NewbVetteGuy

I have a very low mileage 79 FE7 Gymkhana L82 and I'm curious what suspension modifications would make the biggest bang-for-the-buck improvement given that most of the typical C3 recommendations have already been made from the factory with the FE7 Gymkhana suspension.

My goals:

• This is going to be a cruiser that I'll drive to work with during the summer months about twice a week. I drive honestly on some really nice new smooth roads. I want a nice soft ride that doesn't result in worse performance than the stock FE7s, though.
• The stock FE7 ride height is pretty ridiculously high especially in the rear; it's 4x4-esque. I definitely want to lower the ride height (But I've got 18s on it so not too much.) -I'd also love to see the car lose some weight by going to composite leaf spring.

If I'm reading correctly the 79 FE7 kit has a 9 leaf rear spring @ about 300lbs and both front and rear sway bars.

79 was the last year before the switch to the lighter weight composite rear leaf springs, too; if I'm not mistaken.

The car was already switched to Gas shocks, but I think they're about as cheap of gas shocks as you can get (Sears brand); they've got very few miles on them.

The radiator is getting replaced with an aluminum radiator and the stock junk heads are getting replaced with aluminum 64ccs- not sure if this front-end weight loss is enough to justify going with lighter weight springs in the front or not.

I have no idea what size the front and rear sway bars were in 79 but I've read some thread where people indicated that the rears are especially undersized.


-None of the bushings on the car have ever been replaced so that's first on my list -What should come next?

Should I do the 330lb VBP rear composite leaf replacement first?
Bilstein HDs?
Front springs?
Bigger spreader bars?
-How much would the 330lb VBP composite leaf spring lower the rear-end? -Should I still get the lowering bracket?


If you had this setup and had a suspension budget of $500 -what would you do?

What about a $1,000 suspension budget?


Thanks,
Adam

jb78L-82

A few corrections first...the Gymkhana suspension rear spring is a 7 leaf steel spring. If you have the 9 leaf rear spring, it is not the FE7 spring. Only the Gymkhana cars have a 7/16 rear sway bar...no OEM GM type rear bar..no gymkhana suspension. The composite rear spring was only available in 81/82 C3's and only with the BASE suspension...Gymkhana cars in 80/81/82 all had steel rear springs. Lastly any C3 with a improper rear adjustment or spring will not sit correctly...not just the gymkhana cars but the base suspension as well.

If you have a gymkhana car and a gymkhana rear spring (which it does not sound like), I would recommend a 360 composite with Bilstein HD or sport shocks. Add competition adjustable hiem joint struts and you would be very happy. Total cost for all three components about $700.

MelWff

You state you want a nice soft ride, you should be looking at the 300 LB VBP spring. This quote is from the Duntov website:
"The 78/79 F-41 vettes had 292 lb 7 leaf rear springs. the base corvettes in those years (78/79) had 9 leaf steel springs rated at 260 Lbs."
You have to do the springs and shocks together.
If the front isnt sagging leave them alone.
The rear bar is only 7/16"
Bigger spreader bars? You meant sway bars I assume but a spreader bar in the front is a great idea.
The rear is lowered by switching to longer spring bolts, from 6" to 8".

jb78L-82

The 7 leaf gymkhana spring in 1979 was 292 lbs but the base rear spring was rated at 198lbs, NOT 260 lbs. A composite spring of 360 lbs will easily ride much smoother with quality shocks than the BASE steel spring 198. I have been in a few C3's from the 78-80 era with base steel springs and the ride in my 78 gymkhana car with a 360 composite is far superior. I would not recommend a composite spring of less than 330 lbs for a base suspension corvette and 360-420 lbs composite for the gymkhana cars. With a composite spring, you can run MUCH higher spring rates than with a steel spring but with a BETTER ride than the steel spring of less rating.

MelWff

Out of curiosity then why do they make a 300 lbs spring if not for the exact purpose of a very soft ride? Somebody has to be buying them.

