Home » Public Forums » GMCnet » Switch pitch and "ID"ing a manny tranny
| Switch pitch and "ID"ing a manny tranny [message #287180] |
Sun, 13 September 2015 17:56  |
skip2
Messages: 544
Registered: September 2011
Location: Winter Haven,FL (center o...
Karma: 3
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Been going through some of the PO's old receipts and look like he went through 3 trannys way back in 2002.
Had it repaired twice then the final receipt just said "installed rebuilt transmision and allison converter." I'm curious how far back Manny went with rebuiding tranny's with his special mojo and is there any kind of marks from the ouside. And to add to the confusion I found receipts from Jim K for 3.55 gears in 2000. And even gets better with some notation in repair logs about switch pitch. I heard about the switch pitch setup but never really understood what it does or why or how it would be useful. Any comments on anything I've mentioned would be appreciated. Just a note, I've never had a moments problem with the tranny in the 4 years I've had it and it tows the towd or boat without a bit of argument. Hope I didn't just jinx myself. Skip Hartline
74 Canyon Lands, FiTech,
3.7 FD LSD, Manny Tranny,
Springfield Distributor,
2001 Chevy Tracker Ragtop Towd
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| Re: Switch pitch and "ID"ing a manny tranny [message #287199 is a reply to message #287180] |
Sun, 13 September 2015 20:45  |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
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skip2 wrote on Sun, 13 September 2015 15:56Been going through some of the PO's old receipts and look like he went through 3 trannys way back in 2002.
Had it repaired twice then the final receipt just said "installed rebuilt transmision and allison converter." I'm curious how far back Manny went with rebuiding tranny's with his special mojo and is there any kind of marks from the ouside. And to add to the confusion I found receipts from Jim K for 3.55 gears in 2000. And even gets better with some notation in repair logs about switch pitch. I heard about the switch pitch setup but never really understood what it does or why or how it would be useful. Any comments on anything I've mentioned would be appreciated. Just a note, I've never had a moments problem with the tranny in the 4 years I've had it and it tows the towd or boat without a bit of argument. Hope I didn't just jinx myself. Skip Hartline
Skip,
I have no idea about how long Manny has been doing transmissions. I would think a Switch Pitch would be his. You can identify a SP by looking under the coach on the riders side of the transmission, just ahead of the modulator there is a place for one or two wires to connect to the transmission. One wire, on a vertical blade is a regular. A second blade, above the first, but lateral is a SP.
The SP has a two "stall speed" torque converter. I did not know Allison made one, but I don't know a lot of things. Anyway, when no 12 Volts are on the wire to the top blade, the torque converter stall is abound 1700 RPMs. This means if you locked the wheels and floored it (I would not suggest doing this) the engine would only rev to 1700. (Stock converters in GMCs is more like 2200) When 12 volts is applied to the SP blade the fins on the converter switch and the stall becomes about 2600.
This means the converter sort of has a high and low gear range. The thing is this is not entirely true because the higher RPMS you go the more the converter is moving toward lock up. (It never does and always slips some.) So, in switch or out of switch, at 3000 RPMs there is very little difference.
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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| Re: Switch pitch and "ID"ing a manny tranny [message #287217 is a reply to message #287199] |
Mon, 14 September 2015 00:44 |
LarryInSanDiego
Messages: 336
Registered: September 2006
Karma: 0
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I wouldn't rely on a two wire connector always being a switch pitch. I had a '70's Cadillac with the connector you're describing on the TH400. IIRC, I found out by looking at a schematic that it was part of a spark retard circuit for emissions.
Larry Engelbrecht
San Diego, CA
'73 26' ex-Glacier
TZE063V100319 03/07/73
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| Re: [GMCnet] Switch pitch and "ID"ing a manny tranny [message #288455 is a reply to message #287180] |
Sat, 10 October 2015 06:52 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Skip,
Manny uses only stainless steel bolt on his rebuilds so all you need do is
look for shiny pan bolts.
I don't know how you'd tell a switch pitch other than by performance.
Having never driven one, I can't help with that.
Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI & EBL,
Manny Brakes & 1-Ton, etc., etc.
www.gmcwipersetc.com
On Sun, Sep 13, 2015 at 6:56 PM, Skip Hartline
wrote:
> Been going through some of the PO's old receipts and look like he went
> through 3 trannys way back in 2002.
