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TnA's 86 Jimmy Shop Build / Product Development Thread - (Trailing Arms?!?!)
- Thread starter CFMi
- Start date
Darren, can I suggest that you make the rears have a few more hole locations more forward, and then the front hangers have a few more rearward. This would allow the springs in there now to be moved just a bit forward or back without different length springs etc.
Exactly!!
I thought about this quite a bit when I designed the rear... And I just couldn't come up with a reason that you would need a shackle bolt hole any further forward than where it is now (it ends up with a pretty darn good shackle angle with the axle in the stock location and the shortest springs in there). I could see an extra hole or two rear-ward on the front spring hanger, in case you wanted to move the axle back and still wanted to stick with the short 52" springs, but a zero-rate or leaf spring pads with multiple holes could do that also. I just didn't want to make these hangers soooo long that if you ended up with a 64" spring mounted in the forward-most hole that the spring would hit and bind up in there under hard articulation. It might just do that in severe cases as it stands now, but hopefully if your rig has THAT much articulation, you aren't running in the furthest forward hole anymore and your wheelbase is stretched a little. When I get the 64's in there, I'll see just how close things are under articulation and move forward from there.
-Darren
How much does it stuck out further past the factory hanger? Towards the front of the vehicke
You dune guys are silly, lol! Moving the axle forward?? That's craziness. More rear overhang? What if you drop off a large rock.... ....oh wait, you don't have any of those!! Just kidding man.
Anyways, if you look at the pic of the rear shackle and pay attention to the shackle angle, you can see that you could pretty easily move the spring forward in the hanger by at least an inch and still have a decent angle. That can be done as-is. If you need to go further forward than that, then I think the shackle angle would become too steep, and you would need a hole further forward on the rear shackle flip, like you suggested. Of course, you could always drill new holes for the flip and move it forward as much as you desire. With 52" springs mounted in the furthest forward position and the shackle flip drilled forward quite a bit, you could move your axle centerline forward a full 6". I think you'd almost have a wheel-stander at that point, you could maybe use the rear tire as a step to get in.
I shouldn't rag on you too much though about moving the axle forward, I know different setups work well for different terrain. Even street queens have their place and could probably benefit from exactly what you are suggesting. It's just so difficult for me since I'm always out here stretching wheelbase on rig after rig to get better approach and departure angles, and to get an ideal length for the rocks.
Well, the front bolt-hole is 6" forward from the stock hole, and then there is the material surrounding that hole too. I'll try to get some dimensions posted after I finalize the design a bit. It will only work on the Blazers since the gas tank on the trucks is right there. Maybe swapping out to a shorter gas tank (stepside truck maybe?) might allow it to work on the truck frames?
Okay, here is the current version of the 6-side-bolt style:
...And here are the dimensions as to how far forward it is, as compared to the stock leaf spring bolt hole location:
-Darren
Thank you! Hmmm now If I can have it in me to take a BFH to my 20 gallon tank.
Are you going to make an adjustable flip kit like that for 2" and 4"?
Martin
Martin
Yes sir! The 4" version is already released here: http://coloradok5.com/forums/showthread.php?t=308229&highlight=tna
And for a 2" version you could simply run the zero lift with a longer shackle
-Darren
It seems like offering a 2" wouldn't be much harder?
Martin
Martin
any progress made with the 64 inch swap?
Unusual ignition problem - SOLVED!!
Well, some progress has been made on the Jimmy, but the only thing I got done with the 64 swap so far is the nasty burning out of the factory bushings and the installation of the new poly bushings. So now the spring hangers, shackle flip, and the 64" springs are all ready to go, just have to get the Jimmy off the ground and swap the springs in. The problem with doing that at the moment is the fact that there is a 12,000lb scissor alignment rack stuck in my only bay at the shop with a lift. I have been refurbishing it for my other job, and although the main scissor rails of the rack are refurb'd and painted, I am just now finishing up all the accessory parts that go on the rack - and while I'm doing that, I had to keep the main rails inside out of the weather. So I've been pretty stuck for the last two weeks. I'm optimistic that the scissor rack will be leaving this coming week, so I'm hoping to get the 64 swap done next weekend.
In other news....
I finally figured out a problem with my TBI ignition system and I thought I'd tell you guys about it since it was something I have never seen in all my years with these systems.
