Lock Up 727

I'm not sure how but this write up has become a bit of an epic so nip off and grab a cuppa, make yourself comfortable, and I'll be waiting here for you when you get back...

"I have a dream" went a well known speech. Well so do I, but it is tempered by the words of an equally well known song, "If I were a rich man...", and so my restoration of 136-8779 has been as and when finances permitted.

The car is sound structurally, but cosmetically it needs some work. I have spent the last 5 years sorting out, and where possible with modern materials, improving the car to the point where it is mechanically A1, and so this year was going to be paint and bodywork.

This was until just before the West Bromwich show when I got into a tussle with a new BMW 7 series. I couldn't let the Jensen name down, and 136-8779 didn't, but I fried the gearbox in the process.

I was mulling over the options for a replacement. In keeping with my philosophy of improvement where possible, I wanted to improve over the original 727. The first thing that sprang to mind was an overdrive 518 like the one we had fitted to Steve Payne's car.

The problem is that the 518 is an excellent piece of kit, and like all excellent pieces of kit it's expensive and would wipe out my paint budget. I consulted Steve Payne and Chris Miller for advice.

Steve "Satan" Payne's went something like this; "Go on, you knoooooow you want to"

Chris "Chancellor of the Exchequer" Miller went something like this: "How much!"

I consulted Richard Calver's brother, Phill "Rastas F Ferret" Coltman, in Australia regarding a GM 700 4 speed and lockup box. I had spoken to him when the came to the UK last year about this conversion. It seems it is a good conversion in Australia as it is a very common gearbox in Aussie GM cars, and rebuild and shift kits are cheap (the GM700 is designed for small blocks and needs a lot of upgrades to handle big blocks).

Picking up a GM 700 from a scrap yard and rebuilding it is a cost effective option in the US and Aussie, but as they are not readily available in the UK it means getting one imported, and it then becomes the same price as a 518.

It was around this time that Zac Marshall had posted on the JOC forum that he needed a new torque converter, and he had heard that there was a "Lock Up" version of the 727. In standard form the 727 acts like a "slipping clutch" in a manual car, increasing the engine revs, blunting acceleration, and generating gearbox-wearing heat.

A lockup version has a mechanical clutch which "locks" the torque converter, making it behave like a normal manual car, and would do away with those problems (*see Chryslers description at the bottom of the page. Chrysler set lock up at 27mph, but the recommendation is that this is set this to 40mph to stop the engine bogging down)

You cannot fit a lock up torque converter to a standard 727 as it requires a different valve body to engage the lock up clutch

This got me thinking and I started looking around the internet to see if they were still available. I sent lots of e-mail enquiries, but got the same response: "Haven't seen one of those in years"

I had pretty much giving up hope, until I got a response from Greg Ducato at Phoenix Transmissions Products saying yes he could do one for me (Greg was at pains to point out that they are NOT the phoenix transmission on E-Bay). I had another look at the Phoenix website, and noticed the 2 year or 24,000 mile warranty, which seemed good.

I mailed Greg again and asked his experience with the 727 and he replied he had been involved in the 727's used by Aston Martin, and that he had spent time at Aston's home in Newport Pagnell developing the gearboxes for the Zagato.

We agreed upon a specification (capable of 500bhp, 500ft/lbs torque,) I placed the order and asked Greg to take pictures of the build and testing. He mailed me first to say he had found a re-build able lockup 727 (in a scrapped Big Block powered 1978 Chrysler Newport) and work was underway.

Greg mailed again to say that the gearbox they had found was a factory high performance model, possibly police spec, with 4 pinion gears and a 4 clutch high drum. The standard unit only has 3 pinions and a 3 clutch high drum, so this box would have much more holding power. Added to this would be modern high performance bands and clutch materials.

In Greg's words "It's a great foundation to make a skank into a high performance beauty"

The fitting is a bit like fitting a 518, but with less hack sawing, and I was going to say easier than on a German building site, but as it turned out...

As the box had been flown to Birmingham airport, which is only a few minutes from Chris Miller's house, we decided to do the job there. The summer which has been awful so far decided to be kind to us (well they do say it always shines on the righteous :0)

I had gone over to Chris's place the night before to get everything ready, and we had retired to the local Indian restaurant for a huge slap up curry, and then to the pub for a few pints of Adnam's best bitter. This was going to prove to be a mistake the day after...

Top box fitting tip. This is what you need to reach what became know as "The Satan Bolts", which are the lower of the four bolts around the bellhousing, one of which holds the dipstick. These are "Wobbly" ended extensions, so it was basically like trying to undo bolts from inside the boot of the car with a piece of string!

Knackered, oily, old piece of junk on the floor. The old gearbox is next to him. I'm not sure if it was the exertion of wrestling out the old box or the effects of the beer and curry that had got to him :0)

Isaac Newton and his marvellous invention of gravity helped a lot getting the old box out.

I took the opportunity to reinstate the original radiator cooler as well as a separate air cooled cooler as well as to help things stay cool.

