Jensen heritage for the next generation

Automatic Transmission

Dear Diary discusses the automatic transmission fitted to Jensen FF chassis number 119/191

From the Jensen FF Mk1 sales literature: “Torqueflite 3 speed automatic transmission with torque converter. Overriding hold controls and Kickdown on first and second gears. Floor mounted control with illuminated indicator. Transmission oil cooler incorporated in radiator bottom tank. Overall ratios 1st 7.50 2nd. 4.44 Top 3.07 Reverse 6.75″ Ferguson formula 4 wd unit. Open propeller shafts. Hypoid final drive units, axle ratio 3.07:1”

NB. On my 1969 Mk1 FF the automatic  transmission oil cooler is located in the left hand side tank. (there are no top and bottom tanks only side tanks)

dcp01874 1 Dcp01952jff7 3

Photo 1 is of the original automatic gearbox sump pan. No drain plugs, so mounting bolts need to be removed to drain oil am now using Castrol Dextron 3 instead of the originally recommended Castrol TQ. Photo 2 is the auto box filter and gasket set as bought from customville – £8.52p+£8.95p postage +vat = £20.53p. I have now bought a deep transmission pan from “Jegs” in America as they didn’t seem to be available here in the UK Cost- £45.99 + delivery. I will have this fitted when I get the transmission repaired ( beyond my facilities and abilities) . Photo 3 shows the new deep sump now fitted. This was done at the same time G Whitehouse Autos Ltd reconditioned the auto box (Nov 2002 see below).

I asked the Jensen List:

My FF was stored for 14 years. Automatic transmission oil was a nice colour when I checked it. Changed the oil anyway and put Dextron 3 in. Recommissioned the engine and have only manoeuvred the vehicle on the drive (three times). Auto refused to pick up in reverse the last time. Checked the oil and it is now burnt and dirty. My conclusion is that the auto box has had it. Where is the best place to go for a reconditioned box or to get this one reconditioned? Anyone any recommendations? Personally I’ve never removed an auto box, and given it’s an FF, I’m a bit hesitant about doing it at all. I’ve spoken to some of the American specialists but they are hesitant about doing an FF. All advise gratefully received.

Advise from the Jensen List was:

1) On the FF, unlike the interceptor you can’t drain the torque converter whilst it’s in the car. You can only flush it through.

2) After the lay up the whole Torqueflite is being cleaned, it does not necessarily mean that the box is shot. One horrible problem that you might have is water in the box – that is usually terminal. Don’t forget that the radiator also contains the gearbox oil cooler and many people think this is a recipe for disaster if the integrity goes and water gets into the oil – always a possibility after a long lie up – if it does happen it is absolutely vital to drain the box immediately. Rebuilding a box is not all that difficult – I had the burnt smelly oil problem in my FF, and because of the extra weight and the extra FF box this is always going to be a problem. I had mine done by a gearbox only specialist in Crewe.

3) Over hear, we call it morning sickness. Usually the problem is no reverse in the mornings when the seals are cold. The seals just get hard with age, whether driven or not. The fix shouldn’t be terribly expensive if it is only the seals. My car has been sitting two years and I won’t be surprised if I have the same problem. Well ,I experienced the same 20 years ago, but I drained 2 times more, and suddenly the Autobox worked perfect again. The reverse was the problem for me too. I don`t know, but it is worth a try, at least.

I also discussed it with one of the FF specialists who advised as follows:

1.There are two band adjustments available

a) Dcp01953 Reverse and top.. Drop the oil pan,remove filter (B42 kit is needed-has filter and sump gasket) Band adjuster has lock nut and square headed adjuster. Undo lock nut and tighten the adjuster until it nips (goes tight) then back off one and a half to two turns and tighten lock nut

b) ..Dcp02219 Other gears. Again band adjuster has lock nut and square headed adjuster. Located on left hand side of box just above cooler pipes. Adjust as for (a) above.

