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oldironlindy

Making a 72 Pickup Faster

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I have an old 72 IH pickup with a 4 speed that I would like to be able to cruse down the freeway with but still be able to pull a trailer if needed. Anyone ever change the gears in the rear end or put a two speed rear end on a pickup ? I would like to keep it as stock looking as possible.

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need to know what gears. what engine. what size of tire. you told us its a 4spd.

so. couple of ways...get bigger tires

if the rear axle is a dana 44/60/70. dana 60 i doubt but i dont know the model of the truck. all dana axles have good aftermarket support so a ring and pinon swap isnt hard.

you also need a tach. many times the ih v8 engines sound like they are maxxed out but you arent even close to redline. also your sv8 likes to run near its rated redline. the sv8 ratings show continuios duty rpm's. not an actual redline.

if you have 4.10's and 31+ tires you can run freeway speeds.

adding a two speed wont increase your top speed usually as your high range will probably still be the same or even lower geared. two speeds give you extra gears between shifts to pick up the gaps in your trans. also most are geared to run large truck tires.

i say either swap to 3.73's and keep a small tire size or use 4.10's and run a 32/33 in tire

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Is this a problem with existing gearing being too high or too low? Assuming it is too tall as is?

The two speed sound good but as said, they are for big tires and lots of revs. Hi/lo ratios are around 7 and 9, and they are physically pretty big, even from a 1600 "small truck". I don't think there were any in the "pick up" class?

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Not that it helps, but a 2 speed rear end was available in a 1500/1510, which was a 1 1/2 ton "pickup."

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Ok so the two speed is out. It as a 3/4 ton 2 wheel drive with a V-8 I think its a 345. How do I tell which rear end is in it?

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best way to tell is order the line setting ticket from one of your light line dealers. or wisconsin historical. if its a 3/4 ton my guess would be a dana 60 or an IHC corperate axle. these are 8 lug models. the axle ratio may be on the axle tag still. my guess would be 4.10's your 345 has a continuios duty rpm of 3800rpm. that where it makes its power. run the damn thing at 3400rpm all day and it will thank you. my 304 in my terra rarely sees rpm's under 3600

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IHRunner is right on his high RPMs comments.

When we bought our '63 1600 with a V-304-----our local dealer truck specialists told us to "keep it wound up------and don't lug it at highway speeds".

Re: obtaining higher speeds

Back in the 80s------there was an auxillary overdrive box advertised for installation on p-ups. It mounted into the drive line behind the transmission------and worked similar to a 2 speed axle; but gave you an unknown overdrive ratio.

Seems like they were approx $800-----don't know anything about them------never saw one installed-----and don't remember the brand.

DD

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I had IH light duty vehicles for many years and never had any issues of keeping up with traffic.

The big one was a 70 1200D 4X4, V345, 3.73 Dana 60, T419 4 speed, Rockwell/warner (not a DANA) TC, 7.50X16 tires stock.

Went to 12X16.5 tires on 9.25 wheels after initial tires wore out.

It cruised at 65 - 70.

Got rid of it in 73 no real issue at all with the vehicle.

This was not a junk vehicle it had 43 miles when I got it.

REGRET GETTING RID OF IT TO THIS DAY!!

69 Travelal 2wd, got in 75 with 35000 miles on it.

V304, T98A1, Dana 44 RE 3.54 gears.

700X15 tires stock

Went to 9X15 after initial tires wore out.

Converted it to 4X4 in 82 using all stock junkyard/ rebuilt parts

Dana 44 3.53 front axle.

NP 205 TC

12R15 tires on 10" rims.

I liked the V304 better than the V345.

The V304 loved to be run at 3,500 in 3rd pulling hills.

I kept the 69 until the body rusted away in 89.

Never any mechanical issues with the drive train.

Either vehicle was in good shape and not mechanically junk.

Either vehicle kept up will the freeway traffic.

I was in NAPA county California, with many hills in all directions.

We would take a trip to Lake Tahoe monthly during the summer. That's sea level to 6000' and back in 225 miles one way

30" tires and 3.54-3.73 gears, 4 speed manual, would keep up with traffic with the v266,v304,v345 in any LD vehicle the engines were installed in.

Before you start worrying about gears, I would make sure the engine is running like an IH SV is supposed to run.

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For making a SV 345 a little quicker, I have had luck with just a RV cam, electronic ignition with new coil, coil core ignition wires, and look into a 4 barrel carb setup if yours is not already equipped. I definitely agree about installing a tach. Mine at 2800 on the highway sounds like a freight train but thats still 1k RPM from continuous duty redline.

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"Gear Vendors" was one of the overdrive manufacturer's. a buddy of mine's Dad put one in a ford that went between the bel housing, and the transmission.

I used to have a '74 scout, 304 auto, 4x4, 373 gears. Never had a tach but I never had trouble keeping up with traffic. I don't remember going over 80 mph very often.

