• 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Gear change up and down
#1
73 mach 1 2 barrel 351c with c6 auto transmission

Car goes into 3rd before 30 mph and do not change down until about 10 mph is this normal.

Nige
  Reply
#2
Factory spec shift points are in the Ford shop manual. If you don't have a copy, I can post the info later.


  Reply
#3
(04-05-2019, 02:42 PM)Hemikiller Wrote: Factory spec shift points are in the Ford shop manual. If you don't have a copy, I can post the info later.

That will be great thanks
  Reply
#4
There is a small screw head in the transmission vacuum modulator that can be turned to adjust shift points. Pull off the hose and it's located inside the modulator hose housing.

Do a search on this forum since it has been addressed several times in the past.
  Reply
#5
Here you go Nige. Hope its legible enough for you

[Image: img006.jpg]

Steve
1971 Grandé
  Reply
#6
(04-06-2019, 07:01 AM)Pegleg Wrote: Here you go Nige. Hope its legible enough for you

Pegleg beat me to it...

Being a '73, you probably have a dual area vacuum modulator, which are not adjustable. You could swap it for an adjustable one to tweak your shift points up or down a couple MPH, but if yours are way off spec, you probably have junk in the governor, or more serious problems.


  Reply
#7
(04-06-2019, 07:01 AM)Pegleg Wrote: Here you go Nige. Hope its legible enough for you

[Image: img006.jpg]
Thank Steve for the info Nige
  Reply
#8
(04-06-2019, 08:56 AM)Hemikiller Wrote:
(04-06-2019, 07:01 AM)Pegleg Wrote: Here you go Nige. Hope its legible enough for you

Pegleg beat me to it...

Being a '73, you probably have a dual area vacuum modulator, which are not adjustable. You could swap it for an adjustable one to tweak your shift points up or down a couple MPH, but if yours are way off spec, you probably have junk in the governor, or more serious problems.

Yes it has the dual modulator is it ok to swap for an adjustable modulator and what would be the best colour . Nige
  Reply
#9
Looking at the charts, your trans seems to be operating within the ranges spec'd by Ford. You could replace the modulator with a single, but it appears yours might be adjustable. If it looks like the unit in the pic with the nipple along the axis of the modulator, then you can adjust it. You could also increase the length of the pin to increase shift mph and firmness.

https://www.ford-trucks.com/forums/97159...oding.html


  Reply
#10
(04-05-2019, 02:04 PM)Nige Wrote: 73 mach 1 2 barrel 351c with c6 auto transmission

Car goes into 3rd before 30 mph and do not change down until about 10 mph is this normal.

Nige

That sounds similar to how my c4 shifts, during NORMAL acceleration. Standing on it changes the shift points dramatically, although I do have a shift kit installed.

73 ragtop, 1999 Mustang Bright Atlantic Blue Paint, Phoenix Engine 302-335HP,  Edelbrock Carb & Performer manifold; c4 with 2000 stall and shiftkit; 3:55 auburn limited slip differential, Hedman shorties; Car Chemistry Exhaust

Classic Air; Tilt Steering Wheel; 1999 Chrysler Sebring bucket Seats ; power windows;
  Reply
Share Thread:  


Possibly Related Threads…
Thread Author Replies Views Last Post
  New fuel line after intake and carb change. klinton994 3 205 05-24-2019, 07:58 PM
Last Post: c9zx
  Car smoking after oil change mcampbell26915 21 763 05-01-2019, 09:12 AM
Last Post: c9zx
  distributor gear problems mycoses 14 2,860 10-28-2018, 10:15 AM
Last Post: tony-muscle
  distributor gear markc 7 452 10-19-2018, 10:46 PM
Last Post: markc
  71 Mach 1 C6 only starts in 2nd gear? dhvidston 9 456 10-01-2018, 11:43 PM
Last Post: rvrtrash
  Great article for serious gear heads c9zx 1 448 07-24-2018, 09:25 PM
Last Post: Don C
  Considering an Intake change 73pony 5 609 07-18-2018, 07:32 AM
Last Post: 73pony
  FMX Seal Change Mac 0 461 06-25-2018, 11:50 AM
Last Post: Mac



Users browsing this thread: 1 Guest(s)