high rpm

[journey50]

i have a 91 explorer xlt 4 door 5 speed with the 355 front gears not sure of back ones on highway at 75mph im at 3000 rpms my brother has a 91 xlt also with 5 speed and he is like at 1800 why does my explorer rev so high on the highway, i have michelin ltx tires 235/75/r15 is it the rear axle size or gear ratio?

 

[410Fortune]

75 MPH at 3000 rpm with stock tires does not = 3.55

all 4x4 have the same gear ratio front and rear.

Who told you 3.55?

Sounds more like 4.10 or 3.73, but something is whack.

With the 5 speed at 75 you should be around 2250 if I remember right.

Also consider somebodys speedo might be off. there are alot of factors that will change your RPM at speeds, gear ratio is the main one when comparing similar trucks. Tire air pressure, engine age, etc all can play a factor.

 

[kdogg212001]

i have undersized tires on my 94 xlt, i also have 4 doors and 4x4! with my set up i sometimes can pull off 65mph at 21-2200rpms when speedometer shows 75 its about 24-2600rpms! only time i see 3k + is when i am going 85-100mph << not to often! lol just though i would see if i could a couple times!

 

[journey50]

yea im not sure if the speedo is off or not and i havnt had anybody drive along side me to see if its correct i dont sound like its a 3000 rpms but the tach says it is, its a tach from a 93 sport would that make any kind of difference at all, its all stock so no one changed any gears in it at all.

 

[kdogg212001]

if your explorer is stock then you will definitly be able to notice if your actually pushing 3k rpms! your engine should sound like your alomst done! lol or how else to put it! hmm your engine wont be able to push much more past 3k rpms stock~ even with my little mods i can get about 85mph before i hit 3k rpms! definity somethings not right! are the tires the right size???

 

[journey50]

my x has 235 75 r 15 tires on them all michelin ltx m/s all have only about 2000 miles on them i mean it gets good gas mileage and eveything, it has an axle code of 45 and it has plenty of power when i hit the gas at 75 just didnt know why tach would read at 3000 i put a tach from a 93 explorer sport in and it fit so i assume it would work right, ill try to put my old tach back , could it be the front end is engaging in 4wd when i drive it? :exp:

 

[Creager]

i dunno that might be about right

Axle code 45 - 3.55 non-limited slip (Explorer/Mountaineer)

whats yr brothers axle code?

less then 3000 rpms at 75 sounds about right to be honest

i had 3.27s, 29" tires and would hit about 2750 at 75mph in OD

i always thought that was kind of high, but that was how it was.

 

[journey50]

his 91 also has 45 axle code and my parts 93 eddie bauer has a code 41 when im at 75 its right at 3000 rpms but it dont sound like its gonna blow up or anything like that i was just wondering if that was the way it was supposed to be or not.

 

[kdogg212001]

75 at 3000rpms doesn't sound right to me! cause like i said i have undersized tires and i am doing 75mph at about 2500rpms! something isn't right i think!

 

[journey50]

no clue either.. x runs like a champ plenty of power no smoking or crappy running she is well taken care of and not abused been like that since i bought her drove ehr fron ny to ga and back at 80 m + the whole time and still got about 20 mpg on the highway just thought maybe itw as from adding the 93 sport tach to the 91 instrument cluster

 

[kdogg212001]

hmm not really sure either! i am getting my bbk tb soon cant wait to see the difference! oh yeah i like to take care of my x also! except i do put a bit of abuse on it! i like to take the corners a little rough! parking lots are a fun one! lol

any whom hmmmm still no guess as to what the issue could be! hmmmmmmmmm

it would be awsome if a 1st generation explorer could get 25-30mpg! that would be awsome! lol