5 spd VS 3.27 rear

[zak]

For excitement I have been reading past copies of The Star Magazine. I came across an article by Pierre Hedary on the advantages of converting your rear end to 3.27. Pierre was doing so by changing out the gears in a stock 3.92 rear to the 3.27 ratio.
Then there was another article where a well known restorer had his 280 SL installed with a 3.27 rear from a 280SE 4.5 for his Florida retirement. ( Paul Russell ? , Alex Finnegan ? ) and his was an auto trans. Both articles centered on the ease of hi speed hiway driving and the savings of rpms.
Then I read the post of Dan Caron speeding across Canada in his 230sl 5 spd.

Some criticize the 4 spd manual trans and especially first gear as " agricultural " . I was wondering if the install of the 3.27 rear lengthens all gears so you could wind out first and second more and would it improve the overall 4 spd experience ,plus allowing high speed highway driving in relative quiet ?
Also, am I incorrect in thinking that in the getrag 5 spd, 5th gear is really an overdrive and does not effect the lower gears ?

jz

[Chris Long]

I recently installed the 6 speed trans on my 4 speed manual and enjoying it; The first 4 are the same ratio as all the stock box giving it an identical driving experience yet hit 5th / 6th and now driving an highway speeds is a breeze.

6th on highway can almost be too high as revs drop to mid 2's at 75mph which doesn't have enough for hills / gradients but on the flat it's great. Even having 5th and dropping revs to 3's is great.

Very happy with conversion and the 4 speed is in the roof should the next owner (when i'm composting) want to go backwards...

[Cees Klumper]

I went from a 4.08 (US spec) differential to a 3.69 in my automatic 280 SL and that's done the trick for me. No trouble maintaining highway speeds comfortably at around 80 MPH. (Even clocked 115 MPH once). The engine likes to rev and it's ok to accept that and not fight it.
Of course, if you want to that's ok too.

[JamesL]

I find that much above 85 the screaming of the engine spooks me a bit. I'm auto/3.46. Brain knows it's OK, but my gut suggests otherwise.
To overcome this problem,  I use noise cancelling headphones

[zak]

BTW, Alex Dearborn was the restorer/ Florida retiree I was trying to remember who swapped in a 3.27.

So there were a lot of rear end ratios.
4.08, 3.92 , 3.69 , 3.27. Were these of all available as Pagoda options ?
I was hoping that someone with a 4 spd who made the rear end swap would chime in. I am interested in hearing how 1,2 and 3 gears are affected and for good or bad.

jz

[Benz Dr.]

BTW, Alex Dearborn was the restorer/ Florida retiree I was trying to remember who swapped in a 3.27.

So there were a lot of rear end ratios.
4.08, 3.92 , 3.69 , 3.27. Were these of all available as Pagoda options ?
I was hoping that someone with a 4 spd who made the rear end swap would chime in. I am interested in hearing how 1,2 and 3 gears are affected and for good or bad.

jz

There was also 3.75 used on230SL's but that's a dum brake rear axle. 3.27 was never a Pagoda option and is best used on standard transmission 280 SL's.

[zak]

Dan, you think the 3.27 is not a good choice for my 250 sl 4 spd ?
Not enough power ?

jz

[Benz Dr.]

The 280SL and the 4.5 sedan have very similar power to weight ratios. The 250 will handle it with a 4 speed and a fresh engine. I prefer the 5 speed with the smaller displacement engines and it gives you a final drive ratio of about  3.45 in fifth gear which is right in the power band. I would NOT use the 3.27 in anything with auto trans.

[MikeSimon]

Dan makes an excellent point of looking at different issues than just cruising rpm. You have to consider that our SLs were designed by engineers in Europe, having mostly driving over there in mind.
European engines historically differed from US ones inasmuch that they made horsepower from rpm and US ones made horsepower from displacement/torque.
The set-up with given transmission and rear-end ratios put the engine in the best power band at most road speeds. If you lower the engine rpm by changing the final drive ratio, your engine may operate in a not so efficient and useful range. The worst thing as far as con-rod bearing loads is low rpm and full throttle.
I know, in the U.S. we love to loiter around in the car at 3000 rpm. That is fine for a V8 with a red-line of 5500. A European engine constantly operated under heavy load at low rpm may see significant stress.

[zak]

Maybe I will just get larger diameter tires next time.
That will lengthen the gearing a bit.

jz

[H. Keith Henry]

My 280SL automatic was fitted with a 3.27 rear end when it was restored 20-some years ago. I've owned the car less than 12 months, so I was obviously not able to drive it before the conversion to compare before and after with the same car. But I can say that my first experience driving a 280SL at interstate speeds many years ago was such a turn-off for me, with all the noise and fuss, that I decided I didn't want a Pagoda after all. I was told that the "noise and fuss" was because of the gearing of the rear end. Fortunately, years later, I had a more pleasant experience with a differently-geared Pagoda and changed my mind. With my car, I wouldn't mind a little more acceleration at times, but -- once properly tuned -- it passes fine and meets my expectations for a 52-year-old cruiser. My opinion.

[Shvegel]

I installed 3.27 gears in my original housing in my 280 and I love it.  My car is an automatic and from time to time it feels like it is lugging so I just push the shifter forward a notch and drop it into a lower gear.

[Peter]

I installed 3.27 gears in my original housing in my 280 and I love it.  My car is an automatic and from time to time it feels like it is lugging so I just push the shifter forward a notch and drop it into a lower gear.

Same for me, I’m very happy with the 3.27. I installed, in case off, the “kick down button” also on the center console, but I never needed it. The engine has been overhauled, it think that’s important before changing over to 3.27.

Peter

[teahead]

If you have a stick shift, definitely go w/a 5 or 6-speed while keeping the rear end me thinks.

Having an automatic myself, I'll be looking for a 3.69 gear set.   Is that all I need?  Just the ring and pinion?   No need to swap out the whole rear end?  Or do I still?

[Jonny B]

I believe there have been previous discussions about the change in differential ratios.

Try the search function, it can be your friend.

[ggdtr5]

Hi there, I have a U.S. spec 280SL 4speed manual with a 3.27 diff and I find it great. The revs are certainly reduced especially when driving on the motorway. I regularly drive from UK to Europe on the motorway i like to sit around 3000-3500 revs and I’m doing about 80-85 mph. Noise levels are good too- can still have a conversation.. I’ve travelled with other pagodas on the motorway and they are above 4000rpm at this speed.
Regards Graham

[Todd]

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[dakman29]

Dan Caron did a rear end swap for me in my 68 280 four speed. The differential I got through Dan is a 3.27 limited slip. This is my second Summer driving season after the change and I have only positive things to say. That is after owning my car since 2005. In addition to dropping rpm’s on the freeway I have not felt any loss of acceleration.

[roberhofer]

Similar to Cees Klumper, I had a US spec 4.08 on a 230SL and got a 3.69 rear axle.
This brought the highway revs down a bit without slowing the car too much otherwise. Definitely happy with the change.
Side benefit: Now have read disc brakes (vs. standard drums on 66' 230 SL).

[Peter]

relation: revs - transmission - speed