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#1 |
1969 Custom 30 wrecker
Join Date: Sep 2001
Location: Pottsville, Pa
Posts: 2,611
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I got my 71 C20 on the road today and this transmission sure leaves alot to be desired.
I knew 1st gear was all but useless but 2nd is way too low as well. Pull out in 2nd and by the time you get movement, you have to shift to 3rd which then feels too high of a gear. And to go from 3rd to 4th? Wow, another large jump. It's fine if your going down hill but heaven forbid your going up hill during that 3-4 shift. Your choice is to rev the engine up the hill in 3rd or hit 4th and bog your way up. Sure seems odd to me. The gear ratio's seem way out of whack. Certainly not going to be the best for fuel mileage. lol My truck has a 4:10 Eaton rear by the way. I have a rebuilt 1984 305 from a Camaro in it now which runs good. I just want to see what others think of these transmissions.
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Bob 63 Impala 283/PG/3.36 (under restoration) 66 Impala 327/PG/3.36 66 Chevelle SS 409/M22/3.55 69 Chevelle 307/PG/3.08 (future restoration) 69 C10 short stepside 454/TH350/3.73 69 Custom 30 tow truck 350/4 spd/4.10 (resto done, CRUISIN TIME!) 71 Cheyenne 20 fleetside 350/4 spd/4.10 71 Chevelle 6/PG/3.08 72 Chevelle 454/M21/4.10 |
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#2 |
Nothing to see here.....
![]() Join Date: Jun 2007
Location: Shawnee, KS
Posts: 4,625
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Re: 4 speed w/granny gear...lets talk...
unless your in the business of stump pulling or rock crawling, they are useless imho. However they are bulletproof!
4.10's are quite low for the M-20/SM465. My truck has 3.07's and it's not too bad, but oh do I pray for a wide ratio M-21 or M-22 someday...
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Doug ![]() ![]() The democracy will cease to exist when you take away from those who are willing to work and give to those who would not. Thomas Jefferson Last edited by tcb-1; 05-14-2009 at 06:26 PM. |
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#3 |
Registered User
Join Date: Dec 2006
Location: Porter Ranch, CA
Posts: 978
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Re: 4 speed w/granny gear...lets talk...
bobs409, welcome to the world of driving a real truck, my friend! Back in the day, that was all they had; wide ratio or automatic. I've driven these trucks with the granny gear transmissions for years. It does take an adjustment, but it's really not that bad. The GOOD thing about putting one of these behind a V-8 is that you CAN lug 'em quite a bit, and wrap 'em out when you want to. I can run 3rd from about 8 MPH to around 65 if I really tach it out. I can run 4th from 20 to ??? Just drive it more and you will get the hang of it and realize that it's really not all that bad.
Also, don't get your hopes up with swapping out gears in that rear end. All they have is 4.10 or 4.56. If you want a really great setup, save your pennies and add a Gear Vendors! You get 7 forward gears (you can't split 1st). You get O/D and a whole bunch of middle gears. But the whole shootin' match will set you back around $3500. |
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#4 |
Registered User
Join Date: Feb 2003
Location: The Rubber City
Posts: 5,498
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Re: 4 speed w/granny gear...lets talk...
I agree, since it is a wide ratio truck trans it is sometimes undesirable. I dd'ed my GMC for a year and a half before the rockwell exploded, and it came to be second nature. However, I did stumble across a big New Process 542GL for dirt cheap, so I picked it up. It is from a Chevy school bus chassis, so it will bolt to any chevy engine. It is basically the same as the SM465, with the addition of an extra gear, first is still granny low, and 5th is still direct...should be a little better to drive on the road. The only downside is, this tranny is HUGE!. It also has a 13" clutch. Oh, and it is 2wd...so I am also going to swap in a divorced t-case. Shift pattern is in my avatar.
here are some pics...http://s14.photobucket.com/albums/a3...ik/NP542%20GL/ for reference... SM465 ratios: 1st- 6.55 2nd- 3.58 3rd- 1.57 4th- 1.0 NP542GL: 1st- 7.33 2nd- 3.96 3rd- 2.19 4th- 1.76 5th- 1.0
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1969 GMC K2500 ![]() 1996 Honda Accord 2007 Kawasaki KLR 650 Last edited by 1969 GMC; 05-14-2009 at 09:17 PM. |
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#5 |
Senior Member
![]() Join Date: Mar 2005
Location: weatherford,texas
Posts: 1,003
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Re: 4 speed w/granny gear...lets talk...
i have a sm465 in my '67 with 3.07 gears. there is a jump between 3 & 4 but not that bad if you twist it up in 2nd. with the higher gear ratio i can get more mph in second before i go to third and it's not that noticible to me but i have driving it that way for 15+yrs. they are tough tranny's, it will be hard to tear one up........but it has been done!!
