Author Topic: Axle Replacement for Different Gear Ratio  (Read 672 times)

Starchild

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Axle Replacement for Different Gear Ratio
« on: April 16, 2024, 06:53:24 »
Would like to hear about other members experience who have changed gear ratio's in the W113 rear axle.

 My Pagoda (280) will be undergoing some mechanical repairs by a well known MB repair shop.  At this time I am thinking about a change out of the axle so the car will operate at  lower RPM's at highway speed.

My question, is there a loss of torque at lower speeds by doing this change? I like the way the automatic transmission feels when taking off at a standing stop at a traffic light. Have had the car for 30 some years so have gotten used to the way the car is currently geared. Not so much a fan of the high RPM's at 70mph after an hour or more. Am sure car would be more pleasant to drive on  a longer trip with a swap.  Don't want to lose the performance and feel in the lower gears. I have not had the pleasure of driving a Pagoda that has an axle swap. So not sure of what to expect.

Would  really like to hear from members who have had the original factory spec axle and later changed it for the advantage of a quieter engine at highway speeds.

Any disadvantages  regarding performance of doing this? I understand there are two possible axle ratios from the sedans. Is one  axle ratio better than the other?

Appreciate hearing any pro's or con's of doing a swap. 



stickandrudderman

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Re: Axle Replacement for Different Gear Ratio
« Reply #1 on: April 16, 2024, 07:02:34 »
Do a search on this site. There's an awful lot of discussion on the subject.

Starchild

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Re: Axle Replacement for Different Gear Ratio
« Reply #2 on: April 17, 2024, 03:35:14 »
I did search and found a great deal of information that did not seem to pertain to an automatic transmission. Much of the info was about stick shifts or a 5 speed getrag with a dif change out. Lots of discussion on how to do the change and what to be aware of regarding the mechanicals but I didn't find much  of discussion regarding performance especially with the 280.   Maybe I am using wrong search terms.
 
« Last Edit: April 17, 2024, 03:45:53 by Starchild »

Peter

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Re: Axle Replacement for Different Gear Ratio
« Reply #3 on: April 17, 2024, 03:50:05 »
Under my name you can find good info about this. I have a 280 with automatic, from 4.08 to 3.27. Works fine if engine is in healty condition. The ref. decreases by 20%..

Pawel66

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Re: Axle Replacement for Different Gear Ratio
« Reply #4 on: April 17, 2024, 10:59:16 »
I would keep speedometer in mind with this kind of difference...
Pawel

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Cees Klumper

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Re: Axle Replacement for Different Gear Ratio
« Reply #5 on: April 17, 2024, 12:09:01 »
I had this axle swap done many moons ago (I reckon 20 years ago) as my car is a 1969 US spec 280SL automatic which means 4.08 rear diff ratio originally. I too was unhappy with the high revs at speed and since it was a daily driver at the time I wanted to lower them. I had a 3.69 put in which lowered revs by about 10%. The car is still plenty quick off the line for me and I love the lower rpms at speed. For me it has been a great improvement. Have not adjusted the speedo gear which now reads too low. Remember that if you want to burn rubber you can always start with the selector in '2' and it will take off in first gear, then 'upshift' as it acellerates. Or press the acellerator all the way through the kickdown switch and again it will take off in 1st gear.
Cees Klumper
1969 Mercedes 280 SL automatic
1968 Ford Mustang 302 V8
1961 Alfa Romeo Giulietta Sprint Coupe 1600
1962 FIAT 1500S OSCA convertible
1972 Lancia Fulvia Coupe 1.3
1983 Porsche 944 2.5
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GM

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Re: Axle Replacement for Different Gear Ratio
« Reply #6 on: April 17, 2024, 18:57:44 »
Gary
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Ed Riefstahl

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Re: Axle Replacement for Different Gear Ratio
« Reply #7 on: April 18, 2024, 23:07:05 »
Greetings,
I'm always interested in what others are doing to their cars.
A year a half ago I was faced with a rear axle decision out of necessity, due to a broken yoke in the differential.

I own a complete 1970 280SE parts car. However i learned quickly that nothing much on a 108 is easily interchangeable with the 230 SL's. So, I decided to rebuild my original 4.08 axle, as apposed to using the 108 and switching to rear disk brakes etc.
It wasn't until I had the axle back in the car that I discovered the torque converter had failed causing the axle failure, according to Mark at Sun Valley.

