Did Bristols modify the Torqueflight

[Roger Morrall]

Having discussed engines, standard or otherwise, my thoughts turn to the gearbox.

I have a vague memory that I might once have read that Bristols feared that the torqueflight would prove too sporty for a luxury car and disabled at least one feature thereof that enabled full performance and engine braking up and down all the gears. This seems an odd thing to have done, but bear with me - I quote from an article relating to the torqueflight as installed in Chryslers.

"The calibration strategy of the TorqueFlite was as follows:When the "D" button was engaged, the transmission would always start in first gear, automatically upshift into second and then direct drive or third gear. Kickdown into second gear was possible below 65 mph and into first gear below 30 mph. A closed-throttle downshift from direct to first gear occurred at 10 mph.When second gear was selected, the transmission would always start in first gear and automatically upshift to second. It would remain in second regardless of throttle opening until 70 mph, at which time it would upshift to third gear to prevent excessive engine rpm. Kickdown into first gear was possible below 30 mph. A closed-throttle downshift from second to first occurred at 10 mph. The provision for second gear operation allowed greater control in city traffic and hilly terrain.A selection of first gear had the transmission start and remain in low gear regardless of vehicle speed and throttle opening. If this position (first gear) was selected at speeds above 30 mph and below 65 mph, the transmission would downshift into second immediately and would remain in second until the vehicle speed fell below 30 mph. A that time, the TorqueFlite would step down to first gear.

The words I have highlighted are not reflected in the 410 drivers handbook and neither do they accord with my own experiences, some of which were recounted in my article Alarms and Excursions in the Alps in BOC Bulletins Nos 167 and 168.

Can anybody shed any light on this. Did Bristols modify the torqueflight in some way when it was installed in the 407 and subsequent cars?, if so how? and is it reversible?

[David C]

There are reports that Bristol modified the early, cast iron cased, Torqueflites to alleviate issues with the tail shaft bearings overheating. I am unaware of any significant changes to how the shifting operates.

There are options to change shift points with "shift improver" kits. I fitted one and later regretted it. It was advertised as giving crisper shifts and reducing slip but I found it rather jerky and more for racing than for a touring saloon.

You can also have the torque converter rebuilt to change the stall torque ratio but my feeling is that it was well suited to the cars as supplied.

[David C]

Some useful info here:
https://www.allpar.com/threads/torqu...ations.229966/

[Geoff Kingston]

I seem to recall that what they did was to disable the part throttle kick down option on the gearbox and If I remember correctly this was all down to how the linkage was set up, certainly my 603 will do it sometimes but when I changed to an Edlebrock carb on my 411 and its associated adapter kit we suddenly had part throttle kick down. I can understand why Bristol might have set the cars up like that for London traffic, but in the early 80's traffic light dash between traffic lights on Brighton seafront it was a useful feature to have, especially if a local Jensen was about, if the local Lincoln Continental driver lined up against us though we were in for a hiding, that thing could shift off the line so generally we used to let him go just to see his efforts to haul the leviathan in before the next set of lights.

[peter dowdle]

I refer you to a post started by Paul Robert on 1/5/20 about 3 to 2 part throttle kick down. The modification apparently made by Bristol on later 411 and 412s was to delete this kickdown as being inappropriate for a refined touring car. I first saw mention of this in a 1975 Motor magazine. The Roberts post clearly covers the issues. My 411 didnt have kick down from new but when added vastly improved the drivability of the car.

[Kevin H]

Originally Posted by peter dowdle

I refer you to a post started by Paul Robert on 1/5/20 about 3 to 2 part throttle kick down. The modification apparently made by Bristol on later 411 and 412s was to delete this kickdown as being inappropriate for a refined touring car. I first saw mention of this in a 1975 Motor magazine. The Roberts post clearly covers the issues. My 411 didnt have kick down from new but when added vastly improved the drivability of the car.

Here's a link to the post torqueflite part throttle kick down - Bristol Cars - Owners and Enthusiasts Forum

Paul Robert concluded that Bristol didn't delete anything. It was just that the transmissions used by Bristol didn't have the 3rd to 2nd gear part throttle kickdown in the first place.

If this is correct and Bristol said that they deleted/disabled that function, then it may have been a bit of clever marketing to cover up the fact that they were using older transmissions.

[peter dowdle]

Kevin you may well be right. Certainly by the time the 411 mk5 and 412 were about the current Chrysler boxes definitely had kick down.

[Stefan]

These gearboxes seem inaccessible but I'd suggest getting the relevant Chrysler Master Technicians Conference handbook on eBay (yes, other sites are available).
These are super readable and tell you how to service, troubleshoot and adjust your 'box. And there are cartoons too..,