I used the Quarterbreed kit from John's Cars. They must do good kits because my mechanic will gripe about anything, yet he had nothing but praise for the kit and the instructions.

The only thing we had an issue with was the dipstick. Either they sent one in the kit or referred to a part number that didn't fit. Easily solved by just going through a bunch of different cheap dipsticks from a parts house. We also had a bit of an issue with the detent cable but the shop worked that out.

Outside of that, everything went by the numbers. We had an extra tab of some kind on the heavy duty-spec case our transmission came in, so the shop had to grind that off so that it would fit under the car. From what they told me, once that tab was off, the transmission went right in, bolted up first go, no leaks, and the car cranked and went into gear like it came from the factory that way. Less than $1,000 for the kit and it seems like they have the process down.

Jess

 

Good info here, thanks.

I have an '89.

I wanted a 5 speed, but it would cost more than the car, and I have the ABS block to consider.

I was about to buy the John's T700 kit. I did one on a S1 XJ6 years ago.

The I see here that a T700 may not handle the high rev's without being race-built. I hadn't seen that stated before anywhere.

I have a 3.54 diff ready, as well a rear anti roll bar, which worked well on the S1 XJ.

THEN, look was pops up on my local buy and sell - a Simply Performance complete kit! I got it for about the cost of a standard T700 swap.

iscamerica's comment about the manual car being night and day over the auto, has spurred me on.

This project will have to wait until I get some other projects done first - I went a little crazy when I retired and bought a few cheap Jags to play with - but I can't wait to get started.

I actually sold this XJS to a friend and bought it back, knowing I'd have to re-gear it to be satisfied.

Thanks for all the knowledge!

Rob

 

i have always liked manual shifting!
BUT times have changed and so have i!
i would love to get an 8 speed AUTOMATIC DC trans , just to feel what a hi revvin V12 would be like!
1st gear launch would be like having a 4.56 rear gear, and so on up thru the gears at full throttle, and top gear would be like having a 2.20 final gear!
then again i'd only be wasting money that a 86 yr old guy has absolutly, no practical use for!
but you young guns go for it , but MOVE on up , i did my 700 swap in 1994, and so far no problems revvin over 60K/6500 rpms!
if i had a 7+ L V12 id use a GM/4L80e , from a Diesel truck/Van, junkyards are showing plenty available! for its able to handle the torque, and easy swap!
eon

 

doesn’t read like you checked the advance. Very often the advance gives up the ghost after 10-15 years. It’s hard to check since the distributor is on top and the timing marks are on the bottom.
on my race cars I put the timing on TDC and then transferred timing marks to a homemade marker I could read looking down with a timing light. Check your vacuum hoses too.

if your fuel is up to it the timing likes a little advance. Especially on the HE. But without a knock sensor it’s very easy to put more advance into the distributor than your fuel will stand.
If you go to E85 you can use the early 1971-1980 distributor and play with all 29-30 degrees of Instead of being stuck at what 17degrees? of advance
remember the earlier cars with a distributor timing is in the distributor not the ECM.

 

[QUOTE=icsamerica;2237415] Why a truck transmission was put in a performance GT is beyond rational and difficult to understand.

I do agree that the TH400 was used long after better choices were available. But to degrade it as a truck transmission certainly is not realistic. The TH400 was used by Cadillac and Rolls Royce because it is durable and very smooth. Jaguar chose it for the same reasons. Drag racers like it because it is strong. It is a very versatile gearbox and can be tuned for almost any application. I also see that much of the lack of response in TH400 vehicles is due to an inoperative kickdown switch. With the XJS, you have to put the pedal hard to the floor to activate the kickdown, and the kickdown portion of the throttle cable tends to seize. Usually an easy fix. My stick 83 HE will reach 60 in first gear, and will kickdown to first at lower speeds.

 

DL i dont think you get it,, the 4L80e is a turbo400 with an overdrive added, and electronics!
isca , being a little silly , the TH400 was built to have one BASIC transmission for heavy cars and light trucks, with big engine displacements= CU.INs.
not bad engineering for 1963!
ron

 

We have to accept that to some people originality beats modified. I’m not one of those people, I’m a racer. But I accept and respect those that are

 

MG my V12 ignition timing is at 1000rpm no vac. 24* initial , smooth curve till all in at 45* 3000rpm no vac!
i made my own weights and custom springs! in 1994!
i been playing with engine timing since 1950, when after WW2 fuel became much higher octane!
ron

 

[QUOTE=Dleit53;2239741]Fair point but we are talking about an XJ-S. the "S" stood for Sport. I'm not degrading anything by being historically accurate. Trucks...by the mid 70's that was the main application for the TH400. GM Trucks by the millions. Cadillac and Rolls Royce didn't use the TH400 and 4L80e in a 2+2 GT's becasue they didn't have one. GM used the TH350 and 700R4 in their 2+2 GT's with looser converters save for the short run of Big Blocks in the late 60;s to early 70's. I dont think RR had a 2+2 GT coupe. Porsche did a similar thing with the 928. They used a lazy but durable Mercedes transmission in their case. It's more responsive than the GM TH400 but not by much. I think the 928 got a 4 Speed auto in 1983 though, 10 years before the XJS. Both the 928 and XJS are less desirable as a result. The 928 was offered with a 5 speed and they have a much higher resale value and always did when compared tho their automatic counter parts.

 

jess , what year is your transmission 700,, becareful some early ones are weak and known to fail easily!
the best 700R4 come out of light trucks and vans at least starting around 1989/90, with TV cable, easiest to work with!
ron

 

The Corniche. Available in Coupe and convertible. Also the Camargue could be considered a GT.

 

Not sure. It did come from a truck because we got the heavy-duty case.

