Re: Make it handle
 

Rob what Ratio would you think would be best?

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What are these rear link bars attached to the ends of the trailing arms for? I have an idea, but have never seen this before. This is Speedway's G Comp Camaro.

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Watts Link.

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Looks to me like he's referring to the longer links/bars the attach to the truck arm & then to frame mounts located near the rear valance.

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Yes, the link bars that are attached to the trailing arms. Not the watts link on the rear axle.

Re: Make it handle
 

These are the 'Brake rods'. This is circle track stuff. The caliper is mounted on a 'Birdcage', which floats around the axle tube. When the brakes are applied, the brake force goes through the rod into the chassis, instead of a caliper mounted directly to the rear axle. Which, when the brake is applied, tries to rotate the axle, upsetting the suspension and tires.

BTW, I run a Birdcage on the HellBoy. Changing the angle of the rod changes the way the brake force loads the chassis/tire.

Typically, these rods are on the top of the housing running forward. Speedway 'flipped' theirs upside down for packaging. - no room to put them up top.

Re: Make it handle
 

My brain just exploded!

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Thank you for the reply, now I can sleep tonight :lol:

Re: Make it handle
 

Back track a little?

Was there ever a consensus on rear sway bars for stock trailing arms? At first it was yes, then no?
Also Rob when you fit a front sway bar are you fitting for frame or Lca? I have a 65 with 73-87 control arms. I talked with Tina and she didn't think your kit would work but I could've confused her. Thanks sorry to back track!

So with birdcages and 4 bars on cars that turn left and right can you get some rear steer both ways? When we used to do dirt stuff we could get a bunch of rear steer but that was just left or is it just to un load the rear end. I kinda don't get the bird cage lol. Ok I should pay attention sorry!

Re: Make it handle
 

As a base, I would say, yes, a rear sway bar will help on a stock arm truck. The rate should be low, under 150 lbs. Now, as these trucks get lower, the springs get tighter, the travel is less, and the roll center is effectively higher, (unless changed) and the rear bar is less effective. I know it's not a concrete answer, butthat's our experience.

Our OE base front bar should work, but you may need to mod the tabs (mounting points) on the Lower Control Arms to attach the links.

Yes, you can set a 4-bar, and/ot Birdcage 4-bar to steer both left/right, not as much as the circle guys pitch then, but it can be done. It is reasonable to achieve 1 or 2 degrees of 'roll steer' in the rear. even a small amount can change the truck from 'really loose' to 'really tight'. This stuff gets really complicated, and the oval guys have broken down the rear suspensions to have very specific components for each action of the suspension. Birdcage mounted 4-bars to only control axle position, and rear steer, a torque arm to control forward bite - with a shock and damper to control the tire set, 5th link and shock to control forward axle rotation, and floating brakes, and rod to adjust tire load under braking. ......... Go look under a fresh Modified or Late model dirt car and your brain will start to smoke.

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Since there aren't a lot of questions...start from the start and ask about the frame.i love the modification you did to the rear frame rails or your back rail kit, that raises the spring perch 4 inches. I love how you pied /stretched the stock frame that's just smart and dirty! But...Would it be as effective or in some way "off" if you didn't recess the front crewmember or use a wide ride? I guess I was wondering if the overall measurements and or the overall design was based upon them working front and rear? My truck is so low (cool) that I effectively removed all the suspensions ability. Your rear end is really smart and pretty easy in the grand scheme of things! Real hot rodding! Any chance of a link or brief explenation of how to recess the crossmember? Really apreciate and enjoy this information. Makes you want to go racing!

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Hey Rob,

Can you touch on boxing frames and X-braces? I seems like there is some key areas to box vs boxing everything. Also if boxing the whole chases is a X brace needed?

I have your guys trailing arm kit and the frame is some tight it is hard to fit a X brace where the trailing arms want to live.

Thanks Nick

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Just finished reading this for the 2nd time, thanks to Rob and everyone for the input. I have a 65 c10 swb, trailing arms, 2.5" and 1" spindles and coils , 3 " lowering springs, sway bars front and rear, Ridetech HQ series adjustable shocks, Lee's power steering, disc brakes. Currently flipping trailing arm brackets and interested in new a-arms. Any recommendations for my DD and occasional parking lot salomer?

