I just bought a 86 XJ6 with the GM 350 and 700R transmission. I am more familiar with the GM 400. In all the gears, it has a rather soft shift. The 2nd gear will flare if I press the throttle hard or give it a lot of gas. My mechanic says there is no adjustment on the 700. Any help or suggestions appreciated! The fluid level is correct and is a bright red.
Richard
Whose kit is on the 700R to install, I wasnât aware of Jaguar using them?
Change mechanics, then Google GM700R4. I like BowTie Overdrives
Great transmission, but it needs to be adjusted to run with the rear end. The reason I ask is that Johnâs Kit is pretty specific about setup.
If someone just transplanted one without doing a proper setup you may experience some expensive problems.
These transmissions are favorites of hotrodders, as they will take a lot of horsepower. They wotk nice in Jags too.
if it IS a 700R4 then it should have a TV cable(throttle valve), it should be agjustable , tighten cable increases shift pressure and raises shift point MPH!
i have one and it us great been 25yrs still runnin fine! overdrive makes hi way cruisin fast and quiet!
ron
âadjusted to run with the rear endâ ? Why would the trans care as to the rear end?
Aye, I recall that John has opined that the 700 r has OD and if the car has a 2.88 ratio, it might be a too high final ratio for the torque of the IL 6.
But, others have done it and are pleased, even if .70 x 2.88 !!
The SBCâs can handle the .70 OD x 2.88 just fine.
My LT1 does with the 4L60E. A close relative to the 700r.
Carl
Greetings All,
âAdjusted to run with the rear endâ should read, adjusted to the rear end ratio.
Go to BowTie Overdrives and read their article.
Read, re-read, then read again all the tech on Bow-Tie Overdrives. My 700R4 is paired to a 3:54 Power-Lok. Could have went with the 3:90. 
The Bow tie site sends me elsewhere. subscription needed, I chose not!!
So, if you think the Rear cares?/ so be it !
Carl
because the load (torque) determines when it shifts. a higher torque engine would cause it to shift early while a weaker one would shift late. lower gears (higher number) will also cause early shifts while highway gears would hold the gear longer. the governor determines when this happens. readily available for cheap or grind off some weight until it is right. a shift kit and different stall converter also effect shift points but I would start with the governor.
Thanks. All quite correct. However, this is in the transmission it self.
But, I see the point, at last!!!
Lower gear ratio in the rear differential effects engine rpm at any given MPH. That effects the transmission shift point. Early shift! 3.31 to 1 as an example
And, a high ratio causes a later shift as to MPH. 2.88âs as in many XJâs. Mine included.
I did not mess with the 4l60E, a close cousin to the 700r. The LT1 torque pulls those tall gears, event with the .70 OD with alacrity.
Now, some say the 4.2 and 2.88 canât pull a 700 because of the high OD. others say, no, it does well.
OTH, the torquey 4.2 in my 94 Jeep pulls OD well. No where near as spy as the LT1, but quite decentâŚ
Different cars are driven differentlyâŚ
No snow around here, but the Jeep in 4WD and on true M&S tires could go where the Jag dared notâŚ
Carl
given two identical vehicles with the only difference being the governor, they will both accelerate from a dead stop the same and turn the same rpm in forth at high speed. the difference is the heavier governor will force an early shift. it would be in forth at 50 mph lugging the engine at 1600 rpm while the lighter would still be in third turning 2100. while keeping rpmâs down usually improves mileage, going too far lugs the engine and uses more fuel than an engine effortlessly moving the vehicle at an rpm in its âpower bandâ. there is no one size fits all but raising or lowering shift points can make an underpowered car more lively or tame a high revving gas guzzler.
Sounds like a stock 700r4 with a stock torque converter. A shift kit and higher stall torque converter will make a big difference, but wouldnât be quite natural for an xj6. Adjusting the tv cable as mentioned is crucial for proper shifts. Also, make sure you have the lock-up kit installed properly. A competent trans shop should be able to adjust and confirmed all that
Richard,
The mechanic is wrong on two counts - either or both of these faults can cause early transmission failure:
1⌠The transmission shifts are adjustable within certain limits, and the TV (throttle valve) cable must be adjusted correctly to achieve proper shifting.
2. No one has mentioned the lock-up torque converter. It must be wired to achieve lock-up in at least fourth (OD), or once again, early transmission failure could occur.
I believe that Bowtie Overdrives has an online tutorial for each of these items.
The later 350âs with tuned port ,or port injection, used the 4L60E (electronic version of the 700R4) which was controlled by the engine PCM (computer). Adjustments for wheel diameter, rear end ratios, and shift points could be made in the PCM via the ADL port (pre-OBDII) or via the OBDII port on the later engines.
How much work is involved in changing to this trans? I have a xj12 dana rear in my 72 xj6 not sure what year ratio is for dana xj12 1983. Any help much appreciated or is it worth the gain for overdrive???cheers
The differential in your car just might have a tag as to the ratio. It might even be limited slip. A good thingâŚ
Compare the revolutions of the drive shaft to the wheel. Touch as 2.88 is not that much different than 3.54 or so!!
Many have used the OD with 2.88 behind the 4.2 and find it does well.
It sure does behind my LT1!!!
Carl
Itâs almost certainly a 2.88 ratio.
Besides the overdrive 4th gear the 700 also has a low ratio 1st gear. Arguably, considering the already tall 2.88 final drive, you may benefit more from the lower first gear than you would from the overdrive 4th gear.
Cheers
DD
Is overdrive worth it? The short answer is âDependsâ. With a â6â and âairplaneâ gears, I doubt it. Then it becomes how many other things are you going to change. Tire height, stock engine? modified 6, V8, engine power band (torque curve), style of driving.
How much work is it? âDependsâ. Depends on the kit you use and your skill set. You need to subscribe to âCalifornia bolt on, some modification required.â TV cable is no picnic, at least in my mind. I setting mine right now on a rebuild. Pan off, makes it much easier to see what is going on with the initial settings.
A 2.88 becomes a 2.016 final drive with a .7 overdrive. As DD said you have the advantage of a lower first , 3.06, but I donât know the power curve to the Jag 6. My guess is youâll have a dog on your hands in forth. A 3.54 with a .7 OD is a 2.48 final. I made an Excel spread sheet with multiple variables, rpm, transmission gear ratios, rear axle ratios, and tire size. With that you can see your speed at a given gear, at a given RPM.
Have you driven the old and the new setup for seat of the pants comparison?
I will check out California bolt on! I have never been in any comparisons. Thanks clyde. Lots of info.
Not necessarily a subscription, more of a mantra.
I had a 700r4 in my 420 sedan. Wasnât a fan of it. Now converting to a Jaguar 4 synchro overdrive transmission.