Front Coil Spring Clearance Problem

[JohnIL]

I've run into a weird clearance problem on my '65 C10. See the pictures below for a visual explanation.

Here's the scenario.

When I bought the truck, the PO had installed a set of LMC 2" drop coils on the front. Occasionally, whenever I unloaded the front suspension over uneven ground, I would hear one of the front springs twang. I assumed it was just because the springs are shorter than the originals.

Fast forward to today. I'm approaching the end of a power brake conversion project. While I had the front suspension apart, I did the common caster correction mod. I moved the lower control arms 3/4" forward to add more caster. As you would expect, this mod adds a minor angle to the springs. I had the truck back on the street for the first time tonight and the driver side front spring twangs every time I hit a pebble. With the truck back up on blocks, it's clear that the driver side front spring is making contact with the front edge of the upper spring pocket. The passenger side spring, however, is nicely centered in the upper spring cup, with about 3/8" of clearance.

You can see the difference in the pictures below. The first picture is the passenger side spring with plenty of clearance. The second picture is the driver side spring, clearly making contact with the front edge of the spring pocket. I verified that both springs are centered in the upper spring pocket and lower spring cup. I verified that that ends of the coils are seated in the indentions the lower spring cups. As far as I can tell, the springs are properly seated.

I thought maybe the driver side lower control arm might be further forward than the passenger side. I measured the position of the control arms from fixed points on the frame rails. They measure exactly the same.

So, I'm stumped. I would expect the springs to vary a little bit from side to side, but this seems pretty extreme. Is it possible the springs are that much different from each other?

I appreciate any wisdom you can share.

John

[Richard]

Originally Posted by JohnIL

I've run into a weird clearance problem on my '65 C10. See the pictures below for a visual explanation.

Here's the scenario.

When I bought the truck, the PO had installed a set of LMC 2" drop coils on the front. Occasionally, whenever I unloaded the front suspension over uneven ground, I would hear one of the front springs twang. I assumed it was just because the springs are shorter than the originals.

Fast forward to today. I'm approaching the end of a power brake conversion project. While I had the front suspension apart, I did the common caster correction mod. I moved the lower control arms 3/4" forward to add more caster. As you would expect, this mod adds a minor angle to the springs. I had the truck back on the street for the first time tonight and the driver side front spring twangs every time I hit a pebble. With the truck back up on blocks, it's clear that the driver side front spring is making contact with the front edge of the upper spring pocket. The passenger side spring, however, is nicely centered in the upper spring cup, with about 3/8" of clearance.

You can see the difference in the pictures below. The first picture is the passenger side spring with plenty of clearance. The second picture is the driver side spring, clearly making contact with the front edge of the spring pocket. I verified that both springs are centered in the upper spring pocket and lower spring cup. I verified that that ends of the coils are seated in the indentions the lower spring cups. As far as I can tell, the springs are properly seated.

I thought maybe the driver side lower control arm might be further forward than the passenger side. I measured the position of the control arms from fixed points on the frame rails. They measure exactly the same.

So, I'm stumped. I would expect the springs to vary a little bit from side to side, but this seems pretty extreme. Is it possible the springs are that much different from each other?

I appreciate any wisdom you can share.

John

Reading this it seems like you measured to the frame mounting point on the arms. Springs are further out to wheels than that. Maybe measure to outer point on arms like center of ball joints and see if the same on both sides. Maybe something crazy like two passenger side lower arms installed?

[JohnIL]

Originally Posted by Richard

Reading this it seems like you measured to the frame mounting point on the arms. Springs are further out to wheels than that. Maybe measure to outer point on arms like center of ball joints and see if the same on both sides. Maybe something crazy like two passenger side lower arms installed?

Richard,
Thanks for the idea. I measured from fixed points on the frame to the lower ball joints. Both sides are the same. And, the shock mounts are on the rear side of both control arms.

The difference appears to be in the springs themselves. Any other ideas?

Thanks.
John

[leegreen]

Are tops of springs fully seated over the centering ring?
Is compressed spring length same both sides?

What parts did you change, just spindles? Ball joints fully seated in CA and spindle? lower CA bushings in good shape and shafts still straight? Holes in cross member for lower CA still nice and round?
maybe some old collision damage - Flanges at ends of crossmember still parallel to each other? CA themselves bent?

Or a bad spring

[JohnIL]

Lee,
Thanks for the feedback. I checked most of this already, but you've given me a few more things to measure.

The springs are definitely fully seated. This was my first thought. I checked the tops and bottoms multiple times.

I replaced the spindles, ball joints, lower control arm shafts, and bushings. The ball joints are fully seated. I checked that last night too. I measured the control arm shafts to verify their the same from one side to the other.

