so slow s1800 9 liter

[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.....??????????????????
thanks
adam

[opus]

I have a lot of experience with them....5 spds though. I dont know what the axle ratios were but I do know I had to bend the needle in the tachograph to keep the boss lady off my heels. 65 wasnt an issue. Great engine in my experience.

[adamanderr]

well its an 85 with 185k on it. 9.o na with an AT545. 32 footer so i assume that the 3/4 size. when i bought it it would only go 45 max..took off governor no change..
.so i figured if i switched the rear end ratio id be able to get a higher top speed on the flats knowing that itd be slow on hills but mostly i cruise cross country on interstates. the original rear ratio was 5.57 and it had split wheels. well my junkyard buddy hooked me up with a deal......a complete axle assembly.with only 20k miles on it...leaf springs air pots new budd wheels brand new rubber on all four wheeels all for 1500.
so i felt it was an awesome upgrade. safer more modern super low mileage etc all for 500 dollars more than the replacement rear gear for my original pumpkin would cost.
oil change all new filters replaced gaskets to stop oil leaks. the other difference besides axle ratio is the outer diameter of the tire is more modern standard..24 i believe i need to go check.
also i baby it. i go low rpm on hills and dont push it. i keep it below 27-2800 and since have owned it not gone over that religously...
so i dont know whats up. my uncle is a big rig mechanic albeit a grumpy one who cant be talked into working on it even for mony but he did go for a fifteen minute test drive (not on the highway but rural without any big hills) and says it sounds good and seemed to be running good

still has 22.5 tire in front and 24s in rear so it looks like a gasser hot rod

also just did a mileage check and for a trip thru vermont with moderate terrain we go 7.5 MPG

i feel i have a serious issue with this thing im constantly getting honked at and flipped off for being so slow

[opus]

We drove them hard, kept them wound up well. I dont think you are going to get what you want by babying it. I know where you are coming from but that is just my experience.

[adamanderr]

so should i go over 2800rpm.is that safe.
also often its floored and still wont even go over 2800.
often when its gets close to going over 2800 the tach needle starts to bounce.... whats that all about
thanks

[opus]

It should be governed around that I do believe. That's all you are going to get. Don't expect to get into a hill with low rpms and expectbit to pull the hill. Make sure it's wound tight at the bottom and what you get is all you are going to get.

[wmah]

Unless you changed out what you would have to get the speedo to read right with the rear end you put in there it may still read that lower speed that it did before.

Get a gps unit and go out and see what it does.

[dunnwright]

Sounds like a great deal on the axle!
Diesels can run pretty ramped up just fine
You just have to make sure to monitor your exhaust temps
check out "neverenufhp" on this board

[NewSkewlHauler]

I checked Gear Vendors for an aux trans unit...that was 9 months ago. They don't have them (or didn't) for Allison AT & MT series transmissions. Wish they did!

[NewSkewlHauler]

NC, unless I missed something in the article you referenced, they said that a TH475 with a GearVendors was similar to the current 5 speed Allison backing the 8.1L GM motor. I checked the Gear Vendor site and they mention the usual transmissions (TH350, and some of the electronic 4 speeds). I didn't see anything, unless I missed it, for the bigger AT & MT Allison trans.

I have an AT 545 behind my 8.2L Detroit. If I somehow missed something, let me know.

[kotflb]

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.

[adamanderr]

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

[fishphart]

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.....??????????????????
thanks
adam

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 www.industrialdiesel.net 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]

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.