Three speed Saginaw top speed ?

[kcfirstbuild]

So I finally drove my 68 for the first time. Never once have I been through all three speeds. On my way home from the alignment shop. I was up to fifty and it sounded like I was really pushing the Saginaw. My combo is the original 307 rebuilt, three on the tree, and a Saginaw.

Hope this is normal. I know everything on this truck is geared low.
Posted via Mobile Device

[In The Ten Ring]

My truck has a 3 speed on column, 4:11 rear end. It'll do 65 mph but you can watch the gas guage slowly go down. (I kid you not).

It's happiest speed is probably around 45.

[kcfirstbuild]

Is your Saginaw loud at that speed ?
Posted via Mobile Device

[67_C-30]

Originally Posted by kcfirstbuild

So I finally drove my 68 for the first time. Never once have I been through all three speeds. On my way home from the alignment shop. I was up to fifty and it sounded like I was really pushing the Saginaw. My combo is the original 307 rebuilt, three on the tree, and a Saginaw.

Hope this is normal. I know everything on this truck is geared low.
Posted via Mobile Device

Yes, its normal. Modern OD vehicles make most older cars and trucks (unless they have ultra low 2.41 or 2.56 gears) seem like they are buzzing super high. People drove these things cross country like that when they were new.

[WIDESIDE72]

Any original equipment transmission in 67-72 trucks will be 1:1 in third gear, whether its an 4 spd SM420, 3 spd saginaw, TH400 or TH350. The only way to get your engine spinning slower is to swap to a numerically lower rear gear ratio or swap in an overdrive of some sort; 700r4, 2004r, T56, NV3500/ 4500, gear vendors etc.

[71meangreenc10]

I still have the Saginaw in my 71 SWB. When I had the 3.73 with the 283, I could burry the speedometer. Now, if you have 3.08's in the rear with that combo, it will be a slow journey....

Smitty

[nobolt]

my 72 was turning 3000RPM @ 60MPH. it is probably due to your rear end gearing.

[Keith Seymore]

Agee with all of the above: the final drive ratio in the Saginaw is 1:1 so you are not "buzzing the trans". It will go as fast as you want to go.

The sensation of buzzing the driveline is due to your rear axle ratio or lack of overdrive.

K

[cdowns]

Originally Posted by 71meangreenc10

I still have the Saginaw in my 71 SWB. When I had the 3.73 with the 283, I could burry the speedometer. Now, if you have 3.08's in the rear with that combo, it will be a slow journey....

Smitty

truck with a 308 has ALOT higher topspeed than one with a 373

[19673ontree]

Sainaw three speeds are just like a 250 six cylinder engine they are bullet proof mine had 3.73 in it and was happy at 45mph I put 3.08's in it now I can run 70 I am in pigeon forge right now drove it 3 hrs 70mph thursday !
Posted via Mobile Device

[71meangreenc10]

Originally Posted by cdowns

truck with a 308 has ALOT higher topspeed than one with a 373

Thats not the intent of the message, 3.08's will be slower to get to the top end with that set up he has. 3.08's and a saginaw is not preferred if you want to jump off the line with a quickness......

Smitty

[Tx Firefighter]

If the truck has some form of solid fan in it rather than a fan clutch, it will sound more frantic too. A solid or flex fan spinning fast sounds like an extra 1000 rpm to your ear when going down the highway.
Posted via Mobile Device

[lil hoodlum]

My truck has the 3 speed Saginaw and I routinely take it up to 80 MPH. It seems to like it there but as in the ten ring mentioned, you can literally watch the gas gauge needle move.

Keith

[kcfirstbuild]

So it has nothing to do with my saginaw then i take it. Here is a pic of my of my Butt ! How do I tell if its a low gear one ?

[special-K]

1:1 final drive is what all vehicles have for top gear no matter what the transmission. Overdrive is a gear beyond final drive that reduces rotation to roughly .7:1.

[Boog]

Determining rear gear ratio is easy enough. Remove the diff cover and count the teeth of the ring gear and pinion gear to be exact or lift the rear end, turn a rear tire one revolution and count the times the driveshaft turns over. Right at 3 turns will be 3.08, 3 and 3/4 turns would be 3.73 and so on.