Re: Make it handle
 

I've been following along during the build of my 66 and have been autocrossing it the last year and a half. Well, as much as the weather here in the NW permits :lol:. I did quite a bit of work to the rear suspension this last winter, installed the No Limit rear shock relocation kit, flipped the trailing arm brackets, swapped the 12 bolt for an 8.8 and the POL panhard bar kit and feel like I'm fighting the truck now. I noticed a lot of body roll in my first autocross in March but without a rear bar, I was expecting it. I took the truck to LS Fest West over the weekend and was struggling with the truck both days, so much so that I tried removing the rear sway bar and then ultimately flipping the trailing arm brackets back to the stock location. Flipping the brackets got me a full second faster but I still was feeling that I was holding back because of the truck. I'm new to performance driving and I don't expect that I'm maxing the truck out yet but maybe I am. Specs of it are:

CPP 3" drop springs and spindles up front
C10 front sway bar
CPP 5" drop springs and 2" blocks in the rear
Stock Trans Am WS6 rear sway bar
KYB Monomax shocks all around
No Limit rear shock relocation
POL longer panhard bar
275/40r18 Hankook RS-4s all around
Stock frame, not boxed

I have QA1 taller upper balljoints to put in and then I also want to do the caster mod on the lower control arm pivots but I'm wondering if I should focus my efforts elsewhere. I'm also a guy that would prefer to do stiffer springs over sway bars and I'm also on a pretty tight budget, hence the options I've done, but I can do most any fabrication myself.

Are there any mods that are obvious that will help out more than others that also don't break the bank?

Here's a picture from the autocross in March, I did not have a rear sway bar here but I did flip the factory trailing arm mounts over:
https://farm5.staticflickr.com/4781/...11c7442d_b.jpg

Here's a picture from LS Fest after I put the trailing arm brackets back to stock and put the rear bar back on:
https://farm1.staticflickr.com/910/4...94bc23a2_b.jpg

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Bummed to hear that it didn't all pan out but I suppose that's part of the process right? So what's it doing? Pushing ? Loose? I bet if you gave some details some racers would chime in. Seems like now your to the point where you need scales and springs to suit conditions ECT. I had a very brief stint (2 seasons, 2 cars lol) in a modified dirt car. Well man the tuning went on for ever with weight and springs and shocks and tire pressure and you know the rest. It may not be the most popular thing to say on here either but it is a old truck after all. If you've seen robs race truck before you'll know it's scratch fabricated tube chassis and dedicated racing suspension parts. I don't think these stock parts can go that far. Next I think would be coil overs and control arms but there goes the budget. Maybe the local dirt track guys could help scale the car and work on spring rates and shocks with ya. Those hillbillies know a lot about that stuff. I had started down the road but if you really really want to go fast and maybe even win it becomes a different game. I did the caster mod and it aligned at 4.5 degrees so thats cheap . It's a far cry from the race stuff though. Seems like to that staticly lowered isn't as optimal as the trucks with dropmember and raised rails. Seems like they have an easier time with springs. Again not very practical. Shoot I hope Rob comes back on you've done so much killer work would love to see you do good! Hmm...I have a dead crossme.ber I'd gift to you if you wanted to try the chopped up recessed thing. But my honest thought is the qa1 front coil over deal. You can do just the lower to start and build from there? Need a second job or sugar momma though! Well at least your out there and that is very cool!!! You'll get it Better and better I betting! Ok bump for rob

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It was one of the most eye opening experiences I've had with the truck and I have learned so much from getting my butt kicked. The added anti-squat has seemingly made the front and rear suspension unbalanced and was causing the truck to dive to the outside front tire which was giving me traction issues out back. The hard to understand part is that adding anti-squat reduces roll but it was causing more roll on the front end. The front springs I have now are an 1100 lb rate, 85 lbs heavier than factory according to CPP, and the front of truck is very soft. Hotchkis has some 1400 or 1500 lb springs that would work but I don't know if I will see gains due to the rest of the truck being stock. I've got access to scales at work, I'll dig through my pictures to see if I have a shot of when I put the truck on the scales.

