Make it handle

[robnolimit]

HAHA, I never thought of a heavier one. - Now, if it bolted to the back bumber, I might take you up on that.

[TrueChevyTech]

Hey rob, care to do a make it handle on air post... similar to the one where you gave a cost efficient break down of the best bang for the buck on springs

[Hotchkis]

Originally Posted by robnolimit

HAHA, I never thought of a heavier one. - Now, if it bolted to the back bumber, I might take you up on that.

Robnolimit,

We're here to help. We'll see you soon.

[andrewmp6]

I'm still waiting to see someone use c5 suspension on one of these trucks.I know nate has a c4 dropmember and talked about making a c5 one but haven't seen any pictures yet.

[ajgriffin]

Originally Posted by andrewmp6

I'm still waiting to see someone use c5 suspension on one of these trucks.I know nate has a c4 dropmember and talked about making a c5 one but haven't seen any pictures yet.

Couple out there that are far enough along for you to see what it would look like, but both are on hold:

Frizzle Fry: http://67-72chevytrucks.com/vboard/s...d.php?t=179289
abadsvt: http://67-72chevytrucks.com/vboard/s...d.php?t=263426

[robnolimit]

Corvette suspensions is a whole topic on its own. If you started with a clean sheet of paper, and youset out to design the best handling lowered truck you could, it would end up looking like a Corvette with a little tiny bed on the back. - Every time. Now, we don't get a clean sheet to start with, so things are a bit more restricted. I will agree that Corvettes handle great, but they are Corvettes. The rears can be used in many applications with great success, but you have to pay close attention to the spring rates. When it comes to the fronts, I have a different opinion (remember, this is just my opinion) The thing about the front suspension is that the rack is mounted rather 'high' in the IFS. In a Corvette, this is fine, because the engine is behind the IFS, but in a pick up, the engine sits over the front suspension. So, with the Corvette IFS, it forces you to raise the engine an inch or two. So any gain in suspension gain is lost in the raising of of the engine, - C.G.

[andrewmp6]

I have seen the c5/c6 spindles and a arms used on f body subframes like art morrison and detroit speed.The rack height on them don't look really that much higher,But i haven't seen under a stock corvette in a while so no clue on heights to compare.

[hotroddr]

Originally Posted by robnolimit

Conumdrum This is where the geometry gets a little tricky. to start with, I'll let you know that the inner pivit point on the stock centerlint is 5/8" too high. - (or the outer tie rod pivit point is 5/8" too low). If you notched and raised the crossmember 5/8" things would be perfect. But, not low enough, I'd guess. So, if you raise it 1 1/2", you have a 7/8" mis-match. You can swap the outer tie rod ends for hiems, and put them on the bottom of the steering arm, but that is a 1 1/4" flip, so you would havs a 5/8" mis-match the other way. How do you fix it? Well, you could move the steering box and idler arm mount holes up 7/8". You could heat and bend the pitman arm and idler arm up 7/8" - I hear you cringing, but it is possible - You could do the tie rod flip, and bend the pitman and idler down 5/8" - be warned that the tie rod flip forces you to run an 18" wheel or bigger with drop spindles - You could check into the Hotchkis center link, but I don't know how much of a drop it has at the pivit points, You could build your own centerlink with the inner pivits in the correct location, and Lastly, you could get one of our new rack and pinion kits (shameless promo) that mounts to the crossmember, so the geometry stays intact with anty placement of the crossmember. Our JT has a 1 1/2" raised crossmember and a rack. wheew, lots of choices.
CJ leafs can work very well, just ask Mary Posi, 11 time national auto-x champ. Shortening the bed = shortening the wheelbase. This is good for corners at spedds under 80 mph, but starts to make the trucks twitchy at higher speeds

so If im reading this right, if one were to raise the crossmember into the frame 2 3/8" and flip the tie rod to the bottom side of the steering arm and switch to the heim joints, the bumpsteer would be dead on. What is the downside to this? I know the crossmember would have to be sectioned to clear the oil pan and there may be a few parts of the crossmember that would have to be clearanced for the steering linkages.

[robnolimit]

Hmmm, good thought. 2 1/8" would be the number. And, oil pan clearance would be a must. Now, if you do this, move the crossmember forward 1" to help fit the tire to the wheel opening. Use the BEST rod end you can buy. A high mis-alignment chromoly unit.

