Which Gear ratio do I have?

[Robert]

You are definately not going in to overdrive. With a 4.10 axle, your stock tires should be 255 70R16 (about 30"). You also have a 4R55E transmission which is mechanically the same as my 5R55E, at least as far as internal gear ratios go. If you are at 3000 RPM at 60 MPH, you definately are not in your top gear. It may be something as simple as a solenoid or servo, or it may mean time for a rebuild. I just got my '97 rebuilt last week. It ran fine and I probably could have gotten many more months, however it did have some problems that I was concerned about. My problems started with a harsh downshift when coming to a stop. With my SuperChip in, the downshift was so harsh it activated my ABS. I had to pull my SuperChip to lessen it a bit. Next thing I noticed was my engine would rev up slightly just before each upshift. It only did this about every tenth shift or so. It wasn't consistent. The last thing I noticed was that it had a very harsh clank when I put it into R or D. Hoping that it was my valve body gaskets, I replaced them along with updating the valve body seperator plate. I also did a complete flush with Amsoil transmission fluid. None of this did anything towards helping my transmission problems (didn't make it any worse either though). I took it in to the shop that rebuilt my Wife's Sable transmission since they did good on it. They pulled the transmission and disected it. I was amazed at how varnished all of my clutch plates looked. Also all of the rubber seals were very hard and a couple of servos were sticking. I authorized them to go ahead and to a complete rebuild at a cost of $1960. They also recalibrated my valve body to firm up the shifts slightly. I felt that I have kept up with the maintenance pretty well (definately better than my Ford Service Booklet recommended) yet I still needed a rebuild at 104K miles.

Just because it is shifting OK now doesn't mean there isn't something seriously wrong. It may be something minor, however it may turn in to something major if let go. When we first got my Wife's Sable, it slipped badly only under full throttle shifts. It acted this way for a couple of years before the transmission lost OD. At one point my Wife asked me to drive her car since something didn't feel right. As soon as I got it out on the highway it was apparent that it never shifted in to OD. We scheduled an appointment to have the transmission rebuilt the following week. On the way up to the appointment, the car also lost 3rd gear. All of the soft parts inside the transmission were destroyed. I wouldn't let it go to long before getting it looked at which will take a qualified transmission repair person.

 

[Alec]

Just my 2 cents:

If it is going into OD but not locking the TC, the RPMs will be about 300-400 higher than they should be in OD. It is possible you're going into OD but your TC isn't locking.

 

[Bashman]

Alec: This may seem like a dumb question, but is there any way to test or check the TC without yanking it out?

 

[mbryda]

This one I know!

Go on the highway @ a steady speed. Note your RPM's. Let off the gas and touch it again. Your RPMS should go up ~300-500 and then settle back down. That's the TC unlocking (when you first give it gas agiain) and then it locking (when the RPM's settle)...

As far as the codes - not sure. When my OD light was blinking, the trans guy (and me) thought it was just electrical, as it was shifting fine up to that point (and wouldn't shift out of 1st at WOT). Turned out to be a slip in 2-5 gears. Rebuild time. Turns out my TC was shot, and then inside of the trans looked like it had 150k on it (per him), new OD sun & Planet gear (over $900 in parts alone)... Andthis was at 59k with a fluid change @ 36k. Must have got the Monday morning hangover trans!

 

[Texasplorer]

Man I just want to say MUCHO THANKS for all the info and support on this matter.

I just wanted to give you an update:

I called my local Ford Dealership and talked to an Shop Foreman and he says I need to see if its switching into all 4 gears which he stated the 4th gear will be OD as long as I have it on.

So I did an test today and YES I did feel 4 gears switch, and here is the delima.

When it switched to the last gear (4th gear OD "ON") @ 60 mph I was reving @ 2500 RPMS. I can be only at 45mph to even get 2000 Rpms.

Also what I did was check the idel out at an dead stop with tranny in PARK and it revs to 1000 rpms. Now,,, from my experience the rpms @ idel seems to be high and I think it should be around 800rpms,, so if my idel'ing RPMs are at 1K could this be a matter that possibality that is maybe why my rpms @ 60 mph @ 2500 rpms??

I dunno but I am sure since I tell you guys I did feel all 4 gears switch that the tranny is fine,,, so what can it really be???


Thanks all!

Oh forgot to mention I never had an "check engine light " come on.

 

[mbryda]

If you're at 2500 @ 60, you're fine with 4.10's. That sounds about right.

When I was out today on the highway I paid a little extra attention to the RPM/speed and it was at about 85-90 that I started pulling away from 3000 RPM's, so you, at 2500 @ 60 seems about right on the money. As long as you're getting 4 distinct shifts you're fine.

Don't worry about wear on the engine. I have an 86 Mustang 2.3 with a 4 speed stick that is ~ 3000 RPM's @ 75, and has been driven like that since I got it with 58k on it. Now it has 175k on the original engine!

For the idle, check the sticker under the hood (emissions) - IIRC it states what the idle shold be. If it's too high/low, check your IAC and clean as necessary.

 

[haloXpert]

how can I tell if my gear ratio has been previously altered? Just got this '98 V8 AT. Door code say 3.73 but whoever owned it previously put 31"s and an aftermarket exhaust. The thing REALLY moves from a stand still and I think they might have up the lowered the gears... but how do tell for sure?

 

[Bashman]

The only way to know if it was changed is to pull the pumpkin apart and count the teeth. I am also running 3:73 with 31's and didn't lose any take off speed, in fact I can still spin the tires on dry pavement.

 

[haloXpert]

thanks!