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Q: What are some basics of upgrading an A4?

A: Welcome to the wonderful world of the 4L60E transmission. Let me be the first to congratulate you on entering the world of the broken trans. The 4L60E is not the cruel tyrant on drivetrain parts that its M6 brother is. It is most definitely MUCH more parts-friendly. Too parts-friendly. So friendly, in fact, that it will break itself before it will break other parts. How noble... The problem is that it does this far too often, and even in full built form, this transmission is just NOT very good for real drag racing. Most in search of 10-second and quicker timeslips find that they are just not able to do it with the 4L60E tranny. They usually end up with a TH350, TH400, or 4L80 (the 4L80 being the only one of those which has overdrive).


1. Torque Converter

Selection of your TC is very important. It has much to do with how quick you come off the line, and your 60-foot. The general rule of thumb is: a 3200-3500 stall for the LS1 street/strip car. If you are gearing your car more for drag-only, then 3600-4400 will be more your speed.

Another important number you will see is STR. Without going into a math class, the STR of your TC is part of the torque multiplication that happens in your TC. The higher your STR, the harder your TC hits off the line. You wanna get that 60-foot down? Then get that STR up!


2. Rear End

Since you have the more gentle of the two trannys, the 12-bolt is all you need. Simply apply the same principles as the M6ers do for their 9-inch selection.
 

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Q: How can I strengthen my chassis or upgrade my suspension?
Q: What are some of the suspension parts I should look to ugrade?

A: Okay, you are ready, right? You now have a 500+ rwhp car, with a bulletproof drivetrain. You slap on your slicks and head to the track. On your first run, the track is cold. The 3rd amber lights, and you floor it.... What used to be your tires, is magically transformed into two pillars of billowing smoke. You lose to a cam-only F-body in the next lane.

Frustrated, the next time up you perform a burnout that John Force would envy. People in the stands, stand and cheer and whoop and holler. Determination furrows your brow as you stage. As the bulbs start to drop, you bring your rpms way up... 3rd amber, you peg it. Your teeth feel like they are going to fly to the back of your throat, your rearview mirror pops off and is only stopped by the cable holding it. The front tires head skyward as the track is lost from view for a brief moment. "Wheels up BABY" you scream in your head as you hit second and the track returns to view. You steal a glance at the next lane, the other car is WAY behind; you would look at him in your rearview mirror if it was still hanging properly. You cross the traps well in excess of a 120mph... WOOHOO!!! You hit the brakes and make the turn around. At the ticket booth, there is a older guy looking hard at your ride. As you pull up, he starts cussing you out... you get kicked off the track for the day. 10 seconds... no roll bar... DOH!!! You take your ass-chewing like a champ, only because he hands you that timeslip.

You take your car home... But after a week of driving, you start to notice the car pulling to one side... you get out and inspect. Sure enough, your brand new tires are worn BADLY on one side. What gives? Hey, remember at the beginning of all this, I asked if you wanted a twisted chassis? Well, congratulations, oh master of the clutch dump... You now have one. Hell, you didn't like your now-$80,000 car anyway, right? Yeah, let's keep this from happening too. And while we are at it, we are gonna stop that first race from being a loss too....

Chassis Parts

To keep your chassis happy at this power level, it still only takes a few pieces.

Sub-Frame Connectors
SFCs are nothing more then mild steel or chromoly bars that are welded to both your front and rear subframe. This will greatly minimize chassis flex, and will also assist in the lifting of the front when you launch. They really are one of the first five mods you should do.

Roll Bar/Cage
Under the incredible stress from a drag launch, a roll bar/cage will go one step further in adding to chassis strength. But that is not the reason you install it. You install it to save your life if something goes wrong at the track and you find yourself riding on your roof at 100 mph. Oh yeah, and it will help you avoid getting kicked off the track. If you run faster than 11.49 seconds, then you need a roll bar. Faster than 9.99, then you need a full cage.

K-Member
This part is not so much about strength as it is about losing the weight that your other chassis mods added. You want your car to be strong, but you also want it to be light. This part will more than make up for the extra weight.

Suspension Parts
To keep your tires planted to the ground, you need to upgrade your suspension.

Shocks
Shocks control the up and down motion of both the front and back of your car. Ideally in a drag race, you want your front shocks to allow the front to rise very fast, but to come down slowly. Your rear should assist in transferring weight at first, and then push the rear end toward the ground as forward movement begins. You need adjustable shocks to do this. It would be better to have two-way adjustable shocks if you can.

