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2008 Pontiac Solstice GXP
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Discussion Starter #1
Hi guys,
I’m new to this platform, and had a question regarding suspension and handling.
I’m wondering how I can make my car handle more like my old Miata.
I had a 2006 Mazda Miata and that car would turn and rotate like nothing I’ve ever driven before. It was like it was on tracks.
Quick mountain switch backs were the funnest thing in the world.
My Solstice feels heavier, squatter and much more slow to turn in.
I have BC Racing Coilovers coming in the mail so I’m hoping that will help.
Beyond that, the DDM brace bundle looks interesting.
Is there a good combination of parts that people have used to get the car to turn in tighter, stay flatter and rotate the way a Miata does?
 

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The Miata is a great car.

What type of Solstice do you have? There's more than one suspension type on a Sol, from the factory.

You also want to explore lighter wheels, and talk to the guys at DDM about stiffening the chassis and planting the rear end.
 

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I have no experience with it, but others swear by the DDM brace bundle.
 

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A Solstice will never feel as fast as a Miata. It has a heavier (and stiffer) chassis, and wider tires.

My experience with comparison driving the Miatas that some friends and coworkers own is that the Miatas feel lighter and faster, but the Sky actually is faster on the twisty roads that we have here. Conversely, in unmodified form and aligned for the street, the Miatas will generally outperform my Sky in a parking lot autocross.

The ProBeam (one third of the DDM brace bundle) eliminates an instability in the rear that is caused by flex in the lower inboard suspension hard points, and i consider it a requirement for any Kappa that is driven hard.
 

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A Solstice will never feel as fast as a Miata. It has a heavier (and stiffer) chassis, and wider tires.
Aint that the truth, i remember driving a friends miata during autocross and i spun on the first turn with no throttle. Couldn't believe how easy it was to spin out, the only time i could do that in my solstice is with the throttle.
Completely different cars that will never feel the same.
 

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2008 Pontiac Solstice GXP
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Discussion Starter #6
For reference, my Sol is a 2008 GXP with the FE3 suspension.
Thanks for all the replies, everyone. It’s been very helpful in understanding the differences.
 

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The DDM brace bundle and a set of Michelin Pilot Sport tires gave my 2008 GXP amazing road handling even with the stock suspension.
 
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I agree with great gab. The brace bundle is fantastic. Adding the Michelin Pilot Summer only tires puts it over the top over the stock Goodyears.
 

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First and foremost, our cars are an average of 12 years old. Check your shocks and make sure none are leaking....especially if you have over 50k on it. I just replaced my tires and wheels and saw all 4 of my shocks leaking. :( So that's a project for next spring. Next, as stated, add some bracing. Buy the DDM Works bracking package. Then thirdly, NEVER compare it to a Miata. That's like comparing a Bronco to a Jeep. :)
 

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Discussion Starter #10
First and foremost, our cars are an average of 12 years old. Check your shocks and make sure none are leaking....especially if you have over 50k on it. I just replaced my tires and wheels and saw all 4 of my shocks leaking. :( So that's a project for next spring. Next, as stated, add some bracing. Buy the DDM Works bracking package. Then thirdly, NEVER compare it to a Miata. That's like comparing a Bronco to a Jeep. :)
Good advice. I did check for leaking shocks and all that and they seem fine, but yes, mine’s 12 years old now with 82K on the clock.
Bracing and short shifter are in my cart for DDM Works after the coilovers go on.
Why wouldn’t I compare a Solstice to a Miata? Every publication did in 2006 and and again with the new Bronco to the current Jeep Wrangler. It seems like an obvious comparison to me. What am I missing?
 

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I agree with great gab. The brace bundle is fantastic. Adding the Michelin Pilot Summer only tires puts it over the top over the stock Goodyears.
I have the Michelin tires on mine as well and love them. Comparing them to the Goodyears though is hard as ANYTHING is better than the Goodyears.
 
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DDM brace bundle ,PAW adjustable sway bars , Koni Sport shocks ,Eibach springs ,Kazera light weight wheels ,Dunlop Sport Maxx tires my set up , car handles like a go cart and is faster on the country road twisties that I drive then my Miata which had springs ,wheels ,and tires .
 

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1) The ProBeam (one third of the DDM brace bundle) eliminates an instability in the rear that is caused by flex in the lower inboard suspension hard points, and I consider it a requirement for any Kappa that is driven hard.

2) The ProBeam (one third of the DDM brace bundle) eliminates an instability in the rear that is caused by flex in the lower inboard suspension hard points, and I consider it a requirement for any Kappa that is driven hard.

3) @Sting Ya, front and rear PAW adjustable sway bars are no doubt the proper solution, but I had good plug n play results simply replacing my rear GXP FE3 sway bar with the heavier, ZOK version. Got rid of my excessive understeer. Obviously the car is more fun to drive now. After the fact, I found some explanation by searching this forum:
Here are the front to rear bar stiffness percentages to see overall balance. The FE3 has twice the front stiffness and resulting built in greater understeer vs the base and ZOK bar balance:
FE2 - 107/0 _ FE3 - 221/0 _ ZOK - 88/0
I suppose it's the Ralph Nader effect. He made his mark on GM. Probably has helped keep our insurance rates lower on the GXP's.

