Transmission Question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

eglide78 · 07-27-2013, 06:27 PM

I need some "advice". I scored a 1971 GMC Custom Camper 2500 Series with 46K original miles and all original. On the glove box door it says M49 Turbo Hydra-Matic transmission. As I am going down the road I can feel it shift from what I presume is 1st... to 2nd(very smooth) to 3rd at around 30 MPH and it feels like it should shift once more at around 45 - 50 but it does not. Doing 55 MPH it seems as though the engine is pulling some substantial RPMs... should it be shifting one more time? What would keep it from going into that final gear... The truck runs and drives great except for this issue. It was bought brand new and when Grandpa passed he left it to his son. When his son couldn't drive anymore he turned the truck over to his daughter and that's who I got it from... she had it about 10 years.
Any assistance on this transmission shifting question will be greatly appreciated.
Thank you

turp mcspray · 07-27-2013, 06:33 PM

Your trans only has 3 forward gears. Since it is a 3/4 ton, it may have 4.10 gears, which would make the engine rpm, higher than you are used to.

eglide78 · 07-27-2013, 06:47 PM

I guess so then... what would be optimal gear ratio so that the engine is not working quite so hard at about 60 MPH?

msgdsrf · 07-27-2013, 07:18 PM

Depends on rear tire size.

**Stocker** · 07-27-2013, 07:25 PM

And if you have an Eaton HO52, taller gears are not available. Well, maybe 3:73s but that's not much change. You'd have to swap to a different rear end. I'd start by verifying the ratio.

**Already Gone** · 07-27-2013, 08:01 PM

If no one has changed anything on the truck and it has the 350 engine you would have 4:10 gears and 4:57 were optional and would show on the spid label on the inside of the glove box lid. If you have a 402 engine you will have 3:54 gears and optional were 4:10s and that too will show up on the spid label. We all love to see pictures of trucks on here so if and when you can, post some pictures.
Posted via Mobile Device

eglide78 · 07-27-2013, 09:30 PM

I will post up some pictures for sure... Thanks all for the information... It is a 350 and nothing has been changed on this truck. Even still has the AM Radio in it, original carpeting. It's got some rust here and there but nothing like my '64...

On the glove box label it says "Turbo Hydra-Matic and under option it says N40

Thanks again and I welcome any and all advice...

eglide78 · 07-27-2013, 09:42 PM

Here are some pics from yesterday... I had to keep the '64 in the pictures so it didn't feel jilted...

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**Already Gone** · 07-27-2013, 10:10 PM

Even sideways that is a great looking truck.
Posted via Mobile Device

eglide78 · 07-27-2013, 10:11 PM

Quote:

Originally Posted by Already Gone

Even sideways that is a great looking truck.
Posted via Mobile Device

Are the pics coming up sideways? They aren't showing that way to me....

**Already Gone** · 07-27-2013, 10:18 PM

Quote:

Originally Posted by eglide78

Are the pics coming up sideways? They aren't showing that way to me....

yes they are on my IPad but everything else is as it should be.
Posted via Mobile Device

**Stocker** · 07-27-2013, 11:00 PM

Not sideways on my home computer.... truck looks great btw!

eglide78 · 07-27-2013, 11:03 PM

Cool. Weird. It does come up sideway on my iPad also. Thanks.
Posted via Mobile Device

slow-1 · 07-28-2013, 08:47 AM

Nice truck...saw your story about the naming it after the lady you got it from...you are a good man.

You can also change transmissions to one with overdrive to get your rpms down...or put on glass packs and enjoy the music!

07-27-2013, 06:27 PM	#1
eglide78 Registered User Join Date: Jul 2013 Location: Dallas, GA Posts: 30	Transmission Question I need some "advice". I scored a 1971 GMC Custom Camper 2500 Series with 46K original miles and all original. On the glove box door it says M49 Turbo Hydra-Matic transmission. As I am going down the road I can feel it shift from what I presume is 1st... to 2nd(very smooth) to 3rd at around 30 MPH and it feels like it should shift once more at around 45 - 50 but it does not. Doing 55 MPH it seems as though the engine is pulling some substantial RPMs... should it be shifting one more time? What would keep it from going into that final gear... The truck runs and drives great except for this issue. It was bought brand new and when Grandpa passed he left it to his son. When his son couldn't drive anymore he turned the truck over to his daughter and that's who I got it from... she had it about 10 years. Any assistance on this transmission shifting question will be greatly appreciated. Thank you

07-27-2013, 06:33 PM	#2
turp mcspray Registered User Join Date: May 2007 Location: Rapid City South Dakota Posts: 2,359	Re: Transmission Question Your trans only has 3 forward gears. Since it is a 3/4 ton, it may have 4.10 gears, which would make the engine rpm, higher than you are used to. __________________ Turp Mcspray New life for an old 2wd, farm blazer http://67-72chevytrucks.com/vboard/s...d.php?t=505987 My Blazer build http://67-72chevytrucks.com/vboard/s...d.php?t=342299

07-27-2013, 06:47 PM	#3
eglide78 Registered User Join Date: Jul 2013 Location: Dallas, GA Posts: 30	Re: Transmission Question I guess so then... what would be optimal gear ratio so that the engine is not working quite so hard at about 60 MPH?

