what the heck is this? 3 speed overdrive? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

joe231 · 04-23-2008, 05:01 AM

anyone heard of these???
linky

kevindtimm · 04-23-2008, 05:23 AM

Yes, they are EXTREMELY cool! I used to have one, but the rebuild cost was too much for me (previous owner not too forthcoming about condition)

I would love to get another one, and know a guy locally who hoards them but a T5 is easier/less expensive to repair. If I had to choose? T85N w/OD (this item)

joe231 · 04-23-2008, 05:27 AM

i had no idea, what is the electrical stuff on it? is it a electric over drive. 3 speed plus over drive, or is 3rd gear the over drive?

Fred T · 04-23-2008, 06:25 AM

3rd gear plus OD. Electric switch for shifting in and out. Shifting was similar to a 2 speed rear on a 2 ton, it would shift after you switched it in and let up off the gas.

joe231 · 04-23-2008, 06:33 AM

wow, that is cool
thanks
the more i hear, the more convinced this tranny is what was in our '66 before my father in law swapped in a 283 and granny 4 speed, wish I knew what he did with the tranny

greg64 · 04-23-2008, 07:03 AM

So basically, are we dealing with a 2 speed in the extension housing? Never seen one of these animals....

kevindtimm · 04-23-2008, 04:35 PM

3 speed tranny, 2 speeds (1:1 and .70:1).

3000 RPM @ 65mph or
2100 RPM @ 65mph

SWEET!

Rogue 64 · 04-23-2008, 05:10 PM

I have seen Sag 4-speeds with those OD's adapted.
I thought about doing that, but I'm afraid the 327 would twist it all up.

rickf · 04-23-2008, 09:01 PM

At one time I was looking for one of these, they are hard to find. I found a lot of info on the net, though, e.g.
http://www.jalopyjournal.com/forum/s...d.php?t=249066

One of the things I came across (don't know where it is now) said these overdrives free-wheel when coasting forward. So, e.g. cruising on the freeweay on long downhill you may as well be in neutral, no engine braking. I don't know if that applied to all or just certain models, there are apparantly couple different actual overdrives units used.

kevindtimm · 04-23-2008, 10:17 PM

To clarify the 'coasting' bit:

Cable pulled out - normal 3 spd tranny
Cable pushed in:
1) Overdrive enabled (electrically) full engine braking
2) OD disable (freewheel)

You have to have the cable pulled out to go into reverse. Be sure the have the cable pulled out when parking - unless you trust your parking brake 100%

*1974k5blazer* · 04-24-2008, 02:58 AM

Speaking Of This Have You Ever Heard Of A Th350c With Some Type Of Overdrive!

Rogue 64 · 04-24-2008, 04:09 AM

My brother has 2 Turbo400 with an bolt on electric OD.
One behind the 6.2D, he plans to put in a 1962.

joe231 · 04-24-2008, 04:12 AM

Quote:

Originally Posted by kevindtimm

To clarify the 'coasting' bit:

Cable pulled out - normal 3 spd tranny
Cable pushed in:
1) Overdrive enabled (electrically) full engine braking
2) OD disable (freewheel)

You have to have the cable pulled out to go into reverse. Be sure the have the cable pulled out when parking - unless you trust your parking brake 100%

yes that is the tranny that used to be in the '66 before it was mine, guess I knew more about these than I thought

04-23-2008, 05:01 AM	#1
joe231 Registered User Join Date: Dec 2007 Location: Palmer, Alaska Posts: 13,821	what the heck is this? 3 speed overdrive? anyone heard of these??? linky __________________ *CHEVY ONLY*

04-23-2008, 05:23 AM	#2
kevindtimm Registered User Join Date: Feb 2007 Location: Allen,TX Posts: 170	Re: what the heck is this? 3 speed overdrive? Yes, they are EXTREMELY cool! I used to have one, but the rebuild cost was too much for me (previous owner not too forthcoming about condition) I would love to get another one, and know a guy locally who hoards them but a T5 is easier/less expensive to repair. If I had to choose? T85N w/OD (this item)

