Break in period for gears?

**GottaHaveLS1** · 09-19-2007, 07:08 AM

I'm thinking of getting some gears next summer when I get the car back out. I'm thinking of 3.73 or 3.90 but i'll probably get 3.73 to keep the rpms down for when I "attempt" to get good mpg. There is a break-in period for gears right? how many miles do I have to go easy on her?

**SSwt00SS** · 09-19-2007, 07:32 AM

typically they say break in period for gears is 500 miles, then change the rear fluid and you should be good to go...

**GottaHaveLS1** · 09-19-2007, 08:17 AM

Originally Posted by SSwt00SS

typically they say break in period for gears is 500 miles, then change the rear fluid and you should be good to go...

Is it easy to change the rear end fluid on my own? Cuz I wouldn't have it changed when the gears go in (unless they have to) to save money. I would just do the fluid change after the 500 mile break in period. any recommendations on rear end fluid?

**SSwt00SS** · 09-19-2007, 08:20 AM

it would get changed when you do the gear swap. its part of the price. they will drain, swap gears, reinstall, and add new fluid. you dont want to re-use rear end gear...

you could do it yourself, but if you dont have the tools, place, time, etc to do it, it wouldnt cost much to have a shop do it...

someone else will have to chime in on what brand of rear end fluid to use...

**GottaHaveLS1** · 09-19-2007, 10:36 AM

Originally Posted by SSwt00SS

it would get changed when you do the gear swap. its part of the price. they will drain, swap gears, reinstall, and add new fluid. you dont want to re-use rear end gear...

you could do it yourself, but if you dont have the tools, place, time, etc to do it, it wouldnt cost much to have a shop do it...

someone else will have to chime in on what brand of rear end fluid to use...

Yea i gotcha. My friend knows a place where i can get them installed for $200 but i'll have to wait for spring. I'd like to do it myself cuz I don't trust shops

**Jays00ss** · 09-21-2007, 08:41 AM

Drive 15 minutes, Stop, wait at least an hour. Do that 3 times to heat Quench the gears. Then take it easy don't go over 60 mph for the first 500 miles and change your speed up. Then change your gear oil at 500 miles (I would suggest royal purple or red line 75w-90 no need for posi additive) then give her hell. Just my .02 worth, but do what ever the mfg recommends who you bought it from.
Also do not waste your time and money with 3.73 gears on a 6 speed. I have 3.90's and should have gone 4.10's or even 4.30's. My rpms only went up around 300-400 rpm on the hiway. If your going to swap gears make it worth it.
Also I wouldn't suggest a gear swap. Save your money for a Moser 9". the 10 bolt that comes stock is a pyle of crap. I am now saving for the 9" because I am afraid of running slicks.

**Jays00ss** · 09-21-2007, 08:49 AM

Originally Posted by GottaHaveLS1

Yea i gotcha. My friend knows a place where i can get them installed for $200 but i'll have to wait for spring. I'd like to do it myself cuz I don't trust shops

Do not attept to do the gears yourself. It is a painstakeing task that is a pain in the ass if you have never done it before. Any wrong set up (On the backlash) will have castistrophic effects on your rearend and you will lose all the money you just put into it. Paying someone that knows what they are doing to install your gears is well worth your piece of mind. It is one of the the only jobs I would recomend paying for.

**GottaHaveLS1** · 09-21-2007, 12:52 PM

Originally Posted by Jays00ss

Do not attept to do the gears yourself. It is a painstakeing task that is a pain in the ass if you have never done it before. Any wrong set up (On the backlash) will have castistrophic effects on your rearend and you will lose all the money you just put into it. Paying someone that knows what they are doing to install your gears is well worth your piece of mind. It is one of the the only jobs I would recomend paying for.

I meant to change the rear end fluid by myself. Which i'll probably end up doing after the first 500 miles. Looks like i'll get 3.90's... what's a decent brand to go with? how high will my rpms rise?
I really don't have the money for a new rear end. They seem to cost about a grand or more. I'm a broke college student... getting new rims and tires and the gears & install is more than i can afford for the next year.

**rc74racer** · 09-21-2007, 01:01 PM

Originally Posted by GottaHaveLS1

I meant to change the rear end fluid by myself. Which i'll probably end up doing after the first 500 miles. Looks like i'll get 3.90's... what's a decent brand to go with? how high will my rpms rise?
I really don't have the money for a new rear end. They seem to cost about a grand or more. I'm a broke college student... getting new rims and tires and the gears & install is more than i can afford for the next year.

Don't do 390s you won't feel much of a difference. I recently had 410s installed and they are great. I only lost about 1mpg and I can still cruise 75mph at 2000rpms.