The Ford Torino Page Homepage
Forum Home Forum Home > Powertrain Specific Forum > Transmissions
  New Posts New Posts RSS Feed - C6 transmission thump into 1st gear
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

C6 transmission thump into 1st gear

 Post Reply Post Reply
Author
Message
Iain View Drop Down
Member
Member


Joined: 21-March-2020
Location: England
Status: Offline
Points: 61
Post Options Post Options   Thanks (0) Thanks(0)   Quote Iain Quote  Post ReplyReply Direct Link To This Post Topic: C6 transmission thump into 1st gear
    Posted: 10-September-2020 at 11:21PM
Hi all,
 
Had the car tuned up, carb sorted on the rolling road etc, so obviously theres something else to look into now!
 
When downshifting, the C6 thuds into 1st gear from 3rd, but shifts smoothly down from 2nd gear into 1st. Upshifts are all fine, reverse is fine too. Never noticed it previously, but now I do, and hope it isn't anything too horrendous to sort out.
 
Fluid is red and smells fine (a bit sweet according to my nose), it is the older fluid type (F), which I have checked the level of and topped up with around 500ml (a pint for you lot!Smile) as it read a bit low. It has a dipstick that has been welded back together(!) and is a pain to get in the tube due to the tube curves and coolant hoses(the weld is not an issue as it is quite close to the top).
Have checked the level when hot and in park, but not convinced of the reading.
 
Would low and/or high fluid possibly cause this? And what other possibilities are there?
 
 
Many thanks,
 
Iain.
 
Back to Top
Big Bird View Drop Down
Senior Member
Senior Member
Avatar

Joined: 25-August-2013
Location: New York
Status: Offline
Points: 4194
Post Options Post Options   Thanks (0) Thanks(0)   Quote Big Bird Quote  Post ReplyReply Direct Link To This Post Posted: 11-September-2020 at 11:53AM
High fluid really takes a lot to be noticeable.
Low fluid usually slips and engages late.
"What we do in full frontal view, is more honest than your cleaned-up mind."
Randy
1979 T-Bird
2005 F-150 STX RCSB 4.6, 3.55 LSD
How the Heck does a REGULAR CAB SHORTBED weigh over 5200 pounds?
Back to Top
Rockatansky View Drop Down
Senior Member
Senior Member


Joined: 30-July-2010
Location: On The Road
Status: Offline
Points: 6059
Post Options Post Options   Thanks (0) Thanks(0)   Quote Rockatansky Quote  Post ReplyReply Direct Link To This Post Posted: 11-September-2020 at 4:29PM
manually downshifting from 3rd to 1st?

is this with a manual valve body or is it still an automatic transmission?

my builder warned against manually downshifting on any kind of a regular basis, it's hard on the guts!

the clunk could be a sign that there's a planet set in the future for the C6? maybe Don 72 RS 351 can elaborate on the process that goes on internally to make the downshifts from each range to the next happen, my builder told me causing the band to apply to stop the drum is pretty tough on the giblets
72 GT Ute
   
Back to Top
Iain View Drop Down
Member
Member


Joined: 21-March-2020
Location: England
Status: Offline
Points: 61
Post Options Post Options   Thanks (0) Thanks(0)   Quote Iain Quote  Post ReplyReply Direct Link To This Post Posted: 11-September-2020 at 8:45PM
Still fully auto, shifting itself in all cases.
Shifts fine in all other ways, just the 3 to 1 when stopping. If I slow down gradually, and it goes to 2nd, then 1st, it's smooth. Dread to think of a rebuild cost over here when you can get recon c6 units in the US for not much over 2k dollars. 

Back to Top
Rockatansky View Drop Down
Senior Member
Senior Member


Joined: 30-July-2010
Location: On The Road
Status: Offline
Points: 6059
Post Options Post Options   Thanks (0) Thanks(0)   Quote Rockatansky Quote  Post ReplyReply Direct Link To This Post Posted: 11-September-2020 at 9:40PM
are you sure it's not the mount or U-joints?

not too long ago a 'bench job' for pretty much any rear wheel drive was about $500

72 GT Ute
   
Back to Top
Iain View Drop Down
Member
Member


Joined: 21-March-2020
Location: England
Status: Offline
Points: 61
Post Options Post Options   Thanks (0) Thanks(0)   Quote Iain Quote  Post ReplyReply Direct Link To This Post Posted: 11-September-2020 at 9:46PM
Will check it out and try to wobble stuff under the car.
Gearboxes are stupid over here, cars get scrapped as it's not worth the money to exchange or rebuild. Not in this case though! 

