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J-Mod Question

  • Thread starter Thread starter Dusstbuster
  • Start date Start date Apr 5, 2007

Dusstbuster

I love meat more than anything! I just have a spec
May 31, 2004
1,462
33
64
Moorhead, Minnesota
Apr 5, 2007
#1
  • Apr 5, 2007
  • #1
So I've been reading up on the J-mod and remember hearing awhile back that the reason you're supposed to turn OD off in a car while racing is because you can destroy the OD gear if it shifts at WOT due to some slippage. Will the J-Mod reduce/remove this issue as far as slipping or misshifting into OD and allow you to keep OD on? I know it firms up the shifts and reduces tranny wear so I'm assuming it helps the OD shift as well?
 
T

TGJ

New Member
Mar 30, 2005
1,049
4
0
Apr 5, 2007
#2
  • Apr 5, 2007
  • #2
Dusstbuster said:
So I've been reading up on the J-mod and remember hearing awhile back that the reason you're supposed to turn OD off in a car while racing is because you can destroy the OD gear if it shifts at WOT due to some slippage. Will the J-Mod reduce/remove this issue as far as slipping or misshifting into OD and allow you to keep OD on? I know it firms up the shifts and reduces tranny wear so I'm assuming it helps the OD shift as well?
Click to expand...

You have brought up the biggest weakness of the 4R70W. The JMod helps shifts into overdrive but it does not correct the problem of shifting into OD at WOT. There is no fix currently that will allow a WOT shift in OD, not even a fully built 4R70W, you will break something and not neccessarily OD. I have seen input shafts break as well.
 

Dusstbuster

I love meat more than anything! I just have a spec
May 31, 2004
1,462
33
64
Moorhead, Minnesota
Apr 5, 2007
#3
  • Apr 5, 2007
  • #3
Well that's depressing
 

merc123

Active Member
Jan 27, 2003
420
2
39
North GA
Apr 5, 2007
#4
  • Apr 5, 2007
  • #4
I don't know much about the stang's auto tranny, but you're seriously going fast enough to hit OD at WOT when racing?
 

Dusstbuster

I love meat more than anything! I just have a spec
May 31, 2004
1,462
33
64
Moorhead, Minnesota
Apr 5, 2007
#5
  • Apr 5, 2007
  • #5
merc123 said:
I don't know much about the stang's auto tranny, but you're seriously going fast enough to hit OD at WOT when racing?
Click to expand...

Easily...the car goes through the first 3 gears pretty damn quick with the 3.73's
 
K

Kilgore Trout

Fried or Broiled ?
10 Year Member
Mar 30, 2005
4,749
95
134
Apr 5, 2007
#6
  • Apr 5, 2007
  • #6
Overdive is simply not designed to take a lot of torque. The j-mod will not redesign the trans to make it something it isn't
 

Dusstbuster

I love meat more than anything! I just have a spec
May 31, 2004
1,462
33
64
Moorhead, Minnesota
Apr 5, 2007
#7
  • Apr 5, 2007
  • #7
Kilgore Trout said:
Overdive is simply not designed to take a lot of torque. The j-mod will not redesign the trans to make it something it isn't
Click to expand...

I know I was just hoping that the firmer shifts would help reduce the stress of the shift on OD. Whats even worse is that if it comes to that point in the RPM range and you have OD off, the tranny overrides the "off" and kicks it into OD anyways.
 

propellerhead

New Member
Apr 13, 2004
1,541
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0
"but what's with the but shots?"
Apr 5, 2007
#8
  • Apr 5, 2007
  • #8
I have not seen any credible data on this idea of breaking something by shifting into 4th at WOT. I still think it's a myth.
 

CobraRed_96_GT

Active Member
May 20, 2006
1,421
4
39
UCSD/La Jolla
Apr 5, 2007
#9
  • Apr 5, 2007
  • #9
this is one of many reasons i have a new OD servo gear and hardened input and intermediate shafts from the rebuild. The OD gear is funny, i have 3.73's and w/ a 98-100mph trap on the 1/4 it really needs to shift
 
T

TGJ

New Member
Mar 30, 2005
1,049
4
0
Apr 5, 2007
#10
  • Apr 5, 2007
  • #10
propellerhead said:
I have not seen any credible data on this idea of breaking something by shifting into 4th at WOT. I still think it's a myth.
Click to expand...

http://forums.tccoa.com/showthread.php?t=67549

Still a myth?

Dusstbuster said:
I know I was just hoping that the firmer shifts would help reduce the stress of the shift on OD. Whats even worse is that if it comes to that point in the RPM range and you have OD off, the tranny overrides the "off" and kicks it into OD anyways.
Click to expand...

Nothing that a tune can't fix.
 

propellerhead

New Member
Apr 13, 2004
1,541
0
0
"but what's with the but shots?"
Apr 5, 2007
#11
  • Apr 5, 2007
  • #11
TGJ said:
http://forums.tccoa.com/showthread.php?t=67549

Still a myth?
Click to expand...
Wow! That is the first time I've seen that. Everything else for the past few years has been "I heard..." or "They say..."

Thanks.
 

CobraRed_96_GT

Active Member
May 20, 2006
1,421
4
39
UCSD/La Jolla
Apr 5, 2007
#12
  • Apr 5, 2007
  • #12
wow, yeah - od off at wot FTW. You shouldn't need to use OD for a WOT 1/4 mile n e wayz
 

03ghoststang

Well-Known Member
Jul 16, 2005
1,930
1
57
Los Angeles, California
Apr 5, 2007
#13
  • Apr 5, 2007
  • #13
wow even though i have heard of not doing that.........i am still not going to be doing that O/D shift at WOT = FTL


and as far as the J-mod goes it's just modifying the valve body of the trans, unless you open the trans up and swap stuff out that is all your doing
 
J

justinschmidt1

Member
Jun 15, 2005
349
0
16
Apr 5, 2007
#14
  • Apr 5, 2007
  • #14
my auto over rides and shifts into o/d at like 5k for some reason...its pretty stupid.
 

Dusstbuster

I love meat more than anything! I just have a spec
May 31, 2004
1,462
33
64
Moorhead, Minnesota
Apr 5, 2007
#15
  • Apr 5, 2007
  • #15
justinschmidt1 said:
my auto over rides and shifts into o/d at like 5k for some reason...its pretty stupid.
Click to expand...

Yeah same here...
 
S

san~man

O-G
Founding Member
Nov 29, 1999
8,546
3
78
A little grass shack on a big lava rock
Apr 6, 2007
#16
  • Apr 6, 2007
  • #16
Mine don't....like TGJ said, it's in the programming.
 

Dusstbuster

I love meat more than anything! I just have a spec
May 31, 2004
1,462
33
64
Moorhead, Minnesota
Apr 6, 2007
#17
  • Apr 6, 2007
  • #17
Will a Predator AND Xcal fix it? The guy I'm planning on getting dynotuned with uses a Predator.
 
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