How much difference do gears REALLY make?
- Thread starter The Dan
- Start date
You pull the whole pumpkin outta the rear end housing first... Once its out, you tear it apart and put the new gears and bearings in and either reuse or replace your differential. But it requires some specialized tools and more likely than not some experience at it to get it perfect. I had an old drag racer buddy that has a machine shop assemble mine for me, I took him the gears, the rebuild kit, the locker, and my core pumpkin, and he charged me 100 clams to put it together and set the gears up, did a hell of a job, doesn't whine at all.
You won't find a 3.55 set for a 9", they don't make 'em, but they make a 3.50 set that can be bought from just about anywhere, Summit and Jegs both sell gearsets from various manufacturers. IIRC the 3.5 gearset is about the least expensive one they sell.
You won't find a 3.55 set for a 9", they don't make 'em, but they make a 3.50 set that can be bought from just about anywhere, Summit and Jegs both sell gearsets from various manufacturers. IIRC the 3.5 gearset is about the least expensive one they sell.
taylor4g63
Founding Member
I bought a whole, webbed, 3.55 pumpkin with an auburn posi in it off ebay for $450 shipped or so for my 8 incher. One of the best investments i've made for my car (except for the gas milage, EFI is next to help with that though).
reenmachine
20+ Year Stangneter 
http://www.currieenterprises.com/monkeyman08880 said:
Most people just replace the whole pumpkin with a professionally rebuilt one and use the old one for a core. The whole swap can be done in a few hours if you've never done it before and have a couple of jack stands and basic hand tools. A good hand could probably do it in an hour.66stangmeister said:
blue66tang
Founding Member
blue66tang
Founding Member
The vid is with my 8" 4.11 limited slip diff, and 4 people in the car.
http://www.we-todd-did-racing.com/Hosting/showimage-fr-main.wtdr?i=Mzk4MjQ1NnM0MTNkZmQzMXk1NDE=
The pic is the same rearend a couple days later, thanks to a hard 2 gear shift and yet again 4 people in the car. http://forums.stangnet.com/attachment.php?attachmentid=23967
Now i have a 9" 4.30 gears and detroit locker. Havnt driven it enough to tell you if i like it though.
guess the vid link didnt work.
http://www.we-todd-did-racing.com/Hosting/showimage-fr-main.wtdr?i=Mzk4MjQ1NnM0MTNkZmQzMXk1NDE=
The pic is the same rearend a couple days later, thanks to a hard 2 gear shift and yet again 4 people in the car. http://forums.stangnet.com/attachment.php?attachmentid=23967
Now i have a 9" 4.30 gears and detroit locker. Havnt driven it enough to tell you if i like it though.
guess the vid link didnt work.
cornholio
New Member
3.25's, if you are looking for a "kick in the pants" is still too conservative. Compinsate for you tranny (overdrive?) and your wheel size (16" or higher go for more aggresive gear). You mentioned not to much highway time. If so sneek a better gear in there (i.e. 3.89) for sure/no doubt. If you do 3.25's you will be changing them again, that is again if you are looking for the acceleration it sounds like.
Best bet, find a 9" out of a 77-80 Lincoln Versaille. Direct bolt in with disck breaks, no mods needed to mount, zero. Just need to shorten you drive shaft by about an inch and a half or so. It will never,never,never, break.
Good luck.
Best bet, find a 9" out of a 77-80 Lincoln Versaille. Direct bolt in with disck breaks, no mods needed to mount, zero. Just need to shorten you drive shaft by about an inch and a half or so. It will never,never,never, break.
Good luck.
66P51GT
New Member
Wheel height has no affect on gear selection. Tire height does however.cornholio said:
Example
A typical 245x45x17 tire has a 25.68" tire height. (17" Rim)
You can purchase a 26x9.5x15 slick that has a 26" tire height. (15" rim)
mdjay
Premium Sponsor
I didn't see the trans you have but I concurr for the 3.55 gear being a nice street gear. You don't want to go much higher unless you have a 4-5 speed and a good high rev'n motor...
mdjay
Premium Sponsor
Oh, don't go with the limited slips. I can't tell you how many people call with (only one wheel is spinning) after 3 mos!!!
65fastback2+2
New Member
rhurley said:
65/66 the rear end is 2" wider. You can compensate this with different backspacing wheels and it wont make much of a difference.
67/68 it is a direct bolt in.
All you have to do is reweld the spring perches.
Just get one outta a 96-98 Explorer/Mountaineer 5.0. They have been shown time and time again to match a 9" in performance.
66P51GT
New Member
I thought the Explorer RR had an offset pinion. So, you have to shorten only one side to get the width correct and center the drive axle.
cornholio
New Member
Your example goes from a street tire to a tall slick. My reply was directed towards a street application. A 285x45x15 wheel/tire next to a 285x45x17 wheel/tire and the difference is approximately 1.5 inches. Same tire, with different wheel.
Your statement is correct but I don't believe applies to the owners original post in regards to a street application.
Your statement is correct but I don't believe applies to the owners original post in regards to a street application.
Route666
Active Member
If you change tyre height to compensate for diff gears, you may as well do neither, as one will give you more leverage in every gear, and the other will remove it from every gear. The only way to not have to compromise with big ratio diff gears is OD like you said.
Route666
Active Member
cornholio said:
But it's not the same tyre, one is a 15, and one a 17. Sure you changed the wheel size, but only to fit the tyre to the car. Wheels do nothing except provide an interface for the tyre to mount to the vehicle. Sure they look good, but that's subjective and unimportant to the function of the vehicle.
66P51GT
New Member
This is going way off topic here...
My example was just that. I only used these tire sizes because I know the dimensions off the top of my head. It was not meant to compare a racing tire to a street tire. So with that in mind another example would be a 285x35x18 tire which also has a tire height of 25.68". In your example... there isn't even a tire made that is 285x45x15, nor would a 285 have a prayer to fit on a '65.cornholio said:
True if you ingore weight, sidewall height, and vehicle purpose such as performance street, drag, autocross, or open track. The only non performance categories are bling & show.Route666 said:
Route666
Active Member
66P51GT said:
Weight is a side-effect, if wheels weighed nothing everyone would rejoice because the wheels PURPOSE isn't to have weight, it's to mount the tyre to. If it is lighter good, but weight is only a side-effect of it being there.
Sidewall is not a property of a wheel, it is of the tyre. A bigger wheel just allows you to have a smaller sidewall and maintain the same overall height.
What I was getting at was that the tyre is what changes leverage, not wheels. More importantly though not to use taller tyres to combat higher diff ratios.
I see your point though, ultra-light wheels won't work in 4WD or heavy load capacities, and tough steel wheels wouldn't be the best for racing. I was looking at the wheel from a pure design view, ie, the theoretical wheel - no weight and unbreakable.
one2gamble
Founding Member
66stangmeister
New Member
same here d00d, lol. 
how much those those usually run? I have a 9 inch at the moment, but it's not posi trac. which annoys me
how much those those usually run? I have a 9 inch at the moment, but it's not posi trac. which annoys me 
