The Stovebolt Site Forums The Shop Area Driveline Getting my 57 3100 up to speed.

Up to speed as in keeping up with others on the backroads and highways. What is the easiet, fool proof way to make my 57 get up to speeds of 70-80ph??? I have a 235 straight 6 and don't know what gearing ratio. All I know is that everything is stock. I would like to keep that way as well, if possible. Don't want to mess with changing out the whole rear axle and differential, maybe willing to change the transmission as long as it doesn't do away with the three on the tree that I love so much. Won't be doing any hauling or strenuous driving, just drive around town, ice cream runs, etc.

There are no easy transmission changes that keep the truck close to stock. They all require messing up the frame, pretty much.
Well an overdrive of the same vintage is about the only trans change that is acceptable. I think the easy thing to do is the rear end gear ratio. You probably have a 3.9 now.

With all due respect to Truckolet, I disagree. I think a 3sp/BW OD will work well for this application. I installed one in my 55.1 3100 which I believe has the same driveline. The only mods were
- change the side cover from the stock 3sp to the new one so the shift linkage would not have to change.
- add wiring to power the OD shift solenoid
These mods are completely reversible should I sell the truck to a purist

The result is that my 60 mph cruise rpm is now 2000, right at the torque peak of the stock 235. It's much more comfortable to drive due to the lowered sound level.

I don't spend much time at 70 due the the stock brakes and my conservative nature, but the truck easily gets there when necessary to pass someone.

regards,
Leon

I must add that i am trying to keep it fairly affordable. I've heard about changing out the ring and pinion to a 3.38:1??? Is that something simple as buying the ring and pinion and installing? No modifications to anything else?

the R&P change isn't 'simple' or necessarily 'affordable', normally you'd need an overhaul kit for the rear at the same time and it requires some skill to do the whole install, probably at least double the price of just swapping out the trans for the OD

Bill

???? I thought I said OD trans???? The main reason its not an easy deal, either, is where are they?????????
I want one, I've been looking for a long time. Since they are so difficult to come by that makes the ring and pinion an easy change.

IMO: They are not supposed to go 70-80. Nothing about it is made for 70-80 except the speedometer, with or without an OD. Who goes 80 miles an hour on an "ice cream run"? I would not go 70-80 in my TF's. Steering, brakes and other components not "robust "enough for that speed. No seat belts? Forgetaboutit. BTW: an overdrive transmission does not make you go faster.

I will be frequenting the freeway with posted speeds of 70. I wouldn't go that fast but hey a nice 60-65 cruise without my engine revving high would be nice don't you think? Plus I plan on upgrading to disc brakes up front and probably a 60/40 bench with seatbelts.

I've heard a lot about switching the ring and pinion to 3.38:1. Would that give me what I want?

I here a lot of people wanting higher speed rear ends. What is your complaint with your setup now? If it is noise I wonder if your valves are adjusted correctly?
Growing up my Dad put 300,000 miles on a 1960 Carryall with a 235 and 3.9 diff. same drive train as yours. The speed limits were 70 MPH. It seem to work fine for us.

The whole reason behind my post was to find out if something would fit my needs better. Not to be rude but others wants and needs are not the same as mine. I asked for advice on gearing and so far I have not had any straight answers. Yes I want the truck to go faster, yes I want it to be less noisy (due to high RPMs), and no I don't want to change the original drivetrain, just tweak the gearing to where I'd like them to be. So would a 3.38 be beneficial or not? Ultimately what are the pro's and con's of switching ring and pinion to this newer setup?

yes, the 3.38 gears would let you go faster at any given RPM, so probably you could go 60-70 with less engine noise, although you could add sound insulation a lot cheaper, and you could find an original 3 speed overdrive [still column shift] to accomplish the same thing, probably also cheaper, the rear gear swap would probably be a minimum of $500, some have spent $1,000

Bill

Thank you Red58. Exactly the answer I was looking for.

How fast does it go now? and does it feel comfortable? As in: not squirly. As Bill is advising, changing the guts (ring and pinion) of a rear end is NOT for the average guy. The kit IS expensive and you need experience and a dial gauge, a torque wrench and maybe a press. If you really, really think you need different gears, find a rear end and swap. That is easy(er). A 3.38 would give you what you want. (What do you want again?) You will sacrifice on the low end however. I think Truckolet and Dave are leaning toward what I'm saying also. If you think you might be a hot rod guy, get a V8. The perfect Chevy rear end for a balance of torque and speed is a 3.73. Many available. Gotta find one with nearly same width. Been there, done that, on TF.