[SCOTI]

Originally Posted by robnolimit

Hmmm, good thought. 2 1/8" would be the number. And, oil pan clearance would be a must. Now, if you do this, move the crossmember forward 1" to help fit the tire to the wheel opening. Use the BEST rod end you can buy. A high mis-alignment chromoly unit.

Seems like a bunch of work though for the possible benefits.

The bumpsteer would potentially be better but the factory a-arm set-up would still limit caster & require further changes to optimize things. Moving the x-member forward to reset the spindle C/L within the well would prob require moving the steering gear as well. Moving the steering gear would prob interfere w/the radiator and/or core support mounts.

It could be quite the 'can-o-worms'.

[Scot_Douglas]

Originally Posted by hotroddr

so If im reading this right, if one were to raise the crossmember into the frame 2 3/8" and flip the tie rod to the bottom side of the steering arm and switch to the heim joints, the bumpsteer would be dead on. What is the downside to this? I know the crossmember would have to be sectioned to clear the oil pan and there may be a few parts of the crossmember that would have to be clearanced for the steering linkages.

If you section the 2 3/8 out of the center of the x-member, your relationship to the oilpan stays the same.

[hotroddr]

I may as well throw my tentative plan out there to see if there is something im not thinking of.

I am thinking I will move the crossmember forward 1" and raise it into the frame 2 1/8". For the upper control arm bracket, Im thinking I will raise it up the same amount but not move it forward at all so that I can gain additional caster without having to modify the lower control arms or cross shafts.

I will switch the outer tie rod ends to heim joints and mount them from below the steering arm. I think I will have to ream them with an angled reamer from below and use a tie rod to heim adapter like this one from speedway motors
http://www.speedwaymotors.com/Adjust...Heim,3333.html

Sound like a reasonable plan?

[Scot_Douglas]

Originally Posted by hotroddr

I may as well throw my tentative plan out there to see if there is something im not thinking of.

I am thinking I will move the crossmember forward 1" and raise it into the frame 2 1/8". For the upper control arm bracket, Im thinking I will raise it up the same amount but not move it forward at all so that I can gain additional caster without having to modify the lower control arms or cross shafts.

I will switch the outer tie rod ends to heim joints and mount them from below the steering arm. I think I will have to ream them with an angled reamer from below and use a tie rod to heim adapter like this one from speedway motors
http://www.speedwaymotors.com/Adjust...Heim,3333.html

Sound like a reasonable plan?

Check out the last page of my build thread - I did just that. Also, use this adapter - it is beefier than the speedway versions: http://www.bcbroncos.com/steeringlinkage.html

[Conundrum]

Originally Posted by SCOTI

Seems like a bunch of work though for the possible benefits.

The bumpsteer would potentially be better but the factory a-arm set-up would still limit caster & require further changes to optimize things. Moving the x-member forward to reset the spindle C/L within the well would prob require moving the steering gear as well. Moving the steering gear would prob interfere w/the radiator and/or core support mounts.

It could be quite the 'can-o-worms'.

I had thought of doing things just as you described a few months back, but I then decided to go ahead and Z my frame 2" for added drop and I could move everything forward by cutting the frame at an angle.

[SCOTI]

Originally Posted by Conundrum

I had thought of doing things just as you described a few months back, but I then decided to go ahead and Z my frame 2" for added drop and I could move everything forward by cutting the frame at an angle.

That's how I was going to do mine as well but w/no real gains for the factory geometry, decided a different route. A good combo would prob be the Hotchkiss set-up on a 2-3" Z'd truck. You gain precious clearance for the lower a-arms & crossmember plus the geometry is vastly improved.

This is why I look forward to Porterbuilts 'Touring DM' as well as what No Limts comes up w/based on their 'JT' track evaluations.

[robnolimit]

Let me chime in a bit.
1. As to air ride and handling, remember that an air spring is just that, a spring. You can tune an air spring in many ways, air pressure, air spring part chance, and by shimming the mounting surface. An air spring is a more 'pure' spring than a steel spring, and also, where a steel spring usually has a fairly constant spring rate, an air spring tends to gain spring rate as you compress it. This can be a handling plus, if you know how to tune for it. The biggest difference we see is that an air spring rebounds VERY quickly compared to a steel spring, so the shock need a bit more rebound control. Other than that, an air spring suspension can handle just as well as a steel spring truck.
2. I have to say we learned a ton of stuff building our J.T. project. And as we talk to enthusiests in the C-10 realm, we get a lot of different input. It seems that there are three types of truck builders. Basic bolt-on, advanced bolt-on, and all-out. The first two types are defiatley the most common, so the market says thats where we need to be, - mostly. I know we're slow at getting parts out to the market place. We test EVERYTHING, and it takes a while. We also try to plan in any changes that may have been made to the trucks already, so that the new parts will still work. Please be patient.
3. For the most part, please ask questions here. I get a lot of P.M.'s, and many are questions that everyone could benefit from. Don't be shy, I'll try not to make fun of them. Have a great day, and go work on your truck.

