The Stovebolt Site Forums The Shop Area Engine Shop 3 in a tree v 4 on the floor

Hi all, I have a 54 ad 1/2ton pick up, it has a 3speed column change and a 235 motor, would there be a benefit to swap to a, 4 on the floor from a 55 2nd series be any benefit to me.is the gearing any different ? thanks.

only that you will have a deep 1st gear which you wouldn't use under normal daily driving. if you are going to be pulling or towng it may be benificial for staring sometimes if needed
ron

3rd gear on the 3 speed and 4th gear on the 4 speed are the same,I just got a 53 GMC with a 4 speed,My 52 has a 3 speed,and I can't get to the brake peddle when it's in 2nd gear so I have to shift out of gear to stop I would quess I'd get used to it after driving it so I'll see.But I see no advantage to installing a 4 speed box.

Pete

A 4 speed is ok if you're going to work with it. 50 to 60 years we wouldn't have considered a 3 speed. Today, I don't work with them any more and I don't have the patience to put up with the slow reverse gear. We have 45 degree parking on our Main Street and I have to wait until there are no cars in sight for 100 yards to back out with a 4 speed.

The 4 speed from a '55 2nd would not work in a '54 without changing the rearend to open driveline.

I have the 4-speed behind my 235. 1st gear is very low. Top speed in 1st is around 6 or 8 mph. Way too slow for normal traffic. Good for pulling a float in a parade, but that's about it.

The 4 speed is used for daily driving in 2nd-4th gears. There are syncros in all these gears, so the advantage is of being able to downshift to 2nd gear. 1st or granny gear is generally not used. So basically you would have a fully sycroed 3 speed and a granny low. I still believe you might have driveline issues with this particular swap. The 4 speed also adds about 75 lbs to the vehicle.

Hay, thanks for that guys, I will leave it be, as it is, I didnt realise how people could get SOOO attached to a vehicle .... Till I got one !! thanks again all

My trick came originally with a four in the floor, but I have a friend who has a three on the tree with overdrive that he would sell me for a hundred bucks. I don't plan on pulling large things but I do plan on traveling in the truck good distances. Would the 3 speed be better? How much pulling power would I actually lose?

If the overdrive transmission is in good shape, its well worth the money. It will cut your rpm's by 30 % in high gear when its in overdrive. With overdrive locked out, you will have a 3 speed like what you have now. If you are still running 6 volt, I don't think Chev ever offered a 6 volt overdrive, but you can use a relay and solenoid from a 55 or older Ford. Overdrive was a popular option with Ford, and the Warner tail section is the same Borg Warner as what GM used. Most of the parts of the 3 speed you have now will interchange with the front section overdrive transmission. I have been running Ford overdrives for over 45 years and am in the process of putting one in a 1950 GMC. I like an overdrive much better than re ratioing the rear to 3.55.

Now this is a three on the tree with overdrive that came out of a car my friend told me. He doesn't know how it was set up or anything and he doesn't have any of the linkages or know how on setting it back up. My truck will be a 12 volt when I finish and if I changed from a four in the floor to the other will it be that much in modifications to the vehicle? Since it was an option to have a column shift I would think that it wouldn't be too much. How does the overdrive kick in on most of the transmissions like this?

First in order to either lock the OD in direct or allow it to shift into overdrive, you need a cable. Old vehicles had a handle marked overdrive, but anything from a PTO cable to a hood release cable will work. With the cable pushed in, a governor in the very back of the transmission would signal the relay when 28 mph had been reached. At any speed above 28 mph, you could let off the gas and it would shift into od. When you feel the shift, you step on the gas and its in od. The relay is a 2 part relay. A heavy winding causes the solenoid to shift the od unit and the light winding holds it in. If you want to want to shift back into direct, you step down on the gas and a kickdown switch interrupts the ignition momentarily and allows the unit to shift back to direct. On Chev, the kickdown switch was at the carb. On ford it was under the gas pedal. If you are driving around town and don't want to use the od, you pull the cable out, and the transmission will function exactly like what you have now. I usually leave my overdrives in the locked out position at speeds below 40 mph because they are free wheeling at speeds below 28 and at speeds below 40, the engine just doesn't turn fast enough in od. Here is a wiring diagram for an od http://www.classictruckshop.com/clubs/earlyburbs/projects/over/od-diagrm.jpg

I'm pretty new to all this and was planning on keeping my 3 on the tree and re-doing the rear end to go a little faster. My understanding was that the rear end was keeping the truck from going over 55/60 mph. Can overdrive give the same results?

Basically yes.

An overdrive usually gives a 30% reduction in engine speed at a given road speed. Or if you have the horsepower to do it, a 30% increase in speed.

The exact numbers depend on the gears in the OD so I'm just using 30% to illustrate.

The advantage as I see it of using an overdrive over changing the rear gears is that you then have the best of both. You have the lower gears that allow hauling a heavier load and the ability to run at lower RPM at speed.

If you change the rear gears you loose the leverage those lower gears represent.

I don't know why Crenweldge prefers an overdrive to changing gears, but I'm sure he has a reason and will come back and share.

I prefer a transmission that has an overdriven top gear. A 3-speed with an overdrive means you are shifting the 3-speed and managing the overdrive for best performance.

I have a 4-speed with an overdrive and find it annoys me to manage that overdrive. If I ever replace that trans a 5-speed or maybe a 6-speed will go in.

This same logic is why given the choice I'd choose a 4L80e over adding a Gear Vendors overdrive to a TH400. With the 4L80e you are not managing that overdrive the transmission and its control box are doing it for me.

