45mph w/ 5.13 rear ratio how can I go faster

[Geoff Weeks]

I come up with 4.05:1 @2100 would be 60 MPH with 9.00x 20  4.19:1 with 10.00x 20.

[steve s.]

If you added a transmission  with a .75 overdrive, and changed nothing else, you could run 60mph at just under 2100 RPM. Simple.

[JoeH]

Simple til you have to change driveshaft length etc.

[Geoff Weeks]

I took a look though my old (er) truck manuals to see if I could find something where the trans ratios were the same.  I was unsuccessful, I did notice that your trans ratios are fairly close together.  Raising the rear ratio may make it hard to start on a hill unless a different trans with a lower starting gear is used. Most 4 and 5 speeds have from the mid 5's to the low 6's for the bottom gear.  Granted a gasoline engine in the 700 CID range has a lot of bottom end torque, the clutch could take a beating if the overall reduction in bottom gear is raised significantly, as would be required to gain 15 mph of road speed. The "massive" torque available from a 700 cid gasser may be why a trans with deeper reduction was not used, too easy to blow it apart with deep reduction gear sets.  If you did find a trans with deep reduction, you would have to be careful in lower gears not to rawhide it.

 For the above reason, I would look long and hard at finding a different trans to use and not try and do all the change with the rear ratio alone. Keep in mind changes to the trans will effect the pump drive as well.

One problem is my manual collection is more recent, from the times of diesels and road tractors primarily. I do have a set for my forties K IHC's and nothing matched up there for a 4 speed.

Edited September 29, 2023 by Geoff Weeks

[67RModel]

On 9/28/2023 at 8:13 AM, mack31 said:

Thank you for the replies. We have a 5 speed trans.

But your literature shows its a 4 speed. Which is it? Also what is the tachometer say when you are maxed out at 45mph? Is the tach / speedometer accurate?

Don't know how big of a pain it would be but you could just go the two speed rear axle route. There has to be a pile of hydraulic brake two speed rear ends laying around from Loadstar and S series Internationals with 20" dayton hubs already installed. A low 5, high 3 ratio split was very common, say like 5.32/3.90. Probably wouldn't be that bad of a job. Would probably have to get a new driveshaft made or yours modified. They yokes probably wouldn't be the same between your shaft and the "new" axle. Keep it in low range and drive it like you normally do and then once in top gear switch the rear end to high range. Pretty simple....

[Geoff Weeks]

Actually no most of the hyd braked 2 spds are in the 6.14 high to may be mid 5's 17K (or there abouts).  Once you jump up into the 20K axles most are air braked. If you could find a hyd braked axle in that range, than changing the gearing would be easy. The 20 K axles use 16 and 16.5 inch ring gears and are also in common with the 38-40K tandems, The lighter axles often found in Loadstars and the like are 15" ring gear. There are much more limited range of ratio's in the smaller size. The carriers do not have the same bolt pattern and you can not substitute one for the other in the axle housing.

 The reason is most gassers (which would use hyd brakes) have a gov speed in the 2600 to 3000 range.

 I had an 2 spd out of a Loadstar and I know.  The heavyer  axles, like the 20K are the same center drop-out as the Eaton/Dana tandems in the 34-40K range. Far more ratio's were made for those axles than for the lighter one. That said even in the heavier axles very few  were made with the high range in the 3's, they are out there but not common. th

 When I put 2 spds in my Marmon I had to re ratio to get what I wanted. None could be found already with the correct ratio. I agree a two speed would be the ideal way to go, and a photo of the drop-out center section (and any casting numbers on it) may show if that is an option.

 A five speed with O/D in top gear of around .73 would also do, as long as its lowest starting ratio keeps the overall reduction about where it is now.

 Both options may require new driveshafts, which can get expensive. Mine for my K just set me back over $800.

[High Binder]

Not being negative, sarcastic, or bashing, but this thread reminds me of the situations I've faced numerous times. Do I keep it original or modernize? Just remember the old cliche, "Speed cost, how fast do you want to go?". I just run the backroads and don't worry about it. 

