Motive 3.90 gears installed today!

['03BlkMM]

Before all of the 4.XX gear guys show up and start bashing, I installed 3.90's because they fit the criteria I wanted. Anyway, I had a set of Motive 3.90 gears installed this morning. I've spent the last couple of hours getting the shift points where they needed to be. Overall I'm very happy with the results. The car feels like it has a good bit more power off the line and doesn't feel like it drops out of the powerband after the shifts like it did with the 3.55's. I now get a 2nd gear scratch everytime it hits 2nd and its possible to spin the tires without powerbraking it when taking off. Gotta like that!:burnout:

When searching I've seen where a lot of people have asked about Motive's gear quality. In case your wondering. The gears are very quiet, quieter than the stockers as a matter of fact. But I think we saw the reason for that. The stock gears had too much backlash, about .020". The guy that did the install normally does Mustang work. But I would highly recommend him if anyone is looking for an installer in DFW. The install with Royal Purple gear oil was about 30% cheaper than most of the dealers charge. If you want to know what he charges just PM me and I'll send you to his website. By the way he installed the gears the right way, setting up the pinion depth, backlash and then checking the wear pattern with marking compound. I hung out, chatted and watched over his shoulder while he worked. :D

[Directedby]

I put 3:90's in my 1969 Mach I and loved them. Congrats. Good choice.

[Wires]

There's only about a 5% difference between 3.90 and 4.10. In fact, I almost wish I had gone with the 3.90 instead of the 4.10, and gone with some slightly smaller tires to make up the difference. (but then I'd have to worry about lowering it, and the complications with that, yadda yadda)


No bashing from me - it's your car. I'm glad you got it the way you want it.

['03BlkMM]

There's only about a 5% difference between 3.90 and 4.10. In fact, I almost wish I had gone with the 3.90 instead of the 4.10, and gone with some slightly smaller tires to make up the difference. (but then I'd have to worry about lowering it, and the complications with that, yadda yadda)


No bashing from me - it's your car. I'm glad you got it the way you want it.
Thats actually one of the reasons that I wanted the 3.90's was that I'm thinking about going with a 45 series tire which would give me more effective gearing than a 4.10 car with the 55 series tires.

[Joe Walsh]

Glad to see you used the 3.90s.... :2thumbs:
I was considering them myself because 3.73s are not much of a step from the OEM 3.55s and I wasn't sure if I wanted to go all the way to the 4.10s.
Most of my driving is on the highway at 70-75 mph and although the Marauder has tall rear tires, I was concerned about using 4.10s.
I'll have to wait on my gear choice until I decide what size/height rear tires I put on when I buy my new rims.

[SergntMac]

Not sure why anyone would flame you, but I see your point. 3:90 gears are fine, some opt for 4:30s over 4:10s, nothing wrong with diversity. While 4:10s are most often suggested because the ratio is a "sweet spot" of compromise for most applications, as long as you thought things out (and it seems you have), it's your car, build it the way you want it.

[twolow]

I'm actually considering a 2:90 if the gas prices do not get better! :help:

[RoyLPita]

What did the gears go for and where did you get them from????

['03BlkMM]

What did the gears go for and where did you get them from????
I won't quote any prices. But I bought them at mustangtuning.com. They have good prices and free shipping. I got them about 5 days after ordering them, so they're pretty quick on the shipping also.

['03BlkMM]

Glad to see you used the 3.90s.... :2thumbs:
I was considering them myself because 3.73s are not much of a step from the OEM 3.55s and I wasn't sure if I wanted to go all the way to the 4.10s.
Most of my driving is on the highway at 70-75 mph and although the Marauder has tall rear tires, I was concerned about using 4.10s.
I'll have to wait on my gear choice until I decide what size/height rear tires I put on when I buy my new rims.
Although 3.73's are better than 3.55's, I didn't think the 3.73's would be enough for me. I wanted to be able to at least feel a SOTP difference.

[RoyLPita]

I won't quote any prices. But I bought them at mustangtuning.com. They have good prices and free shipping. I got them about 5 days after ordering them, so they're pretty quick on the shipping also.

