Does anybody have an overdrive unit as an add on installed and working? I have seen some advertised in Classic Cars Mag. and wondered what are the ramifications of such a change, does it work as it should, what modifications has to be made, what is the success of them on our Durants. I would like to be able to cruise at highway speeds (about 50 mph.) without the drive train sounding like it is stuck in second gear. I know this changes the originality of the car, but would make driving more enjoyable. Jim

Do You own a car built by Durant? Yes

Maybe you can ask Lance Haynes about his 5 speed chevy S-10 conversion. That might be the way to go.

Do You own a car built by Durant? 1929 MODEL 70 COUPE & 1930 6-14 SEDAN

The Mitchel overdrive of Model A fame has worked well for member Tony Burke. He installed their open driveline model in his 1929 Model 60 Coupe with good results.

Hi Jim and Gary.
Yes we slipped a totally stock used 1995 Chevy S-10 pickup
(V6 only) 5 speed all synchromesh with over drive floor top loader transmission in an all stock 30 Durant rumble seat deluxe coupe.
Course we went threw the engine and boosted the horse power and now drive 60 MPH with no problem. We welded a stock cut off chrome 29 Model “A” ford shift lever on a cut off shifter lever on the B&M replacement shifter kit to shorten the throw and keep everything in side the cabin all looking very stock. Custom made a protruding new crankshaft pilot bronze pilot bearing as the input shaft is a little short. (Note the S-10 has the longest input shaft of all modern 5 speed overdrive transmissions) We drilled and tapped the stock Durant bell housing and used the stock 9” Chevy clutch disc (same size as the Durant) and made a bushing for inside the stock Durant throw out bearing carrier and built a custom Chevy drive line of course to hook up to the stock Durant rear end.
We also had to remove the main brake cross shaft and alder the center part to clear the S-10 transmission. Kenyon Machine Shop did all the precision work. Presto modern 5 speed and no grinding and 60+ Mph on the freeways.
Later Lance

Where Are You From? www.lancedurant.com

Do You own a car built by Durant? a whole bunch of them.

Some of the Durants came with a 4 speed gearbox. I don't know what the ratios are, but top gear is one to one, so to improve things you need a numerically lower rear end. If you own a gear factory, this is relatively straightforward. You could also try to install a Ford top loader overdrive transmission. These were used in about 1978-80 for pickup trucks. Some come up on E-bay. In fact I'm trying to get one but they always seem to go a little higher than I expect. There was also an aluminum housing 4 speed used with 1980's Mavericks and Mustangs. Don't have the reputation the iron top loaders have. Then there's the Volvo overdrive.
If I were you, I'd be more worried about stopping than getting up to highway speed. Most of the time these cars ran on gravel roads at about 40 mph tops.

Do You own a car built by Durant? Yes

I looked into adding an overdrive to my car when the time comes, not to go faster, but to lower the engine RPMs. The Volvo Laycock type J is a good choice, but it's very popular right now and prices have gone up. Keep in mind that going faster means keeping your brakes to tip top shape.

I appreciate all the input so far, lots of good ideas. you are right Rick about brakes and stopping. I have redone all the brakes and they work well now. Not as good as modern hydraulics, but acceptable. I agree about wanting to reduce engine rpm's, this is really more important than going fast. I don't exactly want speed, I just don't like to feel I'm about to get run over by others on a 55mph speed road.

