1968 c10 prostreet suspension attention

[71chevswb]

I've got a 1968 c10 shortbed 6 lug truck that is in need of some serious suspension attention. Above 60mph it shakes pretty good. It's got a 454 BBC (~500 HP), wide rear tires (18") and its Tubbed about 5".

It's currently rolling on drop springs, lowering block in the rear (1"), and some drop a-arms up front. Putting it at about a 5/7 drop. It rides like crap but has a decent stance. The shocks are still mounted to the factory location and have a steep angles. So I need a rear track bar relocation setup and shock relocators too.

When I go to upgrade the brakes this winter what suspension set up would you do? Budget is a factor!

Should I stick with a static/spring drop? ECE? I don't really want it any higher than it is, thinking an ECE 4/6 drop isn't low enough?!

I'm considering bagging it but between the full exhaust and wide tires, I'm not sure how much lower it can go. Also, are bags a bad idea with that much horsepower?


Let me know what you would do. Thanks!
Posted via Mobile Device

[68Stepbed]

A vibration above 60 mph shouldn't be a suspension issue. I suggest making sure the tires are balanced and the wheels are true. I've seen lots of those aftermarket rallies being warped even when new. Also, make sure your alignment is all in spec.

I'm going to assume you have drop spindles in the front along with drop springs.

[71chevswb]

I have drop springs in the front and drop a-arms. I don't think they are drop spindles. I just got the tires and wheels rebalanced. I'll have to try alignment next.

[chevy_mike]

Remember, a tire/wheel can balance okay but can still be bent, have runout or be somewhat oval. I had a wheel that would balance perfectly but when we check the side runout, we found it was bent. Had to replace the wheel to fix the issue.

[68Stepbed]

The reason I ask about spindles is if the front springs are too short, they can cause issues. There's really hardly any pressure on the springs in these trucks. They almost fall out when load is taken off of them. The shorter they are, the worse. If the front drop is mostly drop spring, or cut stock springs, it's not keeping adequate pressure in the spring pocket and keeping the front wheels/tires from keeping constant contact with the road.

Also, like chevy_mike said, balanced wheels/tires doesn't mean the wheels are true.

You might also want to make sure the driveshaft is correctly balanced.


We don't mean to burst your bubble or make out like we're picking on you or your truck. I personally hate to see you spend lots of money for new suspension and still have the same problem. Better to diagnose and fix the right problem than to start throwing money at it hoping it fixes it.

[71chevswb]

I appreciate the suggestions guys! The springs are too short in the front. You jack the truck up in the air in the front and you can hear the spring pop in and out of place. The drivers side spring isn't up against its stop, the coil is twisted.
Would this cause a "shake" or vibration?

I would hope the driveshaft is ok because it's a newer, custom fit driveshaft. But the vibration does seem harmonious.

[Overdriven]

Wheel/tire balance is the obvious first thing to check as others said. While they're on the balancer they can check runout as well. If the driveshaft is fairly new and you know that no weights have fallen off then you should check the pinion angle of the rear. Guys often flip the trailing arm mounts to help correct the pinion angle when going past about 5" of drop in the rear. Also check and see if your tires are rubbing since you said you're running the stock track bar. My truck is bagged on stock suspension (previous owner did it) and the tires rub when lowered too much. I don't have to worry about it too much because I can tell when it's too low by the ride being really bad from hitting the factory bump stops.

I didn't know there were any drop a-arms available for our trucks, can you tell us who makes them? Of course there's aftermarket arms that help correct geometry on dropped trucks but I didn't know of any that actually lowered the truck as well. The only way I can figure an arm could lower a vehicle is by lowering the spring pocket in the arm or raising the ball joint mounting locations. Lowering the spring pocket would have the same effect as drop springs and combining the two would severely limit travel. This is why drop spindles are so popular, they don't effect travel and ride quality like drop springs do.

As far as ride, let's get a clearer picture. Is the frame c notched in the rear? Stock bump stops? How far are you from the bump stops and/or frame at ride height? If you have like 2" or less then it's going to ride bad because it's going to be hitting the bump stops. The cure is c notch the frame with aftermarket bump stops mounted to the side of the frame. Then shock relocation brackets to straighten them out.

The story is basically the same up front, see how far you are from the bump stops at ride height. If you're too close to them the truck will be hitting them making for a bad ride and you'll have some decisions to make.

