Make it handle

[doublebeetx]

Hey Rob I have a question. I see that 2 inch blocks aren't recommended for a truck with 15 inch wheels, I assume because they push the arms too low. Would 4 inch springs and a 1 inch block have a similar effect as the 3 inch spring and 2 inch block ?

[tubbedII]

Originally Posted by doublebeetx

Hey Rob I have a question. I see that 2 inch blocks aren't recommended for a truck with 15 inch wheels, I assume because they push the arms too low. Would 4 inch springs and a 1 inch block have a similar effect as the 3 inch spring and 2 inch block ?

Yes to all...(Sorry I'm not Rob, but...)

[robnolimit]

Right you are TubedII. The scrub line gets pretty close when you have a 2" block with 15" wheels. Just remember that the shorter the spring is, the stiffer the truck will feel.

[doublebeetx]

What would be the ideal way then to lower 5 inches and stay with 15 inch wheels ie, best ride and handling ?

[tubbedII]

[QUOTE=robnolimit;4965404]Right you are TubedII.QUOTE]

I'm gonna print and frame this...

[robnolimit]

Originally Posted by doublebeetx

What would be the ideal way then to lower 5 inches and stay with 15 inch wheels ie, best ride and handling ?

I would probably do a 2" block, and 3" spring. But, I'd be risking it with the scrub line. So, is the risk worth the ride quality gain? (vs 1" block and 4" spring) hmm, not sure.

[robnolimit]

[quote=tubbedII;4965720]

Originally Posted by robnolimit

Right you are TubedII.QUOTE]

I'm gonna print and frame this...

thanks, lol

[Greywolf200]

Greetings Rob, did you ever get any results for the raised upper ball joints?

Thanks

[shawnr21]

Great thread!!!, I have some questions that I have not found the answers to yet. Maybe you guys can help. I have a 90 c1500 and would like to get some upper a arms to correct suspension geometry. Does anyone know of any, seems most parts are for the earlier models.

Rob, awesome thread. I would like to get one of your rear 4 bar kits for the same '90 model truck. I'm guessing I can adapt the kit you sell for earlier models to work with my truck. I was wondering how long the bars are that you sell? I recall you mentioning the longer bars or further pivot point is better.

Thanks!!!

[hotrod1]

ROB:

Assuming we are talking about using your 4 link fat bar setup:

I was wondering about rear coil over position. Can it be mounted behind the axle or in front of it, and what would it do to the handling if any? Tilt forward, backwards, further out, further in? How about cantilever like you have in your fat frame?

Any other options?

Thanks

[lolife99]

Originally Posted by doublebeetx

What would be the ideal way then to lower 5 inches and stay with 15 inch wheels ie, best ride and handling ?

I would use a 5" drop spring.

[robnolimit]

Originally Posted by Greywolf200

Greetings Rob, did you ever get any results for the raised upper ball joints?

Thanks

We're finally getting around to putting a set on the JT. It should change the camber gain from .86deg per inch, to 1.23deg per inch. We probably won't test until after SEMA. As a comparison, our wide rides have 1.56deg/in

[robnolimit]

Originally Posted by shawnr21

Great thread!!!, I have some questions that I have not found the answers to yet. Maybe you guys can help. I have a 90 c1500 and would like to get some upper a arms to correct suspension geometry. Does anyone know of any, seems most parts are for the earlier models.

Rob, awesome thread. I would like to get one of your rear 4 bar kits for the same '90 model truck. I'm guessing I can adapt the kit you sell for earlier models to work with my truck. I was wondering how long the bars are that you sell? I recall you mentioning the longer bars or further pivot point is better.

Thanks!!!

We really haven't got into the 88-98's yet, So, I really don't know of any arms that help. But I'll look around. Most of the parts out there are clones of factory arms, or adjusted for lowering, - not for any handling gains. Yes, you can use our FatBar kit, the bars are 30 1/4" eye-eye. The front mounts are slightly modified for that install and must be welded to the chassis.

[robnolimit]

Originally Posted by hotrod1

ROB:

Assuming we are talking about using your 4 link fat bar setup:

I was wondering about rear coil over position. Can it be mounted behind the axle or in front of it, and what would it do to the handling if any? Tilt forward, backwards, further out, further in? How about cantilever like you have in your fat frame?

Any other options?

Thanks

Hmm, let me find some info and picts to post up about cantilever or rocker arm mounting. This may be of interest.

[69gmcc10]

Rob, I am having a difficult time trying to understand how the raised ball joints create an advantage. Can you go into more detail about how these upper ball joints work and are there any disadvantages.

[gringoloco]

Originally Posted by robnolimit

We're finally getting around to putting a set on the JT. It should change the camber gain from .86deg per inch, to 1.23deg per inch. We probably won't test until after SEMA. As a comparison, our wide rides have 1.56deg/in

Would you be able to combine this with an offset upper arm bushing for more gain?

Originally Posted by 69gmcc10

Rob, I am having a difficult time trying to understand how the raised ball joints create an advantage. Can you go into more detail about how these upper ball joints work and are there any disadvantages.

Me too!

[robnolimit]

Tall Ball Joint Geometry

[robnolimit]

Start with the top pict, #1. This is my best wat to show how the camber and Instant Center move, as the suspension is compressed. (outside tire in a turn). The black line is at Ride Height, and shows the position of the Instant Center. When the suspension is compresed (pink lines) note the the angle of the spindle changes - the camber increases. Also, the IC moves in and down.

