500/42RE came from 904, 518/46RE and up came from 727. Overall lengths are the same and the OD units are same size. The front of the cases are similar to their 904/727 brethren, so there's some space gained by the 500 toward the motor. All are 0.69 overdrive.

Lou

_________________
Home of Slant6-powered fun machines since 1988

Thanks for all the info. It's a shame Chrysler stopped production out here in the late 70s otherwise I might be able to get my hands on a suitable box as suggested in the replies. Anyone have a A500/518/618 they don't want? I guess I could ship it and some other oparts only available from the states such as electronic ignition.

Thanks to everyone who supplied info.

John

aussiejohn
For help with exporting from the US, and possibly sourcing parts over there contact OzHemii (Jeff) at <jeffmotors@aol.com> He regularly ships either way.
You also probably contact him by posting on moparmarket .com

John

I was also going to sugest Jeff (ozhemi) or MoparMal, both are able to be found on Moparmarket.com forums.

_________________
Richard (aka Fingers)

I have a couple of these adapter kits on hand. /6 to 904 is what they are designed for but they'll also work with a 727 based tranny. The only difference is the shields. I have the 727 flex shield but I never designed a 727 starter shield.

Here is a picture of the adapter installed. I designed it to work with the Denso starter since I figured anyone interested in this setup would be running the modern starter also.

I never really decided to try and market these items which is why this kit isn't listed on the webpage. Send me an email if you're interested.

I sold the last production kit the other day so all I have left is one kit that was my photo model and setup part.

I'm not planning on building anymore of these since it took almost 2 years to sell the last batch. But I do have the CAD files on hand if someone absolutely needs one. However, the cost would be pretty steep to just run out one or two parts.

I am looking into the Laycock de Normanville overdrives as used by Volvo, Jaguar and others in the '70s and 80s. I'd like to use this with a 904 pushbutton.

The Laycock overdrive are adapted to the '46 to '68 Dodge Power wagon as a divorced overdrive, and marketed as a "Denman Overdrive". The PW is a relatively heavy vehicle with low horsepower. There were several Volvo overdrive units, some were built by Gear Vendors. In the Volvo application the O/D shares oil with the transmission, you have to be careful to keep the O/D filled with oil.

A concern is the planetary gears will self-destruct when the overdrive is actuated while in reverse gear. You should hookup a lockout to deselect the relay as in the Volvo application - cutoff the O/D via the backup light switch.

You mount the Laycock on a light crossmember behind the transmission.

http://i14.ebayimg.com/04/i/04/bd/b3/5c_12_sb.JPG

I've owned several Volvos with the Laycock de Normanville overdrive units. They work well and last a long time if they're given reasonable maintenance. I wasn't aware of them being offered as standalone units. You write:
This doesn't make sense to me. Gear Vendors has never been a supplier to Volvo, who always got their overdrive units directly from Laycock de Normanville. Am I misunderstanding you? Maybe you're saying that Gear Vendors is the source of the standalone units?

You're correct that it's vital to have a reverse lockout. This is very easy to accomplish with a normally-closed (NC) relay triggered in parallel with the back-up light switch, and placed in series with the O/D solenoid. Factory installations also have an enable switch that is only closed when the transmission is in top gear. Easy to do with a stick-shift trans; harder with an automatic!

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

"These are some of the reasons Volvo, whose cars have the longest average life expectancy of any automobile company in the world (21 years) bought more than 1 million of these units over the years."

http://www.gearvendors.com/4x4facts.html

The Gear Vendors site may be a little misleading in saying Volvo bought more than 1 million of these units. I think Gear Vendors licensed the
design from GKN, which aquired it from DeNormanville. The site says since 1979 Gear Vendors has been a licensed manufacturer of the GKN units, who sold them to Ford and Volvo, among others. I think Gear Vendors may have only built units for the aftermarket. The GV are much stronger, but fundamentally the same design.

"DeNormanville (maybe the most famous transmission designer ever) created the original product which, GKN (a 6 billion dollar/year public automotive conglomerate) acquired to produce this product for Ford and Volvo. GEAR VENDORS is a licensed manufacturer for GKN and in 1979 started applying racing expertise to the original design."

http://www.gearvendors.com/about.html

There are several '46 - 68 Dodge Powerwagons running the "Denman Overdrive", which I believe is a Laycock design. The Denman kit comes with an adaptor kit which allows them to run "divorced" from the transmission. Otherwise I think it is basically the same as what came with some Volvos.