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http://m.youtube.com/watch?v=ytQyTb0kU7Y&feature=c4-feed-u

made for OIL. 2nd gear onto highway 50. upshift to third gear. hold at 35mph. accelerate to 45mph and shift into 4th. at 45mph in 3rd im running 3500rpm's not even close to my 304's redline. vaccum advance fell off leaving the resturant so thats why it sounds a bit rough. but you can hear. at only 3500rpm it sounds like its ready to detonate but it isnt

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http://m.youtube.com/watch?v=ytQyTb0kU7Y&feature=c4-feed-u

made for OIL. 2nd gear onto highway 50. upshift to third gear. hold at 35mph. accelerate to 45mph and shift into 4th. at 45mph in 3rd im running 3500rpm's not even close to my 304's redline. vaccum advance fell off leaving the resturant so thats why it sounds a bit rough. but you can hear. at only 3500rpm it sounds like its ready to detonate but it isnt

That was interesting, and very familiar. Dash looks just like my 72 Scout II. Mine always sounded fairly comfortable at 60 mph cruising the highway and got decent gas mileage too. No idea of the rpm but I'd guess a little under 3000 .

My thought on the subject is even if the 304 can run comfortably at 3800, it shouldn't have to. Most of today's vehicles cruise comfortably in overdrive at 2000 rpm or less even with smaller engines. I'd like to see the 304 with a gear ratio or overdrive that would allow the engine rpms to stay around 2000 rpm even at 65 mph.

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no can do hoss. i tow alot with that 304. i have the bw t19 wide. if i dont keep my rpm's up im not gonna make it up dem mountains and hills. going to rmihr as long as people let me do 75 my rpms were high enough to maintain some of those hills at 3200. but if i had to do 60-65 and hit a hill id be forced to downshift into 3rd and drive 45-50 mph. for cruisin 2000rpm would be nice. but im not sure if the 304 is even making peak torque at that point. id be dismally underpowered for towing. IHPA sells an adapter kit to mate the gm automatics to a scout. the od auto would help. but towing and in large applications the ih sv8 needs and likes to be run at higher rpms to make enough power.

your scout looks really nice. reminds me of my pumpkin....only you have the other half of your engine under there

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I would think somebody here on the forum has copy of the RPM/torque curves on the 304---345s----would be interesting to see where optimum torque range is.

I refer back to what our local IH truck rep (Pops Imbler with Delta Implement Co.----Greenville, Ms) told my dad and myself about our 304; --------"keep it wound up-----don't lug it". We never had a tach on the 1600.

Lots of difference in pulling a load-----and running empty. The newer automatics run up to 6 shifts----but they all recommend clicking overdrive off when towing. Our Expedition runs freeway speeds @ 1800----2000rpm-------but starts downshifting on the slightest hill climb.

One thing that makes the older engines sound fast is the "fixed speed fan"------no clutch.

Interesting thread going here.

DD

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post-68134-0-20188600-1384277140_thumb.j

posted this before. 392 dyno test. broad flat torque band.

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I do have some experience with a 5 speed OD manual in a 72 1200D 4x4.

My buddy had this rig, I was around it for most of its life and drove it on several occasions and made several trips in it.

This truck was a V345 4x4 with a 3.73 RE and the optional 5 speed OD spicer. Do not remember the od ratio but believe it to be about .75.

The truck had a medium sized cab over camper mounted.

The OD was holding gear, meaning that you accelerate to the speed you want to run at and then stick it in over drive to hold that speed.

Was fine on relatively flat ground unloaded but hills and loads the OD was not of much use.

On a trip from Napa, Ca to Klamath Falls Or, rolling hills all the way, we were constantly shifting.

When I was driving I just left it in 4.

Across Texas on relatively flat ground it was a useful gear and would get over 1-2 mpg more in mileage when using OD.

The 5 speed was an expensive option that I never thought paid for its self.

BUT it did give it an extra gear to use and low was a little deeper than most lT 4 speeds.

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Yes, definitely every owner/driver has to know the type of driving he is building the truck for. Obviously cruising empty down the highway , especially in Sask., there is only wind resistance to deal with. My S Blazer with the 4.3 V6 can maintain highway limits easily at 1900 rpm in overdrive. Long hills are a different story and it shifts down pretty quick.

My Loadstar 304 runs just fine at low rpm in high gear as long as it is empty. I have cruised the small town streets in 3rd gear without breaking the speed limits. But load it up with grain grossing +25,000 pounds and yes, it needs plenty of rpm to build enough speed to shift to the next gear up. Times like that I'd like to have a 392 up front. But running empty I'd like to have an overdrive so that 304 didn't have to spin so fast just to hit 55 mph.

Here is a video I shot a while back showing it running from 15 to 40 mph in 4th gear, high axle. No shifting. That 304 just runs smooth as can be from idle on up although its a little hard to hear in the video. Running with an empty truck of course.

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