Ideally, it would be a pretty middle-of-the-road setup for gears 1-4 (or 1-5) with 5th (or 6th) gear being a gas-saver. I will never drag race the car. My performance background is in autocross. I care most (in a 5-speed transmission) about gears 2-3-4 being usable, especially as passing gears, because I frequently travel two-lane roads with short passing sections.

My current driving style is more grand touring than performance but when I do get the chance to drive in a more "spirited" fashion on curvy roads, I certainly take it. While we're doing the trans swap in this car, we'll also be upgrading the suspension to handle those duties. The factory setup is much too soft for my liking.

The problem is, I have read most of those threads, and I get turned around very easily because there are a lot of strong opinions and everyone seems to either love their setup to death, or issue strong warnings against certain setups. I would prefer to leave the 2.88 rear in place, mostly as a cost savings issue. What I'm interested to know is whether I can get a vendor (or manufacturer; i.e., Tremec) to custom-gear the transmission itself without it turning into a budget NASA would be proud of.

As I'm looking at these kits, it seems parts are going to run $4,000 - $6,000, which is not pocket change, but it isn't going to break me. Then you have labor to install. If it costs another, say, another $4,000 to modify the transmission to suit my driving style, I can't do that. For a build like this, I already have to set aside additional thousands just as a contingency if something in the kit breaks. So I'd just have to use what comes in the kit box and live with it. Just about anything would be better than what's in the car right now; I hate 3-speed automatics with a passion, every one of them.

Hopefully that's enough information about what I'm looking for. Now I need to find out whether it's possible, and if so, who is the best person to provide it.

Jess

 

Why not get the gearbox replaced in the xjs and buy an xkr. The x150 has the paddle shift from the factory and the x100 has a kit available. Less hassle less cost lots of pleasure from both cars all above boxes ticked. Just a thought.

 

I think you figures are right there with the prices. I can do this type of conversion at a lower cost than anyone else becasue I make my own clutch pedal and modify the pedal box in house. That saves almost a grand.

I have an XJS with a six speed in my possession right now. You can drive it and see exactly why you are getting if you want to take a trip to the Big Apple. Trans install is done but its still here for suspension and interior work.

I PM'd you my contact info.

 

Oh man, several reasons...

1) Paddle shift, to me, is boring and not a true manual option. No footwork involved, which is part of the allure of manual transmission. I've got an XF with paddle shift in it and I don't hate it, but I definitely don't love it (I love the car, just not the gearbox). Feels like a video game.

2) I've had an XK8 before. I just don't think the car suited me, compared to my other stuff.

3) Cost. I've got other projects running and dropping a chunk on an XKR isn't doable. Plus I'm out of room as it is.

Jess

 

I got your info; I couldn't tell whether you were offering to serve as a parts source or if you were wanting the conversion. I'm in Alabama, and I want it done locally. Transport costs would more than eat up the cost savings of sending it up there, plus I like to put eyes on the car during the process and wouldn't be able to do that from here.

Jess

 

I really don't see much if any advantage to a six speed with two OD's and 2.88 diff. unless you have a low diff ratio & travel on Wyoming/Texas type roads. My rpm @ 60 mph is 1,800 in 5th. with 3.54 rear. Other downsides are the cost and instillation in regard to the XJ-S transmission tunnel's small size.

 

Well it seems to me like a hell of a lot of effort for someone who doesn’t sound like they will give the car some welly on a regular basis. You’ve already got upto 14k on this without any snags. Drive an xkr it’s a different creature to an 8. I’ve had both . Upto you in the end though.

 

Not sure what you mean by the first sentence. If you're talking about actually driving it, I put about 5k on it last year. Three years ago, I actually commuted 200+ miles in it a day five days a week for six months. I drive a lot down here, necessitated by how remote I am. As a family, we probably put 40k-50k on our cars (split among our five total) in a given year. That's a good mix of use in my opinion.

I don't think I'll be anywhere near $14k when I'm done. It will be closer to $10k based off the labor quote, maybe $11k depending on the suspension work. The bigger issue is that if I got an XKR (or anything else, for that matter) I'd either be adding an additional car I don't have space for, or I'd have to replace something we already have. I like what I have now too much. Average price for a used XKR is going about $22k right now, so $22k plus a couple thou for the XJS repair and then leave a car out in the weather ... I'll restomod the XJS.

Jess

 

Both. I install and sell the parts.

 

I found you need to keep the overall ratio (overdrive X diff) to be 2.6 or greater to avoid lugging. With a 2.88 rear, you are already close to that. Even a 0.8 OD would give an overall ratio of 2.3, I'm not sure the engine has enough low end torque to pull that on any sort of hill.

I did a 5 speed conversion to a 1966 S Type and originally had an overall ratio of 2.38 (3.77 diff and 0.63 OD) and that was too tall. I changed the OD ratio to 0.73 to give me 2.75 and that was much better. For reference, the later 6.0 cars with a 4 speed the overall ratio is 2.66.

