One, my XJ-S has ~63K miles on the clock, and I can't remember if or when the transmission fluid was changed. There is great little local oil change place (not a chain) that I take my Range Rover and daughter's LR2 to, and the last time I was there they were running a special on a trans fluid and filter change so I asked the owner about the Turbo 400 in the XJ-S. He said bring it by and he'd check if it needed it, and he said it didn't -- fluid was cherry red, smelled exactly like new fluid, etc. However this morning I had a car show on in the background, and they made a comment about how you should change the fluid no later than 60K miles, and that if you didn't damage would begin. Should I change the fluid anyway?

Two, is there any reason not put in B & M modulator? Seems like the easiest and cheapest performance enhancement possible on the XJ-S. Does anyone have experience doing this?

Thanks!

 

B & M adjustable modulator a great idea, you can adjust the change points to your liking.
If the fluid is bright clear red you do not need to change it. The fluid change is easy enough to do, but the Jaguar installation of the GM 400 has an anti-shunt device on the rear that must be undone before the pan can be lowered.

 

Mac Allan,

I agree with Greg re. the colour.

A basic fluid and filter change is fairly easy. However, for me the bigger issue is that if you just drop the sump, you'll only get out less than 1/3 of the total fluid. So, having completely flushed my 4.0 24 months ago, I've then introduced a different regime of just extracting the fluid from the sump using a vacuum extractor pipe down the dipstick every year and replacing that much fluid. That way. I'll keep fairly clean fluid in the system all the time. I'll then do a full flush and filter change again after another 48k miles from the last full flush.

Paul

 

Hello to everyone I have simple questions regarding the Differential Fluid
I'm Owning XK 2010 5 litre engine not super charge very happy with the car.

1) What is the difference between Castrol SAF-XO 75W90 And Castrol BOT 720 ?

2) Can I use Castrol BOT-720 instead of SAF-XO 75W90
Today one delar told me that there the same he bring to me BOT-720
Maybe For XKR they made better performance Fluid ?


3) I Read some post regarding the FRICTION MODIFIER
Castrol SAF-XO 75W90 and Castrol BOT-720 he has or must be add extra this FRICTION MODIFIER ?

Thank you
Ivelin Popov

 

Ivelin

I think you'll get more appropriate replies and suggestions if you post this in the modern XK forum section

Good luck

Paul

 

I would definitely go with the B&M kit. Not only are the shift points adjustable, but the response is much improved. Make sure you update to the latest vacuum modulator

 

Yes, the manual transmission is cool, but not cheap pleasure for me.
So i diceded to rebuild my transmission th400 and install transgo shift kit 1&2 or pro (didn't know what the differnce between this 2 kits?).
As i understood with transgo shift kit i can turn 1 gear and 2 gear at any speed and rpm, and if at speed i will turn from 1 gear to D - i will drive on automatic?

I choosing between:
Hughes Performance GM25 Torque Converter 12″ 2500 Stall https://www.summitracing.com/dom/parts/hup-gm25
Hughes Performance GM25HD Torque Converter 12″ 2500 Stall https://www.summitracing.com/parts/hup-gm25hd/overview/
TCI Breakaway Torque Converter 11" 2500 Stall https://www.summitracing.com/dom/parts/tci-240900
TCI Breakaway Torque Converter 11" 2500 Stall anti-balooning plate https://www.summitracing.com/dom/parts/tci-240901
Freak Show Performance Converter 9.5" 2500 Stall

0) Which company to choose ? Smaller diameter is better ?
1) All this torque converters can fit to original jaguar flywheel or not ?
2) ARP 230-7303 - ARP Torque Converter Bolts --- this bolts can fit perfectly ? What the size of original bolts ?
https://www.summitracing.com/dom/sea...verter%20Bolts
3) what the pros and cons of new TQ with 2500 stall over original jaguar torque converter ? somebody have experience with it ? engine 5.3l - th400 - diff 2.88 plus new TQ with 2500 stall or better save my money on it and install old original TQ ?

 

I used a TCI converter on my 1988 XJS (2.88 differential), 2500 stall speed, and was happy with the results. Better/faster acceleration from a stop.

I didn't purchase it from a vendor but, rather, called TCI and had one built-to-order. It was about $500 with upgrades (details forgotten at the moment, but I do remember discussing balancing and ability to safely withstand 6500 RPM). The fellow I spoke with was familiar with the requirements of the Jaguar/400 combination ....but this was probably 15 years ago

The Jaguar converter uses 6 bolts. Most converters only use 3 bolts. I recall having mine built from a 6-bolt Jaguar core but the typical 3 bolt converter fits the Jaguar flex plate.....it's just that 3 bolt holes will be left unused. I don't think this is particularly consequential. I think virtually all 400s converter have the same bolt pattern but in the back of my mind I recall a couple odd exceptions. (I'm just on my first cup of coffee!)

I can't remember which shift kit I used. Pretty sure it was B&M. No matter what brand you choose I suggest going with the mildest upgrade. A too-firm shift can become annoying.

Cheers
DD

 

I went with the medium kit. One of the things I love about the kit with the upgraded modulator is the firmness of the shifts. At low to moderate throttle, the shifts are just noticible.

But stick your foot in it, and not only does the trans stay in the selected gear longer, but it KICKS when it shifts.

As an aside, I have just finished rebuilding the 722.3 trans in my Mercedes S600. I found that these models were made to start in 2nd, to avoid having to use a heavy foot on the brake at a light. The kit I installed in that allowed me to re-valve it so it started in 1st. And to feel a big MB long wheelbase sedan kick and chip tires when winding up that V12....

 

I had a '71 Mercedes 250 with the stupid 2nd gear start. I hated it. Anyway, looks like I'm buying an adjustable modulator for my Jaguar unless there's already one on there. I need to look. I'll be putting lighter weights in the governor as well. The intake and exhaust mods have released some more top end that the transmission is not letting me easily use.