From what I hear the Volvo units are more than adequate for a slant six.
I figure a 904 slip yoke could be machined to connect to the input shaft of the Volvo O/D unit. There are several Volvo units to choose from, with different torque ratings. The "divorced" O/D would shorten the driveshaft and could lead to U-Joint wear because of the driveshaft angle.

Denman overdrive (908)281-0432

Thanks, Tim, your explanation makes sense. Sounds as if Gear Vendors is maybe playing slightly fast and loose with who-all is included by the words "we" and "us" (that is, Volvo didn't buy from what is now Gear Vendors, but from a predecessor/licensor company).

No matter; the design of the unit is good, and yes, they hold up well behind very torquey and powerful Volvo race engines with only very minor upgrades (which are almost certainly already included in the current-production units...talking here about seal material, etc.)

I'm looking over Gear Vendors' site, and I don't see pricing and dimensional charts for the standalone units. Am I missing them or are they not on the site?

Will you please keep us posted on how your project goes, as far as mounting, total system costs, etc? My '62 Lancer and I are keen to hear how it works out for you.

I was thinking some more about how to set up the overdrive control circuit and remembered that mid-'50s Plymouths were offered with electric overdrive. The 6-cylinder models used Carter BBS carburetors that were fitted with a kickdown switch. This device turned off the overdrive if you shoved your foot down for passing power. It wouldn't be too hard to rig up some kind of a switch just about anywhere on the throttle or kickdown linkage. Another option would be a vacuum switch that would open the OD circuit when manifold absolute pressure increased.

It also occurs to me you could put a vehicle speed sensor inline with the speedo cable (this isn't hard; see Here ) and build a simple logic circuit that completes the O/D solenoid control circuit when the vehicle speed is over, say, 50 mph. I couldn't design such a circuit, but I've no doubt there are others on this board who could do it in their sleep. This, together with a kickdown switch and of course the reverse lockout relay, would give you a nice factory-style control of the OD: Leave the OD switch "ON" and it will engage automatically at 50mph (on the way up) and disengage automatically at 50mph (on the way down). Kick the accelerator for passing, and the kickdown switch would disengage the OD for the duration of your passing maneuver, dropping you back into OD once you take your foot out of it (or manifold absolute pressure drops).

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

The old electric controled OD from the late '40-'60 Were made by Borg-Warner, if I remember corectly. When you wated the upshift into OD, it was necessary to release the throttle, to take the load off the gears, and allow the shift. The "kickdown" switch on the carb, had two separete circuits. One circuit would open the power to the solonid on the OD unit. the other would short out the ign coil, through a set of contacts on the OD solonoid. When the ign shorted out. it would take the load off the OD and allow the solonoid to drop out. This would allow the downshift, and open the ign shorting contacts at the same time, and allow normal ignition. The ign was only shorted for about 1/2 of an engine revolution. This is similar to the push button air shifter on motor cycles.
PS: I have a Saginau 3 speed trans with the BW overdrive, from a 57 chevy, out in the garage.

_________________
Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

When you see an Borg-Warner O/D in a salvage yard you might want to get it, they sell very well on Ebay, I hear these usually don't need a lot of work.
These are especially popular with old Mopars of the forties as the typical gearing of those L-head motored cars does not work well with 70 MPH cruising speeds.

I've now seen both all the following "in the flesh:"

A-500 in an A-body
A-518 in a B-body
727 with Gear Vendors Overdrive in a B-body

I've said it before and I'll say it again: Of all of them, the Gear Vendors Overdrive is by FAR the most elegant. Almost no floor pan mods required (can be done with a ball-peen hammer, whereas the A-500/A-518 require welding). NO crossmember mods required whereas the 500/518 require major reconstruction, especially in an A-body. No transmission mount relocation required, whereas the 500 and 518 need it.

The only downside is that the GVO does need a shorty driveshaft, but that's cheap and easy to have done.

_________________