For maximum fuel economy pretty much all piston engines achieve a minimum fuel use at an average piston speed of 7 m/s. There are formulas to find that for the V12's stoke to figure out what RPM that average speed occurs at and see how it fits for the rear diff ratio. Doing the math, that is 3000 rpm for minimum fuel use, so the 2.88 and 3 speed combo isn't as bad as you might think. Clearly Jaguar Engineers knew what they were doing.

 

Hi Jess,

Let me introduce myself to this thread as I see our name mentioned a lot, My name is Ben and I run Simply Performance. First of all I want to apologise to Steve who may have had a bad experience with my father Jon some years ago. You are not the first person to have said this and now hopefully I can put this right! I took over the day to day running of the business with my brother about 3/4 years ago. We have changed the business a lot and it's a very different business to what my father was running, which started in 1984! You will be mainly dealing with myself, Harry my brother or Mitch who is our parts supervisor, any issues get raised to me so I hope we can deal with you effectivly. I will send you a PM Steve to ensure we can assist you in the future!

So we do a manual conversion for the V12 that used the Getrag gearbox. It has been incredibly popular in recent years. We have sold over 200 of these conversions all over the world. Shipments to the USA is not a slow as you would think. We have had 3 shipments there this year all which have arrived within about 3/4 days depending on customs. We can supply a complete nut and bolt package to assemble the Getrag onto the V12.

In our view it is the best conversion as it uses all Jaguar parts. We have done a lot of them now and we have ironed out most of the issues. We have an installation guide that I can show you Jess, it is very simple. There are some things that you have to do and I will give you a list. Our kits now are complete with new prop shafts in the correct lengths, all new service parts that are original i.e. clutch slaves and masters along with options of uprated prop shafts and clutches depending on the application. We have had a wide range of people install the kit with many still doing it on jacks on their driveway!

The Getrag is a great gearbox and we have only ever had a small hand full of issues. All of which we rectified by supplying another box as we have a range of them in stock. We have used the Getrag on applications up to 7 Litres without issues. If you are concerned about the reliability, we can supply a Getrag 290, this is supposedly stronger and was fitted in S/C AJ16 X300's along with Aton Martins as standard. The boxes are very good. I have to say I have seen more Tremecs that have broken from power of V12's and other engines than Getrags. I think with Tremecs there is always a concern of the quality of some of the new parts. Don't get me wrong, the Tremec is a good box but I think more suited to a Cobra or Kit car application. Where as the Getrag is a Jaguar box and in a lot of cases seen as Original Equipment even for some customers we have supplied conversions for that race in historic championships where originality is essential.

Overall we can supply you will a complete package. I will send you a PM with some more details as I am not sure how the rules on the forum work in terms of me giving out our email.

I hope the above has some good information for you and I hope we can assure you that Simply Performance is a trusted company.

 

Hi Jess,

Let me introduce myself to this thread as I see our name mentioned a lot, My name is Ben and I run Simply Performance. First of all I want to apologise to Steve who may have had a bad experience with my father Jon some years ago. You are not the first person to have said this and now hopefully I can put this right! I took over the day to day running of the business with my brother about 3/4 years ago. We have changed the business a lot and it's a very different business to what my father was running, which started in 1984! You will be mainly dealing with myself, Harry my brother or Mitch who is our parts supervisor, any issues get raised to me so I hope we can deal with you effectivly. I will send you a PM Steve to ensure we can assist you in the future!

So we do a manual conversion for the V12 that used the Getrag gearbox. It has been incredibly popular in recent years. We have sold over 200 of these conversions all over the world. Shipments to the USA is not a slow as you would think. We have had 3 shipments there this year all which have arrived within about 3/4 days depending on customs. We can supply a complete nut and bolt package to assemble the Getrag onto the V12.

In our view it is the best conversion as it uses all Jaguar parts. We have done a lot of them now and we have ironed out most of the issues. We have an installation guide that I can show you Jess, it is very simple. There are some things that you have to do and I will give you a list. Our kits now are complete with new prop shafts in the correct lengths, all new service parts that are original i.e. clutch slaves and masters along with options of uprated prop shafts and clutches depending on the application. We have had a wide range of people install the kit with many still doing it on jacks on their driveway!

The Getrag is a great gearbox and we have only ever had a small hand full of issues. All of which we rectified by supplying another box as we have a range of them in stock. We have used the Getrag on applications up to 7 Litres without issues. If you are concerned about the reliability, we can supply a Getrag 290, this is supposedly stronger and was fitted in S/C AJ16 X300's along with Aton Martins as standard. The boxes are very good. I have to say I have seen more Tremecs that have broken from power of V12's and other engines than Getrags. I think with Tremecs there is always a concern of the quality of some of the new parts. Don't get me wrong, the Tremec is a good box but I think more suited to a Cobra or Kit car application. Where as the Getrag is a Jaguar box and in a lot of cases seen as Original Equipment even for some customers we have supplied conversions for that race in historic championships where originality is essential.

