Granny Gears Too Low..Solutions ?
 

The granny low 4 speed in my 69 k10 is too low for driving on the highway, or any speed over 40 mph. I am looking for a way to be able to go faster at lower rpms, what would be the best way of doing this? Is changing the gear ratio a good idea? or replacing the transition itself? Please give me your input! thanks!:chevy:

Re: Granny Gears Too Low..Solutions ?
 

Welcome to the board and :wop:. What rear gears do you currently have? What rear end is in the truck? You have 3 options. Change the transmission, change the rear gears, or get bigger tires. All depends on your budget. So, what is your budget? What is your fabrication / mechanical skill level? Lots of good information from members of this board, so you came to the right place. Hopefully with more info, we can get you a solution. In the meantime do some searching on Gear Vendors, NV4500, overdrive upgrade, and see what others have done.

Re: Granny Gears Too Low..Solutions ?
 

Now just changing the transmission in itself is not gonna help unless you go to a newer type overdrive. Without the overdrive they all end up at the same place 1:1. The gears are probably stupid low but with the K truck you have to change the fronts also so that is a double hit in the wallet. Taller tires will help some but if your geared real low not much gain to be had. To get it to a comfortable place all three may have to be done. I have a one ton that has 5:38 gears and I am thinking a overdrive and a 4:10 rear gear then it will cruise more comfortably. you know there is a lot more riding done in trucks than back then they went to work and gas was also about 75 cents a gallon too. Jim

Re: Granny Gears Too Low..Solutions ?
 

Take it out of low range.

Re: Granny Gears Too Low..Solutions ?
 

Take off in "2nd" gear. The "granny low" 4 speeds are basically a 3 speed with low range. I had an SM465 in a 1979 GMC K25 and only used "1st gear" (marked L) when pulling or hauling. I always took off in 2nd gear for normal driving. Which is marked 1st gear.

Cruising at 3,000 to 3,500 RPM's isn't going to hurt anything.

Gary

Re: Granny Gears Too Low..Solutions ?
 

Change the gear ratio or go with an overdrive transmission. All transmissions will be 1:1 final drive ratio, then there is overdrive. Granny gear refers to 1st gear which is a major reduction gear for getting trucks going when being worked hard and/or for creeping along for certain tasks without riding the clutch
How fast do you want to go? Do you know your gear ratio? I have no problem driving trucks with 4.10 ratio on the hiway. And you don't "have to" drive as fast as the rat race you know. 65-70 will get you there just fine. These trucks have always done what was asked of them, which is the original reason they gained such popularity.

Re: Granny Gears Too Low..Solutions ?
 

How do i figure out what gear ratio it has without opening up the differential? i am no mechanic, this is my first truck, got it about a year ago when i was 17. learned a lot since and looking to learn more. i would probably be willing to spend up to 1000$ to fix the problem, but of course less is always ideal. seems like changing the gear ratio might be best, I'm trying to keep it mostly stock, though ive got 31 inch tires on already. this thread is incredible, thanks guys!

Re: Granny Gears Too Low..Solutions ?
 

Look on the right axle tube on the rear end there should be some letters. 373=HA 307=HB411=HR,JQorTS

Re: Granny Gears Too Low..Solutions ?
 

Well look in your glove box first and see if a ratio is listed on there. Next there may be a tag on the rear end held on by one of the rear cover bolts if not there may be a code stamped in to the axle tube that is about the only way other than marking the drive shaft and tire then turn the drive shaft and count the turns on thew tire. Drive into driven, IE ten turns on the driveshaft 40 turns on the tire=4:10 of course lots of people do this and turn the drive shaft ONE revolution then count the tire turns,= one driveshaft rev =3 and 3/4 turn of tire =3:73 gears. That is the way most people do the gear search thing.
I'm sure there probably is a you tube tutorial on how to do that rear gear search or something like that so you can know what your dealing with.
Why not find out what you have then post up so we then can discuss your best options then.
Do you have a Tach in the truck to get some kind of idea where the motor is while cruising? It isn't gonna be like the newer truck/cars of recent because of the overdrives that they have . the engine may not be revving or working as hard as you think it may just seem that way.

