New 99 RT/10 owner, few questions on issues/coilovers.

[ViperFan1]

Hello all, located in MD and am finally a Viper owner after 25+ years of dreaming. Got a 99 RT10 with 58k miles, shipped it from Dallas. Came with pretty good maintenance history, Venzano interior, ACR stripes, 18" Forgeline ZX3R-6 wheels and stock wheels, and a muffler delete. I got it for a great price knowing I'd have to upgrade/repair a few things here and there.

So far I've done:
-PPI with compression check and fresh spark plugs, had great numbers.
-New water pump, new tires, new coolant, brake, clutch, diff and trans fluids.
-New IPSCO power steering and bracket pulley, along with IPSCO tensioner, idler, alternator, water pump pulley, new belt. IPSCO trans brace with poly mount.
-New engine mounts, two window regulators rebuilt, 3 new speakers, new smooth tubes and K&N filters, and rear window seal, though I had to reuse the current one as the Temple just didn't want to fit. New battery, new key cut and key fob, AC refilled, and oil change/alignment.
-Single DIN 7" Pioneer flip out and up unit for CarPlay/backup camera. Tried a Boss floating screen but it was far too bright at night and had no buttons/knobs for volume/song switch. Backup camera was quite a pain to wire, but definitely helps.
-New LED's in low beam, high beam, backup lights, fogs.
-Corsa catback, initially paired it with stainless Belanger high flow cats, now running a cat delete instead. Upon install I found that I had no oem heat shielding, only an armor blanket from previous owner, so I added the Sticky Shield and HeatShield protection on the chassis/sills, and around the new pipes on sides and around the diff.

Issues I'm currently struggling with:
-Really want to order coilovers to sharpen the handling and ride. Leaning towards BC Racing which I've had on other cars with no issues, but I'm really struggling to figure out the proper spring rate. I understand the 10/12 is recommended, but I see people saying it rides like garbage and that spring rates 6/8 or 8/14 are much better overall. Was also recommended Aldan's but see more negative reviews than good, same with MCS.
-Sometimes at full throttle from low RPM, it stops accelerating around 5k rpm. As if it hits redline/hits a wall before even close to redline. Was suggested maybe a fuel filter or ignition wires or fuel pump?
-There is a whining sound when on the throttle lightly accelerating in 5-6 gears at low rpm when car is hot or ran for 15+ minutes on highway. Say 1500 rpm at 60-80mph. Trans or clutch or diff sound or it may be normal? Especially heard with windows up.
-Odd NVH sound coming from air vents when accelerating. Like a deep whirring sound, not sure if normal. It sounds like a kitchen blender whirring and increases with RPM.
-Hard top has been adjusted to be tight but is still very squeaky. Looking for a good method or rubber liner to add to minimize the noise?
-Come next year I'd like to upgrade to 18/19" or 19" wheels and possibly go to 3.73 or 3.55 gears eventually. Will probably remove the stripes as well.

 

[ninetyninegts]

Hello all, located in MD and am finally a Viper owner after 25+ years of dreaming. Got a 99 RT10 with 58k miles, shipped it from Dallas. Came with pretty good maintenance history, Venzano interior, ACR stripes, 18" Forgeline ZX3R-6 wheels and stock wheels, and a muffler delete. I got it for a great price knowing I'd have to upgrade/repair a few things here and there.

So far I've done:
-PPI with compression check and fresh spark plugs, had great numbers.
-New water pump, new tires, new coolant, brake, clutch, diff and trans fluids.
-New IPSCO power steering and bracket pulley, along with IPSCO tensioner, idler, alternator, water pump pulley, new belt. IPSCO trans brace with poly mount.
-New engine mounts, two window regulators rebuilt, 3 new speakers, new smooth tubes and K&N filters, and rear window seal, though I had to reuse the current one as the Temple just didn't want to fit. New battery, new key cut and key fob, AC refilled, and oil change/alignment.
-Single DIN 7" Pioneer flip out and up unit for CarPlay/backup camera. Tried a Boss floating screen but it was far too bright at night and had no buttons/knobs for volume/song switch. Backup camera was quite a pain to wire, but definitely helps.
-New LED's in low beam, high beam, backup lights, fogs.
-Corsa catback, initially paired it with stainless Belanger high flow cats, now running a cat delete instead. Upon install I found that I had no oem heat shielding, only an armor blanket from previous owner, so I added the Sticky Shield and HeatShield protection on the chassis/sills, and around the new pipes on sides and around the diff.

Issues I'm currently struggling with:
-Really want to order coilovers to sharpen the handling and ride. Leaning towards BC Racing which I've had on other cars with no issues, but I'm really struggling to figure out the proper spring rate. I understand the 10/12 is recommended, but I see people saying it rides like garbage and that spring rates 6/8 or 8/14 are much better overall. Was also recommended Aldan's but see more negative reviews than good, same with MCS.
-Sometimes at full throttle from low RPM, it stops accelerating around 5k rpm. As if it hits redline/hits a wall before even close to redline. Was suggested maybe a fuel filter or ignition wires or fuel pump?
-There is a whining sound when on the throttle lightly accelerating in 5-6 gears at low rpm when car is hot or ran for 15+ minutes on highway. Say 1500 rpm at 60-80mph. Trans or clutch or diff sound or it may be normal? Especially heard with windows up.
-Odd NVH sound coming from air vents when accelerating. Like a deep whirring sound, not sure if normal. It sounds like a kitchen blender whirring and increases with RPM.
-Hard top has been adjusted to be tight but is still very squeaky. Looking for a good method or rubber liner to add to minimize the noise?
-Come next year I'd like to upgrade to 18/19" or 19" wheels and possibly go to 3.73 or 3.55 gears eventually. Will probably remove the stripes as well.

While doing your suspension I would highly recommend doing polyurethane bushings, made the most difference for mine. I did get the Aldan's and they do fine for the money but if I would do it over again, I would get the best I could afford with external adjusters. Maybe others have suggesting on brands or check the forms for recommended coilovers.

 

[white out]

You have done all the great driver mods that really make the car more enjoyable to own and drive.

I think we have messaged about coilovers - feel free to DM me here - but the standard BC rates are a good setup for street use. Very similar to G2 ACR suspension.

Falling on its face at 5k is odd - replace spark plugs & wires (qualitywires.com), also might want to have the injectors sent out to be cleaned.

RE: driveline sounds, check all your u-joints re: the vibration - they can die from age. Check the crank pulley to make sure it is not loose.

 

[haneifk]

Congrats on the dream coming true! Driving it for the first time is such a surreal experience and will put a smile on your face for years to come.

I didn't see IPSCO solid steering rack bushings on your list. Maybe I missed it but I would definitely recommend. I got a 3.73 diff and have been very happy with it. And for all your NVH. These are very noisy cars. Without actually being there it's hard to tell if it's normal or not. I would just keep an eye on it to see if it gets worse before digging around.
If you're planning on tracking the car you'll need a catch can setup and a little sprout for the power steering reservoir cap. Probably a few other things but can't remember off the top of my head.

Lots of knowledgeable people on this forum so you're at the right place.