[71chevswb]

DJM tubular lower a arms. The spring pocket is dropped/lowered. C-notched in the rear. I haven't checked the bump stops and have no idea on that.

My plan is to ditch the Lower a arms, relocate the rear shocks and pan hard bar. Switch to drop spindles. I don't even remember if it's got a sway bar up front, I'm sure it has to. If it doesn't have one, I'll add one. I also want to rebuild the front end while its apart. Bushings and what not.

I've got a brand new 4/6 ECE kit laying in the corner of the shop, I bought it for my 71. Thinking about using that, but wondering if it will work on my 68. What isn't interchangeable on the front end of a 71 versus a 68? I know the 71 is factory front discs and 5 lug versus the 68 6 lug and drums.
Posted via Mobile Device

[andrewmp6]

The shake you have is it from the front or rear of the truck.Does it go away if you go faster ?And have you tried pulling it out of gear when it shakes to see if its driveline or suspension?

[Overdriven]

71-72 uses different balljoints and outer tie rods. The balljoints and outer tie rods must match the spindles you are using. So if you bought 71-72 balljoints and outer tie rods you could use the 71-72 spindles in your 67-70 truck. But if the 71-72 ECE kit you have is 5lug then you'd need new wheels too. There are 6 lug disc kits for 67-70 that would allow you to keep your wheels. Price it out both ways, I'm not sure which is more budget friendly.

[71chevswb]

So if I bought an ECE 6 lug disc conversion kit, it comes with 2.5" drop spindles for a 67-70. Then I could use my new 4/6 ECE kit? I was planning on buying that disc conversion kit anyways, or one similar to it.
Posted via Mobile Device

[71chevswb]

Originally Posted by andrewmp6

The shake you have is it from the front or rear of the truck.Does it go away if you go faster ?And have you tried pulling it out of gear when it shakes to see if its driveline or suspension?

The driveline still spins when you pull it out of gear. How would that tell me if its the driveline or suspension?!
Posted via Mobile Device

[68Stepbed]

Originally Posted by 71chevswb

DJM tubular lower a arms. The spring pocket is dropped/lowered. C-notched in the rear. I haven't checked the bump stops and have no idea on that.

My plan is to ditch the Lower a arms, relocate the rear shocks and pan hard bar. Switch to drop spindles. I don't even remember if it's got a sway bar up front, I'm sure it has to. If it doesn't have one, I'll add one. I also want to rebuild the front end while its apart. Bushings and what not.

I've got a brand new 4/6 ECE kit laying in the corner of the shop, I bought it for my 71. Thinking about using that, but wondering if it will work on my 68. What isn't interchangeable on the front end of a 71 versus a 68? I know the 71 is factory front discs and 5 lug versus the 68 6 lug and drums.
Posted via Mobile Device

Originally Posted by 71chevswb

So if I bought an ECE 6 lug disc conversion kit, it comes with 2.5" drop spindles for a 67-70. Then I could use my new 4/6 ECE kit? I was planning on buying that disc conversion kit anyways, or one similar to it.
Posted via Mobile Device

Since you plan to rebuild everything anyway, just install 71-72 ball joints, tie rods, and drag link and use what you have in the corner.

One more question, is the vibration felt through the whole truck, or through the steering wheel?

[71chevswb]

Originally Posted by 68Stepbed

Since you plan to rebuild everything anyway, just install 71-72 ball joints, tie rods, and drag link and use what you have in the corner.

One more question, is the vibration felt through the whole truck, or through the steering wheel?

vibration is through the whole truck.

Using 71-72 parts all around means I would have to use 71-72 discs and therefore make it 5 lug?

[71chevswb]

does anybody know if ECE's disc brake conversion kit would work with my 15" rallies? What about a set of 15x8 4 nub steelies I have?

Im trying to consider my future wheel choices while deciding which direction to go with the suspension.

[Overdriven]

Originally Posted by 71chevswb

does anybody know if ECE's disc brake conversion kit would work with my 15" rallies? What about a set of 15x8 4 nub steelies I have?

Im trying to consider my future wheel choices while deciding which direction to go with the suspension.

I could be wrong but I'm pretty sure all the disc conversion kits out there use 73-87 brake parts. Seen plenty of those trucks with 15" Rallys on them.

I'm in the same boat as you actually with my 67 6 lug, deciding the future with this winters suspension rebuild and disc upgrade. I'm on stock wheels so it's pretty easy for me to say screw it and make the switch to 5lug though. Your truck looks damn cool the way it is, would be harder for me to change it up.

