Damage to Rear Leaf Spring from PowderCoating ??
Thread Starter
Racer
Joined: Feb 2007
Posts: 366
Likes: 1
Damage to Rear Leaf Spring from PowderCoating ??
When I first had this chassis together (before the decision to coat the frame)....we had the suspension only coated...including the rear leaf spring assembly.
Upon reassembly, I had a HELL OF A TIME getting the spring into place.
Once together the rear of the car looked like it had an 6" lift.....
You couldn't even push the car due to the fact that the half-shafts were binding.
I know this is not right, because when we dragged the car out of the original owners garage, the whole car was nice and low.
Anyway, I took some pics of the rear spring and some measurements...
The coater told me he's never had a problem coating leafs.
Is it possible the heat re-arc'd the springs ?? It's only 400 degrees (??)
Here are the pics and dimensions...mabey someone can give me a comparison....
Thanks
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Upon reassembly, I had a HELL OF A TIME getting the spring into place.
Once together the rear of the car looked like it had an 6" lift.....
You couldn't even push the car due to the fact that the half-shafts were binding.
I know this is not right, because when we dragged the car out of the original owners garage, the whole car was nice and low.
Anyway, I took some pics of the rear spring and some measurements...
The coater told me he's never had a problem coating leafs.
Is it possible the heat re-arc'd the springs ?? It's only 400 degrees (??)
Here are the pics and dimensions...mabey someone can give me a comparison....
Thanks
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Last edited by Z069; Jan 13, 2008 at 11:33 PM.
Le Mans Master
Joined: Jan 2006
Posts: 6,497
Likes: 136
From: Butler Pa
My guess would be that the additional friction between the leaves caused by the powder coating isn't letting them slide against each other. Do you have the plastic thingys (can't remember what they're called right now) installed between the leaves? I can't see them in the pictures.
Thread Starter
Racer
Joined: Feb 2007
Posts: 366
Likes: 1
My guess would be that the additional friction between the leaves caused by the powder coating isn't letting them slide against each other. Do you have the plastic thingys (can't remember what they're called right now) installed between the leaves? I can't see them in the pictures.
I'm telling you, this rear spring has major tention now.
I guess we need to purchase a new spring.
What types of aftermarket leaf-packs are available ??
Thanks
John
Racer
Joined: Dec 2004
Posts: 410
Likes: 0
From: Wichita Kansas
Comming from a heat treating backround, I doubt 400 F made any difference. If the temperature was too high it would make the spring softer or temper it and that would have a tendency to take the arch out or relax the spring. Take a picture of the assembled rear and post it on this blog to see if we can find any assembly errors.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,112
From: Crossville TN
400F would certainly cause some tempering "activity" with the spring. Apparently [from the photo] it caused the spring to release some internal stresses and bowed the heck out of it. I'm a little surprised that happened, but do you really know that the temp only went to 400F? (I suspect it was higher than that.)
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Melting Slicks
Joined: Oct 2002
Posts: 2,865
Likes: 1
From: I may be getting old but I refuse to grow up
400F would certainly cause some tempering "activity" with the spring. Apparently [from the photo] it caused the spring to release some internal stresses and bowed the heck out of it. I'm a little surprised that happened, but do you really know that the temp only went to 400F? (I suspect it was higher than that.)
I had my spring powder coated and I just measured it and where you are showing 11" mine is only 7 1/4"Steve
Le Mans Master
Joined: Feb 2000
Posts: 7,032
Likes: 2
From: Newburgh NY
Looks familiar. This was my 63 spring after re-arching. Definately have to roll it around a bit. I can't imagine 400 degrees would cause it to bend that much but then again metalurgy is not my thing. 
Pro
Joined: Dec 2006
Posts: 582
Likes: 3
From: Glen Allen (Richmond) Virginia
I had the same issue after I had my springs powdercoated. The car sat way up until I drove it a bit. I did end up having to go with longer spring bolts so that I could pull the a$$ down. I always suspected that the actual powdercoating held the springs in a more arched position (remember each leaf is apart for powdercoating) coupled with the thickness of the new liners. At theend of the day I got the back end down and the ride is supurb. 
