Thread: UPDATE: Suspension help, what's still available?

Here are the components that will transform your GP suspension with non racing parts, if you can still get them:

1. GMPP front and rear sway bars...AKA police sway bars which should be still available
2. GMPP rear trailing arms...not sure they are still available
3. Strut tower braces front/rear...got mine from the W body.com store 15 years ago
4. 97-03 Impala POLICE/Taxi Monroe Sensa A Trac quick Struts (strut/spring Combo) front and rear...rockauto.com. These struts will complete transform the handling and ride of your GP...They ride really well too, not harsh at all but will raise the car about 1 inch over stock.
5. 97-03 Impala POLICE/TAXI front lower control arm-Dorman-rockauto.com

These five changes will transform the suspension of your GP. The Impala Police struts, front/rear, would be the first change, if you are looking to conserve cash....about $400 for 4 or about $1,000 to do all 5 changes yourself

I have no doubt that the Dorman or Addco Swaybars are slightly better than the GMPP Police/Taxi sway bars but I picked mine up from gmpartsdirect a few years ago for $100 for both including a front strut tower brace which I did not use since I have W body heim jointed front and rear strut tower braces...pretty hard to beat that price for those bigger swaybars than stock. I do have all poly sway bar bushings front and rear including front endlinks and those bushings with the GMPP swaybars are pretty much adequate for great handling on the street, not racing. One area that is a big weakness with these cars is the very soft springs and struts and using lowering springs and performance aftermarket struts (not KYB GR2's which I had and thought were worthless versus the Stock Delcos but Bilstein, etc) will make the ride much stiffer and are VERY costly. The surprising aspect of the Impala Police/Taxi Monroe Sensa a Trac Struts/Springs is that they completely eliminated all wallowing, float, and Slop from the suspension AND the ride is SO much better than stock...firm but NOT harsh....They are simply a giant improvement in handling, steering and ride for moderate $$$....and the car does not look like the rear is sitting on the pavement with 2 people in the rear seats anymore.

Wish I had known about those police struts before I bought the KYBs in September....I guess the place for me to start is rear trailing arms, lateral link, and stouter sway bars front and rear, all with poly bushings and where that takes me. The KYBs are softer than I would like, but a lot of the wallowing I am getting is side to side, not up and down, so hoping that stiffer sway bars and new bushings will fix that. I put KYBs on the 98 GT sedan and it rides awesome, this 02 coupe, not so much. So thinking it's something else besides the struts.

I decided to go with the GMPP stuff from Jeg's:
12498648 Strut tower braces F/R
12498643 34mm front sway bar
1249864219mm rear sway bar
Moog K6662 Rear links

No tax, free shipping, so the whole thing is at my door for $218.9, which I didn't think was too bad.

It's a shame GM didn't put these parts on as part of the GTP package to begin with.

Late to the party here but wanted to add a couple of things if you really wanted to tighten it up. Those front and rear strut tower braces really should be installed with brackets, unless you are going to drill some holes which I don't recommend you will need those. The sway bars probably comes with bushings and end links, they will be rubber. Use Moog swaybar K80815 and endlink K5342 which are both poly for the front . You will also need to grab the poly bushing for the rear as well, part number K200318. I would have went with the Mevotech rear end links, same beefy diameter and usually cheaper but Moog is great. Just did all the poly and end links on my Comp G, it was a noticeable difference and got rid of some squeeks. Good luck

I'm all about price usually, The Mevotech end links are the same thickness as Moog, and are about 15 bucks apiece Not sure what all the hype about the Dorman front is, its a boat anchor that comes with rubber bushings you end up replacing before installing. GMPP is hollow and 34mm, and Dorman is solid and 33mm. If I was autocrossing I would probably go with the solid bar, but unless you are taking the car to the limit daily its doubtful much of a difference could be noticed. I purchased my GMPP bar not in the kit new for $55 free shipping, so I didn't pay for the extra bushings only to replace those also.I also used the BMR rear trailing arms on my GXP, they are an excellent value.