GAVelle

I think the 300 lbs/in fiberglass spring is mainly intended for small block C2s without A/C, which I think may be a little lighter than a comparably equipped C3.

jb78L-82

I am sure that someone does buy them

The point is the composite's ride quality is SO MUCH BETTER than a steel rear spring. If steel and composite rear springs were comparable when looking at ratings, why don't vendors make a 200 lb composite to replace the 198lbs steel spring? A 300 lbs composite rear spring rides BETTER than the 198lbs steel spring and by offering the 300lbs composite that spring will still provide decent spring performance with a great ride. Ever ride in a 81/82 with the base composite spring of 198lbs? It rides more like a Cadillac than a sports car....total marshmallow. A 300 lbs composite compared to the 330 is not that different so might as we'll get the best performance with the 330 spring with very little loss of ride quality. My 360 composite with Bilstein Sports is firm but not at all harsh. A 330 lbs composite spring with Bilstein HD's would be a great ride but would still retain some sports car quality handling IMCO. Just an opinion from years of experience (1986 installation of my 360 spring) with my setup.

Knowing what I know, I would suggest a 330lbs composite with Bilstein HD's for base corvettes and 420 lbs composite with Bilstein Sports if I ever needed to replace my 360 spring with my gymkhana suspension.

bluedawg

Times 2, except definently go with bilstien sport, make sure that composite spring has either the 8" or 10" bolts so that you can adjust the height to your liking, if you are going to replace the strut rods. Make sure to buy the shock mount bolts as usually your originals get trashed in the process of removal and that there is a left and right side to then, so make sure you don't buy just the left side or just the right for that matter (don't ask how I learned the last part of that...haha)there is an ongoing debate between poll and stock bushings, i don't know what you should go with there, about the only thing I can say there is that the original bushings lasted a long time and that there have been a couple of forum brothers that had issues with the differential cracking out a big hole and the ones that this happened too had the poly pinion snubber bushing, was it the bushing, i don't know, but I won't put a poly bushing there, i know, I might as well be burning witches at the stake with no trial. Any ways, good luck and rember some of the bushings are a pain in the a$$ to get out with out an acetylene torch.

7t9l82

I have the 550# front springs and 360# rear spring with QA1 non adjustables. QA1 set up my shocks for what they felt would be very good out of the box. The car rides better than stock by far and cornering isn't even comporable. If I did it again I would do the exact same thing. I thought after the fact I should have got the adjustables but after driving it all I could do with an adjustment **** is screw it up.
A strut brace is an absolute must also.

NewbVetteGuy

Yea, I got the 7 vs. 9 leaf thing backwards. I just assumed that the stiffer suspension would be 9 leaf; I didn't actually count the # of leafs in the suspension (my car is 1,500 miles away right now).

I'm on the fence between the 330lb and 360lb composite monoleaf, though (I'm thinking that I'd appreciate a bit of a cushier / smoother ride so I'm leaning towards the 330lb, but if the Gymkahana was essentially a 360lb composite equivalent then I feel like the whole suspension system would be less thrown out of whack if I go with the 360...). Just the spring is $359, strut rod kit with heim joints is $421.99, (That's $781 without any mounting hardware and with no shocks; the Bilstein HD rears seem to be right at $100 each if you're lucky so more like $1,000 and I'm guessing then some. That just covers the rears, too.

What do the strut rod kits with Heim Joints do for me that just a super cheap 8" bolt on the leaf spring won't do? -I'm not asking to be difficult; I find the whole subject of suspension really complicated and confusing. -It definitely seems like going with the Heim Joint+strut rod kit gets more more than just the ability to adjust the rear ride height.


Also, is just refreshing the rear suspension and leaving the front suspension going to really screw things up for me? I've read enough cautious tales of just changing one piece at a time in a suspension vs. getting a properly matched suspension upgrade set that this makes me slightly nervous.


I think I'm just going to hold off on any suspension changes (other than replacing worn out bushings) out into the future and focus on the other changes I'd like to see because honestly I don't have any real complaints with it as it is today and that buys me some extra time to really think it through because I need to learn a WHOLE LOT more on this front and suspension mods honestly don't excite me as much as some of the other things I have planned.

Thanks again folks, I do appreciate it and feel like I've learned something but most of what you all said went way over my head and I need to do some homework and come back again in a few months...

Adam

NewbVetteGuy

Yea all this suspension stuff is still pretty foreign to me so I'm trying to understand; I'm a bit confused on the difference between a spreader bar and a sway bar. Is it just that the general stiffening bar when its in the rear is called a swap bar and when one is installed in the front it's called a spreader bar?

-I really like how cheap/easy switching from a 6" to an 8" spring bolt is but I've seen some pretty scary pictures on here of cars with suspension parts hanging lower than the lip of the rear rims --I don't want to be dragging suspension on the ground if I get an 8" spring bolt. Would 8" still be safe and higher than the bottom of the rear rims (I've got 18s so I imagine so); is it just the 15" rim and 10" spring bolt combos that end up in the predicament where they'd scrape the ground if they get a rear flat?


