4.88 Gears

[bob duffer]

I have been noticing my engine has been racing ( high RPM ) at 35- 40 miles and hour , it seems like it wants to be shifted again into a 4th gear but there 

are only 3 gears. Then i look through my shop manual and notice the rear end has 4.88 gear set . Has any one changed there gear sets with good outcome?

Or would  trans or clutch problems do the same thing . I feel the car should go at least 45 MPH with out the high RPM. I can't believe they put 4.88 gear set in a car like 

this .

[nzcarnerd]

Maybe you should invest in a tachometer to see just what revs your engine is pulling.  Tachs are readily available, not expensive and easily fitted.  By my rough calculation your car should do 3280rpm at 60 mph (assuming you have 7.00 x 16 tyres) so at 45 it is doing just under 2500 rpm and is going to sound busy because there is a lot happening up front and there is not much sound proofing.  These old cars are geared much, much lower than modern cars with overdrives.  Back in the day about 40 mph was as fast as most people drove and the ability to climb hills in top gear was more important than a high cruising speed.  Your engine develops peak power at 3200 rpm so 60 mph is about as fast as you can reasonably expect it to go.

 

In that era there were plenty of cars with rear end gear ratios in the high 4s and low 5s.

 

Looking in my copy of The Standard Catalog I see that the earlier Series 60 cars (1931 to 1933) use taller rear gears but I have no idea whether they are interchangeable with the 1934 car.

 

There have been plenty of people wanting to raise the cruising speed of old cars and the arguments for and against will continue for a long time.  Some will argue that it is best just to drive the car within its own limits.  I understand that is not easy in modern traffic situations.  Driving a car at 45 mph on a modern two lane road (not a freeway) does rely to some extent on the patience of other road users.  Here in NZ we are fortunate that some main highways have passing lanes that allow faster traffic to get by every few miles. In a couple weeks my two sons (age 16 and 18) will be driving our 1928 Studebaker GE Dictator and 1929 Plymouth to an event which involves driving nearly 100 miles on the main highway before turning off on to less trafficked roads.  The Plymouth will cruise at 50 but both will find that 45 mph is as fast as they can maintain.  The Studebaker has 4.66 rear gears and due to the larger (5.25 x 20) tyres runs at similar revs to the Series 50 Buick and certainly sounds busy at speed.  The 1934 Series 40 Buick I had many years ago would cruise at 55 mph but I know it was working hard at that speed, even with its 4.33 gears.

 

Overdrives of various types have been made available but it is not easy to do with a torque tube drive system, although I know that there is a set up available here in NZ for the Ford Model A.

[1939_Buick]

You may have a slpping clutch. Should go faster than 45 mph

 

If you look at the links at the bottom in post 5 in link below you see other info on rear end ratio changes

Part of your problem is spiral gear set vs the later hypoid design (from 1937?)

'39 Buick Team

Edited May 17, 2015 by 1939_Buick (see edit history)

[Matt Harwood]

Bob, I'm sure it sounds busier than it is, and I agree with everythign NZcarnerd says. If you do the math, Assuming a 30-inch tall tire (I'm just guessing), it's turning 3279 RPM at 60 MPH. While that's higher than you should run for any extended period of time, 45 MPH is a more reasonable 2460 RPM. We're so used to our overdrives that we think that a car should be turning 1500 RPM and the mechanical valvetrain and reduced sound insulation around the engine makes it sound like it's screaming when it's not. I used to work for a dynanometer manufacturer and when putting a car on the dyno, you'd think a rod was about to come through the block at 3000 RPM just based on the sound. So yes, it sounds busy but it's not and you're not hurting it by spinning it at those speeds.

 

I have an overdrive on my '29 Cadillac which I really like using, giving me about 2000 RPM at 55 MPH, but when I don't use it, the engine is just as happy buzzing along at, say, 48 MPH and higher RPM. Actually, I've noticed that it actually seems happier without the overdrive. It stays cooler under most circumstances, which is counter-intuitive. So I wouldn't sweat 45-50 MPH in your car, It's not spinning nearly as fast as it sounds.

