LT77 bell housing etc

[ReturntoJag]

I am looking at buying a series 2 2+2 auto. My plan would be to do a manual conversion. I am interested in the possibility of using an LT77 5 speed box. This was available on the XJ6 series 3. However examples out of the XJ6 are less common than those out of other cars.

Did the XJ6 version use the same bell housing as any of the other versions?

Is the first motion shaft length, splines and spigot the same as on other versions?

Interestingly some internet sources say the LT77 box was developed from the Jaguar 4 speed box.

Thanks,
David

[abowie]

I can't speak from experience because to be honest I'd never heard of the LT77 so I can't comment on specifics. But I've not heard it being mentioned as a choice for putting in a 2+2.

https://www.ashcroft-transmissions.co.u ... /lt77.html are a UK mob who seem to rebuild LR and RR boxes; these used the LT77 boxes apparently. They might know.

Having had a look, it does seem that it was available in 6 cylinder S3 XJSs, so it's probably doable in that the bell housing for that particular should fit the back of your block, if you can get one. Where you may run into trouble is in the tunnel diameter and box length/gearstick position. The bolt pattern on the box in the link above doesn't look much like an E Type bell housing either.

Original 2+2 boxes are not too hard to come by, and the 4 speed all synchro box in good condition is quite OK to drive. The benefit of this is that it fits the car and all the parts to do so are available. I have 2 cars with these boxes and like driving them both.

Moving on, the extra tunnel length of the 2+2 will accommodate some Jaguar overdrive boxes. Again I have never done this although there are those on this forum who have. Personally that strikes me as an attractive option but I speak from a point of view of zero experience.

Otherwise probably the cheapest 5 speed option is to fit a Toyota Supra box using a conversion plate and an original Jaguar manual bell housing. This option is far from perfect as it may involve significant panel work. I've not done it myself but have driven a S1 car with a Supra box and it was very good. Again many others have done this; plenty of info on this forum.

Once you have got to here you are in the realm of the bespoke aftermarket options. I have a (now unavailable) JT5 box in my 3.8; it is very good. There are a couple of copies of this box available but they are pretty costly. These are mostly based on the Borg Warner T5 box, and all seem to have had problems either in design, QC or in after service. See the archives... There are also a couple of "bespoke" boxes designed specifically for the car. These seem to have very small numbers of units in service or are unobtainable as separate items.

Sorry for the long and probably not enormously helpful post. There's loads of stuff on this site about 5 speed conversions.

[abowie]

Searching; user Skiday has done what you propose.

Search for his posts between 2011 and 2018.

[PeterCrespin]

Developed from the 4 synchro? ‘Interesting’ but wrong, I’ll wager. Don’t believe everything you read on the internet :-)
The LT77 was a Leyland box used on Rovers, Triumphs, Land Rovers and Sherpa vans etc. none of which would bolt onto an XK engine. Jaguar didn’t use it until 1979.

The splines are different, the single rod selector design is totally different internally and externally and the clutch release is closer to the V-12 than any other Jag to that point.
as are the bell and flywheel. The front of the shaft runs in a needle bearing in the flywheel centre, not a blind crank bush, so the shaft is metric and probably shorter. So the differences are ‘modernization’ changes that mean the LT77 has more in common with a Getrag or Ford-type box than the 1940s tech of the various four-speeds.

Unless you have the entire above kit of parts, including the starter, I would not go the LT77 route. If you have everything and are a good fabricator I’d give it a go. The actual box is OK but there may well be ‘gotchas’ to do with mounts, tunnel clearance, stick position etc. although as it’s an auto tunnel there’s probably room. A cheap LWB 4-speed would already be a big advance over an auto and may be enough if you try one?

[ReturntoJag]

Thanks for your comments. I had wondered about the LT77 as a cheaper alternative to some of the other options. Some people are looking for a lot of money for used Jaguar 4 sync boxes, especially those with overdrive.

Peter, in saying "LWB 4 speed" are you saying that the standard 2+2's 4 speed box is different from the normal one?

Also in other posts I have seen reference to compact overdrives. Does this mean that not all 4 sync overdrives are the same?

[mgcjag]

Hi Whats your name..please try to put it with your car model in the signature area......The 2+2 4 syncro gearbox is different in that it has a longer rear shaft in an extension piece on the rear making it longer....this is an advantage as fitting a 4 syncro with compact A type o/d from another Jag model is the same length so fits straight in the tunnel......the gear lever will be in the wrong position unless you use an E type top cover.....lots of info on the forum already about it...search overdrive.....Steve.....PS it must be a compact o/d to fit.....looks like this....note the top cover is not E type

[mgcjag]

Just to add..if you go the Jag 4 syncro route you will need bellhousing and flywheel....but you need to understand what you are getting...flywheels have different teeth counts and bell housings are different..accordingly starter will need to match......Steve

[johnetype]

Yes, up to £1500 for a 4 speed gearbox with Compact A Laycock overdrive isn't cheap but by the time you add all the other parts you'll need to get a LT77 or other gearbox to fit and work you'll find it's certainly a cost effective option.

The Jaguar 4 speed box itself was the same for Series 2 and 2+2 cars, however when fitted to 2+2 cars the gearbox had an extension on its tail so that its extra length matched that of the longer 2+2 car and Jaguar didn't need to change the prop shaft. As it happens if you have a 4 speed gearbox with a Compact A overdrive on the end of it, as per the picture above, the length was similar to the original 2+2 4 speed gearbox and you don't need to change the prop shaft as I understand it.

Laycock made a range of overdrives and Jaguar used more than one type on their cars. The E type was never fitted with overdrive by Jaguar but folks talk about using the Compact A overdrive because that one has the most compact dimension suited to fitting in a 2+2 without bodywork modifications.

