RPMS at what speeds?

5th is overdrive on the 5M.

 

Ohh ok and I’ve checked speed on one of those speed monitors and it’s only like 1 or 2 mph off

 

So your indicated speed is right.

You just need to find out why the RPMs are so high.

When you’re in 4th or 5th, what happens when you floor it? If the RPMs go up and your speed doesn’t increase, your clutch is slipping.

 

When I floor it in 4 th and 5th she’ll speed up

 

Maybe the transfer case is in low range...

 

You mean like 4 low?

 

No. It’s 2.28:1 and 70 mph wouldn’t be possible.

 

That was kinda my thought too, but idk if you could go that fast in 4lo even in 5th without being on rev limiter.

How are you sure it has 4.10's? Just by the door code sticker? Or actually counting spins of the driveshaft? Has the truck always done this or is it a new issue?

Basically what I see, is either the tach is off (doubtful because you said the motor is screaming) the clutch I wouldn't think is slipping because you'd smell it and it'd burn up in a few miles as people have already said. So you take those two things out, and being a stock 5spd with 4.10's it's impossible for it to be doing that rpm at that speed. Either you're not in 5th or the truck has been regeared to a lower, numerically higher rear end

 

No way you could hit 70mph in 4lo lol...I think I've gotten up to 40 mph in 4lo and 5th and was pushing 4k rpms. I dunno maybe it's possible but I feel like you'd definitely know it

 

I agree

 

Yep, I didn’t like going 35 in low range / 5th. It’s eqivalent to 80+ in high range.

 

Check your gear ratio like this

http://www.how-to-build-hotrods.com/gear-ratio.html

Also, if you are sure the clutch is not slipping, there are online calculators that factor all elements. It will be pretty accurate.

 

Is that gauge cluster from a 4 cylinder by any chance?

 

I know it’s a 4:10 bc I got the rear axle and front diff out of a newer 1st gen Tacoma and swapped both with mine and the sticker on that truck was 4:10 I don’t think it had been regeared before I pulled it bc the donor truck was bone stock but i haven’t really checked but I’m sure I’m in 5th gear believe me I know I am

 

No it was the v6

 

Yep I’ve done this before bc when I bought my truck the previous owner had two different front and rear gear ratios

 

What was your cruising RPM like before you swapped them? Given the info I'd say the new ones you swapped in must be a lower ratio. Because if it's a v6 cluster that is reading correct, and you're in 5th, is impossible to be doing that RPM. It would be really weird if you got diff's out of a stock truck that were regeared lower, but that's the only thing that makes sense to me.

 

Well the first rear axle was 4:30 with with something else in the front I can’t really remember how it crused but I know that a buddy of mine that has practically the same truck except 98 pointed it out while he drove it that it reved high while cruising doing like 60 to 70 when he’s truck was a lot smoother and lower rpms then I put a temporary 4:10 bc the other rear end had bad seals and it felt a little different not a whole lot but it’s been the same since i swapped both front and rear

 

It really sounds like your rear diff is not 4.10.

 

I have 4.10 gears and 5 speed manual with 31" tires and my tach reads exactly 2500 RPM at 70 MPH.