Back to Top
Iain View Drop Down
Member
Member


Joined: 21-March-2020
Location: England
Status: Offline
Points: 61
Post Options Post Options   Thanks (0) Thanks(0)   Quote Iain Quote  Post ReplyReply Direct Link To This Post Posted: 11-September-2020 at 9:47PM
Tick over is a little low too, not that I should affect this issue.  
Back to Top
72FordGTS View Drop Down
Admin Group
Admin Group
Avatar
GTS.org Admin

Joined: 06-September-2005
Location: Ontario, Canada
Status: Offline
Points: 5802
Post Options Post Options   Thanks (0) Thanks(0)   Quote 72FordGTS Quote  Post ReplyReply Direct Link To This Post Posted: 12-September-2020 at 2:29AM
I agree with Rock, make sure you check the remainder of the driveline for slop.  Hows the differential for slop?

There is also the Ford Transmission forum if we can't figure it out:

Vince

1972 Ford GTS Sportsroof - Survivor, One Family car

GTS.org Admin
Back to Top
Big Bird View Drop Down
Senior Member
Senior Member
Avatar

Joined: 25-August-2013
Location: New York
Status: Offline
Points: 4194
Post Options Post Options   Thanks (0) Thanks(0)   Quote Big Bird Quote  Post ReplyReply Direct Link To This Post Posted: 12-September-2020 at 2:35AM
Do look at your engine mounts as well. Left side in particular.
Transmission mount, U-joints, and yoke bushing.
"What we do in full frontal view, is more honest than your cleaned-up mind."
Randy
1979 T-Bird
2005 F-150 STX RCSB 4.6, 3.55 LSD
How the Heck does a REGULAR CAB SHORTBED weigh over 5200 pounds?
Back to Top
72 RS 351 View Drop Down
Senior Member
Senior Member
Avatar

Joined: 04-September-2014
Location: Knoxville TN
Status: Offline
Points: 2765
Post Options Post Options   Thanks (0) Thanks(0)   Quote 72 RS 351 Quote  Post ReplyReply Direct Link To This Post Posted: 12-September-2020 at 9:34AM
Ditto, be sure that nothing else external might be causing the symptom. If you decide it's the trans, I'd check into a valve body kit before thinking of something worse or more expensive to do.

A VB kit is virtually always a great improvement to over all driveability. I'm not familiar with the C6 at all, the only automatics I've worked with are the four speeds, AOD/AODE/4R70W. There are lots of VB components and kits for those.

The C6 is a strong trans and Ford worked it out ages ago. But I'm sure you can find suggestions for what can be upgraded just through the pan. I will need the same advice myself with my new 73, the C6 is supposed to be newly rebuilt. But I like to do a VB kit as it makes shifting quicker, and that alone makes it last longer.
Don
73 Ranchero "Sport 72 front end", floor shift/console, planning EFI 7000+ rpm 351-4V &4R70W
73 Ranchero GT 351C-4V &4R70W for sale later.
92 Lincoln Mark VII SE GTC, OBDII 347/4R70W
Back to Top
californiajohnny View Drop Down
Moderator Group
Moderator Group
Avatar

Joined: 05-October-2013
Location: winlock, wa
Status: Offline
Points: 14606
Post Options Post Options   Thanks (0) Thanks(0)   Quote californiajohnny Quote  Post ReplyReply Direct Link To This Post Posted: 12-September-2020 at 6:03PM
i did a shift kit in a C6 years ago for a buddy it was a bit more involved than say for a TH350 or TH400 but nothing too difficult Wink
JOHN
74 GRAN TORINO S&H CLONE
74 VETTE CUSTOM
90 S10 BLAZER 4X4 LIFTED
77 CELICA CUSTOM
75 V8 MONZA SUPERCHARGED
79 COURIER VERT. SLAMMED
75 VEGA V6 5 SPD
70 CHEV C10 P/U
68 MUSTANG FB CONVERSION
Back to Top
aquartlow View Drop Down
Senior Member
Senior Member


Joined: 19-December-2011
Location: Summerfield, Fl
Status: Offline
Points: 2270
Post Options Post Options   Thanks (0) Thanks(0)   Quote aquartlow Quote  Post ReplyReply Direct Link To This Post Posted: 13-September-2020 at 1:19AM
The "thump" could be a few things. What is your idle rpm(too high and the trans can make the downshift  feel a bit more abrupt). Governor may need cleaning and possibly a valve body valve and/or spring issue. A C6 really needs a shift kit of some-sort installed, I have used a B&M Transpak in my C6's with good results, a Transgo kit is said to be the best out there for a C6. Here is a link to a Ford transmission forum, great guys there.    https://www.tapatalk.com/groups/fordtransmissionforum/index.php
 Hope this helps.
www.supermotors.net/22468
Yeah, It's a Hybrid...It burns gas and tires.

No matter how good she looks, somebody, somewhere, is tired of her sh*t.

