lowered 86

[obrut]

I lowered my truck last weekend. Its an 86 GMC C15 and I used belltech 3" drop spindles in the front plus cut one coil and upgraded to the 1.25" brakes at the same time. I did have to grind the front lower control arms to clear the stock 15x8 wheels. I do still get some rubbing when I turn full lock and when I go over a bump. I'm not sure how much I can grind on the control arms, anyone have pictures?

In the rear I used the brackets to flip the axle. I'm still running the stock shocks and I did not put shock extenders on in the rear. I removed the bump stops, the rubber piece and bracket from the frame but the rear seams rough when I go over bumps. Is this because of the shocks?

The front I removed just the bump stop rubber piece but the passenger side seems harsh when I go over a bump.

Would drop shocks help the ride when going over bumps? Should I do shocks or extenders or both?

[obrut]

Its been a while since I lowered my truck, belltech 3" spindle and one coil cut off stock springs with a flip in the rear. I'm running 255 70 15 on factory 15x8 wheels. I did add shock extenders in the rear and new senca-track shocks in the front which help the ride. However my tires seem to rub my wheel wells over bumps and dips.

I'm thinking about changing the front springs out to stock moog 6452 and not cutting any coils. Is there any other springs I should be getting? I do have A/C, V8, dual tank power everything.

[Rich84]

3" spindles, 1.5" drop coils and stock shocks. I never bottom out. Flip with drop shocks in the back.

[obrut]

Rich84 what size tires are you running?

[Rich84]

30x9.5x15..I think drop coils are probably a little stiffer then a 30 year old cut coil.

Just ordered a set of BFG's this morning 255 70 15 which are about an inch shorter.

[obrut]

Ya I think my stock coils are weak and cutting them didn't help. So your current sent up does not rub at all? Do you still have your front bump stops in?

[Rich84]

I only removed the rubber in front.

Cut off the perches in back.

[radar1]

I also recently dropped my 85 GMC. Sounds like nearly the same set up. I did the 3 inch bell tech spindles, and cut one coil on my stock springs. I ended up with a 5 inch drop in front. I also did the flip kit out back. At first I thought that I needed to cut my bump stops on the front. When I did the truck bottomed out badly, actually could hear grinding of the lower a-arm on the pavement. I then replaced the bump stops and cut only about 3/8 of a inch of the second set of bump stops. That helped out a lot. But on occasion I would still rub on the inner fender. I guess I should also tell you that I am running 255/60-15 tires on the front, with 15x7 inch ralleys. The 15x7's have a smaller back spacing than the 15x8's, requiring less grinding of the lower A-arms. I then decided to replace the cut bump stops with new stops, not cutting any at all. That seemed to take care of 90 percent of the rubbing in the inner fender area. All seemed to be great, until I was coming home from a local show. I went over a set of train tracks and caught the leading edge of the A-arms on the concrete in between the tracks, at about 10 mph. The truck stopped right now, killed the motor, and my buddy's glasses ended up under my feet. I limped the truck to the side of the side of the road, and had my wife come to rescue us. Picked truck up next day on rollback. I have since replaced the lower control arms and springs, this time I only cut a 1/2 coil. It raised the truck up near 1 inch. However the crossmember must have been twisted in the accident. The A-arm on the passenger side is touching the header. I am now awaiting the verdict from the body shop, on what it will take on the frame machine to straiten it out.
Pictures are from before I left for the show, and the train tracks that got me. All I can say is be careful with that much drop. It has really sucked this week. I have a build thread going with what I've done to the truck, look for Radar's 85 gmc.

[obrut]

radar1 sorry to hear about your truck, its a nice looking truck. It looks just like mine but mine is red with red interior. My tires are 29" tall which i think is 2" taller overall from yours. I've never hit the frame or control arms I just seem to scuff the wheel wells. I'm ordering the moog 6452 springs tonight and I am going to install them without cutting. I plan to drive it a week and see how I like it and how high it sits. I want to be level with no rake, I'll see how it turns out.