[67RModel]

Yea I thought about this too. I really hate to cut an antique truck up like this that is all original and "modernize" it but I get it. Personally I like to keep things original as possible. I think the slower speeds and lack of creature comforts are part of the nostalgia. For me if I had to get something this nice and original to highway speeds I would just rather trailer it to the location, but I realize that is not possible for everyone.

[doubleclutchinweasel]

The girl is pretty, but she can't cook.

Or, is it she can cook, but ain't pretty.

One way or the other...

[tjc transport]

4 minutes ago, doubleclutchinweasel said:

The girl is pretty, but she can't cook.

Or, is it she can cook, but ain't pretty.

One way or the other...

no biggie.

i will take the looker that cant cook. i am a good cook. 😁

 

[Geoff Weeks]

Trailering might be the cheapest way to go.  If distances are long the fuel bill is going to be big even if you could drive it.

 I spent some time looking through a diff catalog. There are less that 1/2 dozen front loading diffs with a 5.13 ratio. SO if it is front loading AND we get some pictures, we MIGHT be able to find out if there are other options.

Trans change is likely going to be part of the equation also, with that come possible bell housing and most likely driveshaft changes.  All would be hidden underneath and would look stock from the outside. 

 I agree I wouldn't want to cut up something like that, and things like tread width can vary leaving you with an axle that sticks out too far if the whole rear is changed.

 Any change is going to a an expensive undertaking, but knowing what might be possible will help make the choice of what to do easier.

[mack31]

Thank you guys for all of the input. My head is spinning but I will have to figure what the best route is and is it worth it. 
 

I can fix and run the pumps no problem but when it comes to the drive train I am looking for help. 

[Geoff Weeks]

Best thing that can help is a picture of the rear end from the front, any casting numbers you find on the drop-out (center section, hogs head, pig or what ever slang is in use in your area) and same for the transmission.

We need to ID these two items in order to see what can replace the current gear sets with the least amount of changes.

 A check on line of the Mack model numbers leads nowhere for either the trans or the rear. If you are lucky, Mack didn't make them, but bought a vendor supplied unit, and we have to figure out who that was and what they call that model.

[mack31]

Here is my carb. Does the rectangle next to the carb have anything to do with it. I’ve was wondering if this truck has a Governor on it. 

[Geoff Weeks]

10 minutes ago, mack31 said:

Here is my carb. Does the rectangle next to the carb have anything to do with it. I’ve was wondering if this truck has a Governor on it. 

Bet on it. 700 cid would be a whole lot of hurt if it came apart.

[mack31]

On 9/29/2023 at 9:29 PM, Geoff Weeks said:

Best thing that can help is a picture of the rear end from the front, any casting numbers you find on the drop-out (center section, hogs head, pig or what ever slang is in use in your area) and same for the transmission.

We need to ID these two items in order to see what can replace the current gear sets with the least amount of changes.

 A check on line of the Mack model numbers leads nowhere for either the trans or the rear. If you are lucky, Mack didn't make them, but bought a vendor supplied unit, and we have to figure out who that was and what they call that model.

Geoff you have been great help. I need more help with my 1930 trying to get it running. Had an old battery that couldn’t keep a charge but the engine would turn over. Replaced it today with a new battery it cranked over twice. Now we have nothing. It won’t do anything not even a click. Please help 

12v system. 

[Geoff Weeks]

1st an most likely is a bad connection.  If the ground side goes to the frame, and the the engine is connected to the frame with a braided strap, it adds connections and likely fail points,  The starter is the highest amp draw on the battery, so run is few connections between it and the battery as possible. Make sure all connections are clean and tight. On my old six volt stuff I run the ground right to the starter mounting bolt, or a bolt on the engine or transmission that is at least 3/8" and make sure the metal around the bolt is clean.  I then replace any braided straps between the engine and frame to make sure the engine is bonded to the frame and the same with the cab/chassie.