[capev86]

truck with a 308 has ALOT higher top speed than one with a 373

but around town performance will suffer. and towing will be all but impossible. i might use 3.08 gears behind a diesel, but a stouter rear gear plus overdrive is really the way to go. on my dad's 87 Suburban c1500 w 350 and 700r4, changing from 3.08 to 3.73 gears was night and day. before that the truck couldn't get out of it's own way. in o-d, we maybe lost 1mpg. the engine no longer working so hard at such a low rpm. a 3.42 rear from a 90's truck might be a better choice. his current 99 Burb C1500 has hit 22mpg with 3.42 gears.

on my 72 Suburban C20 307, 3 on the tree, i changed the rear gears out from 4.57 to 4.10. the 4.57 gears were so low that i barely used 2nd gear. now i can make full use of 1st and 2nd gear and it will still be stout enough for towing. i do shift into 3rd above 20mph under light throttle. i installed a Q-jet at the same time and the combo is perfect for around town and back country roads. a steady trip at 50mph has so far netted me a best of 16.5mpg.

even now the truck turns 3,000 rpm at 60, so i take my time on long highway trips. i have a spare (late 60's) Saginaw with the Borg Warner R-10 overdrive on the back. but i don't have the equipment to operate it and the trans supposedly needs a 1st gear synchro. but the effective ratio in o-d will be 2.87:1. that's 7% better than a 3.08 on the highway, but i won't have to sacrifice the off the line performance of those 4.10 gears.

[54belair]

Gear the truck for what youre going to use it for:

If you want a heavy pulling, heavy hauling truck--then stay with a 4.11 gear. If you do mostly town driving and no or little towing then a 3.73 will be perfect.
If you are building a cruiser and wont be towing and want good hiway speed cruising then go with the 3.08 (or even a lower numerical) gear.

As far as "performance" off the line---depending on yur engine, tires, etc, you can launch one of the trucks as well with a 3.08 as you can a 4.11.

Im using a car 4 speed and a 3.08 in mine (when it hits the road again) and I can guarantee that combo will smoke any tire I might run. In my other street machine (the 54 chevy hardtop) Im running a mild 350, a th350 and a 2.56 rear----it weighs as much as a short truck, and it will get it off the line and pulls like crazy in second.

Anyway, just saying,, make life cheap and simple----dont kill your wallet with a 4.11 when a 3.08 might do!!

[capev86]

if all you do is flat highway with no hills and never haul anything, then by all means get the 3.08 gears and be cheap about it. i would only use them in a car (better aerodynamics and shorter tires)....too soft in a truck even behind a 350. the 307 needs a little more rpm to work effectively anyway and that's what kcfirstbuild is running for an engine, not a 350 with a lot more torque to throw around.

also consider a better induction system to make the most of that little v8. it will help offset the softer gearing. the 2 barrel on my 72 Burb was the first thing to go, other than the points ignition (now has a petronix kit in the distributor).

[jocko]

back to the original question - no, what you are hearing is normal. truck WILL go fast, it's just not geared to go fast at a reasonable rpm. As mentioned above, what you choose should be dependent on what you want to do with the truck. From a mathematical standpoint, on any given engine, the top speed you CAN achieve will be higher with a lower numerical rear end ratio (i.e. higher gear). And, yes, it will be slower off the line with that lower numerical ratio compared to a higher one also - but it is not physically possible to achieve the same TOP speed with different rear end ratios. (i.e. just because you can get to 70 in your 3.08 AND your 3.73 setups only means you are not at the top speed for the engine, yet, but you are closer to it with the 3.73 while the 3.08 has a ways to go before the motor is wound out at its top rpm, that's all)

[kcfirstbuild]

Thanks for all the input. Some went over my head, but all in all from what you are saying is that the sound is normal and the speed is normal for the set up I have. Its just a sunday cruiser. The 307 was dynoed at 200 hp haha, but I wanted to keep everything original.

[sharkskinman]

65 step side 230/3.73 rear 60mph seems fine bout to install a tach
Will a Saginaw 3 speed be good?

It's stock now and takes off just fine but definitely seems lil a short 1st gear
Will the Saginaw work with 3 tree colomn?
Stock or Saginaw 3 better for later motor upgrade?
Seems I can look for an overdrive

[special-K]

Saginaws were stock in these trucks

[sharkskinman]

Can't get a picture ok the dark
Please post distinct pictures of the driver side of the trans'

I've been looking on Google and haven't found many clear ones
But seems mine is a Muncie?

[sharkskinman]

Looks like this without what looks like overdrive

http://img2.uploadhouse.com/fileuplo...b862fb0c79.jpg