Originally Posted by rottonj

I'm all about price usually, The Mevotech end links are the same thickness as Moog, and are about 15 bucks apiece Not sure what all the hype about the Dorman front is, its a boat anchor that comes with rubber bushings you end up replacing before installing. GMPP is hollow and 34mm, and Dorman is solid and 33mm. If I was autocrossing I would probably go with the solid bar, but unless you are taking the car to the limit daily its doubtful much of a difference could be noticed. I purchased my GMPP bar not in the kit new for $55 free shipping, so I didn't pay for the extra bushings only to replace those also.I also used the BMR rear trailing arms on my GXP, they are an excellent value.

I agree! The GMPP sway bars for 99% of those looking for more handling are adequate and the hollow 34mm front police bar is beefier than the OEM 1.25 inch bar and the rear solid bar is bigger than the OEM rear bar. Add poly bushings to both bars and the GMPP bars will be a big improvement. As stated earlier, I did not use the GM front strut brace that came with the GM swaybar kit (still sitting on the floor of my garage) since I had W body store FRONT AND REAR Heim jointed strut braces that I took off of my 2004 Impala in 2006 when I sold the car and put them on the 01 GP...these strut tower braces have a bracket that fits over the studs for the strut and is secured with the strut tower 3 nuts. NOTE that you should have these braces for the FRONT and the REAR for max effect since they greatly stiffen the chassis, eliminate squeaks, and make the suspension much more responsive than cars without the braces. Also, in the rear, the GM 3/4 box trailing arms are very weak and can bend...replacement solid trailing arms is also a must.

I had all of these components for years with KYB Gr-2 struts with the OEM springs and the handling and ride was better than stock but still lacking.....until I changed all the struts to the 2001 Impala Police/Taxi Monroe quick struts. The police struts/springs will have a major additive effect on the whole package and if price is a concern I would change the struts first, put poly bushings on the stock sway bars (keeping the stock bars), and add the Struts tower braces FRONT AND REAR...you will be pleasantly surprised.

The plan is to use the bushings that come with the GMPP bars and Moog endlinks front/rear and the STB's front and rear. I saw the DR brackets, he wants like $100 for a pair. For that kind of coin I can drill a couple holes.... This will be Phase I of the suspension work. Phase II will entail new LCA's and tie rod ends up front, trailing arms and lateral bars in the back with poly bushings all around, then I will get it re-aligned. The KYB struts are staying for now...remember that the springs are what control the stiffness of the ride, the struts are just the dampening of the spring rate. If the ride is still too soft, I may try stiffer springs on the KYB struts.

Trying to dissect what I feel in the seat, I'm not getting a lot of up-down wallow like you would from a really soft suspension, rather I get tossed from side-to-side a lot on uneven roads, making me think the sway bars need some improvement. Hoping to get them installed this weekend and report back.

Originally Posted by coolone

Youre going to brake your balls drilling, lmao... have you figured out how you're going to drill the rear? What about diagonal braces? And the springs may control the stiffness of the RIDE, they are limited in what they do to counteract understeer which is the problem you want to address.

(rotten) It's not hype, and it's not about autocross, that's hype... Nice try though.

the GTP has well known issues regarding steering, the way to correct those issues are well documented. Has nothing to do with pushing the car to its limits but to adjusting and compensating for how the car handles stock vs corrected with some easy steps. Fact is the GMPP front sway, although bigger than stock, is hollow. This means it WILL flex more than a solid bar given the same diameter. I have expressed personal experience from BOTH sways and said nothing about auto road crossing, but thanks. Sell the GMPP bar when you get it and get the Dorman, trust me. And yes, there is a NOTICABLE difference between the two. Like I said, two GP's side by side, identical suspension upgrades except the front sway. The feel was from one minute to the next, ride the same roads, same day, out of one car into another. The GMPP will feel better, but it will NOT feel the same as the SOLID bar. But the biggest difference will be felt when tightening the REAR.