I have been fighting a weird ignition problem for a while now in the Jimmy. It has a bone-stock 350 from a 1989 C1500 truck in it, complete with full wiring harness and TBI fuel injection system. It ran great right when I swapped it, but very shortly afterwards it started having some ignition issues. It seemed to me that the ignition module was the culprit, so I put in a new one. Ran great for a couple miles then coughed and sputtered again. Brought that module back and replaced it with yet another new one. Same thing. Put the factory GM module back in and it ran great, then a few miles down the road, same thing. Really strange. I threw cap, rotor, wires, plugs, new knock sensor module, etc... at it and still same issues.
Last weekend I printed out the full GM test procedure for the ignition system. I followed the flow chart to a tee, and I mean it was pretty invasive - we are talking about going so far as to pulling the computer, putting a specific resistance to certain pins and checking other pins to make sure things switched properly and crap like that. Checked all the wiring in the harnesses too, everything pointed exactly to the ignition module. So I changed it AGAIN, and - you guessed it - same problems. WTH????????????
So, as I was doing all this, one time when I put my hand on the distributor cap I thought I felt it move a little - much like the old HEI caps with the spring retainers - but this cap bolts down solid. So I checked the distributor against another one I had at the shop - an aftermarket one. The way these distributors are put together from GM is that there is an aluminum main machined housing shaft and a pressed on steel base that the cap bolts to. The GM one is simply pressed into place. The aftermarket one I had in my had was pressed on and then staked into place in numerous places around where the two meet. That in conjunction of my thought that the cap had moved made me look closely at things right there. My old distributor's pressed on steel plate was loose enough that it had rotated around the main base of the distributor and wasn't lined up properly any more. Although the magnetic pickup on the distributor tested properly, I can only assume that the mis-alignment of the cap to the base has been causing my problem all along - because after I swapped in the new distributor, everything cleared up instantly!! I even went so far as to swap in the original GM parts (from 1989!) that had been in there from the get-go, and with the new distributor in there, the truck runs awesome! Power is back, starting is flawless, and it even idles smooth as can be, without even a miss every once in a while like these systems so often have!! SO, as far as I can tell, the problem is FINALLY SOLVED!!!! Check your factory distributors people!!!
-Darren
Well, some progress has been made on the Jimmy, but the only thing I got done with the 64 swap so far is the nasty burning out of the factory bushings and the installation of the new poly bushings. So now the spring hangers, shackle flip, and the 64" springs are all ready to go, just have to get the Jimmy off the ground and swap the springs in. The problem with doing that at the moment is the fact that there is a 12,000lb scissor alignment rack stuck in my only bay at the shop with a lift. I have been refurbishing it for my other job, and although the main scissor rails of the rack are refurb'd and painted, I am just now finishing up all the accessory parts that go on the rack - and while I'm doing that, I had to keep the main rails inside out of the weather. So I've been pretty stuck for the last two weeks. I'm optimistic that the scissor rack will be leaving this coming week, so I'm hoping to get the 64 swap done next weekend.
In other news....
I finally figured out a problem with my TBI ignition system and I thought I'd tell you guys about it since it was something I have never seen in all my years with these systems.
I have been fighting a weird ignition problem for a while now in the Jimmy. It has a bone-stock 350 from a 1989 C1500 truck in it, complete with full wiring harness and TBI fuel injection system. It ran great right when I swapped it, but very shortly afterwards it started having some ignition issues. It seemed to me that the ignition module was the culprit, so I put in a new one. Ran great for a couple miles then coughed and sputtered again. Brought that module back and replaced it with yet another new one. Same thing. Put the factory GM module back in and it ran great, then a few miles down the road, same thing. Really strange. I threw cap, rotor, wires, plugs, new knock sensor module, etc... at it and still same issues.
Last weekend I printed out the full GM test procedure for the ignition system. I followed the flow chart to a tee, and I mean it was pretty invasive - we are talking about going so far as to pulling the computer, putting a specific resistance to certain pins and checking other pins to make sure things switched properly and crap like that. Checked all the wiring in the harnesses too, everything pointed exactly to the ignition module. So I changed it AGAIN, and - you guessed it - same problems. WTH????????????
