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TRW 340 lb. Leaf Spring

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Old 08-27-2003, 10:43 AM
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l2vette
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Default TRW 340 lb. Leaf Spring

I just installed the TRW mono leaf spring and now my 72 Vette looks like a 4 Wheel Drive!!! The camber is way positive but I'm sure that once adjusted it still won't bring the rear end down. What the @#$! I've read about going to longer bolts but you would think that VBP would sell the kit to make right in the first place. Any thoughts or advice would be appreciated!!
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Old 08-27-2003, 11:14 AM
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Default Re: TRW 340 lb. Leaf Spring (l2vette)

I just went through this. I replaced my spring with the standard 9 leaf and replaced the side yokes and suddenly found myself with hellacious positive camber. I had to replace the 8 inch bolts I bought in anticipation of just this situation. I got some 9 inch 5/8 x 11 bolts which required enlarging the hole in the top of trailing arms and drilling out my bushings a tad. Unfortunately, this puts the spring end really close to the tire. I like how the car sits but I'm going to have to raise it back up for safety's sake and adjust out the camber with the strut rods.
I'm wondering if thse fiberglass springs hold there shape for awhile then settle down after weights been on them for awhile.
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Old 08-27-2003, 11:31 AM
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Default Re: TRW 340 lb. Leaf Spring (FeedVaal)

I don't have a new spring yet, but what I hear from everyone who's had that problem is: drive it, let it settle. Apparently even huge gaps like that tend to flatten out.

Good luck, enjoy it!
Chris
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Old 08-27-2003, 11:55 AM
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Default Re: TRW 340 lb. Leaf Spring (l2vette)

Get the longer bolts.They do sell them. That should solve your problem. Its funny they never say anthing about them. Great customer service. I had to request the longer bolts. I live near Vette Brakes so it wasnt a problem, but I would have hated to make a second trip. Good Luck
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Old 08-27-2003, 11:56 AM
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Default Re: TRW 340 lb. Leaf Spring (FeedVaal)

Thanks for the reply. I hope that is does settle down and I do not have to go with a longer bolt.

:cheers:
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Old 08-27-2003, 12:18 PM
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Default Re: TRW 340 lb. Leaf Spring (l2vette)

I have the TRW spring in the rear and VB&P glass spring in the front and set the ride height when they were installed and it is still at that height some 5 years later. So I don't think glass springs "settle".
I would go with the long bolts.
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Old 08-27-2003, 12:29 PM
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Default Re: TRW 340 lb. Leaf Spring (yellow 72)

Yellow72 is right there, MY rear actual VBP spring never settled one bit...but I had the long bolts....

thing is MY spring is now 7 years old, and so it's a differant shape, long straight and thin front to back, the TRW spring I have seen in the past for a C3 were shaped like a C4 spring....kinda wavey on the sides...really fat near the edges.....I dunno if VBP is selling the TRW springs or not these days....

I thought some time ago the VBP was a better spring design, and still do, but forget just exactly WHY.....

GENE
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Old 08-27-2003, 01:17 PM
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Default Re: TRW 340 lb. Leaf Spring (mrvette)

Correction..........the TRW spring is not from VBP, it was purchased from Muskegon Brakes.
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Old 08-27-2003, 10:38 PM
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Default Re: TRW 340 lb. Leaf Spring (l2vette)

Get a really fat girl friend to go cruising with you. After the right side starts to drop a bit, let her drive for a while. After you get the ride height you want, dump her for a skinny chick (unless you take a liking to her, of course). :jester

Get the longer bolts if the spring doesn't settle down to the ride height that you want.
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Old 08-27-2003, 11:47 PM
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Default Re: TRW 340 lb. Leaf Spring (l2vette)

