How many speed is this transmission?

[shintan17]

Hi, I have a 96 GC Limited with 5.2 V8 engine. I just realized that my automatic transmission shifts 4 times and I thought this A518 transmission is 4 speed which supposes to do the shifting only 3 times. Does anyone know what may cause this problem? Please, reply me!

[ChadEbert]

OK, so it starts out in first gear, so first to second is one shift, then second to third is the second shift, then third to fourth is your third shift. So, it should shift three times from a standstill to the last gear. Maybe you're feeling the torque converter kick in or you have difficulty counting.

[chris5.2]

hi chad , what do you mean ," converter kick in "?

[msrjeep]

overdrive engages a clutch at high speeds to lock the torque converter to the transmission speeds, giving better fuel economy. it also changes the ratio past 1:1 which is why it is called "overdrive"

[hardisk_c]

I think I'm following Chad. I have a 94 Grand Cherokee w/ the standard 4-speed auto, and at around 30 mph there's a kind of 'half-shift' before it goes from 2nd to 3rd. Someone tell me if that's actually something wrong w/ the transmission?

[YtseJam454]

Let me explain this correctly for you.
The torque converter clutch lock up mode does not give you an overdrive ratio. The Converter clutch can lock up in 3rd or 4th gear to eliminate the approximate 10% slip between the Impeller and Turbine speed. This causes a thermal efficiency loss and a fuel economy loss. 3rd gear is typically direct drive. A 1:1 ratio where 2 planetary members in the transmission are held. That means the input planetary member and output planetary member are turning at the same speed. However, there is still a difference in speed from the Impeller and turbine. The Impeller is driving at the engines crankshaft speed and the Turbine is turning the transmission input shaft at about 90% of Impeller speed. Since no torque multiplication is needed at this point, the torque converter clutch (or TCC) applies, locking the turbine to the Impeller causing it to eliminate that 10% slip between the crankshaft and the transmission input shaft. What you feel at this point is the engine RPM drop slightly. When the transmission shifts into overdrive let's say .85:1 ratio, once again the TCC can lock for the same purposes and again you will feel a slight drop in engine RPM.

Now, here is a test you can do to verify it's operation and feel the TCC engage/disengage. Drive the vehicle on the highway and once you are in high gear and feel the TCC apply, maintain your cruising speed with your right foot. Gently apply the brake with your left foot, just enough to turn the brake lights on, you should feel the TCC disengage. Repeat this a few times to get the feel of it. Many people seem to think the TCC applies an overdrive ratio which it does not. Hope this clarified a few things as far as TCC operation. You may need to read this post twice. Good luck

[msrjeep]

i wasn't saying the TCC was an overdrive. i was saying it engages when the car shifts into overdrive. it (as in overdrive) shifts into a taller gear greater than the final 1:1 gear.

[ChadEbert]

Good gawd, YtseJam, that was wonderfully technical. My 98 GC 5.2 has 110,000 trouble free miles on it, have only replaced the brakes. When I'm driving it and it settles down at highway speed in 4th, the rpm's will drop a little bit (maybe by about 300-400 rpm's) once I'm cruising. This has got to be what msrjeep referred to. I dunno. Sorry it took me a while to get back to you, I was in San Francisco on business.

[dksob81]

I am having a problem with my tranny, actually i don't know if it is a prob or not. from a stopped position, start driving, shift into 2nd around 12-14 mph, than shift again around 18mpg, I don't think it should shift again that soon but I'm no tranny specialist. is this normal or is there a problem.

[drummerb86]

Im not sure if that a problem or not. What i do know is if your doing alot of city driving i found it easier on my tranny if i turn the overdrive off. Just something i found that works for me anyway. It tends to shift smother. Only good upto like 45mph though.

[ByronP]

Just to answer the original question, the A518(46RH) is 4 speed automatic.
ByronP