Jantrix Posted December 30, 2014 Share Posted December 30, 2014 (edited) My current Allison powered project is progressing nicely and I'm working on the "cockpit". Does anyone know what sort of tranny is on the AMT Allison V12? Maybe some of the truck guys recognize it. What sort of shifter/clutch pedal/throttle combination should I be using here. There is very little reference on the internet. This one pic from Big Al doesn't show much? Is that lever a shifter or a throttle? I'm not seeing any pedals. Any help here would be much appreciated. Edited December 30, 2014 by Jantrix Quote Link to comment Share on other sites More sharing options...
Old Buckaroo Posted December 30, 2014 Share Posted December 30, 2014 I am not familiar with your 1/1 subject. But from being around all sorts of equipment I would guess that lever to be the clutch - like on early dozers and tractors. Quote Link to comment Share on other sites More sharing options...
Old Buckaroo Posted December 30, 2014 Share Posted December 30, 2014 After studying that picture more , I am thinking that is the brake lever. But still there should be something to engage power to the trans with no visible shifter. Quote Link to comment Share on other sites More sharing options...
Ace-Garageguy Posted December 30, 2014 Share Posted December 30, 2014 (edited) The "gearbox" on the AMT Allison is a gear-reduction drive for a prop and accessory drives in an aircraft. A large multi-disc (possibly a "slipper") clutch is all that would really be necessary, as the Allison makes enough torque to shred an in-out box made for a car engine. Google "Allison powered pulling tractor" images, and you'll find lots of shots like this, which shows a plausible design for a clutch housing (yours would be single, of course). A Google image search for "Arfons Allison Green Monster" should also pull up some good photos, as several versions were built specifically for drag racing exhibitions. Here's one oddball Allison drivetrain. The lesson is...make up something that looks kinda like a clutch housing and / or a BIG transmission. Nobody is really going to be able to tell you it just won't work. Another option is a BIG auto trans from an OTR truck, etc. A big automatic gearbox could conceivably be beefed up for drag racing behind an Allison. Edited December 30, 2014 by Ace-Garageguy Quote Link to comment Share on other sites More sharing options...
Jantrix Posted December 30, 2014 Author Share Posted December 30, 2014 The "gearbox" on the AMT Allison is a gear-reduction drive for a prop and accessory drives in an aircraft. So you are saying that this current gearbox is in no way correct for this application. So without rebuilding a tranny from scratch what would be your recommendation for a shifter/clutch pedal/throttle combination? I realize I may have to throw mechanical correctness out the window and go with "hey that looks cool." Quote Link to comment Share on other sites More sharing options...
Ace-Garageguy Posted December 30, 2014 Share Posted December 30, 2014 (edited) Have you got a normal funny car bellhousing in your parts stash mayhaps? Look at post #4 again. All you really need is a big bellhousing and some kind of output-shaft-looking thingy. Edited December 30, 2014 by Ace-Garageguy Quote Link to comment Share on other sites More sharing options...
dodgefever Posted December 30, 2014 Share Posted December 30, 2014 There was a feature on Big Al in an early '90s R&C. From memory, it had a homemade multi disc clutch and direct drive through a large diameter (~12 inches) torque tube into a flipped Pontiac rearend. The rear axle was mounted upside down to work with the reverse rotation of the Allison vs. an auto engine. Quote Link to comment Share on other sites More sharing options...
Ace-Garageguy Posted December 30, 2014 Share Posted December 30, 2014 This is from a n article in Hemmings Daily http://blog.hemmings.com/index.php/2012/01/18/rip-jim-lytle-a-power-crazed-genius/ about the original Big Al: " In his first run, the clutch incinerated before he was halfway down the strip. Lytle was undeterred and crafted his own replacement, now believed to be the first multi-disc clutch ever made specifically for drag application." Quote Link to comment Share on other sites More sharing options...
Ace-Garageguy Posted December 30, 2014 Share Posted December 30, 2014 (edited) Multi-disc clutches look more or less like this. All you need is a big. deep bellhousing, and a pedal with a hydraulic master cylinder, with a hydraulic line running into the rearish part of the bellhousing...to be completely believable. You can do a hydraulic clutch pedal a jillion ways. Here's one. Hydraulic clutch release bearings live inside the bellhousing behind the clutch pack, and eliminate any need for linkage to show on a model. One pressure line from the clutch master cylinder is sufficient to be technically correct. The second line is for an external bleed, which is not entirely necessary, though it would be helpful on a real car. Edited December 31, 2014 by Ace-Garageguy Quote Link to comment Share on other sites More sharing options...
Jantrix Posted December 31, 2014 Author Share Posted December 31, 2014 Thanks very much. I'll dive into my parts bin. Much appreciated. Ace you are always there for tech talk. Quote Link to comment Share on other sites More sharing options...
Jantrix Posted January 1, 2015 Author Share Posted January 1, 2015 Bill, This is from a Merlin powered '55 Chevy from Youtube. But I think your idea is the same yes? Quote Link to comment Share on other sites More sharing options...
Ace-Garageguy Posted January 1, 2015 Share Posted January 1, 2015 (edited) Bill, This is from a Merlin powered '55 Chevy from Youtube. But I think your idea is the same yes? Basically the same idea, yes, but with some important differences. Here's a side shot of the '55 Chevy setup. Between your photo of the drive unit before it was painted and the one above, I have a pretty good idea of what's going on here. In your photo, you can see a large plate bolted to the end of the engine to support the drive. Then comes a roughly egg-shaped transfer case to get the drive output shaft lower in the car (to compensate for the engine being mounted very high, probably to clear the front suspension and crossmember in the '55 chassis) and also, possibly, to change the speed of the output and to reverse its rotation. Then there is a cylindrical housing, most probably for a conventional multi-disc clutch, to which is bolted a conventional automotive gearbox. All pretty straightforward, and some ideas could be used on your Allison-powered model...or not. Depending on whose story of the original Big Al you read, some references are made to Lytle using a somewhat unusual war-surplus reverse-rotation Allison in order to be able to use an automobile rear end made for the conventional automobile-engine rotational direction, and avoid a rotation-reversing transfer case as it appears the '55 Chevy uses. One of the Allisons in the P-38 was reverse-rotation to counter prop-torque effects, so that was possibly the source. It's also relatively straightforward (but somewhat involved too, if that makes sense) to convert an engine to rotate backwards from it's original design, and involves primarily different cams and piston mods or replacements. It's been done quite a lot over the years to adapt engines to odd applications, so your Allison could conceivably be running backwards...just like some descriptions of Big Al would have it. If you say you're running a reverse-rotation engine (either military original surplus or converted), then all you need is a big can (bellhousing) to contain a multi-disc clutch, and your choice as to whether to use a gearbox, like the '55 Chevy does, or not...like the original Big Al. Here's some more info on Allisons, from a reputable source. http://www.aceallisons.com/ Edited January 1, 2015 by Ace-Garageguy Quote Link to comment Share on other sites More sharing options...
Jantrix Posted January 1, 2015 Author Share Posted January 1, 2015 (edited) So I think, if I cut per the pic. Add a plate and then a drag racing style tranny, I can get pretty close. Edited January 1, 2015 by Jantrix Quote Link to comment Share on other sites More sharing options...
Ace-Garageguy Posted January 1, 2015 Share Posted January 1, 2015 Similar to the setup in the '55 Chevy, yes. Quote Link to comment Share on other sites More sharing options...
Jantrix Posted January 1, 2015 Author Share Posted January 1, 2015 Good enough for me. Thanks yet again. Have a great new year. Quote Link to comment Share on other sites More sharing options...
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