overdrive or high speed gears????

[Joe in Canada]

What is the recommended way to go with 5-1 gear ratio in a friends 1930 V8 Cadillac sedan. Gear vender overdrive or a set of high speed gears. The high speed gears would be 3.6 any pros and cons?

Edited February 4, 2016 by Joe in Canada (see edit history)

[Friartuck]

It depends on your priorities. If the overdrive unit requires invading the torque tube, I presume that is a one way modification when you can't easily go back to original. True, the over drive alternative offers original and higher speed selection. My preference is not to modify a drive train (to that extent).

 

Some history to compare. Lincoln standard ratio was 4.58:1 and they offered a factory high speed gear set for only the lighter bodied roadster at 4.26:1 which represented a 7% higher ratio than standard. The Lincoln Club (group) made a series of high speed ring and pinion sets starting in the 1970's. The first set was a 3.77:1 ratio which represented a 17% increase over original. On flat ground (and down hill) it was acceptable and on slight hills it proved to lug the car. Even a moderate hill required down shifting. The second set (circa 1990's) was at 3.96:1 which was a 13% increase over original.  This ratio set proved well for most roads and hill situations.  If we had to do another set (production run), I would advocate about 4.1:1 which is 10% increase over original. The ratio you've stated of 3.6:1 over the 5.0:1 sounds like a 25+ percent increase over original. If the Lincoln lugged at 17%, surely this 3.6 ratio would lug, also referred to as too tall, meaning to big of a ratio. Investigate how the 3.6 ratio was calculated and query other Cadillac owners who have used it. This 3.6:1 ratio sounds like a disappointment in the making. If this is the first run of gear sets for Cadillac, may I suggest a ratio of between 4.4 and 4.5.

 

My conclusion is the higher ring and pinion set when designed carefully offers the best trade off of performance versus modification. Be tentative of dimensions. A higher speed gear set involves a larger pinion which will force the ring gear to be adjusted (located) possibly requiring modification of the axle housing. PM me for additional comments and pics.

[joe_padavano]

Simply changing the rear gear ratio while keeping the same transmission is a compromise. Changing to a lower numerical ratio will provide high speed cruising at the expense of off-the line acceleration.  While I realize this isn't a drag car, the reality is that changing the ratio will require slipping the clutch more to get moving from a standstill.  Depending on how much you drive the car, this additional clutch wear may or may not be an issue for you.  The heavier the car, the worse this will be.  Adding an additional overdrive gear (which effectively increases the gear ratio spread from first to high) is the better way to go from a driveabilty standpoint, but as noted comes with the penalty of modifications to the car.

[Matt Harwood]

Gear Vendors overdrive. Overdrive totally transformed my '29. Having driven other period cars with high-speed gears, they're pretty soft off the line and it takes a lot of clutch work to get it rolling and hills can be a challenge.

 

Overdrive. No question. Do it.

[JamesBulldogMiller55Buick]

Gear Vendors overdrive. Overdrive totally transformed my '29. Having driven other period cars with high-speed gears, they're pretty soft off the line and it takes a lot of clutch work to get it rolling and hills can be a challenge.

 

Overdrive. No question. Do it.

+1

[padgett]

Have a 2.87 in the garage for my Crossie. Stock 3.25 has it at 6 grand/25 mph in 1st and 2600 at 70 in 6th. Should make a bit more usable. Overdrives are nice, I recall a mod that required drilling a hole in a Saginaw 4 speed to attach a BW overdrive. Popular during the gas crisis. Also a mod for the Laycock in my XK-150s that made it an 8-speed. So have had both.

Easiest is a ring & pinion swap. Suspect the Cad has enough torque to pull a 3.6 (V16 ?) rear with a 3.47 first.

[West Peterson]

Have a 2.87 in the garage for my Crossie. Stock 3.25 has it at 6 grand/25 mph in 1st and 2600 at 70 in 6th. Should make a bit more usable.

Where did you get that? I sure would like to contemplate the same thing on mine.

[Marty Roth]

Our 1930 Packard 7-passenger Touring has a 5.08:1 differential which was great for carrying passengers and luggage through the Alps, and between Paris and Monaco in the 1930s. Operating in "standard" mode, acceleration and mountain climbing is just fine. The 30% Borg-Warner Overdrive reduction means that the engine is only turning 70% as fast at comparable road speeds. This allows cruising at highway speeds with the engine revving at a more reasonable range, and becomes a 3.556:1 final drive ratio.

