Help out a new guy
Senior User
Joined: Jul 2012
Posts: 150
Likes: 2
From: Kansas City, MO
Thanks for the tips. I will check the tach to see if it is set right. I had not thought of that. Then next time it is warm enough here to drive her I will manually shift and see if it seems to be going into third. I will also verify the rear end gear ratio while I am at it.
If it would turn out to be the tranny not going into third what would the likely causes be? The transmission has less than 350 miles on it.
Thanks
Alan
If it would turn out to be the tranny not going into third what would the likely causes be? The transmission has less than 350 miles on it.
Thanks
Alan
Tuned
Joined: Jul 2012
Posts: 294
Likes: 4
From: Pensacola, FL
Guys,
Here's a online calculator where you can put in wheel size and rear end ratio and rpm and get estimated speed. Might help you figure out what rear end ratio you want to run.
Stan Weiss' - Automotive Performance Software / Interactive JavaScript to Calculate Speed(MPH) for given RPM, Rear Gear Ratio and Trans Gear Ratio
Here's a online calculator where you can put in wheel size and rear end ratio and rpm and get estimated speed. Might help you figure out what rear end ratio you want to run.
Stan Weiss' - Automotive Performance Software / Interactive JavaScript to Calculate Speed(MPH) for given RPM, Rear Gear Ratio and Trans Gear Ratio
Fleet Owner
Joined: Jul 2004
Posts: 27,294
Likes: 1,055
From: NM
A bad vacuum modulator will delay shifts, but I don't think it will completely prevent them. But it's the first thing I'd check. Make sure it's getting vacuum.
Post Fiend
Joined: Feb 2001
Posts: 6,328
Likes: 124
From: Iowa
Vacuum modulators are also adjustable. At least mine is. You can tighten or loosen the screw which is inside the vacuum port/hose nipple. It doesn't make a drastic difference in shift point in my experience though.
We also have a kickdown linkage in the mix here too right?
We also have a kickdown linkage in the mix here too right?
Fleet Mechanic
Joined: Mar 2005
Posts: 1,511
Likes: 1
From: peyton, colorado
You really need to know where you're starting from, so start with determining your gear ratio. I pull the cover and count teeth, but Ross's method works too. Either way you've got to get the axle off the ground so you can turn things. Your C4 will have a 1 to 1 top gear, so the only variables will be the rear tire height and axle ratio. Make sure you really have a low axle ratio and the engine is really taching high. I bought a jeep once from a guy who hated it on the highway. Said he couldn't run faster than about 50-55 because of high engine rpm. After finding the gear etc to be OK, I replaced the giant 7 blade solid fan with a clutch fan. He was mistaking fan noise for high engine rpm.
Postmaster
Joined: Apr 2004
Posts: 3,005
Likes: 2
From: Santa Clarita
If your having issues with the transmission not shifting into 3rd, I would try and see if the transmission will shift using the manual method. NOT in drive, but go from L, 2nd, 3rd. That will tell you if you have vacuum issues or not. If it's shifting fine manually, and not in D, the modulator or a low vacuum from the manifold may the be problem. If it's not shift manually to 3rd, it could be a valve body or the servo which I would recommend having a tranny shop look at. BTW- if your messing with the vacuum modulator, your not suppose to adjust it either way more than a 1/4 turn, or you'll end up buying a new modulator for sure.
Post Fiend
Joined: Jun 2003
Posts: 8,209
Likes: 12
From: Black Hills of SD
My book doesn't break down the models or even give the codes for the rear ratios but my 56 F250 has 4.86 and very likely yours does too if they are original. As mentioned, it's easy to find out.
But with stock 31-32 inch tires, I would stay in the 3.73 range unless you want a real dog. 3.54 maybe but a 3.00 or 3.25 may find the engine below the power band and lugging too much. Do the math and find a gear ratio that matches the tire diameter to keep the cruising rpm in the 2200-2800 rpm range. It's a heavy pickup and any cruising rpm much less than 2200 will find you mashed to the floor on hills just to keep up cruising speed.
Just my 2 cents. Other opinions may vary.
But with stock 31-32 inch tires, I would stay in the 3.73 range unless you want a real dog. 3.54 maybe but a 3.00 or 3.25 may find the engine below the power band and lugging too much. Do the math and find a gear ratio that matches the tire diameter to keep the cruising rpm in the 2200-2800 rpm range. It's a heavy pickup and any cruising rpm much less than 2200 will find you mashed to the floor on hills just to keep up cruising speed.