So, as I was doing all this, one time when I put my hand on the distributor cap I thought I felt it move a little - much like the old HEI caps with the spring retainers - but this cap bolts down solid. So I checked the distributor against another one I had at the shop - an aftermarket one. The way these distributors are put together from GM is that there is an aluminum main machined housing shaft and a pressed on steel base that the cap bolts to. The GM one is simply pressed into place. The aftermarket one I had in my had was pressed on and then staked into place in numerous places around where the two meet. That in conjunction of my thought that the cap had moved made me look closely at things right there. My old distributor's pressed on steel plate was loose enough that it had rotated around the main base of the distributor and wasn't lined up properly any more. Although the magnetic pickup on the distributor tested properly, I can only assume that the mis-alignment of the cap to the base has been causing my problem all along - because after I swapped in the new distributor, everything cleared up instantly!! I even went so far as to swap in the original GM parts (from 1989!) that had been in there from the get-go, and with the new distributor in there, the truck runs awesome! Power is back, starting is flawless, and it even idles smooth as can be, without even a miss every once in a while like these systems so often have!! SO, as far as I can tell, the problem is FINALLY SOLVED!!!! Check your factory distributors people!!!
-Darren
Don't let him fool ya', the 2.5 shackle flip is VERY nice! I especially love the linked backing nuts, makes install so much easier.
I was able to install them WITHOUT pulling the fuel tank. First you pull the bumper, then remove the old crap. Install the brackets using the bottom bolts which you can reach between the tank and frame. Then using a little tape and a metal yard stick you can get the side bolts done. Tighten and profit!
Thanks again TNA, the brackets absolutely rock!
I was able to install them WITHOUT pulling the fuel tank. First you pull the bumper, then remove the old crap. Install the brackets using the bottom bolts which you can reach between the tank and frame. Then using a little tape and a metal yard stick you can get the side bolts done. Tighten and profit!
Thanks again TNA, the brackets absolutely rock!
Rear 64's are in!
Okay guys - I finally have access to my lift again, and I took an hour yesterday to swap in the 64" springs. With the bushings already replaced in the 64's, and the front spring hangers and the adjustable zero-lift shackle flip already installed on the truck, that's all the time it took! I put the front of the 64's in the very first hole in the spring hangers, and moved the shackle back to the last hole in the shackle flip, then bolted the axle back to the new springs, and sat her down on the ground. Measuring before the swap, the rear sat at an average of 39.75" from the ground to the wheelwell at the centerline of the tire (with bone-stock springs and 4" blocks). After the swap, with the same blocks and everything, the truck measured 38.75" at the same spot. SO, I lost almost an exact 1.00" of ride height. That is absolutely perfect, since the zero-lift shackle flip has 4.5" shackles to keep it at zero lift - now I can run a 6" shackle for some additional travel capability, and with the added length of the shackle along with the slightly less shackle angle it will provide, I should be just about perfect ride height. And, with this setup, even with a 6" shackle, it still doesn't hang down past the gas tank skid at all. I couldn't be happier with the results!!
FYI - the rear 64's I used are from a C1500 2wd that was in good shape and have 3 main leafs and an overload.
Pics:
-Darren
Okay guys - I finally have access to my lift again, and I took an hour yesterday to swap in the 64" springs. With the bushings already replaced in the 64's, and the front spring hangers and the adjustable zero-lift shackle flip already installed on the truck, that's all the time it took! I put the front of the 64's in the very first hole in the spring hangers, and moved the shackle back to the last hole in the shackle flip, then bolted the axle back to the new springs, and sat her down on the ground. Measuring before the swap, the rear sat at an average of 39.75" from the ground to the wheelwell at the centerline of the tire (with bone-stock springs and 4" blocks). After the swap, with the same blocks and everything, the truck measured 38.75" at the same spot. SO, I lost almost an exact 1.00" of ride height. That is absolutely perfect, since the zero-lift shackle flip has 4.5" shackles to keep it at zero lift - now I can run a 6" shackle for some additional travel capability, and with the added length of the shackle along with the slightly less shackle angle it will provide, I should be just about perfect ride height. And, with this setup, even with a 6" shackle, it still doesn't hang down past the gas tank skid at all. I couldn't be happier with the results!!
FYI - the rear 64's I used are from a C1500 2wd that was in good shape and have 3 main leafs and an overload.
Pics:
-Darren
You are very welcome, my friend!!
very cool 
thank you for the write up and thank you for giving me some ideas
are you going to do a four inch flip and get rid of the blocks?
thank you for the write up and thank you for giving me some ideasare you going to do a four inch flip and get rid of the blocks?
y5mgisi
1 ton status
Looks awesome!