> Had it repaired twice then the final receipt just said "installed rebuilt
> transmision and allison converter." I'm curious how far back Manny went with
> rebuiding tranny's with his special mojo and is there any kind of marks
> from the ouside. And to add to the confusion I found receipts from Jim K for
> 3.55 gears in 2000. And even gets better with some notation in repair logs
> about switch pitch. I heard about the switch pitch setup but never really
> understood what it does or why or how it would be useful. Any comments on
> anything I've mentioned would be appreciated. Just a note, I've never had a
> moments problem with the tranny in the 4 years I've had it and it tows the
> towd or boat without a bit of argument. Hope I didn't just jinx myself.
> Skip Hartline
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Switch pitch and "ID"ing a manny tranny [message #288483 is a reply to message #288455] |
Sat, 10 October 2015 18:00 |
 |
USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Ken et al,
If you remove the electrical connector forward of the modulator on the passenger side of the transmission it will have:
A) One blade if it is a "normal" TH-425
B) Two blades if it is a switch pitch TH-425
The information below is from the TH-425 Switch Pitch Transmission Manual (22mb) which can be downloaded here:
http://www.bdub.net/manuals/1967_Toronado_Switch_Pitch_Transmission.pdf
Page 7E-21 / Figure 7E-36 - Removing Connector shows two wires coming from the connector.
Page 7E-24 / Figure 7E-54 - Removing Electrical Connector shows two pins on the connector.
Page 7E-67 / Figure 7E-220 - Attaching Bolt Location shows two solenoids; Detent and Stator.
A "normal" TH-425 only has one solenoid (Detent) and one blade on the connector.
Page 7E-2 - General Description
The 12 volt electrical signal is used to operate the electrical detent and stator solenoids. The detent solenoid is activated by an
electrical switch in the throttle linkage. When the throttle is fully opened the switch in the throttle linkage is closed,
activating the detent solenoid and causing the transmission to downshift at speeds below approximately 70 mph.
The stator solenoid is also activated by an electrical switch in the throttle linkage. The stator is activated at small carburetor
openings to reduce creep, and at large carburetor openings and high speeds to increase engine output. The manual linkage is used to
select the desired
Regards,
Rob M.
The Pedantic Mechanic
-----Original Message-----
From: Ken Henderson
Skip,
Manny uses only stainless steel bolt on his rebuilds so all you need do is
look for shiny pan bolts.
I don't know how you'd tell a switch pitch other than by performance.
Having never driven one, I can't help with that.
Ken H.
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Switch pitch and "ID"ing a manny tranny [message #288492 is a reply to message #288483] |
Sat, 10 October 2015 20:49 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Rob,
I can "garauntee" you that the two-terminal connector is NOT proof-positive
of having a switch-pitch transmission. All it proves is that it has two
terminals. :-)
Ken H.
On Sat, Oct 10, 2015 at 7:00 PM, Robert Mueller
wrote:
> Ken et al,
>
> If you remove the electrical connector forward of the modulator on the
> passenger side of the transmission it will have:
>
> A) One blade if it is a "normal" TH-425
>
> B) Two blades if it is a switch pitch TH-425
>
> The information below is from the TH-425 Switch Pitch Transmission Manual
> (22mb) which can be downloaded here:
>
> http://www.bdub.net/manuals/1967_Toronado_Switch_Pitch_Transmission.pdf
>
> Page 7E-21 / Figure 7E-36 - Removing Connector shows two wires coming from
> the connector.
>
> Page 7E-24 / Figure 7E-54 - Removing Electrical Connector shows two pins
> on the connector.
>
> Page 7E-67 / Figure 7E-220 - Attaching Bolt Location shows two solenoids;
> Detent and Stator.
>
> A "normal" TH-425 only has one solenoid (Detent) and one blade on the
> connector.
>
> Page 7E-2 - General Description
>
> The 12 volt electrical signal is used to operate the electrical detent and
> stator solenoids. The detent solenoid is activated by an
> electrical switch in the throttle linkage. When the throttle is fully
> opened the switch in the throttle linkage is closed,
> activating the detent solenoid and causing the transmission to downshift
> at speeds below approximately 70 mph.
>
> The stator solenoid is also activated by an electrical switch in the
> throttle linkage. The stator is activated at small carburetor
> openings to reduce creep, and at large carburetor openings and high speeds
> to increase engine output. The manual linkage is used to
> select the desired
>
> Regards,
> Rob M.
> The Pedantic Mechanic
>
> -----Original Message-----
> From: Ken Henderson
>
> Skip,
>
> Manny uses only stainless steel bolt on his rebuilds so all you need do is
> look for shiny pan bolts.