07-27-2013, 07:18 PM	#4
msgdsrf Registered User Join Date: Jul 2012 Location: White Salmon, WA Posts: 263	Re: Transmission Question Depends on rear tire size.

07-27-2013, 07:25 PM	#5
Stocker 20' Daredevil (Ret) Join Date: May 2003 Location: Jefferson State Posts: 13,562	Re: Transmission Question And if you have an Eaton HO52, taller gears are not available. Well, maybe 3:73s but that's not much change. You'd have to swap to a different rear end. I'd start by verifying the ratio. __________________ - Mike - 1972 K20 LWB 350/350/205 RIP El Jay

07-27-2013, 08:01 PM	#6
Already Gone 70+ ( Old Skool Club ) Join Date: Nov 2003 Location: Saskatoon, Saskatchewan ,Canada Posts: 9,104	Re: Transmission Question If no one has changed anything on the truck and it has the 350 engine you would have 4:10 gears and 4:57 were optional and would show on the spid label on the inside of the glove box lid. If you have a 402 engine you will have 3:54 gears and optional were 4:10s and that too will show up on the spid label. We all love to see pictures of trucks on here so if and when you can, post some pictures. Posted via Mobile Device __________________ 1972 C10 Custom/Deluxe 613 Highlander 406/700R4 1999 White Tahoe LS 4x2 with Z56 Police Package 1992 K1500 GMC Suburban Members I have personally met: MusicMan70 - HeavyD - ChewyChevy67 - StingRay -71SWB4x4 - 67 Burb - DeadheadNM - too much stuff - bc65 - das601 " Circumsatances Do Not Change Responsibility " " The Sky is not the Limit, Your Mind is." Marilyn Monroe .. RIP Charlie Watts 1941 - 2021

07-27-2013, 09:30 PM	#7
eglide78 Registered User Join Date: Jul 2013 Location: Dallas, GA Posts: 30	Re: Transmission Question I will post up some pictures for sure... Thanks all for the information... It is a 350 and nothing has been changed on this truck. Even still has the AM Radio in it, original carpeting. It's got some rust here and there but nothing like my '64... On the glove box label it says "Turbo Hydra-Matic and under option it says N40 Thanks again and I welcome any and all advice...

07-27-2013, 09:42 PM	#8
eglide78 Registered User Join Date: Jul 2013 Location: Dallas, GA Posts: 30	Re: Transmission Question Here are some pics from yesterday... I had to keep the '64 in the pictures so it didn't feel jilted...

07-27-2013, 10:10 PM	#9
Already Gone 70+ ( Old Skool Club ) Join Date: Nov 2003 Location: Saskatoon, Saskatchewan ,Canada Posts: 9,104	Re: Transmission Question Even sideways that is a great looking truck. Posted via Mobile Device __________________ 1972 C10 Custom/Deluxe 613 Highlander 406/700R4 1999 White Tahoe LS 4x2 with Z56 Police Package 1992 K1500 GMC Suburban Members I have personally met: MusicMan70 - HeavyD - ChewyChevy67 - StingRay -71SWB4x4 - 67 Burb - DeadheadNM - too much stuff - bc65 - das601 " Circumsatances Do Not Change Responsibility " " The Sky is not the Limit, Your Mind is." Marilyn Monroe .. RIP Charlie Watts 1941 - 2021

07-27-2013, 11:00 PM	#12
Stocker 20' Daredevil (Ret) Join Date: May 2003 Location: Jefferson State Posts: 13,562	Re: Transmission Question Not sideways on my home computer.... truck looks great btw! __________________ - Mike - 1972 K20 LWB 350/350/205 RIP El Jay

07-27-2013, 11:03 PM	#13
eglide78 Registered User Join Date: Jul 2013 Location: Dallas, GA Posts: 30	Re: Transmission Question Cool. Weird. It does come up sideway on my iPad also. Thanks. Posted via Mobile Device __________________ 1964 C10... work in progress 1971 GMC 2500 Sierra Custom Camper

07-28-2013, 08:47 AM	#14
slow-1 Registered User Join Date: May 2013 Location: Central NC Posts: 830	Re: Transmission Question Nice truck...saw your story about the naming it after the lady you got it from...you are a good man. You can also change transmissions to one with overdrive to get your rpms down...or put on glass packs and enjoy the music! __________________ 1972 Cheyene C-10 "Ole Green" My Grandfathers truck (early 70's to 1983) My first vehicle (1983) Original 350 (3 rebuilds) 700R4 from Bowtie Overdrives



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