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#6 |
Registered User
Join Date: Apr 2007
Location: Kalamazoo, Michigan, USA
Posts: 538
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Re: 4 speed w/granny gear...lets talk...
I have the sm465 in my truck and kind of like it. It's not all that bad once you get used to it. Are there better geared tranys out there? Yes, but this one will likely out last them all.
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1970 K20, 350--- SOLD 05 silverado extended cab short box- duramax Jeep wrangler unlimited |
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#7 |
Junior Member
Join Date: Dec 2006
Location: Southeast Missouri
Posts: 2,436
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Re: 4 speed w/granny gear...lets talk...
I have had 3 trucks with the 4 speed granny transmission and liked driving them all. Of course I use my trucks to work with. The first one I had was a '72 GMC that I used to pull boats up to 26 ft and travel trailers about the same length in Northern California. I had that one for I guess 20 years or so.
The two I have now are a '67 swb stepper and a '71 lwb stepper. The '67 has a l6 and the '71 has a 350 V-8. For the way I drive and use the trucks the transmissions work out great. Now my son says he would not have a truck with the old granny 4 speed and likes the three speed or automatics better. I guess at present he has 3 running trucks. I think it just depends on what you use the truck for and the kind of driving you do. Danny
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'67 Chevy C-20 short stepper - build complete, 454/SM-465. '75 C-30 Single Cab DRW-350 small block/NP-435. '77 GMC-6500 Dump Truck, 427 Tall Deck. '92 GMC K-3500 Duallie, 454/4L80E. |
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#8 |
Registered User
Join Date: Feb 2009
Location: Southern Oregon
Posts: 1,352
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Re: 4 speed w/granny gear...lets talk...
I too am new to the granny 4 speed. I have the sm465 in my '67 suburban. I really disliked it in the beginning but its growing on me. The truck has a 283 so it really likes to wind out in 2nd before I grab 3rd. I'm going to be towing a 3000 pound trailer over the Cascades memorial day weekend so I guess we'll see how high she'll wind in 3rd.
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#9 |
1969 Custom 30 wrecker
Join Date: Sep 2001
Location: Pottsville, Pa
Posts: 2,611
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Re: 4 speed w/granny gear...lets talk...
Thanks guys. I don't know about towing anything with this. Maybe if it's all down hill or if I stay in 2nd!
![]() I guess I'll have to get some more "seat time". Maybe it will grow on me. I used to work at a garage back in the late 80's and we had a 79 Chevy wrecker I drove that had the 4 speed trans. I know for a fact it wasn't like this one. 1st was still a useless stump puller but the other gears seemed more appropriately spaced. With a car on the back, I'd easily pull out in 2nd, not have to race it up to hit 3rd and no big jump to 4th. That trans I liked alot. Must have been a different ratio set up? Anyway, the truck is fun to drive with the manual steering and that 4 speed. LOL ![]()
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Bob 63 Impala 283/PG/3.36 (under restoration) 66 Impala 327/PG/3.36 66 Chevelle SS 409/M22/3.55 69 Chevelle 307/PG/3.08 (future restoration) 69 C10 short stepside 454/TH350/3.73 69 Custom 30 tow truck 350/4 spd/4.10 (resto done, CRUISIN TIME!) 71 Cheyenne 20 fleetside 350/4 spd/4.10 71 Chevelle 6/PG/3.08 72 Chevelle 454/M21/4.10 |
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#10 |
chevellelover
Join Date: Nov 2008
Location: albuquqerque new mexico
Posts: 88
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Re: 4 speed w/granny gear...lets talk...
I have the granny 4 speed in mine and if i want to get any power in 3rd or 4th i have to wind it up real high but i usually have to kinda bog up hill in 4th I havent found a way around it. But if you are getting after it 3rd usually nice a nice pull because it is so long.
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1978 Trans Am 400/4speed Year One Snowflakes 1980 c10 shortbed 1999 Suburban 5/7 drop US Mags Roadsters 1999 GMC Sierra Classic 4x4-MINT 2015 Challenger Scat Pack 6.4 8 Speed |
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#11 |
1969 Custom 30 wrecker
Join Date: Sep 2001
Location: Pottsville, Pa
Posts: 2,611
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Major update: Turns out the vacuum advance was not working so the engine was not putting the power out it should have.
