Ford Mechanic? Specifically rear end gears

Postby **RX-7 Chris** » Thu Feb 03, 2011 9:14

this isn't really for the 2011 mustang but it should give you an idea: http://www.musclemustangfastfords.com/tech/mmfp_0805_top_10_low_buck_mustang_parts/index.html

roninsoldier83 · Postby **roninsoldier83** » Thu Feb 03, 2011 9:14

Seriously, with 4.10's your car is going to have gearing closer to a MS3/MS6 or my old STI.... to me, for a daily driver, I prefer the longer gears in my BMW over my old STI or MS6's gears... if you're into drag racing, having to shift into 5th will negate a portion of the newly found acceleration in the 1/4. I don't know, if it was me, I might just wait until someone on a forum with stock 3.73's swaps over to 4.10's or something to that effect and pick up their stock 3.73's dirt cheap. To me, I can see why Ford would offer the 3.73's as an optional read end, as they would appear to be a very good compromise, and let you wrap out the 1/4 mile in 4th.

That's just my thoughts though... but since you're obviously not concerned with a warranty, my thoughts would be maybe hold off on the gears, put a few breathing bolt-ons on the car (intake, exhaust, maybe a decent set of headers), tune the bugger and see if you're still yearning for the additional torque after that.

Just my $.02

erod550 · Postby **erod550** » Thu Feb 03, 2011 9:14

The gears themselves are only about $160. It's the installation kit, replacement pinon bearing, and the labor to have it done that will be the bulk of the cost. So just finding someone's leftover 3.73s for cheap won't save me all that much.

The gears will probably come after the intake/tune and catback which I'm doing no matter what. After that, I'll decide if I still want to do the gears or not.

coloskydiver · Postby **coloskydiver** » Thu Feb 03, 2011 9:14

Mustang Motor Sports here in Denver is an awesome shop and would highly recommend them. They did some work on my Monster Miata and know a couple of guys that work there. Ask for Greg. PM if you want their number

ecam8000 · Postby **ecam8000** » Thu Feb 03, 2011 9:14

In the days of direct drive, I'd say the 4.10 are a bit steep (though I lived with some 5.14's in a 68 Mustang). I've not seen the specs but I'd bet that 5th and 6th are both overdrives. I think you'd be fine with the 4.1 gears. But unless you are into the tenths saved at the drag strip.......if it were me, I'd stay with the 3.55. You bought it, it is your call.

I do want to see that thing at the autocross. That is one of my dream cars (the wife doesn't have the same dreams).

Elite130 · Postby **Elite130** » Thu Feb 03, 2011 9:14

If you are willing to travel, try Scott at P&P Performance. He is located in Strausberg (30 miles east of Denver on I-70). He does awesome work. He works on a lot of Mustangs and does great work for a great price.

As for gears...go big or go home. On my 2002 GT, I went 4.10's and never regretted it for a second. 1st is short, but it pulled like crazy through all gears. The 4.10's kept you above the "lugging" part of the power curve. You can always find the right gear. A set of gears make the car amazingly different. Have you checked out all the Mustang forums? What are they all putting in the new 5.0's?

If you want...check out ColoradoStangs.com it is an awesome Mustang group (I've been a member since '02). They are based out of Denver, but there are lots of CS stangers.

Oh...one more thing...don't go used gears. Buy new. The used gears would have a pattern worn into them that once it is set into the gears, odds are they will whine if they are installed in a different differential and set up different. It just isn't worth it. Especially on a nice, new 5.0. The gears I always used was FRPP, they never whined. Richmond always seems to whine and Motive are hit and miss.

Good luck!

erod550 · Postby **erod550** » Thu Feb 03, 2011 9:14

Thanks for the tips Elite. I plan on buying new FRPP gears if I go through with this.

Almost all the 5.0 guys that I have seen are using the factory 3.73s. I would have preferred to just get those from the start but the only 3.73 cars around here were base models without the Brembo package which I really wanted, so I had to settle for the 3.55s since this car had all the other options I wanted.

4th and 5th on the '11 6-speed are identical to 3rd and 4th on the '10 5-speed. The individual gear ratios are...
1 3.66
2 2.43
3 1.69
4 1.32
5 1.00
6 0.65

compared to the 2010 and earlier 5-speed...
1 3.38
2 2.00
3 1.32
4 1.00
5 0.68

Postby **RX-7 Chris** » Fri Feb 04, 2011 9:14

so why not just go with the 3.73?

