4.10 Gears Questions

[Hauser717]

I had the Merc in the shop to get the oil changed because it's too darn cold to do it myself right now. And it's a good thing I did because the mechanics found that the axle is leaking on the driver's side wheel. A nice quote of $600 to have both seals replaced and new brake pads (I guess the oil ruins the pads?) plus the appropriate labor and whatnot.

If I can get my dad's mechanic to do the work, I'll have him do it instead of the dealer due to he'll have lower labor costs and I know that he'll do an excellent job.

So I'm thinking while the rear end is being worked on, why not see about changing the gears. But I want to go in a bit informed if I do this and thus I have questions:

Which rear end is in the Marauder? The 8.8"?

Which should I look at? The 3.72 or 4.10? While the Merc is not my daily driver, it is usually taken out on weekends and is used for the rare travelling I do (usually to see the parents which is an 8 hour round trip).

How will the different gears affect the gas milage?

I am under the assumption that if I do this, I should have a tuner to tell the computer about the change. So I'll be spending an extra ~$700 overall (gears + tuner) to do this. Is it worth the money?

Is there anything else I haven't asked about this issue that I should know?

[JonW]

I did a lot of research on the 4.10s before I bought mine. The factory gear is 3.55. At 70 mph, you will probably see an increase of 400 rpms, and it might cost you 1 mpg or less. I don't have my gears installed yet, so I am going by what I could find out by searching on this board.

You will also need a tuner, along with a gear install kit. Add in a couple hours labor and your figure of about $700 is going to be a little light, but close.

[superford3]

i will also be going with 4.10s but i heard it makes a world of diffference ,and yes the gear oil will ruin brake pads and brake shoes so its right to change them out

[Drock96Marquis]

Which rear end is in the Marauder? The 8.8"?
Yes, 8.8" 28 spline live-axle

[GAMike]

If you do a site search this topic has been covered pretty thoroughly, but I can tell you from personal experience, its well worth the money.

Your right, figure $700-800 if you include a girdle which you should as it will add strength to the rear end. Not so much needed for the 4.10's, but if you start bumping up the hp you will be glad to have the extra insurance.

You will need to get a tune, and recalibrate the speedo(if the tune does not cover it) as it bumps the MPH by about 8-10mph. MPG wise not really seeing alot of difference though at 80mph you are spinning some 240-260 rpm's more than stock( I think its that much...you get the idea though)

Ford Racing gears tend to whine, but thats a sacrafice you make for being able to really dig out of a corner or stop light when you need too. There are quiter 4.10's from what I hear, but as you get quiter, they cost more.

When you do the replacement you will have to replace the axle bearings( I think that what you call them....when Scott L. @ Team Toyland did mine, that what he said is the right way to go, and he knows of what he speaks) $50-100 depending on where u get em.

All in all though, a great mod, and worth it... Good luck:beer:

[RF Overlord]

Hauser, don't even consider 3.73s...there is so little difference from the factory 3.55s that it wouldn't be worth the time or money. 4.10 is by far the most popular ratio as it makes a big difference in the way the car launches and drives at lower speeds, yet doesn't have a big MPG penalty. Some members here have gone to 4.30 and a few even have 4.56 gears, but I wouldn't recommend those if you do any significant highway driving.

As far as noise, my FRPP 4.10s are still silent after almost 18,000 miles of use. Some of that may be due to the Motorcraft 75W-140, which is what Ford installs with the axle TSB.

You will need a tune to correct the shift points (which will now be too low) and the speedometer (can't just change a gear like the older Panthers), but a tune is one of the first mods you should consider anyway, as it really wakes the car up.

[Hotrauder]

You are reading from the bible, Bible by Bob ^^here. It is the gospel! Once those mods are done put the Trilogy on. Dennis

[Seneca]

410's And a good tune is a great place to start you wont be sorry :D

[FordNut]

All the above, but you will probably need axles. Most leaking axles are associated with the bad axles which were installed in early production Marauders. There is a repair kit which has both axles, bearings, seals, fluid, etc.

