Lowering for Maximum Ground Clearance

[Cris]

I keep going over my truck suspension looking on how to lower it while still preserving as much ground clearance as possible. Right now, I have 2" lowering springs on stock spindles. The lowest point on the front suspension are the lower a-arms. (They sit lower than the cross member.) Adding drop spindles would not change this condition, the lower a-arms remain in the same position. At this point, a shorter spring would make sense to tuck the lower a-arms up further in the frame.

I understand that lowering the front suspension using only springs starts to hurt the suspension geometry, but it does seem to be the best path for clearance, at least to the point where the lower a-arm is "tucked up" and even with the cross member.

In the rear, lowering with springs again gives you the most clearance. Adding blocks lowers the truck, but reduces ground clearance at the trailing (truck) arms.

Thought I would get your ideas before I start hacking on my springs.....

[theastronaut]

Depending on how low you want to end up, the crossmember/A-arm bushings will be the lowest point. They hang 1.5-2" lower than the frame rails under the cab. There are aftermarket arms like CPP or Porterbuilt that have slightly smaller bushings that don't hang quite as low. You can also pancake the crossmember to increase ground clearance, or notch the frame about the crossmember to raise the whole crossmember. I notched the frame 1.5" on my gold '66 to get the bottom of the crossmember level with the bottom of the frame rails under the cab.

On my blue '66 I ran stock springs with 1.5 coils cut off for about a 3" drop, and 2.5" spindles. The crossmember was less than 3" off the ground, and I only had about 1.5" of clearance between the inner fender and top of the tire with 215/75-15's. The tires would rub the inner fenders over larger bumps, and the crossmember would occasionaly scrape over huge bumps. Shorter tires would have lost ground clearance at the crossmember, so it needed to be raised up about an inch with taller springs.

[Cris]

theastronaut:

Thanks for the info. With the 2" lowering springs, my cross member is still 9" off the ground. So I'm a long way off from as low as you have gone on your trucks! The lowest part of the a-arms are 7 1/2" off the ground. Below is a shot of how my a-arms sit right now.

I'm hoping to cut the springs and lower the truck another 3 1/2" without resorting to drop spindles. That would leave me with 5 1/2" of crossmember clearance and the a-arms should move up out of the way. I'll still have to deal with the bump stops and steering stops getting in the way though. Do people cut off the steering stops on the a-arms for clearance when lowering?

Thanks, Cris

[hewittca]

If I'm reading this correctly, you want to get a total of 5.5 inches of drop out of just the springs by cutting drop springs? That's too much drop with just springs up front. I have a 4" spring drop on my truck and I had to make quite a few tweaks to the suspension to get it to handle correctly. I briefly tried going to a 5" spring drop with a spare set of springs I had and the truck rode terribly. Also, my balljoints were binding up. I really would advise against going that low with springs.

Plus, I don't think it's really going to achieve what you are looking for in terms of control arm clearance. The mounting point of the lower arm is still going to drop the full amount of the spring drop. The ball joint end of the arm is in a fixed position in relation to the wheel so that's not going to change in regards to clearance, so what happens is you level out the control arm around the pivot point of the ball joint which puts the whole arm closer to the ground. I think if you want to go really low, you just have to accept that you will have low ground clearance. If you wanted to go all out, you could pancake the crossmember or notch the frame to raise the crossmember up. Both of these options would raise your suspension in relation to the frame while leaving the same suspension ground clearance.

[forestb]

I have 2 inch drop coils and 2 inch drop spindles and the only thing that hits the ground on my truck is the front bumper when I go over speed bumps to fast

[Cris]

hewittca:

Thanks, good information on how much I can drop with springs alone. I think my next step will be to reassemble the front suspension with no springs and then run it through a full range of motion while on the lift. I should be able to reproduce any of the issues.

I understand what you are saying in that I can't really increase the ground clearance to the a-arm. But my crossmember is well above my a-arm, so I can lower the truck (until the crossmember is level with the a-arms) and (at least) pay no penalty in overall clearance.

I think you are right in that 5" is probably too far to go on springs alone.....

[Cris]

forestb:

Thanks for the info. If you get a chance, how much clearance to your crossmember?

Thanks, Cris

[PGSigns]

There are a couple of things you need to think about with a lot of spring drop and the biggest one is going to be bump steer. It matters little how you are lowering the truck as the result is for every inch you drop it the cross member is going down an inch. No way to go lower with out that happening. If you are going to pull the springs and run it through the travel do it on an alignment machine and look at the bump steer and camber gain. Camber gain is just hard on tires but bump steer can get down right scarry at times. 2" springs and 2 1/2" spindles will get you down there with out making it no fun to drive.
Jimmy
Jimmy

[Cris]

Jimmy:

I'll look at bump steer. I can see the tie rods are going to be at a pretty steep angle so bump steer has been on my mind. Do you know of anyone that has used a different steering arm on the spindle to relocate the tie rod location? It almost looks like they could be flipped over (right side would go to left side and left to right). I've used adjustable blocks on steering arms to tune the bump steer, not sure if anything is made or could be adapted for the C10 arms.

Thanks, Cris

[PGSigns]

No good way to flip the tie rods. You still have to deal ball joint bind, and all the alignment issues that the steep tie rods cause. So why not drop spindles? You started the thread looking for ways to improve the ground clearance and the way you want to drop the truck does nothing to improve that. It just compromises the steering and control of the truck. If you really want to run the stuff you have and get the truck down it is time to look into pancaking the crossmember. I run 2" springs and 2 1/2" drop spindles with 225-70-15 tires and it is my daily driver with 40,000 miles in this setup with no issues.
Jimmy

[hewittca]

Bumpsteer definitely is one of the important things to consider when going low. I do believe that I have seen a few guys have success with flipping the outside tierod. In fact, I've done it on a past project and plan to do it on my truck once I add drop spindles. On my past project, all I did was ream out the hole half way through on the bottom with a tapered ream. It does leave the hole in an hourglass shape and you only get half the width retention on the tierod end, but I never had any problem with it. Of course, one example isn't enough to prove this is the best way to do it, but it was a common mod on that type of vehicle and I never saw anyone have an issue. If it worries you, there are sleeves you can put in that will give you full retention. Anyway, if you do flip the tierod it gets it close to level again.

[Cris]

I'm not ruling out drop spindles. I just wanted to see what the issues were with a drop by springs alone. If I could just put new spindles in, I would go that route. But drop spindles require you to switch to disc brakes, new master, brake lines, proportioning valve, etc, etc........I really wish someone would make drop spindles for drum brakes!

I pulled the springs last night and ran the suspension through its full range of motion. The most questionable spot is the lower ball joint. It gets to a pretty steep angle with 5" of drop.

Even with a 5" drop, I still would have 6" of clearance to the cross member. I don't want to lay frame, just get the truck down a little.

Any other thoughts appreciated. I know guys used to lower without drop spindles, but I don't know all the tricks they used.

[hewittca]

I'm right there with ya! I really wish someone would make drop drum spindles too. I only cruise my truck on the weekend for fun and my rebuilt drum brakes get the job done adequately. Just wish I had a few more inches of drop...

Looks like you saw what I did with that lower ball joint at 5 inches. Any suspension travel at all past that point and the balljoint is seriously compromised.

One old school option is stepped lower arms. Basically you cut the ball joint mounting location off the end of the lower control arm and fab up a bracket to move it up a few inches. The top arm you leave alone. It acts like a drop spindle in that it moves the wheel up in relation to the suspension but leaves the suspension geometry unchanged. Of course, your tierod moves up as well so you still have to consider flipping that. Here's a thread about how one guy built his.

[Cris]

hewittca:

Thanks. Very informative link. We do need drop spindles for drums. The other thing the disk brakes will force me to do is replace my stock wheels. Getting expensive to drop my truck....

On another forum someone mentioned extended ball joints. The stock car crowd uses them to adjust suspension geometry. I don't think you could go that far with them, but its worth looking into.

CPP spindles look like the best choice for dropped spindles. They seem to have the least impact on track width. Other manufacturers drop spindles will increase track width over a drum brake set-up.

It ain't ever easy.

[hewittca]

Yep, the stock wheels on a drum truck won't fit over the disk brakes. That's the only reason I got new wheels for my truck because I really liked my old 15x8 steel wheels. I like my new wheels too and was going to get them eventually, but I had originally planned on dropping that $ on the disk/spindle kit which is why I still don't have the drop spindles.

I've heard of the extended balljoints too but haven't seen anyone use them on these trucks. Like you said, I doubt you could get them long enough to make any real noticeable difference.

I've been tossing between the CPP kit and the ECE kit. With the CPP modular spindles, it would be nice to retain original track width but then you have to go a different route with the brakes. The modular spindles are made for big brake kits. If you want to use the stock style disk brakes, you have to get adapter brackets to work with those modular spindles. I like the ECE kit for quality and completeness. It has everything you need to do the conversion whereas the CPP kit is missing a few key things like master cylinder, proportioning valve, and brake line adapters. Plus ECE has a much better reputation than CPP.

[forestb]

If you get the CPP modular spindles you will not be able to use a 15 inch wheel.

Just a thought but if your truck hits a bump big enough to bottom out on the lower control arm it would seem that they would rise up enough for you to be hitting the cross member anyway.

[Cris]

I did a pretty extensive internet search yesterday on the CPP drop spindles. They make two types, the modular and their OE version. The OE version has a narrow track width like the modular. The modular uses a bracket to mount the brakes, the OE includes the caliper brackets in the casting. Here's a link to a discussion on CPP spindles and their track width including a spreadsheet with a listing of track widths.

http://67-72chevytrucks.com/vboard/s....php?p=5434129

I believe you can run standard brakes on the modular, you just buy the correct bracket. The advantage of the modular over the OE is you can buy different brackets to run big brakes. With the OE you are stuck with the stock disc brake calipers.

I haven't dealt with CPP yet, but they don't have the greatest rep on this forum. The guys at ECE are really responsive and know their parts.