88' Xjs Th400 mph per gear?
#1
88' Xjs Th400 mph per gear?
car is running really good now, I'm just speedometerless but I use my gps... I'm wondering what the normal rpm shift point is and if my rpms might be off? Car shifts at 4500 when wot. If I use the shifter and put it in first it gets to 4500 or so and bucks like it hit redline... same in 2nd gear. Hit 4500 and bucked right at 85mph. What is the max speed per gear in the xjs th400? And if I'm not able to hit redline is that seem like a centrifugal advance or vacuum advance issue? Cause I think both might be in so so condition on mine. Thanks
#2
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Common issue/complaint....early shifts.
If *manually* shifted at redline the shifts will be at about 65 and 110 mph.
In '89 a change was made to increase shift points at WOT...but I can't remember the details
On my '88 I had a shift kit and adjustable modulator and the WOT shifts were at about 6000 rpm. In reality not much is gained, in terms of power and acceleration, by going right up to 6500 rpm. Prior to the mods it shifted at about 5000 RPM as I recall
The trans on my present '88 V12 (sedan, not XJS) shifts at about 5500 at WOT
Your bucking could be an ignition fault
Cheers
DD
If *manually* shifted at redline the shifts will be at about 65 and 110 mph.
In '89 a change was made to increase shift points at WOT...but I can't remember the details
On my '88 I had a shift kit and adjustable modulator and the WOT shifts were at about 6000 rpm. In reality not much is gained, in terms of power and acceleration, by going right up to 6500 rpm. Prior to the mods it shifted at about 5000 RPM as I recall
The trans on my present '88 V12 (sedan, not XJS) shifts at about 5500 at WOT
Your bucking could be an ignition fault
Cheers
DD
#3
#4
Common issue/complaint....early shifts.
If *manually* shifted at redline the shifts will be at about 65 and 110 mph.
In '89 a change was made to increase shift points at WOT...but I can't remember the details
On my '88 I had a shift kit and adjustable modulator and the WOT shifts were at about 6000 rpm. In reality not much is gained, in terms of power and acceleration, by going right up to 6500 rpm. Prior to the mods it shifted at about 5000 RPM as I recall
The trans on my present '88 V12 (sedan, not XJS) shifts at about 5500 at WOT
Your bucking could be an ignition fault
Cheers
DD
If *manually* shifted at redline the shifts will be at about 65 and 110 mph.
In '89 a change was made to increase shift points at WOT...but I can't remember the details
On my '88 I had a shift kit and adjustable modulator and the WOT shifts were at about 6000 rpm. In reality not much is gained, in terms of power and acceleration, by going right up to 6500 rpm. Prior to the mods it shifted at about 5000 RPM as I recall
The trans on my present '88 V12 (sedan, not XJS) shifts at about 5500 at WOT
Your bucking could be an ignition fault
Cheers
DD
Thank you
#5
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Location: Pacific Northwest USA
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Cheers
DD
#6
On A TH400 the shift point is controlled by the governor weights and springs. I have a Daimler limo with the TH400 and it shifted at 2700 rpm! Just as the engine started making power, it shifted.
I took the governor from an older Suburban and that was just about right, I think shifts are ~5300 rpm now.
I took the governor from an older Suburban and that was just about right, I think shifts are ~5300 rpm now.
#7
On A TH400 the shift point is controlled by the governor weights and springs. I have a Daimler limo with the TH400 and it shifted at 2700 rpm! Just as the engine started making power, it shifted.
I took the governor from an older Suburban and that was just about right, I think shifts are ~5300 rpm now.
I took the governor from an older Suburban and that was just about right, I think shifts are ~5300 rpm now.
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#11
On jag-lovers it describes that if the governor won't even allow you to hold past it's rpm if you toss it in 1st etc? Will it shift up to 2nd if it's in 1st? Or will it just hit the governor and buck like hitting the rev limit?
#12
#14
Could simply be weak springs. Or it's been replaced in the course of the cars life with an incorrect part. All the TH400 governors from any GM product will drop right in. It's behind the square cover on the right side of the transmission.
There are quite a few combinations of weights and springs that have been made over the years. I pulled junkyard ones until I had one that I liked the shift points. I think it was from an early 80's Suburban, but it might have been a Cadillac.
There are quite a few combinations of weights and springs that have been made over the years. I pulled junkyard ones until I had one that I liked the shift points. I think it was from an early 80's Suburban, but it might have been a Cadillac.
#15
2nd gear RPM before shifting is indicated to be around 5200-5300, but that does not fit with the above info.
I guess I will have to check both instruments for deviation. Í have done it for the speedo, but only at more sensible speeds, where it (except from fluctuations) is pretty accurate. I actually hope it's my rev counter, that is off
The rear end of the car does by the way get very loose, when it shifts to 3rd at WOT on wet roads. Scary stuff, but it's great to know the beast has some power...
#16
Could simply be weak springs. Or it's been replaced in the course of the cars life with an incorrect part. All the TH400 governors from any GM product will drop right in. It's behind the square cover on the right side of the transmission.
There are quite a few combinations of weights and springs that have been made over the years. I pulled junkyard ones until I had one that I liked the shift points. I think it was from an early 80's Suburban, but it might have been a Cadillac.
There are quite a few combinations of weights and springs that have been made over the years. I pulled junkyard ones until I had one that I liked the shift points. I think it was from an early 80's Suburban, but it might have been a Cadillac.
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