Help! Crusing @ 60mph 5th gear 4000 revs

[nando]

the only think I can think of is if you have an eta coding plug in an I tach

[slammin.e28]

Swap in a good cluster and see what it reads. Easiest diag IMO.

........

[supkev]

[supkev]

^ I have lined up and done that already, I have also used gps to measure my speed though its not accurate it reads 56-60mph its not that far off

[zxert]

He said he drove next to someone who verified the speed.

[LJ851]

Perhaps you have a close ratio gearbox. How do you engage 1st gear?

[pandaboo911]

Your speedo is wrong you're actually doing 85 :P

[slammin.e28]

I'm telling you - there is no way a 4.10 will do 4000rpm at 60mph. Not unless you're running rubber band tires on 13" wheels.

This.

Swap in a good cluster and see what it reads. Easiest diag IMO.



You say you have a Euro cluster? Maybe it's in metric RPMs? ;)



JK.

[nando]

I'm telling you - there is no way a 4.10 will do 4000rpm at 60mph. Not unless you're running rubber band tires on 13" wheels.

I get 2800rpm at 60mph with 205/55-15 tires (23.9" diameter) and a 4.10 with the .81 G260 5th gear. with my 235s it just a hair lower.

and a 3.73 with stock diameter tires is 3400 at 80, not 3000. people exaggerate a lot.. 4000rpm with stock diameter tires and a 4.10 is over 85mph, not 80mph as many claim.

[joonsup]

a 4.10 is about 3000rpm at 60mph, not 3500-3700. 80mph is about 3750.

on my 3.73 lsd i'm hitting 3000rpm at around 80mph in my 5 speed stock transmission

[zxert]

I don't think that fluid will have anything to do with it, though changing it is always good. Think about it, a differential is either engaged or it isn't. Fluid or lack of fluid doesn't play a part in RPMs. I honestly think there isn't a problem. It sounds like you have a 4.10 diff with a 3.73 cover. What year and model E30 do you have.



Here are the gear ratios for different models (SEE ATTACHMENT)

Heres a calculator that will tell you RPM. Just input the data for your model and BAM! You're pregnant. I mean, your RPM.
http://www.f-body.org/gears/

I put in the numbers for a 325i 5 speed w/ a 4.10 and got 60mph @ 3100rpm just as nando says.

Post what transmission you have and we can help you.

Also post which differential you had before and RPM at speed with that diff.

[nando]

your tach is probably not reading correctly

[supkev]

Damn what could be the possibilities for my high rev on freeway's :/

[nando]

a 4.10 is about 3000rpm at 60mph, not 3500-3700. 80mph is about 3750.

[supkev]

Now if I had a 4 banger 318 I would understand but in my I6 hmm I get like 22mpg combined 16-17 city but I know other people with 3.73 are getting better than what I get.