I might add that the 2500 stall converter, a good shift kit, and modifying the kickdown circuit did wonders for the car....almost made the 400 trans tolerable :-)

Cheers
DD

 

Somebody with a 700 must have a smartphone app or one of those Gtech devices. I would really like to see actual #s. Or hell, take it to the dragstrip!

 

The numbers would probably be all over the board, just as they are with the 400 trans! So much depends on whether or not the engine is running correctly AND the WOT shift points.

Over the years some owners had a difficult time adjusting the 700/4L60 trans to upshift at a high enough rpm to get the most out of a 5.3 V12......which often is/was a problem with the 400s as installed by Jaguar. Unless you manually shift, of course.

I might add that if you plan on taking your V12 to 6500 rpm redline then a garden variety used/rebuilt 700 might not hold up well at all. I'm not an expert here but when I was contemplating the swap my reasearch (and conversations with performance-oriented trans guys) strongly suggested that various upgrades would be needed to ensure the trans stays together. I can't remember the details, sorry.

(BTW. Even if you keep the 400 you wouldn't want to install a plain-Jane rebuilt torque converter if you plan on high rpm use).

Anyhow, looking at potential acceleration improvements one has to look at the gear ratios; The 700 ratios are 3.06/1.63/1.00/.70 versus the 400s 2.48/1.48/1.00

One would expect that zero-to-anything would be improved due to the much lower first gear.....although the ratio drop into 2nd gear is so severe that you'd have to wind the engine up all over again, it would seem, which might blunt the results a bit.

In reality I think most XJSs are driven fairly gently so all of this WOT, shift speeds, 0-60 times, etc isn't especially important to most owners.

Just rambling....sorry :-)

Cheers
DD

 

I have put a ZF 4HP 22 with modified 24 innards ( ratios 2.48 1.48 1.00 0.73 ) with a higher stall speed lock up torque converter and a 4.54 diff in to my car. The motor has had some minor mods, with larger throttle bodies and exhaust. 0 to 60 times vary between 7.02 to 7.48 depending on the day. it all adds up to lots of smiles.

 

I see this is a couple of years old. I just recently got my 89, and have been noticing it's very sluggish on take off. Thing is with initial throttle punch the front end lifts like it's a blown 426 Hemi with 4:10 gearing, then the nose drops and it wanders it's way up to speed. I know mine has a TH400, was wondering about putting a 700r4 in it, but just wasn't sure if I should just keep it with a rebuilt or have mine rebuilt. It's currently at 113,230 miles on the trans? I am not sure what gearing I have in the rearend of mine either...

 

I feel like if I floor my 89 V12 convert, it chirps, but it doesnt sit there and spin. Does yours? My car runs fantastic but getting concerned something isnt right with my engine given what folks are saying above

 

I have a 1990 Coupe and never tried to burn rubber. LOL... I'll give it a spin tomorrow and see what happens.

 

apic of mine 78 Xjs 5.3L V12, also posted elsewhere, burnouts no problem, its ALL about the total gearing arraingments.

 

Do you h ave stock gearing? How did you do this? 1st gear and break?

 

sean, had that same trans in for 20yrs ,700R4 built with kit, light weight,hi stall convertor.

3.73 gears, hi bias Dana LSD, aluminum drivshaft(light).

of course the car only weighs 3360lbs (actual on a calibrated scale).

 

I use my tranny by putting it in D and going. Do any of you put it in 1st, then 2nd, then D? I always wondered if doing this in any tranny was actually good for it.

 

For those who have done this, or have any knowledge on it. I took the Jag on the highway this past weekend for the first time. Blew out my exhaust. Went to pass someone, both pipes broke at a clamp joint (Factory??) and I had to "hill billy" fix it.

However. I am noticing that when running 80 MPH, the engine is sounding very high pitched and running around 3500 RPM. I have the TH400 trans in it, and if I could would like to throw a 700r4 so I can gain another gear and a lock out torque converter. Mine is a 1989, has the 5.3 V-12, and I was wondering if it's a directr bolt up swap or if I will need to find a bell housing for it to bolt up. Also does the drive shaft need to be swapped out too? I am not looking to make a drag car out of the thing, I just want to gain another gear so I am not taking out a small mortgage to make trips around the country....

Any leads or help would be WONDERFUL!!

 

I'll to instal in to 4L80e:

4L80E 6-Pinion Planetary Sets (1991-96 2.97 1st/1.57 2nd Gear Ratios) - TCIŽ Auto

 

Yeah my 95 had the 4L80E..... It never got out of LIMP Mode even after putting 1800 into a total rebuild..... No thanks. I want to keep it as mechanical and NON computerized as possible.