Wrong gearing maybe?

[R.E.D]

Hello all , my buddy and I picked up a 2001 sfa ch613 sleeper truck , 427 , 10 speed eaton and 4.17s on Hendrickson air ride.truck looks and rides great..on the lower gears and the two gears after going into high range it pulls like a bat out of hell but the remaining gears it falls on its face.no flash codes on the dash.would like to know if the transmission was switched from the original one that came with it , maybe with one that had different spaced gear ratios.....last six of vin are 139047.thanks in advance...

 

Red

Edited 23 hours ago by R.E.D

[Joey Mack]

Good looking truck. What is sfa? 

[R.E.D]

Set forward axle...and yes sir, it's well kept for its age.. brought it back from Orlando to Houston bout a month ago . Since then we've been busy installing a brand new wet kit, raising and fixing the fifth wheel pivot and a bunch of other little things

Edited 22 hours ago by R.E.D

[Joey Mack]

Ok..  gotcha.. I know it as axle forward.  I'm stumped on the power issue. Is boost dropping off? Or is it just weak from the start in 8th-10th? 

[R.E.D]

2 minutes ago, Joey Mack said:

Ok..  gotcha.. I know it as axle forward.  I'm stumped on the power issue. Is boost dropping off? Or is it just weak from the start in 8th-10th? 

It's not equipped with a boost gauge , but pyro doesn't seem to go above 900 on hard pull...and yea those last three gears seems like the rpm range dont fall on the sweet spot , and just won't pull ... eventually it will come up to speed but it just seems like the rpm range and transmission gearing are off. We've tried shifting all over the RPM range and same result every time.

[fjh]

I would get a boost gauge! That said! Another question! At what Rpm does it pull best at in the other gears? A 427 has a flatter  wider torque than other power options  and that my have been the mind set on the trans option! My self regardless of ledged power out put I would always chose more gears if I was ordering a truck ! I know this doesn't answer your question But its  just my two bits worth! The lower gearing may also be key also ! Best you ban do watch what you have if your not trailing smoke and the pyro is happy drive it!

[R.E.D]

1 hour ago, fjh said:

I would get a boost gauge! That said! Another question! At what Rpm does it pull best at in the other gears? A 427 has a flatter  wider torque than other power options  and that my have been the mind set on the trans option! My self regardless of ledged power out put I would always chose more gears if I was ordering a truck ! I know this doesn't answer your question But its  just my two bits worth! The lower gearing may also be key also ! Best you ban do watch what you have if your not trailing smoke and the pyro is happy drive it!

I agree with that ..we had another option to buy a truck with a 460 but chose this one for the 427 flatter wider torque curve..we've been trying to get a 13 speed sourced out ,since we hope this would fix the wide gap in between the top gears ,but kinda wanted to figure out if it was a gearing issue or power issue...buddy and I have both owned trucks with  t2090 trans  and 4.17 gears ..I had a 350 hp pln and he had a 400 hp etech and both would pull harder than this truck.also would like to mention that this lag is present both loaded and empty.boost gauge is coming , also will dig out from my horde a pressure gauge with a long enough hose to check fuel pressure while engine is under load.

thanks all

red