1972 pickup screams on the highway

[NYC-10]

just picked up a 1972 pickup with a 350/350 w/3.73 gears-on the highway it screams at 60-what are my options?- the previous owner gave me the original 3.07 gears.-I could put them back in or I found a 700r4 already rebuilt .It was a 4x4 tranny,could I use it in my 2x4?What is involved in putting in this tranny-what would you do?

[droppedgmc]

I'd go with a 700r4. i belive all you need is a tail cone for the trans, make sure it is the same length and will mount to the cross member

[red71cheyenne]

I have 3.73's with a 700r4 and it still screams on the hiway. Get used to it. Unless you want to go back to the 3.07's, thats just the way its going to be. I have thought about going to a 3.54 ratio if it can be gotten for this carrier, but haven't pursued it very far.

[Boog]

Your easiest fix is to reinstall the 3.07 rear end. That will put it back to where it originally was. It's a good all around gear. Or put in the 700R4 but it isn't just a bolt in. The TV cable has to be adjusted correctly or the trans won't last long. And depending on the trans it may not have cable drive for the speedometer. Then there is the lockup converter vacumn and electrical to wire in.

Red71. There is obviously something wrong with your setup if it's "screaming" with that combo. Use this online calculator to see what your combo should be turning. www.richmondgear.com street calculators . It lets you change the tire diameter, gear ratio and trans or OD trans to see what rpm the engine will turn at a certain speed. There are other online calculators but this is the one I use.

[Andy4639]

If you go with the 700-R4 trans mission you will more than likey have to cut the drive shaft also to fit for the longer tail shaft of the transmission.
I have the 700-R4 and 4:10 gears and it does fine out on the interstate. I have the lock up torque convert to.

[red71cheyenne]

I guess maybe I don't understand what he means by screaming. My RPM's are around 2000-2500 around 60-65 MPH. My rearend has always been noisy though. Didn't matter if it had the 350 in it or the 700R4. May just be my rearend is noisy!

[chevy72blu]

Im confused as to why I see so many threads of people complaining with that drive train. Assuming you arent rolling around on 20" tall tires or something, 60 MPH with 3.73 isnt doing any harm to your drive train. Of course, it will wear slightly faster, but not so much so to be a concern warranting an expensive trans swap IMO. I drove 3.73's with a 28" tall tire and a TH350 on the freeway daily for a couple of years, just keeping an eye on my tach.

Not trying to start a flame or anything of the sort- and of course, do what YOU want with YOUR truck. Im just saying that your current setup is alright.

The 3.07 swap sounds like a good idea if you already have the gears. It can be a little tricky if you have never done one before, though- and I suggest investing in some quality measurement tools. You will appreciate the 3.07's on the free way, but will miss the 3.73's leaving stoplights.

If you do mostly city driving in it, gas mileage will likely decrease with the 3.07's as it will take more throttle to accelerate from a stop. If freeway driving is going to be frequent, the 3.07s will obviously do better on gas. Just some food for thought.

If the actual motor whine is bothering you while driving, search around the forum for one of the many sound deadening threads. The stuff really does make an enormous difference.

chevy72blu

[Boog]

Red 71. Oh I see what you are talking about now. Your rpms are ok but it's the rear end that's screaming. It has a whiny rear end. Look into a new gear set. Oh and the difference between the 3.73 and a 3.54 is only around a hundred rpm.

[Cannon007]

cheapest thing would be to put back the 3.07's, but if u still want that low end pull off the line and like the low rpm on the highway, then you could get a bigger torq converter. If you haul a lot though I would stick with the 3.73's and look into an overdrive...

If you have the money to spend, then I would either do a built 700R4 overdrive or get a 5/6 speed conversion which is more money and work but really cool to have then you could run 3.73 gears or more and have it all.

[special-K]

We drive 90 mph these days with o/d,that`s the problem.Just roll that thing around 65 and enjoy.I scream my trucks when I feel like it,but slowing down these days.I ran my truck with 4.10s to Myrtle Beach from MD 75-80 all the way down I-95.It seemed very happy and I love that sound.I think alot of you only know riding with o/d.Other than fuel consumption,it`s not a problem.These trucks have been screamin`for over 30 years.