Re: Granny Gears Too Low..Solutions ?
 

In what position is the floor shifter for the t-case?

Re: Granny Gears Too Low..Solutions ?
 

Its not in 4 low, I'm talking 4 high being too low. the other shifter has only 2 options-4high and 4low

Re: Granny Gears Too Low..Solutions ?
 

Yeah, 40 feels like top speed? Like KW has asked, what position is the transfer case shifter in? Is it all the way forward? Pull it all the way back, then push it lightly till you feel it slip into the next position. Either it's you aren't used to trucks with lower gears and no overdrive and everything is cool, or you're in 4LO.

From forward to back it's: 4LO-N-2H-2L....4wd low (makes gearing 2x lower), then neutral (even with transmission in gear it won't move), 2wd high (normal 2wd), and all the way back is 4wd high (same gearing as 2wd but 4wd). Do you have one of the transfer case knobs with no markings? Is that shifter bent towards your leg or is it bent straight back towards the seat? Could you post a picture? How about pics of the truck??

Re: Granny Gears Too Low..Solutions ?
 

If it's not in 4lo how do explain only being able to drive only 40 mph. AND what other shifter

Re: Granny Gears Too Low..Solutions ?
 

The other shifter is the transfer case shifter, right? It has the pattern I explained. Have you found neutral on the transfer case lever? So, what position is the shifter, back or forward?

Re: Granny Gears Too Low..Solutions ?
 

its in 2 high, and when i say 40 mph tops i mean at a comfortable cruising speed, go up to 55-60 and the engine is roaring. and yes i have the oil pressure gauge that came stock working, at 55 I'm pretty much maxed out.
i also looked on the rear axle, stamped on the right tube it says 1 2 3 4 5, upside down. does this mean the axle isn't stock?
thanks for bearing with me people, its my first thread. il post pictures when i can

Re: Granny Gears Too Low..Solutions ?
 

also now that I've been taking a closer look, it really seems that there are only 3 positions on my transfer case shifter, 2 high, N, and 2 low from forward to back. how do i engage 4x4? in the past I've just locked the hubs for 4x4 use. i am somewhat sure that this is not a related issue, however if anyone feels differently please let me know!

Re: Granny Gears Too Low..Solutions ?
 

Are you saying your truck is not equipped with lock-out hubs? Just a bolt-on plate with a bulge in the middle? If so, the hubs are always engaged to spin with the axle. The axle will only spin when the driveshaft does which should only happen when the shifter is in 4HI or 4LO. I think you are only feeling one side of neutral and the other. It's a less noticeable feel between 4HI and 2HI right next to each other.

I think you are just not used to a lower geared truck combined with no overdrive. I've seen this before with younger people who came up with newer O/D high geared cars

Re: Granny Gears Too Low..Solutions ?
 

Dana axles came with a tag on one of the cover bolts that will tell you the ratio if a PO hasn't removed them. Otherwise if it is something other than stock should be on the SPID. Sounds like you have 4.57 gears most likely. One cure is bigger ties. 35's would help manage that RPM on the road, but requires a lift. You might be able to run a skinny 34" tire withou a lift which almost gets you there.

Otherwise, gear change or OD trans. I like/prefer the granny 4 speed in a truck so would be looking at gears. Great time to do a disc conversion as well.
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Re: Granny Gears Too Low..Solutions ?
 

I'm betting this is it. These trucks can handle cruising at 3,000 to 3,800 RPM's at highway speeds all day long. It's how they were built. Back then gas was .40 cents a gallon no one cared that they would pass everything but a gas station. Small blocks don't start making power until they get a little RPM in them anyways. ;)

Gary

Re: Granny Gears Too Low..Solutions ?
 

