Dumb question 3 or 4 Speed Muncie

[Legolas894]

Ok, in my GMC 910 (which is like a C10), I have a mystery motor that I think is a 283 V8. According to the VIN, it should have had a I-6. It also had a column shift replaced with a floor shift. Anyway, I put a new speedometer cable and red 21 tooth driven gear on tonight to get the speedometer to work (and it does yay!). While under the truck in the rain, I could actually see the casting numbers on the transmission. It was 3857584GM and another number is 3851325. A quick websearch says that this is a 4 speed transmission? I can only find three forward gears while driving and reverse is ok. The floor shift pattern is also a little strange Reverse all the way left and forward, 1st straight down but a little to the right, second over left and straight up and third straight down.

Does this sound right or is there a missing gear somewhere??

I feel stupid asking!!

[Longhorn Man]

sounds like a 3 speed to me.

[Elephanthead]

my 67 4 speed is

...1 3

R 2 4

[special-K]

Second over right,correct?Not over left,right?

[Legolas894]

Yes-Sorry, Second over right, Third straight down from Second.

R 2
1 3

[Skirkpat]

While you were looking did you count the shifter levers? or more importantly the shafts that they bolt too?

Two shifter "bolts" or shafts = 3 speed
Three " " '" " " " " = 4 speed

the extra one will be right in front of where your speeo cable hooks up on the tail shaft.

[Legolas894]

I'll try to get a picture tomorrow. I'm just getting a grasp of all that this truck has but it would be nice if it had a 4th gear. Third seems to rev pretty high at 50MPH for me (don't have a TACH either).

[Skirkpat]

three speed:

[69halfton]

dont know about down where you are, but here it was mightly cold and rainy to be doing work on the ground under your truck! props for that..

..and it all seems to ad up to a three speed...

can the 3spd and 4 spd cases be interchanged? possibly somebody took the guts of one and put it in another case? just throwing it out there i dont really know much about standards

[Longhorn Man]

it doesn't matter if your truck is a 2 speed, 3 speed, or a 4 speed. They all have a 1 to 1 final gear ratio.
In otherwords, if you have a 4 speed, you'd be ravin just as high as if you had a 3 speed.
To drop your RPMs you need either a rear axle gear ratio swap, or an over drive tranny.

[Skirkpat]

Originally Posted by Longhorn Man

it doesn't matter if your truck is a 2 speed, 3 speed, or a 4 speed. They all have a 1 to 1 final gear ratio.
In otherwords, if you have a 4 speed, you'd be ravin just as high as if you had a 3 speed.
To drop your RPMs you need either a rear axle gear ratio swap, or an over drive tranny.

Unless he can't get out 2nd gear, Like "Sammy the Red Rocker"

[special-K]

I`d be ravin`,too.(about how high it was revvin`)
Man,am I askin`for it.Relax guys,he knows am justa keedin`.

[Longhorn Man]

you got me Tim!
Ravin, revin, what ever.
There's a reason I hardly ever get on ppl for typing skills

[Legolas894]

Actually, Longhorn man just solved my problem. If the final gear is 1:1 then it is really the back end that needs work. I get up to the third gear with no issues so really, I need a higher gear ratio in the back.

Great points from all.

Jason

[Critter]

According to this, you at least have a 4 speed tail housing. I couldn't find anything saying that the identical tail housing was used on both the 3 and 4 speeds. But the year model could make it correct for your truck assuming the tail housings were interchangeable.

http://www.5speeds.com/casting.html

I’m betting you have the original 3 speed. I doubt someone would take the time to put in a 4 speed but not get a shifter for it to work properly. However, if for some reason that is the case and you are stuck in 3rd gear of a 4 speed, then it would DEFINITLY be beneficial to your RPMs to find 4th gear. While finding an additional gear would be cool, from the way you described your shift pattern, I’m betting it’s a three speed like others have said.

[Legolas894]

Yeah-a 4-speed seems to be just a dream! The original I-6 would have had a three speed so mabye the PO just switched the engine to 283 and left the 3-speed. It was a farm truck for use in apple/peach orchards so probably wasn't ever going to go too fast. I still have to find the numbers for the rear-end to see what the gear ratio is.

Thanks for your reply.

[Legolas894]

Originally Posted by Legolas894

Ok, in my GMC 910 (which is like a C10), I have a mystery motor that I think is a 283 V8. According to the VIN, it should have had a I-6. It also had a column shift replaced with a floor shift. Anyway, I put a new speedometer cable and red 21 tooth driven gear on tonight to get the speedometer to work (and it does yay!). While under the truck in the rain, I could actually see the casting numbers on the transmission. It was 3857584GM and another number is 3851325. A quick websearch says that this is a 4 speed transmission? I can only find three forward gears while driving and reverse is ok. The floor shift pattern is also a little strange Reverse all the way left and forward, 1st straight down but a little to the right, second over left and straight up and third straight down.

Does this sound right or is there a missing gear somewhere??

I feel stupid asking!!

Well-Guess what-I found all four gears!!!!

R 1 3
2 4

How dumb I was. I was going from R to 2, then 3 and 4 (always not starting in first). I think my transmission must be worn because you have to hunt for 1st and it's way too easy to go into 3 and miss 1. Feel kind of foolish but I guess you always learn something from these trucks.

Have a great day and thanks for all the help. Starting on the drum brakes all around this week. Got all the parts.

[PanelDeland]

And first was way lower than the second you thought was first so you still rev high on the hiway.A rear gear change will make it better but you probably have a 3:73 ratio and changing to a 3:08/3:07 will be too much.Larger diameter tires in the rear may help some but will probably not be a cure all.The ultimate set-up is possibly a Gear vendors over/under drive unit but you really better be sitting down and maybe have medical staff standing by when you price one.

[Skirkpat]

your tranny may be alright, the old 4 speeds are tough to wear out. I would look at the shifter first, I had to rebuild the one on the three speed that I posted earlier. I went to ace harware, and bought teflon bushings in the right outside/ inside diameter and ground them down to the right thickness. cost about 3.oo.

[Legolas894]

Originally Posted by PanelDeland

And first was way lower than the second you thought was first so you still rev high on the hiway.A rear gear change will make it better but you probably have a 3:73 ratio and changing to a 3:08/3:07 will be too much.Larger diameter tires in the rear may help some but will probably not be a cure all.The ultimate set-up is possibly a Gear vendors over/under drive unit but you really better be sitting down and maybe have medical staff standing by when you price one.

I know what you mean about prices. Just spent $700 on drums, wheel cylinders, shoes, seals, tie rods! I've got to cool it for awhile or the wife will be looking in the yellow pages for "Divorce Lawyer"!!

Nothing by itself seems too expensive but by the time you get it all together plus grease, brake cleaner, fluid, coolant, oil, etc. Man!!

[1970 Bowtie]

If reverse is left and up,1st straight down,2nd over right and up,and 3rd straight down from 2nd.I wouuld say that is a 3 speed.Have same pattern on my 3 speed

[Legolas894]

No, Reverse is left and up, First is right and up, 2nd straight down, third right and up and fourth straight down. Hard to make the picture:

R--1--3
---2--4

[1970 Bowtie]

well at least you know its a 4 speed.

[special-K]

That`s cool to know!It sounds like the ****er is worn,making gear location hard to find.You may find a 3.08 ratio will work fine for you.Figure your 1st will be lower than a 3 spd.Also,you may have a 4.10 rear.