As it turned out I couldn't use the 108 transmission in the 230SL either. So, I purchased a reman from Sun Valley and kept my original. Much to my surprise, it now starts out in 1st gear. The rebuild is out of an older, compatible sedan. I personally have never cared for the way my SL stared in 2nd. I'm super pleased with the way the car drives and shifts now, going through all 4 gears. To me, it's much nicer to drive, but that's just my personal preference.

I said all of the about to say this. Since I did all the rebuild on my car, I can't help wondering how the taller gears in the rear, with a transmission that starts in 1st would be? To me, for an automatic, that could be the cats meow.

However, 30 years later, I still miss the stick I had in my first 230SL. I even considered the conversion on this 230. I sure envy the guys that have the 5 speeds.

Keep us posted on what you decide to do.
Ed Riefstahl

1966 230SL (Ms Magoo) Horizon Blue
1970 280S (Miss Daisy)
1999 BMW Z3 5 speed
1991 BMW 318I 5 Speed
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rwmastel

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Re: Axle Replacement for Different Gear Ratio
« Reply #8 on: April 28, 2024, 02:56:23 »
... I can't help wondering how the taller gears in the rear, with a transmission that starts in 1st would be? To me, for an automatic, that could be the cats meow.
Starchild, Ed, and others,

To each their own, everyone has a personal preference, and what one person finds enjoyable another will find annoying.  Just because someone says it's great, doesn't mean you'll like it.  You must experience for yourself the setup you're considering.

Attend the Group events and ride in other people's cars.  It's a great benefit of membership.  I once got to drive a Mechatronic Pagoda at PUB, and decided moden upgrades were not for me.  First hand experience is essential before making a decision on changing the drive train, suspension, or whatever.
Rodd

Did you search the forum before asking?
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RAY

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Re: Axle Replacement for Different Gear Ratio
« Reply #9 on: April 28, 2024, 09:50:20 »
Mine is a US Spec 1969  280 which had a 4.08 rear axel which I had swapped out for a 3.46 and have not regretted it for a moment. At the time I didn't want to "go all the way" to a 3.27 but sometimes now I think maybe I should have. I think maybe your biggest dilemma will be as to what ratio to go to.

I did it mainly for quieter motorway driving which we do more of than town driving but also as a by product of the lower revs it gives better mpg also, always around 26 - 27.

Pulling away from a standstill on the level, I would say, is still fine, the only time it suffers is if you are on a steeper gradient and then I just select '2' and it is fine.

My speedo has not yet been recalibrated, still looking for someone reliable in the UK to do that which is proving impossible at the moment, but shows about 12mph low at a true 70mph so have to be careful about that for the time being.

Davek1

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Re: Axle Replacement for Different Gear Ratio
« Reply #10 on: April 28, 2024, 12:33:51 »
I swapped out my 4.08 axle for a 3.27 one last year, best thing I have done. I have a good engine so no problems.
The only time that I use the manual 1st gear is when pulling away on a hill, which is no biggy. There is also a fuel saving as the revs are dropped by 20%. The whole job I did over a couple of weekends. I have not recalibrated my speedo as I could at the time not find anyone to do it. I have now got use to doing the maths in my head.

roberhofer

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Re: Axle Replacement for Different Gear Ratio
« Reply #11 on: May 04, 2024, 06:47:32 »
As per Cees Klumper, I too have done the conversion from 4.08 to 3.69. As I have the 230 SL with less torque thus I was worried to go the 3.27 route.
I do not regret it. It still drives off well from standstill and reduced the revs at highway speed. Not significantly but definitely noticeable. I have not adjusted the speedo to compensate.

cfm65@me.com

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Re: Axle Replacement for Different Gear Ratio
« Reply #12 on: May 04, 2024, 10:21:14 »
Hi Roberhofer,
Is the speedo adjustable?
I have installed a 5 speed Getrag and the speedo is under reading by about 10-15 kmh.
Chris
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Cees Klumper

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Re: Axle Replacement for Different Gear Ratio
« Reply #13 on: May 04, 2024, 10:53:32 »
I believe there are different size plastic or nylon gears inside the speedometer that can be swapped out to adjust to the different differential gear ratios.
Cees Klumper
1969 Mercedes 280 SL automatic
1968 Ford Mustang 302 V8
1961 Alfa Romeo Giulietta Sprint Coupe 1600
1962 FIAT 1500S OSCA convertible
1972 Lancia Fulvia Coupe 1.3
1983 Porsche 944 2.5
1990 Ford Bronco II