Jess

 

Corniche / Camargue are not a GT's in the traditional sense. Not every coupe is a GT. The term GT or Gran Turismo is mainly an Italian concept of a sporty but comfortable car for fast road use and capable of high levels of road holding at high speeds. One step down from a true sports car. Vehicles like the DB2, DB5, XJS, Ferrari GT 250 / 550, Lamborghini GT 350, Porsche 928, Corvette, Camaro, Mustang are all good examples of a GT. The Corniche is a Coupe and a nice one but it's more in line with cars like with the Cadillac Coupe De'Ville and Lincoln Continental Coupe where a smooth slush box would be appropriate.

Here's how you know for sure.....there are specific racing series for GT cars. Still kinda' popular and many GT cars can be converted to be competitive in sport car classes. This is True for the XJS, 928 DB's, Corvette's and the Mustang. The Corniche and De'Ville are not that.

But I think you stumbled on the problem with the XJS and many GT's from the era, I generally I love 1st/2nd year GT cars. They're more true to the designers original intent and lean to the sportier side. The early XJS' with it's lack of chrome and wood, better gears, manual sport seats, and rear sway bar was advertized with a 150MPH top speed. It was clearly positioned as GT. By the mid 80's things got a bit muddled, the market place changed and the XJS was trying to sit on both sides of the fence. Same thing happened with the 928. The manual transmission was seldom chosen in the later years, they got heavy and bizarre features like rear seat A/C became options. Then in the early 90's the BMW M5, Audi S6, Impalla SS came along and proved there was no reason a GT couldn't have 4 doors, that basically killed the segment.

 

I've oft said the same thing.

When introduced the XJS was competitive in "Performance GT" market.

Time marched on and the XJS didn't. When it was no longer a true player in the performance/GT world it was the marketed ...in the USA at least....more along the lines of a 'personal luxury car'

Cheers
DD

 

There aren’t a lot of us left capable of doing that. I still own my distributor machine. I silver soldered my weights on and At one time probably had 200 different springs and still was buying more because the ones I had that tension was right were too short or long. I’ll need to hunt for the system I put together to trigger it. But it’s in the shop someplace.
I’m surprised you run that much total advance. That’s more than Group 44 ran.
I suppose you can get away with that much if the air density isn’t that high. Or humidity is very high. ( or very high octane fuel)
Remind me, are you using the HE head or the earlier Flathead? What compression pistons?

I just stumbled onto a British XJS. Early, higher compression 9.0-1 instead of 7.8-1 and right hand drive. According to the manual it’s 861 pounds lighter than mine. Makes 33 more horsepower. And is Right hand drive.
The bad news is the bottom is pretty rotten. Doesn’t look bad in pictures but the floors are out and very likely the front crossmember too. (I have a good one among all my spares).

 

MG , im using a 1979 pre block and heads , euro pistons at 9.0-1 ratio, gold coated tops, Total seal GAPLESS rings!
heads are modded by yours truly, Lightweight 3mm over SS valves by Grp44, 2MM over SS valves Grp44, custom,.050 thou. cut off the flat head surface, valves now protrude down into the bore(exposing more curtain flow area) coated thermal Ceramic coating, also comp ratio now around 9.2-1, seats blended and flowed into valve itself! light porting thruout port!
EXhaust ports and manifolds ported and Coated thruout!
much time spent on heat control evacuation after combustion(did not want any chance of overheating), That my EXPERIENCE showed at Daytona 24 races most V12 Jaguars ended up losing the potential wins!

 

I used to increase the intake ports but found no gain as I increased exhaust ports.
I found the best cams were the billet by Kent but now I need to stretch my budget to just buy a pair of Re ground cams. I used to have a friend ( Barry Cams) who reground cams. He might still have some profiles. I found Offy profiles worked pretty good.
Before I started to use NASCAR Chevy Rods I used a home made jig to cut the top and bottom weights off the stock rods. If I remember the numbers correctly that means I can reduce the weight of the crank by something like 12 pounds. From its stock 78 pounds. Won’t make any extra power but should increase its ability to rev quicker.

 

While I completely agree with your sentiment, production numbers would tell you most buyers preferred the superior fuel mileage and wood dash over the more pure GT car.
Some years barely 1,000 cars were sold but once the HE came out sales went over 10,000 units for the first time. The more of a poseur our car became it seemed like the better it sold.
I remind you very darn few of the V12’s came with the optional manual transmission

 

Styling and trim upgrades, and the HE engine....and resulting favorable press reports.....did indeed save the car. Getting people into the showroom is always half the battle.

Cheers
DD

 

The sluggish early sales figure were a result of the Gas Crisis that started in 1974 and persisted to 1979. The 70's are called the malaise era for a reason. By about 1982 consumers started buying gas guzzlers again and XJS sales increased. In 1982 Porsche 928 Sales were also about 2.5 times what they were in 1978. This period was also a competitive time for GT's. There were so many on the Market. The 928, the BMW 633Csi,, Corvette Camaro, Mustang, Datsun 280ZX and many more. As a result Automatics, mirrors and creature comforts persisted to attract more woman buyers. These items were cheap and performance was expensive. It was the age of Dolly Parton's "9-5" and "Workign Girl" and If you look at advertising literature from the period this is evident. Averts tended to not include men or woman at all and some featured woman exclusively. Like this XJS add below and this 928 Advert explicitly directed at woman. In hindsight, this was clearly a mistake. BMW didnt do this any by the early 90's, Both Jaguar and Porsche were near bankruptcy and BMW was the only game in town... an advantage that persists until today. Back then BMW offered Manual transmissions and exhausts that made engine sounds. .


Just a sign of the times, and nothing wrong with refreshing a used car you love for the times you live in. Gear changes, manual swaps, engine swaps...All good to me.


https://blog.consumerguide.com/model...oupe-ads-1979/