Do You own a car built by Durant? Yes

Jim, Lance and others,
I have been searching for some time to lower the revs on my D66 which has at some time in its life had a 4.4 ratio replacing the specified 3.9 ratio differential. To fit up an overdrive appears to be somewhat difficult, maybe the "A" Ford or other units mentioned in this discussion could be worth investigating. I have also found a Differential specialist who has grafted Land Rover Centre into a 1933 Chrysler diff and I am going to take a spare diff housing and axle setup for him to investigate doing likewise with. David Cornell doesnot think it will be possible with our type of Diffs so it may come down to having a new crown wheel & pinion made by specialist gear makers. There is one in Melbourne and possibly one other in Brisbane in Australia. There is also one other in USA that Mac Irvine quoted at US$1500 to manufacture a set which on current exchange rates would be competive with the ball park Au$2000 per set given to me here. Maybe if there is enough interest we may be able to get a more competive price if a number of centres were to be made. May have to blog another forum question to gauge the demand.
Lance you might be able to comment on my situation with the 4 speed D66. I would like to look at the 3.5 ratio giving the 4th gear as an overdrive with the 3rd gear being closer to the original 1to1 top gear. Would this place undue strain on the 1st gear starting off on hills and would the sedan be struggling to maintain say 50mph on the open road, ie use more fuel with the higher ratio etc.
Also does any one have the figures for the advance curve and spring tension for the Distributor on a 15L engine? My current engine failure has been caused by pre-ignition and we suspect the springs are not returning the distibutor to normal after accelerating or coming under load.

Do You own a car built by Durant? 1929 D-66

Hi Phil.
Your questions are not easy to answer as we are all different of course and I have the luxury of a very good friend of mine (Greg King) owning his own large machine shop (Kenyon machine Shop) close to me that takes a interest in helping me on our rare historic cars.
First of all most distributors that have the dual spring counter weights have one spring set stronger than the other to give a wider range of advancement as the RPM’s increase. I can tell you from experience the loose one should be almost falling off the posts and the other one snug. Also everything should be very clean and then oil with a light weight sewing machine oil like 3in1. Also after getting my 1929 Durant stock 6-66 running and driving it with this stock 4 speed I realized there was not near enough power (48 HP new) or any overdrive built into the stock transmission to drive this car around San Diego like I wanted to. Course most people know I swapped everything out very methodically now running a stock junk yard $350.00 Ford Fairlaine inline Ford engine and stock C4 automatic with a 29 Model “A” shifter and tranny top and floated my clutch petal back in for looks. I have good original wood wheels that is why I have to run the stock Durant rear end. We did mate up a stock Chevy C4 (Ford top loader no workie as the input shaft is too short to reach the crank shaft) 5 speed top loader w/over drive to a 30 Durant coupe. Now a friend drove my 29 once and twisted one of my axles into. I have been driving this car for over 5 years up in the Bay Area on Tour with Bert Babic and LA and all over this county no problem. I take off slow.
Now if a guy changes the ring and pinion ratio you will not have enough power. You can regrind the cam to higher lift and more duration and install 3 ring (less drag than stock 4 ring) new light weight pistons (Egee in LA is completive now so get a price) and mill the head a bunch, and ream all the ports in the block and manifold and install a bigger carb and bigger exhaust pipe. Be sure and X-ray all the rods and peen them. They are weak and a little undersized. Everyone should drive Rick’s roadster that we did all this to. Big difference.
BTW you cannot get overdrive out of the Durant stock 4 speed because of the way it was built.

Faithfully. Lance Haynes

Where Are You From? www.lancedurant.com

Do You own a car built by Durant? a whole bunch of them.

Hello again.
The answer to braking on all deluxe wire wheel Durant cars is to have the after market Model “A” control bands(heated red hot) and installed over the outside of each brake drum and two will fit. They have to be cut and rewelded together as our Bendix brake drums are 11” on the outside and Ford is 11” inside the drum. Must turn the drum cause when they cool they distort the drum. Also use the Nascar high temp type brake lining and you can stop as well as any car on the road. Ask Rick. We did it to his Roadster and a number of 30 Durant cars. Wood wheel cars turn the drum, install high temp lining and keep adjusted properly.
Faithfully. Lance

Where Are You From? www.lancedurant.com

Do You own a car built by Durant? a whole bunch of them.

No one has mentioned the two speed rear end option. It was popular in Fords, and a few other makes used them.

Do You own a car built by Durant? yes