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Old 11-26-2010, 08:56 PM   #11
Join Date: Sep 2006
Posts: 105
Year: 92
Coachwork: ward flat nose
Chassis: international
Engine: dt466 mt643 air ride
Rated Cap: 84
Re: so slow s1800 9 liter

First thing you need to do, as suggested earlier, is get a gps and see what your real speed actually is since you've already changed the axle ratio.
With your rpm and tire size you should be north of 65 mph. If you gps says your running below 65mph, I would suspect your transmission is slipping too much. You may be able to cure your problem by changing just the Torque Converter to a hardier one. All AT545's slip some b/c they have no lockup gears like the MT643's do.

But b4 you go through all the trouble of changing the TQ or transmission, try flushing the trans and TQ fluid at one of those quick oil change places. A transmission flush will get all the old fluid out of the trans and TQ and replace it with new fluid.
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Old 12-13-2010, 12:06 AM   #12
Join Date: Aug 2007
Posts: 137
Re: so slow s1800 9 liter

i should try the trans flush and put in a new filter. the only way i know how slow im actually going in relation to the speedo is the"your speed is" signs the cops put out. i have full fluid and a bunch of lucas non slip but i guess i should just try to change it all out any way. to whomever suggested the gear vendor thanks. never heard of those, am interested but the real reason i did what i did was to gain an axle housing uprated springs and brakes along with more modern wheels budd vs split rim and larger circumference tire. thanks guys
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Old 09-16-2011, 04:01 PM   #13
Join Date: Jul 2009
Posts: 46
Year: 1987
Coachwork: International
Chassis: International
Engine: International 6.9L diesel
Rated Cap: 71
Re: so slow s1800 9 liter

Originally Posted by adamanderr
does any one have this experience with their 9 liter. its an b5 thomas body 32 footer witha nine liter ihc and an AT545. i used to have a 5.57 rear end and it was dead slow so i put in a 4.44 and it still cant do over 50 on flat ground 2800 rpm ( max safe rpm ive been told by many bus mechanics). its an absolute old dog on ANY hill. only has 185K on the engine and has been well cared for. whos got a nine liter and what do yall think. it took me a week to drive 2000 miles at an average highway speed of 45 mph. at 7.5 mpg.....??????????????????

it all depends on how WELL the vehicle was maintined for those 185K miles. A simple compression check will tell you alot.
it may have enough compression to start and run but be blowing most of your air and fuel right by those tired olde rings and valves.
FLEET maintained is a joke...especially when it comes to buses. Tractor trailer "fleet maintined" is a joke too. They know MONTHS in advance when they are going to sh_tcan some vehicle and dont put a dime in them. It's a business for them, not a dream or hobby and its a cuthtroat job too.
To do an "In Frame" , not removing the engine from the vehicle, is one definite and doable option. yank the head and send it out to be rebuilt. Drop the pan and remove the pistons and re-ring them. While doing so, check the cylinders for straightness.
If you truly have a 9 liter engine, you should be smoking up those hills.
Commercial semi's hauling 55K weight have only one litre more than your engine.

Industrial Diesel Inc in Fort Worth, Texas 1800-323-3659 is a very inexpensive and reliable source for all diesel engine parts.
Get yourself the mechanix guide for that particular engine. A GOOD torque wrench and "skin" that thing yourself.
Good tool sets are available on ebay for a song compared to new cost.
fishphart is offline   Reply With Quote
Old 09-21-2011, 12:18 PM   #14
Join Date: Jul 2009
Posts: 46
Year: 1987
Coachwork: International
Chassis: International
Engine: International 6.9L diesel
Rated Cap: 71
Re: so slow s1800 9 liter

Originally Posted by bender477
Dont forget that the absolute final drive ratio depends on the size of the tires , check the specs and make sure that tires are the o.e size and that nobody swapped them out for some smaller sizes to save a buck . this will alter the top speed drastically as well as throw the speedo reading off .
Man do you have that right!!!! Totally skipped my mind. I swapped out the "metric" style tires on my Freightliner for the traditional AMERICAN 11R22.5 size and increased my speed and increased the mileage (slightly) when cruising.
The AMERICAN size 11R22.5 were about 2 inches taller.

Funny how the new buses have those tiny pickup truck size tires. Easier to mount and dismount by untrained personnel.

It was a great day when I learned how to m ount and dismount my own 11R22.5 tires. Thank you YOUTUBE. Bought two moderately expensive tools on EBAY and spent a vcouple hours one day yanking off the olde and installing the new.
Saved a $50.00 mounting charge for eight ( new Micheline's. Got the tires on-line and saved a bundle there too.
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