main leaf spring GMU lettering on a C3

[Ken C.]

Took apart the leaf spring on my 72. Heard people mention the letters GLS being on main spring? I have GMU on my main spring about 6in. from ends. just curious about this.
Took spring apart and had Eaton send me a main spring. Going to try and see how ride height is with this addition to my 8 other leafs. Reason being spring was sitting low. Slight smile to spring when looking at it from the rear.

Special thanks to Gary B. for use of cup tool for spring. Worked great.

[Gary B.]

Re: main leaf spring GMU lettering on a C3

Ken,
The GMU embossing is well-documented. Here's a photo of an example that someone sent me back in 2001.

Gary

GMU on 9-leaf.jpg

[Gary B.]

Re: main leaf spring GMU lettering on a C3

Ken,

Here's a 2nd example from another person who sent me an image. This one with a - between the M and the U.

Gary

GM-U on 9-leaf II.jpg

[Alan S.]

Re: main leaf spring GMU lettering on a C3

Hi,
Here's one from my 71 (6589) with a 'dash' as in Gary's second example.
Regards,
Alan

[Gary B.]

Re: main leaf spring GMU lettering on a C3

Alan,

It's struck some people as odd that the manufacturer would put some sort of embossing that must represent a stress riser to some degree out at the end of the main leaf, where fatigue strength is most important.

Gary

[Terry M.]

Re: main leaf spring GMU lettering on a C3

Gary
I would bet that "enbossment" is on the steel before it is hot rolled to the proper thickness. Those letters look deformed to me.

[Wayne M.]

Re: main leaf spring GMU lettering on a C3

Gary
I would bet that "enbossment" is on the steel before it is hot rolled to the proper thickness. Those letters look deformed to me.

Agree -- in comparison, here's what the GLS looks like.

[Gary B.]

Re: main leaf spring GMU lettering on a C3

Gary
I would bet that "enbossment" is on the steel before it is hot rolled to the proper thickness. Those letters look deformed to me.

Terry,

That may be true, but nonetheless they probably still create some amount of stress concentration.

Gary

[Terry M.]

Re: main leaf spring GMU lettering on a C3

No argument from me there. However, I can't say I have seen a lot of broken springs at those letters.

[Gary B.]

Re: main leaf spring GMU lettering on a C3

No argument from me there. However, I can't say I have seen a lot of broken springs at those letters.

Same here.

Gary