411/412 4 speed conversion

[peter dowdle]

This article is worth a read Chrysler A-518 Overdrive Transmission | Hemmings Motor News

[devadmin]

Originally Posted by peter dowdle

This article is worth a read Chrysler A-518 Overdrive Transmission | Hemmings Motor News

It's not worth the work and fairly serious modifications unless the car is your daily driver.

[Kevin H]

Peter,
you do almost have to be at full throttle to achieve kickdown, same on every car I've driven with a 727 Torquelfite.

However it definitely shouldn't still be in third/top gear when you're coming out of a roundabout. Sounds like your tranny isn't set up properly, or perhaps your fluid level isn't right, that can cause odd behaviour (needs to be checked with tranny warm, with engine running, in Neutral).

There are lots of different modification kits for the 727, but I would get it working properly before you contemplate fitting one.

Having it kick down earlier may not be that desirable, especially going round a bend in the wet

[Philip]

About time someone stuck a (more) modern gearbox like a 6L80 or W5A580 in one now there are aftermarket controllers ...

[GOFFJASON]

I have liaised closely with the firm in the US mentioned in the article link, and ordered a complete conversion package from them. New A518, lock up converter, conversion kit with vacuum switches for kick down and overdrive, and adaptor plates for mounting to the RB/BB engine block.

As with my suspension refurbishment, I will keep a good photographic record and post the experience on this forum. Good, bad or otherwise I will be as objective as I can. Just give me a few months, as the nights are cold at the moment.

Having spent may hours under my car I have thoroughly measured the areas around the tunnel and crossmember. Whilst I expect to make changes to the transmission mounting and some relief of the tunnel cover, I do no think changes will be too extreme. keep you posted....

[peter dowdle]

The mistery of the lack of kickdown has been solved.In about 1971 the 727 had a new control body fitted that provided what crysler called part throttle kickdown. My mk 2 was built in 1971 but has an eatlier box ( probably old stock).mk 3s and latter would have the new control valve. It is possible to have the earlier boxes modified. This is currently being done to my car.