Now that it's been replaced and timing set correctly, the truck has alot of power and getting up the hills isn't so bad now. What a difference!!! ![]() I sure am loving it now. Manual steering & 4 speed, I know I'm driving a REAL truck. lol So, now I need to know how to get about 20 MPG around town with it? ![]() Thanks guys, Bob
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Bob 63 Impala 283/PG/3.36 (under restoration) 66 Impala 327/PG/3.36 66 Chevelle SS 409/M22/3.55 69 Chevelle 307/PG/3.08 (future restoration) 69 C10 short stepside 454/TH350/3.73 69 Custom 30 tow truck 350/4 spd/4.10 (resto done, CRUISIN TIME!) 71 Cheyenne 20 fleetside 350/4 spd/4.10 71 Chevelle 6/PG/3.08 72 Chevelle 454/M21/4.10 |
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#12 |
Registered User
Join Date: Dec 2006
Location: Porter Ranch, CA
Posts: 978
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Re: 4 speed w/granny gear...lets talk...
Tow it with a Prius?
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#13 |
Registered User
Join Date: Feb 2007
Location: Cali Central Coast
Posts: 5,191
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Re: 4 speed w/granny gear...lets talk...
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'67 SWB Fleetside ZZ4/350/Tremec 5-speed/4link/Scott's IFS - and fun as heck! SOLD ![]() Click here to support the board Philippians 4: 6-7 |
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#14 |
Rollin Coal
Join Date: May 2009
Location: Winnebago Illinios
Posts: 131
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Re: 4 speed w/granny gear...lets talk...
what i love about my 465 with 4.57 rear ratio is that i never have to shift once im in the high hole. around any corner i want
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I have three letters to all these import guys: God-Made-Chevy 04 GMC Sierra 2500HD Duramax ![]() 1972 Chevrolet C-30 Dually Pickup stock? 350 SM465 four speed ![]() 1977 GMC K-35, TH-400, 4X4 450 horse 454(dad's) ![]() 1993 Dodge cummins 5-speed DEAD!! ![]() |
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#15 |
Senior Member
![]() Join Date: Dec 2006
Location: Studio City, Calif.
Posts: 2,873
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Re: 4 speed w/granny gear...lets talk...
Some of these trucks were ordered with the New Process 435 4speed. It was perfect for camper carrying trucks since the granny low was just 4.56-1.
Then second is 2.28, third is 1.31,and 4th 1-1. In some literature it is called "CR" or CLose Ratio. I've had both and preffer the close ratio one. If I was pulling a 31 foot Airstream up a hill and had to stop for traffic, I (and my clutch) would rather have the 465 granny with it's 6.55 low.
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'69 GMC C2500 Custom Camper, 8 1/2' bed, New GM 350, NP 435 Close Ratio 4spd. Trans., 3.73 Dana-60 open.Camper and Trailer wiring, PS, PB, AC, tach , three gas tanks, stereo speakers, 2nd owner, Work-Truck supreme. |
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#16 |
Registered User
Join Date: Dec 2006
Location: Porter Ranch, CA
Posts: 978
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Re: 4 speed w/granny gear...lets talk...
I have an NP435 in mine but it does not have the 4.56 granny gear. It has a 1st gear that is actually slightly lower than the 465 (6.68). I do know that certain model 435's (mainly newer ones) did have a 4.56 or 4.90 first gear and actually it makes it a much more usable gear. I had one in a Ford Diesel many years ago. The tranny was the only thing that DIDN'T fall apart on the truck!
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#17 |
Senior Member
Join Date: Jan 2005
Location: Loveland Co.
Posts: 3,098
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Re: 4 speed w/granny gear...lets talk...
My wife likes her SM465 so much she refuses to let me talk about swapping it out.
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Chris 74 Custom Deluxe SWB 350/350/3.73’s 99 2wd Silverado RCSB 5.3/4L60/3.90’s http://www.classictrucks.com/feature...short_bed.html |
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#18 |
Registered User
Join Date: Dec 1999
Location: Austin, TX, USA
Posts: 7,720
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Re: 4 speed w/granny gear...lets talk...
You solved your problem before I finished the post! I was going to say your torque output is the problem. All of the idiosyncrisies of the granny gear trans virtually disappear when you have a motor with a strong torque ouput at low RPM.
I used to have a 236 degree at .050 cam in my Jimmy and it made for a lousy drive. With the 206@.050 cam in it now, it is a joy to drive. If your engine is built to make peak power at around 4200-4500 rpm, the SM465, or SM420 for that matter, is nice. Build a 350, 383, or even better, a big block for it and the trans gets even better.
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44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax |
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#19 |
But Found Her 25yrs Later!
![]() Join Date: Oct 2010
Location: Oregon City, Oregon
Posts: 10,525
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Re: 4 speed w/granny gear...lets talk...
