I have nice '95 1500, the differential's been making noise for quite awhile, I wanted to get it fixed, long story short,

after getting some auto shop quotes, I had a friend of a friend rebuild it, I said as long as we're doing it, rebuild everything,

went and picked it up at his 'shop', he showed me some big gears he'd replaced ( sorry I know nothing about rear ends), and 6 bearings,
I drove home, oh did it sound quiet :-)

the next day I'm on the interstate, something doesn't seem quite right with the tranny, or something?, I glance down down to check my speed, and I'm going almost 90 mph! H C! I slow down to 80 real quick but notice I'm now going with the normal traffic flow,
which should be around 65 mph or so,

I know That Ain't Right!

then I notice my RPMs are a bit higher then they should be at highway speeds ..

so what did he do do it, obviously replace a wrong gear ratio or something?

 

Haha he must have put deeper gears in, so yes they are a different ratio. If you're truck is 4wd don't use it unless he did the front too.

 

depends what gears he put in and what tire size your running. its kind of vital that you find out

 

Darn, he hasn't returned my call yet.

yes it's a 2 wd automatic, will it hurt to drive it?

 

If it isn't making any rude noises, and the only difference is RPM vs. Speed, then no, won't hurt anything.

 

well .. he said he just needs to replace a gear,

in the speedometer? Doesn't seem right to me, I can feel something different in the transmission, or what I'm feeling, is the wrong gear in the rear end, not the speedometer?

 

he might of put some 4:10s in, if you have stock 225s or 245s, your speedo is going to be way off and your going to have some serious torque opposed to 3:55. if your tranny is shifting well then your in the clear. youll need a new gear in your tranny to recalibrate the speedo.

 

sorry but I don't know any of that r end lingo, never took one apart and don't know the parts,

shouldn't he put something back in that matches what I had? Is it my imagination or has my top speed at a certain rpm been reduced a little bit?

 

depending on your tire size and if you plan on going larger tires maybe keep the new gears? Also could bring your truck in and get the speedo re calibrated.

 

He should have put the same ratio in as was there, unless he discussed it with you. Depending on how you use the vehicle, the new ratio could be beneficial. You'll have to find out what ratio he installed. Count the teeth on your old gears and divide the larger number (from the ring gear) by the small number (the pinion) to find the original ratio. It could possibly be stamped on the gears also.

Lower gears have higher numbers. He probably used 3.73:1 or 4:10:1 gears. With the 4.10s the pinion (the driveshaft) makes 4.1 revolutions every time the ring gear (the tires) make 1 revolution. Lower gears increase torque to help get you moving or haul a lot of weight (do you pull a trailer often?). Your top speed will decrease because the engine is spinning faster at the same MPH.

You can change the speedometer gears to make the speedo read correctly with the new gears. You have to decide if you like them or want your old ratio back.