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1987-1991 Parley with regards to your 1987 to 1991 Bonneville, Olds 88 or Buick Le Sabre Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 08-26-2005, 01:26 PM   #1
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Default Late shift at WOT

I have a problem with my transmission. At WOT in drive the trans doesn't want to shift. Well it probably will but very late. When I floored it today in 1:st gear the tach went to 6000 rpm before I let go of the trottle... then it shifted to 2:nd. I havenīt yet tested 2:nd to 3:rd and so on.
Except for that it works perfect.
I donīt know if the transmission have been replaced previously.
What controls WOT shifts on these transmissions? Only the governor?
Car is 1988 SSE with vin C engine.
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Old 08-26-2005, 01:45 PM   #2
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No governor. I think the 88'* were controlled with vacuum. Could the vacuum modulator be faulty?
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Old 08-26-2005, 01:50 PM   #3
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6,000RPM eh? That'* high. Anyways, since the transmission shifts after you let off the throttle, that eliminates any transmission issues. The only thing that controls upshifts at higher than part throttle is the TV Cable. My guess, is it is completely disconnected. If it is still mounted properly, it is either mis-calibrated or the TV cable system has completely broken.

The TV Cable is mounted on the stud which the TB butterfly is mounted on. Do you know how to give throttle to the engine while under the hood? It'* under that metal braket where all the throttle components are located and mounted.
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Old 08-26-2005, 01:59 PM   #4
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I think it could be tranny related. Lotsa things could alter shift behavior.
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Old 08-26-2005, 02:27 PM   #5
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I checked the TV cable and it seems to be OK. What is the proper way to adjust it? Is it supposed to bottom out right at WOT?

The vaacum modulator mostly controls the shift firmness, right?
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Old 08-26-2005, 03:04 PM   #6
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I don't know about the cause, but I have the same problem on mine. I just "lift to shift" when necessary.
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Old 08-26-2005, 06:45 PM   #7
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Yea i have the same problem. Just don't rev it that high. And i don't think you hit 6k rpm for real, your tach must be off. Don't the 88'* have limiters? Anyways i wouldn't worry about it i think it'* just a tranny quirk that we all have.
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Old 08-26-2005, 06:59 PM   #8
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There supposidly is a fuel cutoff somewhere around there, but I don't think anyone has found it, nor I have i found any documentation of a real number [i have found documentation of the fuel cutoff existing, but no rpm to go along with that]. I think it'* possible the car reached 6k. I've been up around that territory, although the car makes no power up there, you could still push it up that high.

If your TV Cable is all in tact, mounting wise, then you must adjust it. This is per the Haynes manual.

Quote:
1. Engine MUST NOT be running during this adjustment.
2. Depress the readjustment tab and push slider through the fitting [away from the throttle lever] as far as it can go.
3. Release the re-adjustment tab.
4. Manually turn the throttle lever to the "wide open throttle" position until the adjust tab makes an audible click, then release the throttle lever. The cable is now adjusted.
Note: Don't use excessive force at the throttle lever to adjust the TV Cable. If great effort is required to adjust the cable, disconnect the table at the transaxle end and check for free operation. If it is still difficult, bent TV link in the transaxle or a problem with the throttle lever.
The 'readjustment tab' is located on the rear of that throttle bracket. The gas pedal'* throttle and the cruise control'* throttle are mounted to the rear of that too. The tab it speaks of is pointing up and is somewhat bulky. The tab isn't the most obvious, but you should see it. If anything follow the line from the butterfly stud down, and you'll then find it.
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Old 08-27-2005, 08:23 AM   #9
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Quote:
1. Engine MUST NOT be running during this adjustment.
2. Depress the readjustment tab and push slider through the fitting [away from the throttle lever] as far as it can go.
3. Release the re-adjustment tab.
4. Manually turn the throttle lever to the "wide open throttle" position until the adjust tab makes an audible click, then release the throttle lever. The cable is now adjusted.
Note: Don't use excessive force at the throttle lever to adjust the TV Cable. If great effort is required to adjust the cable, disconnect the table at the transaxle end and check for free operation. If it is still difficult, bent TV link in the transaxle or a problem with the throttle lever.
The 'readjustment tab' is located on the rear of that throttle bracket. The gas pedal'* throttle and the cruise control'* throttle are mounted to the rear of that too. The tab it speaks of is pointing up and is somewhat bulky. The tab isn't the most obvious, but you should see it. If anything follow the line from the butterfly stud down, and you'll then find it.[/quote]




Thanks! Iīll try that!

I didn't know this was a common problem on the bonneville, but sice it is maybe someone have heard of it before and knows the cause.
I looked in a Haynes transmission repair manual and it shows that the THM440-T4 and 4T60 transaxles has a gorvernor mounted below the speed sensor housing.
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Old 08-27-2005, 10:58 AM   #10
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they do have a governor, but I believe all it does is prevent the car from upshifting or down shifting at the wrong time. I've tested it. If you are going 55, and put the car into "1" on the gear selector, it won't downshift to first, but it will stay in the next highest gear. That'* what the governor does.
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