ozrad7

Name: mack r688rst (1984) Date Added: 30 March 2010 - 03:06 AM Owner: ozsrad7 Short Description: 84 r688rst, e6 2v 350 econodyne fitted with jacobs engine brake, 10 speed maxitourque, 55000 lbs camelback rear end, aluminium bullbar by barworld cranbourne victoria, View Vehicle

The valve is inside the right hand chassis rail just above the front drive axle

Im guessing you truck is the same as mine so here are some pics of the valve and supply button, i dont know weather all macks are the same but i have to push this in to supply the trailer unlike my old bosses mercedes where there was always air at the duomatic at the rear.

Do you mean brake air? I had the same problem on my 84 until i pushed the trailer supply button on the dash, I assumed the air would already be there as it was plumbed up for a tag trailer when i bought the truck. If thats not the problem i will go take some pics of how mine is setup for you.

I thought about going a mechanical E7 but have been told they are pretty rare to come by in oz,. Did you use your original mounts or do you use E7 mounts on a E7.

G'day to all, my 84 R688RST could use an overhaul on the engine and transmission, It is still working everyday doing tipper and truck and dog work but the engine is breathing heavy and leaving a few drops of oil from the breather and the transmission makes a very loud whining noise on a hard pull up hill, so loud that you cant here the turbo or engine over it and is getting hard to shift into the 5th gear position without grinding a tiny bit unless you double clutch it in which it goes in no drama,every other gear goes in fine without clutching. It is currently an E6 350 econodyne with a t2070 12 speed and it still runs and pulls really well but i am worried one day something may go bang. So i am thinking about buying a complete ch/chr from the 90's with a 400+ E7 and 18 speed from the damaged/salvage auctions and fitting it all up in the r model , i figure i will save a fair bit of money going this way and improving the perfomance of the truck going this way rather than rebuilding the current setup, i may even get a little bit back by selling off what i dont use as well as the current engine and trans still running. The only thing i am concerned about is will it fit without too much mucking around and how complicated is the computer setup on a ch/chr as in will it require every single sensor and instrument from the donor to work. If anyone out there has done this before or has knowledge or worked on these models before I welcome your opinions and advice,thanks.

mine was only 4 inch so it fitted between the rail and fuel tank , when i decided to do my stacks i wanted 5 inch but i mesured everything up i found it wouldnt fit.if it was a prime mover it would becuase the y piece could of gone above the rails behind the cab wich would be a better setup as mine is mounted directly in the muffler there is a split second delay between the stacks when i put the foot down. , what gearbox are you using because my mack box is the perfect shape on the drivers side for the muffler to be mounted beside it.

i mounted mine off the cab because my cab has a air bag under it and made my own y piece from 2 90 bends cut down the middle and welded together, its cheaper and you can make the y suit your application by making it angle up or down instead of being flat.

i just put twin stacks on my r 688 so here are some pics of how i did it, it may not work in your case but it might give you a better idea of how to go about it, i didnt have a lot of room to work with either but managed to make it work but discarding the original exhaust mounts and making my own. i would be lucky to have 10mm of clearance going over the tanks and have not had any dramas.

here are the pics of my bullbar mounts, i also took a look at that web link, i wonder if anyone down under make the quick release eye bolts they use . my bar cost me $3500 the guy who made it starts with a set design and modifies it to the customers specs thats why the bottom kick rail is angled up and back at the ends because i didnt like the road train look of the straight rail with the end uprights protruding downwards, it also gives me a slightly better aproach angle for the onsite / off road work i do . in my personal opinion my bullbar is one of the best ive seen on a r model, others ive seen are either a full heavy road train 5 post style or a big pipe rectangle type which i think look awful . a bullbar also squares off the looks from the front almost making it look like a superliner from a distance, it really does completly change the looks as you will see in the pics with the bar down and up. if i can help out with more pics or anything let me know.

