Sloooow!

[Colt45ws]

I went to the track Friday and participated in the Friday Night Drags.
It went horribly.

(These are bigger than I thought they would be. Ill remake them later.)
The first and second runs I didnt make any changes. I have no idea why it was so much slower the second time. The third slip I pulled out my secret weapon and installed the canned SCT tune. Its a horrible tune and shifts way too high so I have to manually shift to 2nd to force it on earlier than it wants to call for it.
Someone from CVN went with me and said he thought its probably my gears. I was thinking he was right. It does not even shift to 3rd before the end of the quarter. Well, when we first showed up a company was setting up a dyno trailer. I wasnt going to do it. But they looked bored so I said what the heck and threw it on.

I had to do a second gear pull due to no tune. I dont know how much that throws it off.

I bought a stripped rear axle and Im going to work on building it. Itll get 31-spline axles the 05+ Panthers have, 3.55s and a Truetrac. Then just swap it in.

 

[DemoFly]

Why 3.55 rear?

 

[Colt45ws]

Currently I have 2.73.
3.55 because that is the deepest they put in these cars from the factory. Seemed like a reasonable number. Some put in 3.73 or 4.10 too.

 

[DemoFly]

My truck has a 3.55 and it is a boat anchor, couldn't imagine a 2.73. The 3.55 is so much of a boat anchor that guys get better highway economy with 3.73s

My 4th and 5th

1.0, 0.73

Your 3rd and 4th

1.0, 0.70

Are you looking for balance in street/strip or just street? Either way I vote 3.73 or 3.93.

 

[Colt45ws]

Im looking for a reasonable gear for street usage.
You have to remember, you have taller tires than I do. That affects total ratio. So your 3.55 is probably about equivalent to a 3.27 in my car. Just in the gearing, then you have a smaller engine.
I cant get a 3.93. It jumps to 4.10.
If I go 4.10 Ill have to find a AMMX driveshaft out of a year 2000 interceptor. I have an aluminum driveshaft sitting in the garage but with 4.10s its only good to 105 safely. The AMMX is good to 120mph.

 

[Colt45ws]

Actually, I guess aftermarket-wise I can get 3.89 and 3.9, though I have never seen anyone use a set like that. Those gears are interesting because they run the same engine RPM on the highway as the 2.73s with O/D turned off.
Driveshaft situation is not much better. 110MPH for alum and 127MPH for AMMX. Though I would be fine with the alum rating until I can locate an AMMX.

 

[DemoFly]

My truck has 215/75/15s, they are dinky base model size. I'm looking to upgrade.

Not much of a difference



235/55/17
Overall Wheel diameter in Inches 27.177
Wheel Circumference in Inches 85.38
Wheel revolutions per mile 742.098
Wheel revolutions per second @ 65MPH 13.399

215/75/15
Overall Wheel diameter in Inches 27.697
Wheel Circumference in Inches 87.012
Wheel revolutions per mile 728.174
Wheel revolutions per second @ 65MPH 13.148

For me in 5th @ 60mph is 1400RPM, completely out of the powerband, with a 3.73 I would be at 1950.

Food for thought, I still think 3.73s would be perfect unless you do 80% highway, then the 3.55s might be the right choice.

 

[Colt45ws]

Im running 255/45/18. Dia, 27.0 Revs/mile, 770
Ill definitely think about it.

 

[DemoFly]

So the difference between us (with 3.73 gears theoretically) at 60mph is 30RPM.

You w/ 0.70 4th = 1855rpm
Me w/ 0.73 5th = 1885rpm

 

[The_Eric]

I like gear. Lots of gear. IMO, 3.55 is the absolute minimum you want and would prefer 3.73 to 4.10. I feel that 3.73 would be a good compromise for street and strip. Also keep in mind that your 4.6 is only 280 something cubic inches. They're a good runner and have a fair amount of potential, but the old adage "There's no replacement for displacement" still applies. Maybe if you had a 400 plus inch motor, I'd say run some 3.55's...