4) Might as well do the tunnel brace, it's cheap and easy. Don't forget tune for GXP.

Thanks to @superchunk (wherever you are) and @JohnWR
 

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2007 Pontiac Solstice GXP
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Hi guys,
I’m new to this platform, and had a question regarding suspension and handling.
I’m wondering how I can make my car handle more like my old Miata.
I had a 2006 Mazda Miata and that car would turn and rotate like nothing I’ve ever driven before. It was like it was on tracks.
Quick mountain switch backs were the funnest thing in the world.
My Solstice feels heavier, squatter and much more slow to turn in.
I have BC Racing Coilovers coming in the mail so I’m hoping that will help.
Beyond that, the DDM brace bundle looks interesting.
Is there a good combination of parts that people have used to get the car to turn in tighter, stay flatter and rotate the way a Miata does?
I just installed the DDM Brace Bundle with racing backbone in my 2007 GPX with sport suspension and it was like night and day the difference in the way it cornered and handled. Well worth the minimal investment. After that I installed the factory turbo sensor upgrade to 290 horsepower and that was a noticeable difference too, but the DDM Brace Bundle with racing backbone made the biggest difference. Highly recommended.
 

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Don't forget about a good alignment. If you are concerned with best handling, 2.5 - 3 degrees negative camber in front, all the caster you can get (up to 7.5), 2-2.5 negative camber in rear. 1/8 total toe in in the rear, 1/8 total toe out in the front
 

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WARNING long winded response.

I would have to say

DDM Works Pro Beam
Werks Racing rear frame brace
Werks Racing Front Frame Brace
Werks Racing Front Shock Tower Brace
Backbone (Tunnel) Brace, the mfg doesn't matter.

for the sneakers, best bang for the buck are the Firestone Firehawk Indy 500's. Super cheap (90 bucks each) with CRAZY grip. Only good for about 12-15K on the Solstice because of the soft compound, but at 90 beans each 2-15K miles is fine by me!. They also work really well on wet roads.
.

You can greatly improve the stiffness of the back of the car if you add steel L channel to the Werks rear frame brace, You can also "join" the DDM works pro beam to the Werks frame brace with 2 pieces of flat steel bolted to both the pro beam and the frame brace next to where the control arm bolts to the car. To do the latter you will have to have the L channel added to the frame brace.


I have done a pretty in depth structural analysis of the rear suspension on the Solstice. There are several problems but I am only going to touch base on the one that causes the car to be loose.

Here is the best I can come up with without drawing pictures as to why the car is so loose.

What happens with the solstice back end is the frame rails twist because of how the lower control arm mounts are made. Think of the frame as a bolt and the control arm mount as a wrench. now picture the bolt as if you were looking at the top of the head of it while holding it horizontal and the wrench is hanging down pointing at the ground (this would be you looking at the car from the back). The control arm mounts to the end of the wrench closest to the ground. The control arm mount is like a tower, at the bottom is the point where the control arm attaches and at the top is the frame rail. The 2 are quite a bit of distance apart and this is what gives mechanical advantage to the control arm and why it twists the frame rail. There is a factory brace but it is attached up near the top almost between the frame rails so it really doesn't do a whole hell of a lot to stop the twisting, it does keep the frame rails in parallel. The Pro Beam mounts directly under the stock brace and the frame brace mounts at the bottom where the control arms bolt on.

Now what makes this an even more interesting problem is the control arms are a single piece and there are 2 points where it attaches the the car. The problem is the rear mount point. The front mount point doesn't have any flex at all. This is where it gets goofy. because the back mount of the control arm flexes and the front doesn't it is going to throw off the toe when cornering. and it is going to throw it off in the direction you don't want it to be pointing, to the outside of the corner.

When cornering the outside tire is going to grip and the weight shift if going to cause the control arm to get pushed into the vehicle. Now remember wrench. now think about pushing on the wrench what happens? the bolt turns, just like the frame does. This single thing causes the whole suspension in the back of the car to come out of square. So not only do you end up with the toe going outta wack but you now also end up with the camber changing to a positive.. These are the worst 2 things you can have happen to a suspension in the rear of a car. Positive toe and positive camber bad bad bad mix. When this happens handling goes into the crapper. While both the pro beam and the rear frame brace do help by keeping the control arm mounts on either side of the car the proper distance from one another so they will move in unison. Neither stop the mounts from coming out of square with each other and out of square with the other set of mounts. This is what the 2 added steel plates do is it keeps the the 2 "towers" parallel with each other and also keeps them square with each other.

This is a photo I took of my car when I was installing both the pro beam and the frame brace.
I darkened the rest of the image and made the pro beam and the frame brace more visible.

The pro beam is the upside down pyramid on the top. and the frame brace is on the bottom. Both mount to the same spot in the car on the right and left hand sides. The frame brace also has 2 additional mount points which is where the other control arm mounts are.

If you look above the pro beam you will see 2 bolts. Those 2 bolts are about how high up the frame rails are. the frame rails are directly above where the lower control arms attach. You can see the HUGE distance between the fram rail and the lower control arm.