I can't remember what rearend I had in my 65, but I could put it in third, get the rpms up for the race, drop the clutch and run it all the way up to 70 without shifting any gears.
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I lost my 65 - Found it 25 years later: http://67-72chevytrucks.com/vboard/s...d.php?t=426650 66 C20 Service Truck: http://67-72chevytrucks.com/vboard/s...d.php?t=428035 Last edited by LostMy65; 01-26-2011 at 10:03 PM. |
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#20 |
Registered User
Join Date: Dec 2008
Location: Ashland, KY
Posts: 700
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Re: 4 speed w/granny gear...lets talk...
im glad you got it figured out! I LOVE SM465's! have one in my Jimmy w around 2.73s after tire height so with the granny gear i pull anything (including stumps) with little to no problem!
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68 C10 LWB 2/4 drop 406/th400/3.73posi 04 Silverado SS LQ9 6.0/4L65e/4.11posi AWD |
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#21 |
Vintage 4x4s
Join Date: Sep 2010
Location: Prior Lake, MN
Posts: 4,305
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Re: 4 speed w/granny gear...lets talk...
I'm assuming the 67 GMC 4 spd has to be the SM420? Looks like it has the following ratios:
SM465 SM420 1st- 6.55 7.06 2nd- 3.58 3.58 3rd- 1.57 1.72 4th- 1.0 1.0 Thoughts on the SM 420 behind the 305 V6 in the GMC I'm getting? Plan to restore it and use it to lug a few trailers around but no serious mileage at all. With the torque of the big block V6 it should work pretty good with wide ratio?
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67 GMC K1500 Custom- 305V6 SM420, PTO, Ram Assist, yellow (the outcast) (project period correct upgrades) 67 GMC C2500 351V6 TH400, AC, PS, PB (can't decide what to do with. Update, decided to keep and will restore ![]() 86 CHV K30 502 th400, apple red NEW 71 CHV K20 350 SM465, ochre (saved work truck) 71 CHV K20 292 SM465, white, tach, PTO, (future project) 72 CHV K20 350 350th, medium blue (project stocker) 01 CHV K2500hd crew, indigo blue ^3 dont run and the others don't see winter either '86 K30 Cummins "Fireside" thread: http://67-72chevytrucks.com/vboard/s...d.php?t=649649 '71 K20 "get driveable" thread: http://67-72chevytrucks.com/vboard/s...d.php?t=590642 '72 K20 Build Thread: http://67-72chevytrucks.com/vboard/s...=493477&page=6 Last edited by Vintage Windmills; 01-26-2011 at 11:12 PM. |
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#22 |
Registered User
Join Date: Dec 2009
Location: Ste. Genevieve, MO
Posts: 526
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Re: 4 speed w/granny gear...lets talk...
You gotta love that granny low, trust me when you get into a situation where theres a kid in a 98 f150 and hes saying your truck doesnt have any balls.....trust me it all pays of in the end.
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#23 | |
But Found Her 25yrs Later!
![]() Join Date: Oct 2010
Location: Oregon City, Oregon
Posts: 10,525
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Re: 4 speed w/granny gear...lets talk...
Quote:
It looks as though the SM420 has a wider gap between 3rd and 4th.
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I lost my 65 - Found it 25 years later: http://67-72chevytrucks.com/vboard/s...d.php?t=426650 66 C20 Service Truck: http://67-72chevytrucks.com/vboard/s...d.php?t=428035 |
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#24 |
Registered User
Join Date: Dec 2009
Location: Ste. Genevieve, MO
Posts: 526
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Re: 4 speed w/granny gear...lets talk...
Lol found the vid of that truck pull...sorry bout the quality....
250 inline 4 speed granny low 4.57 rear end gives an a** whoopin ![]() |
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#25 |
Just Not Low Enough!
Join Date: Mar 2009
Location: Phoenix, AZ
Posts: 525
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Re: 4 speed w/granny gear...lets talk...
i love my 465, course its backed by a 400hp+ 327
![]() i havent used first gear since the day after i bought the truck.
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NEED ELECTRICAL HELP? ASK ME! 67-72 Full Wiring Diagrams Lots Of Info, TAKE A LOOK 1967 Chevy C-10 Shortbox Bagged 327 4spd ![]() Previous: 1971 Chevy C-10 Short Sep I6 Auto (Traded) 1973 Chevy C-20 *THE REDNECK BATTLE TRUCK* 2001 Chevy Silverado 2Dr 5.3L Shortbox. R.I.P. 1969 Volkswagen Bug This is my first meeting, I have a horsepower problem. |
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