I just installed the TRW mono leaf spring and now my 72 Vette looks like a 4 Wheel Drive!!!...
....What the @#$! I've read about going to longer bolts but you would think that [Muskegon] would sell the kit to make right in the first place. Any thoughts or advice would be appreciated!!
Replacing my worn out steel spring with a new TRW design composite spring from Muskegon Brake made a fantastic ride imrovement. However, as other forum members have experienced, my Vette sat way too high in the rear following installation. Composite springs will never "settle" a noticeable amount so don't waste time waiting for that to happen. The bottom line is that we little choice but to purchase springs sold by vendors that are not made properly for our Corvettes. Apparently the manufacturers are not taking the basic design parameters into consideration when building springs for our cars. They are disreagarding the measured load height of these springs. Surely all of our Corvettes weigh close enough to the same over the rear spring, so why don't they get it right?
The only reasonable crutch we can apply is to locate, purchase, and install rediculously long end bolts to bring the ride height down to factory specs (or haul a few bags of concrete mix in your car). This is effective but not without compromise because now the ends of your spring assembly will be LOWER than edge of your rim. In the event of a flat tire, I don't think anything should touch the ground before the rim.

Same goes for NEW steel leaf springs. I've read similar complaints about those too. Seems that they also tend to suffer from excessive load height. :rant:
I was unable to find any 10" long grade 8 bolts locally so I ordered some from Vette Brakes and Products (note part number in picture). Let us know how it turns out.
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Old 08-28-2003, 10:36 AM
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Default Re: TRW 340 lb. Leaf Spring (MIKER)

Thanks for the info!! I guess I'm stuck with longer bolts, something I was trying to avoid!!
:(
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Old 08-28-2003, 04:18 PM
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St. Jude Donor '05-'06
Default Re: TRW 340 lb. Leaf Spring (l2vette)

I just installed a TRW 340LB Spring that I bought from Van Steel. Makes the car handle great, and no SQEAKS. Yes it is higher then the old spring. I checked it against the specs in the Chassis Manual.

From memory - In my manual it says that the bottom of the frame should be 8 and 3/4 Inches from the ground. You adjust your rear spring height to attain this. Mine looks high but is at the factory spec height. Perhaps we are all so used to looking at 30 year old cars with worn/sagging springs that when we raise them back up to their correct hieght the look odd. Check you frame height and see how it drives before you spend another $ on new bolts.

PS Now I need new front springs to make the front come up!
:cheers:
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Old 08-28-2003, 09:25 PM
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Default Re: TRW 340 lb. Leaf Spring (stingry)

Perhaps we are all so used to looking at 30 year old cars with worn/sagging springs that when we raise them back up to their correct hieght the look odd.
Your right, PART of the "OMG it looks like a 4x4" syndrome is from being used to seeing our cars with clapped out suspensions but I still believe that the replacement springs (composite and or steel) available to us are built on a "one arch spec fits none" basis. Possibly this is due to a conservative approach to manufacturing. . . "better too much arch than too little" eh!?!???, I don't know if the manufacturers or vendors would even tell us. I'm sure that some customers actually receive a spring that is fairly close to having the proper load height due to random variances in the manufacturing process.
Different taste in overall stance plays a role too. For instance, it sounds like you don't mind the look of a higher stance for your Vette, whereas I prefer a lower stance. Something a bit closer to the minimum curb target height specs. One opinion is not necessarily better than the other, just different.
Based on the GM height specifications for my '80 Vette, http://temp.corvetteforum.net/c3/miker//ride_height.jpg
My ride height in the rear is currently:
104% of MIN, 97% of TARGET, and 90% of MAX.
My ride height in the rear prior to installing longer bolts was:
115% of MIN, 106% of TARGET, and 100% of MAX.
GM allowed a surprisingly large span (~2.3") between MIN and MAX. To me it's the difference between that 4x4 look and that "just right stance".
And yet another problem I had while riding at 100% of MAX ride height spec was the poor geometry of my sway bar end links. You can see the difference in this picture:


Aftermarket springs are apparently no different that most of the other aftermarket parts we purchase for these old Chevrolets, which often times require modifications to fit our application properly. Oh well, I guess that's just part of our hobby.

INFO: Eaton Springs tech info site http://www.eatonsprings.com/tech%20infro.htm
Load Height = how much arch is in a leaf spring when there is a normal load on the spring.
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