8LL swap

[ster1]

Hi folks,
I’m driving an ‘85 1954 DT466 AT545, like a lot of us, I’m trying to convert to an Eaton. I’d prefer an RTO, of course. Anyway, at the yard I keep my truck is a Roadranger than I can have cheap. I’m going to look at it today. It came out of a dump truck, so I’m assuming it’s an 8LL. While the LL part is nice, I’m much more interested in overdrive. Although a 1.00 top gear with a manual clutch will probably get me 65 MPH fairly consistently, If I’m going to the trouble, I want the OD. I believe there are some LL models that have OD top gear, but I’m not sure about that. My first question would be, if this one is a straight 1.00, can it be converted to OD, like .75 or .80 somewhere in there? My next question would be, what do I have to look for as far as input shaft goes? Are they all the same, or is the pilot bearing boss different sizes?

Thanks for the help!

[cadillackid]

might be easier just to gear up the rear// you have 10 speeds so you could go to a bit taller rear end and have plenty of gears and also your top speed at lower RPMs as well.

[Booyah45828]

8ll is a nice trans. It'd be well suited to a 466 in a school bus, as it has enough gear options, but not too many as to have a lot of overlap with the 466's comparatively wider power band. The low slot would give you a nice crawler gear if you're ever in a position to need it.

I'm in agreement with you though, that I'd keep your current rear axle and opt for an overdrive. If you're already wide open at 65, an OD will keep that but drop the rpms into something more comfortable for cruising.

The 8LL can be had with or without OD, and I've seen both enough that neither option would be considered more common then the other IMO. The 7/8 slot in the shift pattern is flipped if it does have OD. The only thing you need to know about it is that right and back on the shifter will always be Direct. Always. What changes is your right and forward slot, with it either being underdrive and 7th gear, or an overdrive turning it into your new 8th.

The tag should tell you which trans, OD or not, that you have. To switch a non-od to an od would require changing a gear on the main shaft and swapping in different countershafts. I think I was told once that you can get the 3 different gears seperate and press the 2 off the countershafts to convert it, but I've never done it and memory can be hazy.

It might just be easier to find a OD unit then converting what you have.

[ster1]

Thanks guys, turns out, it's a super 10, not 8LL, as I assumed. The story is, the guy bought this trans for a valve (splitter cylinder probably) on the rear housing, and he's more or less giving the trans to me (without the cylinder). I know nothing at all about the super 10. The real crappy thing is, the data plate is gone, so I don't know exactly what I'm dealing with. Guessing its an RTO16610, or something like that. I can't find what the bell housing is. I believe the 466 is an SAE 2. It has an AT545 on it now, which is definitely SAE 3, and there's an adapter in there, so I'm kind of guessing on the SAE 2 thing. Lotta guesswork going on here

[Booyah45828]

Bummer on the tag. It will take some work to figure out what you truly have without it.

Super 10 was a 10 speed but the way the ratios are, you shift it different. They were all OD IIRC, so it should work well, so long as the splitter cylinder can be had cheaply. Super 10 has you flipping the range splitter between each shift, instead of once going between high and low range. They work well when lightly loaded, as it's easy to skip every other speed with one. Here is a video if you're not following what I'm saying.

https://www.youtube.com/watch?v=9iHguMIY_9o

Your 466 likely came with a 2 adapted down to 3 to mate with the at545. Super 10s can be had with 2 or 1 housings, depending on the engine it was mated to and the clutch requirements it had. A tape measure will reveal what housing the eaton currently has on it.

According to the IPL, there's only 2 input shafts available, depending if it's a push vs pull clutch. So you'll have to find a clutch and pilot in order to fit that. Not hard, as you'll be ordering that stuff anyways. I feel the hard part would be retrofitting the bus over to having a clutch pedal. The chassis could be had with either manual or auto, but it would be a lot easier stealing parts from a donor truck then purchasing everything needed individually, or fabbing something custom up that will work.

[ster1]

Originally Posted by Booyah45828

Bummer on the tag. It will take some work to figure out what you truly have without it.

Super 10 was a 10 speed but the way the ratios are, you shift it different. They were all OD IIRC, so it should work well, so long as the splitter cylinder can be had cheaply. Super 10 has you flipping the range splitter between each shift, instead of once going between high and low range. They work well when lightly loaded, as it's easy to skip every other speed with one. Here is a video if you're not following what I'm saying.

Your 466 likely came with a 2 adapted down to 3 to mate with the at545. Super 10s can be had with 2 or 1 housings, depending on the engine it was mated to and the clutch requirements it had. A tape measure will reveal what housing the eaton currently has on it.

According to the IPL, there's only 2 input shafts available, depending if it's a push vs pull clutch. So you'll have to find a clutch and pilot in order to fit that. Not hard, as you'll be ordering that stuff anyways. I feel the hard part would be retrofitting the bus over to having a clutch pedal. The chassis could be had with either manual or auto, but it would be a lot easier stealing parts from a donor truck then purchasing everything needed individually, or fabbing something custom up that will work.

