The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > General Truck Forums > Suspension

Web 67-72chevytrucks.com


 
 
Thread Tools Display Modes
Prev Previous Post   Next Post Next
Old 04-26-2013, 05:28 PM   #1
sKnNyPpY
Registered User
 
sKnNyPpY's Avatar
 
Join Date: Sep 2012
Location: Columbia, SC
Posts: 549
2.25" Leaf Spring Flip and Upgrade

Well I finally finished the drop on my 71 GMC long bed with 2.25” leaf rear and decided I’d summarize since the information was pretty spread out. Thanks for everyone’s input and suggestions. I’d already done the front 2.5” CPP drop spindles with 1” drop springs when I replaced the front rotors, pads and bearings and was riding with quite a rake for a while. The ride was fine but I couldn't see anybody right behind me.

Name:  2012-12-29_12-13-18_841.jpg
Views: 4790
Size:  58.7 KB

I used the DJM FK1012-5 flip kit and Monroe Sensa-Trac front sized shocks as drop shocks. You need at least two sets of jack stands, a floor jack or two, and I had a jack stand jack that really came in handy. A regular set of socket wrenches is great for working on the Sentra, but you need some big wrenches to work on this suspension. A 15/16” deep socket, a 15/16” ratcheting box end wrench and a 7/8” box end wrench really came in handy for the flip kit. An Irwin step bit was great for drilling out the shock mount bracket and the frame for the bump stops.

I did the flip kit at a buddies shop and his impact wrench was great for breaking loose the old rusty u bolts and spring and shackle bolts. I also used about a can of PB Blaster. After jacking up the truck to rest the frame on jack stands in front of the wheels I jacked up the axle to rest it on jack stands, too. The jack stand jack was great to move around and release tension at various points. The shocks came off easily with regular sized sockets, the impact broke loose the leaf spring bolts, but the u bolts I had to go back and forth with the impact to get them off. They were all rusted and stripped to hell.

I was mostly working by myself and it took me about four hours to get everything off and bolted back together. I left the springs bolted to the shackles and they came out with a sudden thwap against the underside of the bed. The leaf spring center pin came out easily to reverse (which I don’t believe was mentioned in the directions but was mentioned in another user’s post). I didn't have a stand under the drive shaft and the pinion angle was pretty extreme after bolting everything up. Ends up I had two short bolts and two longer bolts on each side of the axle locator bracket and upper axle plate, after reading the directions the 3.5” bolts go in the front and 4” go in the back. After wrestling with tightening and loosening bolts to try to get the pinion straight I gave up, put the new shocks and tires back on and lowered the truck. I was eating pavement it was so low, no travel and axle slamming into the frame all the way home because I hadn't re-installed the bump stops.

Name:  IMAG0501.jpg
Views: 3900
Size:  51.0 KB

After consulting the experts (you guys), I pinpointed a few possible problems: 1) Were drop shackles previously installed? No, new shackles were ordered and they were the same as the ones already on there, but I kept them because they had new bushings already pressed in and I bought new grade 8 bolts, too. 2) Were some spring leafs already removed? Maybe, my friend’s ‘71 is practically identical to mine and both of us have 3leaf/1helper setups, but factory replacements come 5/1. 3) Shocks need to be relocated to a more upright position. 4) Bump stops need to be trimmed/reinstalled and I hadn’t drilled the frame and installed the button stops that come with the flip kit.

The first thing I did was relocate the shocks. After a bit of digging a fellow member mentioned drilling out the hole directly behind the stock mounting stud and bolting on a new one. I used the step bit to drill out the holes and a stock Monroe mounting stud that came with the new shocks. I had to buy a replacement 5/16” nut because the ones that came with the stud didn’t thread all the way down and lock washers (which I didn’t initially use and lost one of the nuts). Bolted up the shocks and voila, I had some suspension travel. I reinstalled the factory bump stops but I was basically riding on them. I could drive this way but it was bouncy and pretty jarring when hitting the bump stops, which happened a lot. I trimmed the bump stops 1” with my band saw and the ride was (almost) tolerable, but I was still a bit too low in the back for my comfort and front ride height. A c-notch in the back and 2” drop springs in the front would have probably set me straight but I went in another direction.

Name:  IMAG0817.jpg
Views: 3787
Size:  26.0 KB

I knew I wanted to raise the back an inch or two, and wasn’t looking forward to drilling/cutting the frame for a notch, and I needed to drop the springs to drill the frame for the button bump stops anyway. I also already had new stock shackles with bushings and replacement bushings for my 3/1 leaf pack were like 4 X $14.00 each and would require some work to get them out/in, so I decided to replace my springs with a new 5/1 pack with bushings already pressed in. I spent an evening dropping out the old springs and another drilling the frame to put in the button bump stops and new springs. Boy, I’m glad I did. It’s like riding on silk, firm and smooth with no bottoming out. It only raised the rear about 1” so I might still put the 2” drop springs in the front, but there is no rush on that. I have about 3” of shock travel and went over speed big bumps and the back handles them better than the front now.

Name:  IMAG0828.jpg
Views: 3605
Size:  54.5 KB

So quick summary: DJM flip kit ($130 Summit), Monroe Sensa-Trac front size ($60 Summit but with a rebate to come), shock relocate ($4 in nuts/washers), button bump stops , new shackles and springs with bushings and bolts ($60 SD Truck Springs), 5/1 leaf spring pack with bushings ($350 shipped in 2 days from General Springs KC, made in the USA, baby) = about a 6” drop and a whole new rear suspension for about $600 plus some additional tools in the garage ($30 step bit and $50 in additional sockets and box end wrenches from Ace Hardware).

Name:  IMAG0837.jpg
Views: 3516
Size:  63.8 KB

If you have the 3/1 pack you could save some money by c-notching with quite a bit more sweat over replacing with a 5/1 pack but I stick with my decision of the new pack. I know there are also drop leaf springs available but I already did the flip kit and couldn’t return it used, and I have no idea how the ride is on drop leafs. My set up can also still be reversed if necessary.
__________________
Life is too long to go slow...
71 GMC 1500 Super Custom LWB
350/350 AC(replaced w/vintage air)/PS/PB
2.5 CPP Spindle, 1" CPP Drop Spring, CPP Front and Rear Sway Bars/DJM Flip, new General Spring KC 5 spring pack, HEI /IntReg Alt
20x8.5 OldSkools 5" BS, 275/45 Falkens
sKnNyPpY is offline   Reply With Quote
 

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 07:48 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com