In the end I managed to get some sort of reverse action but had to wait a few seconds after putting it in reverse before it picked up. Reverse was also very jerky if I had to back up my drive which is on a slope. The final nail in the coffin was that when I took the car for its MOT, and bearing in mind this was its first long journey I discovered that when the autobox went into top it would slip badly. This obviously wasn’t apparent when I was just manoeuvring on the Driveway. I later discovered that reverse and top use the same clutch mechanism in the box and faults often affect both as appears to be my case

I was advised that a rebuild was necessary and that it was best to get the original box rebuilt as they can be different. I was told that Chrysler modified several of the internal components of the 727 box specifically for their high performance versions of their V8. And that the Interceptor and the FF had the HP 383. So the Torquflite from an ordinary 383 would not behave properly

I asked the list again about getting my automatic transmission fixed:
A few months back I had a problem with my Torqueflite auto box. Reverse would slip. At the time the car was only capable of being manoeuvred on the drive as I was just recommissioning it after 14 years. Thanks to help from the list, after changing the oil and filter and whilst the sump was off, adjusting the tension on the reversing band, reverse was re established. Now after passing it’s MOT it’s on the road, but it slips in top. I’ve adjusted the band adjuster on the outside of the box and the carburettor links without luck. The autobox works fine if held in 1 or 2. When it starts to slip I’ve pressed the accelerator down and kickdown works.

Dcp02231 In desperation and contrary to some advise I’ve also bought and used some ” Tranny Honey” from Customville , which is supposed to swell internal seals a little, and therefore help maintain appropriate pressure differences inside. This hasn’t worked either. I think I am now only left with either 1. Getting the autobox overhauled at £800 (plus £400 to actually remove and refit the box) or 2. Buying a new box from America, which I am told will be about £800 anyway and having that fitted. If the list has no ideas on what else I can do to stop this slipping in top, does anyone have any views on reconditioning as against a new box and or who might be best at doing either of these in England. Now I have got the car running and passed an MOT I am desperate to use it.

Their and my responses were:

1) Been there… In my experience, a 727, which is otherwise well serviced, but slips in top, needs an overhaul. Bad news, but the effect of the overhaul is worth the price. Sooner rebuild your own tranny, as it is probably cable shift Torqueflite, and later 727s will give you linkage challenges. In the rebuild, I recommend the B&M Shift Improver Kit for longevity and snappy up changes.
2)My SP gearbox is being rebuilt by Duncan Watts, who trades as Crewe Racing Transmissions a.k.a. Scatpack. He can be contacted on 01270 580637. I spoke to various people about the gearbox and he was the person that most people recommended. He also gave one of the cheapest quotes for a standard box (650 GBP including removal / refit). See He has also rebuilt FF transfer boxes before, so does know the FF.
3) Thank you for the recommendation for Duncan Watts. He is a very impressive chap. He talked, knowledgeably, about shift improver kits, higher capacity sumps and new the differences between the interceptor and FF box removal. He quoted me £750 GBP for the rebuild and removal/refit. He recommended a rebuild of the existing box rather than fitting an off the shelf recon one. Getting it there is going to be my problem (driving it in 2nd all the way from Stratford Upon Avon to Crew (3 hours?) might be pushing it a little? and its £300 for a transporter (one way). Cropredy Bridge quoted me £1,300 GPB for a replacement recon box /removal and refit and G. Whitehouse Autos of Dudley in the West Midlands quoted £1,200 GBP’s. I’ll do a little more digging before finally deciding, but at the moment my heart and wallet are with Duncan Watts.
4) Not wishing to say this on the list, but you could of course do a few miles from home in 2nd, and then call the AA/RAC with a “transmission problem” who would then transport your car to Crewe – be worth joining just for the saving this time and you would get future cover into the bargain. Not very scrupulous, but maybe worth a thought?
5)If you have home start you may be able to get the AA / RAC to take it. I asked them (RAC) and explained that I couldn’t find a specialist locally and they agreed to take the car up for me.