the snorkle setup no my truck is original mack but i believe they are an australia specific setup to keep the intake up out of the dust, we must have more dust here than you guys do so maybe you could one through mack otherwise i think donaldson make the same thing, they may even be the the original supplier to mack australia.as for the gaurd do you mean the exhaust gaurd or the bull bar on the front.the exhaust guard has a clamp that goes around the pipe with captive nuts in it the gaurd bolts to, the bull bar has a fabricated cross member that either attaches to or replaces the original one that have two peices of steel each side of it that the lower bar mounts fit into with a single bolt each side to let it fold down so the bonnet can be opened, when it is up it is held by two 7/8 eye bolts through the front into nuts welded to the cross member.i will take some pics and post them for you so you can see what i mean.

i finally got around to taking some pics of the stack mounts i made.i hope they help, as you may or may not see i dont have much room between the cab and the tipper body so the stacks are slightly on the side of the cab with a 180 degree style gaurd and my mount is attached to the existing croos member via steel plates welded to them. if i had the room i would have mounted it to the chassis with u bolts like the original cross member.

I will try to take some pics tommorow if i can find my camera.

i just put duel 4" stacks on my 84 r 600 tipper,my truck only has 3" between the back of the cab and the tipper body so the stacks are mounted beside the cab. the muffler was already mounted beneath the cab.i used 2 90 degree bends to make a y peice and 3 90's each side and ran the pipes outside the rails the up over the rear of the fuel tanks.my stack end only a foot above the cab and is very loud,espeacialy with the window down.

that superliner in australia would be worth $30-$40,000 if it had a e9 in it add $10,000 or more

this question may only make sense to aussie members but i am thinking about buying a two axle dog trailer to go behind a 84 2vh 350hp r model tipper.As a tandem it gets along well enough with 12 ton on it but will i kill it with the trailer towing another 13 or so.i have seen later model value liners which i assume to be 350hp 4 valve heads pulling dogs but are they killing their trucks or do they do it easy., i have never been able to talk to these blokes as i have never worked with them. I have been told by a old school trucker that a 350 mack is the equivelent of a 400 cummins, is this true or a old wives tale.

I just had the same problem with the 10 speed in my r model,turns out the circlip in the bottom of the spitter cylinder had broken and the loose piece nicked the large o ring on the piston.cost me $15 to repair and only had to remove the cylinder which near on sticks out the rear of the cab on a r model.now shifts perfect.

yeah im not getting oil from the tanks anymore so whats in the system would be built up sludge i think, when you put the metho in the system how long do you leave it in for before draining the tanks? a day or two or a couple of hours and repeat till it starts coming out clean?. My local truck work shop told me all they could do was remove all the lines and tanks and clean them seperatly to which i said dont worry about it.

Thanks for the input spud, i have decided not to worry about the wheel base as it would mean losing the tool box on one side and a new hydraulic tank on the other, will definently shorten body though. I like that superliner of yours , i wish i had of held off buying the econodyne till i found one myself.

its been like it since ive owned it so 9 months and for how long before that is anyones guess but the drums and linings were replaced before i bought it, i did have to replace a slack adjuster on the rear drive as it would loosen itself off within a day or so.I just put a new compressor on it and there was a lot of oil in the air system which seems to have cleared out of the tanks now so maybe the lines,valves, ect. all need pulling apart and cleaned out. I need to do the wiper motor aswell as it wont work until the engine bay warms up. I didnt want to touch the brake system until i was sure i had a problem.

Im just wondering if it is normal for there to be a delay between when the front drive brakes lock up and the rears do? mine seem to take a good 1-2 seconds or depending on adjustment dont lock up at all. I only noticed this because sometimes part of the load gets stuck in the tipper body and needs a bit of a jolt to get it out. The truck is a 84 r688rst with 55k rear end.

g,day all i have a 84 r688 tipper i use for hourly hire work and was wanting to know if the wheel base could be shortend. I need to either replace the body or repair it at witch time i would like to take about 400mm of each end to reduce the capacity as i dont see why i should cart 13m2 and get paid the same as the ud's i usually work with who can only take 10m2. I have looked at the rails and in front of the pedestals it looks like it is already drilled to accept all the bolt ons about a foot or so closer to the cab.Has anyone done this before because i would hate to get everything undone only to find the holes are 1/2 a inch out or something stupid like that. I realise i will need to shorten the centre drive shaft and brake lines ect. but it would be worth it to improve the turning circle and lower the tare weight , at the moment it tares off at 10860kg's.