Re: Make it handle
 

Since you're on a budget, throw some progressive bump stops on the shock shafts if possible to firm up the spring rate for only a few bucks. I've used '99 VW New Beetle rear bump stops (pn 1J0512131C, less than $5 bucks each on Rockauto) on lighter cars to limit body roll without increasing the base spring rate. That keeps the suspension softer to absorb mid corner bumps better but increases roll resistance without the drawbacks of stiffer springs or heavier sway bars.

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Also, what alignment specs are you running? Looks like you could use more negative camber up front. The taller ball joints will help with increasing the rate of camber gain as the suspension travels, but more static camber may help as well.

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Thanks for the suggestions!

I'm maxed out on camber and caster, I'm like 1.7 degrees negative camber and 2.5 degrees of caster. That's why I picked the ball joints up and want to do the caster mod. I'd like to be 2.5 degrees of negative camber and 5-6 degrees of caster.

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Here is a shot of my truck on the scales, this is the truck only and no driver.

Re: Make it handle
 

Yes, we could have used a WideRide or raised the front, or used the normal spindle/spring drop in front. While the two ends work together, there is more than one way to skin a cat. When it comes to handling performance, matching the roll centers ft/rr makes a difference. For cruising, you won't notice it much. Raising the front crossmember is easy. Unbolt it, cut a notch in the bottom of the frame 1 1/2" up, (while you're at it move the crossmember forward some to center the wheel) and weld it back in. New motor mounts and a notch for the oil pan will be needed.

Re: Make it handle
 

OK, the weight is not too bad, for a C10.
Here are some thoughts.

Anti-squate is a trade off. The higher mount will have more forward bite, but less 'brake-bite', and the lower mount will trade forward bit for brake bite.
I'll take a guess that on you're "aggressive" laps, you were trying to "go in deep" in the corner. That never pays off on street tires. Braking early, going in smooth, and getting on he throttle early on the exit pays off big time. This may be part of the lap improvement when you were taking it easy.

Roll center will get more and more important. The rear roll center is at the center of the panhard bar. Since one end is mounted to the housing, the rear roll center doesn't drop much when lowering the truck. The front roll center is generated by the IFS geometry. Drop spindles lower the RC the same as the amount of drop. Drop springs have an even greater effect. Tall ball joints usually raise the RC a bit. Let's say the truck had a balanced RC when stock. Lowering the rear 7" probably only lowered the rear RC about 2" (Not sure about the POL bar). Lowering the front 5 1/2" probably dropped the front RC 7" (just a SWAG). So now, you have a 5" imbalance on the RC line ft/rr.

Keep this in mind. Roll center work with the mass (weight) of the truck. The farther the RC is from the weight centerline (usually about the camshaft height) the more the truck will want to lean. (body roll) shifting weight to the outside tire. If the RC was equal to the weight height, there would be very little roll. - BUT, also very little side bite loading of the tire, which can help grip in the turn. Again, it's a trade off. Sway bars can be used to 'fool' the truck about the roll center, but this is a band aid and has other negative effects. ** THERE IS NO SUBSTITUTE FOR GOOD GEOMETRY **

So, what to do. Do the caster mod. you need 6 to 8 degrees. No money spent. Try some tall ball joints. Uppers only. Find a 73-87 front sway bar from a 1Ton dually. Or look for a bigger one from Helwig. You could also try a stiffer front spring, maybe Hotchkis) remember that the bigger bar and stiffer springs are just band aids for poor geometry. You can make it better, to a point. Consider our low roll panhard bar. this will drop the RC, and the truck will want to lean in the rear, but then you can hook the rear bar back up.