>
> I don't know how you'd tell a switch pitch other than by performance.
> Having never driven one, I can't help with that.
>
> Ken H.
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Switch pitch and "ID"ing a manny tranny [message #288494 is a reply to message #288492] |
Sun, 11 October 2015 00:12 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Ken,
Jeez you're as pedantic as I am!
I agree with your statement. It is possible that the single terminal connector in a non-switch pitch transmission was replaced with
a two terminal connector from a switch pitch transmission; however, from where I sit that is a REMOTE possibility.
As you can see on page 7E-67 (Fig. 7E-220 Attaching Bolt Location) a single wire goes from the CASE ELECTRICAL CONNECTOR to the
detent solenoid and a single wire goes from the CASE ELECTRICAL CONNECTOR to the stator solenoid. Therefore both solenoids are
grounded internally somehow.
When 12 vdc is applied to either one of the solenoids they actuate.
How about this test?
If the plug on the CASE ELECTRICAL CONNECTOR is removed on the outside of a switch pitch transmission and one lead of an ohm meter
is connected to either on of the terminals and the second to the transmission housing the ohm meter should read continuity or
resistance through the solenoid coils. If the ohm meter reads continuity on one terminal only it is not a switch pitch transmission
OR it is a switch pitch transmission and
a) the wire to the solenoid coil is open
b) the solenoid coil is open
c) the solenoid is not grounded inside the transmission
Regards,
Rob M.
The Pedantic Mechanic
-----Original Message-----
From: Ken Henderson
Rob,
I can "garauntee" you that the two-terminal connector is NOT proof-positive of having a switch-pitch transmission. All it proves is
that it has two terminals. :-)
Ken H.
On Sat, Oct 10, 2015 at 7:00 PM, Robert Mueller
wrote:
> Ken et al,
>
> If you remove the electrical connector forward of the modulator on the
> passenger side of the transmission it will have:
>
> A) One blade if it is a "normal" TH-425
>
> B) Two blades if it is a switch pitch TH-425
>
> The information below is from the TH-425 Switch Pitch Transmission Manual
> (22mb) which can be downloaded here:
>
> http://www.bdub.net/manuals/1967_Toronado_Switch_Pitch_Transmission.pdf
> Page 7E-21 / Figure 7E-36 - Removing Connector shows two wires coming from
> the connector.
>
> Page 7E-24 / Figure 7E-54 - Removing Electrical Connector shows two pins
> on the connector.
>
> Page 7E-67 / Figure 7E-220 - Attaching Bolt Location shows two solenoids;
> Detent and Stator.
>
> A "normal" TH-425 only has one solenoid (Detent) and one blade on the
> connector.
>
> Page 7E-2 - General Description
>
> The 12 volt electrical signal is used to operate the electrical detent and
> stator solenoids. The detent solenoid is activated by an
> electrical switch in the throttle linkage. When the throttle is fully
> opened the switch in the throttle linkage is closed,
> activating the detent solenoid and causing the transmission to downshift
> at speeds below approximately 70 mph.
>
> The stator solenoid is also activated by an electrical switch in the
> throttle linkage. The stator is activated at small carburetor
> openings to reduce creep, and at large carburetor openings and high speeds
> to increase engine output. The manual linkage is used to
> select the desired
>
> Regards,
> Rob M.
> The Pedantic Mechanic
>
> -----Original Message-----
> From: Ken Henderson
>
> Skip,
>
> Manny uses only stainless steel bolt on his rebuilds so all you need do is
> look for shiny pan bolts.
>
> I don't know how you'd tell a switch pitch other than by performance.
> Having never driven one, I can't help with that.
>
> Ken H.
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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Unsubscribe or Change List Options:
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Switch pitch and "ID"ing a manny tranny [message #288530 is a reply to message #288455] |
Sun, 11 October 2015 21:47 |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
|
Senior Member |
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Ken Henderson wrote on Sat, 10 October 2015 04:52Skip,
I don't know how you'd tell a switch pitch other than by performance.
Having never driven one, I can't help with that.
Ken H.
Americus, GA
The driving test is interesting. This is what I call the "Manny Test". Upon install he had me start the engine, put the coach in drive. When I let the brake off it started to crawl with some enthusiasm.(This is at 650-700 idle. It will crawl to 3 or 5 mph easily on level ground.) Manny had me stop and put it in switch. When I let the brake off the coach hardly moved. I flipped it out of switch and it started to move out again.
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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