Bid on gear swap
Registered User
Joined: Jul 2011
Posts: 19
Likes: 0
3.92s are a good upgrade from what you have, but at 80 mph they would yield about 2/10 of a MPG worse gas mileage than 4.10s according to my tire rotations per mile calculation and would go down as cruising speed decreases from 80. But that little bit of extra gearing may be the difference in the tranny staying in gear and searching for the right one in certain situations. If this is for OFF THE LINE performance only the numerically higher the gear, the better. 4.10s will get off the line faster than 3.92s, 4.56s faster than 4.10s and 4.88s faster than 4.56s.
His price is high and again like in your last post - YOU NEED TO KNOW WHAT LSD HE IS USING.
PLUS I am very familiar with Yukon, Precision, Genuine, Richmond & Motive gears and IN EVERY CASE the 3.92s are the same price as their 4.10s (and 4.56s for that matter).
Edit: I just did a search on a couple of my 4x4 specific forums and there is a little bit on the Sierra's. One guy says his 4.56s are noisy as hell (but this is probably a poor install). According the the Sierra website, they don't make a 3.92 for a Chrysler 9.25" rear but they make a 3.90, the difference in negligible.
The few places I can find that sell them list the same price for Chrysler 9.25" Ring & Pinion sets from Sierra from the 3.21s right on up to the 4.88s, so I don't know why he is charging you $100 more for the 3.90s over the 4.10s.
The most I can find on them is on the Jeep forums, the gist is they are bargain priced gears with prices rivaling the Chinese made stuff, but they are US made. They advertise US quality gears rivaling Motive at the price of "bargain" gear sets.
They are $200 gears, allow $100 for the install kit. IF he's using a true Detroit TruTrac then the going price for that is $500, so I come up with $800 in parts and I'm going retail, I'm sure he's buying wholesale. I dunno what clutch type LSD is $300 cheaper because the only other one I'd use is an Auburn and it's $400 ($100 cheaper).
In my experience, a mechanic who brags about how good he is, isn't for sh*t, but he might just be that good.
Find out SPECIFICALLY what LSD he's using. Be sure you are ok with the 3.90s and ok with over-paying for his supposed expertise cause that is about a $1100 job in my book WITH a DETROIT TRUTRAC.
GET EVERYTHING IN WRITING, if he's as good as he says he is, then he'll have no problem spelling out that if they whine in the least, he'll make it right at his cost!
Remember, after all is said and done, YOU are the one spending the money here. If you want certain brands and ratios it's your right to get exactly what you want...
His price is high and again like in your last post - YOU NEED TO KNOW WHAT LSD HE IS USING.
PLUS I am very familiar with Yukon, Precision, Genuine, Richmond & Motive gears and IN EVERY CASE the 3.92s are the same price as their 4.10s (and 4.56s for that matter).
Edit: I just did a search on a couple of my 4x4 specific forums and there is a little bit on the Sierra's. One guy says his 4.56s are noisy as hell (but this is probably a poor install). According the the Sierra website, they don't make a 3.92 for a Chrysler 9.25" rear but they make a 3.90, the difference in negligible.
The few places I can find that sell them list the same price for Chrysler 9.25" Ring & Pinion sets from Sierra from the 3.21s right on up to the 4.88s, so I don't know why he is charging you $100 more for the 3.90s over the 4.10s.
The most I can find on them is on the Jeep forums, the gist is they are bargain priced gears with prices rivaling the Chinese made stuff, but they are US made. They advertise US quality gears rivaling Motive at the price of "bargain" gear sets.
They are $200 gears, allow $100 for the install kit. IF he's using a true Detroit TruTrac then the going price for that is $500, so I come up with $800 in parts and I'm going retail, I'm sure he's buying wholesale. I dunno what clutch type LSD is $300 cheaper because the only other one I'd use is an Auburn and it's $400 ($100 cheaper).
In my experience, a mechanic who brags about how good he is, isn't for sh*t, but he might just be that good.
Find out SPECIFICALLY what LSD he's using. Be sure you are ok with the 3.90s and ok with over-paying for his supposed expertise cause that is about a $1100 job in my book WITH a DETROIT TRUTRAC.
GET EVERYTHING IN WRITING, if he's as good as he says he is, then he'll have no problem spelling out that if they whine in the least, he'll make it right at his cost!
Remember, after all is said and done, YOU are the one spending the money here. If you want certain brands and ratios it's your right to get exactly what you want...
Professional
Joined: Jan 2011
Posts: 226
Likes: 0
i agree with others, find another shop. if i were you i would find a local jeep club "we allways go to higher gears" and ask them who they use. as i also have a jeep, i would only use yukon top shelf gears. i also wouldn't go less than 4:10 and would consider 4:56, you can go to larger tires to bring rpms down. don't rush into this mod blindly, take your time learn all you can and pay for this only once as this is one mod that if it fails will leave you stranded!