I asked the list about cooling the transmission fluid and about shift kits.
1) I am having my autobox reconditioned. I have asked for separate oil cooler to be installed in front of the radiator and for the original connections to the radiator cooler to be disconnected. I wanted to prevent any possibility of water contamination off the new autobox. A friend has suggested that this might not be a good idea because he thinks the original radiator/water system actually acts as a temperature stabilising system to the benefit of the autobox.?
2) Someone suggested the use of a B&M shift kit to improve the life of the box. I understand it will also improve the acceleration of the car. I am concerned about the shift becoming harsh and that the improvements promised by these shift kits are just sales hype. Anyone any views.

The responses were:
1) A) In your case the type of tansmission cooler your talking about is junk all your going to do is a block a portion of the radiator and heat the trans fluid significantly higher then running through the radiator. On my race car I had the old ineffective radiator mount trans cooler on it and the trans temp went up 52 Degree’s and the Coolant Temp went up 44 deg. When I changed it all around and moved the trans cooler to back of the car with a 1250CFM fan attached the Trans temp went from 212 to 153 when it was up front the trans temp was 260. So I really have no faith in those units from my experience. B) Automatics are built with a certain amount of slop into them. Car companies do this so the shift is not as harsh as it should be to keep customers happy. The B&M kit does what it says it improves the factory shift to where it actually should be and the shift kit does add life to an auto trans. But they do tend to shift harder and faster then what you use to and under power they will usually chirp second gear. So the shift does become harsh but it becomes like it should be IMO and the B&M is not the best kit to buy the Trans Go kit is a much better choice IMO.
2) I agree with your friend. Moreover, if you arrange the hoses in such a way that the hot fluid from the transmission goes first to the external cooler and then to the radiator cooler, you will probably add a good deal less heat to the coolant in the radiator than with the stock set-up. My early Interceptor III has been running with that arrangement for three or four years now, and I’ve found it very satisfactory. I don’t know about the B & M shift kit. Ask the man who owns one.
3) A) I am interested in doing a performance road only transmission rebuild for touring use in an FF. The Mopar shifter kit says “For serious performance/racer.” I want to use the car in slow traffic without detriment. I don’t want the kind of grief you get with a high lift cam & lots of overlap in London traffic. Is the kit OK in this respect? B) The Chrysler/Mopar shift improver package says for non-lockup use only. It consists of a thin-drilled plate (presumably fluid signal re-programming), pin, ball & gaskets. Does the drilled plate replaces an existing plate or get sandwiched in? Is it only for non-lockup use because the converter clutch might be damaged by firmer shifts, or are the drillings different? If just the drillings, can I open up an extra hole I wonder??? Out of interest are the locking 727s strong/reliable enough to be used in drag racing? I guess that I can use stronger race bands without any negative impact on behaviour? Also, there is a 5:1 ratio Mopar kickdown leaver. Does this just make kickdown happen faster??? Finally, when the 727 front seals go (many seem to be now after 30+ years and the hotter weather), are there any warning seeps prior, or can a perfectly oil tight but old front trans seal just pop without any warning? C) 119/011 has an aftermarket cooler fitted by a PO, and this has been fine.
4) Some people on this list don’t agree with this suggestion (Hi Bill!) but I put a larger sump onto my Interceptor. The new sump has a drain plug (the original does not), and, most importantly, the new sump has cooling fins. The sump came from and cost about US$120.
5) Yes! Yes! I did the same thing on my 73 Interceptor, too…. If it is a Mopar (Chrysler) engine, Summit should have one that would fit… Comes as a kit with extender parts for the deeper placed filter, new filter and fittings and best of all…the thing has a drain plug.
