HK Trucking

http://s80.photobucket.com/albums/j188/HKJ...=Picture093.flv

Turn up the sound before viewing! Driving my RB 688s http://s80.photobucket.com/albums/j188/HKJ...=Picture094.flv

I'm sure they're referring to the fact that it has a ENDT676 285(283) h.p. engine with turbocharger and a tip turbine intercooler. Just more B.S. from someone who's trying to exaggerate the specs of a truck they're trying to sell for big bucks.

See this thread: http://bigmacktrucks.invisionzone.com/inde...?showtopic=1003

Extremely beautiful! Looks just like it probably did in 1964. I believe Superdog is correct about the 5.73 ratio. I had a couple of DM 690's with 5.73 rears on 10.00x20 with T2070 7 speed which has an overdrive which is comparable to 5th hi split in a quad box. They would run 68 mph @ 2000 rpm, but on your 11-24.5 it'll be a bit faster, also your engine runs 2100 rpms, so that'll give a little more speed too. Might want to check with your local Mack Dealer, the 5.73 gears may not work in your current 7.49 carriers. Could be a difference in the pinion housing due to the depth being different due to the different diameter of the ring gear. Perhaps you could exchange the present carriers for 5.73 carriers. I have purchased exchange rear differentials from Weller truck parts in the past. Next day service, they deliver a rebuilt & pick up the old one. Can find their phone # if you need it, otherwise they advertise in most of the truck sale magazines. Herb

Auto Trans = Scrap iron price.

You guys all missed the most important factor here! Thankfully, it's not a Mack.

The ratio is stamped in the carrier housing, on the flat area on the front side to the bottom right. If yours is on 11.00x22 rubber it prob. has 7.49 ratio, that was common in lots of B61 10 wheelers back then, & would give approx 52-54 mph at 2100. If it's on 11.00x24 rubber it may have 8.24 ratio, that would also put you in the same ballpark as far as mph. 6.34 is an available ratio for the crd 112 & 113 carriers (which I'm just assuming here is whats in there) and we had a truck with that ratio on 11.00x22 which if I remember correctly was capable of about 65 mph @ 2100 rpm. Also, if you go to the Eaton Fuller Roadranger website there is a ratio/mph calculator there to determine road speed @ a given rpm depending on trans high gear ratio, rear axle ratio, tire size etc. Hope this helps, looking forward to seeing the "completed" pics. Herb

My personal opinion: AIR RIDE SUCKS! I had 1 dump truck with air ride, got rid of it real quick. Spring suspension is the ONLY way to go. A B model with air ride is no longer original. Again, this is my personal opinion.

The 44,000 lb rears are rated at 44,000 lbs load capacity for the tandems. Most of these were on camelback springs, but I've also seen some on solid walking beam suspension & beam over spring suspension. When I lived back east in CT, I remember seeing some B81SX's with the 9.02 ratio, these were usually equipped with 65,000 lb. rears (CRD(P) 95 & CRD 96 carriers) which have the 8 bolt 2 piece axles, on 24'' rubber & were heavy dump trucks for short haul work in town or on the jobsite. A ratio that low is definitely not conducive to highway operation. The B81 I was running at the time originally had the 65,000 lb rears on 24'' rubber with 8.14 ratio and if I remember correctly with the TRQ 720 quad box in 5th hi @ 2100 rpm it topped out around 52 - 54 MPH. Later I swapped in a set of 55,000 lb rears out of a H81 with 8.24 ratio, really didn't notice the slightly lower ratio (never corrected the speedometer drive, so it still read the same!)

Hmmm.............. Mack sales up 12%, Volvo sales down 6%. Why don't they just stop selling those P.O.S. Volvos in the U.S. & just sell REAL trucks (Mack) from now on?

Those appear to be 44,000 lb. Mack rears, the 6 bolt 2 piece axle setup pictured was used on those. Should have CRD(P) 92-front & CRD93 -rear carriers. the 2 piece axles were used on the 44k up til about 87, when they changed to a 1 piece 6 bolt axle. You're right, those wedges do appear to be homemade.

C'mon now--------------Exchange a triplex (or any manual trans) for an automatic????? WHY, WHY,WHY.

How would a 20 speed (I assume you mean a quadruplex) get annoying? What will really be annoying is having a 5 speed in a dump truck & trying to start off in soft ground with a load on! I can smell the burning clutch facings all the way from here! Not only that but you'll lose top end speed because the quad box is a double overdrive trans & the TRL 107 5 speed is direct in high gear. The quad box is direct when the main is in 4th & the compound in direct. The T 2050 5 speed is an overdrive trans, but there again you'll have no deep reduction to get it moving off road or on a hill. In my experience if you multiply the lowest gear ratio in the trans X the rear axle ratio, the number must be at least 60.0 in order to have acceptable startability off road. This calculation is for a truck on 10:00x20 or 11R22.5 rubber, larger tire sizes will require still deeper reduction( a higher number for overall reduction. As far as power steering? Just think of all the people who pay good money to go to a gym & work out. You'll get a work out for free. Just kidding , manual steering ain't easy, but when I was a kid that's what I learned on & then power steering seemed like heaven.

Too bad they didn't use a Volvo, it's a shame to waste a Mack, when there's so many "brand X" p.o.s. trucks out there. BTW, the pencil pushers who wrote the story called it an "RM". Looks like a "DM" to me.

Ouch!!!!!!!!!!!!!

That 3208 is probably worth a lot of money now. The price of scrap metal is way up.

For whatever it's worth, my 91 RB 688s with a E7 400 is equipped with a factory installed boost guage & runs 35 lbs boost on a hard pull in cool weather, tapers off to about 32 lbs on a hot summer day. Don't have the boost spec handy for that particular setup, maybe Superdog would know.

Theres a dead short circuit somewhere between the dash switch & the jakes, or possibly internally in the jake brake. Try disconnecting the wire from 1 jake at a time & turn on the switch, see which one either does or does not blow the fuse, also try disconnecting wires from both jakes & turn on the switch, if the fuse still blows then the problem is in the wiring between the dash & the jakes or in the switch on the pump. If it turns out that 1 jake is shorted internally, pull that valve cover & check for a pinched wire in there between the jake spacer & the jake brake unit, if that checks out then the problem is in the jake unit itself. BTW, a jake brake should also have a switch on the clutch pedal to shut off the jake when the clutch is disengaged.