Well i just ordered 4:10 gear set for my 98 4.6 XLT
The shop will install them on wensday.I understand the truck should turn around 2300 rpm on the factory 29" wheels @ 70 mph?
What is the best brand of oil to get for the breakin keeping in mind i will have an open carrier(non LS) until i can get a tru-track in a month or two.I forgot to order the gear oil from Richmond!
I'm also told Richmond Gears are loud in comparison to other brands so if anyone can elaborate it would be appreciated.
How far off will the speedo be and what gear will i need to fix it.
Heres an article i have for the break in.
http://www.4x4now.com/gt0999.htm

 

Picked up the gears and they turned out to be Motive.The instructions say they have been pre lapped.Does this mean broken in?

 

I have the same setup. It's been a while, but I think that you will need the 23 tooth vss driven gear. That is probably as close as you can get - maybe 3-4 mph off at 60 mph.

There is a calculator here, as well as the gears.

http://www.transmissioncenter.net/sp...___va.htm#ford

 

The only way to get around the break in period is to blue the gears and adjust everything until you get close to 100% engagement on all teeth.

 

I was told to take it easy - and no towing - for the first 500 miles.
Then change the fluid and you're all good.

A few others were also given similar advice.
Seems reasonable, but I don't know if it's universally accepted as the "right" way.

When in doubt, go a little conservative, then you minimize the chance of "oh ***** I wish I'd done things differently" later on.

 

I would definitely make sure to go through the break in period of 500 easy miles then change out the fluid also.
I would rather be **** about performing the break in period than getting anally raped by a mechanic to replace the gears again.

 

When I had my gears changed in my 97 F150 the shop used US Gears.(8.8 differential) The shops break in procedure was;
Do not drive more then 10 miles over 50 mph for the first 100 miles.After each 10 mile drive pull over and let the differential cool down for 30 minutes.After the first 100 miles drive normally,but no towing until after 500 miles.They used conventional fluid for breaking in,80W90,but said to use a 75W140 synthetic when changing it at 500 miles.

BTW,it was a differential only shop that did my work! They choose not to use Motive gears due to them making too much noise!
Heres a good break in procedure;
http://www.4x4now.com/gt0999.htm

 

Wow different truck!
The shop i went to does mostly high performance and drag cars.Basicaly told me to get lost the last time i went in to ask about having it done.
This time i was sent there by the owner of the local speed shop and got probably the best service I've ever had anywhere.They even took the truck out and started the break in for me.
The motive gears make no noise and the magnaflows sound far better.
They told me that it was like ice driving the wet roads on the test drive and advised against installing the factory-tech b plate until i get the true-track.
I've had a Grand National and a few modified mustangs and find the trucks drivebility with the 4:10, gears magnaflow,AF1,fou1 factory tune,and factory tires almost perfect for a daily driver.
Probably have the B plate installed in the medium or light shift setting as a hard shift might be a little too agressive.Wont know until i can get on it in 500 miles and figure out what the gears did to my shift points. Any idea how far off the speedo is going 3:55 to 4:10?
Thanks again for all the information just waiting on a new speedo gear.

 

Your speedo will be about 15% off...

 

You nailed it but generally speaking your gears should be fine after the 500 mile mark. i would use this rule on any gears. As for best gear oil. Royal Purple will cost you a little extra but help the gears run a ton cooler and helps them produce a much longer life!

 

Matt I'm very interested to know what happens with your MPG. I'm debating on 373 or 410s. Please update us

 

Motive is a good gear, we generally use Yukon here.

Matt you should have waited until you could get the truetrac at the same time, labor should have been the same. Now you have to set the gears up again and pay probably the same amout of labor to install the truetrac as you did with the gears.

Richmond gears are generally softer which allows them to flex under high hp situations and flex so that they don't break. However they wear faster.

We generally stay away from Richmond and Genuine gear.

 

Both the transmission and speed shop said the true-track is basically bolt on and they will not have to reset the gears.Installation will be quick and easy they said?Guess i'll find out soon enough.
It will be a few weeks until i get the speedo and odometer fixed and the break in done.Then i will figure out the milage.
cheers