miro

There is your problem, not knowing how much space from the back of the cab cross member to the trunnion, you should have one cross member right in front of the of the front drives, and have no more than two feet between cross members. Your frame is flexing in this area causing the wobble. Mack used to have a couple of different cross members that you can put in with out pulling the bogies. Maybe someone that works at a Mack dealer can help you source them. I remember that the were not expensive and not hard to put in. Mike

Also I don't see any cross members could you take a picture from the rear of the truck showing the cross members. Also are the bolts body bound bolts, this would help with strength? The old rivets worked quite well but it is hard to replace them in the field.

LMackattack, Those R700s, did they have pitting in the bearing shells? The 865 and 866 tolerated 0 antifreeze. If a liner, oil cooler or water pump leaked internally, In no time the bearings would flake and fail.

The original bolts were tamperproof slotted screws, to slow down theft.

If the frame has been shortened could you take some pictures of the frame from the back of cab to the fifth wheel and post them when you get back?

Like I asked before has this truck had frame work done to it?

He's already had them spun balance and the passes, I think you,re looking for something that is not there

I still think you're barking up the wrong tree. The front end is swaying in the sprung weight, the unsprung weight is reacting to it. I have seen this in brand new Superliners in the 70 and other trucks over the years. the only way to stop it on the Superliners was to put inside channel in the frame. The frame takes on harmonics at certain speeds and will not come out of it untill you get out of that speed. If the balance was that bad as in the Video the tire would actually lose contact with the road. I would like to see a happy outcome from all this.

I don't think that you have a Balance problem as the tire is not really bouncing the chassis is. Has the frame been stretched or modified in any way?How are the crossmembers and motor mounts?

With the side bolts on the main caps the only thing you can do is go oversize main shells. Also with 10 and 30 PSI oil oil pressure, is the crank undersized all ready, or the block been machined before?

It could be from Canada, built at the Oakville Ontario plant. The trucks built there had a maple leaf under the Bulldog on the door. The one above may have had body work done

Mack used to build the DMM complete as a 6 X 6 from the mid 70's. They were some of the first trucks to have early ABS (POS) Thay stayed the same untill I believe the 90's when the owners realised that that front axle and transfer case took a lot of load away from them, so Mack build the RD with a long wheel base and shipped them to Quebec to have a second steer axle put under them. They also had Meritor axles with PD lock amd axle locks and Chalmers suspensions for better traction.

I agree with Dragonwagon

You are right Rob, power steering is is just a closed hydraulic system, and the oil you put in really does not matter to much whether it is detergent or none detergent, I have never heard of power steering failing because you used atf or engine oil. The oils are more critical to engines transmissions and diffs.

The detergent in the oil does not foam up, what it does is hold the dirt in suspension, thats why you use none detergent in none filtered engines, to let the dirt fall out and not get circulated,in a normal engine with a filter the filter traps the dirt. ATF is a high detergent oil with a viscosity rating of about 10 but is not multi viscosity. The Ideal thing really is to put hydraulic oil in the system but you probably would not be able to turn the wheel in winter with summer grade and would burn out the pump with winter grade in the summer because it would be to thin once it got hot.

Mack recommended 15/40 oil when it came out. ATF before that. Found 15/40 worked better.

Have you tried a master oil guage to make sure its not a faulty guage or sending unit?

Has it had any work done to it recently?

Why not just clean them in mineral spirits, let the dry and reuse them!

If you're useing red antifreeze you replace the coolant fiter with an empty can or if it has taps to the filter turn them off. The red antifreeze has a different protection package in it. Depending on whose red antifreeze you are useing you don't have to check for many years and you need different test stips to check it. The regular DCA test stips always show red antifreeze being good.

If you have Mack rearends the bracket bolts to back the back of the pot housing and the housing has to be drilled and tapped for the bracket. Are your bogies walking? check the trunnion rubbers.

There is a guy here in Ontario that has 2 fully restored and uses them

Scotchlocks shouldbe banned

The twin stick is a Maxitorque trans main trans is 5 speed other stick is for low low gear, direct and reverse, Your right it looks like an F795T, Lot of power for a single axle.

Aw reminds of the days of the 866, low power complaint on an F model, they would put the cab down on me, the service manager would drive with a loaded set of trains and I would adjust the rack until it pulled good. A little warm but it got the job done when you don't have a dyno