Pict #2 shows the same base comparison, but with the upper A-arm raised at the ball joint. Because this makes the two ball joints farther apart, the upper arm starts farther up on its arc. And when the suspension compresses the same amount, the spindle lays over a bit farther, giving more camber change. Also, the IC is is in a different place. And although hard to see, it doesn't move as much as before.

Pict #3 is a base graphic of the A-arm arc. Both arcs, yellow and pink, are 20 deg spreads. You can easily see that by starting farther up the arc, the lateral movement is increased. - good for the upper arm, - bad for the lower.

[jayman68]

Originally Posted by 69gmcc10

Rob, I am having a difficult time trying to understand how the raised ball joints create an advantage. Can you go into more detail about how these upper ball joints work and are there any disadvantages.

I was wondering about the advantage also, Thanks for explaining it.

[69gmcc10]

Thank you so much for explaining that! This thread is one of the best parts of this forum! Thanks for sharing your wealth with us, this is the most valuable thread on this forum. Do you sell the raised ball joints?

[robnolimit]

Originally Posted by 69gmcc10

Thank you so much for explaining that! This thread is one of the best parts of this forum! Thanks for sharing your wealth with us, this is the most valuable thread on this forum. Do you sell the raised ball joints?

Thanks a bunch. Just trying to elevate the truck world. Best place to buy is Speedway Motors, Howe Racing, or Stock Car Supply. Ask the techs about them. Howe and Afco also have adjustable (built with a monoball and stud) as well as 'low friction', but these types have a short lifespan - 3 to 5 k miles.

[robnolimit]

Just thought of this. The same gain can be made by lowering the inner pivit shaft for the upper A-arm. This was commonly done in road racing. Known as the 'Shelby mod' on mustangs, or the 'Guldstrand mod' on camaros. They did it by simply drilling new mounting holes a bit lower, and usually a little farther back for more caster.

[Greywolf200]

Back to 1/8" toe out. You said that on JT 1/8" toe out would give better turn in. Is this applicable on other A arm suspensions. The toe at max turn on my 80's Caprice causes a really bad scrub, would 1/8" toe out help here?

Thanks,

[Ackattack]

WOW is all I can say. I read through the 33 pages of post over the last day. WOW.

Where was this thread and wealth of information when I started building my 68, "Bruiser", in 2007. I guess I was ahead of my time applying the pro-touring concept to a truck. I had been reading on pro-touring.com and considered doing a 1st gen camaro, but what can I say, I'm a truck guy. Previous to building my 68 I had read Herb Adams book as well as a few others, and my complaint was that all the suspension stuff for our trucks was geared towards lowering them, not making them handle. I guess times are changing

I guess during my build I never thought too much about modifying what was there (at least too much).

Luckily, after reading through this novel I have gained a lot of insight as to what is now available for our trucks and some ways to modify what we already have. I'm a little slow to this section as of late since my focus lately has been on my other truck and just trying to get it to be a reliable, cool looking daily driver.

At the goodguys show in KC, I thought of taking my truck out to the autocross course, but the brakes need some work. I have tried a few different things with little gain. I think I'm going to clean up the rotors and put new pads on it....hopefully that will solve the problem as I think maybe my pads may have gotten messed up from improper break in, or something.

Based on reading through all of this, it looks like I did some things good (fuel tank in the back, battery in the back, slightly lighter engine (5.3L), rear swaybar (f-body), "OK" shocks) and could probably improve on some things. My biggest complaint about my 68 is that the steering is SO light on the highway just going in a straight line. I assume this is due to having little to no caster. I'll add that to my winter to do list. I'm also going to bite the bullet and move the engine back and lower. I probably have a good 3" from the back of the valve covers to the firewall. Guess I'll have to have a new driveshaft made and make new motor mounts....oh well, it will keep me busy.

Reading over the entire thread I see one common thing. No where does any one mention the "driver mod". Back in college I did a fair amount of autocrossing (LS1 f-bodies) and while its fun to blow money on parts to make you car faster, learning to be a better driver is just as/if not more important than the car itself. For me, other than attending some autocrosses and being in an autocross club where we discussed driving techniques and stuff I haven't really had the chance to do the driver mod. I know there are some course (can't think of the name of them) that will teach you how to be a better driver.

One other thing, on the JT build thread there was mention of using a couple of switches to trick the tranny into staying in gear and keeping the converter locked. Can you go over this a little more? Is it possible to do the same thing (or similar) with tuning? How does it work if, say you spin out and come to a stop with the converter locked up, does the engine stall out?

Again, awesome thread. The sharing of your knowledge and experience is great!

[robnolimit]

Originally Posted by Greywolf200

Back to 1/8" toe out. You said that on JT 1/8" toe out would give better turn in. Is this applicable on other A arm suspensions. The toe at max turn on my 80's Caprice causes a really bad scrub, would 1/8" toe out help here?

Thanks,

My guess is that the Caprice suffers from GM's backwards acreman geometry. So, the outside tire turns sharper (tighter radius) than the inside tire. This is easy to see, just park on level ground, turn the wheels to full lock, and walk about 30 feet in front of the car. Try to position yourself between the paths of the two front tires, kneel down and have a look. The outside tire will be turned in farther than the inside tire. Scrub-scrub-scrub. Try a little toe out, it will help above 20mph, but there is no escaping the scrub in a parking lot at the mall.