1st series hydrovac rebuild kit

[peter de vries]

Hello, Well i have finally found the time to pull apart my series1 hydrovac, and have found that apart from needing a seal kit all looks reasonable inside and should be fit for re-building. I went to my local Autobrake dealer but they had trouble finding appropriate part numbers for a replacemant seal kit for the unit. Would anybody be able to point me in the right direction for either part numbers for a replacement seal kit or suppliers for one. I am in Australia but am happy to source from the USA for parts. Thanks for your help. Regards, Pete.

[Fernando Mendes]

Peter,did you see this video about principles of operation of your hydrovac 1st serie?

[Fernando Mendes]

http://www.youtube.com/watch?gl=DE&hl=de&v=keChCevuKk8

[peter de vries]

WOW Thanks for that, what an awesome video! That is the exact model hydrovac in my truck. Have pulled it mostly apart now, just have to do the air metering valve assembly ( the fiddly bit) and see what that looks like inside...

[Fernando Mendes]

The principle troubles of hydrovac is cylinder corrosion(rusted),worn valve spring,gasket,

[Fernando Mendes]

Hi Peter.What did you find of wrong in your hydrovac?

[peter de vries]

I have made a start to pulling apart the valve assembly. The diaphragm looks ok so far and the piston is not seized which is a good start. I need to remove the assembly from the end of the hydrovac cylinder now to complete the dis-assembly as you cannot easily remove the last 3 screws with the valve mechanism still attached. Will have a look over the weekend hopefully! I reckon it will take quite a few hours of cleaning/ bead blasting components before things will be going back together again.....

[Fernando Mendes]

Do you have a manual figure to dissassemble it? I have and can send to you.If you need tell me still today because I will travelling this weekend.

[peter de vries]

Thanks for the kind offer. I actually have got myself 2 manuals now. Both the specific Hydrovac repair manual and the TM-10-1563 maintenance manual. All i need now is some spare time and a collection of seals/ gaskets etc and all should be good!

[Fernando Mendes]

http://img638.imageshack.us/img638/7229/imagem296q.jpg
http://img843.imageshack.us/img843/7264/imagem076.jpg
http://img13.imageshack.us/img13/2360/imagem304.jpg
http://img51.imageshack.us/img51/2328/imagem241y.jpg
http://img813.imageshack.us/img813/7396/imagem317.jpg
http://img197.imageshack.us/img197/7349/imagem303.jpg

[Fernando Mendes]

Peter,I have the TM10-1563,TM9-801,ORD9 SNL G-508(first and second parts)that I could discovered the CONTROL LEVER STUD NUT that I missed in november'2005 and since this month I installed a different type of nut thread.Through ORD9 SNL G-508 I got the type of nut and bought one(diameter nut 5/16" and 24G=24 threads per inch).

[peter de vries]

We are so lucky that the US army was so thorough in preparing their workshop manuals! I have had a bit of a look through mine but still have quite a few hours of reading ahead of me yet!

[peter de vries]

I have been thinking of fitting a flexible brake line where the hydrovac was to join the brake lines so that i can still use the brakes minus hydrovac so i can move the truck around my yard while i rebuild the hydrovac. I realise the brake performance will be a lot worse without the hydrovac, but the truck is empty so i presume it should still stop? Does anybody have any experience in using the brakes without the hydrovac attached?

[Fernando Mendes]

http://www.youtube.com/watch?v=gu8OE_Gv ... elated:eek:
Peter,see this owner truck has experience in driving without tires and clutch.rsrsrs...

[peter de vries]

have been bleeding my brakes for hours, wondering why the pedal is hard but the front wheel bleed screws are out. So i blew compressed air through the bleeder holes to see what is going on, and the air happily blows out around the brake drums. seems the last owner has removed the front brakes when they wore out and has plugged the lines inside the wheel cylinders to stop the fluid leaking out so the back brakes will still work. seems they didn't know about the isolator valve inside the chassis rail. would have saved them a bit of work. looks like i will have some more parts to buy now! was wondering why there was a set of brake shoes in the tool box when i bought it...

[Fernando Mendes]

Why don't you put pictures to share us your work?

[Chris_M]

Using the rear brakes only is quite risky. Especially when the cargo bed is empty. The opposite would be better. The main braking power comes from the front wheel brakes.

Regards,

Chris

[peter de vries]

sorry for no replies for a while, have been out on a camping trip. Have taken my truck for a run around the paddock to try out the brakes, and have found out that i reckon the rear wheel cylinders must all be seized solid as there is not one ounce of braking effort no matter how hard i push the brake pedal! Just as well the handbrake still works quite well! Looks like i will have to take all of the brakes apart for some serious attention. I am starting to realise that the last owners had used this truck for many years on their farm using only the handbrake for stopping. Will post some pics soon after i work out how to host them on a site that i can access...

[Fernando Mendes]

Just as well the handbrake still works quite well!
MINE TOO.But I don't give up to always restoring my brakes.I already dismounted all hydrovac and ever continuing this maintenance.Want is can.
sorry for no replies for a while When you have a doubt write to me and I will reply to you.

[Chris_M]

Same with my truck when I bought her in 2007. It looked like the vehicle has not been moved the last 20 years. Everything was dried out and stuck. But replacing the master brake cylinder and cleaning all wheel cylinders as well as adjusting the brake shoes took them back in (almost) perfect condition. I only have the problem right now, that air slowly enters the brake lines from somewhere. I don't know where from yet. Brake hoses are in good condition. Maybe you guys have an idea?

Regards,

Chris