Alright so Ive asked this question in the [past but I still haven't been able to solve my issue. and yes ive checked my tach connections and everything is fine. I am running an aftermarket Sunpro Tach and everything is wired right but I still dont know as to why my engine revs so high at those speeds..I got a T5 tranny with a 305 LG4 engine and even at 70mph its reving at arounf 4000RPM's. Earlier today I gunned it to 90MPH and I was already at 5000RPMS's so im pretty much limited to how fast I can go because Ill be red lining it by the time I hit 95mph.....

For the rear to my knowledge I know for a fact I have a non posi unit and I am about 95% sure I have stock gears...Anyone might know why this is happening...Or is this just how the car is??IM PRETTY PUZZLED ON AS TO WHAT IT MIGHT BE?

 

In what gear?
If you put the right numbers in
http://www.bgsoflex.com/rpmmph.html
here it will tell you what rpm you should be doing at what speed

About time you checked it out ; might solve all your guesses

 

is the tach set to "6 cylinder"?

 

Its simple math, there isn't going to be a "diagnosis" here....your either running 410 gears, or your not actually in 5th gear.
This is going on the assumption that some common sense has been exercised and your not simply trusting a cheap tach. I would hope you can hear and feel the difference between 5000rpm and 2500rpm without a tach.

 

Not really much else to say but this.

Bizarro explanations that are unlikely would be:
1. massive clutch slippage... MASSIVE.
2. 5th gear ratio is the same as 3rd gear.
3. 13 inch diameter wheels + tires.


Seriously man... does it SOUND like 5000 RPMS? Thats well on up there, you should know if it's really that high. Your engine shouldnt want to run much past that anyway.

Also, dont be an idiot and drive around at 90+ mph on the road.

 

Well Im not relying all my senses on the tach I can literally hear my engine roaring at those speeds even @ 70mph when im on the freeway I can hear 4000RPMS......so thats why when Im driving I rarely pass 70 just because of my rpms.

and the tach is set correctly.

 

and as for my tires and rims I have 245/60/15 on the back and 235/60/16 in the front.

 

going with infernal on this one...

1 massive clutch slippage

2 you are shifting from 4 to 3 thinking it is 5...

3 your tach is wrong and you dont know what 5k rpms sounds like...

or maybe the ring and pinion switched themselves for a set of 4.11s oh wait they cant do that! because you would have seen them pulling themselves out and it would have made a huge mess... they never remember to get the oil pan in before spilling the oil everywhere

 

Im not super familiar with T5 ratios... BUT....

If your 3rd gear is around 1.3 (pretty normal) AND you have 3.73 rear gears (unusual... but possible) you will be at 4000 RPMs at 65 mph in third gear. Do the revs go DOWN from 4th to 5th? It sounds liek you're in 3rd gear to me if what you're saying is correct.

If you're in 5th gear and it's around a .75 ratio (not positive on T5's, but it should be in that neighborhood), then your rear gears would have be OVER 5.xx to hit 4000 RPM at 70mph.

What is it doing in 4th gear? Is it possible your 5th gear is busted and its putting you into 3rd gear?

 

it wont engage a lower gear if 5th is gone... shifter will move into place but there just wont be anything there like neutral... or horrible noises before nothing is there.

maybe reverse lockout solenoid? no idea if it is possible

but to not notice the hugely jaring shift from 4 to 3 at 55+mph is harder to believe

 

Or he is actually doing the 160 MPH you get in 5th gear @5K with 3.23 gears BUT his speedo is only reading 90 MPH

 

A third gen V8 T5 has either .73 or .63 5th gear.

Besides what has been said, a V6 T5 is a possibility.

.63 and 3.73 and over 4000rpm is a lot more than 90mph.

A rear diff. fluid change is in order to verify gears there.

 

yeah its a rear gear, tach, tranny gears or massive slip but you would feel that! What speeds and rpms do you have in the other gears?

 

are you sure the speedo is correct?

 

this is easy to check- either do it the old fashioned way by checking the odometer against mile markers or do it the modern way and use a GPS unit or smartphone with a built in GPS and a speedometer app..

 

there is no way someone mistakes 160MPH for 90... especially in a thirdgen! if that is what happened please head to the nearest state trooper to hand in your license... hopefully you can do that without killing either of you...

 

Yeah i very much doubt the car would even go that fast! And if it did im sure if u go 70 in a 75 and you are flying by people like they are standing still you would know what the problem is. Along with the what is 5k in every gear does the car seem to be stupid fast off the line and you have to shift really fast?

 

honestly if you dont know what the rear gear is I would say someone before you just smashed so crazy gears in it!

 

Are the revs and speeds OK in other gears or is it just the one gear?

 

Even if he has a shorter .73 gear in it, to hit 4000 RPMs at 70 MPH means he has rear axle gear between 5.95 and 6.05. That's insane. I dont want to be too presumptuous but I cant even imagine ratios near 6.00 even exist for the 10-bolt...

 

Except if its a v6 tranny or if it had the tranny gears played with.

 

I imagine even a v6 transmission will have an overdrive gear that is less than 1.00. So even if we assume 5th gear isnt even overdrive, it's a 1:1 ratio like fourth gear, that means he needs a rear end ratio of 4.56 to get to 4000 RPMs. So we are looking at 4.56 as the lowest possible rear gear ratio he could have that could get these results. But in all actuality, even v6 T5's are going to have a 5th gear that is overdrive.

From a quick check in the T5 faq thread, even v6 t5's got either a .73 or .78 5th gear ratio, which puts us right back at a 6.00 rear gear. Thats clearly unlikely.

Although I do like the idea of a prankster setting the 5th gear ratios to the same as 3rd gear for the lulz.

 

So whats your idea that it is cause you havent givin any advice yet haha all im saying is that it has to have something with the gears if he answers the questions soon it will be easier to learn more about it cause if 4th is lower then 5th thats easy if not there is more to it whether its gears or crazy slip...

 

Neither have you.
Bottom line, what the OP is seeing is not correct.
Time for tcalgutie to do the fundamental tests outlined above to determine WHY

Until he comes back and states what the rear and speedo vs rpm checked out to anything else is pure SPECULATION

 

Have you read my posts?! All I have done is find where the problem could be and ask questions that havent been answered yet by him to find out what it is. I said check... READ!