Project Wannabe GTP: The '96 Grand Prix SE

[ReallySlowGP]

When I was asked back in October if I was interested in this car, I knew it would make a great project to build up for autocross. I've liked 5th gen Grand Prixs for a while, and now that I have one I want to make it worth a damn performance-wise. Stock this car makes 160 horsepower with 185 ft/lbs of torque with a 3.1 liter pushrod v6. Not the best, but that doesn't matter. Engine swaps for this car are well documented and can be done for under $700 easily.


With a car like this the suspension should be upgraded before one even considers triple turbo supercharging the engine to run 3 second quarter miles. Thankfully, this car has the sport package, so it already had a stiffer suspension system from the factory. What I am working on currently is stiffening it up further.

The stiffest sway bars that ever came on one of these first gen W-bodies were 34 mm in the front and 22 mm in the rear, and they came with the 1995-1997 Monte Carlo Z34. I recently pulled these from one in a junkyard.
 

Extremely dirty, but they'll work without any problems.


Here's the front bar after wet sanding. I'm going to give it a fresh layer of Rustoleum once it warms up a little bit.

Thats as far as I have gotten so far. I'm going to wet sand and paint the rear sway bar once I have the time to, and I plan on installing them when I have a warm weekend. To go along with these stiffer sway bars, I am getting front and rear strut tower bars. They are both in the mail, and I'll post them as they arrive. The factory front strut bar only ever came with Oldsmobile Cutlass Convertibles, and mine in particular came from a '96 with the 3.4 DOHC v6, which means if I do swap the engine it'll still fit fine. The rear was made by a guy on the w-body forums in a small batch a few years back, I managed to grab the last one he had, which is lucky because nobody makes strut bars for this generation Grand Prix anymore.

After I install these sway bars, I want to give the car coil-overs, which wouldn't be too hard except the car has a transverse leaf spring in the rear. There are guides on how to ditch this setup and give it traditional coil-overs, so thankfully I have lots of material to help me out. It'll be a pain in the ass but it will be worth it in the end.

This will be one of those projects that will always have improvements that can be made, but that is exactly what I want.

[BLINGMW]

Hmmmmm.... FWD... I will stay tuned for the 3 sec quarter mile  

[ViPER1313]

I am stoked about this build. You may want to do some research into how different sway bars impact a car’s handling in an Autox environment if that is the primary use of this car. Stiffer bars are not necessarily better for AutoX (especially on a FWD car) depending on the suspension geometry. DJ knows a hell of a lot more about this than I do and might be able to give you more pointers.

Be careful with your modifications if you are trying to be competitive at AutoX. I never cared, but that meant my otherwise bone stock SHO with aluminum subframe bushings was competing against fully prepped kit cars in SM. Motor swaps and strut tower bars will likely cost you in classing.

If I were you, I would just drive it at a few events in stock form and see how well it does. For mods, I would start by finding the widest OEM wheels offered on the car, fit them with some R comp takeoffs and have a blast.

[CaptainHenreh]

[Senor_Taylor]

+1 on what Adam says. Either leave it stock with new shocks, one sway bar, and a cat back, or be prepared to fully prep this car to be competitive with the cars you'll be classed with.

For autox, of course.



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[ReallySlowGP]

I am stoked about this build. You may want to do some research into how different sway bars impact a car’s handling in an Autox environment if that is the primary use of this car. Stiffer bars are not necessarily better for AutoX (especially on a FWD car) depending on the suspension geometry. DJ knows a hell of a lot more about this than I do and might be able to give you more pointers.

Be careful with your modifications if you are trying to be competitive at AutoX. I never cared, but that meant my otherwise bone stock SHO with aluminum subframe bushings was competing against fully prepped kit cars in SM. Motor swaps and strut tower bars will likely cost you in classing.

If I were you, I would just drive it at a few events in stock form and see how well it does. For mods, I would start by finding the widest OEM wheels offered on the car, fit them with some R comp takeoffs and have a blast.

I was asking about suspension upgrades on the W body forums for autocross and they suggested the stiffer sway bars. Grand Prix GTPs in 96 already came with the 34mm front sway bar, so I'll essentially be giving it the same suspension as that model with a slightly thicker rear sway bar. I was also having people tell me that their car handled a lot better after doing exactly what I'm planning to do, including the strut bars, so from what I've been told by the members it'll greatly benefit the car. As for autocross classing, NASA already puts it in a non-competitive class unmodified and I was checking through the rules and with only suspension upgrades It looks like I'll still be in that class. Even if I class up I'd be in NXF which I'm ok with, that's where my '98 sedan is placed. I'm not trying to be competitive, at the end of the day it's a Grand Prix so I'm fully expecting to lose to almost everything.

[ReallySlowGP]

Gave the car new poly bushings along with the freshly painted replacement front swaybar today. It's 34mm, the same size as the one originally installed. I'm hopefully going to replace the rear swaybar and bushing this weekend, I'll be going from 12mm to 20 so it will be a huge improvement.

[Jake]

The bigger rear bar will really help it (in theory) want to turn. I don't know W-Body suspension but most FWD cars will react well to that sort of change.

[Senor_Taylor]

What poly bushings are we talking here? Full car or just the sway bars? How strong are the sway bar mounting points?