Racer
Joined: Dec 2004
Posts: 410
Likes: 0
From: Wichita Kansas
There is a lesson to be learned here. Do not let any of your high strength steel parts, i.e. springs, axles, gears, rods, cranks etc. ever see over 200 F. And never let any aluminum parts get over 200F. Unless you know exactly what the material is and what temperatures it was tempered at or what that particular alloy was designed to handle. And while were at it don't have your high strength steel parts cyrogenicaly treated without being properly tempered afterwards. Not sure, go find a degreed Metalurgist.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,112
From: Crossville TN
An interesting side-note:
Cryo-hardening is really just a metallugic oddity which is being marketed for big buck$. Just because the surface hardness of a metal gets 1 to 2 points harder after being placed in a really nasty environment isn't a good reason to throw money at something. Anyone ever consider "What else happens to the metal when it's subjected to extremely low temperatures?" Well, for one thing, there can be a spontaneous separation of the boundary layer between "surface hardened" and "core material"....while it is in use... or when it is just sitting on a shelf NOT being used. Yep...it can happen. Lesson learned: Don't throw money at WEIRD sounding stuff! It may have some basis in fact, but rarely is it beneficial.
Cryo-hardening is really just a metallugic oddity which is being marketed for big buck$. Just because the surface hardness of a metal gets 1 to 2 points harder after being placed in a really nasty environment isn't a good reason to throw money at something. Anyone ever consider "What else happens to the metal when it's subjected to extremely low temperatures?" Well, for one thing, there can be a spontaneous separation of the boundary layer between "surface hardened" and "core material"....while it is in use... or when it is just sitting on a shelf NOT being used. Yep...it can happen. Lesson learned: Don't throw money at WEIRD sounding stuff! It may have some basis in fact, but rarely is it beneficial.
Team Owner
Joined: Oct 2004
Posts: 23,831
Likes: 10
From: Springfield MO
St. Jude Donor '07
My guess would be that the additional friction between the leaves caused by the powder coating isn't letting them slide against each other. Do you have the plastic thingys (can't remember what they're called right now) installed between the leaves? I can't see them in the pictures.
There is a lesson to be learned here. Do not let any of your high strength steel parts, i.e. springs, axles, gears, rods, cranks etc. ever see over 200 F. And never let any aluminum parts get over 200F. Unless you know exactly what the material is and what temperatures it was tempered at or what that particular alloy was designed to handle. And while were at it don't have your high strength steel parts cyrogenicaly treated without being properly tempered afterwards. Not sure, go find a degreed Metalurgist.
Racer
Joined: Dec 2004
Posts: 410
Likes: 0
From: Wichita Kansas
I'm pretty sure rods, cranks, etc. are going to be seeing temps in excess of 200*F... [/QUOTE]
Rods and cranks will reach whatever the temperature of the oil gets, 250F? The high quality ones are made from 4340 steel but not hardened very high, with the cranks being nitrided. They probably can go well over 300 F....still don't do it unless you know what the prior processing history of the part was. Some steels, like carburized gears are tempered at 250F, anything over that will soften them.
[/QUOTE]Rods and cranks will reach whatever the temperature of the oil gets, 250F? The high quality ones are made from 4340 steel but not hardened very high, with the cranks being nitrided. They probably can go well over 300 F....still don't do it unless you know what the prior processing history of the part was. Some steels, like carburized gears are tempered at 250F, anything over that will soften them.
Burning Brakes
Joined: Dec 2007
Posts: 952
Likes: 0
Comming from a heat treating backround, I doubt 400 F made any difference. If the temperature was too high it would make the spring softer or temper it and that would have a tendency to take the arch out or relax the spring. Take a picture of the assembled rear and post it on this blog to see if we can find any assembly errors.
