CUTLASS 5658 vs. 5660 real world experience

403Olds

Master Mechanic
May 31, 2014
371
43
South Central Ohio
I've got the 5658/5413 combination with tall ball joints, Fbody sway bar and Hellwig rear sway bar. Currently have QA1 single adjustable shocks, but haven't really found a good adjustment for them, so am going to go Bilstein's, since they get such good reviews. My car sits 6 1/2" to the frame in the front and 7 1/2" in the rear. I'm considering swapping front springs to the 5660's, just wondering if anyway else has done this and can give feedback. I wouldn't mind it sitting up slightly higher in the front, and the handling isn't as balanced as I would like. Seems to understeer a touch. Just wondering how the ride compares. The 5658 are firm, but not jarring. TIA!
 
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Macguyver

SOUTHSIDE MACHINE PERFORMANCE
GBodyForum Sponsor
Mar 21, 2017
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This chassis is designed to understeer . That's why front end geometry is so important on this chassis.

Long answer short, you can cheat poor geometry by limiting suspension travel. 5660 is stiffer and would help with understeer, a bit.
Also rear bar should be about 70% the diameter of the front bar to help with your setup.

Changing just the upper A arms can only do so much. The length and offset of the arms has very little effect on camber change, roll center or overall handling. They add + caster which can make the car track straighter at speed and improve turn in. However too much can make the car feel vague and the steering sluggish so that only goes so far. As the + caster is increased there is a tiny improvement in camber as a side effect when the wheels are turned. Our upper arms have this benefit as well as more caster adjustment. To make any profound improvement in the suspension geometry of cars that need it the actual pivoting points (pickup points) that determine that geometry need to be moved vertically. Road race cars like SCCA, TransAm, LaMans Series race cars and fast DRAG CARS use special taller spindles, raising the upper ball joint pivot points like our Stage 1 and 2 packages do. This was the genesis of our pro Touring Tall Spindles for the GM A and G Body and S series Truck platforms. For years circle track racers that run stock G or F body chassis have used taller truck upper ball joints, which seated improperly to improve the geometry. They’ve been doing this kind of thing for years by fabricating new parts, mixing and matching stock parts, modifying suspension/frame mounts etc. That’s how to win races with a less than perfect factory chassis and a small budget. We’ve taken that race experience, applies new technology and brought it up to date with our SSM STAGE 2 package. Major suspension improvements, not just shiny parts.
They'll physically bolt together and you could drive the car around but there's a catch or two. There's the fact that the original arms on the A and G-Body as well as the S series GM Platform cars were originally designed to droop down over the frame and have the ball joints at the proper angle for a full range of travel. Once you lower the car, go to taller spindles or ball joints etc. the arms end up closer to level and the ball joints end up close to binding at ride height. Hitting a big bump can bind up the ball joints and put a tremendous amount of stress on them as well as the upper A arms and A arm mounting bolts. They'll only take that for so long before something fails...
Much of it also has to do with alignment. A lot of folks think if their car goes straight and doesn't chew up the tires that it's aligned properly and working as well as it can. They're kidding themselves and they're missing out on a LOT of performance. The alignment specs recommended in the `60s and `70s (and even `80s!) were anything but performance oriented. In fact they've changed little since the 1940s. Today almost every car is using power steering and we're all running high performance radial tires (except for the resto guys but that's another story...) these tires are often more than twice the width of the originals, we've also got another 40 years or so of experience to draw on. What's more, once we've corrected the geometry so that it works like a new performance car it demands the same type of alignment those cars run to achieve peak performance.
Modern performance cars run a LOT more + caster and - camber. The + caster helps the cars track better at highway speeds and gives better steering feel. The - camber helps keep the tire's contact patch flat on the road surface during cornering. It's part of what makes new cars drive like new cars. Using these kinds of settings on older cars yields a BIG improvement in drivability and performance but because they were designed around different specs it's usually impossible to attain the best numbers with stock parts and shims. Lowering the car or increasing the effective spindle height with taller spindles or taller ball joints all add more + camber making it ever harder to dial in a - camber setting (which is what we want). That's the big reason for different upper arms. The taller spindles or tall ball joints make the big geometry improvements and the proper upper A arms make it possible to combine the new parts and geometry with the proper performance alignment, an unbeatable combination!

WHAT IS THE STAGE 1?​


The SSM Stage 1
The secret is the combination of the extra tall ball joint to match your new tubular upper arms which greatly improves the camber curves and relocates the roll center. This means more grip and less body lean. The 1" EXTRA tall upper ball joints reverse the backward factory camber curves for a huge increase in grip. They also raise the extremely low factory roll center to dramatically reduce body roll
· For stock and lifted cars this radically corrects poor ball joint angle and helps the arm clear the frame when lifted properly.
· For drag racers SSM Stage 1 Plus allows faster weight transfer and more positive caster for better top end stability.

WHAT IS THE STAGE 2?​


The SSM Stage 2
The stage 2 goes even a step beyond the Stage 1 Plus and further corrects the terrible backward geometry of the factory front suspension, by using Racing Series ball joints, the ONLY ball joints made 100% from US materials in the USA!
They are much stronger, smoother, and longer lasting, than original GM, or any other aftermarket ball joint. The .5" taller lower ball joints further improve the camber curves and roll center location, significantly reducing lateral roll center migration for more predictable behavior.
They also correct the factory bump steer issues by raising the tie rod ends into proper alignment. Now with extremely improved geometry designed for the rigors of SCCA, TransAm and NASCAR your car will truly dominate the street and track!

