AMGeneral Posted April 22, 2019 Share Posted April 22, 2019 Howdy All, First post here, long time Mack lover, first time owner, I have a 1969 R685ST currently set up with a 14 ft Heil dump bed, 285 tip turbine engine, 38k rears with a CRDPC 92 front and CRD 93 rear diffs, both with 6.34 ratio. It has a TRDXL-1070 6 speed, 2 stick trans.... Anyone have any experience with this type of transmission? evidently it is an odd bird as most local Mack guys have never heard of it, and my local Mack dealer is about the same. I am not having any major problems, other than a "whine"? in 5th gear, high range. Fluid is clean and at the proper level, magnets are clean and no difficulty in shifting. Quote Link to comment Share on other sites More sharing options...
Macktruckman Posted April 22, 2019 Share Posted April 22, 2019 We have a couple of trucks with that type transmission and one truck I just pulled that transmission out of and replaced it with an overdrive transmission to try and lower my engine rpm in top gear. I love those transmissions in dump trucks. I think ours all have some gear whine. In the 30 years I’ve been around these trucks I don’t think any of them have been opened up for repairs. Triple countershafts and double tough. If it was mine I’d truck on if you like it. One of these was ran out of oil 20 years ago or more. Mechanic put a seal in it and refilled it with oil and it’s been more noisy than the rest ever since but it’s still never been apart... Lol 1 Quote Link to comment Share on other sites More sharing options...
terry Posted April 22, 2019 Share Posted April 22, 2019 They was also a direct version of that trans, they were only used a couple of years, then the went to the 107 six speed with the multi speed reverse. 5 spd. on the main and low-low, reverse and direct on the back box. terry Quote Link to comment Share on other sites More sharing options...
Macktruckman Posted April 22, 2019 Share Posted April 22, 2019 Terry that’s what transmissions we have. The direct. 107. Ours are not overdrive. Slow but so tough Quote Link to comment Share on other sites More sharing options...
AMGeneral Posted April 23, 2019 Author Share Posted April 23, 2019 (edited) 1 hour ago, Macktruckman said: We have a couple of trucks with that type transmission and one truck I just pulled that transmission out of and replaced it with an overdrive transmission to try and lower my engine rpm in top gear. I love those transmissions in dump trucks. I think ours all have some gear whine. In the 30 years I’ve been around these trucks I don’t think any of them have been opened up for repairs. Triple countershafts and double tough. If it was mine I’d truck on if you like it. One of these was ran out of oil 20 years ago or more. Mechanic put a seal in it and refilled it with oil and it’s been more noisy than the rest ever since but it’s still never been apart... Lol Thanks Macktruckman, It's not an a pronounced noise, just noticeable, even with hearing protection on in the cab. I guess I am a stickler for everything being "right" on a truck I drive, and since I use it for my part time grading business being down isn't a option. I guess this would be considered an OD trans then? It tops out at 42 mph in 5th low , and about 63 mph in 5th high. No speed demon, but it pulls my 20 ton dovetail and track loader with ease. I wish I could say it was in good shape when I bought it, but after going through both rears, new axle shafts, new u joints, new clutch and new king pins and bushings, it does OK now. I guess this isn't really my first Mack, I have owned several of the 673 powered military trucks so no stranger to the Mack name! Edited April 23, 2019 by AMGeneral Quote Link to comment Share on other sites More sharing options...
Macktruckman Posted April 23, 2019 Share Posted April 23, 2019 Yes sir I believe that is an overdrive transmission. We don’t have that exact transmission. Ours are all direct. 1 thru 5 on the main stick and reverse, low and direct on the second stick. If yours is what I’m thinking of it has reverse in the main stick... that correct? Quote Link to comment Share on other sites More sharing options...
AMGeneral Posted April 23, 2019 Author Share Posted April 23, 2019 (edited) 4 minutes ago, Macktruckman said: Yes sir I believe that is an overdrive transmission. We don’t have that exact transmission. Ours are all direct. 1 thru 5 on the main stick and reverse, low and direct on the second stick. If yours is what I’m thinking of it has reverse in the main stick... that correct? Yes sir, R and 1-5 on the main, like a typical Mack 5 speed, High and Low on the Aux, but you can only shift to High in 4th and 5th gears, R and 1-3 are locked out by an internal gate. Edited April 23, 2019 by AMGeneral Quote Link to comment Share on other sites More sharing options...
Macktruckman Posted April 23, 2019 Share Posted April 23, 2019 Yes that’s the one I was thinking of if I remember right it has a really tall overdrive gear, like .60 or something close. That’s why you can get to 63 mph on those 6.34 rears. I’m fixing up my personal truck right now. It has 4.17’s and had the direct 107 transmission and it wouldn’t go any faster than yours or quite as fast. I swapped in an Eaton 9LL with the.73 overdrive. I have not driven it yet but I’m almost finished. Gotta mount 8 new drives and put in kingpins and bushings tomorrow. How hard were your kingpins to get out? Quote Link to comment Share on other sites More sharing options...
Macktruckman Posted April 23, 2019 Share Posted April 23, 2019 You got the early R. Steel dash and the cab built for short people. Lol we have 2 of those trucks left. Quote Link to comment Share on other sites More sharing options...
