Is this right ?

[Bottesini]

Little worried about how well my car is running in the 1/8 (have not made it up to the track yet). I have just recently noticed that I did not have the stock 3.42 gears, but instead if looks like 3.90s (according to my math). For a stock geared car I was not concerned, but with 3.90s I feel it is running a bit slow, especially since it does not feel like a car that has 3.90s. Just does not run through the gears like I would expect. Looking for some suggestions, or if there could be some possible problems that I have not thought up of.

The best I have been able to do is:
60'- 2.0235
330' - 5.3864
1/8th - 8.1129 @ 90.67 MPH

The car has a 226/228 .584/.588 LSA 112 Comp cam (XER lobes)
Kooks long tubes
Custom true dual exhaust
SLP lid and Bellows
Oil catch and a tune
3.90 gears
275/40 R17 BFG G-Force Sport (street tire)

I have within the last 5k miles replaced the plugs, wires, fuel filter.

Here is a pic of my dyno run. I don't think I am having trouble with anything like a clutch robbing power since I am still putting down decent numbers.

[Elimin8tor Z28]

...The best I have been able to do is:
60'- 2.0235
330' - 5.3864
1/8th - 8.1129 @ 90.67 MPH

The car has a 226/228 .584/.588 LSA 112 Comp cam (XER lobes)
Kooks long tubes
Custom true dual exhaust
SLP lid and Bellows
Oil catch and a tune
3.90 gears
275/40 R17 BFG G-Force Sport (street tire)

I have within the last 5k miles replaced the plugs, wires, fuel filter...

Well, I don’t know.

My Z28 runs 8.21 @ 87.20 mph w/ 1.90 60'

My only modifications are: SLP Lid, Custom Exhaust, 3.42 Gears, Mickey Thompson Drag Radials.

I still have Stock Exhaust Manifolds, Stock Torque Converter, etc...

Your trap speed seems low for your mods, only 3 mph more than me.

Is your track at a high altitude?

[Elimin8tor Z28]

Little worried about how well my car is running in the 1/8 (have not made it up to the track yet)...

Wait, do you mean you haven’t made it to a 1/4 mile track, or you haven’t been to any track and you’re using a g-tech thing.

Because those g-tech things are not accurate.

[Bottesini]

Sorry was late and I did not finish the thought fully. I have not made it to a 1/4 mile track yet. The track I ran the 8.11 at was 5 feet above sea level, granted there was high humidity, but just another reason that I am puzzled.

[VENOMOUS]

Hey man, you say you may head to Waco this weekend, we can get together and go to the 1/4 mile track up the road and see what she does. Also you can compare with mine and such.

[Bottesini]

Hey man, you say you may head to Waco this weekend, we can get together and go to the 1/4 mile track up the road and see what she does. Also you can compare with mine and such.

More like next weekend. Not sure if I can get her to a track for a while since the posi is starting to act up.

[VENOMOUS]

More like next weekend. Not sure if I can get her to a track for a while since the posi is starting to act up.

Is it clunking on you? Making sounds as if the suspension is loose?

[Bottesini]

Is it clunking on you? Making sounds as if the suspension is loose?

Last time I came back from the track (2 weeks ago) one side has no rubber on it. It is starting to do one legged burnouts.

[VENOMOUS]

Last time I came back from the track (2 weeks ago) one side has no rubber on it. It is starting to do one legged burnouts.

Have you jacked up the rear end and spun the wheels to see if you hear anything abnormal? It could be that you need rear oil changed. It does have friction modifiers to help actuate the limited slip and if the oil is old and weak it'll tend to spin right only. Worth it to change oil and add bottle of G.M. friction modifer/ limited slip additive. Just my 2 cents!

[Bottesini]

Have you jacked up the rear end and spun the wheels to see if you hear anything abnormal? It could be that you need rear oil changed. It does have friction modifiers to help actuate the limited slip and if the oil is old and weak it'll tend to spin right only. Worth it to change oil and add bottle of G.M. friction modifer/ limited slip additive. Just my 2 cents!

I have not gotten it up in the air yet, odd thing is it is the drivers side that is the one spinning. Other then that it is working perfectly. I might take it up for another day when I can get a spectator to tell me what is going on outside the car.

[VENOMOUS]

I have not gotten it up in the air yet, odd thing is it is the drivers side that is the one spinning. Other then that it is working perfectly. I might take it up for another day when I can get a spectator to tell me what is going on outside the car.

