How much will 4:30 gears help my setup?

[MI2QWK4U]

Most of you know what my car has into it, and wonder if anyone has a good idea what adding 4:30 gears to my Marauder for the strip? I am hoping to help my launch and 60ft times, in turn lowering my 1/4 ET. I have been told that the tall gears would help the car launch good and hard. What concerns me is the motor, what kind of rpm will I be pushing at the end of the track? Any constrictive ideas to help out?

[Rider90]

IIRC, in a previous thread it was said you would be pushing 3,000 RPM at 80 MPH with 4.30 gears.

[MI2QWK4U]

IIRC, in a previous thread it was said you would be pushing 3,000 RPM at 80 MPH with 4.30 gears.


What would that translate to if I usually cross the beams doing 115 MPH in the 1/4 mile? Maybe im imagining things, but I thought it reved high with the 3:73 gear.

[Rider90]

For reference, this is where I got the information.

http://www.mercurymarauder.net/forums/showthread.php?t=14393&page=2

[DEFYANT]

Gears will not save you. A few more passes down the 1/4 mile and I'll beatcha! :P

[TripleTransAm]

What would that translate to if I usually cross the beams doing 115 MPH in the 1/4 mile? Maybe im imagining things, but I thought it reved high with the 3:73 gear.


Using the 3000 RPM at 80 MPH for 4.30s in 4th gear, a little math shows that for 115 MPH the RPM would be about 4300.

3000 / 80 = 37.5 RPM per MPH
37.5 x 115 = 4312.5 RPM at 115 mph

This is in 4th, which is what, 0.70:1? Third gear is 1.00:1.

So if you kept it in third gear at 115 mph, you'd be running 6160 RPM with 4.30s.

Here's the math (using the ratio technique I mentioned in that referred thread):

4312 NewRPM
----- = -----------
0.70 (4th) 1.00 (3rd)

A little cross multiplication yields 0.70 x NewRPM = 4312 x 1.00, which simplifies to NewRPM = 4312 / 0.70 = 6160 more or less.

Unless you fudge the rev limiter, you won't be able to go any more aggressive on the rear gears without having a 3-4 upshift to deal with, since anything higher than 4.30s will put you beyond redline (you might already have this problem if your TCC is unlocked as there will always be a little slippage).

Edit: this is all assuming that the change in gears doesn't put you at higher than 115 mph at the traps due to improved performance, in which case if you were doing more than 115 MPH you'd probably have a problem with the stock rev limiter.

[STLR FN]

Dave,
Just strap a rocket booster on the back. That should help your ET's. :lol:

[TripleTransAm]

Dave,
Just strap a rocket booster on the back. That should help your ET's. :lol:

Wrong car... he did just buy an Impala, after all.

http://www.snopes.com/autos/dream/jato.asp

[sailsmen]

I realize your question was gears, how ever since your goal is lower 60' I suggest a TC with a 3,800 stall.

[juno]

http://www.svtoa-atlanta.org/cgi-bin/trans.cgi

Best gear comparison calculator out there. Let's you see the effect of tire sizes also.

4:30 on stock tires will be turning 5812 rpm in 3rd at 115 mph.

Highway driving - 80 is 2820 85 is 3007

Stock is 2336 and 2482 respectively.

[Zack]

I was running about 6700 rpm's throught the traps in 3rd with 4:10's. It was my 11.61 pass. 4:30's are a little too steep for my blood. With your power Dave, you should be competing with me for the fastest Marauder with a single power adder. Set the Nitto's to 15psi and put a loose converter in it and you will achieve your goal. Leave the gears alone.

[MI2QWK4U]

Gears will not save you. A few more passes down the 1/4 mile and I'll beatcha! :P


Ahhhhh....my young padiwan apprentice, you believe that you are ready to best the Master*? I have many tricks up my sleeve yet...




*(of stock motored supercharged w/out nos!)

[MI2QWK4U]

I was running about 6700 rpm's throught the traps in 3rd with 4:10's. It was my 11.61 pass. 4:30's are a little too steep for my blood. With your power Dave, you should be competing with me for the fastest Marauder with a single power adder. Set the Nitto's to 15psi and put a loose converter in it and you will achieve your goal. Leave the gears alone.


Thanks for the input Zack, it is appreciated. I too think the 4:30s are too much. I was thinking of going at least with 4:10s like everyone else. As for competing, im ok with just being at the top with you in the single power adder class, I do worry sometimes about the block holding up, but im not going to build it up until it lets go.

[juno]

I was running about 6700 rpm's throught the traps in 3rd with 4:10's. It was my 11.61 pass. 4:30's are a little too steep for my blood. With your power Dave, you should be competing with me for the fastest Marauder with a single power adder. Set the Nitto's to 15psi and put a loose converter in it and you will achieve your goal. Leave the gears alone.

6700 in 3rd with 4.10s sounds high. What size tires?

[Zack]

6700 in 3rd with 4.10s sounds high. What size tires?
Yeah, forgot to mention I run 295/35/18 drag radials at the track.
2" shorter.

[DEFYANT]

Ahhhhh....my young padiwan apprentice, you believe that you are ready to best the Master*? I have many tricks up my sleeve yet...




*(of stock motored supercharged w/out nos!)

:lol:

The best? nah... not even close. I am well aware that I simply got lucky with that 11.98 run. I will watch for your gear decision.

Signed,
Annikin


P.S. 4:10s are the way to go, IMHO.

[fastblackmerc]

Marauderman has 4.30's installed. He's on a trip to Fla. this week hopefully he'll chime in when he gets to a computer.

[Dragcity]

If your primary goal is quickest 1/4 mile and don't care about much else, go 4:30, hell 4:60 or better yet 5:10.

Remove the rev limiter and let it rip.

Has anyone figured how to get some weight transfer out of these beasts yet?

[sailsmen]

undo the front sway bar. w/ drag radials and a good burn out you prob ok w/ traction.

[MI2QWK4U]

:lol:

The best? nah... not even close. I am well aware that I simply got lucky with that 11.98 run. I will watch for your gear decision.

Signed,
Annikin


P.S. 4:10s are the way to go, IMHO.



Charlie, I hope you dont believe that...I dont believe it for a second. You earned that time, had it coming to you. Its your reward for doing a good job building up your car, so enjoy it! Lid is pushing me towards 4:30s, but I am concerned about the rpms.

[Tallboy]

Dave, if Billy can live with the 4:56 gears, you should be fine with the 4:30s.

Perhaps a PM to Billy would help?

[MI2QWK4U]

Dave, if Billy can live with the 4:56 gears, you should be fine with the 4:30s.

Perhaps a PM to Billy would help?


The only concern with the 4:30s is traction. If they wont hook up then the setup is useless.

[MikesMerc]

You know my opinion Dave. The 4.30s would definitely help your track times. BUT, you'll have to concede something on the street. Heck, I preferred my 3:55s for pure street duty over the 4.10s. Mechanically speaking, its a no brainer. It'll help your times and your RPMs will be fine at the trap. Its the street/strip compromise you need to deal with.

[bigslim]

He won't be driving it too much on the street anyway. Only for short distances. He has the Stangs and that Honda, "OOPs" I mean Impalla for that.;)

[DEFYANT]

Has anyone figured how to get some weight transfer out of these beasts yet?

:hmmm:

PSSSSST....

(turn off the air-ride) ;)