why with o/d on does the car cut at 110mph ? its at 5500 rpms ... after 4 yrs it still doesnt make sense ...

1997 RS AUTO

ORACLE063
1/4 - 17.021
60' - 2.510
Weight 2730

I've never made it past 107 with OD on the entire time, If I'm going for top speed I usually leave it off until about 119, then turn it on, but then the car doesn't really gain any after that. I made it to about 122 once... I think I have too much stuff in my car.

not enough power/gearing to go higher

1998 dodge avenger 4 cyl AT
Mods are:
Not enough

I do you mean that it shifts into 4th at 110, instead of hitting 6464 first?

Mine shifts into 4th at 100 with OD on.

our cars can go 100mph in 3rd? wow. that's news to me.

1995 Eagle Talon ESi

n/a my car maxed out at 118. with all the bolt ons.

______________________________
Matt D.
'06 Evo IX SE
'98 RS-T 13.8 @ 106.1

As far as I know, 3rd reaches around 115. My speedo reads 120, but I know its off. I made a small program in VB that gets pretty close to determining the top speed of a gear. I fed it info and it gave me 115mph. This is with lockup on, and I have yet to do the final drive gear swap. With lockup off, the car acts very odd when it hits 6464 RPMs, and it won't shift, but it'll only do that if OD is off.

well i have a 97 rs dropped with just a cold-air, i am able 2 hit 116 in 3rd(od off)and have succesfully hit 137mph with od on.if u want 2 go faster you need good engine mods and tires.

the top speed with o/d off is 128 ... over drive is so flat i dont think it is allowed to go over 5800 rpms

1997 RS AUTO

ORACLE063
1/4 - 17.021
60' - 2.510
Weight 2730

Yeah, top speed with OD on is about 105-108,
OD-off allows you to go up to about 125-128.

The reason is because the engine is too underpowered at the lower RPM. If you downshift by turning OD off, you get just a little more HP in the higher RPM range.

Just look at any dyno graph and you'll see the car makes max HP at the higher RPM ranges. If you're not in the high RPM range, you're not making enough horsepower to overcome aerodynamic drag.

Another aspect to consider is the heat of the transmission. An automatic generates a lot of heat in the torque convertor. If you overheat the tranny, I think the A604 is capable of informing the ECU about it. The ECU might be able to cut back the power, although I've never actually seen this happen on my car.