Thanx for the info.

[RoyLPita]

How will you tune the MM to handle the speedo change? Also, will having all 235-50-18 tires with the 3.90 gears work like 4.10s with stock rear tires?

['03BlkMM]

How will you tune the MM to handle the speedo change? Also, will having all 235-50-18 tires with the 3.90 gears work like 4.10s with stock rear tires?

I show about 9 rpm's of difference between the 3.90 + 235/50 combo and 4.10 + 245/55 combo at 75mph. Basically they are the same...

I'm using the SCT xcalibrator and quicktune to make the changes. Dennis R. sent me the tune file for my base tune and I'm manipulating it to work with the 3.90's. It took me about a half dozen tweeks at the laptop and trips down a deserted road and I've got everything set up about where I want it.

[911Racing]

It looks like you did some research on the gears. I'm currently between chosing 3.90s or 4.10s, the car is a daily driver with 20's (275/35/20 in the rear) alittle taller than stock tire. I plan on doing every mod possible (including a blower). What would you suggest? I'm fairly new to the mod scene, I'm a mustang guy for the most part but any input would be great! Thanks for your time, Keith V.

[twolow]

I think you need a 4:10 to make up for having that huge of a wheel.

['03BlkMM]

It looks like you did some research on the gears. I'm currently between chosing 3.90s or 4.10s, the car is a daily driver with 20's (275/35/20 in the rear) alittle taller than stock tire. I plan on doing every mod possible (including a blower). What would you suggest? I'm fairly new to the mod scene, I'm a mustang guy for the most part but any input would be great! Thanks for your time, Keith V.

That tire is actually 1" shorter than the stock 245/55/18.
Here is the calculator that I use. http://www.net-comber.com/tirecalc.html

If your going with a supercharger then depending on what type of SC you buy you might be just fine with the stock gears. A lot of it is going to depend on what you plan on doing with the car. I would decide what SC you plan on running then decide what else you need.

[FordNut]

I actually considered 3.90s when I changed mine, but went with 4.10s mostly because it is available from more manufacturers. Competition is good.

[RoyLPita]

I show about 9 rpm's of difference between the 3.90 + 235/50 combo and 4.10 + 245/55 combo at 75mph. Basically they are the same...

I'm using the SCT xcalibrator and quicktune to make the changes. Dennis R. sent me the tune file for my base tune and I'm manipulating it to work with the 3.90's. It took me about a half dozen tweeks at the laptop and trips down a deserted road and I've got everything set up about where I want it.

Very helpful info. Thanx.

[jgc61sr2002]

Congrats , I would agree that the 3:90 gear ratio is a good all around #.

[Kennyrauder]

Kennyrauder from Canada!!!! I would highly recommend Dennis Reinhart. Do yourself a big favour & call him..... you won,t be sorry. He did a Vortec install for me & my Marauder is now a killer!!!!904-276-5003

[Aren Jay]

275/35/20's are 27.58 inches.

235/50/18's are 27.25 inches.

245/55/18's are 28.61 inches.

255/55/18's are 29 inches.

[Aren Jay]

I just don't know why you would want a 3.90 gear, unless you need to go faster than 190 mph.

[sd8683]

I just don't know why you would want a 3.90 gear, unless you need to go faster than 190 mph.

You do realize this thread is 2 and a half years rite???

[Blk Mamba]

I'm actually considering a 2:90 if the gas prices do not get better! :help:


Well gas prices didn't get any better, did you go with the 2.90's, BTW, It would be self defeating anyway, getting off the line would either eat your savings, or take a long time.

[ctrlraven]

I never thought about 3.90 gears. I had a set of Motive 4.10s that I just sold to another member cause I don't plan on doing any racing until fall. I know when I ran my car with drag radials with an effective rear gear of 3.89 my 3500 stall loved it and knocked off half a second of my previous time with street tires als having a corrected revs per mile tune for spot on shifting helped.

[vkirkend]

I'm actually considering a 2:90 if the gas prices do not get better! :help:

:run::laugh: