I have searched the postings to find out if this question has been brought up earlier, but not found anything.

Does anyone know if the tailhousing containing the tailshaft overdrive unit in the A500 family transmissions will fit the main case of the 904 in my '77 Aspen, eventually with modifications within reason? I don't know how shifting into overdrive is done in the A500, if it is made internally or if there is some kind of external mechanism? I also know that lubrication of the overdrive unit is an issue that must be dealt with.

If not an easy switch, does anyone know if the 904 main case can be filled with the necessary A500 components to make the conversion feasible?

I also have a 727 from a slantsix van, the same questions applies to the A518/618 transmissions versus the 727. Anyone with knowledge about those?

I can easily do smaller modifications, so what really want to know, is this possible at all? Has anyone tried?

_________________
Aspenized

The queation has been discussed, but not recently that I'm aware of. As I recall, the gist of it is that there are addition oil circuits in the overdrive transmission and additional passages that pass through from the front case to the tailhousing, Those passages are not machined into the A904 case so it would not be possible to simply transfer the guts from an A500 to an A904.

The A500 can be made to fit into an A-body car but it requires extensive modiciation to the floor, hump, and crossmembers. It can be done, but it's not for the faint of heart.

_________________
David Kight
'62 Valiant Signet, White
'98 Dodge Dakota
'06 Jeep Liberty

Growing older is unavoidable but growing up is strictly optional.

Thank you for answering. I know that oiling is a problem, I have seen info about the A500 that says that the oiling to the overdrive unit with the stock A500 oil pump is a weak point in itself, and for racing they should fit a heavy duty pump and clean up the oil channels. If channels cannot be bored through the 904 casing, perhaps they can be led to the outside and continued as an external pipe to the tailhousing?

Has anyone out there fitted an A500 with adapter plate to a slantsix in an F-body? Crossmembers are not the same problem as on the A-body because of the different layout of the torque shafts; they are running forward and with a 90 degree bend they are mounted in front of the K-member on the F-body, so the crossmember holding the rear transmission mount is just another bolt-on bracket. I also think there is more room in the tunnel around the tailhousing on the F-body as well, but I haven't had the possibility to compare measurements with an A-body.

_________________
Aspenized

In addition to the hyd. problems Dakight pointed out,the rear bulkhead in the main case is different.It has a larger overunning clutch with a larger, different bolt pattern that the OD guts bolt to.

_________________
V8?? We don't need no stink'n V8!!

Ceej has from time to time mentioned somebody making an adaptor setup to use a Volvo-spec Laycock overdrive behind a Torqueflite. The Volvo O/D units are durable and work well, and are readily rebuildable. This is the same basic unit used by GearVendors (which is why they are very picky and demanding about selling subcomponents…everything they make has a serial number, and if you don't give them a valid s/n, they won't sell you parts; this is to prevent cost reduction by using Volvo components).

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

Must research Volvo overdrives. I would be very interested in adapter plates for 904s and even a Ford C-6.

The easiest way to mate an A-500 to a slant is use the adapter from an A100. Failing that take the A-904RG and the A-500, cut both bellhousings off near the pump and weld the slant six bell to the A500 transmission.

_________________
Joshua

I'll look into the Volvo unit myself, it is a LOT easier and cheaper to find over here than a A500, and the gear vendors price is a bit steep...

Dan, do you know if the Volvo/Laycock overdrive unit came in different configurations, or is it the same unit for all Volvos?

I'll take a look in norwegian and swedish Volvo forums, if you don't already know, we're neighbors and our lingos are nearly the same. I will gather and translate any relevant info that I find and make a summary available here.

_________________
Aspenized

I just found this link to a remote mounted unit; seems they made a front plate with entry for a driveshaft in it, can be placed anywhere under the car. Maximum Overdrive No prices though.

_________________
Aspenized

YEAH!!!! That's what I'm talking about!