regear and shift point question

Ok I’ve got a 98 with a auto tranny I’m running 33’s and 4:56 gears, according to my GPS my speedo is off by 10 at 60 (speedo reads 70). When I’m going up a hill if I don’t mash the gas the jeep will climb getting slower and slower and the RPM’s will go below 1200 before it down shifts at which time it will jump up to about 3000 and it will stay there for what I feel is a long time before it up shifts again. This seems to be creating a problem when pulling my pop-up camper, by the time I get to the top of a long hill I’m doing 30 at close to 3000rpm’s and the jeep gets hot and if the hill is a couple miles long I overheat. I’ve replaced the whole coolant system not the fan clutch yet but that seems to be fine. My question is, is this a shift point issue if so how can I adjust shift points, do I need a chip? Or is this not a shift point issue at all.

Sounds like your camper is over taxing your tranny causing it to overheat which in turn is causing your radiator temp to climb as well. Since the radiator cools the transmission fluid as well. I would first change the fluid in the tranny (or at least make sure its full) and add an external cooler. As for the shift points, the extra weight of the camper is off setting the 4.56 gears you have. So your jeep is acting like it has 3.53s again. Not much can be done here except giving it extra gas in the at the bottom of the hill to get the RPMs up and to get it to gear down before you lose your momentum going up the hill.

there are a couple things that trigger the torque converter to unlock... one of them is the brake pedal. every one and a while if my comanche is running hot it'll do the same thing you are describing. i've found that sometimes if i let off the gas real quick and push it back down, it'll downshift. if that doesn't work, i just tap the brake very lightly (not enough to make the brakes actually come on) and that will cause the torque torque converter to unlock and sometimes trigger a downshift.

j33pownr said:

Sounds like your camper is over taxing your tranny causing it to overheat which in turn is causing your radiator temp to climb as well. Since the radiator cools the transmission fluid as well. I would first change the fluid in the tranny (or at least make sure its full) and add an external cooler. As for the shift points, the extra weight of the camper is off setting the 4.56 gears you have. So your jeep is acting like it has 3.53s again. Not much can be done here except giving it extra gas in the at the bottom of the hill to get the RPMs up and to get it to gear down before you lose your momentum going up the hill.

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I should have mentioned that I installed a tranny cooler sorry. I do question though the idea that a 4:56 and 33's put's me back to stock, if that were the case wouldn't my speedo be a lot closer. The reason I say that is because if I try to get speed at the bottom of the hill it just seems to stay at the higher RPM longer, I'm actually starting off at 3000rpm's. I have better success letting it stay at a low RPM it's still going 30mph but doesn't get hot, however I think I'm doing more engine damage cause I'm really lugging along at like 1200 rpm's not sure which is worse real hi or real low.

Did you put in the correct speedo gear to recalibrate?

cal said:

Did you put in the correct speedo gear to recalibrate?

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And that will effect the shift points!

cal said:

Did you put in the correct speedo gear to recalibrate?

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No still the stock gear but I echo RCP Phx said that shouldn't make a difference in my shift points does it? I was just using the fact that the tire and gear set up isn't quite back to stock.

gabe4 said:

No still the stock gear but I echo RCP Phx said that shouldn't make a difference in my shift points does it? I was just using the fact that the tire and gear set up isn't quite back to stock.

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It may affect the shift points? If you unplug the speedo on that rig you'll get a check engine light.

RCP Phx said:

And that will effect the shift points!

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Nope. The trans computer has no idea how fast you are going. It only knows the input rpm (98 and up) and the output rpm from the tranny sensors.

Yes, speedometer gear is only for the speedometer and odometer. Not shift points. Well, with XJ's anyway, not sure about today's crazy technologically advanced chit

This seems contradictor to the problem but I’ll ask it anyway, would a taller tire help(no I’m not looking for a excuse to go bigger). It seems if I try to get momentum at the bottom of the hill I just stay in third the whole way up the hill and by the time I’m to the top I’m hot. If I got a taller tire would it allow me to get more speed? I say this only because I’ve had stock looking XJ’s pass me on those same hills while pulling similar looking trailers like I was standing still.

I've adjusted the cable on the throttle body, it seems to have made the shifts less violent, but the RPM's are still high

gabe4 said:

I've adjusted the cable on the throttle body, it seems to have made the shifts less violent, but the RPM's are still high

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Makes sense, The throttle cable controls the hydraulic pressure in the tranny, hence affecting shift firmness. The trans computer controls the shift points.