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Discussion Starter #1
are 3.73's a good upgrade for 94 LX thunderbirds with 4.6 V8s? i want to lower the gear ratio so as to get a better jump. i also have ford 8.8 limited slip differential, will that pose problems to the half shafts? I have read that i need to get an aftermarket chip such as a super chip for the transmission to shift correctly when i go to 3.73's, so my questions are as follows.

3.73's and a limited slip differential, are they going to pose problems to my halfshafts?

and do i need a superchip to be able to run 3.73's, i was planning on getting a superchip anyways, but i was wondering if it was absolutely necessary.

Thank you
-Marc
 

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Motorboatin' SOB, Headlight Cleaning Guru
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your half shafts will be fine.

as for the chip, find out what gear ratio you have now via the driver side door jamb sticker. note the AX code, then refer to the gear ratio chart in the tech articles. if you have 3.08s, save up for a chip. if you have 3.27s, a chip isnt needed. i believe that if you go more than two steps (i.e., 3.08->(one step)3.27->(two)3.55->(three)3.73), you need a chip. could be wrong, though. i have a different tranny than you.
 

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I'll go with big mike. Though, there have been people to make the jump along with doing the jmod and they be alright. It's all about the timing.. things happen quicker/sooner with the 3.73s over the stock gears than what the eec is expecting. The Jmod can help with that some. The other issue, tied in with another, is your speed limiter will drop without the chip/tune to readjust it since the EEC knows no better. This has something to do with the driveshaft as well (Jerry's transmission thesis covers this aspect, found in the Tech Articles section). Many here will tell you to go with 3.73s as a minimum. But, anymore gear and you'll need a speedcal to permanently fix the speedo to read right.
 

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big mike said:
your half shafts will be fine.

as for the chip, find out what gear ratio you have now via the driver side door jamb sticker. note the AX code, then refer to the gear ratio chart in the tech articles. if you have 3.08s, save up for a chip. if you have 3.27s, a chip isnt needed. i believe that if you go more than two steps (i.e., 3.08->(one step)3.27->(two)3.55->(three)3.73), you need a chip. could be wrong, though. i have a different tranny than you.


2 higher or lower gears and the eec will adjust :cool:
 

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well I put 3.73's on my mark from 3.27's. Let me tell you although it was drivable and everything the shifts were so terribly early it was annoying to drive. I have the correct speedo gear in, it's just the programming needed to be changed. I've heard the thing saying you can go two steps without a chip before but I think it's a bunch of BS. It may not be absolutely necessary to drive, but for it to shift correctly and not too early it is.

Think of it like this, your car can run with a few spark plug wires off........but dosen't it drive a hell of a lot better when they are on??
 

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95BLKLSC said:
well I put 3.73's on my mark from 3.27's. Let me tell you although it was drivable and everything the shifts were so terribly early it was annoying to drive. I have the correct speedo gear in, it's just the programming needed to be changed. I've heard the thing saying you can go two steps without a chip before but I think it's a bunch of BS. It may not be absolutely necessary to drive, but for it to shift correctly and not too early it is.

Think of it like this, your car can run with a few spark plug wires off........but dosen't it drive a hell of a lot better when they are on??
It shifts at about the same RPM levels the car does stock. What's BS about that? Even though you may not like it, there's nothing incorrect about that. If you dont like the gears, put the car back to stock.
 

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No it didn't, it shifts at a much lower rpm than the stock gears. That's one reason why I got a dyno tune, took care of everything the cars shifts at the correct points now. The BS is about the fact that you can go up two steps in gears and still have it shift perfect. It dosen't, even from 3.27's to 3.73's it shifted way to low before I got a dyno tune. If I was going really easy on the gas it would bog down shifting into second, the rpm's would drop to about 850. THAT'S what the BS is about. Maby the programming is different on birds than marks, although the same thing is claimed on LOD, 2 steps and you are fine. My experiance suggests otherwise.

And I LOVE the gears I would never go back, I just wouldn't plan on doing gears without a chip to put the shift points to the correct spot.
 

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I don't know about the Gen I's, but I know for a fact that the shift programming between a stock Gen II and a stock (94/95) MN-12 is VASTLY different. :beek:

The GEN II's shifting schedule is PATHETIC! :redmad:
 

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yea.....the gen 1's are definately more arrgessive....93's the most. But with the baumann shift kit and the dyno tune my car will rip the tires on any 1-2 shift above 4500.
 

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Discussion Starter #10
well then i suppose 3.55s would be a better option? because either way i am getting a superchip, but if 3.55's are more driveable then thats what i will go with, i just want a better jump than the stock gearing

Thanks for all your advice, and by the way if it helps you know what gear it has stock, its a 94 LX 4.6

-Marc
 

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Motorboatin' SOB, Headlight Cleaning Guru
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3.73s will get you a good jump. i heard 3.55s arent all that.
 

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i second the vote for 3.73's. for all the work involved you mine as well do it right the first time. especially if your going to get a chip anyway.
 

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do at least 3.73's!!!! Don't misunderstand what I was saying. I think you really need a chip to have your car shift at the right points that's all, without it it shifts ways to early even with a 2 step jump. 3.73's are very very comfortable even for a highway cruser. If you don't do a lot of highway commuting go with 4.10's hands down. Don't do any less than 3.73's
 

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Discussion Starter #15
would a superchip be good enough to help the EEC think smart enough? or any suggestions on chips? because my father is buying me a superchip next week, as long as that will work correctly.

i cant wait, 3.73's, a chip, K&N, Exhaust, and lsd.....mmmm lol

just let me know and i will be much appreciative

-Marc
 

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who are you buying it from? Make sure you tell them what your mods are and you won't have a problem.
 

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94V8Thunderbird said:
would a superchip be good enough to help the EEC think smart enough? or any suggestions on chips? because my father is buying me a superchip next week, as long as that will work correctly.

i cant wait, 3.73's, a chip, K&N, Exhaust, and lsd.....mmmm lol

just let me know and i will be much appreciative

-Marc
3.73's = :thumbsup: (But you will lose some mpg on the highway)
chip = :thumbsup: (Like FordFanatic said, www.blueovalchips.com and talk to Lonnie!!)
K&N = :thumbsd: (The filter is too close to the MAF and the oil gets on the wires!)
Exhaust = :thumbsup: (IMHO, not a lot of power to be had, but a LOT better sounding!!)
LSD = :thumbsup: (Assuming you're talking about a Limited Slip Differential... and not the "other" thing to help on "trips" :rofl: )

Just my .02. :thumbsup:
 

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Johnny Bling Bling
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didnt lonnie close up shop?
 

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Discussion Starter #20
its not the K&N FIPK kit, its the K&N panel filter, and i am buying the superchip from performancepartswholesale.com if the superchip wont allow me to use 3.73 then i will call lonnie as u say
 
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