Hey guys,

I'm seriously thinking about a t-5 or t-56 swap. I had thought about it in the past but it did not seem cost effective, but over the past two years, my 700r4 has cost me more time-off-the-road (and money) than any other part on the car. Plus, I hate automatics. hate. Especially in a car like the xjs. It's a crime.

I have a 1989 xjs with a 350 small block crate motor. It makes somewhere between 300-350 HP.

I have a few questions before I decide to go the manual route:

1. Will my current transmission mount match up with a t5 or t56.

2. The t56 is a double overdrive tranny, correct? Will this be "too much" for my 2.88 rear end ratio? Would the t5 be a better choice? Switching out rear gears sounds like a real pain.

3. Will my driveshaft match up? Or will I have to get it modified (again)

4. This seems to be the biggest issue with this swap: The master cylinder. The dreaded master cylinder. I have read all mikds of mess about this issue. My xjs (being an abs model) apparently naver came in a manual model. This would appear to leave me with a few options

- Convert to non abs and search both US and EURO junkyards for a master cylinder setup.

- pay ~$800 for a custom built ABS master cyl (with clutch pedal and cyl).

Either of those options would, hands-down, be the most expensive part of this swap. Both put me over budget. If there is no other option, I'll have to stay with the slush box.
Is there any way around this? could the clutch pedal out of another car be fitted into the xjs. Could the xjs firewall be "modified" to fit the new clutch pedal assemby?

Please, Let me know what you guys think.
Thanks,

Cody

 

Afraid I have no technical info to share with you regarding the manual swap. I've been considering the 700r4 swap for a while though. What sort of problems have you had?

 

the T-5 that came in the 3400 f bodies wont even hadle the torque of a naturally aspirated 3800, let alone a SBC (which is the reason you couldnt get a 3800 with a 5 speed after 1998. i had the same idea, and got some good advice from the firebird forum. the T56 is the one you want. plus double overdrive is nice. expensive transmissions though. theyre starting to become a collectors item.

deathkitten did a manual swap for his 350. he used an S10 slave cylinder and a T5 trans, but im not sure what he got it out of. the ones that came out of the 6cyl f-bodies are built to a budget.

https://www.jaguarforums.com/forum/x...ld-ride-38914/

 

Death kitten has a pretty good build. I wonder though, if the pedal assembly yould work considering his is a non abs model.

The 700r4 is a decent transmission. Its a pain to set up the TV cable. The 1st and second gear ratios are terrible. Mine is a pre '86 unit so, its inherently weaker than newer models. Mine has just been problematic. Its been rebuilt twice. The pump went out on it once. It was off the road all of April due to parts in the valve body sticking (the car would sometimes not shift out of first.) Now that I have it back home, I realize that the TC will not lockup in OD.

If you get a post 86 unit with low miles and rebuild it... I'm sure you'd be just fine.

Its so popular becuast they're 1. Cheap 2. Everywhere. 3. Well... its just about your only option.
IMO, the 700r4 sucks the life out of a Chevy power jag. It takes all the fun out! (And a lot of HP due to high parasitic losses)

 

and its a lot heavier. but what stall TC are you running? IMO 3000+ stalls are an absolute must for a high ratio final drive. my Grand Prix has a 2.93 final drive ratio, and a 3k stall converter, and i can still break the tires lose at 40mph in 1st.

but the whole point of the 700r4 in a Jag, is to take advantage of the OD and upgrade to an X300 ring and pinion (3.54?) wihtout losing highway economy.

 

I currently have a 2200 stall converter installed. Its my daily driver so, it was built with fuel economy in mind.

The 700r4 OD and the 2.88 are a great combilation on the highway. @75 I cruise under 2krpm. I've gotten well over 20mpg on the highway

 

my supercharged 3800 gets 38-40mpg on the highway with 3k stall 2.93's and lockup. i get about 17 in town.

 

hah! sounds like my jag! i get under 15 in town but, a best (so far) of 26 on the highway. huge difference.

okay. this may all slowly be coming together.


It looks like the t56 is .5" longer than the r4. This means that I may still be able to use my stock driveshaft. I also read somewhere that the transmission mount and yoke are the same. score. Ever better, my SBC is a one piece rear main seal, just like the lt1. translation: the lt1 trans, flywheel, and clutch, should bolt right up.

The biggest pain is still going to be the clutch master cyl.

I've found a couple of folks who seem to have done the swap recently. I'm going to see if I can track them down and ask some questions.

 

get ahold of death kitten about that S10 cylinder. he should be able to help.

and youll definately be able to use the stock driveshaft. there should be a little bit of wiggle room in the motor mounts and SBC trans support so you can adjust for length.

 

S10 Slave cylinder* my bad

 

When I did my 700R4 install I remember buying the driveshaft from John's Cars. I think it is a different length than stock. You should check on that before assuming it will work.

If you do not care about ABS brakes why not convert to standard brakes?

 

i was talking to Andrew at Jaguar specialties, and he said those SBC conversion mounts are designed for quite a bit of fore and aft adjustment, since the SBC is so much shorter. you should be fine.

 

The only thing keeping me from converting to non and is cost. That and the fact that, the more I research, it looks like an abs model will cost as much to convert to manual as a non ABS model.

 

would somebody explain to me what the problem is with putting a manual in an ABS car?

 

Not exactly sure but it is probably the pedal box that is the issue.

 

cant you just bolt in an aftermarket clutch pedal assembly? they sell them at my local speed shop.

 

10-4

abs and non abs have two different pedal boxes and brake master cylinders.

this makes it difficult for abs folks as the only abs manual cars were a very (very) select few 4.0L 90's cars. these are nearly impossible to find.

The only options are to convert to non abs (which manual boxes can be found for over in the UK). or mod your abs box.

If anything, I'll be going with the second option



I'd definitely like more info on this universal pedal box though. the only ones I've seen online go for around $400. I'd be better off ordering the modification kit from the vintage jag site.

 

hmmm... this is interesting,

Has anyone taken a look at one of these?


Summit Racing 14-0011 - Summit Racing® Master Cylinder and Pedal Pro Packs - Overview - SummitRacing.com

 

nm. thats what i would do personally. theres tons of good stuff from summit