Macktruckman Posted April 23, 2019 Share Posted April 23, 2019 Loved the steel dash Quote Link to comment Share on other sites More sharing options...
AMGeneral Posted April 23, 2019 Author Share Posted April 23, 2019 Just now, Macktruckman said: Yes that’s the one I was thinking of if I remember right it has a really tall overdrive gear, like .60 or something close. That’s why you can get to 63 mph on those 6.34 rears. I’m fixing up my personal truck right now. It has 4.17’s and had the direct 107 transmission and it wouldn’t go any faster than yours or quite as fast. I swapped in an Eaton 9LL with the.73 overdrive. I have not driven it yet but I’m almost finished. Gotta mount 8 new drives and put in kingpins and bushings tomorrow. How hard were your kingpins to get out? I did both by myself here in the shop( I worked for Freightliner as a Class 8 truck mechanic for several years) in about 5 hours, but my front axle is only a 10K unit. I did put an OEM kit in it from my local Mack dealership. I think it was $ 250 for the complete kit, bushings, pins and bearings. Quote Link to comment Share on other sites More sharing options...
AMGeneral Posted April 23, 2019 Author Share Posted April 23, 2019 (edited) 2 minutes ago, Macktruckman said: You got the early R. Steel dash and the cab built for short people. Lol we have 2 of those trucks left. Yeah, I bought it about 3 hours east of me , It is a bit cramped for me at 6' 1" , no power steering either, so you have about 1 inch between the A pillar and the 22 inch diameter steering wheel. Edited April 23, 2019 by AMGeneral Quote Link to comment Share on other sites More sharing options...
Macktruckman Posted April 23, 2019 Share Posted April 23, 2019 I believe I paid about the same for mine at Mack. I bought them a year ago probably. Just now getting around to it. Lol Quote Link to comment Share on other sites More sharing options...
Macktruckman Posted April 23, 2019 Share Posted April 23, 2019 I grew up in them. Mixer trucks. Hot, loud and ride awful. Love em. Lol. Can’t kill the things. The mixers didn’t have a passenger seat. So when I was a kid I would ride shotgun on a rotella box Quote Link to comment Share on other sites More sharing options...
Macktruckman Posted April 23, 2019 Share Posted April 23, 2019 I like your truck. Right up my alley. 1 Quote Link to comment Share on other sites More sharing options...
Lmackattack Posted April 23, 2019 Share Posted April 23, 2019 I have never driven the older 2 stick 5 speed with the over drive but all of the 2 stick 6 Direct 6 speeds had some sort of whine to them. some it was just felt in the stick others were more of a howl... the good thing is all of them were damm near bullet proof. I can only think of a few that needed bearings or something normal for wear items. 1 Quote Link to comment Share on other sites More sharing options...
AMGeneral Posted April 23, 2019 Author Share Posted April 23, 2019 (edited) Another picture of the truck in question Edited April 23, 2019 by AMGeneral 2 Quote Link to comment Share on other sites More sharing options...
Macktruckman Posted April 23, 2019 Share Posted April 23, 2019 I like it. Pretty good looking old rig. Especially considering it’s 50 years old this year. What’s the dozer if you don’t mind me asking? Quote Link to comment Share on other sites More sharing options...
j hancock Posted April 23, 2019 Share Posted April 23, 2019 BC-1 is a fine looking rig! Quote JimIt doesn't cost anything to pay attention. Link to comment Share on other sites More sharing options...
fjh Posted April 23, 2019 Share Posted April 23, 2019 11 hours ago, Macktruckman said: I like it. Pretty good looking old rig. Especially considering it’s 50 years old this year. What’s the dozer if you don’t mind me asking? I to Am interested in the make year of the dozer I have a similar looking unit in my back yard a 47 Oliver The trans noise you have was a common complaint and normal for them trannys nothing to sweat over ! 1 Quote Link to comment Share on other sites More sharing options...
terry Posted April 23, 2019 Share Posted April 23, 2019 (edited) 13 hours ago, Macktruckman said: Yes that’s the one I was thinking of if I remember right it has a really tall overdrive gear, like .60 or something close. That’s why you can get to 63 mph on those 6.34 rears. I’m fixing up my personal truck right now. It has 4.17’s and had the direct 107 transmission and it wouldn’t go any faster than yours or quite as fast. I swapped in an Eaton 9LL with the.73 overdrive. I have not driven it yet but I’m almost finished. Gotta mount 8 new drives and put in kingpins and bushings tomorrow. How hard were your kingpins to get out? You will love them 4.17's with that overdrive trans, should run about 65 at 1600 RPMs. I once had a DM dump with mack 12spd. and 4.17 rears, and engine would run to 2300RPMs, I could bury the 80 MPH speedometer. terry Edited April 23, 2019 by terry Quote Link to comment Share on other sites More sharing options...
AMGeneral Posted April 25, 2019 Author Share Posted April 25, 2019 Sorry it took me a while to get back, busy here lately, The dozer in the picture is a 1953 Caterpillar D4, 7U series with a Caterpillar 4A manual angle blade, direct drive, pony motor start with 6796 original hours. The picture was taken the day I picked it up a couple months ago, I use it in my part time grading business along with my Cat 941B. Quote Link to comment Share on other sites More sharing options...
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