Better highway speeds

[DIRT]

Hello all,

Just got a 1984 IHI. Thomas standard bus body. 9.0 liter v8 deisel. 5 spd manual. I think trans is a Clark. I would like to cruise 65-70 on the open road without engine screaming at 3k rpm. Need suggestions for either better suited mt, 3rd member, r&p or complete rear.

Jim

[family wagon]

Originally Posted by DIRT

Hello all,

Just got a 1984 IHI. Thomas standard bus body. 9.0 liter v8 deisel. 5 spd manual. I think trans is a Clark. I would like to cruise 65-70 on the open road without engine screaming at 3k rpm. Need suggestions for either better suited mt, 3rd member, r&p or complete rear.

Jim

Can you find numbers for the rear axle assembly, 3rd member, etc? Dana (for example) publishes parts lists that show all the gear options they had available for a given axle. Having a chart of the readily available options would help narrow the search. If you can find a number for what you already have, that could help lead to the right section of such a table.

[DIRT]

Still trying to ID assemblies on bus. We will crawl under and look for markings tomorrow. Thanks.

[Kubla]

call the international dealer closest to you with your VIN, they can tell you what rear end it came out of the factory with, information you need to buy another differential

[rvingoffgrid]

Make certain you have enough horsepower to pull taller gears. Or you'll be very disappointed when you can't reach your desired speed except down hills

[rvingoffgrid]

Another thing is some manual trans can be made into over drive units by simply replacing a couple of gears but not all might see if your trans can be converted

[Tango]

A "Brownie Box" can be added to most manual trannies that incorporates some degree of overdrive as well as resulting in much closer ratios throughout the range.

There's plenty of info out there on them. Just saw this the other day. It relates to a '78 GMC truck, but Browne-Lipe units are most common on diesel big rigs.

https://www.youtube.com/watch?v=u_FIYFOjNYg

The only draw back I have heard from folks who have installed them is that they do require double-clutching, but that practice has been common on large, manual trans vehicles for at least a hundred years.

[cowlitzcoach]

If it were me I would run what you have as is until it dies.

The 9.0L is an orphan that IHC would just as well forget they ever built.

It was a cheap upgrade from the gas engines of the time and a big step down in price from the DT466. Advertisements suggested the upgrade to the 9.0L would pay for itself in fuel savings within just a few thousand miles. Unhappily for all those that went for the cheap upgrade, they were sadly disappointed in how poorly the engine performed.

If you try to turbo the engine you will blow the bottom end out of the engine--it doesn't have enough on the bottom end to support any real HP upgrade.

Don't lug it for the same reason.

If you really like your bus and the way it has been converted, run it the way it is but start shopping for a donor bus with the engine you would prefer. When the 9.0L dies you will then be prepared for a power package swap.

Good luck!