04-23-2008, 05:27 AM	#3
joe231 Registered User Join Date: Dec 2007 Location: Palmer, Alaska Posts: 13,821	Re: what the heck is this? 3 speed overdrive? i had no idea, what is the electrical stuff on it? is it a electric over drive. 3 speed plus over drive, or is 3rd gear the over drive? __________________ *CHEVY ONLY*

04-23-2008, 06:25 AM	#4
Fred T Cantankerous Geezer Join Date: Aug 2002 Location: Bel Aire, KS Posts: 6,264	Re: what the heck is this? 3 speed overdrive? 3rd gear plus OD. Electric switch for shifting in and out. Shifting was similar to a 2 speed rear on a 2 ton, it would shift after you switched it in and let up off the gas. __________________ Fred There is no such thing as too much cam...just not enough engine.

04-23-2008, 06:33 AM	#5
joe231 Registered User Join Date: Dec 2007 Location: Palmer, Alaska Posts: 13,821	Re: what the heck is this? 3 speed overdrive? wow, that is cool thanks the more i hear, the more convinced this tranny is what was in our '66 before my father in law swapped in a 283 and granny 4 speed, wish I knew what he did with the tranny __________________ *CHEVY ONLY* Last edited by joe231; 04-23-2008 at 06:41 AM.

04-23-2008, 07:03 AM	#6
greg64 Registered User Join Date: Dec 2007 Location: Kimberley, BC, Canada Posts: 799	Re: what the heck is this? 3 speed overdrive? So basically, are we dealing with a 2 speed in the extension housing? Never seen one of these animals.... __________________ Greg 64 GMC Suburban - 283, NV3500, 14 bolt 77 C10 swb - 292, SM465, 12 bolt

04-23-2008, 04:35 PM	#7
kevindtimm Registered User Join Date: Feb 2007 Location: Allen,TX Posts: 170	Re: what the heck is this? 3 speed overdrive? 3 speed tranny, 2 speeds (1:1 and .70:1). 3000 RPM @ 65mph or 2100 RPM @ 65mph SWEET!

04-23-2008, 05:10 PM	#8
Rogue 64 Ol' Blue Viking Join Date: Nov 2006 Location: north of Baton Rouge Posts: 172	Re: what the heck is this? 3 speed overdrive? I have seen Sag 4-speeds with those OD's adapted. I thought about doing that, but I'm afraid the 327 would twist it all up. __________________ Driving Paw-paws truck into the Sunset!

04-23-2008, 09:01 PM	#9
rickf Registered User Join Date: Dec 2005 Location: Lake Oswego, OR Posts: 318	Re: what the heck is this? 3 speed overdrive? At one time I was looking for one of these, they are hard to find. I found a lot of info on the net, though, e.g. http://www.jalopyjournal.com/forum/s...d.php?t=249066 One of the things I came across (don't know where it is now) said these overdrives free-wheel when coasting forward. So, e.g. cruising on the freeweay on long downhill you may as well be in neutral, no engine braking. I don't know if that applied to all or just certain models, there are apparantly couple different actual overdrives units used.

04-23-2008, 10:17 PM	#10
kevindtimm Registered User Join Date: Feb 2007 Location: Allen,TX Posts: 170	Re: what the heck is this? 3 speed overdrive? To clarify the 'coasting' bit: Cable pulled out - normal 3 spd tranny Cable pushed in: 1) Overdrive enabled (electrically) full engine braking 2) OD disable (freewheel) You have to have the cable pulled out to go into reverse. Be sure the have the cable pulled out when parking - unless you trust your parking brake 100%

04-24-2008, 02:58 AM	#11
1974k5blazer Account Suspended Join Date: Dec 2007 Location: Queen Creek AZ Posts: 243	Re: what the heck is this? 3 speed overdrive? Speaking Of This Have You Ever Heard Of A Th350c With Some Type Of Overdrive!

04-24-2008, 04:09 AM	#12
Rogue 64 Ol' Blue Viking Join Date: Nov 2006 Location: north of Baton Rouge Posts: 172	Re: what the heck is this? 3 speed overdrive? My brother has 2 Turbo400 with an bolt on electric OD. One behind the 6.2D, he plans to put in a 1962. __________________ Driving Paw-paws truck into the Sunset!

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