6) Yes! A larger sump is also a good idea. The one drawback I see (every time I look under my Interceptor) is that the transmission pan is now the lowest part of the undercarriage…transmission pan skid? (My pan is the pressed steel deep pan kit from Mopar Performance)
7)Like you I have no empirical data one way or the other. However, the
fact that it has cooling fins and 2 more quarts capacity. Having a drain plug sure is handy, too. It hangs a little lower, but so far I haven’t had any problems hitting things like speed bumps. Do it help? No idea. But it sure can’t hurt.
8) OK, Lads, I’ll wade in here, having fitted a MOPAR deep tranny sump on the rebuild of my 727 in 1983. I think Dave alludes to the right thing- the deep sump is disaster insurance, and may marginally aid cooling. Certainly, I have had good service from my rebuilt 727 (coming on two decades…), but it makes no difference at all to the performance. The B&M kit, though- THAT made for fast, firm shifts.
9) A) From my experiences with Mopar powered vehicles (about the only vehicles I have experiences with) the following is what I believe to be true: Always run the transmission cooler lines through the radiator. Even temperature control is what keeps your transmission happy. Millions upon millions of vehicles were and are produced this way and they work great. Car companies pay a lot for their engineers and (me being one) I tend to trust them. At least I don’t consider what they do to be “rubbish”. Rapid changes in transmission oil temp (by running an oil to air cooler) will serve to increase the transmissions oil viscosity to unacceptable levels in the cold and will allow temp spikes and the like when hot. The radiator heat exchanger (oil to water) is the best way to maintain temps evenly! An extra cooler after the radiator will serve to scrub a bit more heat from the fluid on the way back to the trans, which is good! When in doubt, check out a Hemi powered car (70 barracuda is a good one!) transmission cooler routing. Chrysler bet the farm on that system in the 60s! B) Shift kits are a good thing when done properly. They are a bad thing when done improperly. The 727 loves a good shift kit be it Mopar, Transgo, level 10 or home-brew. A lot of transmission shops go the home-brew way because it is so simple. The Mopar Performance Kit is easy to install and the base level version is immanently streetable (I drive on one virtually everyday, in my 72 barracuda, Jensen Interceptor or 98 Dodge Dakota R/T pickup) I run shift kits in all my autos and the feel of a quick “snick” into gear beats the slow “fall and slip” into gear of the Jensen stock trans. Mopar made many different versions of the 727 for different applications. Jensen picked one of the stronger ones for the INT, but also the softest shifting (target market, Chrysler Imperial)… The Hemi set-up is much more appropriate for the person with the least bit of sporting blood in him. It had a much firmer shift. Temps are lower as well since there is much less slippage in the clutches during shifting. Soft shift = excess heat. The trans does not impart enough heat to the radiator to significantly effect engine cooling (check out the relative sizes of the cooling surface areas)… Your INT should run cool or something else is amiss! I didn’t see these items covered yet: C) Always replace your torque converter when replacing/rebuilding your automatic transmission. No good can come of re-using a torque converter to save bucks when its going to dump the debris from your old transmission in to the new transmission on initial start up. Also, Never try to clean a converter out.. Two other tips that I have implemented: 1) rebuild the trans with a Low first gear cluster. Adds a couple of hundred bucks to the 727B rebuild, but gets the car to move much better off the line with virtually no downside (plenty of torque to bridge the 1st to second “gap” in a 383 or 440) 2) Get the transmission rebuilt by a guy/gal that knows 727 transmissions. Another shop may do OK, but to really get a good “performance” unit, an expert is the only way. There are lots of tricks to make a unit really hold up and perform. It is one of the more popular transmissions for racing so lots of people know what’s up!