We tried to fit the new box, but when the torque converter was touching the flex plate the bellhousing was still 1/2 inch from the engine block. We took some pictures and e-mailed them to Greg at Phoenix. We tried everything to get it to fit, but no joy.

Chris is reduced to a burbling village idiot, taking to using an empty cake box as a hat after the trials of the day. The cakes had been used as a massive sugar rush to keep us going after the bacon had worn off. This was an echo of the fitting of the gearbox in Germany as we had bought apple strudels out of a vending machine at the train station for the same reasons.

It was late on Friday night and we could do no more, so we headed off to the local fish and chip shop for a big feed of fish and chips, fried chicken, and shish kebabs (we had been grafting for 13 hours!) This was then washed down with copious amounts of Bank's mild ale.

We would start again on Saturday morning, if I could get the box off Chris's head...

Meanwhile, over in Oxfordshire, Steve Payne was fitting a 518 for a friend in the JOC, so we chucked the 727 in Chris's car and went over as we needed to find out why the converter wouldn't fit.

We tried the 518 torque converter in the 727 and it fitted fine, but the 727 torque converter wouldn't fit into the 518 (other than the 727 having the starter ring gear fitted to the converter, and the 518 having the starter ring on the flex plate, the 518 and 727 lockup converters are very similar so they should fit either box)

We passed this new information to Greg, and the only conclusion we could come to was that the torque converter had been damaged in transit and was not sitting far enough down the shaft. They had fitted the torque converter to the box 3 times at the factory for testing on the dyno, so we knew it was ok when it was shipped, but just wouldn't fit now.

Greg immediately got to work making a new torque converter for me, to be sent free of charge as part of his excellent warranty. I cannot praise Greg highly enough for his support and service during the building and fitting of the box. He is a top bloke.

Steve then pointed out that as we had come all this way, and there was no more we could do on my car, we may as well help him fit this 518.

Obviously the psychopath with the forklift truck who shipped the first one had a day off.

After the first attempt we both ended up with sore necks from being under the car all day so we made a special tool for the job.

We fitted the box in the time honoured fashion (lot's of tea, coffee, bacon butties, effing and blinding, having fits of despond, then wild elation when we solved the problem, and finally years after buying it, using for the first time Chris's pipe flaring tool).

We even had to use what Greg referred to as the "BFH" (Big ******* Hammer), or what we refer to as "The Fine Adjustment Tool" Hope that wasn't to technical for you :0)

It was in, and filled with Mopar ATF+4 (this is Mopar's high performance ATF and is essential in 518's. As this lockup 727 was full of high performance goodies I used it in my car), so I took it for a road test.

My biggest concern when speccing a box to handle 500bhp-500lbs/ft was the shift quality. I didn't want harsh shifts at all. I needn't have worried as it behaved like a standard 727 in that you hear rather than feel the gear shifts. Even on full power kickdown gear changes you can hear the shifts are much faster and firmer, but not feel them.

The 200-300 drop in RPM is not spectacular, but gives around 3-5% saving on fuel. If you want really long gearing you need a 518. The real benefit is the throttle response. Whereas previously you pressed the accelerator and the revs would climb but the speed stayed the same as the torque converter slipped, now it drives like a manual car with instant speed increase and much sharper throttle response. I have had to unlearn 5 years of Interceptor driving as I have had to learn to use less throttle because of the improved response.

If you are after the ultimate in low rev cruising, and maximum miles per gallon, then you need a 518. It drops the revs by 200-300 depending on speed (or adds 5mph for any given RPM over the non lock up version).

The big difference is cost. landed in the UK this 500bhp monster cost the same as a Standard 727 rebuild from a UK supplier (non lock up, low performance). I had to add import duty, so it has cost me an additional £250. A small price to pay for such a high performance box, and easily recoverable cost wise in the 3-5% improvement in fuel economy.

* Chryslers description of the 727 Lockup Gearbox

"New for 1978 was a new lockup torque converter system for the TorqueFlite automatics, which, like its Packard and Studebaker predecessors, replaced the normal fluid interface in the transmission with a mechanical one. That saved gasoline and increased usable power while running the engine at a lower speed to reduce noise and wear, and has been a feature of transmissions ever since. The lockup feature took effect at speeds greater than 30 mph.

Chrysler published this description: “When accelerating from a stop, TorqueFlite continues to use the torque converter for power and smoothness until road speed reaches about 27 miles an hour for V-8 engines and 31 miles an hour for sixes-then, as the transmission up shifts from 2nd to 3rd gear, the new clutch locks up the torque converter so there is a direct mechanical drive through the transmission. Normal slippage in the converter is eliminated, engine speed is reduced and fuel economy is improved.”

When up shift occurs at lower road speeds (below 27 mph for V-8s and 31 mph for sixes) the lock-up clutch engages when the drive shaft reaches about 850 rpm for V-8's and 1100 rpm for sixes.

When up shift occurs at higher road speeds the lock-up clutch engages simultaneously with the up shift.

The lock-up clutch disengages automatically under
part-throttle downshift, full-throttle downshift, and the drive shaft reaches 850 rpm with V-8 engines and 1100 rpm with sixes while slowing down".