109417


here is a picture in full color

109419



It is best to install both pieces with the weight on the suspension. I originally bolted it on with the suspension hanging and then removed it so I could paint it then I set the car back onto it's suspension before I mounted the thing again. when I went to bolt it on there as a 3/8" gap between the braces and the control arm mount. If you bolt it while the suspension is hanging you will need to get an alignment to fix the camber and the toe. Everything back there is designed to be where it is supposed to be with the weight of the car sitting on the suspension the purpose to the braces is to keep everything where it's supposed to be from this position. This is the reason why you see the block of wood under the control arms So I could get under the car while keeping the weight on the suspension.
 

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Friend of mine has a spec miata and I do touge with him in my solstice here and there(heading up to TOTD soon). I have all the stiffening stuff people mentioned and rt615k tires. Main difference I find is the miata simply has a stiffer suspension. BC racing ER series with custom spring rates would give you that feeling. But I get it. Stiffer suspension makes it feel more confident in the corners. Is it faster? I don't know. My mini and GTR are set up like that. My solstice still has the stock shocks and it makes it more enjoyable for long drives, its never been my main bomb the hills car.
 

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You are dealing with a car that has quite a bit higher curb weight a Solstice chimes in around 2900 lbs while the Miata is about 2500. that 400 lbs can make a huge difference in handling depending on where the weight is. Plus the solstice does not have a proper suspension out of the box. There are quite a few forum topics about this. just search for "coil overs" and you will be reqarded with lots of information.


the cars are close to being the same length
157.2" Solstice length
157.3" Miata length


1.1" difference in height. so some added weight there.
50.1" Solstice height"
49" Miata height

the Miata sits lower to the ground. So you have a taller vehicle that is higher up off the ground. This translates into more body roll.
5" Solstice ground clearance
4.6" Miata ground clearance

the solstice has a longer wheel base. this translates into the Miata being more "nimble"
95.05" Solstice wheel base
91.7" Miata wheel base


The vehicle width and the track of the tires of the Solstice is wider then the Miata. Now this usually translates into a better handling vehicle only if the height and the ground clearance are the same. Because the solstice is taller and also is higher off the ground the added width will help providing a better footing but it doesn't compensate for all of it.
71" Solstice width
67.7" Miata width

61.4" Solstice front track
61.4" Solstice rear track

58.7" Miata front track
58.9" Miata rear track


The end game is the Miata is lighter sits lower to the ground is shorter and has a smaller wheelbase. Oh course it is going to be more nimble and handle better. It is less of a car in every way ;). There are quite a few options out there for spring/shock upgrades, they range from mild to wild. It all depends on how deep your pockets are. I am not a big person and I find the Miata interior cramped, so that additional headroom and foot room have to come from somewhere and they come at a cost.

The OP stated they have already ordered springs and shocks so there is no point in making suggestions for those. If the rear control arm towers get properly braced it is going to be a night and day difference in how the car handles even using the OE springs and shocks. Properly braced means eliminating as much positive toe and positive camber on the outside corner as possible. This can be done using OTS upgrades and adding onto them a little bit. Take a trip to home depot to pick up some steel, nuts and bolts and spend 2 hours making the needed changes to the OTS parts. It is well worth the time and the 50 bucks additional cost.

I did want to mention the steering gear and the steering wheel. The steering wheel in the solstice is HUGE. I do not remember off hand what GM vehicle it came from, it sure as hell is not the size wheel that belongs in a roadster. That coupled with power steering makes the car super easy to turn. so easy that it can add to the "loose" feeling of the car. so 2 choices here. change the steering wheel and not have a drivers side airbag. or delete the power steering. I deleted my power steering on my Solstice. It removes some of the loose feeling plus you can also feel the road better. The steering gear in the Solstice dampens the feel of the road way to much. You get used to driving the car without the power steering and after 30-60 days of driving it that way it is not noticeable anymore.

It is also a great way to impress the ladies, when they ask if they can drive your car and you let them when they try to turn the steering wheel and can't they are going to think you are Hercules. Deleting the power steering is easy to do. cut the belt for the pump cut the hoses going to the pump and drain the fluid. leave the ends going to the gear open just have them pointing at the ground. put a pan under and turn the steering a bunch of times to get some of the fluid out of the gear. leave the hoses unplugged and pointed down so no debris can get into the gear and it can vent when turning.

No power steering means driving with your laterals and learning how to turn the steering wheel by gripping the inside of the wheel underhanded on the opposite side. It is actually going to extend the life of your tires as well. You should never turn the steering without the car rolling, with power steering you can and doing so is not good for the tire.
 

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How does the kappa platform stack up against the S2K would a simple coilover swap make it handle as well as the s2k?
 

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How does the kappa platform stack up against the S2K would a simple coilover swap make it handle as well as the s2k?
You'd need some magical coilovers to achieve that, get in contact with that shop that wants to put ohlins in our cars.
Look at the bright side though... we have double the amount of torque the s2k puts out, its straightaways its a sitting duck :LOL:
 
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