Rawze.com: Rawze's ISX Technical Discussion and more

Trying to buy a truck and this Kenworth caught my eye. It has an IXS15, 500 HP, 18 speed manual transmission, with a ratio of 3.42. what's your opinion on this truck?

It is geared too fast unless you plan on hauling ass! IMO, 3:55’s if your a 65mph guy, 3:70’s if you run 60-63, 3:90’s if you run 57-60. Maybe if you could pick it up cheap enough you could swap out the rears with a lower ratio drop in?? Just an idea.

I’ll be honest I never understood the point of an 18 speed for OTR work?

I like 18 better for the hills. That’s my favorite trans. Just my opinion.

Direct drive with 3.42 is not a deal breaker.
Oil burning carbon packed pistons, non updated fuel pump, low oil pressure at idle are deal breakers.
Without a outside mechanic removing valve cover to inspect cam and fuel pump I would not consider it unless there is $30,000 dollars of cash left in your pocket after the deal.
I have a 2013 KW T800 with isx with 350,000 miles and very aware of this situation. I would purchase differently if given another chance with the true and real information learned here.
I burn 1 gallon every 3000 miles, updated oil pump, rolled new main bearings, installed by pass oil filter, updated fuel pump plungers and rollers. Also Re-sealed front structure because of oil leak.
As Professor Rawze would say, a true cry baby. But she’s paid for and looking to inframe in the future with all the upgrades learned from others.

(02-08-2019 )Soulreaver0102 Wrote: [ -> ]I like 18 better for the hills. That’s my favorite trans. Just my opinion.

Once you get out of the low range, a 13 and 18 are identical., just mentioning it for those who may not know.

(02-08-2019 )Elmuchotazz Wrote: [ -> ]Trying to buy a truck and this Kenworth caught my eye. It has an IXS15, 500 HP, 18 speed manual transmission, with a ratio of 3.42. what's your opinion on this truck?

throw the 3:42's in the garbage. no money in those crappy spec'd liner-fretting rears.

i would run as fast as I could away form a 500hp 18-speed that was spec'd to abuse the engine in the lower RPM ranges. - i see liner fretting issues with it by the time it gets 650k miles or so,.. just the trend they tend to follow anyways.

is the liner fretting bc he has that low of a gear ratio where all the gears would be turning even faster then say 3.90 rears?
What is your ratio on your truck Rawze?

Also my oil pressure gets lower when I idle and then goes up when I am driving or I rev the engine.

(02-08-2019 )flatbed94kid Wrote: [ -> ]is the liner fretting bc he has that low of a gear ratio where all the gears would be turning even faster then say 3.90 rears?
What is your ratio on your truck Rawze?

Also my oil pressure gets lower when I idle and then goes up when I am driving or I rev the engine.

He’s saying running in the top gear at 60-65 will turn too low of an rpm, lugging the engine, causing vibration, thus fretting liners. I have read up in this because I have one of those spec’d to abuse the engine in the lower RPM range trucks he’s talking about. I always run in a lower gear, keeping me in the 1400 and up range. I’ll put it in overdrive sometimes if I’m light and out west on flat ground. If this were my old early 90’s outlaw days I have have a bad ass triple digit truck the way this is geared. I could put it in the big hole at 80+ mph lol.

Like JMBT says, a truck with 3.55 rears is the the ratio you want if your a 65 mph guy.