10) I have an FF2 in which I do big mileage and have done two of the conversions, namely an additional gearbox oil cooler and a larger sump with drain plug (off a minibus by the way). I have noted all the comments about not adding the extra cooler, but believe me they are not relevant to the FF. Compared with a standard Interceptor the FF engine runs much cooler, no doubt because of all the extra air space around the engine, while the gear box may run hotter because of all the extra “mechanicals” it has to drive. I should have tried to prove this but it is of no consequence now. Certainly when I got the car the transmission fluid was a very dark red – smelly and oxidised, and despite being flushed and changed several times it still went “off” very quickly. ( I do know about the oil still in the torque converter). I am fortunate that we use long life oil in all our commercial vehicles and we no longer change on a time basis. Engine oils are analysed every month and we only change when the oil has reached the end of its life. I only mention this because I have all the oils for both cars analysed when I change them (and it does make very interesting reading!) and the view of the Chemists was that the gear oil was suffering from heat degradation. I had the gearbox rebuilt and despite this the problem persisted, and it was only after a very long European trip in the heat of summer that I decided on a more radical approach. Interceptor owners need to under stand that the FF is different in several ways – the engine is set a little further back than a standard car – the engine is set a lot higher – there is a transfer box bolted to the passenger side of the Torqueflite consequently the engine/gearbox package intrudes much further into the passenger cabin and the space in the footwell is very restricted (also your feet are nearer the hottest part of the down pipe). So whether or not the FF box runs hotter is irrelevant, the cabin temperature is higher and your feet really, and I do mean really, cook. Because I had already had the radiator rebuilt I fitted my additional cooler in series with the existing one. What I said to Bremar was that if I were doing it with another car I would remove the oil cooling elements from the radiator, partly to give more water to air cooling for the engine but also to remove any possibility of a barrier breakdown and getting water into the transmission fluid. The results -cool feet – less need to have the aircon. running – no more problems with oil degradation – no noticeable affect on performance (speed /acceleration/economy) – on the road no noticeable difference in water temperature under most driving conditions. The only downside is that the engine temperature does rise more quickly and the engine runs hotter in heavy traffic; however the combination of a new sensor in the rad and good old Lucas fans (yippee!) ALWAYS holds the needle bang on N (in a fit of enthusiasm some years ago I bought Bosch fans but I see no need to fit them and the quality British manufacture has done me good for 20,000 miles – OK I’m, the lucky one). My cooler is mounted directly onto the aircon radiator and I wonder of moving it to directly behind the grille would return the engine temp to its previous levels or would turbulence be a problem.
11) What your doing is blocking the radiator and fans with the cooler. You already have an A/C Condenser up there that you are pulling air through then you added a third thing to pull air through. The farther away you can get the coolers away from the radiator the cooler the engine temp will be. In my Supercharged car I run A/C the condenser is mounted 4 inches forward of the radiator with a pusher fan on it the 4 Core Griffin rad has a Pusher on it. The Oil cooler is mounted in the inner fender with a pusher fan on it and ducted down to the front calliper. The car is a stick and has a Trans cooler that is mounted in the other fender well and ducted to the other calliper. So everything here has a purpose to cool the engine the oil the trans fluid the callipers. With the stock gauge hooked up the car reads COLD after 100 Miles with the VDO it reads about 160 sitting in heavy traffic it runs up to 180. Before all the coolers the car use to stay right around 210 and would pop the radiator in heavy traffic.
12) Along the line of the current topic of added coolers, larger pans and other Transmission improvements, has anyone had any experience with the in-line filters for transmission fluid? I was curious about the Oberg wire screen filter. Since the additional lines are there already for the separate cooler, adding it wouldn’t be a major problem. Any additional benefit is in doubt, though. It sure would help on a Ford E4OD transmission, since the Ford Service Bulletin requires any transmission service to include REPLACING the separate transmission coolers since they fill with metal shavings, and will void the warranty on any new transmission parts if the coolers are not replaced. Now That’s wear! An in-line filter in that case would certainly be a benefit, but I’m just not sure the Jensen warrants such a device. Overkill? Thanks for any input.
13) An inline filter was the factory fix for my Subaru SVX short transmission life problems. The smooth shifts generated a lot of band and clutch debris, which clogged up the little holes in the radiator/transmission cooler.
14) You might consider fitting a temp sensor on the trans radiator cooler side, to see how hot the oil really is. The main point is to let the oil in the box warm before using kickdown/driving really hard.I bought a kit that cost about 12 pounds for a Jag project that I haven’t started yet. The possibility of water contamination of the new autobox sounds more of a risk than the fluid not being hot enough. Certainly
in my cars the way I drive them now. As to the original radiator/water system actually acts as a temperature stabilising system to the benefit of the autobox.? I’m sure it did. But my FF has seen some serious use, with the seperate rad, and before I knew to fully warm the box from cold. Certainly in the Canadian market this might be an issue. But if you have the temp gague you will know what is really going on. The extra oil will mean that the system is less suceptible to peaks, but takes a bit longer to warm up. I think the safest way is to fit a seperate rad, and monitor the temp of the oil to see that it is “reasonable”. With regard to a B&M shift kit to improving the life of the
box. Perhaps they meant liveliness, rather than extend the life. The std box should do over 100K miles in continuous normal service with regular oil
changes. I don’t think longevity is an issue with shift kits. My FF has a really nice shift under acceleration, and this may just be the low stall torque convertor fitted to Mk1s or the fact that someone else fitted a shift kit. Personally, I would try one (the Mopar one would be my choice), provided that it can be undone without removing the box (when the first oil change is done if necessary).

