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Discussion Starter #1
So I have been on the fence recently about what I want my next mod to be. First I was thinking a BBK throttle body, but after hearing from some people on the forums, there are probably other places to put my money first. I was thinking 4.10 gears and a limited slip differential. I'm new to the whole mustang scene, so I just know the very basics of what each of these will do for my car. 4.10 gears will make the car faster off the line, but will hurt the mpg (which isn't really a big deal to me), correct? And the limited slip differential will give me better traction and both tires will spin as opposed to just the right rear? That is about the extent of what I know about these two mods. Any other information about these mods would be greatly appreciated, or any other suggestions as to what I should put in my car next would also be great. Thanks Everyone! (I love this site...:bigthumbsup)
 

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You hit all the high points. You'll sacrifice a little mileage and top end speed but it's worth it.
 

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Discussion Starter #3
Thanks stl. One other question regarding the gears. Is there anything else you have to do after the gears are installed? Any sort of tuning involved?
 

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Thanks stl. One other question regarding the gears. Is there anything else you have to do after the gears are installed? Any sort of tuning involved?

I do beleive you will have to go through a break in period and Definatley get a tune for them. If you dont get a tune your mph will be way off
 

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If you have a brand new ring and pinion gear set installed then you'll face some heat cycles and a break in period before you can romp on them. The heat cycles usually consist of 3 15 minute drives at highway speed and letting the car cool down completely in between each drive. This helps work the last burrs and garbage off the gears and allows them to develop a 'pattern.' The break in period is just taking it easy for the first 500 miles or so.

Or you could get a lightly used gear set and pay less and peel out of the parking lot when you pick your car up from the gear shop. :gringreen
 

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Discussion Starter #7
I was checking around some of the older threads, and it got me thinking about possibly swapping out the 7.5 rear end for the 8.8. What do you all think? I definitely do not have enough power to do any damage to the 7.5 right now, but I am hopefully just getting started with my mods, so maybe someday I will have enough power where a swap would be necessary.
An 8.8 rear end comes ready with the lsd and optional 4.10 gears, correct? I'm guessing it would probably be more fiscally responsible just to get the axle swapped out now if I hope to put more power into it down the road? How much power can the 7.5 axle take, roughly? Any opinions on the matter would be greatly appreciated. Thanks again!
 

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Swapping the rear ends is a popular option and you can get them already equipped with the gear ratio that you want. It costs a bit more though. I think the 7.5 can handle a bit of abuse; there are some V6 guys here that are blown. And you could make the axle swap in a garage if you really wanted to.
 

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I was checking around some of the older threads, and it got me thinking about possibly swapping out the 7.5 rear end for the 8.8. What do you all think? I definitely do not have enough power to do any damage to the 7.5 right now, but I am hopefully just getting started with my mods, so maybe someday I will have enough power where a swap would be necessary.
An 8.8 rear end comes ready with the lsd and optional 4.10 gears, correct? I'm guessing it would probably be more fiscally responsible just to get the axle swapped out now if I hope to put more power into it down the road? How much power can the 7.5 axle take, roughly? Any opinions on the matter would be greatly appreciated. Thanks again!
Going with an entire 8.8 from one of those "take off" places would be a great idea. I have seen them with 4.10's for about $600-700. That is about the cost of a gear and install
, let alone a LSD and a bigger rear end. You should be able to find slightly used axles for almost nothing too. I know I sold mine for $75.

The 7.5" rear end is a lot stronger than you would be lead to believe. Back in the day (mid 80's) there were a lot of 5.0's with a 7.5" rear around, I had a couple myself. I have gone mid 12's with slicks on a 7.5" rear end with no problems. With 8.8 take offs so cheap I wouldn't think of building up a 7.5" rear though.

Is your car an auto or a 5 speed?
 

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Discussion Starter #10
That's sort of what I was thinking. The cost of the gears, differential, and install would probably be about the same as just getting the whole rear end. And this way I get a stronger axle too...:bigthumbsup

Mine is an auto...
 

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If you can measure the height of one of your rear tires I can tell you what your top speed will be with a 4.10 and what RPM's you will be at while cruising at 75mph on the freeway.
 

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Discussion Starter #12
Ok, I am a mustang noob here. I just measured from the ground to the top of the tire. Is that the correct way to do it? (Measuring the height of your rear tire doesn't sound that hard, but I could still screw it up :headscratch:)

Haha, from what I measured, it was 26 inches top to bottom...
 

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Ok, I am a mustang noob here. I just measured from the ground to the top of the tire. Is that the correct way to do it? (Measuring the height of your rear tire doesn't sound that hard, but I could still screw it up :headscratch:)

Haha, from what I measured, it was 26 inches top to bottom...
Yup, that's it.

I am assuming you have a 5 speed here (it's a little different for an auto)

With a 4.10 gear your top speed will still be 157mph

Your RPM's at 75mph will be 2850

If you do a lot of driving on the freeway at 75mph that could be a little anoying. But if you want to cruise at 65mph you will only be spinning 2500rpm's

If you don't just cruise on the freeway very much you will get better gas milage in town with the 4.10 and it will get a little worse on the freeway.

Here are some other gear ratio's and their effects:

3.55 - 75mph @ 2500 rpm
3.73 - 75mph @ 2605 rpm
3.90 - 75mph @ 2725 rpm

I would go with the 4.10's and a 100hp shot of N2O:bigthumbsup You could pound on unsuspecting GT's all day long. And you would be killing most ricers
 

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Discussion Starter #14
Thanks sqidd, I think I am going to go with the 4.10's, as only about 20% of my driving is on the freeway. Do you know how much of a difference changing the gearing will actually make for, say, 0-60 time? It's definitely enough to feel it when you give her some gas?

And killing ricers is my main objective. :D
 

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Thanks sqidd, I think I am going to go with the 4.10's, as only about 20% of my driving is on the freeway. Do you know how much of a difference changing the gearing will actually make for, say, 0-60 time? It's definitely enough to feel it when you give her some gas?

And killing ricers is my main objective. :D
I am doing the 8.8 4.10 swap as soon as I get 1200$ :D
From what I have heard (from people with 4.10s) they make a HUGE difference. I cannot wait to get mine. You will probably be able to pull on a gt off the line as long as she is not modded :scratchchin

anyone got ideas on what kind of rpms id run at 70 mph with 18 or 19 inch rims?
 
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