On the topic of drive shafts, why not order up a custom piece from Denny's or out of a local shop that gives you a healthy safety/strength cushion?

 

[Chris142]

My 340 Duster had a terrible time getting into the 14.s. I would run 15.15, 15.09,15.03 all night no matter what I did. An older guy noticed I was having trouble and he came over to me to offer a suggestion.


He looked at the plug I had out, pulled out some side cutters and he cut the ground electrode off where it bends! Told me to cut the rest off and see what happens.

So we cut all my plugs and put them back in. My next pass was a 14.77!

 

[hardcore302]

I like the Motive Gear 3.90. Somewhere inbetween 3.73 and 4.10 makes me warm and fuzzy.

 

[QuOk]

Video is set to private,Can't see it!

Anything over 3.55 i would use the aluminum shaft.
Over 4.+ AMMX and forced lube tailshaft.

You don't really need the 31 spline for the power level you are at.definately with forced induction though.

 

[Colt45ws]

Thats why. I dont really want to mess with the axle again unless it breaks.
Eventually I want to do a 5.0L stroker and itll be forged of course so throwing on something like a Tork Tech would be nothing.
Video is fixed.

 

[Colt45ws]

Originally Posted By: hardcore302
I like the Motive Gear 3.90. Somewhere inbetween 3.73 and 4.10 makes me warm and fuzzy.

In my searching Im finding whining that those exact gears...whine. I was reading one thread and this one guy pulled apart his diff 4 different times and had multiple people check the clearances and pattern trying to figure out the whine.

 

[SteveSRT8]

Think about it hard!

You need a lot of first gear to get a large boat like ours off the line. With an OD trans you have little to fear.

My car only has a 3.06 but has a 3.6 first gear so the gear is in the trans instead, my best 60 foot time is 1.8x on real street tires. Pull those times and you are a winner.

 

[Colt45ws]

Yeah, Im trying to figure out what gear I want now. I know the Marauder's come with 3.55 and most go to 4.10 as an upgrade. The DOHC is even more of a high-strung engine than the SOHC I have so it works well. I like the idea of 3.90 (or 3.89) but I find a lot of complaints about them so Im trying to decide if I should chance it, or go with one of the more common ratios like 3.73 or 4.10.

 

[ls1mike]

From a guy that spends lots of time in an 11 second Trans Am. I have to ask, why such a huge discussion about gears in a car that runs consistent 16.00s? If you update you may get faster but it will cost anywhere from 500 to 1000 dollars. Why not add some power first and see where that gets you. I ran on 3.42 for rears ticking off low 12's high 11's. The 4.10 put right at 11.70-11.60 consistently.
Your first 1000 dollar modification should be a higher than stock torque converter or power adder, then gears.

 

[The_Eric]

Originally Posted By: ls1mike
From a guy that spends lots of time in an 11 second Trans Am. I have to ask, why such a huge discussion about gears in a car that runs consistent 16.00s? If you update you may get faster but it will cost anywhere from 500 to 1000 dollars. Why not add some power first and see where that gets you. I ran on 3.42 for rears ticking off low 12's high 11's. The 4.10 put right at 11.70-11.60 consistently.
Your first 1000 dollar modification should be a higher than stock torque converter or power adder, then gears.





There's a world of difference between your nearly 350 inch (5.7 liter) LS1 in a what? 3500-3600lb car with 3.42's and the O/P who has a 280 something (4.6 liter) in a 4000+ pound car with 2.73's....

He needs mechanical advantage (gear) and power.


edit: I will say that I agree with you that a looser converter will help him quite a bit too.

 

[Colt45ws]

Ive scaled it before with basically the same way I raced it and it was 4300lbs. That is with me and 1/4 tank of fuel.

Im trying to stage together multiple mods to avoid multiple retunes or that require the same part to come off. I am going to do long tubes and a converter next, and while I have the trans out Ill put on the long tailshaft housing and forced lube mod for the bushing. Along with the shorter PI driveshaft of course. Then it will be ready for gears.