Just my 2 cents. Other opinions may vary.
Elder User
Joined: Jun 2010
Posts: 934
Likes: 2
From: Sterling, Virginia
I also have a 289 with a c4, but I have a Ford 9" with 2.75 gears. It's the original drivetrain from a 68 Farilane. When I'm going about 65 to 70 mph, my Moon tach reads about 2300 to 2400. So unless it's not shifting into 3rd I say change the rear. It's may be a pressure problem in your tranny preventing it from shifting. My 2cts. Good luck with it.
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Postmaster
Joined: Apr 2004
Posts: 3,005
Likes: 2
From: Santa Clarita
The reason I'm recommending 3.00 or 3.25 is the fact that I'm running a 289 with a C4 as well. I have a 9 inch Ford with 3.50 gears. I'm running 28" tall tires on the rear. At 60 mph, I'm taching at 2800 rpm. The engine is screaming. I had 2.75's in it and it was no where near a dog, but didn't have the acceleration around town. Highway? 60mph, and taching a comfortable 2100 rpm. No need to stay in the slow lane and have people extending their finger at me. I prefer the 3.50's because most of my driving is around town and not long distance highway driving. If I do hit the highway, I stay around 55mph and in the slow lane with the big trucks.
Senior User
Joined: Jul 2012
Posts: 150
Likes: 2
From: Kansas City, MO
I also have a 289 with a c4, but I have a Ford 9" with 2.75 gears. It's the original drivetrain from a 68 Farilane. When I'm going about 65 to 70 mph, my Moon tach reads about 2300 to 2400. So unless it's not shifting into 3rd I say change the rear. It's may be a pressure problem in your tranny preventing it from shifting. My 2cts. Good luck with it.
I hope it is not a problem with the transmission but the way things have been going it would not surprise me. One of the reasons I bought the truck was because it had rebuilt 289 and new Sizzler C4 (less than 300 miles on both). However the truck had been sitting for around two years after the PO had installed them so nothing would be covered by the original warranties. I already had to replace the lifters on the 289, I hope the tranny does not also need work.
Thread Starter
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Junior User
Joined: Jan 2013
Posts: 76
Likes: 1
Might be able to go to a 3.00 or 3.25 with the 9" rear, but the highest I've been able to find for a Dana 60 is 3.54. I've heard rumors of something like a 3.33, but no luck finding one. At any rate, I think the 3.54 is gonna do the trick. Thanks for the help guys, I'll report back when I've got it sorted. Feel free to do the same, oldwi. Seems this thread has enough info pertinent to both.
Senior User
Joined: Jul 2012
Posts: 150
Likes: 2
From: Kansas City, MO
Might be able to go to a 3.00 or 3.25 with the 9" rear, but the highest I've been able to find for a Dana 60 is 3.54. I've heard rumors of something like a 3.33, but no luck finding one. At any rate, I think the 3.54 is gonna do the trick. Thanks for the help guys, I'll report back when I've got it sorted. Feel free to do the same, oldwi. Seems this thread has enough info pertinent to both.
Post Fiend
Joined: Feb 2001
Posts: 6,328
Likes: 124
From: Iowa
Might be able to go to a 3.00 or 3.25 with the 9" rear, but the highest I've been able to find for a Dana 60 is 3.54. I've heard rumors of something like a 3.33, but no luck finding one. At any rate, I think the 3.54 is gonna do the trick. Thanks for the help guys, I'll report back when I've got it sorted. Feel free to do the same, oldwi. Seems this thread has enough info pertinent to both.
Fleet Mechanic
Joined: Aug 2010
Posts: 1,994
Likes: 3
From: Morgan Hill, CA
Coyote....some of those Dana 60's came out of trucks with really low gears. An AOD probably wouldn't fix the problem. You should see about getting a new set of gears installed. With a small block and a C4, you'd probably be pretty happy with anything around 3.25:1, but your gear selection does depend on what your tire size is.
Dan
Cargo Master
Joined: Aug 2007
Posts: 2,560
Likes: 69
From: New Zealand
Might be able to go to a 3.00 or 3.25 with the 9" rear, but the highest I've been able to find for a Dana 60 is 3.54. I've heard rumors of something like a 3.33, but no luck finding one. At any rate, I think the 3.54 is gonna do the trick. Thanks for the help guys, I'll report back when I've got it sorted. Feel free to do the same, oldwi. Seems this thread has enough info pertinent to both.
The 61 had differences (the details of which I forget) that allowed higher ratios than the 60 could accomodate.