2.25" Leaf Spring Flip and Upgrade

[sKnNyPpY]

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.



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.



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.



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.



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).



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.

[lolife99]

Great write up for the leaf spring truck guys.
Thanks!

[sKnNyPpY]

Many of your threads and comments helped lolife. This forum is PRICELESS

[oldman3]

Thanks much for posting your work and the outcome. Will be starting a 68 GMC with leafs soon and this is a big help. Thanks again...Jim

[duallyjams]

Originally Posted by lolife99

Great write up for the leaf spring truck guys.
Thanks!

x2

[tommyd241]

Great write up! Thanks for sharing!

[hpcgmc]

Great writeup, Thanks! I'm just about to do the same thing, and am weighing flip kit vs. drop leafs.

[sKnNyPpY]

If you do the drop leaf I would still replace the shackles so you get the new bushings. I hear bushings are about $15 and the shackles with bushings were only $25
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[INSIDIOUS '86]

Be nice to your djm flip kit
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[sKnNyPpY]

The brackets for the 2.25" flip kits are a lot more substantial than that.

[WarMonger]

Bump this up to the top. Great write up on a flip kit. Do you remember the part number for the shocks you used?

[sKnNyPpY]

Should be Monroe 37049ST http://www.summitracing.com/parts/mo...5-c1500-pickup

They are a little soft, but have held up nicely while being driven "spiritedly", and are real affordable, especially with all the rebate Monroe does.

[PaPaStewySnipes]

Wow! This forum is great. Thanks for your time spent in making this thread. I have a 71 gmc long bed with same 3/1 set up as you and have been searching for days for this info, just got my truck few months back and it is busting knuckle time. I have been under the truck several times with a tape guessing what would happen if I flipped my 3/1 leafs. Just looked as if it would be to close to the frame as opposed to other flips I have seen, I even contacted previous owner to ask if rear was stock because it wasnt adding up properly. After doing what you did, would lowering springs be cheaper, with same effect. I am running 18s tt2s and having the very same issue you had. I'm doing a full upgrade on the front as well all new. Any additional input would be very helpful to me. I will mass order what I need this weekend. Hopefully it will turn out as nice as yours. Some pics below of what I'm working with at the moment.

[sKnNyPpY]

Sorry for the late reply. If you haul anything I would go with replacement leaf packs like I did and a flip. I still haven't notched and occasionally haul loads with no problems and little bottoming out. If you are just cruising I would go with lowered leafs for ease of install and all new stuff vs. flipping old questionable leafs.

[PaPaStewySnipes]

I have some on the way, ece 4" drop leafs coming in tomorrow. They should have been droped off today but fedex is b.s.

That will give me 4" drop. I was thinking about going with Djm shackles. Those drop 1.75"-2". They have 2 holes to adjust that 1/4".

[PaPaStewySnipes]

Already have my front 3" Belltech drop spindles and 1" drop springs just getting front ready now, adding a new wilwood mast and prop as well. Hand bending some new lines also. Some pics below, I did that all yesterday.

[sKnNyPpY]

Good work brother, and good choices! I wish I had cleaned up my parts a bit better like you did. New shackles stock or drop will give you new bushings, but you can install with the old to see if you like a rake or not before ordering.

[sKnNyPpY]

I live in West Cola, but drive the truck in to Rosewood quite a bit. I work at The Cigar Box Rosewood Drive.

[PaPaStewySnipes]

Eactly, I havent ordered shackles yet but I can get them in 3 days, better to see what the look will be. I have a wilwood rear disk kit, and new willwood d52s for front. Will look nice so I couldnt live with putting that hardware on some dirty and rusted control arms. I used purple power for clean up, wire wheel on drill, srayed some vinegar, water, krud kutter the must for rust mix for rust conversion. Laid 2 coats of rustoleum reformer, top coat with but chassis black. Used heater while doing to keep parts warm to hot, came out really nice.

[PaPaStewySnipes]

I didnt realize your in Columbia sc, lol. I'm in irmo by mall.

[drfloyd]

Good to see a couple of SC guys not too far away.

[PaPaStewySnipes]

Just got the bad boys in, next to them is my refinished control arms for drivers side. Getting back to work on the front suspension and brakes today.

[gsxrcop]

Will this flip kit work on a 71 3/4 ton 2wd?

[sKnNyPpY]

I think the 3/4 leafs are wider than the half and this won't work. You'd have to fabricate one.

[gsxrcop]

I just checked and the leafs are 2.25" wide. Thanks for the help.

Originally Posted by sKnNyPpY

I think the 3/4 leafs are wider than the half and this won't work. You'd have to fabricate one.