Having considered the pros and cons aboveI decided to get my autobox fixed at G.Whitehouse autos and have a separate oil transmission cooler fitted and the piping to the radiator disconnected. The intention is that I will also fit an in line filter and temperature sender to monitor the oil and if it appears necessary reconnect the radiator in series with the external air oil cooler and/or fit a fan on the cooler.

jff3 jff5 jff7 These 3 photos were taken by G whitehouse autos during their rebuild of the transmission.

jff2 Dcp02383 Dcp02387 These 3 photos show the separate transmission oil cooler fitted infront of the radiator. I have left room for an air conditioning condenser if I ever get round to fitting A/C.

Out of this arose another question which I put to the list:

Firstly, What is the best operating temperature for the Chrysler 727 automatic transmission. I have opted to have a separate transmission oil cooler fitted at the same time my box is being overhauled (no risk of water contamination and probable benefit for the engine cooling system). If the heat exchanger can be fitted to one side of or below the radiator an additional fan is also an option. The question here is at what temperature should the fan cut in. Secondly, if there is a separate transmission oil cooler, could I? use the now redundant oil cooling facility in the radiator to cool the engine oil. It would all be part of “engine cooling” so it would just mean less cooling for the water? Do I even want to do this as engine oil temperature may not be an issue for these 383 engines. Finally would putting 60 plus psi through the radiator be to much and blow it apart? and which oil lines would I connect.

Advise from the Jensen List was:
1)Keep my racing trans running around 140 degrees F as for using the radiatior for oil cooling DO NOT DO IT. those coolers are not ment for 60 PSI and I recall you were worried about water in the trans fluid.
2)The engine oil in an Interceptor should not normally need auxiliary cooling. With the given tolerances, the oil is quite capable of functioning properly at all normal engine operating temperatures while proper viscosity choices are made. This is no racing Ferrari, after all. Also, given normal operating conditions and competent components, the transmission oil should not be exposed to any risk of water contamination. Indeed, the joint use of the radiator ensures that the transmission oil warms properly during cold operation. However, for heavy use applications, an auxiliary oil cooler is always a good idea as excessively higher oil temperatures can lead to transmission malfunction and even failure in the extreme….not that an Interceptor is normally used to tow a holiday trailer in the mountains.
The biggest pain with an Interceptor is the high engine bay temperature in slow-moving traffic in hot climates and the effects on the fuel, both in-line (vapor lock) and on timing (pre-ignition), not to mention on wire insulation and connection longevity and even perhaps engine metal temperature and subsequent transmission temperature. Further, the incidence of leaking master cylinders and possibly even the fires that have been reported might be related to long-term exposure to these very high engine bay temperatures. It seems rather intuitive to a materials scientist that given the under-hood operating conditions of an Interceptor, plastic brake fluid reservoirs should have been avoided by the “engineers” at Jensen particularly since they are located directly above exposed wiring components and an exhaust manifold.
In very hot climates, it is advised to use the 3 fan configuration that was specified by Jensen for NA delivery. This is where the Bosch solution and/or some auxiliary air-circulation solution may be a good idea. Also, one might research the POR manifold coating system with the aim of reducing these oftentimes extreme conditions.
Hope this sheds some light on the issues as I see them.

3)I think it is reasonable to point out that some correspondants live in placse where elevated temperatures are not usually a problem. Here in Southern California, engine oil coolers are a GREAT idea. In addition, it adds at least a quart to the oil capacity of the car. IMHO, the normal capacity of 10.2 imp pints is on the low side. In other words, like feeding chicken soup to a dead man “it can’t hoit”