Good info! Thanks. I'm going to go back and measure the housing. I found a website that has the dummy guide to SAE bellhousings . Also, Eaton has a fairly extensive guide to find out exactly what trans you have, if you can't find the dataplate, so I'll be going through that as well. It seems the splitter parts can still be found, so that's not a problem. The shifting pattern of this one is definitely a bit odd, but I like that you can shift it like a 5 speed if needed. My only concern at this point is that this trans is supposed to shift at 1200-1400 rpm, and the DT466 doesn't even start to wake up until about 2000 rpm. That has me a bit worried this might not be a good choice.

[Booyah45828]

The trans would be irrelevant to that, to an extent. It doesn't matter what the rpm range of the original motor was. I mean, you can't put this behind a formula 1 engine and take it 20k rpm, but it will do just fine being taken from say an m11 to a dt466.

[ster1]

Originally Posted by Booyah45828

The trans would be irrelevant to that, to an extent. It doesn't matter what the rpm range of the original motor was. I mean, you can't put this behind a formula 1 engine and take it 20k rpm, but it will do just fine being taken from say an m11 to a dt466.

My concern about rpm is, in a situation where I'm loaded or in the mountains, and say run it up to 2500 rpm in 2nd gear. I go to upshift, and I'll drop rpm to match the shaft speed, and that would be about 2000 rpm. The thing won't shift at 2000, I'm told. I'd have to either skip to to 4th, and the engine isn't making any power, or don't be at 2500 unless I'm in 10th and cruising. Am I missing something? Ive never driven a non - synchronized trans before.

[Booyah45828]

Originally Posted by ster1

My concern about rpm is, in a situation where I'm loaded or in the mountains, and say run it up to 2500 rpm in 2nd gear. I go to upshift, and I'll drop rpm to match the shaft speed, and that would be about 2000 rpm. The thing won't shift at 2000, I'm told. I'd have to either skip to to 4th, and the engine isn't making any power, or don't be at 2500 unless I'm in 10th and cruising. Am I missing something? Ive never driven a non - synchronized trans before.

Who's telling you that? The trans doesn't have a brain or anything to prevent you shifting. So long as the speed and gear selected matches the engine rpm, you shouldn't have a problem getting it into gear. Big thing about non-synchronized transmissions is you must match engine/input shaft rpm to gear rpm or it will grind. There is no synchronizer to bring the input shaft rpm faster or slower for it to match speeds and then engage, you have to do it yourself.

So either double clutch, or float gears like the pros.

A little caveat about most unsynchronized transmissions is that the ratio step, or % difference between gears, is usually pretty even in every speed. Meaning that every time you upshift, the rpm you have to match is about the same each gear. So upshifting at 2500 rpm in 2nd, would require you to be around 1600 RPM for it to shift into 3rd. Not a problem, unless you're going up a steep hill and your speed and desired rpm drops too fast for you to hit it to complete the shift.

[ster1]

The manual for the trans talks about not downshifting above 1400 rpm, and "speed vs gear" graphs all show upshifting below 1400, so I am making an assumption there. You're not the only one to call BS on that. Others have said the same thing, so I'll let that go.



I told the guy I'd buy the trans. Even if it doesn't work out for my rig, I can sell it for what I have in it, so I'm going in. The thing weighs 2X what the existing trans weighs, so I'm thinking I have to install a cross member under it. It's also 5.5" longer than the existing. That has meaning for my rig, because my currrent driveshaft has about a 5-6" segment after the output shaft before it has a carrier bearing and another joint before going down to the axle. That extra length may make the articulated shaft unnecessary, and I can use a one - piece shaft. The good thing about that is, that carrier bearing is on a cross member. If I don't need the bearing, I can use the cross member to support the trans. The bad thing is, I'm going to have to install a driveline brake somehow, and using a one piece driveshaft makes that an additional challenge. This is starting to sound like a big ol PITA.

[Booyah45828]

Yeah, the manual does state that about downshifting. That's because the usual use is in larger engines where your governed rpm is 2000 or less. Downshifting above 1400 in one of them would over rev the engine in that case. That usual use is further exemplified by them showing the shifting graph being 1200-1800 rpm. The transmission will be fine operated at 2600.

You're juice brakes? That does make it a PITA as I doubt any HD trans will have provisions for a driveline brake. Air brake would have no need for such a thing. I know certain axles could have been equipped with a pinion brake. It might be easier to source one of them then to source a brake for your transmission.

You could always modify you current brake to fit the transmission, if you have the tools, skills and equipment to do such a thing.

[DrewGerhan]

Originally Posted by cadillackid

might be easier just to gear up the rear// you have 10 speeds so you could go to a bit taller rear end and have plenty of gears and also your top speed at lower RPMs as well.

Hey, I was trying to send you a message, but it said your inbox is full. I'm in the Columbus area too, wanted to pick your brain a little bit. Could you email me drewgerhan@gmail.com

Thanks,
Drew