[AzBob]

Bob, I had my 1926-26 out for a spin yesterday. It has a 4.9 : 1 axle ratio with 32" tires. Believe me, at 35 mph it seems like it is racing. As the others have stated, there is no sound insulation and little vibration damping. You would think you are going nearly twice that speed. One of the idiosyncrasies of driving cars of this era. 

[Marty Roth]

Lloyd Young can modify your torque tube to adapt a vintage Borg-Warner 30% overdrive. This gives you the equivalent of a 3.416:1 differential ratio for cruising, but you can still kick out of overdrive for hill-climbing when needed.

 

When in overdrive, you are doing 60 mph, but your engine thinks it is doing 42 mph.

 

The '34 Buick is a comfortable cruiser, factory equipped with vacuum-assisted power brakes, and when properly adjusted, they are more than capable of safely stopping your car from highway speeds.

[hidden_hunter]

Lloyd Young can modify your torque tube to adapt a vintage Borg-Warner 30% overdrive. This gives you the equivalent of a 3.416:1 differential ratio for cruising, but you can still kick out of overdrive for hill-climbing when needed.

 

When in overdrive, you are doing 60 mph, but your engine thinks it is doing 42 mph.

 

The '34 Buick is a comfortable cruiser, factory equipped with vacuum-assisted power brakes, and when properly adjusted, they are more than capable of safely stopping your car from highway speeds.

 

As opposed the the 26, where the manual tells you not use the brakes unless it's an emergency

[bob duffer]

Thank you all for the info .. Im going to get a cheap tach and see what the engine is doing .

[Guest Barneys_Bud]

If you get a repo copy of the service manual they should (mine for the 41 does) have a gear ratio chart that shows the different gear sets and the engine RPM at different speeds.

 

You need to remember that when these cars were built the highest speed limit you would encounter was 45 mph.  This would be on a good day with an exceptional road.  So when they built the cars they made them  to curse with at around 45 mph.  In fact if you look at some of the older speedometers they are labeled red at that point.  4:10 and higher (numerically) were very common in older Buicks.  Mine came with a 4:10 and yes they do wind up when you try to do todays highway speeds.  Making this  even more challenging is the fact that Buick had their own gears made and they are not shared with any other GM cars.  To further complicate things Buick in their infinite wisdom chose to rivet the ring gears in place which makes them even more difficult to deal with.

 

Cheer up, all is not lost!  I had a fellow who is a good rear end guy remove the rivets and bolt a new gear set into mine.  He guaranteed it and I have gone many miles with out any problem.  The center sections are interchangeable in Buick's up till about 52 I am told.  The later ones have lower (numerically) ratios because they were installed behind automatic transmissions.  I put a 3:90 In mine and it seems comfortable at a little over 50 mph.  I wish I could have found something closer to 3:7 since that would have been ideal.  

 

I hope this helps.

 

Have a great day !

[LAS VEGAS DAVE]

Do you have a contact info for the guy that did yours?

[LAS VEGAS DAVE]

Lloyd Young can modify your torque tube to adapt a vintage Borg-Warner 30% overdrive. This gives you the equivalent of a 3.416:1 differential ratio for cruising, but you can still kick out of overdrive for hill-climbing when needed.

 

When in overdrive, you are doing 60 mph, but your engine thinks it is doing 42 mph.

 

The '34 Buick is a comfortable cruiser, factory equipped with vacuum-assisted power brakes, and when properly adjusted, they are more than capable of safely stopping your car from highway speeds.

 

 

Do you have the contact info for Loyd Young?

[Daves1940Buick56S]

  So when they built the cars they made them  to curse with at around 45 mph.

 

Yes, I *do* start cursing at 45 mph!!! 

[Marty Roth]

I see you already have Lloyd's contact information.

 

I drove my '34 yesterday, and am still smiling.

[LAS VEGAS DAVE]

The Loyd Young overdrive has now been in our car for several months and over 1000 miles. We use our car almost every day and the combination of the overdrive when needed and the stock gearing for around town make it a great drivable antique car.