Lmackattack

the air pressure needs to be above 60 psi to be pushed in without it trying to pop out. I think the actual pop out psi is closer to 40 psi but I always wait until 60psi to push them in

that aux valve needs to be traced to what its for. Like I said most R models had a blue vlave for tractor parking. If the yellow is pushed in first you had to make sure you pushed in the blue as well.

In this photo the 3 valves from left to right..... trailer supply......truck trailer parking........tractor only park

I was one to always say keep it original and such but now im 20 years older and I feel that is not always the best advice anymore.

These days I would recommend a air ride that is tried and proven.  If a hobby truck Airliner is one of those options many have looked too simply for cost to buy used and cost of repair. Parts are easy to come by and the ride quality is good. only thing I would say is to make sure it has locking rears for when you are off road.  If this is a dump truck you may look at Hendrickson HAS40K air ride for heavier speced axles

I use to swear by camelback until I drove a properly speced air ride dump truck. The pete I was driving with air track / Locking rears was much better than the camelback I was use to.  sure you could louse traction if you did not put the power divider in but if you locked in it would just walk thru just about anything. With macks auto power divider you never knew if the power divider was truly working or not and you still did not have a rear axle lock so at best you had 2 wheel power and 2 wheels spinning. with manual power divider and locking rears you have 3 wheels of power and only 1 can slip. 

But im getting off topic now. What ever you chouse just make sure you know what your buying but I suspect anything air ride will be better than the ryco spring suspension 

I wonder if these modern 34k axles are diffrent than say 40k axles.

If I recall right back In the R model days the 34k camelback was cast round tube and the higher capasity rears were welded square tube. 

what is the aux valve you speak of?

Most macks had 3 buttons

blue= tractor only 

yellow= parking (both trailer and tractor)

red= trailer air supply

If you are dropping to 90psi when you push in a button Id check the tractor protection valve or the brake buttons first (Primarily the yellow and red buttons)

that would be interesting to see how it comes out . the R model hood is going to be too narrow for starters. Maybe a modified superliner would be a better starting point but you would still have to modify to hood to meet the cowl to look anything like a truck

Very cool truck. Definitely Looks like it was set up for a heavy spec.

Those are older mack rear axles with newer style top load differentials. Never knew you could interchange them. If the stamped ratio is correct, that's a 7.00 ratio. You can check by lifting the rear up rotate drive shaft and count how many times the shaft turns to get the wheel to do 1 full rotation.

Obviously all those aftermarket air assist steering and filter housings etc are add ons. It definitely has character and somebody enjoyed improving it thru the years.

I use to buy my 1/14 scale tamiya cabs from shapeways. Not sure if you can still buy from them?

On 8/4/2024 at 11:13 AM, mowerman said:

Seems I’ve seen something posted on that right here on this website recently maybe six months or a year ago good luck… bob

I remember seeing a truck with wheelchare access and then years later, seeing a article about it.

I thought it was bisom but could be wrong

Yes very early 80s had 2 valve 300 hp

The 4v came out around 1983-84 if I recall

18 minutes ago, Geoff Weeks said:

Could you be thinking of Buddy Sombarts Marmon cabover?

I might be. Dan Bruno asked me that same question.

I'm trying to recall my trip to walcott  IA back in 2006?

Did bisom truck lines have a cruiseliner or superliner set up so a disabled driver could enter and exit the cab.

I know mike Harbison would know 

Thank you

39 minutes ago, mechohaulic said:

hope we get to see total picture of your lifting system! over head crane seems to be an understatement.  if you are going to reinstall those heads  based on picture, my recommendation is to pull ALL the studs first. or make dam sure those head stud holes are spotless. during the jiggle=jaggle of the heads being lowered ANY grit/crap in those holes  reaches those new head gaskets from those studs scraping bore before the heads seat in place. also the studs are supposed to be brought snug then backed off a tad. I used  from toolbox set of  wire wheeled /clean studs for such operations. which were removed once all engine studs were in place .

I used a service truck crane. To remove and replace the heads as 1 assembly. Made life very easy

Yes, I wire brushed all stud holes in the head. Pressure washed them and blow dry. All the stud holes in block were wire brushed and blown out after I cleaned the deck surface. 

All studs were wire brushed.

Lowered heads on with 4 studs used as guides until the dowl pins located them. Then I put all studs in hand tight and backed off 1/2 turn. All studs were same hight. Bolted down so far so 👍 

On 7/11/2024 at 5:34 PM, Joey Mack said:

the interior looks really nice, would love to see the whole truck.

https://youtu.be/WLYYPPEpJNA?si=aNrdX5jOmOGj8e_U

A CF686 denotes a 285 maxidyne.  my truck is a RS786 with the same engine.

A 300+ would be a CF612

Also a 285 hp usually had a 5 or 6 speed transmission as it was a high torque rise. where the 300+ needed minimum of 8 gears due to its shorter powerband

On 7/14/2024 at 1:25 PM, JoeH said:

Did you try just tightening the nut?

Not yet. Been busy. I will report back soon

6 minutes ago, Macman said:

Wow thank you all for your help.  I will try to find some of these parts.

My memory is fuzzy but I know the axle tubes from b models to R models are definitely different. For example a r model differential will not drop in a b model era housing. The spiders may swap over. Another thing to consider if your truck currently has camelback is just swaping in R model axles. It might be the same labor but you could get some 4:17 ratio and have a great highway speed now.

Just a thought

1 minute ago, fjh said:

Nope it’s metal on metal ! You could try putting a 11/4 wrench to it and try tightening abit! The top and bottom are two lapped peices!

Oh man.... and can you repair it in the truck or does the pump need to be pulled out?

45 minutes ago, fjh said:

Is it Ambac?

Yes sir. 

 On my B model i tried puting a 24/24 chamber on but its very tight to the rim. I'd assume  you would have the same issue.

To get 30/30 chambers you Probably need spiders and S cams off a R model to get the cans away from the rims. Possibly re clock them so the cans don't hit the frame rail.

That being  said I have never tried to swap b and R spyders so not sure it will inter change?

5 minutes ago, Joey Mack said:

how do you feel about it? it does sound good.  yes push rods rotate..  

Runs smoother than before. At idle it's much quieter. Knock on wood 

My injection pump has a leak at one of the barrels where it threads in. I recall someone saying you can remove the line, unthread the barrel and a oring is in there? Is it that simple?

This is on my 1977 285 maxidyne