Dodge L600

[Aaronw]

I've got a number of these L700 kits due to them being packaged with the trailers. I was thinking of doing one base model L600 with a slant 6 or 318 and hydraulic brakes.

It is easy enough to remove the air brake equipment, and perhaps add some wheel cylinders, but I'm not sure where I should mount the master cylinder since it is a tilt cab. Would it be mounted near the motor with some kind of linkage to the pedal, or mounted to the cab with a hydraulic line running down to the frame?

I haven't had much luck searching for photos of the engine compartment, and those I have found tend to be air brake equipped L700s.

[mistermodel]

Aaron,this kit has some shortcomings with brake detail.It's a weird one because it has the master cylinder that you need,and air hoses for the trailer,but no air compressor.I'm not knowing if it was correct to have a trailer only air system ,with hydraulic truck system.

In this link you will see the master,it's not a L700 but it's the same location as the kit part.I'm sure the other pages here will help also.

http://dodge-semis.com/Brochures/1973MD/pg08and09.html

Edited November 9, 2010 by mistermodel

[mistermodel]

Found this pic,notice lower right.

http://s870.photobucket.com/albums/ab267/AngryDawg/Dodge%20L700%20medium%20duty/?action=view&current=100_1399.jpg&newest=1#!oZZ36QQcurrentZZhttp%3A%2F%2Fs870.photobucket.com%2Falbums%2Fab267%2FAngryDawg%2FDodge%2520L700%2520medium%2520duty%2F%3Faction%3Dview%26current%3D100_1399.jpg%26newest%3D1

A few more detail pics here also.I'm glad I found this ,I had the tracked one saved on my old computer,but lost it when it crashed and never found it again till now.I'm gonna build one,just got to figure out what to use for the tracks

[Aaronw]

Funny, I may be putting the cart before the horse. I haven't really looked the kit over that well, maybe I should be looking for air brake details, having just assumed the kit was set up with air brakes. Oh, well that is why I'm starting one, so I have a better idea of what is needed before doing anything fancy with it.

If you are talking about building a tracked L700, you might try looking at the Lost in Space chariot. There was one posted recently and it has a good set of what look like a snow cat suspension and tracks. I ran across that photo of a tracked flatbed L700 too, assuming that is what you meant.

[Aaronw]

Here is the post with the tracked truck.

http://www.modelcarsmag.com/forums/index.php?showtopic=36952

[mistermodel]

Aaron,never thought about that kit,I was thinking a military kit for those parts.

I also saw one of those tracked dodge's using a pick-up cab of the same vintage,wish I new who made them so I could do a google search.

Back to the L series kit,these are fiddly kits,but build up into a nice model.I need a couple more,cheap,all but the flat bed trailers look good.Just too many things to build for a decent flat bed,mainly a proper frame,I'm turning 2 into a A train set up.No frame is fine for the box trailer ,but a flat would fold up without a frame.Plus the 40 fords have great tear drop lights that are good for custom petes and such,and good vintage police/fire goodies

[Aaronw]

Aaron,this kit has some shortcomings with brake detail.It's a weird one because it has the master cylinder that you need,and air hoses for the trailer,but no air compressor.I'm not knowing if it was correct to have a trailer only air system ,with hydraulic truck system.

In this link you will see the master,it's not a L700 but it's the same location as the kit part.I'm sure the other pages here will help also.

http://dodge-semis.com/Brochures/1973MD/pg08and09.html

Now that you pointed this out, I've done a bit of research, and it appears the kit has a vacuum over hydraulic brake system. Hydraulic brakes for the tractor and vacuum brakes for the trailer. This type of brake system seems to have fallen out of use for commercial vehicles in the 70s because the vacuum brakes did not work all that well compared to air. The vacuum was supplied by the engine, and a tank was used to store vacuum. Air over hydraulic brakes also exist, but these require an air compressor so a bit more complicated.

This type of braking system is still available for smaller trailers like campers or boats. It looks like diesels don't create enough vacuum so require an electric vacuum pump which might be another reason they fell out of use, diesels were getting popular in the 70s.

http://www.lowcosttrailersupplies.com/Merchant3/merchant.mvc?page=LCTS/CTGY/Vac-Hyd

I had never heard of this type of brake system before.

