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can an auto trans shift "too hard", causing damage?
#1579739
02/16/14 02:07 PM
02/16/14 02:07 PM
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Joined: Aug 2003
Posts: 12,589
Sacramento, CA
cal_gecko
OP
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OP
I Live Here
Joined: Aug 2003
Posts: 12,589
Sacramento, CA
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Just curious.. with the stuff I've got in my 904, it shifts REALLY hard.. almost violently ..
Griner reverse manual VB with low band apply
Red clutches with Kolene Steels
Low 1st gear
Kevlar bands
mild torque converter (I think around 2800 rpm)
The engine is a mild 360 ..
When it shifts, it knocks you back in your seat.. depending on RPMs and throttle, it has no problem breaking the tires loose going from 1-2 and will sometimes do it going from 2-3 ...
So my question is, .. "is there any risk of causing damage to other components of the drivetrain by having a shift that is this 'hard'?"
Rear end is recently completely rebuilt .. new Eaton True-Track, new ring/pinion, bearings, etc..
What would any potential 'weak point' be that I should consider beefing up for the way this thing shifts?
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Re: can an auto trans shift "too hard", causing damage?
[Re: cal_gecko]
#1579740
02/16/14 03:39 PM
02/16/14 03:39 PM
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Joined: Dec 2003
Posts: 22,696
Bitopia
jcc
If you can't dazzle em with diamonds..
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If you can't dazzle em with diamonds..
Joined: Dec 2003
Posts: 22,696
Bitopia
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Weak point my guess in your case would be DS/U joints, but the hard shifting in a street car would get old fast for me.
Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
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Re: can an auto trans shift "too hard", causing damage?
[Re: Cab_Burge]
#1579743
02/16/14 05:45 PM
02/16/14 05:45 PM
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Joined: Aug 2003
Posts: 12,589
Sacramento, CA
cal_gecko
OP
I Live Here
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OP
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Posts: 12,589
Sacramento, CA
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Quote:
Harsh shifts like your having are usually caused by two gears being engaged, overap, at the same time   Check your shifter adjustment   I make sure the button on the shifter cable will slide easily into the shifter arm in nuetral, 1st, 2nd and 3rd gear with no visible movement of the shifter arm or button  If either moves adjust the parts until they don't
I recently double checked my adjustments and the trans doesn't shift any different, so I'm guessing they're where they should have been.. but I'll double check the cable going to the shift linkage to ensure that when it goes into gear, it's not close to another gear.. I'm using a B&M Quicksilver shifter, if that matters.. I doubt it though.
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Re: can an auto trans shift "too hard", causing damage?
[Re: 340SHORTY]
#1579745
02/16/14 06:11 PM
02/16/14 06:11 PM
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Joined: Aug 2003
Posts: 12,589
Sacramento, CA
cal_gecko
OP
I Live Here
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OP
I Live Here
Joined: Aug 2003
Posts: 12,589
Sacramento, CA
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Quote:
race tranny in a street car.. 
That's what I get for asking John Cope for transmission advice, LOL!!
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Re: can an auto trans shift "too hard", causing damage?
[Re: cal_gecko]
#1579746
02/16/14 07:45 PM
02/16/14 07:45 PM
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Joined: Feb 2004
Posts: 1,012
indiana
mcmopars
super stock
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super stock
Joined: Feb 2004
Posts: 1,012
indiana
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Quote:
Just curious.. with the stuff I've got in my 904, it shifts REALLY hard.. almost violently ..
Griner reverse manual VB with low band apply
Red clutches with Kolene Steels
Low 1st gear
Kevlar bands
mild torque converter (I think around 2800 rpm)
The engine is a mild 360 ..
When it shifts, it knocks you back in your seat.. depending on RPMs and throttle, it has no problem breaking the tires loose going from 1-2 and will sometimes do it going from 2-3 ...
So my question is, .. "is there any risk of causing damage to other components of the drivetrain by having a shift that is this 'hard'?"
Rear end is recently completely rebuilt .. new Eaton True-Track, new ring/pinion, bearings, etc..
What would any potential 'weak point' be that I should consider beefing up for the way this thing shifts?
awsome 360 theat will bust em loose on 2-3 shift.my cope built mvb trans shifts very hard at cruising,to the point i dont like it ,never broke anything yet,full throttle is very firm.its street driven,if i had to do it again i would have him build a auto shifting trans.just make sure you have the good u-joints,which im sure you do.
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Re: can an auto trans shift "too hard", causing damage?
[Re: cal_gecko]
#1579747
02/16/14 08:25 PM
02/16/14 08:25 PM
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Joined: Jan 2003
Posts: 25,877
Rio Linda, CA
John_Kunkel
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 25,877
Rio Linda, CA
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RMVB's run the line pressure wide open all the time, this results in WOT shifts even at low speeds.
The lighter the car, the lower the axle ratio and the tighter the converter, the more you will feel it in the "buttmeter"....and, yes, it's hard on parts.
The INTERNET, the MISinformation superhighway
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Re: can an auto trans shift "too hard", causing damage?
[Re: John_Kunkel]
#1579748
02/16/14 08:54 PM
02/16/14 08:54 PM
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Joined: Aug 2003
Posts: 12,589
Sacramento, CA
cal_gecko
OP
I Live Here
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OP
I Live Here
Joined: Aug 2003
Posts: 12,589
Sacramento, CA
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Quote:
RMVB's run the line pressure wide open all the time, this results in WOT shifts even at low speeds.
The lighter the car, the lower the axle ratio and the tighter the converter, the more you will feel it in the "buttmeter"....and, yes, it's hard on parts.