Steve, maybe I'm confused again. You know I get that way at times. I think neilnip wants to go faster and wonders if putting a SM420 from a 55.2 would make him go faster. High gear would be the same. He would have a first gear he would never use and a reverse that would terribly slow. Any of the later 4 speed overdrive transmissions would make him go faster, but they are usually only .80 overdrive. However, they came out of passenger cars, not 55 model trucks.

I also think that morethanaframe has a SM420 now and has a chance to buy what I would assume to be a SM318 with a Warner OD unit for $100 which is a bargain. I have seen them fetch $400 on eBay. Maybe I'm making too many assumptions. But the 3 on the tree linkage will probably work on the front section of the overdrive transmission. The only difference in a regular SM 318 and an overdrive is the mainshaft. The housing is the same. Even if he has to spend a couple of hundred on a relay, etc., it would be a cheaper way to go faster.

The main reason I like overdrives is because I have been fooling with them for almost 50 years and I used to show tail lights in an unmentionable make of car on this forum with an overdrive to lots of 283 and 327.

My reason for preferring OD because I like a 3.90 or 4.11 around town. And of course out on the highway, I can drop the rpm by 30% I have driven some 3.55 rears and they lacked the snap away from a red light that I like. I think a 270 or 302 in front of 3.55 is just fine. If I ever win the lottery, I'm gonna buy a bunch of Tremec boxes.

If' Ive gotten way off track, I'll go drink a beer and maybe think straighter.

Kenneth its too late for me to judge... I've already had one beer tonight and its past my bedtime.

I was trying to explain why I prefer a transmission like the T-5 or the Tremecs to something like the old 3-speed with OD or any other add-on overdrive.

I may not have been answering or responding anyone's question except the ones the thread inspired in my own head.

I once owned a Saginaw 4-speed that had the OD from a 3-speed adapted to it. I loved the idea when I had it built. I hated it in daily use. I had it built in the gas crisis days of the 70's and sold it six or seven years ago for far more than I ever thought it could be worth.

Today I have a Corvette with the DNE 4+3 which is basically a Super T-10 4-speed with an automatic overdrive for a tailshaft. That automatic overdrive is the feature I like least about the car, though it is why I can get 26 mpg on the highway in a car that can most likely out run your old 292 or 351 along with those 283 and 327 powered competitors.

I understand your reason for liking overdrive and agree it makes sense. I prefer my overdrive as an integral part of the transmission instead of as an add-on that is managed separately. I find it more pleasant to drive that way.

I went and took pictures of my friends three speed while it was on the floor. I am unsure if it is a SM318. The numbers are like this on the side. I have several other pictures for different views. This is all he has to sell for it. Will it cost me a lot for linkages for this style? What do I check to know of the condition?

That is a Borg Warner overdrive. All you need is a cable to operate the lever. When you pull the cable, it will lock the overdrive into direct and it will perform like a normal 3 speed. When the cable is pushed in, it will allow it to shift into overdrive. The part in front of the overdrive should be the same as what you have now except it has a mainstaft to mate it with the overdrive. If you take the shifter cover off the transmission, you can see the general condition of the gears. However, the wear parts will interchange with what you have now. As for the overdrive unit itself, the main thing is that it didn't run out of oil. Parts will interchange with any vehicle of the period that used overdrive. The only thing you would probably need for sure is the relay. They are on eBay for about $100 all the time. They don't have to be from a Chev. The kickdown switch can easily be substituted with a toggle switch.

What is special about that relay?

The popular and common Bosch relays are less than $5 each. Even if it took three of them to replace that original type you'd be money ahead.

Back in the day of the overdrives, continuous on relays were not commonly available. I tried a headlight relays back in the 60's and and they only lasted about a week. The Bosch or Hella relays have only been available here the last 20 years or so. I have never tried one, but our trucks now have a bank of 20 or so relays and they almost never fail. They even power electric wipers. Here is a schematic of how the overdrives were wired. http://picasaweb.google.com/crenwel...N9tJKHsYFELgbeyFTDgw#5431562618455431554 I would think that a Bosch type would work. However, I remember from taking an OD relay apart, they had a light and a heavy winding. It seems like the heavy winding was to energize the solenoid and the light winding was to keep it engaged, but I'm not sure.

Based on the diagram I see no reason a cheap modern relay could not be used. The wire sizes marked on the diagram are 14 and 18 gauge wire, so they aren't carrying a lot of current.

My quick google search for 'Bosch rely' turned up a 30 amp for three bucks. I didn't think of Hela, but clearly something designed for continuous duty would be the ideal.

I'd sure try that before spending $100 on a used relay.

I have 4 OD installs belonging to customers running around the freeways of So Cal using the Bosch type relays. Some have been in service for several years and no problems. I have the original GM unit on my truck and find virtually no difference in the performance. As mentioned the originals are in excess of $100, the Bosch type are cheap and/or free at pick your part. Something that hasn't been mentioned in the quest to "go faster" is that the brakes and steering were about as good as the original 50 mph top speed allowed. Something to think about.
Fred

I agree with Fred on this.

If driving from Fort Worth to God awfull west texas there is not a lot of traffic. But buzzing around the inner states of Dallas I keep in mind that my truck is of 50s vintage. This was the time when roads were crappy and people were in the same predicament in terms of speed and stopping distances. 2010 brings snappy little cars that are light, zip in and out of traffic for no reason, and stop quickly with modern disc brakes.

When I leave the "safe distance" for safety people honk horns, give me the finger, and yell. They're not from around here. I smile because I like my old original truck.

Good luck