Re: [MV] OT: HD Truck transmission swap basics (no MV - deletenowif you must)

Hi Mark,

My 85 GMC flatbed has a Detroit 8.2 turbo and it is geared so that it
runs about 3000 rpm at 60 mph. It has a 5 speed plus a two speed rear
also. I think a lot of trucks were geared that way with the 8.2 since
that engine needs to rev to make HP. From what I read after I got the
truck, they can run pretty much continuously at 3400-3500 rpm with no
problems at all. My engine is labeled for just over 200 hp at 3400 rpm
and since the truck weighs 12,500 lbs empty and has a GVW of 34,000 lbs,
it needs almost all 200 hp when cruising fully loaded at speed.

You could find a differently geared 2 speed axle, but you might be
looking for a while since a lot of the two speeds were geared in a
similar fashion. That would probably be the easiest swap.

The truck bellhousings are all SAE 2 or 3. The spicer 5 speed is a very
common transmission. I would go to a big truck scrap yard and tell them
what you want. They have a lot of cross reference books and just
simple plain knowledge.

However, in my case, I just decided that was the way the truck was
designed, so I use it in a similar manner. I run about 60 mph on the
highway, which really isn't a problem in Indiana, and let the engine
sing. It has lived about 150,000 miles like this so far, so I hope I
can eeek another 50,000 out of it or so before it needs a rebuild.

Oh, another thing - it is perfectly normal for 8.2's to smoke a lot on
start up since they don't have glow plugs. Plug it in if it gets below
40 degrees or so - or plan on using ether and killing all of the bugs
within 1000 feet with the smoke. (:->) My block heater burned out - so
bug kills are the norm at my place.

Did you move the truck yourself from out west?

Dave

[email]mark (AT) ehle (DOT) homelinux.org[/email] wrote:[color=blue]
> Hello, Folks -
>
> Sorry for the lack of MV content - delete now it you wish. Once again I turn to
> the only truckers I know for help.
>
> I have an '86 Ford C-8000 cabover single-axle tractor, 8.2 liter Detroit,
> 5-speed spicer and an Eaton 2-speed rear. It is an old Roadway city truck. I
> want to pull a 5th wheel trailer with it.
>
> It's a great truck but it spins over too fast on the highway, and I would like
> to put an OD trans in it. I don't want any more than 60-65mph, but at that
> speed, it is really turning fast. It doesn't have a tach, but my ears tell it
> must be around 2800-3000rpm. For those who might be wondering if the rear is
> shifting, it is indeed in high range.
>
> My questions to those among you who would know about these things is: What sort
> of transmission would I be best looking for to slow the engine down on the
> highway in this thing? And, is there a standard set of dimensions for these
> things such that HD transmissions all tend to bolt up the same way? I suspect
> there might be, but I don't know where to look up such stuff.
>
> I would rather change the trans instead of putting a new rear in it if I have a
> choice. I have in a past life spent a lot of time wrenching cars and light
> trucks, but I can't find basic info on heavy-duty trucks as far as what
> transmissions fit what bellhousings, what engines, rears, etc.
>
> Can some one give me a little primer as to what would fit this little tractor?
>
> Thanks so much,
>
> Mark Ehle
>
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