So, being that the Dart is not a super-heavy car, I have 3.55 gears, and a moderate torque converter.. those are some of the reasons it's so noticeable.. makes sense!
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Re: can an auto trans shift "too hard", causing damage?
[Re: 340SHORTY]
#1579751
02/18/14 10:31 AM
02/18/14 10:31 AM
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Joined: Aug 2012
Posts: 1,574
Lakeland FL
floridian
pro stock
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pro stock
Joined: Aug 2012
Posts: 1,574
Lakeland FL
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Quote:
race tranny in a street car..
I had a lowered 2WD stepside chevy with a 454/ turbo 400 that shifted like that.. Kinda fun but grew old fast... or maybe I just got old
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Re: can an auto trans shift "too hard", causing damage?
[Re: Cab_Burge]
#1579752
02/18/14 10:45 AM
02/18/14 10:45 AM
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Joined: Jun 2013
Posts: 16
Orlando, FL
98 SNAKE EATER
member
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member
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Posts: 16
Orlando, FL
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Quote:
Harsh shifts like your having are usually caused by two gears being engaged, overap, at the same time Check your shifter adjustment I make sure the button on the shifter cable will slide easily into the shifter arm in nuetral, 1st, 2nd and 3rd gear with no visible movement of the shifter arm or button If either moves adjust the parts until they don't
Won't make a difference in his case running a MVB
There's full line pressure for each shift, so it will shift hard regardless.
My 69 RR with a Cheetah RMVB shifts is the same way and breaks the tires loose very easily in any gear, so I usually up shift at a low RPM and just let the torque of the motor take care of things while cruising
Big soft sticky tires makes a huge difference though.
https://www.youtube.com/watch?v=rT5f2z7PTQc
It's almost buttery smooth when I run my MT Sportsman Pros
As for damage, U-Joints and seat backs come to mind 
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Re: can an auto trans shift "too hard", causing damage?
[Re: cal_gecko]
#1579753
02/18/14 11:44 AM
02/18/14 11:44 AM
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Joined: Jan 2003
Posts: 1,761
Windsor, ON, Canada
Diplomat360
top fuel
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top fuel
Joined: Jan 2003
Posts: 1,761
Windsor, ON, Canada
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I have a home built 727 here, the line pressure is adjusted to the MAX, pretty much too high, no doubt about it...the result is nearly what you describe, although I have often wondered if I get a slight bind between the 1st and 2nd gear because the shift is extremely harsh. 2nd to 3rd is softer...
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Re: can an auto trans shift "too hard", causing damage?
[Re: bonefish]
#1579755
02/18/14 02:49 PM
02/18/14 02:49 PM
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Joined: Jan 2003
Posts: 20,185
Park Forest, IL
slantzilla
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 20,185
Park Forest, IL
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It's easy to tell a hard shift from overlap. If you have overlap the car will drop the nose on the shift, a clean shift will keep it up. You can have overlap no matter what valve body you have.
"Everybody funny, now you funny too."
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Re: can an auto trans shift "too hard", causing damage?
[Re: Diplomat360]
#1579756
02/18/14 06:30 PM
02/18/14 06:30 PM
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Joined: Jan 2003
Posts: 75,047
U.S.S.A.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,047
U.S.S.A.
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Quote:
I have a home built 727 here, the line pressure is adjusted to the MAX, pretty much too high, no doubt about it...the result is nearly what you describe, although I have often wondered if I get a slight bind between the 1st and 2nd gear because the shift is extremely harsh. 2nd to 3rd is softer...
1st is the rear clutch engaged, it is engaged in ALL forward gears.
There is no way to have a BIND between 1st and second because all that is happening on the 1-2 shift is the front band is stopping the front drum from spinning...
unless you have a manual shift only valve body that has low band apply and the front band is stopping the front drum completely before the rear band releases ...
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Re: can an auto trans shift "too hard", causing damage?
[Re: JohnRR]
#1579757
02/18/14 06:45 PM
02/18/14 06:45 PM
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Joined: Jan 2003
Posts: 1,761
Windsor, ON, Canada
Diplomat360
top fuel
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top fuel
Joined: Jan 2003
Posts: 1,761
Windsor, ON, Canada
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Quote:
1st is the rear clutch engaged, it is engaged in ALL forward gears.
There is no way to have a BIND between 1st and second because all that is happening on the 1-2 shift is the front band is stopping the front drum from spinning...
unless you have a manual shift only valve body that has low band apply and the front band is stopping the front drum completely before the rear band releases ...
Ahh...very good information...well, this is a regular automatic valve body, the trans has been rebuilt with a SMR rebuild kit, fitted with a shift-kit, your typical 'shift improver' stuff and a few parts/add-ons that were suggested to me at that time like the 5.0 lever, accumulator blocker rod (keep in mind, this is a good 15 yrs ago...at least...). The car only has 1k miles since I finally got that thing on the road last year...LOL!
Specifically, the MP P4349469 kit (727 Accumulator and Piston Blocker Rod kit) states the following (which is where I got my MAX line pressure setup from):
=== START ===
Step3: Adjust line pressure to maximum with Allen head adjustment screw. Rotate counterclockwise to compress the spring until almost all available threads are used. Allow enough threads to completely egage adjustment bracket.
=== STOP ===
Other then the harsh but very quick gear shift (which I do not mind, even though it's jolting) I am happy with the trans. The 2nd to 3rd gear shift is much softer though...I think this is something that can be tuned though...need to do a little more research/reading.
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