1st gear start for auto?

[Buz]

Is there a way to make the 280SL start in 1st gear every time with the selector in 4? We had a 1982 300SD that staeeted in 2nd unless kucked down and a 1982 300TD that always started in 1st gear which I preferred.

[mdsalemi]

Buz,

Anything is possible, I'm sure.

But why on earth would you want to do this?  1st gear on a W113 automatic is so low as to be nearly useless.  I have never used it except to verify that it is there and working.

Maybe it was put there for climbing the Alps with a full load, but in practical driving it has NO use whatsoever.

Michael Salemi
1969 280SL
Signal Red 568G w/Black Leather (Restored)
President, International Stars Section
Mercedes-Benz Club of America

[thelews]

quote:Originally posted by mdsalemi

1st gear on a W113 automatic is so low as to be nearly useless.
 
 Michael Salemi

It's used for stump pulling.

John
1967 Early 250 SL Red/Caviar, Manual

[mdsalemi]

quote:

It's used for stump pulling.

John
1967 Early 250 SL Red/Caviar, Manual

I knew that!  That's why I said NEARLY useless, not COMPLETELY useless!  I pull stumps all the time with my car!  Yep, just wrap a big old honkin chain onto the special fitting welded onto the bumpers.

Michael Salemi
1969 280SL
Signal Red 568G w/Black Leather (Restored)
President, International Stars Section
Mercedes-Benz Club of America

[Mike Hughes]

quote:Originally posted by mdsalemi

Buz,

Anything is possible, I'm sure.

But why on earth would you want to do this?  1st gear on a W113 automatic is so low as to be nearly useless.  I have never used it except to verify that it is there and working.

Maybe it was put there for climbing the Alps with a full load, but in practical driving it has NO use whatsoever.

Michael Salemi
1969 280SL
Signal Red 568G w/Black Leather (Restored)
President, International Stars Section
Mercedes-Benz Club of America

I bet first gear might be a bit more useful if one transplanted a really low ratio axle to seriously drop the highway revs!

- Mike Hughes  -ô¿ô-
  1966 230SL Auto P/S
  Havanna Brown (408)
  Light Beige (181)
  Cream M-B Tex (121)

[rwmastel]

If you start off in 1st using the kick down switch, it is of little use as your car accelerates so well.  If you use the gear selector to start in 1st, it's not bad.  I do that from time to time, with my 3.75:1 differential.  I imagine a 3.27:1 differential would be very acceptable for this.  Now that I think of it, I drove Tom Sargeant's 280SL (Tunis Beige) at PUB 2007 and I believe it was customized just like this.  Automatic transmission, first gear start, 3.27 rear end.  Very nice!!

Rodd
Pagoda Technical Manual
please contibute: http://www.sl113.org/wiki/pmwiki.php
1966 230SL
2006 C230 Sport Sedan

[hands_aus]

remember Arthur Dalton? What ever happened to him?

He at one point mentioned a modification that could be made to the electrical circuit of the 3 position solenoid on the auto transmission. Apparently a push switch could be inserted in the circuit. It was mooted for the purpose of starting in 1st gear after installing a 3.27:1 rear axle. Probably easy to do?

Anybody remember this? Naj, Michael Salemi?

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[mdsalemi]

Maybe Mr. Dalton is taking the winter off.  Let's hope he's OK.

Rodd is right about the electrical switch on Tom's car.

But, if you change the rear axle ratio and then "modify" the transmission for a first gear start you have a very different vehicle in terms of driving, acceleration, etc.  I can't say there's much wrong with the setup having seen it and driven it as well.

But that's a very different question than simply a first-gear start as the thread originated with.

Michael Salemi
1969 280SL
Signal Red 568G w/Black Leather (Restored)
President, International Stars Section
Mercedes-Benz Club of America

[hauser]

I believe Gernold has performed this modification before.

I believe Arthur Dalton is spending most of his online Mercedes time with Mercedes Shop.

1969 280sl 5 spd
Gainesville, Fl.

[hands_aus]

Hauser,
Thanks for the feed back.

I had a look at the circuit and a parallel switch to the kick down switch would do the job.

Have a look here for the basic wiring sytem and information about adjusting the transmission
http://www.mercedesdismantlers.com/16BoltInstallationInstructions.html

The value of not using the kickdown switch every time is that you need to have the accelerator at full throttle for this to work.

The value of using a separate switch is that it operates the solenoid at low engine revs which means the car can be driven at normal acceleration.

The negative of this arrangement is that it is MANUAL and needs to be chosen every time the driver want to use it.

Speculating here but I think a relay? could be added to the circuit adding 'everytime functionality'.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[Shvegel]

Keep in mind if you do this electrically you will change the shifting charachteristics of the transmission(High RPM and hard shifts). Your transmission will always think you are flooring the accelerator and will act accordingly. Remember the three position solenoid adjusts control pressure in the transmission as well as allowing for a first gear start.

To do this properly requires someone to do a little rework in the hydralic passages to allow the first gear start without changing the control pressure. I bought one of the hydraulic diagrams of the transmission years ago to do just that but it turned out to be for the wrong transmission.

[psmith]

I just shift it myself like an automatic stickshift because unless I really have my foot on it, it shifts a little too soon.  However, first is very short and it goes to second pretty fast unless you stomp on it.

Pete S.

[TheEngineer]

Here's the application: In West Seattle, where I live, we have a very steep road from the beach up to the cliff where my residence is. About one third up, there is a four-way stop, where I make a left turn. I find it useful to shift into first as I coast to stop. I have a 3.27 rear axle. The car accelerates very nicely up the hill and sometimes - when there is a BMW behind me - I push it a little and don't shift out of second. There are some tight curves as well and so far - nobody has passed me, or even come close.

'69 280SL,Signal Red,Automatic,retired engineer, West-Seattle,WA

[Richard Madison]

Peter (the engineer):

You'd have quite a challenge getting from the beach to the cliff in a manual shift car...probably have to move down to the beach or walk up.

Richard M, Manual Tranny (in mostly level country)

[TheEngineer]

Richard: Years ago - when I was young - I had a blue 230SL with manual shift and, I think, a 3.69 rear axle. It was a blast to drive. This particular stretch of road is so inviting to take fast: It is steep and has curves and some bumps too. I have never seen a cop there with a radar gun, probably because most people would drive that stretch slowly. But the road is quite wide, there are sidewalks and you can see kids or dogs and because it is so steep, you could slow down real quick. I'm sorry now, I sold the 230SL, but I got $4500.- for it and only paid $3k. It's a **** to get old: Just had an angioplasty.

[mdsalemi]

quote:Originally posted by theengineer

 It's a **** to get old: Just had an angioplasty.

Pete, we all hope you are doing well.  As they say, getting old isn't for sissies.

Michael Salemi
1969 280SL
Signal Red 568G w/Black Leather (Restored)
President, International Stars Section
Mercedes-Benz Club of America

[Buz]

The 4.10 is very buzzy on the highway but I would not be happy with the torque of the second gear starts if I swapped to a 3.69 or 3.27 rear end.