Hemi Overdrive 4 Speed - Jamie Passon

[JJRJR]

Hey guys,

We're moving forward with the 440 stroker build. The 5 speed overdrive from Passon is still a hear away for my place in line. So, going to go with his Hemi OD 4 speed. 4th gear is a .80:1 so similar to the 5 speed. He says plenty of strength to hold up to a 550 to 600 HP/TQ stroker.

Here's my question. I have a 23 spline A833. He sells a conversion gear set that a shop can use to convert my A833 to the overdrive, the question is do any of you guys know if the kit also includes what is needed to change from the 23 spline to the 18 spline Hemi input shaft? I suspect that I would have to start with the 18 spline Hemi 4 speed then the OD conversion gear set would be easy to do, but not sure about if I have the 23.

Anyone using this transmission from Passon? Thoughts?

Thanks,

John

 

[zupanj]

The 18 spline trans is different from the 23 spline unit beyond the input shaft. Why would you want to change the input shaft in the first place. I have a 23 spline trans in my 'runner with a hemi that puts out well over 500 ft-lbs over most of the rpm range measured at the rear wheels. The trans holds up fine. If you go with slicks it might be an issue but not with street tires. If you really want the OD trans you might be better off buying the trans from Passon and sell your 23 spline transmission.

 

[JJRJR]

Thank you. Really need the OD with 3.91's. Not too much fun on the highway.

 

[zupanj]

You could look into a GearVendors OD unit that installs behind the trans. Also it would be a lot cheaper to change out the 3:91 unless you have it for a reason.

 

[george68hemirr]

gear vendors

 

[Meep-Meep]

I have built two Passon 4 spd OD tranny's and currently have one in my 66 hemi Charger. Both of my tranny's were big bearing cases to begin with so it was a direct swap for me. You can certainly put the OD gear set in a small bearing case but will need the appropriate front bearing retainer. I believe this is available from him as a billet piece for about $125.00. The kit only comes with all the gears and input shaft, a gasket set and a modified 3-4 shift rod. Note: To make the OD tranny transparent to the standard shift H pattern you will need to flip the 3-4 shift plate 180 deg and use the longer rod. This is what the factory did on the aluminum OD tranny's in the 70's and 80's. If you know nothing about your current tranny I advise you plan on 4 synchro rings, small parts kit, tail shaft bushing and seal. There are three types of hub and slider assemblies and two types of synchro rings. Up to 67 uses what I call the bump type dogs; 68 and I believe 69 use the narrow ramp type and 70 up use the wide ramp type. The 70 and up has it's own synchro ring. You will need to know what style your sliders are, or if they are even in good enough shape to reuse, before you order parts.

FYI: The ratios are quite different than the factory. I'm running 3.54 dana and there doesn't seem to be a happy place cruising at 40 MPH. 3rd is too tall and 2nd is too low for comfort. I drove a 4.10 car with the same tranny and it's much better in town. My happy medium might be 3.70s but I really like the 3.54's for freeway driving.