Always good to see someone that gets the old truck bug when they are young. Better news is there has been a lot of good suggestions posted so far. So on your list, the first thing you need to do is post pictures (exterior, interior, rear differential), check the inside of the glove box, and check the gear ratio as per what hugger6933 suggests. Also what is your budget?

Re: Granny Gears Too Low..Solutions ?
 

The roaring could be his fan blade assy, just seems like its screaming, put a tach on it even with 4.56 gearing you should be able to run 55-60 with a small block without major issues

Re: Granny Gears Too Low..Solutions ?
 

http://67-72chevytrucks.com/vboard/a...1&d=1435166967


this is my tranny and rear axle, anyone recognize either of them?

Re: Granny Gears Too Low..Solutions ?
 

Thanks for the input everybody, the issue is not with the transfer case me thinks, but rather with the nature of the transition and gearing being too low for practical freeway use. i do a fair bit of free way driving, and would like to be able to cruise along with lower rpms. so overdrive or change the gear ratio is what I've narrowed to down too, i like the look of the stock sized tires :uhmk: and want to keep them. so i need to figure out my gear ratio, my back axel says 1 2 3 4 5

Re: Granny Gears Too Low..Solutions ?
 

The transfer case is a Rockwell. It is a T221. There were several variations '62 to '69. Shift pattern for the 2WD 4HI Neutral 4LO. the 2WD is closest to the firewall, 4LO is closest to the seat. Torque Ranger from Advanced Adaptors is another possiblity for an overdrive with the SM465. Lots of work to do it.

Re: Granny Gears Too Low..Solutions ?
 

Jack a tire up, put the tranny in neutral, spin the tire twice and see how many times the driveline turns and report back.

Re: Granny Gears Too Low..Solutions ?
 

Is there a tag on either the front or rear diff covers? It will be under one of the bolts holding the cover on

Re: Granny Gears Too Low..Solutions ?
 

Should be easy to get a set of 1/2 ton 4x4 axles with either 3.07 or 3.73 gears from a 70's truck and swap 'em in. Get disc brakes that way too.
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Re: Granny Gears Too Low..Solutions ?
 

A few ideas:
The diffs need the oil changed or have almost none anyway. Drop the $20 and pull a cover to find out for sure. The ratio is stamped on the ring gear.
With a 4x4, swapping diffs isn't so simple because doners (73+) don't have the right spring mount spacing. I'm guessing this is a half ton. So a 2x diff swap is impractical for $1k.
Get a tach and find out what the engine is turning in reality. This is a 46 year old truck. It isn't like a new vehicle and what its acting like is normal for the time.
What engine is in it? A 6 or original 6 truck would have a lower ratio than a V8.
I'm pretty sure the 69 trucks had a married TC, so a trans swap to OD is impractical for $1k.

Re: Granny Gears Too Low..Solutions ?
 

Spring perches were on different centers and one shock mount is on the wrong side.

Re: Granny Gears Too Low..Solutions ?
 

So it doesn't bolt right in. Neither does a gear set or a differential set itself up.

I have 3/4 ton axles from an '86 in my '72. I removed and reused the donors spring perches. I used the OEM shock mounts from my original axle. No biggee. And even if you had to pay to have that done, no more than a couple $100.

I paid $300 for the Suburban with a broken motor. I bought another '83 3/4 ton sub for $200 and a '76 Blazer for $300. They are out there, and they are cheap. If you can't do this swap for $1000 you didn't try. 1/2 ton axles are out there it seems all over because 3/4 ton such a better choice IMO but if driveability is the goal, the 1/2 tons will work great.

If you have the whole thing apart anyway, you could also swap the gear set into the existing 12 bolt housing (assuming you get a '73-'79 donor and not an 8.5" 10 bolt truck). Either way, the truck will be much more driveable and safer with discs.

Re: Granny Gears Too Low..Solutions ?
 

