Topic: fiberglass spring
in Forum: C3 Driveline Components
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Do the fiberglass springs go bad or weaken to the point of replacement or are they pretty durtable?
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Grand Blanc, MI - USA
Joined: 8/7/2002
Posts: 544
Vette(s): 1979, 350sb, as my kids affectionately call it "shit brown" Corvette purchased in 1996. 84,000+ miles. Not a show car, but I love her just the same.
I'm sure like everything they will weaken and break down in time. Heat is a fiberglass spring's enemy so if you install one you have to have a good clearance of your exhaust around it.
I have had mine on the Pride and Joy for several years now and I have no complaints. I know there are several other members here who have made the switch as well. If you are not going to be competing in NCRS events then I will go out on a limb here and suggest that you will not be disappointed with the performance and feel of the fiberglass spring.
Please note: The replacement of the spring is not the only thing that needs to be done with this upgrade. Most times new shocks are required in the rear that match the damping rate of the spring. I used KYB2 springs with mine. Hope you get the responses you are looking for.
Composites offer many advantages over any form of steel spring. Their weight advantage is the most notable one – There is often a 60% weight savings over steel leafs. Race-car builders and owners know how valuable this advantage is. They do not de-arch as they age as most steel leafs do. They do not corrode. And, the composite material has a compliance characteristic that steel does not have, allowing selection from a greater range of spring rates with vastly superior ride and handling characteristics.
corvette440hp
I appreciate the replies.
I have a fiberglass spring now, but am changing out the tranny to manual, having the pumpkin rebuilt and once the rebuild man got the pumpkin open, he called me to show me where the side yokes had failed and the center pin was also scarred, which we are replacing.
He thought that could have been a result of the spring weaking over time. I am also changing out all the bushings associated with the carrier while I have her down. I was asking a generic questions w/o getting too deep into what I was doing.
thanks,
gurtz
What gear ratio did you decide to go with?
corvette440hp

Moderator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20218
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
The 'glass spring will not sag due to age, or mileage. However, it can be damaged by scratches/gouges, or extreme heat. I doubt the spring had anything to do with the wear on the yokes, or the center pin of the diff. These parts wear due to the design...the halfshafts are part of the suspension, and they carry a lot of forces from the wheels thru the yokes, to the pin. It is simply a matter of when the wear will occur...not IF. They all will wear, regardless of spring choice.
If you do a lot of twisty-curvy, high speed driving, it wears the pin/yokes quicker. "Normal" driving will still wear the components, just not as fast. It still take time to cause the wear...it don't happen overnight, but rather over long periods of time.
If you do a lot of twisty-curvy, high speed driving, it wears the pin/yokes quicker. "Normal" driving will still wear the components, just not as fast. It still take time to cause the wear...it don't happen overnight, but rather over long periods of time.

Joel Adams
C3VR Lifetime Member #56
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corvette440hp
To answer your question, as I could not swap out the 4 speed for a 5 speed and the closest gear upgrade was a 3.54 with my current case, I opted to rebuild the 2.87. I get her on da highway alot and don't care for the excessive tacking.
I screwed up, I should have got the TKO600 with the 3.54! NO doubt in my mind, after I got all the great threads from fellow members, but I had the 4 speed too long and could not swap it back!
Guy did a great job for 200 clams - crawfish or mud bugs/down here plus my parts rebuilding the diff.
Stuck the tranny on last night, will hopefully have everything in this Sunday!
Thanks for asking
I'm glad that things worked out for you........enjoy

corvette440hp
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Oak Creek, WI - USA
Joined: 5/21/2008
Posts: 1965
Vette(s): 1981 Great White Shark. Red Interior, 350/190 hp. PS, PB (SS), A/C CC, T-Tops. Served three years in Active Duty Army, then Retired Air Force after 34 years! Badger State Vettes Car Club. 175,000 Original miles!! Now own a 1998 C-5!
QurtZ !! Dark Metallic Blue ?? Not many factory 1981's with that color, or did you paint it that color??
Former Member
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Hobbs, NM - USA
Joined: 2/17/2009
Posts: 4
Vette(s): 1968 small block convertable
I put a glass leaf spring on my 68 small block along with smart struts. I have noticed when I punch it the rear end swops down. kinda sucks.
in Forum: C3 Driveline Components
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