[RUSTY]

My Wife went on a road trip and when she came back the right axle seal was leaking. Ford opened up the rear and changed the seals and the parking brake because it was oil soaked. I gave them the tsb about the axle but they said they were ok. If you get your mechanic to change the seals, make sure they are careful putting the axles back in because you can damage the abs pickup.

[GreekGod]

...If you are going to change the ratio, you should go to 31 spline axles and a locker differential at the same time. Some will tell you the 28 spline axles are good enough, but Ford went to the 31 spline shafts with the SOHC 4.6, so that's telling me something.

[SC Cheesehead]

You are reading from the bible, Bible by Bob ^^here. It is the gospel! Once those mods are done put the Trilogy on. Dennis

Dennis,

Ah, you blower guys! Always trying to get us normally aspirated folks to turn to the dark side!:nono:

Anyway, keep talking, I LOVE the temptation! :D (and who knows, maybe one of these days.....)

SCCH

[Mike Poore]

Don't forget the Shiney Hiney! :D

[fastblackmerc]

I'd go with the 4.10's and get the Ford Racing gears (you'll have less noise and less problems adjusting them). You'll also need lube, I used Redline, pinion and side bearings, pinion seal, either a rear end gasket or RTV, new axle seals since yours are leaking and make sure you check the axles and bearings. You need a tuner to adjust for the new gears. You'll see about 200 - 250 RPM increase at speed and you'll lose about 1-2mpg, but the tuner and gears are well worth it.

[BigPimpin]

IMHO I would not put a locker in. I put a detroit locker in my Gen1 Lightning and that thing is noisy. People warned me before I put it in about the noise but I didn't listen. So that's a pickup truck making that much noise I can't imagine what it would be like inside a car. I do agree with the above that if you're doing a gear change that you should go ahead and replace all the bearings and seals. It's not that expensive and it's good insurance. The 4.10's won't whine if you get them lined up correctly. Also, I purchased Motive Gear ring and pinion for my truck and paid about the same as the FRPP and my understanding is they are stronger. Good luck with whatever you decide to do and let us know the results.

If you do decide to go with the 31 spline axles I have a 8.8" 31spline posi-track unit that I'm not doing anything with. It probably needs clutches but my understanding is they are not that expensive.

[MarauderMark]

Don't forget the Shiney Hiney! :D

Ha ha ha Thats rite Mike:up:

[wchain]

4.10s would be a good choice. I think the 'seat of the pants feel' of 3.73s is not worth it.

Now if you're coming from the 2 Valve, 2.73 Equipped Panther, then yes, 3.55 or 3.73s would be awesome!

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[Hauser717]

Thanks for all the replies and good information guys. My old man's mechanic is going to do the work and he's trying to talk me out of the 4.10s. So I have more pondering to do. I'll post what my final decision will be once I figure out what it will be.

[KillJoy]

+1 on 4.10's :up:

The car should have came with them, along w/ a Tune (like DR's or Lidio's).

If your mechanic can justify, in a 4400lb car, why going from 3.55's to 3.73's is a better choice than going to 4.10's, I would like to hear it.

I also agree....you will MOST LIKELY not get the kick in the pants difference hopping up to the 3.73's.

Just MY thoughts ;)

KillJoy

[Hauser717]

He is trying to talk me into staying with the 3.55s. He agrees that the 3.73s are useless, but he is arguing that the 4.10s will reduce milage and top speed more than what I would want.

[KillJoy]

He is trying to talk me into staying with the 3.55s. He agrees that the 3.73s are useless, but he is arguing that the 4.10s will reduce milage and top speed more than what I would want.

Agreed. If you DO NOT change your driving habits, your milage will drop 1-2 MPG over all. It you get in to it more.....well.....it will be a more :D

As for top speed, if you must go 160's instead of 140's, then keep the 3.55's :D

KillJoy

[RF Overlord]

As for top speed, if you must go 160's instead of 140's, then keep the 3.55's I agree with KillJoy...for that matter, if top speed is your primary concern, then you should switch to 2.73s. However, if you want a car that is MUCH more fun to drive, both around town and on the highway, then 4.10s are "teh win"...