It's difficult to confirm the control arms are straight, but they do measure the same to fixed points on the frame. If there is a difference between the left and right lower control arms, it is in the 1/16" neighborhood.

I haven't measured the compressed spring height and the crossmember flanges. But, I definitely will.

Thank you for the leads.

John

Originally Posted by leegreen

Are tops of springs fully seated over the centering ring?
Is compressed spring length same both sides?

What parts did you change, just spindles? Ball joints fully seated in CA and spindle? lower CA bushings in good shape and shafts still straight? Holes in cross member for lower CA still nice and round?
maybe some old collision damage - Flanges at ends of crossmember still parallel to each other? CA themselves bent?

Or a bad spring

[JohnIL]

I'm thinking about swapping the springs from one side to the other to see if the problem follows the spring or it stays on the driver side. Before I commit to all that work (disconnecting the ball joints and shocks to release the springs), I'd like some feedback. Does this make sense or am I just wasting time?

Thanks.
John

[Richard]

Originally Posted by JohnIL

Richard,
Thanks for the idea. I measured from fixed points on the frame to the lower ball joints. Both sides are the same. And, the shock mounts are on the rear side of both control arms.

The difference appears to be in the springs themselves. Any other ideas?

Thanks.
John

The difference at the ball joints may be able to be compensated for with an alignment. Next I would measure to a point on the spring pockets in lower arms.

[JohnIL]

You make a good point about alignment adjustments. I measured from a fixed point to each of the drainage holes in the bottom of each spring pocket. Assuming the holes are stamped the same on both control arms, they measure the same. I will take more careful measurements tonight.

It's almost like the spring sits differently in the pocket on the right side than it does on the left side. I know that's partially true, because both springs are wound the same direction and both lower spring pockets both "index" toward the center of the truck. The lower tails of both springs are on the inside (center side) of the spring pocket. That puts the upper tails on opposite sides from each other. The upper tail on one side faces the front of the vehicle. The upper tail on the other side faces the rear of the vehicle. But, if this were the problem, then every one of our trucks would have the same problem.

Originally Posted by Richard

The difference at the ball joints may be able to be compensated for with an alignment. Next I would measure to a point on the spring pockets in lower arms.

[JohnIL]

UPDATE: I found the culprit!

I know exactly why the driver side spring is making contact with the spring pocket. But, I don't know what to do about. The problem is in the upper spring pockets themselves.

I dropped the lower control arms on both sides and removed the springs. Both springs are identical. Same part #,same uncompressed height, same diameter, and they are both coiled the same direction. With the springs out the way, I could get a better look at the upper spring pockets. The alignment hole in the driver side pocket is almost a full inch further forward than the passenger side.

Take a look at the pictures below. In both pictures, I'm measuring from the alignment hole to the back of the spring pocket. The left picture is the driver side. The alignment hole measures 2 7/8" inches forward from the back of the spring pocket. The right picture is the passenger side. That alignment hole measures only 1 7/8" forward from the back of the spring pocket.

Is this normal? The aftermarket springs were already installed when I bought the truck. I've never seen the original factory springs. I'm wondering, if the original springs where different from one side to the other?

Any thoughts on how to deal with this to correct the spring alignment?

Thanks.
John

[leegreen]

The different offset of the upper spring pocket appears to be normal.

this is a ~ 81 squarebody cross member and the pockets are offset, Drivers is further forward. I marked the picture in red where the ends of these upper pockets are



Maybe it matters more that the upper, tapered end of the spring sits in the pocket, is that what you have now?

[JohnIL]

Lee,
Thanks for posting the picture. It's good to know I don't have some sort of mutant front cross member. I was beginning to think I was hallucinating.

I have the tapered ends of the springs pointed up. The small "eye" of the spring fits around the alignment holes in the top of the pocket. Rotating the spring moved it rearward in the pocket.

I would love to hear from someone who has a set of factory springs laying around loose. I suspect the small coils at the top end of the factory springs are probably offset to one side. When the springs are placed in the pockets, the passenger side spring faces the opposite direction than the driver side spring. That's why the upper spring pockets have different offsets. The small coils on the aftermarket springs are centered. That puts one of them toward the rear of the pocket and the other one toward the front of the pocket. If anyone has a set of factory front springs handy, please snap a picture from the top side of the springs so we can see if the small top coils are offset.

Thanks!

Originally Posted by leegreen

The different offset of the upper spring pocket appears to be normal.

this is a ~ 81 squarebody cross member and the pockets are offset, Drivers is further forward. I marked the picture in red where the ends of these upper pockets are

Attachment 2402062

Maybe it matters more that the upper, tapered end of the spring sits in the pocket, is that what you have now?