Edited February 6, 2016 by Marty Roth (see edit history)

[Joe in Canada]

My 30 353 coupe had 4.75 then I replaced them with 3.65. Yes at times I do have to gear down because of the engine lugging. But if I have the speed on hills in my area no problem. We went on the Vintage tour last year in Lancaster Pa. and we hit a few hills there. But with a synchromesh transmission and the dual clutch I cannot say I had any issues because of the low gearing. My biggest complaint of the car is the heard steering when trying to park in tight spots. On the open road the higher speed is great. Can do 55 but comfortable at 45 knowing I have control of the car and able to stop in a reasonable distance. We are planning to do the Glidden tour in NH. this year so we will be back in the hills again. I started this thread for a friend who's car is in the shop having his engine rebuilt after damaging a main trying to keep up on a tour he was on. So he asked me to post this topic for different points of view on the subject. My way of thinking is if I had know about Gear Vender I think I would have gone that rout rather than changing gear ratio. As you can always switch back to your original ratio when encountering long hills with the overdrive. But I have been wrong before. I believe that when you consider what gear ratio suits your car best you have to consider the hill grades in the area you will be driving your car in mainly. When I put these gears in my car I never dreamt I would possibly be driving in the hills / mountains of New Hampshire and Pa. so I may have gone 3.90 if I had known.

Thanks for everyone's input greatly appreciated.

[edinmass]

Having owned more than a dozen early thirties V-8 Cadillac's and driven more than 20,000 miles on them, I shall comment. The eight is rather under powered, and with very poor carburation, this car can be a challenge to get to perform at a more acceptable level for today's driving. 3.6 is too much of a jump. The longest factory ratio was 4.2 if my memory is correct. The 3.6 is fine in the twelve or sixteen with all the torque. More of an issue is the poor steering and stopping ability of a Cadillac built from 1926 to 1931. That being said, a car set up very good can safely travel at 55 to 57 mph. Anything past that is just too much for the chassis. Since either choice will cost about the same, it comes down to a heavily modified car, or one with no obvious changes. CCCA doesn't allow for the over drive unit, so even if you don't plan on points judging it may be a resale issue. I prefer my cars 100 percent stock, but a gear change is a reasonable modification. Remember, the over drive has to handle the torque going through the torque tube, so one must be sure it is installed correctly. Basically, the car is right on the edge of being able to be driven on modern roads at modern speeds. Tire failure is also a big issue. Be sure to run only new tires, less than five years old. I suffered a failure at 55 mph, the tire ripped off the fender and running board and threw it up on the hood and roof. If the passenger had their arm out the window, well.........you get the idea. Drive the car for the conditions and you should be safe. I will have two Pierce Arrows on the tour in New Hampshire, when we meet up with the two tours.(CCCA & AACA)

[Hudsy Wudsy]

Gentlemen, I don't have a thought to share here, but, rather, a question. With rear end gear modifications like you are talking about, do any of you ever worry about axle twist, or is not an issue as long as you're gentle with the acceleration? I'm sure some of these old engines are capable of real torque.

[CarlLaFong]

If the axles don't twist with a 5:1 rear, they certainly won't with 3.6:1

[Joe in Canada]

Another question a friend brought up. Would you switch gears from 5:1 to 4.75 and then put in an overdrive. In 1930 the stock gear was 5:1 then half way through the year they switched to 4.75 I read. Then what would the final ration be if that was done with a gear vender?

[petri]

I drive a 1932 Packard 900 Light Eight on car tours. I find it's very comfortable to "cruise" along at 40-45 mph.It has a 4.36:1 rear end. They offered 4.07 and 4.69 in this car as well. At 50 it's starting to feel a little fast, it will go 60 and I even had it up to 75 mph once, but at that speed it was definitely scary. The chassis just isn't built for it and the steering says "slow down" before it's too late. The mechanical brakes aren't made for higher speeds either. If I'm going on car a tour, usually VMCCA, that has high mile driving days of more than 150 miles, I take a newer old car. With all the stops we make it's hard to get around the course and get back in a reasonable time with a 45 mph car. I wouldn't change gears for anything other than what was available stock at the time. I have a 1932 car because I want a 1932 driving experience. It just doesn't make sense to me to change that objective. Watching the world go by at 45 mph suits me just fine. 

 

Howard Petri

[60FlatTop]

An adaptation that works really well and is reversible is the 1980's Ford 5 speed truck overdrive transmission. If you want a tour car it is a great swap and calms things down in the engine compartment. The shift lever can even be made to look right.

