So, I've been reading tons of stuff on transmission conversions for series 2 XJ6s... I'm struggling to decide on what to do, but I'm sure the old BW65 has to go. Hate it with a passion. Originally, I was sure I wanted a 5 speed for the fun and performance, but the T5 conversion is EXPENSIVE. I've recently looked into the Dellow kit for a Supra W58 5 speed, price and availability of transmissions looks promising... found one locally for $100. The 700R4 offers better ratios and I'm sure much better shifting, and would be more in keeping the the intent of the car.

Looking for testimonials from folks that have used these conversions. I'm sure many have the 700r4 behind a chevy v8, but I'm most interested in how it works with the Jag 6.

I am planning a full rebuild with 9 to 1 pistons, late big valve injection head, and I have the triple Su setup, so power will be much improved, just want a suitable transmission to enjoy it.

Pic of my car:

 

Nice Jag




No personal experience but I've never heard a single complaint about the TH700 swap. Always good reviews. And, yes, easier and less expensive than a manual trans swap. In the grand scheme of things it's probably the better, more sensible, more practical way to go.

But.....

Higher compression, big valve heads, triple US carbs....that's all just begging for a manual trans. Since it's you money (not mine) and your labor (not mine), I say "go for the gusto" and do the 5 speed

Cheers
DD

 

1. 700r or the like. Adds OD, very desirable. Johns cars sells a conversion kit. But, opines that OD is too tall a gear fore the 4.2. However, that may apply to the cars with the 2.8 ratio. Earlier cars had lower ratios, and might not be included in that opinion. Nevertheless, I've read of folks using it on early and late and being pleased. A given is that our Jaguars are heavy. But, cars with much less HP and torque have pulled OD just, albeit with a much lower rear ratio.


2. A fellow has posted his experience with a Mustang sourced T5 and some related gear behind his 4.2. The BW 65 housing and an adapter joined the two. Mechanical clutch linkage bsed on Mustang stuff.


Well, let's see, I've read that a healthy 4.2 pulls 265 HP? My LT1 claims a mere 260 HP. It pulls a .70 OD and a 2.88 rear with aplomb. I admit to a bit of tongue in cheek!!!


But, my conclusion is that the healthy 4.2 can handle the OD just fine.


Carl

 

700R4 ,less cost, almost perfect ratios, 1st gear to get moving quickly, OD for hiway cruisin!

what else would one need, does your 4.2 have the 3.54 rear gear ratio?

that would be great!

 

Contrary to the beliefs of some (mainly V8 aficionado's methinks!) the Jag 4.2 is no slouch. On the contrary, this engine is very strong with great pulling power and the T700 tranny is the catalyst that lets it all loose, no comparison with the old BW 3sp which stifles the engine's potential IMO. It is a perfect match. Go for it.

 

Thanks for the replies... I believe my car as a '76 series 2 has the 3.54 rear axle ratio... hence the dire need for an OD. Freeway driving at 70 Mph equals about 3200 RPM which is no place for a long stroke torque monster engine to be cruising.

Agree that the 700r4 looks promising and cost effective. I prefer manuals in my cars, but don't know if I really want to shift gears in the Jag... seems like the wrong experience.

 

Being a Toyota Supra fan for 35 years, just a warning that Toyota used our W58 for many, many years in multiple models and there were differences between years and models that you might want to research as well as issues and parts. There's a lot of information in the forum at celicasupra.com. But it is a fairly robust transmission and people put them in all sorts of vehicles. Good luck with your project.

 

Manual surely wouldn't be the wrong experience in an XJC in my view!

But I'm pretty sure it's going to be a 3:31. I have a 350/700r4 in my xjc coupe, and a 4.2/700r4 in my '86. If you're going automatic, 700r4 is worth the money and the only way to have an auto xj6. It's what BL should've done in the first place and may have saved the car as it was. It makes the car drive (even with the 2:88 diff) more like a modern car. With the BW trans it's just a damn slug, with the 700 it still ain't no bmw, but it's much more driveable in town and has enough acceleration that most econoboxes aren't bitching for you to get out of the way.
The JC kit is def the only way to go but with one caveat. I found that the TV cable was being treated as a kickdown cable (as on the th350/400) when it is in fact an entirely different and important animal.
ref.Bowtie Overdrives | TV Made EZ

I took the time to engineer a proper adapter plate for the jag throttle body to affect the correct geometry for the tv cable and my trans worked properly after that. I did need to change the governor springs to tailor the shift points, and a simple vacuum switch to unlock the TC I would recommend. The lugging that JC talks about, (imho) is caused simply by the TV cable not traveling in the proper path. They advise using a high stall torque converter to counteract this, but I would use a stock low stall converter and the proper TV geometry.

That said, the kit is fantastic to install, the support is awesome and you'll have a car that accelerates and cruises like it should have in the first place!

 

I would love to follow your 4.2 rebuild with 3/su's etc... I have a euro 4.2 core with 3 su's on the floor waiting to replace the 350, and a manual pedal box for the xjc. Just have a couple other projects in the way at the moment.