PRO TOURING TALL SPINDLES?​


The SSM Tall Pro Touring Forged Performance Spindles for the A and G-Body as well as the S series GM Platform. Raises Roll center, lowers center of gravity, eliminates bump steer and creates a negative camber curve that surpasses the C7 Corvette. Uses larger bearings with a wider separation and will accept 11-14 inch rotors. Huge single piston to 8 piston caliper options as well. Bolt on fast ratio steering arms. Even the ball joint tapers are larger. Available in stock and lowered heights.
 
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carnutjw

Master Mechanic
Supporting Member
Sep 17, 2017
406
93
Don't know what your stock specs were(V6,V8,A/C, trans., etc.) but according to MOOG charts, spring rates would have been from 346lbs/in to 424lbs/in. The 5658's are 530lbs/in, and the 5660's are 598lbs/in, so less of a jump there than from original springs. Don't know if that helps. Yeah my answer sucks compared to Mac's. Would take me three days to type and proofread that, but he's right.
 
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81cutlass

Comic Book Super Hero
Feb 16, 2009
3,502
113
Western MN
What is your complaint with the setup as it is?

I have a similar setup (F body sway bar, tall lower ball joints, frame mount rear bar) on my 2+2 with 5660s's. I do have the KYB gas adjust shocks. The only major change I have is that I have aftermarket UCA's from a member here on the forum with taller upper ball joints also. In a drag application my nose raises and lowers a LOT and I need to get a set of stiff adjustable shocks up front.

With my 2+2 (heavy noise) plus an iron LS, AC, and a blower (heat exchanger, pumps, ect) I'd argue the 5660's are on the soft end. An NA olds small block without AC on a 78-80 cutlass would probably be 250lbs less on the nose.

I have no complaints with 5660's as far as ride. I think it is more comfortable with 5660's than the stock springs. Flemming442 on the forum here has 5664's if I recall on his 3800 SII bonneville which is a lot lighter than my setup and hasn't complained about it.

1615304266058.png
 
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403Olds

Master Mechanic
Thread starter
May 31, 2014
371
43
South Central Ohio
I've got the tall upper and lower ball joints, just still not handling as good as I'd like. If I adjust the rear sway bar tighter, it oversteers alot. I've seen many other talk about the 5660, just wondering if there's anyone else out there that's made the switch. I'm running staggered 235/60/15 and 255/60/15's, so that might be contributing poorly to the handling also. Saving up for some 17's.
 

81cutlass

Comic Book Super Hero
Feb 16, 2009
3,502
113
Western MN
I've heard oversteer can be a result of too stiff rear bar. The few autocross people I know that are successful with a g body have actually disconnected their rear sway bars. One of them had a DSE full kit that was $3500+ and went faster without the rear bar. The inside tire on a corner would pick off the ground or reduced weight transfer up front and didn't allow the outside front tire to gain enough weight transfer.

The 15" tires aren't helping either. Nobody makes a 15" stiff-ish sidewall tire that had a treadwear anything close to sticky. If they are BFG radial TA's they are probably rock and a cooper cobra or mastercraft are better but still not a great side load tire.

I'm not an expert but I don't see a few dozen pounds of spring rate up front doing anything. I'd do tire or lighter or no rear bar before I do springs.
 

fleming442

Captain Tenneal
Supporting Member
Dec 26, 2013
13,085
113
Fleming442 on the forum here has 5664's if I recall on his 3800 SII bonneville which is a lot lighter than my setup and hasn't complained about it.
Actually, I have 5662s, and they're still too soft for my liking. I'm getting the 5664s the next time.
 
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403Olds

Master Mechanic
Thread starter
May 31, 2014
371
43
South Central Ohio
Just an update for anyone still interested. I've got about 30 miles on the new setup, the ride is slightly firmer, but the car is better balanced now. I think that the 5658 springs caused the front to grab more, contributing to the oversteer feeling. I also changed to the Bilstein shocks, astro steering shaft and a CS alternator. For some reason the Bilstein's seemed to add a little to the ride height. For summary, I was a 6 1/2" and 7 1/2", now I'm at 7 1/2" and 8" frame rail height. Puts my fender opening about 26" and 26 1/2". Raining here today, I'll get a picture sometime, once I get it cleaned up. Here is a comparison of the springs, 5660 on the left, 5658 on the right. This is with 235/60's on the front and 255/60's on the rear. Both sets of springs were uncut. I can see where installing 5660/5413 combination would need the front springs cut to keep it level with the same size tires all around. Would recommend this setup to anyone wanting more performance. The 5658's are more of a stock ride.
 

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JAMCAR223

Royal Smart Person
Jun 6, 2014
1,711
113
Houston, TX.
I love these spring discussions. I realize all of our cars are setup differently ( options, weight, sway bars, tires, etc. ) Thanks for following up with your thoughts on your new combo.
 
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DROLDS84

Master Mechanic
Feb 15, 2015
440
93
SW Michigan
If your happy go with it...you can always change it later. Don't jump the gun it will handle better as time goes by and your used to it...sounds like you went from worn out stock to a lot of new parts...it will take a little getting used to.
 
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