Is my 700R4 getting to OD? Cant tell. - Hot Rod Forum : Hotrodders Bulletin Board
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Old 04-02-2013, 04:09 PM
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Is my 700R4 getting to OD? Cant tell.

This is a rebuilt transmission (stage 2 build rated up to 500hp by a well known builder) It runs through the gears fine. I can feel 1 to 2 shift, 2 to 3 shift and 3 to 4 shift, but it just seems like my RPMs are still really high while in fourth. The most I have pushed it to was about 60 mph and it felt like it was well over 3000 rpm. I cant actually verify this as I do not currently have a tach in the car, but definitelly seemed to high for an OD.

I'm running it behind a 350 sbc with 2200 stall, 4.11 rear gears and a 28" rear tire. I'm not really schooled in AOD transmissions. What, when and how does the trans no how to go into OD if it's already in 4th? Or is 4th OD? I have a bowtieoverdrives brake pressure switch lockup relay and I have confirmed with a tester it's doing what it is supposed to be doing when the brake is applied.

Is there a simple way to confirm it is getting into OD without a tach?

Thanks!

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Old 04-02-2013, 04:20 PM
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Not sure how the 700 work like others, but is it possible your not in 4th, but still in 3rd, and your torque convertor is just locking up. I think some of the 700 were wired to lock up in 3rd and 4th. You need to put a tack on it, and then you'd know.
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Old 04-02-2013, 04:27 PM
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Well I can easily feel 3 shifts. Will going to lockup in 3rd gear feel just like another shift? If it does then that may very well be the case.

BTW, the trans only has about 10 miles on it. Not sure if it will "loosen up" over time allowing an easier lockup. Like I said I'm still new to the trans.

I did test my pressures with a guage and dropped the pan to confirm throttle valve depression, so I'm pretty positive the TV is where it should be.
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Old 04-02-2013, 05:13 PM
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When it shifts into 4th, you should feel and hear a real difference in rpm's . lock up will give you not alot of feel and sound of rpm drop. Hold it in 3rd for a while till you can get an estimate of your rpm if you can. When you shift into drive, you should get the sense that you rpms dropped by about a 1/3. If your doing 60 and you think your running 3000 rpm's in 4th, Your not in 4th. Don't care if you have 4.11 gears. You need to call the builder and ask some question. Maybe one of the 700 guys will jump in. I think there is a way of preasure testilng if you got a 4th gear problem. Also you need to put a preasure gauge on that tranny and that will tell you alot. Also look on the net about preasure testing and that will give you some advise.
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Old 04-02-2013, 05:24 PM
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I did pressure test it at idle, but I didn't while driving. I could be wrong about it being over 3000 rpm at 60 mph, but it had to have been close. I was just expecting to be able to cruise nicely at 60-70 with this trans. Based on my short driving tests it appeared 60-70 would be winding up the trans to much to be a comfortable "cruise" speed.
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Old 04-02-2013, 05:47 PM
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You got to do it the right way or you won't be driving it long. It will burn up those clutches in a hurry. You need a preasure gauge. You need to search the net about how to do it. Don't take my word, read about it. Get that tack and find out for sure. Then you can see the rpm changes when you drive it.
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Old 04-02-2013, 06:45 PM
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you may have a stuck T.V valve.. I'm having the same problem right now.. does it seem like it's shifting late on the other shifts? my tv valve is stuck near the wot position.. so it slams into gear from park HARD.. and it grabs 2nd gear with some enthusiasm even at part throttle, and it refuses to shift into 4th.

some 700r4's (like mine) will lock up in 2nd, 3rd, and 4th.
i use a brake pedal switch and a toggle switch on the dash, that's it.

just for a frame of reference for you.
I run over 3000 rpm in 3rd gear @ 70mph, and it drops to around 2500 in 4th, and then down to 2250 rpm when the TCC is on.
with 3.55 gears and 27" tall street tires. (255/60-15)
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Old 04-02-2013, 11:39 PM
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Quote:
Originally Posted by kc8oye View Post
just for a frame of reference for you.
I run over 3000 rpm in 3rd gear @ 70mph, and it drops to around 2500 in 4th, and then down to 2250 rpm when the TCC is on.
with 3.55 gears and 27" tall street tires. (255/60-15)
Good to know, Thanks
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Old 04-03-2013, 06:09 AM
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You didn't say if it was build to shift into OD hydraulicy or electricly. Without knowing that nobody can give you a good guess.
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Old 04-03-2013, 10:51 AM
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When you TCC locks, you will be able to add throttle and the rpms will not come up at all. This is because the trans input shafts is 100% locked to the same speed the TC case/crankshaft is turning. When not locked, there is an rpm difference between the input shaft and the TC/crankshaft. You can push and release the throttle a small amount and you will be able to hear the engine rpms come uo and down a bit.
A locked TC will feel like a manual trans equipped car.