Adam

NewbVetteGuy

Great feedback. I'm going to be losing 100-150lbs of weight off of the front end of my car-does this mean I should go with a lighter weight front-spring?

So a strut brace is different than a spreader bar which is different than a sway bar and I should have all three!?! *Sigh* so much to learn...


Adam

MelWff

The strut rod with heim joints has nothing to do with adjusting the height of the car. The spring bolts, 8", are typically required when switching springs to adjust the height. With 18" wheels you have no problem with an 8" inch spring bolt. Again going with your original words, "Soft ride", i would stay away from the heim joints, solid metal, and stick with the factory rubber ended rods. A sway bar, front and rear, is a suspension component used to minimize the leaning of the car while going through a corner. A spreader bar, front on a C3, is used to maintain frame stiffness under all conditions. I'm not clear on the term "strut brace" either.

NewbVetteGuy

That's a good point. Or even a 1980 C3 without AC would be MUCH lighter than my car; mine's a beast.

Started from the 1979 base weight and then adjusted for all the weight adding and subtracting options on my car from post #35 here: https://www.corvetteforum.com/forums...-weight-2.html

And ended up with a from-the-factory weight of 3,608.5 lbs for my pig (cow?) of a 79 L82 (AC weighs 58 lbs on an L82!, FE7 suspension, cruise control, power windows, power locks, auto trans, tilt and telescopic steering, power antennae AM/FM radio, dual rear speakers).

With the things that have already been done and are planned I'm estimating that'll bring it down to 3,383 but still pretty heavy.

It's just crazy that the AC option added 58 lbs!



Adam

NewbVetteGuy

Is because that's what you want out of your Corvette or because you think it'll best meet my goals of having a softer than stock ride with at least as good as stock performance?

-I've read in a few other places that Bilstein Sport seem to be the stiffest possible shock option and that pretty much everything else QA1 non-adjustable, QA1 adjustable, Bilstein HD, KEF (I think that's right) all are going to have a considerably softer ride.


I'm probably NEVER going to take it to a track; I have to deal with it on the highway and during my commute to work twice a week during the summer. I don't want a race car suspension; but given 40 years of time for engineers to improve things I'd like to see the same or slightly better performance with a definitely cushier ride quality. Unless I'm majorly misinterpreting what others have said about the Bilstein Sports they don't sound right for my goals.


Adam

MelWff

With your goals you want the Bilstein HD, the composite spring, larger sway cars, a front spreader bar, and only rubber bushings.

bluedawg

It's because that's what I've got on my vette and I like the way it rides so much that I'm willing to recomend it to you...lol.. we have these speed humps her in the neighborhood out of my harley, 2012 Sierra and my 76 Vette the vette rolls over them the smoothest. I have the 320 lbs spring and bilstien sports, smooth and sporty all at the same time, i had Monroe sensetracs on with the spring and the forum was in a debate one night about shocks and their were 3 kinds and 3 people swore enough by the bilstein that bought a pair. I love them, if theirs a better pair out there one day I'll own them and will talk up then as well...good luck.

NewbVetteGuy

Thanks MelWff, and just so I'm clear. The C3's, even with the FE7 package did NOT come with a spreader bar, right?


I've seen quite a few people on here who have said that every c3 should have a spreader bar.
For $100 it seems like a no brainer: http://www.speeddirect.com/index.php...3-spreader-bar

Adam

MelWff

The spreader bar is purely an aftermarket part and your link points to the bar I installed on my car. It may require some modifications, the center tube had to be shortened and the fan required a 3/8" spacer. It seems to vary car by car as to whether anything has to be done to get it to fit.

Cool bean

My situation is slightly different than yours. I'll describe where I am at the moment, but most importantly, do a search on anything jb78l-82 has to say about suspension. He's got great knowledge on the topic. I am following his guidance for the most part (but i stumbled into it after already redoing my rear suspension to stock (1974 coupe).

Just this week, based on jb78l-82 recommendations, i ordered for front: complete rebuild kit (all poly busings, tie rods, ball joints, bilstien HD shocks, 550 pound springs) Came about $500 including shipping.

Next i'll get spreader bar, and adjustable strut rods for rear.

Hope this helps and good luck!