dek1581 Posted August 12, 2015 Share Posted August 12, 2015 I was recently looking at old brochures on f models and although they had maxidyne 675 and 676 paired with maxitorque 5-speed, the mack etaz 673a (300 plus) was paired with 10-speeds or better. based on the horsepower and torque ratings and rpms, it seems like the 300+ was a higher revving engine(correct me if I'm wrong). why was this and is it possible to pair the 300+ with a maxitorque 5-speed and if not, why? Quote Link to comment Share on other sites More sharing options...
alex g Posted August 12, 2015 Share Posted August 12, 2015 I own one so it must be trueSent from my SM-G386W using Tapatalk 1 Quote Link to comment Share on other sites More sharing options...
kscarbel2 Posted August 12, 2015 Share Posted August 12, 2015 By intention, the 300 Plus was designed for a multi-speed transmission (9 or more speeds). But having said that, we had customers pair them with Maxitorque 5-speeds and drive them thousands of miles, completely satisfied with performance, fuel economy, ect.Operators do need to watch their pyrometers in "extreme" operating conditions. 2 Quote Link to comment Share on other sites More sharing options...
dek1581 Posted August 13, 2015 Author Share Posted August 13, 2015 is the ETAZ 673A the 4-valve upgrade that was introduced around 1984 or was it earlier in a 2-valve version? Quote Link to comment Share on other sites More sharing options...
b61mack Posted August 13, 2015 Share Posted August 13, 2015 2 valve, don't think they made a 4 valve ETAZ 673 Quote Link to comment Share on other sites More sharing options...
chief doug Posted August 13, 2015 Share Posted August 13, 2015 i used to repower 237's with 300's. mack said that was the highest hp to put on a 5 speed Quote Link to comment Share on other sites More sharing options...
Joe Ditchkus Posted August 13, 2015 Share Posted August 13, 2015 I do not believe it is the torque range lacking on a Maxitorque 5 speed trans it is the amount of gears when used with a ETAZ 673 that was designed for multi speed trans such as 9,10,12,13 0r 15 speed. The ETAZ 673 was not a constant torque engine as the 237 and 300 Maxidyne was. 1 Quote Link to comment Share on other sites More sharing options...
Superdog Posted August 13, 2015 Share Posted August 13, 2015 i used to repower 237's with 300's. mack said that was the highest hp to put on a 5 speedthere were 2 versions of the Maxitorque 5 speed,the ones the put in 6 cylinder trucks were the TRL1076 and TRL1078 which they put behind the V8 Maxidynes. 1 Quote Link to comment Share on other sites More sharing options...
Outbehindthebarn Posted August 14, 2015 Share Posted August 14, 2015 One on ebay:http://www.ebay.com/itm/1981-Mack-Superliner-30-ton-wrecker-/221850037193?forcerrptr=true&hash=item33a74aebc9&item=221850037193 Quote Fun is what they fine you for!My name is Bob Buckman sir,. . . and I hate truckers. Link to comment Share on other sites More sharing options...
Superdog Posted August 14, 2015 Share Posted August 14, 2015 One on ebay:http://www.ebay.com/itm/1981-Mack-Superliner-30-ton-wrecker-/221850037193?forcerrptr=true&hash=item33a74aebc9&item=221850037193That one is a RWS786LST so it's just a 300,if it had a 300+ it would be a RWS712LST 1 Quote Link to comment Share on other sites More sharing options...
Outbehindthebarn Posted August 14, 2015 Share Posted August 14, 2015 That one is a RWS786LST so it's just a 300,if it had a 300+ it would be a RWS712LSTEveryone wants their 300 to be a Plus+... 1 Quote Fun is what they fine you for!My name is Bob Buckman sir,. . . and I hate truckers. Link to comment Share on other sites More sharing options...
dek1581 Posted August 14, 2015 Author Share Posted August 14, 2015 hey superdog is there a chart somewhere that shows models and cross references with engines and trannys? Quote Link to comment Share on other sites More sharing options...
j hancock Posted August 14, 2015 Share Posted August 14, 2015 Everyone wants their 300 to be a Plus+...Some people have tried to pass off a 237 as a 350 in truck ads.... Quote JimIt doesn't cost anything to pay attention. Link to comment Share on other sites More sharing options...
david wild Posted August 22, 2015 Share Posted August 22, 2015 I thought that the 300 was a Maxidyne and the 300 + was a Thermodyne, Maxidyne had 5 or 5 with low stick and all Thermodyne has multi gear trans.????? anyway back when we drove them that is how it was explained to us. Quote Link to comment Share on other sites More sharing options...
b61mack Posted August 23, 2015 Share Posted August 23, 2015 I think if you pull a 300+ down to 1200 rpm with that much fuel the exhaust temp. would be extremely high, I know my 300+ goes up to 1000 degrees when I downshift mine at 1500 rpm. 2 Quote Link to comment Share on other sites More sharing options...
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