Good luck with your truck

[Rich84]

That's why I am sticking with the taller tires..To keep the lower control arms off the ground.

[rudey737]

That is definitely a horror story, radar1. I'm sorry to hear about your trouble.

I started out with a McGaughy's 4.5/6 drop. I was dumb and didn't rebuild the front end for about 3 months after I lowered it. That meant I didn't shell out some money for an alignment during that 3 months. Bad idea! The bad toe in destroyed my front tires.

So, I put new front tires on it, rebuilt the front end, and got an alignment. Everything was fine, right? Wrong. The front was too low, in my opinion, and rubbed every time I turned right or left. This was with 215/75/15 tires on the front. They are approximately 27.7" tall. I then ordered 1.5" drop springs from Western Chassis and installed them last week. After that, I took the truck in for an alignment. Now everything is perfect. The truck sits almost level - the rear tires are actually 0.5" taller than the front.

I typed all this out for two reasons. The first to let you guys know that dropping these isn't an exact science. There are so many variables that, even had I done everything at once, I still would have ended up replacing the 2" springs with 1.5" springs. The second is that I wouldn't go much smaller in my front tires than I already have. Like Rich84 said, you can get too close to the ground with smaller tires and start running into issues with the scrub line of the truck.

[50seven]

I agree these trucks need a certain diameter of tire just to fill out the wheelwells to give it the right look. Too small of a tire just looks wrong IMO.

Find some stock Van Rallys for the front they came in 6 & 7 inch widths and I do believe had a few different offsets. Pbbly find them with tires already on them cheap....give you a chance to check your clearances before buying new rubber.

Your local tire shop could probably source new rallys in a whole bunch of different sizes & offsets also. I bought new steel rims for a Jeep it was around $80 each any size/offset I wanted.

[obrut]

I changed the springs this weekend, after a short drive I came back and measured 30" from the ground to the wheel well trim. It was 27 1/2" with the old springs, so the new springs raised it 2 1/2".

The truck is now level when measuring off the bottom of the cab and bed but because of the different wheel well opening front to rear it looks like the front is higher.

I'm going to drive it for two weeks, see where the springs settle at and then pull them and cut 1/2 a coil if I need to. I would like to get the front about 1 to 1 1/2" lower from where it is now. I think my old springs where just weak because the new springs don't bounce as much as the old ones.

[Rich84]

It will settle..Be patient with it. I think it might take a little longer then a couple of weeks..

[Keith Seymore]

Originally Posted by radar1

All seemed to be great, until I was coming home from a local show. I went over a set of train tracks and caught the leading edge of the A-arms on the concrete in between the tracks, at about 10 mph. The truck stopped right now, killed the motor, and my buddy's glasses ended up under my feet. I limped the truck to the side of the side of the road, and had my wife come to rescue us. Picked truck up next day on rollback. I have since replaced the lower control arms and springs, this time I only cut a 1/2 coil. It raised the truck up near 1 inch. However the crossmember must have been twisted in the accident. The A-arm on the passenger side is touching the header. I am now awaiting the verdict from the body shop, on what it will take on the frame machine to straiten it out.
Pictures are from before I left for the show, and the train tracks that got me. All I can say is be careful with that much drop. It has really sucked this week. I have a build thread going with what I've done to the truck, look for Radar's 85 gmc.

We run a product assurance test looking for this type of condition. The specific test is called "the Dayton Railroad Crossing", named as a result of an incident that occured 50 or 60 years ago.

Many passenger cars will have a "skid" as part of the front engine crossmember in an attempt to keep the chassis from hooking on the railroad tracks. My '74 Chevelle did.

K

[obrut]

Originally Posted by Keith Seymore

We run a product assurance test looking for this type of condition. The specific test is called "the Dayton Railroad Crossing", named as a result of an incident that occured 50 or 60 years ago.

Many passenger cars will have a "skid" as part of the front engine crossmember in an attempt to keep the chassis from hooking on the railroad tracks. My '74 Chevelle did.

K

How would you conduct the test? What was the incident - i can guess as to what happened but what were the details.

[Keith Seymore]

The Milford Proving Grounds has "the world's shortest railroad" (ie, two railroad crossings with tracks that extend just a few feet either side of the road) as part of the Ride & Handling loop.

The subject vehicle is run repeatedly a set of predetermined speeds to see if the Dayton incident can be duplicated.

I don't recall any details about the original incident beyond that it happened and created this test procedure.

K

[obrut]

Keith thats cool, I love hearing about the different testing and inside stuff from back in the day that GM would do.

I've been driving my truck everyday and have not had one problem except the front is too high. I really think I need to pull the springs and cut half a coil to get the front end down a little. I'll let another week or two go by and see where its at.

radar1 any news on your truck?

[radar1]

I got my truck back from the local body shop last Friday. They determined that I rolled the front crossmember about a inch to a inch and a half. They were able to pull it back into position, at least now the lower control arms, where they mount to the frame section is level. When I put the replacement lower control arms on I put a different set of springs in. This set is a original set that I cut off one half of a coil. Hoping to raise it up a inch, thinking that I may miss the rails this time. I have found with the half coil cut springs that the one on the left side seems to be ok. The spring on the right side isn't fitting so well. When I cut the springs I cut the bottom coil, just as I did on the previous spring. When installing the springs I located the cut end in the notch on the lower control arm, but am having trouble with the top end of the spring. It appears that the upper locating piece is not just round, more of a rounded triangular shape. I cant seem to get the spring to set properly in the upper locating mount. It is causing the spring to bow, which in turn causing it to rub on the crossmember. I am thinking now that if you wanted to cut a original spring one coil, that is fine. but to try to cut a half a coil causes the spring alignment to be off. I could be wrong. I actually removed the spring and turned it to align with the upper locating piece, and the spring straightend out. But it raised the truck back up nearly two inches. Right now I can live with what I got, but I am planning on ordering a set of one inch lowering springs. I figure they will have the tails of the spring in the appropriate places. My initial drop was like, right at five inches in the front and five and three quarters in the rear. Now I am four inches in the front and the rear hasn't changed. Driving now feels better, I am hardly ever rubbing the inner fender well. Even though I still feel squeamish when I go over the local train tracks. By the way I am still running the full rubber bump stops on the front control arms, and we completely removed the rear bump stops from the rear axle.

[radar1]

This is one of the latest pictures. Hauling home the new refrigerator. The right front is just over a inch higher than the previous pictures

[obrut]

radar1 glad to see your truck on the road again.

When I installed the new springs I noticed the same thing about the upper spring only fitting one way because of the way the metal is formed. I didn't think much about it until you said it in your post. Thinking about how the spring fits it doesn't seem like I can cut just half a coil.

[Lost81c10]

I did the same with my lowering spring on one side "temporarily" (about a year ago waiting to get some new leaf springs to level out my lean). i cut about 2 inches of the first bottom coil on the high side (i also added some shims under the leaf springs to the low side because i did not want my front much lower once i got new leafs). I have not noticed anything wrong or felt any bad effects of the bottom end of the cut spring not sitting on the lower control arm slot. Hopefully it will be ok in the longer run.

Mando

[obrut]

I going to cut half a coil this weekend to try and get the front down 1" I'm still not sure if cutting half will work because of the way the upper fits in the pocket, anyone have experience with this?

[obrut]

I did a little more searching and a couple posted I read said to cut 1/2 a coil off the bottom of the spring. Then line up the top of the coil into the D shape in the upper spring pocket and leave the bottom where ever it lands, does that sound right?

[obrut]

Just got done cutting a half coil and it only lowered the truck about 1/2". I lined the top of the spring up in the pocket so the bottom end of the spring was by the ball joint 180 degrees opposite from where it normally is. I'm now at 29 1/2" tall I was looking for 28 1/2 to 29"

Should I rotate the spring 180 degrees so the bottom pigtail is in the groove like stock? Will the top "locate" like it should?