I happen to live in an area that has a lot of curved roads and hills. I can tell you the major difference tuning the suspension properly has made. Couple it along with great rubber on the ground and upgraded braking and the GTP is a different car. You can all do what you want, but if you want to fix the inherent understeering and make the suspension more responsive that will maybe, just maybe help you avoid an accident, I would suggest you look hard at the value of those cheap components... $15 or $500, doesn't make a difference. But using the correct components is what matters. Additionally, when you upgrade the suspension, it's not complete without addressing all the components that are lacking such as the trailing arms. When I removed my stock trailing arms I was shocked that I could twist them by hand... Crazy!

Anyways, there are tried and true methods that have worked to fix the problem of understeering on the GP, you can accept advice or disregard it. The GMPP are the products that should have been stock, so consider them a stock replacement, period. I can tell you my steering is quick and responsive, not dull and lacking. The side to side feel can only be corrected with a different seat that will hold you in place, lol, the GP seats also are well known for sucking! Don't forget to get the right tires too... $100 specials aren't going to help anything either. Bottom line, is just like any mods, you gotta pay to play. Don't expect a $500 suspension to feel like a $1,500+...

Well thanks for the reply , but uh no. Sounds like you are taking this personal. Your not the only one with experience with both bars as I have as well and the difference is minimal so nice try. From a cost perspective as the op was suggesting he was interested in , the GMPP is a better buy, but with either bar I would not use the supplied rubber bushing if tightening it up is the end goal. I only mentioned auto crossing as the Dorman could handle that type of abuse better, don't remember suggesting that you autocrossed. Both bars are an improvement over stock. Either way sounds like he made his purchase, no two people drive the same and people need to do what is best for their situation.

You guys gave some great advice and I did my research and made my decision. It is possible for the front sway bar to be TOO big, making the front too stiff can take you from inherent understeer to inherent oversteer. Glad you like your Dorman sway bar, I'm thinking the GMPP will work better for me. I do have F-body front brakes and brand new Goodyear Eagle Sport All season tires. Sorry to say, I wish I could say money is no object, but it is.

I also heard you on the trailing arms, they will get changed in Phase 2 when I do the front LCAs and tie rod ends.

As far as drilling for the STBs, I should be able to get the rears with my right-angle drill. If not, I may have to fab a bracket like the DR one. I can make my own brackets for a whole lot less than $100/pr.

Originally Posted by Burbman

You guys gave some great advice and I did my research and made my decision. It is possible for the front sway bar to be TOO big, making the front too stiff can take you from inherent understeer to inherent oversteer. Glad you like your Dorman sway bar, I'm thinking the GMPP will work better for me. I do have F-body front brakes and brand new Goodyear Eagle Sport All season tires. Sorry to say, I wish I could say money is no object, but it is.

I also heard you on the trailing arms, they will get changed in Phase 2 when I do the front LCAs and tie rod ends.

As far as drilling for the STBs, I should be able to get the rears with my right-angle drill. If not, I may have to fab a bracket like the DR one. I can make my own brackets for a whole lot less than $100/pr.

I think that there may be some confusion here about how sway bars effect the handling of any particular car, especially a front driver like the GP.A Grand Prix is NOT a sports car and being kind, is really not a a sports sedan in any sense of the word simply because with a front wheel drive platform, trying to get a 3,500-3,600 pound car to handle even remotely neutral is like trying to swim upstream in a river. With 65+% of the vehicle weight over the front axle, all front drivers will inherently understeer. Going to a larger front bar without significantly increasing the size of the rear bar will INCREASE the understeer charracteristics of the GP. There is no way around physics.Putting on a solid front Dorman bigger bar than the GMPP front hollow bar without increasing the rear bar size substantially (I mean a lot like a 7/8-1 inch rear bar) will increase the understeer characteristics of the car but will make the front roll center less during normal driving. Push to the limit and the car will plow into the fields.....Yes a solid bar is better in salt prone areas but my front OEM GM bar lasted 10+ years in the Northeast as an FYI before the endlink on the bar cracked. You need a 50:50 weight bias or 48:52R% weight bias to really make a car handle...think BMW sedans which have a 50:50 weight distribution...