Def sounds like oil replacement and limited slip additive time. Usually , from my experience when it one-legs it's usually the clutches on the limited slip are gone ( usually makes noise, clunking sounds) or the rear end oil is in dire need of change. Hopefully for you the latter.

[Bottesini]

Def sounds like oil replacement and limited slip additive time. Usually , from my experience when it one-legs it's usually the clutches on the limited slip are gone ( usually makes noise, clunking sounds) or the rear end oil is in dire need of change. Hopefully for you the latter.

I am fairly sure it is the clutches since the fluid was changed in Oct and that was at most 10k miles ago. I know it is not helping my 60' times any, but should it be slowing me down that much at the track and from rolls even ?

[VENOMOUS]

I am fairly sure it is the clutches since the fluid was changed in Oct and that was at most 10k miles ago. I know it is not helping my 60' times any, but should it be slowing me down that much at the track and from rolls even ?

Definitley will. you spinning one tire sometimes is not felt because you'll launch straight and not get any kind of sidedrift. When your limited slip works correctly it should launch straight as well unless your tires are not hooking, then you'll get the sidedrift. It may feel as though you are launching well and not spinning but your times suck because in reality your were spinning half way down the track. almost feels as if your clutch were slipping, rpms are there but lack of pull. Actually spining the one tire as the other tries to get feed from the limited slip but does so as an open diffy would do.

[VENOMOUS]

Did you add the little bottle of additive when you changed it in October? Did you actually do it or a tech? He may have not used the right weight and spec oil? Just trying to help before you decide the limited slip is bad. they do have a rep for being crap, but it is usually from someone doing donuts and other mayhem. Straight lauches are what the LS was intended for. Well and getting out of mud and snow in a 4x4.

[Bottesini]

Definitley will. you spinning one tire sometimes is not felt because you'll launch straight and not get any kind of sidedrift. When your limited slip works correctly it should launch straight as well unless your tires are not hooking, then you'll get the sidedrift. It may feel as though you are launching well and not spinning but your times suck because in reality your were spinning half way down the track. almost feels as if your clutch were slipping, rpms are there but lack of pull. Actually spining the one tire as the other tries to get feed from the limited slip but does so as an open diffy would do.

Very good point. I never thought that it might be spinning more then I could tell. I might have to take it down and run it with you watching. Where is the closest track down there ?

Did you add the little bottle of additive when you changed it in October? Did you actually do it or a tech? He may have not used the right weight and spec oil? Just trying to help before you decide the limited slip is bad. they do have a rep for being crap, but it is usually from someone doing donuts and other mayhem. Straight lauches are what the LS was intended for. Well and getting out of mud and snow in a 4x4.

I had a tech do it, actually going in today to ask them about it.

[VENOMOUS]

Very good point. I never thought that it might be spinning more then I could tell. I might have to take it down and run it with you watching. Where is the closest track down there ?



I had a tech do it, actually going in today to ask them about it.

We have two 1/4 mile tracks within 30 minutes of Waco. One is Prarie Hill Raceway and the other is Little River Raceway, I'm sure they both have websites , but I'll check and let you know. Cheap racing , I think 20 to race and enter.

Alot of techs including G.M. techs have used the proper weight oil, but usually leave out the additive. I think the little bottle is like 30 bucks. It affects their profits I guess. Makes a huge difference without it! Of course I'm not guaranteeing your clutches aren't out but I doubt it. I have run across more with the wrong Gear oil and no additive than bad clutches. Only on high Hp cars still abusing the factory ten bolt and kids doing lots of proud donuts tear up the clutches. Although I've seen a couple shit out because of rocking back and forth in the mud or snow continuously till they dug themselves to the bottom of their cars. Both Lslips on both cars went out a couple weeks after their getting stuck incident. The limited slip actually will not engage when driving normal. It takes the sudden accel. to lock up the clutches.

[Bottesini]

Well I think this 10 bolt is running somewhere close to 131k miles so I would not be that surprised if the rear is nearing its end. It is just odd how this car drives and feels like it has 3.42s except for the rpm to mph ratio. Checked the rear today and there is a bit of a leak so very possible that I was just low enough to hurt it some.

Hoping some other people might have some suggestions as to other possible suspects.

Might be the driver mod.

Right now I am taking off at right around 3k and shifting at 6500ish.

[rc74racer]

You need to get out of the hole better and improve your 60ft times. Perhaps some DRs should be your next mod.