 I don't know your engine, so am going to give general advice which may or may not apply:

if the starter has a remote solenoid switch make sure it is conducting when activated. A bad ground to the cab thought the mounting bolts, or a bad ground of the cab to the engine both can cause failure.

If the starter is operated by a mechanical link and "button" on the floor, the contacts in the mechanical switch on the starter could be at fault.

 The starter itself could need some attention, Starters of this vintage often had "oil cups" at the rear and sometimes front end. Many times the starter motor shaft ride directly in the cast iron cover and the oil wick is all the keeps it from galling on the shaft. My manual calls for them to be lubed every 500- 1000 miles! Most never see any attention.

 The starter could have internal problems, like a open segment on the commutator or one bad winding on the armature.

If you suspect the starter, pull it out and connect up to a battery with jumper cables, it should kick and spin (just do a quick test, don't run for a long time with no load).

Because the truck cranked over on a new battery but then doesn't, could also be something like a stuck generator cut-out drawing the new battery down when the engine isn't running. Check for sparks when you connect the battery leads, there shouldn't be any, with everything turned off (headlights etc).

 A test light, or volt meter can be of help to check for voltage drop across connections. A quick way to find poor connections on the starter (if it will crank at all) is heat, feel the connections after the starter has cranked (you did say it would crank with a fresh battery) and any warm or hot connection is a bad one.

 

[mack31]

On 10/16/2023 at 8:20 AM, Geoff Weeks said:

1st an most likely is a bad connection.  If the ground side goes to the frame, and the the engine is connected to the frame with a braided strap, it adds connections and likely fail points,  The starter is the highest amp draw on the battery, so run is few connections between it and the battery as possible. Make sure all connections are clean and tight. On my old six volt stuff I run the ground right to the starter mounting bolt, or a bolt on the engine or transmission that is at least 3/8" and make sure the metal around the bolt is clean.  I then replace any braided straps between the engine and frame to make sure the engine is bonded to the frame and the same with the cab/chassie.

 I don't know your engine, so am going to give general advice which may or may not apply:

if the starter has a remote solenoid switch make sure it is conducting when activated. A bad ground to the cab thought the mounting bolts, or a bad ground of the cab to the engine both can cause failure.

If the starter is operated by a mechanical link and "button" on the floor, the contacts in the mechanical switch on the starter could be at fault.

 The starter itself could need some attention, Starters of this vintage often had "oil cups" at the rear and sometimes front end. Many times the starter motor shaft ride directly in the cast iron cover and the oil wick is all the keeps it from galling on the shaft. My manual calls for them to be lubed every 500- 1000 miles! Most never see any attention.

 The starter could have internal problems, like a open segment on the commutator or one bad winding on the armature.

If you suspect the starter, pull it out and connect up to a battery with jumper cables, it should kick and spin (just do a quick test, don't run for a long time with no load).

Because the truck cranked over on a new battery but then doesn't, could also be something like a stuck generator cut-out drawing the new battery down when the engine isn't running. Check for sparks when you connect the battery leads, there shouldn't be any, with everything turned off (headlights etc).

 A test light, or volt meter can be of help to check for voltage drop across connections. A quick way to find poor connections on the starter (if it will crank at all) is heat, feel the connections after the starter has cranked (you did say it would crank with a fresh battery) and any warm or hot connection is a bad one.

 

Ok so we have power. Which is good. 
 

When attempting to start there is a grinding sound and then no movement. I did spin the fan and attempted a start again but it sounds like the starter tries to spin but then nothing. 
Should I pull the starter ?

[Geoff Weeks]

Yes, many starters of this era used inertia drives. they get "thrown" out into the ring gear by the starter starting to spin. They have a large spring that can break, esp if the truck was 6 volt and now is using 12 volt through the same 6 volt starter.

 Pull the starter and look at the starter and ring gear for damage.