Overall we can supply you will a complete package. I will send you a PM with some more details as I am not sure how the rules on the forum work in terms of me giving out our email.

I hope the above has some good information for you and I hope we can assure you that Simply Performance is a trusted company.

 

Welcome to the forum Ben,

I see your intention with this post is to assist and inform and have therefore approved it.

Please see my PM for further details.

Graham

 

Well said Ben.

 

The T56 is a great option for those who want a lot more for the money. The T56 is a higher capacity tramsission and was used behind the Aston Martin v12 DB7, the V12 Vanquish and many other performance cars. The T56 allows for the use of a hydraulic release bearing that allows for more pedal feel and considerably less pedal effort.

A T56 conversion only uses 3 custom parts. The bell housing, pilot bearing and driveshaft. All other parts are off the shelf. Jag v12 flywheel, hydraulic realease bearing and clutch disc are all off the shelf and available anywhere.

A T56 convesion also allows for the use of a NEW transmission with long term parts availbilty. The Jaguar versions of the Getrag 260/265/290 are long out of production. Chances are replacement gears and other parts unique to the Jaguar ratios will be out of production soon.

A T56 conversion also allows the transmission input shaft to go directly into the back of the crankshaft. And on the 6.0 the use of a full roller pilot bearing is possible for the ultimate in shift speed and quality.

Of course the T56 is a Six speed. Neither the T56 or the Getrag offer ratios that are ideal for a 2.88 diff. A 3:31 or 3:54 is ideal for a close ratio T56. Together with the hydraulic release bearing they offer a no-compromise high performance driving expericne that can not be matched by a collection of used parts and adapters.

As for cost... the T56 conversion uses all new and low cost easily sourced still in production parts that are stocked dometically and ready to ship at a moments notice. A used Getrag 265 sells for about 2000 domesticaly, by comparison an all new T56 Magnum costs 3300 with high avaialabilty and 700 ft/lb capacity. All the other parts for the T56, like flywheel, release baring and clutch disc are very low cost. That's a no brainer.

Also using a T56 provides you with many upgrade paths... If at some point the V12 needs to be replaced for some reason lets say an LS or conversion is desired the T56 can be reused simply but fitting an LS bell housing. Additionally there are many high performance aftermarket release bearings and clutch disk marterial choices to help dial in your project. For example with a T56 you can choose a smoother stock style clutch disk or race style 6 puck type. Same thing with the release bearing...you can choose a billet race version or a more pedestran stock piece.

T56 Conversion is a low cost no compromise solution.

 

I'm guessing the trans is just fine. I've got a sweet problem when cold I have to rev the absolute **** out of mine in reverse to get it to move. I feel like I am killing the trans. Once warm though... can shift in and out of reverse fine. Low fluid is my guess on yours and mine.

 

Ben, I must admit I no squat about the Getrag 290 transmission. As for the Tremec TKO 600 please explain why it is the trans of choice for Dodge high pro like The 707 HP Hellcat, countless pro street car's, ie:crate 502cu BB cars, 426cu Hemi's, etc. These engines are putting out well over 500HP & enough torque to tear the car in half . The review's I read, the TKO 600 make the GM Muncie M22 "rock crusher" look weak.
You saw numerous Tremec's "broke up with a power of the V12". What kind of V12 power are you saying? Comparison test reviews on these two trans' in cars that exceed 450 HP & 500 tq lbs would be the only thing that would sell me on the Getrag vs the Tremec . BTW I have nothing to do with Tremec, Getrag, GM or ANY other Co's

 

Yes, check fluid, of course. But your trans might be suffering morning sickness--- old, hard internal seals that don't work until they've absorbed a bit of heat, at which point they soften a bit a come back to life.

Also check the seal to the filter. With age the filter neck-to-seal joint becomes weak and allows more air than fluid to be sucked up. Sorta like re-priming a pump every morning

Cheers
DD

 

 

Its fair for me to admit that I do not know much about the Tremec transmissions. The transmissions that I have seen that have been damaged were T5's i believe. I know there are a lot of models for Tremecs but my understanding was it was the T5 that had failed. The ones that I saw twisted on the input shaft. I have no doubt that Tremecs are a good gearbox and a great off the shelf option for a lot of cars, however, its not a Jaguar or period gearbox. Either way there are different options depending on which way you go. We lean to the Getrag and we are bias for the Getrag but there are always other options. Getrags are much more common here in the UK and also mainland Europe as its the choice of gearbox for BMW (don't be confused they are a different model of box) so I guess there is more confidence and availability over here. Where as the Tremec is more common in USA. The only thing with the Tremec is you have to fiddle with the clutch, tunnel inside the car and fit a lot of non OE parts, whereas with the Getrag you can adapt it using all original fittings, pipes and prop shafts with just a 15mm conversion ring. Its a choice of preference but the question of whether the Getrag can handle the V12 shouldn't be a concern.