CASANOVA86

thats wut im assuming cuz everybody stays next to me more or less but they end up passing me, so unless everyone is doing 90+ mph on the highway

ISFFUN

iTrader: (4)

Maybe the speed sensor was damaged or is worn out?

RyanV

iTrader: (9)

Maybe it's not an SC300 W58 and the final drive gear ratio is different?

You sure it's not an R154 trans?

My R154 with the 4.08s sucked on the highway. I can't imagine an R15t4 with the 4.22 rear gear on the highway.

vangb2

iTrader: (2)

The W58 and R154 final gear is not too much in different. They should not be too far apart.

R154 Ratios:
First Gear: 3.250:1
Second Gear: 1.955:1
Third Gear: 1.310:1
Fourth Gear: 1.00:1
Fifth Gear: 0.753:1

W58 Ratios:
First Gear: 3.285:1
Second Gear: 1.894:1
Third Gear: 1.275:1
Fourth Gear: 1.00:1
Fifth Gear: 0.783:1
Reverse: -3.768:1

If your overall wheels is bigger than stock, you should be going fast than what your speedometer indicate.

v8soarer91

come on guy's and girls there is a little thing called a speedo "gear drive"

they come in different colours acording to the ratio needed.

we have an electronic speed sensor "Vehicle Speed Sensor" mention in a previous post which is calabrated to the r154, a341, a340 boxes.

the only 2 diffs in the soarer!!!!!!!!!

v8 3.9
tt 4.11

i can put a tt box in my v8 and the guage will still see correct revs but the speed would be going faster than it should.

to get around the difference geardrives and the given pulses it sends to the cluster is to use a Speed Sensor Calibrator.

some cars us the sensor on the gearbox, gauge cluster, ecu, or a combo of any of these.

@ 4000 in 5th you should be doing around 160kph - 100mph

seems like that you need to change the drive gear in the gearbox.

Gspec

My 5-spd swapped 92 SC3 runs around 3,000rpms @ 75mph on the factory auto diff (18" wheels)....the w58 was out of a 93 SC3. It's def not as bad as I thought it was gonna be.

I swapped out the computer and gauge cluster for the 5-spd units as well though.

Pipe

I have the same exact problem with my car mine is an A/T , Is there a speed limiter in the car?? I thought i was going faster so i broke out my TomTom stuck it to the glass and both speeds matched WTF?!? 4K at 60 my gas millage sucks!!!

Shadowen

iTrader: (6)

Rev the engine to the rev limit. See if it goes past what the limit should be. If it goes higher than the limit, you know that your rpm gauge is just off.

Pipe

If i rev it it goes all the way over

good2go

iTrader: (6)

Just an little FYI,

revving your engine to redline without any load is generally frowned upon by your engine.

Pipe

I def know that one ,but all my cluster needles (except fuel) are out so most times im flying blind .

CASANOVA86

Mine does the samething