Properly working TCC will lock in 4th for sure, and if you hold the throttle steady with your right foot, and then press and hold the brake pedal just enough to turn on the brake lights, the TCC will unlock. The TCC will also unlock when you release the throttle 100%.

Easy thing to do is, place selector in 1st, then accelerate until engine is r3vved up, then slip the selector into 2nd, then accelerate until engine revs up, then slip trans into 3rd, the slip into 4th. You will feel 3 distinct shifts, and TCC application will make the car feel like a manual trans car.

Some vehicles have the TCC lock in 2nd, 3rd or 4th. This is called the lockup strategy. This is why yoiu need to determine by feel, if the TCC is locking up. When the TCC is locked, throttle response is decrease markedly over an unlocked TCC

peace
Hog
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Old 04-03-2013, 04:51 PM
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Quote:
Originally Posted by Hogg View Post
When you TCC locks, you will be able to add throttle and the rpms will not come up at all. This is because the trans input shafts is 100% locked to the same speed the TC case/crankshaft is turning. When not locked, there is an rpm difference between the input shaft and the TC/crankshaft. You can push and release the throttle a small amount and you will be able to hear the engine rpms come uo and down a bit.
A locked TC will feel like a manual trans equipped car.

Properly working TCC will lock in 4th for sure, and if you hold the throttle steady with your right foot, and then press and hold the brake pedal just enough to turn on the brake lights, the TCC will unlock. The TCC will also unlock when you release the throttle 100%.

Easy thing to do is, place selector in 1st, then accelerate until engine is r3vved up, then slip the selector into 2nd, then accelerate until engine revs up, then slip trans into 3rd, the slip into 4th. You will feel 3 distinct shifts, and TCC application will make the car feel like a manual trans car.

Some vehicles have the TCC lock in 2nd, 3rd or 4th. This is called the lockup strategy. This is why yoiu need to determine by feel, if the TCC is locking up. When the TCC is locked, throttle response is decrease markedly over an unlocked TCC

peace
Hog
Hey, I appreciate your detailed description. I will take her for a drive this weekend if it's clear and play around with the gas pedal while running in 4th to see if I can determin lockup or not. What do you mean exactly by saying the TCC will make it feel like a manual trans car?

Thanks again!
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Old 04-22-2013, 06:26 PM
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Quote:
Originally Posted by Hogg View Post
When you TCC locks, you will be able to add throttle and the rpms will not come up at all. This is because the trans input shafts is 100% locked to the same speed the TC case/crankshaft is turning. When not locked, there is an rpm difference between the input shaft and the TC/crankshaft. You can push and release the throttle a small amount and you will be able to hear the engine rpms come uo and down a bit.
A locked TC will feel like a manual trans equipped car.
I have a tach on order now and will install it this weekend.

I do have a question about the above post though. This weekend I took the truck out for a short drive and noticed while driving above say 45 that if I stepped on the gas lightly that it would rev up but not transfer to the wheels. Then if I slowly stepped into the throttle at the same speed it would rev a little before actually transferring power to the wheels. Does this mean I am in lockup or that I am not in lockup?

Once I install the tack I should be able to see lockup engage without any question them?

I might add that my truck's interior is hollow right now and the exhaust is quite loud which really makes it hard for me to determine RPM. 1800 may feel/sound like 3000.
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Old 04-24-2013, 07:38 AM
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My r4 drops 300 RPM when in OD, noticeable but may be hard to tell. 3.90:1, 30" tires. 300 RPM doesn't sound like much but makes 70-80 MPH much nicer.
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Old 04-25-2013, 06:07 PM
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Thanks Fang16

How about the rpm revs before power transfer question I asked a few days ago? Is there nobody here that knows if this is a sign of being in OD or not?
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Old 04-25-2013, 09:19 PM
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Originally Posted by RatPin View Post
Thanks Fang16

How about the rpm revs before power transfer question I asked a few days ago? Is there nobody here that knows if this is a sign of being in OD or not?
Not sure what u mean by: rpm revs before power transfer . That could be a combination of TC, pipes, not being used to the car/engine. After you get ur tach in and you see the RPMs we can tell more. On the side, you'd be surprised at what a difference tire size can make.
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