Chrysler Forward control amphibious

[Jack Innes]

Thank you David.

The cab was built post service. It looks like someone capable of aircraft work built it & it is very functional. The original trucks had either a fiberglass hard top as you described or a soft top. This truck has evidence of the soft top.

Jack

[rob love]

A cooling system for a differential sounds very much like a technical failure to me. While common on controlled differentials, I don't think I have ever seen it on a normal diff.

I wonder if today's synthetic oils might control the over heating.

[Jack Innes]

Rob,
There is a lot of discussion in the daily test results on the diff trouble & the efforts to overcome it. The end result seems to be the cooling system with the pump and the use of GM differential fluid available at that time. Both axles have limited slip devices. It is obvious that they went to great lengths to sort this out. One of the spare axle housings has 7 inspection openings machined into the casting & fitted with Plexiglas windows so they could observe what was going on inside in use.

I am sure you are correct on the advantages of modern oil meant for the job.

I also doubt that the vehicle will be expected to travel all day at 62 mph any time soon.

Jack

[rob love]

Also possible that the diff, with no airflow since it is located within a hull, would be subject to overheating no matter what oil was used. There would not be the dissipation that an external differential would have. A fault like this must have weighed very heavily against the vehicle. If the fault was consistant on all the vehicles, could you imagine a 600 mile roadmove? It would be almost as bad as the LSVWs, with them littering the sides of the highways.

Notable that on something like the LAVs, the diffs are outside the hulls.

[Jack Innes]

Rob,
I would agree that a long road move could tax the axles. Having the brakes directly coupled to the diff housing would transmit even more heat. Perhaps a full time bilge blower drawing from the rear diff area would serve two purposes.


I replaced the rear brake pads today ( had them on the shelf) & took the truck for its first drive. About a mile down the road & back through a very muddy field with deep ditches. I do not think much would stop the vehicle.
The steering ratio is about 24 to 1 so you can steer it with one hand but need to get used to a lot of turning.

Jack

[rob love]

Jack
I am envious. Congratulations...you have one neat truck.

[45jim]

Diff coolers are very common on race cars, you'll find plenty of sites where they warn of diff oil exceeding 280F during use. On diffs exposed to the airflow a finned aluminum cover is usually enough to deal with excess heat build up. With Independent rear ends where the diff is tucked up out of the airflow a small cooler with pump and fan are often placed in a remote location in the airflow for races. With this diff being all buttoned up and totally isolated from the airflow the addition of a cooler would be a common requirement. I am sure the diff with the windows was to determine where to locate the pickup tube. When you install one its important that the pump not suck air as that will aerate the fluid further degrading its lubricating qualities. The normal method is to use a plastic diff cover while the vehicle is run on a dynometer and see where the fluid is, and isn't.