Now I guess I'll have to swap parts with a Ford C cab, to do an air brake equipped L700 and hydraulic equipped C600.

Edited November 11, 2010 by Aaronw

[mistermodel]

I wouldn't of figured that system was used on a semi unit,I know that dodge would of been a city truck with smaller payloads ,but still bigger than a camper or boat.

[highway]

It looks like diesels don't create enough vacuum so require an electric vacuum pump which might be another reason they fell out of use, diesels were getting popular in the 70s.

Even though this is sorta on topic and sorta not, you are right that diesels do not create enough vacuum on their own, not even to operate the power assist booster on diesel pickups. I have a 1:1 Ford F350 diesel, and it has a belt driven vacuum pump. It's sole purpose in life is to supply vaccum to the power brake booster. Ford also, at least in the early 90s trucks like mine, a 90, also used a HydroBoost brake system on the heavier duty Super Duty, which equals an F450 or F550 today. These drew the power brake boost from the power steering hydraulics.

[Aaronw]

I wouldn't have either, but I found quite a few posts on various old truck forums from people who are restoring old trucks that have this type of system. Under current laws I don't really see the point, the driver would need a class A licence so why not just provide air brakes. It looks like in many states there were no commercial licensing requirements until the 1980s. I guess these hydraulic / vacuum brakes were either cheaper or considered easier for drivers to learn to operate.

[Aaronw]

Even though this is sorta on topic and sorta not, you are right that diesels do not create enough vacuum on their own, not even to operate the power assist booster on diesel pickups. I have a 1:1 Ford F350 diesel, and it has a belt driven vacuum pump. It's sole purpose in life is to supply vaccum to the power brake booster. Ford also, at least in the early 90s trucks like mine, a 90, also used a HydroBoost brake system on the heavier duty Super Duty, which equals an F450 or F550 today. These drew the power brake boost from the power steering hydraulics.

I never really thought about that but it does explain the somewhat odd brakes on some under 26,000lb medium duty trucks I've driven.

[highway]

I never really thought about that but it does explain the somewhat odd brakes on some under 26,000lb medium duty trucks I've driven.

And some of the odd parking brake systems, too! Trucks like Ryder and Budget 24 foot vans in the non CDL weights use a drum mounted to the driveline of the truck for a parking brake. I used to drive heavy duty wrecker, and it was more or less on the job training when I started, and I found out about driveline parking brakes the hard way!

I was dropping a 24 foot van off at the local International dealer, and it was company policy to drop the driveshaft so it would not destroy the transmission during the tow, so the rear portion of the shaft was in one of the wrecker's toolboxes. I had to sit the front tires on blocks of wood to get the tow bar out from under the front axle, and I did that and was putting the axle attachments back in the toolbox and to grab the driveshaft piece to reinstall. I heard a small thud and looked back at the truck and seen it rolling away from the blocks and straight towards the street! I ran after it and grabbed the front bumper and somehow held the truck back from rolling to the street. I still do not know to this day how I was able to hold it, but I held that truck until one of the guys from the dealership brought me some wheel chocks. After he chocked the wheels, I said I don't know why the truck did that, the brake was set, and then the mechanic told me to look at something under the truck. He pointed to the small drum right behind the transmission and told me that was why the brake didn't hold, because that was the parking brake!

[Aaronw]

My Landcruiser has a driveline mounted parking brake, it does present some positive and negative features.

One of the odd trucks I'm thinking of was an IH S1600 that had some kind of an electrical booster. It had a spring brake with a button like air brakes, a handle for what was probably a driveline brake, and if you had your foot on the brake when the engine was off you could hear an electric motor running, until you relaesed the brake pedal.

I also drove a 1999 Ford F-450 diesel that had the hydraulic power steering / brakes you mentioned. I didn't think about it at the time but it was kind of strange.

[Jim B]

Have you check out Old Dodges? They might have some good photos.