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[ReallySlowGP]

The bigger rear bar will really help it (in theory) want to turn. I don't know W-Body suspension but most FWD cars will react well to that sort of change.

Yeah, I've been posting on the w-body forums about this as well and they have been telling me the rear bar will help it out a lot. It isn't an aftermarket bar but those 8mm are going to definitely make a difference.

What poly bushings are we talking here? Full car or just the sway bars? How strong are the sway bar mounting points?

For now I am just replacing the sway bar bushings. I intend to replace more of the stock bushings as I upgrade the car, but for now I'm only replacing those. The mounting points at the end for both the front and rear are the control arms, for the front sway bar the center mounts are on the subframe and for the rear I believe they attach to the frame. Thankfully this car has very little rust so the mounts are as strong as they were from the factory.

[ScottyB]

just be careful adding poly to certain suspension points. on the front its likely not a problem, but in the rear it may cause the control arms to bind at certain points where normal rubber would flex enough to allow full articulation. the result of that is your spring rate effectively goes from normal to infinite...not really what you want when you're at the limit.

[ViPER1313]

What poly bushings are we talking here? Full car or just the sway bars? How strong are the sway bar mounting points?

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This is a Pontiac, not a BMW. Ben doesn’t need to worry about frames ripping themselves apart like you do [emoji6]

[ReallySlowGP]

This car is surprisingly fun to drive. Still waiting to put the stiffer rear swaybar in but it was a blast to take onto 33.

[ReallySlowGP]

The first real upgrade I've given this car, Strut bars! The front one is from a 1996 Oldsmobile Cutlass Convertible, they were the only 1st generation W-bodies to receive these from the factory. The rear one was custom made by a guy from the W-body forums who makes surprisingly high quality parts for these cars. I'd be lying if I said I didn't feel like I was driving a completely different car now, it corners much tighter and you can feel the bars bracing the car if you take a turn over 25 mph.

[ReallySlowGP]

Look what the postman brought me today. Sumitomo HTR Z IIs in size 225/60 16. I'll post an update later on how well they handle.


All mounted up


All I need to do now is install the new rear sway bar and fix an oil leak at the oil pump drive unit and it should be ready for autocrossing. This is a surprisingly fun car to drive, I can't wait to throw it around in April!

[Goodspeed]

Oh wow, those take me back - I had HTRZ II's on my Supra. Those tires have been around for-ev-er and definitely helped with some autocross traction situations from the prior rock hard Yokohamas. This car is weird and I like it.

[ReallySlowGP]

Well, I took it onto VIR. Here's the footage I took with a gopro. Spoiler: I spin on my 3rd lap.
https://youtu.be/HaAb6XZzqsw

[ReallySlowGP]

Went to the Verona autocross event today! This was my best (and final) run, I dropped 7 seconds between my first and last run.
https://www.youtube.com/watch?v=FyA4hYPWlPc

[ReallySlowGP]

Here's one of the pictures from the flickr album that was taken from that day.

[ReallySlowGP]

It's been a pretty long time since I've posted anything in this thread so I felt like posting an update with what I've done since last year.

INTERIOR

• Replaced the shredded headliner fabric
  
• Replaced the dry rotted parcel shelf material
  
• Took the entire interior out to properly clean and vacuum the carpet and seats
  

AUDIO

• Replaced the blown rear speakers
  
• Replaced the broken factory radio with a bluetooth head unit from kenwood
  
• Replaced the shitty door speakers with a nice pair of Sonys.
  

SUSPENSION

• New Struts and strut mounts in the front and rear. I used KYB Excel-Gs.
  
• Installed camber bolts in the rear
  
• Installed the 20mm rear sway bar I took out of a Monte Carlo Z34 last year, upgraded from 12mm
  

BRAKES

• Replaced all 4 brake rotors
  
• New EBC Redstuff brake pads
  

EXTERIOR

• Bought a replacement hood from a GTP  that was in better shape than my old one.
  
• Fixed the damn door handles that didn't work half the time
  

With that out of the way, the best way to summarize my car is another bulleted list!
THE GOOD

• The interior is in decent shape, it's comfortable and nothing major is broken.
  
• The car handles so much better now
  
• The stereo sounds great now
  
• Door handles work again
  
• The engine is in great condition. It has a coolant leak under the timing cover but besides that I have no problems with it at all.
  

THE BAD

• That damn coolant leak
  
• Some of the interior pieces I have yet to replace are very brittle and feel like they could break soon (90s car from GM so the usual stuff)
  
• Drivers seat is very worn. The bolstering is fine but the fabric has seen better days.
  
• Alternator will soon need to be replaced.
  
• The rear windows really need to be tinted, the car bakes in the summer.
  

THE UGLY

• Holy shit the paint is awful
  
• see above
  

For a 24 year old car that I got for free, it's doing alright! Since I'm stuck at home for the time being I gave it a very quick rinse with the hose and vacuumed all the crap out of it. Once the trees decide to stop dropping all their damn pollen I'll give it a proper wash, but for now I'm just glad to have taken most of the bird shit off of it. The next thing I'll be doing is picking up a set of crosslace wheels that were an option for this model Grand Prix. I'll be going from 225/60/16 tires to 245/50/16 so hopefully I'll see a slight improvement in grip.