What rear end swap would be best? What rear ends from other years for the same as the original rear end?

You were posting while I was editing, read again. Measure WMS to WMS,then measure 60's truck Diffs. Spring perch and shock mounting may need mod. 60"-62" probably works. Lots here and on the interweb about rear end dimensions and swaps.

First of all... These old girls will go straight down the road at 80 mph all day long. Please make sure the brakes are up to the challenge and the suspension is in proper spec.

3.38 gears will not drop rpms as much as an od transmission. The change from the stock 3.90 gears to 3.38 gears will give you about a 15% drop in rpms. The od swap will give you about 27% drop.

3.38 gears are not the only option. 1957-1959 gmc 1/2 ton trucks with the 3 speed had a 3.08 spicer rear. This rear will bolt right in to a chevy, but parts like brake drums, gears, and cables are hard to find for the spicer rear.

The od transmission swap is likely the cheapest and best swap. Using higher gears will affect the performance in every gear. With an od, you get to use your low gears for acceleration, and then have an extra gear that will shed at least 25% of the rpms at cruising speeds.

I vote for the od transmission. I have had a 59 gmc with 270 6 and 3.08 gears. I have had a 59 gmc with the 3.90 gears and changed them to the 3.38 gears. I now have a 1959 gmc with an od transmission and gears a little lower than stock for better acceleration. I have been there and done that... In my honest opinion, 3.90 gears with 28-30 inch tires and an OD transmission will give very rewarding results. Find an online calculator and run some numbers for yourself.

well I think putting a t-5 5spd tranny is the way to go. I was going to put a different ring gear from my 3:90.1 to the 3:38.1. but I was talked into the t-5. There is a lot of comments if you search t-5. I am sure the guys who went with the ring gear change is happy, but I wanted to do that as my last resort. I guess to each is their own. Its what you prefer.

Jaime, I would have recommended the T-5 also, as the necessary mods are simple and reversible. It also makes addition of power steering simpler. Except that Frnky4fngz said he requires the column shift.

Truckrolet, peace. I had no idea the R10 OD trannies were hard to find. I have 2, and about half the stovebolt trucks in the North Texas Inliners have them. I see them at swap meets all the time, but they must be the Ford ones (I don't actually look close).

I did a quick search online and was unable to turn up a single one. Hmph. I guess you learn something every day if you pay attention.

regards,
Leon

These trucks were not built for freeway speeds. There were very few freeways back then. They were built for hauling, farming, ranching, delivery, construction. Leaf springs all around, king pin axle, manual steering, drum brakes all around, high profile stance. If they were built for 70-80 why can't he go 70-80? This whole post is showing that the transmission and rear end ratios were not conducive to 70-80. To say they can go 80 all day long is a comment to make a point but rubbish. Not safe to drive over 65 in my book.... and I'm stretching my common sense at that. The point is not that you can't wind them up and eventually "get" them to 70-80 on a flat straight-away, it's that they are not built to swerve, curve, take a dip or stop at those speeds . The brakes and suspension are NOT up to that challenge. The ice cream will pop right out of the cone on the way home. BTW: He said he wants his 3 on the tree, not a T5 or other non stock mods.

I tend to agree with bartamos.
He makes some very valid points.

The SM319 transmission would be the easiest bolt in swap. The main case is the same as the SM318 trans that originally comes in these trucks. Plus, they are very common. The trick is not to limit yourself to just looking for a truck variant of this trans, the passenger car trans is the same, and will directly swap.
While it is true that the function of the overdrive is to lower engine rpm at a given speed, it does have the secondary function of allowing higher speeds while keeping the rpm down. I have no problems running one at highway speeds (70+) with stock suspension, steering, and brakes.

LgBOX55, Good points/info. I do expect to hear many responses from truckers who have had no problems. Those who have had a problem can not respond. BTW: The overdrives usually came with 4.11, that seems like a great combo. As I believe has been said, the OD gives about .70:1.