You can't just buy a Jaguar 4 speed gearbox and bolt a Compact A overdrive onto it as the gearbox has to have a longer output shaft with oil pump drive on it. Series 2 XJ6's came with an overdrive option (which is the box in the photo above) which is a good way to go but you need either the top cover from a standard E type Jaguar 4 speed gearbox or to modify the XJ6 gearbox top cover as Steve mentions to get the gear lever in the right place.

Realm Engineering offer the Toyota five speed gearbox conversion to fit in a 2+2.

[sbs]

I have some familiarity with the LT77 since I have a TR8.

They are relatively weak gearboxes, and not particularly loved from a "nice gearbox feel" standpoint.

The factory-claimed torque for the S2 XK engine is above what is reported as the safe level for the LT77.

The ratio between 1st and 5th is relatively low, meaning if you gear the car for acceleration in 1st you get a pretty noisy ride at freeway speeds.

I think, but am not certain, that the XK-LT77 bellhousing is unique so you'll need to source one from a fairly rare XJ6, most of which were parted out decades ago.

Some parts for the LT77 have become unavailable, and a lot of parts are only available from suppliers of dubious quality.

The later R380 which is a slightly improved LT77 improves on most of these issues, but 2WD versions are rare. When they show up on ebay they are generally out of TVRs, so you get to pay the "TVR tax".

I see two kinds of LT77 / R380s on ebay - very ratty, and very expensive.

There's a complete, unrebuilt TVR LT77 on ebay right now for £995 as an indicator.

In the US a professionally rebuilt LT77 costs almost as much as a brand new T5, which is a better transmission by all of the above measures.

[ReturntoJag]

Thanks everyone for you input. I can see that putting a Jaguar manual in would be simpler, with or without o/d.

I have had a look at the boxes currently on ebay. Many of them come without bell housings and bell housings look to be in short supply. Can the bell housing from the auto box be modified to use with a manual? Perhaps using a concentric slave cylinder as it doesn't have provision for a clutch fork?

Much of my experience is with MGBs where the separate engine back plate makes modifying it to take other gearboxes easier.

Thanks,
David

[mgcjag]

Hi David...no you cant use an auto bell housing.....plenty available from various second hand Jag suppliers..but note what i said in my previous post......also this may help viewtopic.php?f=5&t=12883&p=104581&hili ... ng#p104581 .Steve

[PeterCrespin]

Thanks everyone for you input. I can see that putting a Jaguar manual in would be simpler, with or without o/d.

Can the bell housing from the auto box be modified to use with a manual? Perhaps using a concentric slave cylinder as it doesn't have provision for a clutch fork.

Yes, I’ve got all the bits except the longer bell bolts, so save those. PM me if interested. Cheap enough to ship as quite light.

Pete

[mgcjag]

Hi Peter...your answer...Yes....is that refering to converting an Auto bellhousing to use on a 4 syncro box?..Steve

[abowie]

Should you really want to do this I have a couple of spare manual bell housings. One thing you'd need to be sure of is what the diameter of the front main shaft bearing is on your putative LR77 box so that you're sure that it will fit the bell.

They can be machined out (to make a Moss bell fit an all synchro box ) but going the other way would involve welding etc.

[V12 Epyte]

I have an LT77 5 speed gearbox c/w bell housing and clutch release arm, and gear lever from a Rover SD1 which could be for sale for £495. Unused for many years. pm me if interested
John

[ReturntoJag]

John, is that with a Jaguar bell housing or a Rover one?

Thanks,
David

[PeterCrespin]

Hi Peter...your answer...Yes....is that refering to converting an Auto bellhousing to use on a 4 syncro box?..Steve

Yes to using the auto bell with a hydraulic sliding release bearing and manual box. In my particulsr case It comes with a T 5 adapter plate but I daresay a Jag 4-speed could be used (although a Jag bell would be by far the better option for a Jag box IMO).

For a 2+2 or XJ the long T5 is as cheap as chips here, so The Driven Man offers the option of using the existing auto bell to connect the T5. The parts I have were removed from a friend’s XJ and he replaced them sith a Jag bell and a T5 adapter from Elite.

[mgcjag]

Hi Peter..thanks for the reply...thats very intetesting....did you also use a standard flywheel inside the Auto bell...Steve

[PeterCrespin]

I have an LT77 5 speed gearbox c/w bell housing and clutch release arm, and gear lever from a Rover SD1 which could be for sale for £495. Unused for many years. pm me if interested
John

Not to poop on your deal, but the SD1 bell won’t fit a Jag and nor will a standard Jag bell flyeheel and starter fit the LT77. Hence my note that IF the OP finds a complete Jag kit, ‘from soup to nuts’ as they say here, it could be worth doing the fabrication needed to fit it, Without the FULL kit from crank flange to propshaft, there will be, er, ‘challenges’ or ‘issues’ or whatever we’re supposed to say instead of ‘problems’ these days...

For someone with an auto on a budget the huge improvement and fabulous value for money is going from auto to a cheap 4-speed manual. It totally wakes the car up and there are plenty of cheap LWB 4-speeds from people who’ve fitted 5-speeds or MODs.

The extra benefit of going auto to 5-speed is there but is far more subtle and a more arguable cost-benefit compared to the massive change from two pedals to three.

[PeterCrespin]

Hi Peter..thanks for the reply...thats very intetesting....did you also use a standard flywheel inside the Auto bell...Steve

Yes, standard flywheel. I think the diaphragm clutch had no release bearing flat as the roller bore directly on the diaphragm, as they commonly do these days. A gear reduction starter happened to be fitted but as there’s only one tooth difference between auto and manual fing gear (133/134) I suspect the original starter might have worked.