Bryan,I think doing an o/d will add value to your truck since that`s what people want these days.Keep the 3.73s and keep some grunt,yet get the final drive you want.I wouldn`t want 3.08s and o/d.The later 3.42s are as high as I`d want to gear a truck with o/d.Swapping the rear would be an easy quick fix.

[NYC-10]

thanks for all the input-I don't know if I could handle going 65,I usually cruise at 75.I don't mind the motor noise,I just don't want to beat on the truck

[streetstar]

Your not gonna hurt that motor at 65 mph -- it should be good for steady state cruising up to 3500 or 4000 rpm if needed (not recommended all the time tho)

Just get some quieter mufflers, a tach so you really know what its doing, and some Dynamat -- or Brown sugar - or whatever that stuff is called (help me out guys)

[PanelDeland]

I think Special hit the nail on the head.Most of us are used to engines turning about 2000rpm's at 70-75 on the highway and it being quiet in the vehicle.In 1967-1972 that ain't so.The trucks were workhorses and just starting to be upgraded with PS.PB.A/C and other comfort items.Sound deadening was a high end car thing and wasn't as refined as today.You are probably hearing the normal noise a truck of this era makes and thinking it's way too loud compared to (insert your past DD here).

[NYC-10]

my last truck was a 72 Blazer with the same gears,the tires were a little bigger so the rpm,s was not as high-I am used to road noise

[Premium72]

put what ever tranny you want in it. with low a$$ gears in the rear. itll always ride like that. change those babys out maybe sumthn higher that the original gears, youll lose some get up an go but gain some top speed and will be a smoooooooooooooooooooooooooooooooooth ride!.

[Spray-Bomb]

Not that you needed more input, but here is mine... lol

I drove my 67 all the way to Norwood 7 back (350 with 400 trans & unknown gears) On the way up we cruised 65-70 (did fine)

On the way back I was pissed off & ready to get home, so I rolled up to 90 (but usually 80 @ about 3K)
My truck did fine, so I think that as long as you're not too worried about MPG & your engine is well tuned you should be fine

If it was me I'd leave it for a while, till I got the 700r4 in & then I'd decide if i wanted to change gears or not (3:42's are really good gears for 700r4's)

[ChevLoRay]

Yeah, we've gotten used to running at lower RPM's with the overdrive tranny's we have in our late-model's. Ain't the "scream" what we grew up hearing and then forgot about?? My youngest son, while riding in my '69, kept waiting and finally said, "When's it going to shift?" See? He grew up on O/D, not on 1:1 stuff.

I like my 3.08's and my TH400. If I had to use it for everyday commuting, I'd try for an O/D box. The 275-60's slow it down a hair, but I still like the "scream".

However, if it was a "whiny hiney", I'd be looking for a good rear end.

[swamp rat]

Originally Posted by brian gruber

just picked up a 1972 pickup with a 350/350 w/3.73 gears-on the highway it screams at 60-what are my options?- the previous owner gave me the original 3.07 gears.-I could put them back in or I found a 700r4 already rebuilt .It was a 4x4 tranny,could I use it in my 2x4?What is involved in putting in this tranny-what would you do?

Do you have a tach?? Just wondering what your rpm's are?

I have 3.73's and I'm pulling around 2800 which I thought was pretty good

[franks72]

I have 3.73s in my 72 . On the highway at 75mph (I think ,my speedo is not right) I'm at 3200 all the time with a 28 inch tall tire.If your motor is in good shape I don't see a problem..

[wibilly]

iv'e got 373s in my 69 with a sm465 and 31" tires i like the way she sounds at 7o mph through the glass pacsi think i'm gonna go to 3.08s to save a little fuel though. i have a 700r4 but i'm not willing to give up my 4 speed thats what makes it a truck

[screamin_c10]

Hence the name.