OK, this needs to be said. Sorry in advance. There are a lot of parts available for the C10 front suspensions. Some make fantastic claims as to performance/handling/ride quality gains. Lets be brutally honest. The OE crossmember sets the inner pivot points of the suspension. The spindle sets demands on the outer pivot points. So, what can you honestly get from these parts? 1. Maybe some increased Caster, if the arms moved the lower ball joint forward (this will come with more bump-steer due to raising the steering arm). Some have re-worked the upper mount to increase the camber gain, BUT, this approach also increases Roll Center Migration - not so good. 2.Converting to Coil-Overs. This will usually get you a better shock and an adjustable spring mount, BUT most have less suspension travel than stock. Not so great, but, short springs on the OE arms also limit travel. Less travel = Less ride quality. And, if it was done for the quality of the shock, put a great shock on the OE mounts. Why am I saying this? Well, it's not for the hate mail. Be Honest about your build. If you are working with a stock crossmember, do a spring and spindle, caster mod, new bushings/ball joints, and GO. But, if you want more performance than what that will offer, STOP. STOP wasting money on the OE geometry. You will have more $$ invested in the OE crossmember than it costs to step into something that actually works. It sounds harsh, but it's the truth. Write it down.
Spindles 300 - 850
Sway-Bar 250 - 400
Tubular arms 800 - 1200
Coil-Overs 500 - 1500
Rack and Pinion 950 - 1700
Brakes 300 - 2200
So, for somewhere between 3100 and 6500 bucks, you can work over your OE based IFS. And, the crossmember will drag the ground, and the geometry will still suck in comparison to something designed in this century. Take a moment to understand large scale manufacturing. The C10 chassis design really started in 1960 (same IFS geometry as 63) they started selling in 1959. So, parts production started in early 1958, late 1957. That means prototyping happened in early 1957, So, final designs were done in 1956, and concept drawings were done in 1955. Farms, dirt roads and bias ply tires. It is now 2017. This design is 62 years old. Those of you who think it can be tweeked into the modern hi-performance realm should throw out your smart TV in favor of a console black/white, with tubes and rabbit ears.

Sorry to jack the thread, but it is very important to understand the truth of what these IFS designs can, and can not do. Yes, mod them, race them, drive them and have fun, but know there will be a wall you can't get over. :smoke:

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Thank you for the information, Rob! I was starting to feel like that I am approaching or at the limit of what the stock suspension can handle. I unfortunately will be stuck with it for a while but your response what exactly what I needed to hear; I can keep throwing money at a setup with terrible geometry or keep it as-is and save up for a better setup.

I still have a few more times to read through everything you wrote to get it to sink in but thank you so much for answering my questions :metal:

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Rob,

OK, After reading thru you post (#1947), I have another approach I would like some advise on for my next build. I have a bunch of parts already just waiting to be used, so here is what I plan to put together. This would work for any '63-'72 truck since the suspensions are the same for those years...

Front:

Recessed the stock cross member up into the frame 1.5"
Porterbuilt Forward Lower arms (2013 versions)
Stock Upper Arms
Air Bags (could go to stock coil springs)
13" C4 Corvette Brakes on 2.5" drop spindles (from way2lo)
Upper Shock Mount relocated
Shocks - Would like to use Ridetech HQ series adjustable shocks, OR? (Don't have shocks yet)
1.25" Porterbuilt sway bar for the forward arms
No Limits Steering Rack Conversion Kit


Rear:

Modify rear rails (like you did with JT) to lower the rear
Air Bags (could go to 2"-4" lower coil springs)
Pan Hard bar - From mount is extended and has multiple holes for setting height, keep it long so that it mounts to Passenger side Trailing Arm at the end, Mount has 3 locations to help set height and keep the bar parallel at ride height.
Sway Bar - Don't have this yet so I am open to suggestions, Price might be a deciding factor.
Brakes: 12" C4 Corvette single piston, with drum in hat parking brake.

At this point, I am planning some sort of 18" or 20" wheel/tire combination, just not sure on tire sizing for the front or rear, any suggestions?

I fully understand that the performance of the suspension with be limited, but at this point so is my driving :lol: The truck will mostly be a fun driver that I can daily if I want to, but there will be an Autocross event for fun (Good Guys, local events, etc...) from time to time...

What other low cost changes would you recommend to maximize what I have to work with already? Taller Upper Ball Joints, etc...

Any advise would be great, I have a bunch of parts that I want to use and only spend money (with in reason) on what I don't have on hand to build my next truck.

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Rob,

Thank you for the wealth of information you have unselfishly provided here. Prior to reading this I was thinking I could modify my stock suspension enough to reach my goals but you have a future customer now. For the same money as other stock frame suspension mods on the market, I can get corrected geometry suspension using the Wide Ride IFS and Rear Fat Bar systems from No Limit.

While I'm saving up for this upgrade I have all of the basic knowledge of what can be expected from stock parts and cheap mods. Awesome, awesome thread!

THANK YOU!
-Pat