[leegreen]

The springs that came installed in that crossmember appeared to be original and they were identical side-side. I sold them two weeks ago and deleted the photos though.

Is your ride height the same L & R still? If the spring is not aligned with top pocket it wont seat over the ring and that side will sit higher.

[JohnIL]

You make a good point about ride height. It's not noticeably out of whack, but I will measure tonight.

John

Originally Posted by leegreen

The springs that came installed in that crossmember appeared to be original and they were identical side-side. I sold them two weeks ago and deleted the photos though.

Is your ride height the same L & R still? If the spring is not aligned with top pocket it wont seat over the ring and that side will sit higher.

[JohnIL]

I found a picture online of a pair of NOS front springs for a square body. I'm sure these springs have a different spring rate, but the picture illustrates the problem pretty well.

The stock springs were not "tapered". They were straight from top to bottom, except for the top coil, which is offset to one side. The picture shows pretty clearly that the top coil is offset toward the bottom of the picture. This is why the upper spring pockets are offset in the cross member. The springs are set in the pockets with the offsets facing opposite directions, one toward the front, one toward the rear.

The problem with my aftermarket springs is that the top coil is closer to centered. The offset of the top coil isn't nearly as pronounced as the stock springs.

At the top of this thread, I said I have LMC 2" lowering springs. I was wrong. I was going off of information I got from the previous owner. He may have ordered them from LMC, but they're not LMC branded springs. Once I got the springs removed, the are clearly marked CPP and have CPP part numbers. I'm not knocking CPP. I have lots of their other parts on the truck and I'm happy with the way they fit and perform. With that said, I'm wondering if I would be better off with a different brand of springs.

I need 2" lowering springs. What brand are others using on their trucks? And, have you have good luck with fit and function? I'll take any suggestions I can get.

Thanks.
John

[JohnIL]

Lee,
I measured both sides when I got home tonight. The truck appears to be almost precisely level. The tops of both front wheel wells measure 31 3/8". I think I'm good where I am. I may order a new set of springs, if anyone has a good brand suggestion, but for now, it's drivable as it is.

Thanks.
John

Originally Posted by leegreen

The springs that came installed in that crossmember appeared to be original and they were identical side-side. I sold them two weeks ago and deleted the photos though.

Is your ride height the same L & R still? If the spring is not aligned with top pocket it wont seat over the ring and that side will sit higher.

[leegreen]

I think this picture explains it, OEM springs the flat end of spring indexes on upper spring cup. Aftermarket have round end, it can be clocked anywhere.

[rbruno68]

You may have figured it out, but I pulled the CPP springs I have for my truck. I went with stock height springs but 2 inch drop spindles. I have my originals as well. The originals are a little taller which I thought would not be the case since they have been carrying the weight of the truck for 60 years. The CPP have one more coil. And the originals are about a1/4 inch bigger in diameter as you can see in one of the pics. I guess if the CPPs are shorter they are probably stiffer to get the same ride height as originals. The tops of the CPPS are different the the top coil on the originals and the originals have two different top coils as you have seen in your pics.
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[JohnIL]

Bruno, you rock! Thank you for the pictures. My CPP 2" lowering springs look exactly the same as your stock height CPP springs. They're just shorter, obviously. The top coils of the factory springs definitely look different.

John

Originally Posted by rbruno68

You may have figured it out, but I pulled the CPP springs I have for my truck. I went with stock height springs but 2 inch drop spindles. I have my originals as well. The originals are a little taller which I thought would not be the case since they have been carrying the weight of the truck for 60 years. The CPP have one more coil. And the originals are about a1/4 inch bigger in diameter as you can see in one of the pics. I guess if the CPPs are shorter they are probably stiffer to get the same ride height as originals. The tops of the CPPS are different the the top coil on the originals and the originals have two different top coils as you have seen in your pics.
[ATTACH]Attachment 2402223[/ATTACH]
[ATTACH]Attachment 2402226[/ATTACH]

[rbruno68]

Since I will hopefully be doing this in the near future with aftermarket springs, do you make sure the spring is set correctly in the lower control arm and just let the top sit where ever it wants? Just curious how to install the spring if the top doesn't sit like originals.
Rob

[leegreen]

My conclusion here is that clocking the top of the spring so the end of it sits in the pocket is more important than clocking the bottom.

Some thoughts to support that
-gm made the springs and pockets so the top had to be clocked or it could not go together
-misalignment of the narrow diameter upper coil will bend the spring more than the same misalignment at lower, wider diameter coil

it may be that the round end after market spring will not sit into the pocket right at the very end of the recess end the way the straight ended OEM one did and the ideal location will be slight rotated away from the end of pocket