• Mustang Forums
  • 1965 - 1973 Classic Mustangs -General/Talk-
  • Classic Mustang Specific Tech

please help with hard shifting tranny

  • Thread starter Thread starter mxmattd
  • Start date Start date Jan 19, 2007
M

mxmattd

New Member
Jun 3, 2004
73
0
0
Orange County, California
Jan 19, 2007
#1
  • Jan 19, 2007
  • #1
i bought my mustang a couple years ago looking to drive it on the weekends and fix the minor problems it had. one of these problems is a very hard 3-2 downshift in the c-4 tranny. I was told it was rebuilt about a year or two before i bought it, but the problem seems to be getting worse. sometimes when its very cold, it doesn't want to upshift from second to third, and when it does, it doesn't shift back down when i stop. any ideas what could be causing this? as always i pray for an easy (cheap) fix
 

rbohm

Founding Member
Apr 12, 2002
6,698
550
204
tucson,az
Jan 19, 2007
#2
  • Jan 19, 2007
  • #2
i would replace the modulator valve as that is usually the culprit. they are not expensive, probably $15 iirc. get the one with a single nipple. also set the adjustment screw about halfway out as an intial adjustment.
 
B

bnickel

Founding Member
Aug 21, 2002
5,640
3
77
lubbock, texas
Jan 19, 2007
#3
  • Jan 19, 2007
  • #3
i had a similar problem with mine and it was due to a bad governor, which resulted from the the front pump chewing itself to pieces. the modulator shouldn't have any effect on the downshift as it only controls upshifts.
 
M

mxmattd

New Member
Jun 3, 2004
73
0
0
Orange County, California
Jan 19, 2007
#4
  • Jan 19, 2007
  • #4
bnickel-

what parts had to be replaced in your case? did you have to have the tranny rebuilt?
 
T

TOM B

20+ Year Stangneter
Nov 15, 2002
872
1
16
Harrisburg Pa
Jan 19, 2007
#5
  • Jan 19, 2007
  • #5
I just posted this on another Question, before you take anything apart try
some LUCAS trany shift improover, This stuff works, I tryed the rest and found Lucas works as it says. OH yea, Maybe I should say that Im a mechanic now for 30 years.
I think I just gave my age away.
 
B

bnickel

Founding Member
Aug 21, 2002
5,640
3
77
lubbock, texas
Jan 19, 2007
#6
  • Jan 19, 2007
  • #6
mxmattd said:
bnickel-

what parts had to be replaced in your case? did you have to have the tranny rebuilt?
Click to expand...


in my case the trans did have to be rebuilt because when the pump started to self destruct it sent metal shaving all through the trans which is what made the governor hang up. it had other problems as well but mainly what you describe. it's actually quite amazing that it was still working at all . the pump had literally started to grind itself to bits and there were grooves at least 1/4" deep all over it, it was mess.
 
D

D.Hearne

New Member
Sep 29, 2000
11,730
6
0
south louisiana
Jan 19, 2007
#7
  • Jan 19, 2007
  • #7
Last C-4 I had, had the same problems. This was due to it sitting up and the seals drying out inside. It eventually quit pulling altogether. I too would try the Lucas stuff first before a rebuild. Their Transmission treatment saved me a rebuild on an E4OD. But then again the trans fix Lucas stuff frees up sticky parts, I don't recall it doing anything about bad seals. Cost you $10 though to find out. The stuff also worked great on the C-6 in my 68 Merc. Poured one bottle in it, drove around the block 4 times and it shifted almost like new.
 
You must log in or register to reply here.

Similar threads

K
Electrical 2000 GT Intermittent Engine Shutdown In Motion - DTC U1262
  • kenster1092
  • Apr 13, 2026
  • SN95 4.6L Mustang Tech
Replies
4
Views
166
SN95 4.6L Mustang Tech Apr 24, 2026
squeak93
T
2002 V6 3.8L Help Me
  • TheIncompetentMechanic
  • Apr 4, 2026
  • 1996 - 2004 SN95 Mustang -General/Talk-
  • 2 3
Replies
50
Views
720
1996 - 2004 SN95 Mustang -General/Talk- May 12, 2026
TheIncompetentMechanic
T
L
Help with 1986 GT 5 Speed Please
  • Lcasada1999
  • Mar 20, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
7
Views
231
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Jun 21, 2026
CAMTWO1070
Hard to start when engine is cold
  • 86_Capri
  • Mar 11, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 2
Replies
32
Views
869
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Jun 21, 2026
CAMTWO1070
K
TKX Transmission Shifting Problem
  • KWC156
  • Jun 23, 2025
  • Other Auto Tech
  • 2
Replies
21
Views
2K
Other Auto Tech Jun 13, 2026
427nostang
4
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1965 - 1973 Classic Mustangs -General/Talk-
  • Classic Mustang Specific Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?