Chance81

On an 02 ls1, I recently added 3.73 moser gears with moser axles, OBX longtube headers with ORY on a magnamouth catback. New poly motor and tranny mounts and torque arm bushing and had the car dynotuned. My issue is now the car runs significantly slower than it did when all I had was 3.23 gears, slp loudmouth and a diablosport predator tune. I used to could smoke tires and get sideways and be pinned back all the way to 155 nice and smooth, now it wont smoke tires and when I get to 90 the car feels like its going to vibrate to pieces and explode all over the road so I wont take it any faster than that. I have no idea whats going on here, I thought the car would be alot faster. Any insight would be highly appreciated.

98z8uup

iTrader: (7)

Well you lost some top end when you went to the 373 gear, and for the car vibrateing. Go back to a stock trans mount that should make it run nice and smooth.

Mrkid

I have the same headers, exhaust, and rear-end setup. I have poly motor and trans mounts with no vibration. And I have an MS3 cam...
First off, I assume you have all of the o2 sensors installed? No lights? How does the car idle? Do you have the stock torque arm? Did you install a new U-joint?
Start with those, and we can go from there.

Chance81

All of the o2 sensors are installed. The rear ones have been tuned out. No ses lights. The car idles perfect. I have the stock torque arm, I just put a new poly bushing in it. I havent done new u joints. I was thinking about that so I will go by and get that swapped out and maybe have them check my driveshaft to make sure its balanced. So if you take your car over 100 it runs just fine?

ULTIMATEORANGESS

iTrader: (4)

i wonder if your old tune caused a problem with your recent one.

Chance81

Before I had it dynotuned, I restored my factory tune from the diablo back into the car. It didnt run all that well factory. I had it dynotuned and was reading a forum on tweaking a diablotune, so I reinstalled the diablo tune and it stored the dynotune in its memory and it ran worse with the tweaked diablotune so I reinstalled the dynotune back into the car and thats where it currently stands. Still runs just like it did when they dynotuned it.

CamaroZ28_LS1

iTrader: (5)

weird. My camaro got a lot faster with headers, I have the OBX headers as well. I need the poly engine mounts as my steering shaft hits my header pipe once in a great while. I think it's your tune personally. Maybe a tune up could help. some NGK TR55r's and that re tune on good plugs. oh and with an Auto you kill your top end with 3.73's.

Mrkid

My is smooth all the way up to 150...seriously
I had to replace my u-joint because I damaged it during removal. One of the caps was seized in the yoke. I forgot, but did moser recommend a differant u-joint? I lost my paperwork.

Chance81

Im thinkin I might order up some new 3.23's and pull the 3.73's.. I miss blowin down country back highways at around 140. Im also going to swap out that U-joint. The garage that did my gears mentioned nothing about u joints, but I figured something was up when I was gettin the vibations that felt like they were coming form the driveshaft area. I am also gonna have them check to see if the shaft is balanced. Ill keep updated.

CamaroZ28_LS1

iTrader: (5)

keep us updated for sure of what you find.

Mrkid

Keep the gears. Get the vibration straightened out, and the speed shouldn't be an issue. If you do decide to change them, don't go so low. 3.42's would be the lowest I would want.

SOMbitch

iTrader: (8)

Pulling your 3.73's would be a waste and are not your problem....

Chance81

Alright, well hopefully the U-Joints will fix my issue. If not, Ill check on maybe going back to rubber tranny mounts if possible since my engine mounts are poly and ive heard mixed reviews of having different mounts on engine/tranny. Ill keep updated.

CamaroZ28_LS1

iTrader: (5)

yea I have heard not to run the Poly trans mount. Could be your vibration. You could how ever put the rear end up in the air on jack stands and run the car in the air to see if there is a vibration from the rear end or drive shaft. I did this to find my gears were making a clunking noise and found I broke Ring Gear Teeth.

Chance81

Alright, I took the car to a mechanic who builds race cars for his son.. WIthin 30 minutes he found all my issues. My rear U-joint was seizing, so he replaced both the front and rears. I had a gasket at the rear of my d-shaft that was leaking so he relplaced that. He took my d-shaft and had it balanced up to 3600 rpm. The shop that put my rear gears in 8 months ago had completely screwed them up. I cant remember everything but something was at 0 when its supposed to be between 24 and 26, pinion angles were wrong, backlash was at 12 so he adjusted it to 6 and some other things. Wear on the gears was minimal so when he fixed it up and put it back together there was zero noise. Now the car drives like its supposed to. There is zero vibration up to 140 (was fast as road would allow) and it takes off great and I have no more clunking or whining noises. WIll definately be taking car to him from now on. I paid the other shop $600 to put those gears in and I even took it back to them a few days later and said something wasnt right. They said all aftermarket gears make noise and that it was acceptable..Bullcrap. Guess ill have to chunk that money up to a learning experience. Now to get the shocks swapped out.

Head Hunter

iTrader: (14)

Glad to hear you got it figured out - when I had my 3.73 gears installed I had no noise so not sure where your first installer came up with that.

Chance81

The car drives 1000 times better than it did, but after driving it around in town stop sign to stop sign, I still have a little clunking noise going on. The gear noises are gone and the vibration but there is still a little clunking when I give it just a little gas and let off. Im going to take it back on monday and see if theres something else overlooked. Just had the Torque arm bushing replaced with a poly mount.. But the clunk definatley comes from the rear.. Ill update.

Mrkid

Aren't you glad you kept those gears!?

As for the clunk, make sure the bolts that hold the torque arm to the rear are all tight. They are notorious for coming loose. Especially on the top.