Springs
Your front springs should be weight-specific. If your car is heavy, then you want a stronger front spring to assist in bringing the front of the car up. If your car is a tin can, then you can go lighter on the front springs. For a stock weight car, I would go with a 300lb front spring; for a really light car, 275lbs should be plenty. There is some debate over the rear springs. Many have gotten their best times on stock rear springs; others use what I use, V6 springs.

Lower Control Arms
LCAs are very important for several reasons. They control wheel hop -- the violent bouncing of your tires as they try to grab traction. And as weight transfers from the front to the back, the LCAs apply downward pressure to the axle housing, planting the tires and aiding in traction.

Torque Arm
The TQ arm does a few vital things for your whole setup. 1. It (along with the LCAs) is the pushing point for your rear end. 2. It acts as a ladder system to assist in weight transfer. 3. It can affect and change the pinion angle of the driveshaft as well. If you intend to race a lot, then you want a chassis-mount torque arm, not a tranny-mount torque arm.

Rear Sway Bar
As the power of your motor is translated through your drivetrain, it create a natural torque to one side; that is, the body tries to twist to one side. A drag solid-end-link rear sway bar, will combat this effect and assist you leaving the line straight and true.

Pan-Hard Bar
As power is sent violently to your rear, the rear end has a natural tendency to move side to side (known to some as the traction shimmy). Your pan-hard bar combats this. If you get an adjustable one, then you can also use it to center your rear end.
 

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when i get some spare time here at work i will add some stuff as well...

good idea chris :thumbsup:
 

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Discussion Starter #44
Yeah and I need LT1 stuff too.

I have 5 LS1 FAQs up already...I'm just doing them as I have time a few here and there.
 

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Chris89gta
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Lt1...

Q: Why does my dyno graph look like a heartrate meter...

A: Cause you car has a POS bastardized Optical Spark Distributor that GM hacked off Mitsubishi, then abandoned when it gave them nothing but problems. You would be better w/ a gerbal and a 10,000 volt cattle prod than that thing!!!
 

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Discussion Starter #46
LMAO..where'd you come up with that one?

Chris89GTA said:
Lt1...

Q: Why does my dyno graph look like a heartrate meter...

A: Cause you car has a POS bastardized Optical Spark Distributor that GM hacked off Mitsubishi, then abandoned when it gave them nothing but problems. You would be better w/ a gerbal and a 10,000 volt cattle prod than that thing!!!
 

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Chris89gta
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LoL I made that one up myself... What got me started though was Jeff's description of the Opti Wiggle on dyno graphs!!!
 

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Q:
I have not upgraded my clutch or my supporting components. The clutch smells very bad and there is a noticable slip.(A quick way to check if your clutch is slipping is to place it in 6th gear at about 2000 rpms and floor it, if the RPM rise quicker than the car accelerates then it is in fact slipping.)

A.
The most common problem with clutches is that the friction material on the disc wears out. The friction material on a clutch disc is very similar to the friction material on the pads of a disc brake, or the shoes of a drum brake -- after a while, it wears away. When most or all of the friction material is gone, the clutch will start to slip and eventually it won't transmit any power from the engine to the wheels. The clutch only wears while the clutch disc and the flywheel are spinning at different speeds. When they are locked together, the friction material is held tightly against the flywheel, and they spin in sync. It is only when the clutch disc is slipping against the flywheel that wearing occurs.

So if you are the type of driver who slips the clutch a lot, you will wear out your clutch a lot faster. If your clutch is slipping this much then it is time for a new clutch disk and flywheel. It is at this time that most people chose to upgrade their whole clutch system (a good idea).
 

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Q.
My clutch will not engage at all. I push the clutch pedal in but it will not go into gear.

A.
There are a few reasons for this. Most often you have a bad throwout bearing or related clutch assembly part. For this particular trouble it is time to replace you clutch assembly and it is also a good idea to either replace your flywheel or have it resurfaced as it will not cost you more to have these parts put in at the same time.
 

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Q:
Under normal driving my clutch works fine, but at wide open throttle my clutch sticks to the floor in 3rd gear and I cannot get it to shift into 4th.

A:
This is a very common problem with LS1 f-bodies. You do not have a fried clutch, the problem 90% of the time happens after you got you car tuned and/or raised your rpm limiter. GM put a restriction in the hydraulic line between the master cylinder and the slave. This restriction lets only a measured amount of clutch fluid flow from one to the other. This restriction was placed in the line to make shifts feel more smooth and to give the pedal a softer feel. The solution to this line restriction is a simple procedure referred to as the drill mod.