If you have every single steering and suspension component in brand new condition and adjusted correctly and your brakes are functioning properly, 70-80 mph is not a problem. That is, unless there is anyone else on the road that you kill because you lost control for what seems, at the time as a minor bump or slick spot that causes you to lose control. These trucks ain't exactly agile.

"Very first post asks about an OD transmission or a gear change to get the truck up to speed. Either of these options would make the truck "NON-STOCK"."

the very first post concerns a TF truck, a series where both the 3.38 rear gears and the OD 3 speed were factory options, it's disc brakes that'd make the truck "non-stock"

Bill

Back in the day, 1970 ish, I drove a 57 3100 with 3.9, had a 327 and sm420 all stock drum brakes, gas tank behind the seat etc. It had no problems cruising at 70 on a trip, and real good mileage too. And still here 40 years later to talk about it.

If you people would quit responding to him maybe he'd go away.

Cletis: Not sure who you mean? Regardless, coming from you, a Master Gabster, is rude and uncalled for here. Do you want everyone who does not agree with you to go away? That's ignorant. As the attitude cop on here, you sure give a great example.

"If you people would quit responding to him maybe he'd go away."
cletis,
What, and miss all of the fun? I get a kick out of how worked up some folks can get over trivial differences of opinion.

Another "trivial worked up" response. I got a kick out of this:

"70 MPH in a stock AD truck is pushing way past the safety sensibility limit. I recommend that you drive somewhere that you can't harm anyone including yourself and accelerate to 45-50 mph and slam on the brakes and see how long it takes to stop and how it handles during an emergency stop. Then think about what would happen with the addition of some loose gravel or slick road conditions. I understand what you are trying to do in terms of being able to go more than 45 mph without redlining the engine. I put a late 60s/early 70s six lug 12 bolt rear end with 3.73 gears out of a 1/2 ton truck in my 50 1/2 ton and it is much easier on the engine and I can keep from being blown off the interstate."... 52Carl awhile back.

Hi,
I replaced the original 3.9 diff in my 56 with a 3.38 a couple of years back. Pickup has the original 4 speed and 235. The gearing change helped a lot for freeway driving, but it doesn't climb hills nearly as well. 65 on the freeway is comfortable. I wouldn't go much faster than that. I still stay in the right lane and keep plenty of distance from the guy in front.

Other changes I considered mandatory were 3pt shoulder belts, tapered roller wheel bearings, new kingpins and tie rod ends, all new brakes with dual master cylinder.

I added sound deadening and insulation too, which obviously doesnt do anything for the engine but helps from the driver's perspective. Another simple tip that someone else mentioned is to make sure your valve clearances are set correctly - makes a heck of a clatter at freeway speeds otherwise.

Finally, make absolutely sure your brakes are adjusted evenly so you stop straight in a panic situation.

Hope this helps answer the OP's question.

Can you explain what you perceive as "worked up" in my post above? And what exactly is trivial about being concerned about someone possibly going overboard in modifications to a vehicle that was not designed for it?
Carl

That's exactly what I wanted to know about your comment. I didn't feel mine was worked up trivia and you don't either. I don't let bashing me stand unanswered. I don't react to anyone unless they are rude to me first. That's how I roll. Your comment to Cletis was off topic but not censored for some reason. Cletis was off topic and sort of rude, no censorship. Just me when I defend my opinion. SWEET is being as fair as he can without stifling good info. I don't really like this nonsense back and forth, but bullying is not tolerated by me. None of my opinions or suggestions are trivial or off topic, and "worked up" is not a way to comment on someone's thoughts they put in here, someone will find value it them. That's what a forum is for. So look at what you said and see if you still stand by it before you continue to act like you don't understand that your post, I found, is not as "passionate" as any I have posted.

"70 MPH in a stock AD truck is pushing way past the safety sensibility limit. I recommend that you drive somewhere that you can't harm anyone including yourself and accelerate to 45-50 mph and slam on the brakes and see how long it takes to stop and how it handles during an emergency stop. Then think about what would happen with the addition of some loose gravel or slick road conditions"

BTW, I totally agree with you on this and my comments are the same as yours about speed. But it is totally weird that you say some are "worked up about trivia" and you gave a comment about "losing control and killing someone..." in this very post.

Everybody take a break.