Speedo reads fast, I assume that my,, - Page 3

batty1214 · 01-10-2009, 09:12 PM

or, do that^^^^^ that brad is a smart guy

!!!

mortar · 01-13-2009, 09:18 PM

I'm going to ask this question in here, if looks like I should start a new thread I will.

Like I've posted before my truck 78 GMC 3/4 ton, 350 with a TH400 drives like a dream, motor, tranny, front end and suspension.

One thing when I'm on the highway at around 55 approaching 60+ it almost feels like it needs another gear.

Could the truck being setup gear wise for hauling a trailer have something to do with this.

Oh the truck also has a shift kit, I'm going to assume that it was setup to shift better when hauling a load.

gmctrucks · 01-14-2009, 12:43 AM

I got it go out and get a ticket from a police that will let you know for sure if it's off. Well it would and you would have it on black & white written on paper or blue & white depends what color pen he has. I think I deserve rep points for figuring this out with the law helping you?
He! He! GMC
PS-I agree change out the color of gear till you find the right one or a good shop should know what color to go with.

leolkfrm · 01-14-2009, 04:52 AM

Is it a shift kit or secondary gearbox? What is the rpm at 55mph? is the sticker still in the glovebox or tag on the rear? back then they usually used a 411 for pulling

mortar · 01-14-2009, 06:44 AM

It's a shift kit the rear end is not original to the truck it's from a rear end specialty shop.

Don't know what the RPMs are don't have a tach.

mortar · 01-16-2009, 07:17 AM

So is possible it could be the rear end ?

leolkfrm · 01-16-2009, 07:24 AM

the rear end may have caused the error, but if you put the correct gear in the tail piece all will be good again. do you have a speedometer shop around you?

mortar · 01-16-2009, 07:35 AM

Sorry, I was actually thinking about my second query, where the truck almost seems like it should shift in to another gear at 55\60 + MPH.

01-10-2009, 09:12 PM	#21
batty1214 Senior Member Join Date: Nov 2008 Location: Vernal Utah Posts: 1,135	or, do that^^^^^ that brad is a smart guy!!!

01-14-2009, 04:52 AM	#24
leolkfrm Senior Member Join Date: Mar 2008 Location: N.Y. Posts: 4,300	Is it a shift kit or secondary gearbox? What is the rpm at 55mph? is the sticker still in the glovebox or tag on the rear? back then they usually used a 411 for pulling __________________ 4 wheels move the body 2 wheels move the soul B.W.A.I

01-16-2009, 07:24 AM	#27
leolkfrm Senior Member Join Date: Mar 2008 Location: N.Y. Posts: 4,300	the rear end may have caused the error, but if you put the correct gear in the tail piece all will be good again. do you have a speedometer shop around you? __________________ 4 wheels move the body 2 wheels move the soul B.W.A.I

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01-13-2009, 09:18 PM	#22
mortar Senior Member Join Date: Oct 2008 Location: Tulsa Posts: 64	I'm going to ask this question in here, if looks like I should start a new thread I will. Like I've posted before my truck 78 GMC 3/4 ton, 350 with a TH400 drives like a dream, motor, tranny, front end and suspension. One thing when I'm on the highway at around 55 approaching 60+ it almost feels like it needs another gear. Could the truck being setup gear wise for hauling a trailer have something to do with this. Oh the truck also has a shift kit, I'm going to assume that it was setup to shift better when hauling a load.

01-14-2009, 12:43 AM	#23
gmctrucks Senior Member Join Date: Nov 2006 Location: Houston,Texas Posts: 4,033	I got it go out and get a ticket from a police that will let you know for sure if it's off. Well it would and you would have it on black & white written on paper or blue & white depends what color pen he has. I think I deserve rep points for figuring this out with the law helping you? He! He! GMC PS-I agree change out the color of gear till you find the right one or a good shop should know what color to go with.

01-14-2009, 06:44 AM	#25
mortar Senior Member Join Date: Oct 2008 Location: Tulsa Posts: 64	It's a shift kit the rear end is not original to the truck it's from a rear end specialty shop. Don't know what the RPMs are don't have a tach.

01-16-2009, 07:17 AM	#26
mortar Senior Member Join Date: Oct 2008 Location: Tulsa Posts: 64	So is possible it could be the rear end ?

01-16-2009, 07:35 AM	#28
mortar Senior Member Join Date: Oct 2008 Location: Tulsa Posts: 64	Sorry, I was actually thinking about my second query, where the truck almost seems like it should shift in to another gear at 55\60 + MPH.