In short, it involves removing the line, using a drill to bore out the restriction and then replacing the line. For instruction on doing this yourself, go to www.installuniversity.com
 

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Q.
Under normal driving my clutch feels soft but works fine. Under wide open throttle there are many times I can?t get the car to shift at any given gear until the RPMs come down. I have already done the drill mod (or not). What could it be?

A.
The answer to this problem is simple. However, the reason the problem exists is not so simple. This symptom almost always points to air in your hydraulic lines. The reason this causes problems is because, unlike the clutch fluid that is meant to occupy that space and is very incompressible, the air that now resides in the line can be easily compressed. This creates that "squishy" feeling you get in the clutch pedal. Also (and more importantly) the fact that the air compresses means that the fluid is not pushing the pressure plate to its full disengaged state. Under wide open throttle, where the clutch requires even more pressure to fully disengage the pressure plate, the compression of said air is often severe enough to not allow the pressure plate to disengage at all, making it nearly impossible to get into the next gear up. The fix is to bleed down your clutch hydraulics very carefully until all the air bubbles have been removed. There is a write up on how to bleed your clutch hydraulics on www.installuniversity.com, or you can go to any shop and have it done for a very nominal fee.

Now the bad news: If you never have this problem again (lets say after 3 months), then you are fine and the air probably got there when you performed the drill mod. However, if you have either not done the drill mod, or the symptom returns, then you have a bigger problem. There is most likely a leak in your hydraulic system.

The first culprit to look at is your master / slave line. Inspect it for kinks or pin holes. Next is your slave cylinder. If you have gone through the trouble to remove it go ahead and replace it.
 

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Q.
I just replaced my worn out clutch with a brand new clutch. The clutch grabs strong and does not slip at all, but the clutch disengagement happens only 1-2 inches from the floor board and in wide open throttle at higher RPMs it will not shift into the next gears.

A.
Often, people replace their tired clutch with the latest /greatest clutch, but forget to upgrade the supporting pieces. Because the brand new clutch and flywheel that you just installed have MUCH more material than your old worn-out piece, it takes more pressure to completely disengage the clutch disc from the new flywheel. The first step in fixing this problem is to do the drill mod discussed before. If that does not cure your trouble then it means that your clutch requires much more fluid pressure in order to operate properly. Your stock master--even after the drill mod--can only push a very set amount of fluid. If this set amount is not enough to push the pressure plate then it is time to step up to an adjustable master cylinder. An adjustable master cylinder will allow you to increase the fluid pressure enough to operate your new clutch. It will also allow you to adjust exactly where in your pedal travel your clutch engages and disengages.

There is one company that attempts a more simplistic fix known as a slave shim. This effectively shortens the space that the fluid resides in, therefore putting a "preload" on your fluid pressure. I don?t like this fix for two reasons: 1-it is not adjustable, making it impossible to correct your pressure settings as your clutch pad and flywheel wears, which makes it necessary to replace both of them sooner than you would have to if you could adjust the correct amount of pressure; and 2-because it is not adjustable, it does not account for those whose master cylinder puts out a little more fluid than it was built to. For these people, they will notice that their clutch engages and disengages in the very first 1-2 inches of clutch pedal travel. If this is the case, there is a very good chance that
your clutch is never fully engaging, which will result in a broken or worn out clutch disk very early in the new clutch?s life, and a very displeased customer who thinks this part was junk.
 

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Discussion Starter #54
OK, most of the above stuff has been added to the FAQ. I'm not done putting stuff in but this is a good start. I even wrote a new article on Optisparks for the LT1 FAQ.
 

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AIRBOX/INTAKE QUESTION

I have a '01 t/a LS1 that is going into a 1954 Chevy belair and want to know what option I have for airbox/filter setups as obviously the stock setup probably will not work well in this situatuion? I have considered buying a y-split alum type (corvette type) housing--many avail on e-bay for looks and ease of install, is this a good option or is there a better one? Any other swap info you can provide would be great as well, just got my wiring harness back from Current Performance and want to get started on this project.
 

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Discussion Starter #58
I have a '01 t/a LS1 that is going into a 1954 Chevy belair and want to know what option I have for airbox/filter setups as obviously the stock setup probably will not work well in this situatuion? I have considered buying a y-split alum type (corvette type) housing--many avail on e-bay for looks and ease of install, is this a good option or is there a better one? Any other swap info you can provide would be great as well, just got my wiring harness back from Current Performance and want to get started on this project.

Hi,

This is the wrong place for your question. Please create a new post in the proper technical section.
 
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