[leftcoast66]

Originally Posted by robnolimit

Let me chime in a bit.
1. As to air ride and handling, remember that an air spring is just that, a spring. You can tune an air spring in many ways, air pressure, air spring part chance, and by shimming the mounting surface. An air spring is a more 'pure' spring than a steel spring, and also, where a steel spring usually has a fairly constant spring rate, an air spring tends to gain spring rate as you compress it. This can be a handling plus, if you know how to tune for it. The biggest difference we see is that an air spring rebounds VERY quickly compared to a steel spring, so the shock need a bit more rebound control. Other than that, an air spring suspension can handle just as well as a steel spring truck.

Thanks for the info on this, I'm just starting building a bagged truck for handling. Any suggestions on companies to get shocks from? Would some QA1 be good because of the adjustability or is there a shock you would recommend more than others?

[ajgriffin]

I have a question about shortening a C4 rear. It is something that that I would like to do to get the wheel look I want. I've read about folks doing it, but never got a suspension engineering perspective on it. Is it possible, what would be involved and what are the side effects?
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[RANDOMIZM]

For an IRS, how much torque can they hold? Would 800+ft-lb be a problem for them?

[SCOTI]

Originally Posted by RANDOMIZM

For an IRS, how much torque can they hold? Would 800+ft-lb be a problem for them?

Depends on how that >800ft/lbs is applied (specifically, how quickly it's applied ).

[Scot_Douglas]

Originally Posted by RANDOMIZM

For an IRS, how much torque can they hold? Would 800+ft-lb be a problem for them?

Originally Posted by SCOTI

Depends on how that >800ft/lbs is applied (specifically, how quickly it's applied ).

That's a good question! That's why I'm using a T-5 transmission as the weak link. I think a trip over to Cobra forums might answer that - I know some people use a lot of the Ford IRS components in the kit cars.

[robnolimit]

SHOCKS I'd have to say that for me, adjustables are worth the money. - That being said, Bilstien shocks are the best bang-for-the-buck in general. I use all different kinds of shocks to get the valving the way we want it. Doetsch 3000 series (a pre-runner shock) is softer compression than most. Afco and Carrerra have split-valve shocks that work good too. As for the adjustables, we use Romic, Ridetech, Qa-1, Fox, and others. If you go with a single adjustable - rebound adjustment - then you need to watch the compression side. Since our trucks are nose heavy, and the front shock is leveraged almost 2 to 1, the fronts need almost twice the static compression compared to the rear. And, since most shock guys are 'car' guys, it's hard to find outside the 'race' relm. Oval track suppliers usually have more shock knowledge than anyone else around.

[robnolimit]

On the IRS vs. big torque, Thats thin ice. We built a trucks a few years back with 1200 hp. 1300 ftlb. and a Dutchman custom IRS. These are built with 9" ford centers, and even with all of the heavy duty parts, I beleive it would spit out a half shaft any time you really got after it. The t-5 may be the week link, but the clutch transfer is also more harsh than a torque converter. If you want to have a lot of fun with all that hp., put in a 9", or 12 bolt, with floating axles, and then hammer it without fear.

[Conundrum]

Hey Rob, I got a leaf spring question for you and i'm not real sure if it's been asked yet.....

There is 2 different length leaf springs for us 73-87 guys, a 52" & a 56".

Is there any advantages or disadvantages to either one of these, or would the advantages or disavantages of either be enough to worry about which one you have?

[robnolimit]

Hmm, now I have to check into this. IF, both of the springs are the same length from the axle center pin to the front eye, then I would choose the longer one. It will have a bit softer rate. BUT, if they are different, and the longer spring is longer from the pin to the front eye, then I would choose the shorter one. It would have less axle wrap, and better grip through the corners. Trick question, and I don't know what the spring measurements are. Any help?