Beauty is skin deep, ugliness goes clear to the bone.
Back to Top
72 RS 351 View Drop Down
Senior Member
Senior Member
Avatar

Joined: 04-September-2014
Location: Knoxville TN
Status: Offline
Points: 2765
Post Options Post Options   Thanks (0) Thanks(0)   Quote 72 RS 351 Quote  Post ReplyReply Direct Link To This Post Posted: 13-September-2020 at 3:25AM
TransGo was my favorite for the AOD VB kits. They were much more involved(more parts and things to do), the instructions were excellent. Other brands were few in the 80's when I began learning the AOD and VB kits. The other brands were very sparse with parts or instructions, they required very few changes, parts or holes drilled, minimal instructions. The results were poor also, harsher shifting at low throttle settings and clunky shifting overall(down shifting included).

Things have changed over decades, for sure, and I don't know what other brands have done since about 2000. I liked the driveability improvements a bunch with TransGo VB kits, everything was better not counting the WOT shifts. The kits allowed adjustments(choice) of the level of WOT shifting.

I would tend to try the TransGo kit if nobody else suggests something amazing from another brand.
Don
73 Ranchero "Sport 72 front end", floor shift/console, planning EFI 7000+ rpm 351-4V &4R70W
73 Ranchero GT 351C-4V &4R70W for sale later.
92 Lincoln Mark VII SE GTC, OBDII 347/4R70W
Back to Top
Iain View Drop Down
Member
Member


Joined: 21-March-2020
Location: England
Status: Offline
Points: 61
Post Options Post Options   Thanks (0) Thanks(0)   Quote Iain Quote  Post ReplyReply Direct Link To This Post Posted: 13-September-2020 at 9:40AM
Thanks for the replies guys.

It didn't do the thud today on the way home, but I did some good 'zooming' around this morning! Quick acceleration and harder than usual braking. Will check under the car later this week for anything odd. 

I think the diff is due for refurb too, as I left a '1' instead of an '11'!
Back to Top
72 RS 351 View Drop Down
Senior Member
Senior Member
Avatar

Joined: 04-September-2014
Location: Knoxville TN
Status: Offline
Points: 2765
Post Options Post Options   Thanks (0) Thanks(0)   Quote 72 RS 351 Quote  Post ReplyReply Direct Link To This Post Posted: 13-September-2020 at 12:08PM
That's something we don't often do enough, drive it hard occasionally. That helps to work out the bugs, find them, and kill them.

I haven't worked on a 9" in decades, I do remember how heavy the chunk was though. I've got a 4.11 LS in my older truck, and a 3.70 in my new one. I'll have to swap them assuming I sell the old truck and rear with it. The 4.11 is too much for a typical C6 truck unless the owner really needs that. I did it to use with an AOD and a mild 351C-2V. Things change, now I think a 3.50 is about the right gear with an over drive.
Don
73 Ranchero "Sport 72 front end", floor shift/console, planning EFI 7000+ rpm 351-4V &4R70W
73 Ranchero GT 351C-4V &4R70W for sale later.
92 Lincoln Mark VII SE GTC, OBDII 347/4R70W
Back to Top
Iain View Drop Down
Member
Member


Joined: 21-March-2020
Location: England
Status: Offline
Points: 61
Post Options Post Options   Thanks (0) Thanks(0)   Quote Iain Quote  Post ReplyReply Direct Link To This Post Posted: 23-September-2020 at 8:35AM
Had a good root around, didn't find anything obvious, aside from one starter motor bolt was half out!
Several small leaks here and there, but nothing 'clunky!' 
The search continues....... 
Back to Top
Rockatansky View Drop Down
Senior Member
Senior Member


Joined: 30-July-2010
Location: On The Road
Status: Offline
Points: 6059
Post Options Post Options   Thanks (0) Thanks(0)   Quote Rockatansky Quote  Post ReplyReply Direct Link To This Post Posted: 26-September-2020 at 4:06PM
i just happened across a good teardown & inspect vid




72 GT Ute
   
Back to Top
Iain View Drop Down
Member
Member


Joined: 21-March-2020
Location: England
Status: Offline
Points: 61
Post Options Post Options   Thanks (0) Thanks(0)   Quote Iain Quote  Post ReplyReply Direct Link To This Post Posted: 19-October-2020 at 5:11AM
Seem to have stopped the thump into 1st gear. I upped the tick over and it has gone. Would this mean the vacuum to the box was too high, and it has lowered slightly as the flaps are a touch more open?
I know about the modulator, but have not looked at it to see whether it is adjustable or not.
Tickover was too low anyway, but I don't know how low as my tach works when it feels like it! Winter job that one! 
Was getting concerned in case it was box out time. Not yet it seems! 
Back to Top
 Post Reply Post Reply

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.06
Copyright ©2001-2023 Web Wiz Ltd.

This page was generated in 0.125 seconds.