My Galaxie is running 3.88 with a 390 and a C6 auto. I never liked how short 1st is on that car. That car came stock with 3.00 so it was a big jump. The best for that car would be 3.55 since it is suck a big motor. Smaller motors do better with lower gears. I just think 4.10 will get old for you. If it was my car, I'd go with 3.73. It gives you the best of both worlds. If the car was just a weekend drag car, I'd say go lower than 4.10.

erod550 · Postby **erod550** » Fri Feb 04, 2011 9:14

I think the 3.73s are the most common because it's the lowest gears you can get from the factory, so they are easy to get because you can just get them on the car to start with. I just don't think the difference between 3.55 and 3.73 will be enough to warrant the cost of switching. Like Elite said, go big or go home, lol. I'm probably just going to do the bolt-ons and then drive it for a while like that. Do a few runs at the track, go through the whole summer and see how it feels. If by next fall I am still feeling like it needs more, then I will look more seriously into the gear swap.

AIM WO4 · Postby **AIM WO4** » Fri Feb 04, 2011 9:14

I think my '88 Stang had a 2.73 rear! I used to drive around at over 70 MPH in 2nd gear. I could smoke the tires form a dead stop. :eek:

roninsoldier83 · Postby **roninsoldier83** » Fri Feb 04, 2011 9:14

erod550 wrote:The gears themselves are only about $160. It's the installation kit, replacement pinon bearing, and the labor to have it done that will be the bulk of the cost. So just finding someone's leftover 3.73s for cheap won't save me all that much.

The gears will probably come after the intake/tune and catback which I'm doing no matter what. After that, I'll decide if I still want to do the gears or not.

Oh yeah, I almost forgot how stupid cheap and readily available gears for a Mustang are haha! Most of my cars have either been AWD or RWD imports... most people don't touch AWD final drive gears, as it gets very costly and labor intensive, as it involves not only changing out gears in the rear diff, but also ripping apart the tranny & replacing the gears in the front diff as well. Some cars (like the older 5-speed WRX's) also involved having to take apart the transfer case and replace the 1:1.1 step down gear with a 1:1 ratio as well.... VERY expensive, and much more of a pain in the *** than just pulling apart the rear diff on a RWD car.

The only car I've ever owned that I considered swapping rear end gears out on was my old 350Z... but the cost of swapping gears on a car with an R200 rear diff is a LOT more than it is for a Mustang!! Haha! Or at least it used to be (haven't checked into it lately). Sometimes I forget how cheap FD gears are on domestics lol.... in which case, I'm with you, just go new.

However, I still don't think 3.73's are a bad idea. 4.10's would be better for autoX or road racing, but I'm not a big fan of shifting into 5th in the 1/4 for a car primarily used for drag racing, and I prefer taller gears for my daily driver as well, but that's just me.

IMO, wicked short gears are great for autoX cars, as well as cars with a fairly narrow powerband (turbo 4's or high revving motors), but on a 5.0 V8 I would think the car has enough torque at just about any RPM to stay well within the meat of it's powerband with slightly taller gearing haha.

That's just my $.02

Postby **RX-7 Chris** » Fri Feb 04, 2011 9:14

The gears for my rx-7 are between $500 and $750 for just the Ring and Pinion Set. My car came with 4.076 stock.

erod550 · Postby **erod550** » Fri Feb 04, 2011 9:14

My Miata has 4.30 stock. And the individual gears are crazy short on top of that. I'm turning about 4300rpm at 80mph in 5th in that car lol. But it still gets 30mpg

And yea, having to shift into 5th would suck. Especially because I miss 5th all the time in just normal driving lol. I'd definitely have to practice a hard 4th-5th shift or I'd lose a bunch of time at the end of the 1/4.

Postby **RX-7 Chris** » Fri Feb 04, 2011 9:14

what do you want to use the car for? I guess that is probably the first question that should have been asked.

ecam8000 · Postby **ecam8000** » Fri Feb 04, 2011 9:14

The car will be used to make the rest of us wish we had a factory 400 plus HP car that will cruise cross county in any heat and pull down some great mileage. And comes with a warranty!

Ford Mechanic? Specifically rear end gears

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