 in. Bolt Circle, 3.75 in. Backspace). Would this backspacing and width work for front and back? I took someones advice and ordered the 3" rear springs from Posies that offers the center pin offset to center the wheel in the wheel well. Thanks, B
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