It's worth looking into.

Bernie

[Matt Harwood]

Another question a friend brought up. Would you switch gears from 5:1 to 4.75 and then put in an overdrive. In 1930 the stock gear was 5:1 then half way through the year they switched to 4.75 I read. Then what would the final ration be if that was done with a gear vender?

 

If you're going with an overdrive, I wouldn't worry about any gear swap, especially one that's only .25 taller. It will make no notable difference in the final result. I believe the Gear Vendors overdrive is .78, so your final drive ratio will be 22% less than it is now, or about 3.9 (with the 4.75 gears, it would be 3.705, pretty negligible change). Also bear in mind that the tires are tall, which also effectively reduces gear ratio and affects the engine's ability to move the car. I think a 3.6 ratio, combined with the tall tires, would make the car feel lethargic in all circumstances except at 45+ MPH and as a result, I remain convinced that an overdrive is the way to go. The Borg-Warner unit in my '29 is a .70 ratio, so it's a little steeper and the car cruises happily at 55 MPH, which is where I feel safe. Calculations show 2000 RPM at 60 MPH with my 7.00-20 tires and the 30% overdrive, so I'm very happy with about 1900 RPM at 55. I'm also happy that I can put it in high gear with the overdrive off and let it idle silently at a walking pace, as intended. It'll still pull cleanly from 3 MPH in high gear. I can't imagine it being any slower than it is and lower gears would totally kill it around town.

 

I personally wish I had used a Gear Vendors in the first place. You trade a little overdrive ratio for bulletproof reliability. My B-W overdrive has been spotty at best and I'm doing a modification now to improve that and get rid of the electronics, but a Gear Vendors unit would have eliminated all issues now and in the future. It's worth the investment.

 

Leave the rear gears alone and get the overdrive. No contest in terms of usability. 80% of the time the car will feel like it does now, but when you're cruising at more than 40 MPH, overdrive will make it feel a lot more relaxed. Your bearings will also thank you.

Edited February 9, 2016 by Matt Harwood (see edit history)

[Joe in Canada]

I fully agree Gear Fender is the best option to go to for the best of both worlds. But another thought is the final ratio in the transmission.  Did the factory have different ratios in the transmissions that could make a difference from car to car same model. Example like they did half way through the year with the crown & pinion gear ratio in 1930 Cadillac? Or am I thinking to far out of the box now.

[Matt Harwood]

Top gear in almost every car made before the advent of factory overdrive transmissions is 1:1, direct drive. First and second gears varied by make, model, and application, but top gear was almost always 1:1. There's not much to be changed (or gained) by altering the transmission's ratios. Yes, I suppose you could find some slightly different first and second gears to make it feel a bit peppier around town with the tall 3.6 rear gears, but it'll never be enough to compensate and bring back the performance of the original 5.00 gearset.

 

You're definitely over-thinking it. Think of it like this: you can either re-engineer both the transmission and the rear end, spend months or years looking for ancient parts that may or may not exist and may or may not be usable, find someone to competently remove, replace, rebuild, and reinstall both the rear end and the transmission, figure out how to pay for all this, and end up hoping that the result delivers a good compromise between around-town punch and high-speed comfort (which it won't).

 

Or you can put in an overdrive.

 

I promise, once the overdrive is in the car, you'll wonder how you ever got by without it. Despite the headaches, I like the one in my '29 so much that I'm considering installing one in my '41 Century while I have it apart, and that car already has 3.90 gears in it. Hell, if I keep this '41 Buick Limited limousine I bought a few months ago, I may even stick one in there. I'm a believer.

[C Carl]

Hi , Joe ,

Looks like you have your answer drawn from years, and tens of thousands of miles of experience. Let me see if I can offer what may be an interesting perspective. Chronologically I am 71 years old (my doctors tell me I am physically about as old as your '30 Cadillac). We all know guys or gals in their 70s who buy new Cadillacs. Now consider the septuagenarian who bought a new Cad in 1930, or 1927 as in the case of my old sedan. Born before the Civil War. Could not have even seen a car until in their 40s. Lived over 1/2 their lives in horse-drawn days. Might have harnessed up a brace of stout steeds to a 4 place high-wheeled carriage. Now how far could that pair of ponys pull said conveyance loaded to max capacity over level roads in a day ? Not a horseman myself, I have been told 20-25 miles or so. Any expertise on this to verify ? Now, a new Cadillac imposes equestrian obsolescence. Every hour the Cad carries its occupants half again as far as the nags could drag 'em for the entire diurnal duration. Introduce grade, up or down, and the difference in capabilities is magnified.