A tachometer to see what actual RPM the engine is turning would be the first step. Converting to a clutched cooling fan would greatly reduce the roar. Seeing on the tach that the engine isn't actually screaming, and not hearing the fan roaring, may be all you need to feel OK with driving it at highway speeds.

Re: Granny Gears Too Low..Solutions ?
 

Benbloom -- a Rockwell T-221 transfer case is unusual in a '69 K/10. I thought 1968 was the [first and-] last year for an SM 465/T221 set up. (With GMC and Canadian hold-outs until they ran out in '69.) With a Marin County location, the most statistically probable origin for a GM truck would be Fremont [code Z] across the Bay. But then we all know how these rigs get around.
Also after 40+ years, who knows what a PO may have cobbled together, just to get back on the road. You could even have the SM420 4-speed, also a Granny Gear tranny, but with even lower ranges in 1-2-3. Also you never use 1st [Granny] unless you have a full load of riprap in the bed. SM420s last production year was 1967.
The VIN would be helpful. Or a pic of the SPID. You can use X's for the last five numbers, if you're security conscious.

That being said, I have heard the Rockwell T221 was very noisy in its own right, even on a good day. I have a core SM465/T221 [that was misrepresented to me as a 205 by an long-gone junkie] I thought 1968 was the only year for that combo. I hear it's a strong TC but replacement parts are hard to get now.
One more thing, make sure the gear oil levels are up to spec. SAE 90 GL-5 will work. They get loud if the levels are too low. [Just before they burn out.]

GASoline71-- I remember premium ARCO selling for .25/GAL in Hollywood in 1969. We would've rioted if it was as high as .40!

Re: Granny Gears Too Low..Solutions ?
 

'68OrangeSunshine- i usually start in 2nd, how do i figure out what trans i have? it is very noisy, the thing is an absolute gear. il try to get the vin number on here asap!
thanks everyone for the help, i figure il probably just live with the very low gears, and no, its not that I'm just not used to the old trucks, driving my friends k10s with the automatic tranny there is a very noticeable difference. again, thanks everyone, il get the vin asap

Re: Granny Gears Too Low..Solutions ?
 

Both the SM 420 and the SM 465 have the compound low 1st gears.
The only way to tell 'em apart is by the Reverse Gear position:
420-Reverse is toward you and back [left of center of #2 on the gearshift pattern]
465- Reverse is away from you and back, off center from #4.
1-2-3-4 Are in standard H pattern.
You might also look on the SPID for a transmission RPO code. It may be listed as "SynchroMesh Transmission'', [Which they both are.]
<<M20 4 Speed>> may be a 465. This is all from memory.

Re: Granny Gears Too Low..Solutions ?
 

reverse is to the right and towards the bench ?

Re: Granny Gears Too Low..Solutions ?
 

Yeah. On the 465.

Re: Granny Gears Too Low..Solutions ?
 

My K10 (72 w/ sm465/np205) isn't quite back together yet to compare, but if you're out near either Discovery Bay or in SF with the truck, I'd be happy to at least take a ride with you and tell you if it sounds normal.
I was looking at adding a Gear Vendors OD and after a lot of research I found a guy up in Sac that rebuilt and sold them, he told me with my ratio (3.07) it wouldn't do me any good.

Re: Granny Gears Too Low..Solutions ?
 

I have a 68 K10 with the Rockwell 221 and 4 speed.. I thought 68 was the last year for the Rockwell?
1968 Chevy K10 factory information shows the standard axle gear ration as 3.73 with no optional ratios available as original equipment. I will assume 69 is the same but of course the gears might have been changed over the years.
3.73's with typical 235/15 tires is around 2600-2700 rpm at 60 mph. While not the 1400 rpm of a new truck it's not all that much engine speed and you can cruise all day at 65 ...
My 68 with a 250 sounds busy at 60 mph but I pay no attention to and drive on....It's an old truck with minimal or no sound deadening...Not a 2015 Silverado ;)