I'd try emailing ECE or McGaughy's, maybe they can put something together for you to use as much of what you have as possible. For example if you can save a few bucks just getting 6 lug rotors, calipers, tie rods, etc and put it on the ECE 71-72 kit you have. I'd check to make sure it's possible but I'd think it would be. They'd also be able to tell you about wheel fitment, possibly email you a template to print out or at least a diagram with critical measurements.

[68Stepbed]

Originally Posted by 71chevswb

vibration is through the whole truck.

Using 71-72 parts all around means I would have to use 71-72 discs and therefore make it 5 lug?

You could order the 6-lug front rotors from ECE, but everything else would be 71-72 parts.

Vibration through the whole truck leads me to look more to driveline vibration or out of round wheels.

[71chevswb]

Originally Posted by Overdriven

I could be wrong but I'm pretty sure all the disc conversion kits out there use 73-87 brake parts. Seen plenty of those trucks with 15" Rallys on them.

I'm in the same boat as you actually with my 67 6 lug, deciding the future with this winters suspension rebuild and disc upgrade. I'm on stock wheels so it's pretty easy for me to say screw it and make the switch to 5lug though. Your truck looks damn cool the way it is, would be harder for me to change it up.

I'd try emailing ECE or McGaughy's, maybe they can put something together for you to use as much of what you have as possible. For example if you can save a few bucks just getting 6 lug rotors, calipers, tie rods, etc and put it on the ECE 71-72 kit you have. I'd check to make sure it's possible but I'd think it would be. They'd also be able to tell you about wheel fitment, possibly email you a template to print out or at least a diagram with critical measurements.

I like the way you think! I'll try that. I'm worried about the 15x8 steelies I have because ECE states that stock wheels might not work with the disc kit. And I don't see why my rallies would be any different than those steelies.

Thanks for the suggestions!
Posted via Mobile Device

[71chevswb]

Originally Posted by 68Stepbed

You could order the 6-lug front rotors from ECE, but everything else would be 71-72 parts.

Vibration through the whole truck leads me to look more to driveline vibration or out of round wheels.

I'm thinking driveline too because it's harmonious and it seems to vibration through out. What's the best way to check the driveline? Take it out and go to a driveline shop?


I can't see a reason for the wheels being out of round. I think they are wheel vintques, large wheel markers.


Posted via Mobile Device

[Overdriven]

Originally Posted by 71chevswb

I like the way you think! I'll try that. I'm worried about the 15x8 steelies I have because ECE states that stock wheels might not work with the disc kit. And I don't see why my rallies would be any different than those steelies.

Thanks for the suggestions!
Posted via Mobile Device

Well 67-70 3 nub steelies can't be used with disc brakes because of the profile of the wheel center. 4 nub steelies came on later disc brake trucks and guys have been using them for that reason. I've read that some stock steel wheels (besides 3 nub) won't fit some disc setups as well.

[72c105speed]

How's the driveshaft and u joints look?

[71chevswb]

Originally Posted by 72c105speed

How's the driveshaft and u joints look?

New driveshaft, not sure on u joint. Probably stocker.
Posted via Mobile Device

[71chevswb]

Originally Posted by Overdriven

Well 67-70 3 nub steelies can't be used with disc brakes because of the profile of the wheel center. 4 nub steelies came on later disc brake trucks and guys have been using them for that reason. I've read that some stock steel wheels (besides 3 nub) won't fit some disc setups as well.

Mine are 4 nubs. I've heard the same thing
Posted via Mobile Device
Posted via Mobile Device

[andrewmp6]

Originally Posted by 71chevswb

The driveline still spins when you pull it out of gear. How would that tell me if its the driveline or suspension?!
Posted via Mobile Device

Yes the driveline is still spinning but its no longer under the load it was when you pull it out of gear rolling.If you pull it out of gear and the shake stops then its driveline related.Can you pin point where the shake is from the front or the rear or the truck?Does the steering wheel shake or not.

[Robznob11]

With that drop, i would put an angle finder on the tail shat, drive shaft, and pinion and see what you have. You are at the point where your rear may be higher than the center line of the crank. When this happens even tho the angles on tranny and pinion look right the driveshaft running up hill towards the rear can caus your actual yoke angle to be out side of the operating range of the yoke. Then you have to play with both ends of the driveline to make everything happy. Like shimming the tranny up some. I had to do this on mine.