Uh , oh. I just got a call and have to run. This is all to suggest enjoying these old cars (neither Pierce-Arrow , Duesenberg , European exotic or other faster car), as they would have been driven by the satisfied original owner. There is certainly every reason to spare engine stress at modest cruise speed with O.D. But handling limitations in an emergency situation requires restraint in the velocity department.

I just got back from pre-running my intended route , Portland , 'Frisco , L.A , 'Vegas for CLC G.N. mid April. Will you be there ? This is intended to be my last significant road adventure. Will the '27 and its ailing driver make it ? You see the humble 4 door in the background behind the '31 Packard. Next , the pinstriping has been repaired on this original unrestored relic. Next one of the hotels/motels I found with mandatory covered parking available , each 1/2 days drive apart. This , on the elegant end of the spectrum , was built in 1926. Appropriate photographic opportunity ? Nice view spot used to alleviate a hydraulic imperative. Finally , my new wheels turned out nicely. This will preserve the originals in great shape for the next owner. The paint on them is just getting a bit delicate. Tom Dessert near Vancouver , Wash respoked the spare wheels I got with the car. He can be contacted at dessertt@hotmail.com , yes , two "t's".

TBC , CC

[jrbartlett]

I can tell you my experience with a '29 Packard Super 8 roadster with 106 horsepower, 700x20 tires and a 4.07 to 1 rear end. It's a workable compromise for the flatlands of Texas at 50 MPH and the steep hills in Colorado and the Northeast, which I've experienced with the car while on Glidden Tours in recent years. By compromise, I mean it's geared too low for the flatlands, and too high for the mountains. Not perfect in either case, but usable. If I went to perhaps a 3.5 to 1 ratio, it would be great on the flats and terrible on hills and takeoffs (not enough horsepower). I'd love to have a Gear-Vendors unit for both situations. 

 

In contrast, I also have a '35 Auburn super-charged convertible sedan with 150 horsepower, the factory Columbia two-speed rear axle and 700x16 tires. Low range is 4.55 to 1, so it's peppy around town but gets up to high RPMs too quickly. High range has roughly a 3.3 to 1 final ratio, so it's good on the road for cruising at highway speeds -- 70 MPH is about 2,400 rpm (my rod bearings are inserts now). It's great to be able to just flick the switch to go from one to the other.  

 

And in total unfair contrast is of course the Duesenberg, with 265 horsepower, 700x19 tires and 3.54 to 1 rear end. It pulls everything just fine and cruises easily -- about like a modern car. But who wants to drive one of those around in modern traffic.

[Joe in Canada]

Thanks I really appreciate all the different angles on the subject. I will learn more from people with experience than ten years of trial and error. At my age I may not have ten years of trial and error come to think of it. I must also say I have been to Texas many times and yes it is flat  compared to the north east and especially Colorado another beautiful state.

  This years Glidden will give most old cars a good workout I think as they have several long hills on the route. More than likely longer than the ones in Lancaster Pa. last year.

[scott12180]

Matt Harwood recommends an overdrive based on his experience.

Matt, you have one in a Cadillac?  And doesn't Cadillac have a torque tube?

If a car has a torque tube like a Cadillac or Lincoln,  how would the overdrive be installed?  I assume the torque tube would be removed and a section cut out, then the overdrive installed.  Is that so?

 

I'm aware of Gear Vendors and have used a Mitchell on a Packard.  Could you send your whole torque tube to either of these people and expect that they would install the overdrive for you?  Then it seems that you could just reinstall the new OD Torque Tube.

[Matt Harwood]

I did send my torque tube to Lloyd Young for installation. For Gear Vendors, they send you the parts, you need to find a shop to install it. Looking at how mine was built, it doesn't look like a terribly difficult job, just be sure to measure twice, cut once, because you only get one crack at making the driveshaft inside the correct length. The installation on my car is actually rather clean and most folks won't see it as anything out of the ordinary by looking underneath. One of our other members just installed a Gear Vendors overdrive in his 1930/31 Cadillac's torque tube and is quite pleased with it. There's a thread about it here somewhere.

 

I had photos of it here, but it looks like I lost them in the last forum update. I'll see if I can find some to post. But yes, you do need to cut the torque tube for installation.