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Automatic to 5 speed manual conversion

44K views 359 replies 25 participants last post by  MrSpock 
#1 ·
Purchased a 5 speed Getrag 717.400 from Euro and should be here by the middle if the month. Fonzi found it on the W126 forum, and the great guy
That he is, he text me the thread. I jumped on it and it will be shipped shortly.

Everthing seems to be in the kit however, what about the driveshaft.
Is the one in my automatic ln my 85 euro 280sl going to work,
I dont know if the automatic has a longer driveshaft than the manual.

If I need to get whichever end modified ( shortened) then i need the length required. I will order a new clutch disk and throughout bearing ifanyone knows the part nrs that i will need.

What else should i prepare for. A kit to rebuild the slave clyinder or get a new one.
 
#260 ·
I read most everything in the tech data specs but never found anything that quoted the rear differential gear ratio.

But then i probably overlooked it. Ill try google

I am pretty sure most 280sl cars have a 3.59 differential. I think the earlier ones were higher.

Automobile-catalog.com has the specs on pretty much every car and the data seems very reliable.
 
#262 ·
Mercedes-Benz 280SL (107 E28) Technical Specifications by goole explain it easily and all on one page.

Rear diff 4 spd manual and auto. 3.69:1

Manual 5 speed. 3.92:1



5 speed manual gear ratios

1: 3.96:1

2: 2.34:1

3: 1:43.1

4: 1.00:1

5: 0.88.1

If the numbers are important, be sure to check the years as:
1) the differential was defefinitely lower on later years 3.69--> 3.58.
2) the early d-jet five speeds (1974-76) are slightly different in the ratios than the later five speeds (1981-85).
Text Font Line Number Document
 
#263 ·
I switched from auto to 4 speed, gave up looking for a 5
Wish I had done it 20 years ago
Did have to shorten a driveshaft & have it balanced
Absolutely no issues
( except maybe removing flywheel bolts )
Have put about 100K on it so far
Only minor item, would like a taller # rear diff
Enjoy
 
#267 ·
I have put over 500 miles on the car. Its amazing how different the car handles with the 5 speed manual.
I just returned from a 82 mile drive to visit my dermatologist to have some places on my face and ears fozen.
Stopped in costco for some baby back ribs for this coming weekend. Im surprised on how better the gas mileage
Is with a 5 speed manual. I am very happy with my choice of making theconversion.

Anyone need a very good automatic with 75k miles on it.
 
#268 ·
The six cylinders should have all come with stick shift rather than auto. they are a lot more fun that way. Sports car and roadster both sound like fun but can be deflated with an auto. my 300e with 5 speed is the most fun i have in a four door car. It makes my other 300e's seem plain and lacking. You will not regret the change only that you didn't do it sooner.
 
#269 ·
Quote:
Originally Posted by nobby View Post
I find first gear real short so the new gears might help that. I find second gear a little long....so maybe the new gears might fuck that up. I wouldn't want to mess with 3rd gear as I find that one the best one....kinda like your favorite club in your golf bag. After that....doesn't really matter..........you'd be up to speed at that point.

For the type of driving I do...........the switch to lower gears would be a good one.....probably gain 5 mpg with the change.
My 1st is also short, 2nd up to 50 mph, 3rd is also very good. I find driving to town there is only a couple long flats where I get to 4th.

What speed versus rpm do you show at 70 and 80 mph.

Today i finished installing my towbar. Only left is to cut the slots is rear bumper valance and install the rear bumper.

Took a 150 mile drive round trip to King City in "Maggie". On the 101 freway at 70 Mph in 5th rpms are 2800
At 80 Mph, Rpms were 3200. At 90 mph Rpms were 3500. Average fuel mpg was around 22.5 mpg
 
#271 ·
Took a 150 mile drive round trip to King City in "Maggie". On the 101 freway at 70 Mph in 5th rpms are 2800
At 80 Mph, Rpms were 3200. At 90 mph Rpms were 3500. Average fuel mpg was around 22.5 mpg
I'd like you to put a GPS on that....or tell me what gears in the rear you are using.
 
#270 ·
Today I found myself winding out 1st and 2nd, and then already being at speed and being able to drop into 5th (skipping third and fourth). But you can probably do the majority of your driving in 2nd and 3rd, and 4th is 1:1 just like a four speed, good for highway "driving", whereas 5th is just for fuel economy or highway "cruising".
 
#273 ·
One of my Sl books show the gear ratios as follows for 280sl (1980 thru 1985)
4 speed automatic.
1. 3.68. 2:- 2.41---3:-1.44----4:-1.00 and R:-5.14

Rear final drive ratio 3.58:1

5 speed manual 280Sl. !(1981-thru 1985)
1:-3.82---2:-2.20----3:-1.40----4:-1.00---5:-0.81.....R:-3.71
Final drive ratio:--3.58:1
 
#276 · (Edited)
That's right, but I think I recall researching that trans with Dennis and seeing that the ratios were the same which lead is to believe it was the same, interchangeable transmission. Of course this thread has proven that the rear cone is different. But thanks to @nobby for pulling the cone off that trans he has.
 
#278 ·
The 1983 280sl 5 sp manual wrecked in dublin ohio was picked up at 2 pm central time and is its way to calif via kentucky
Where it will be stored in my daughters garage until i can take the time to go get it. If i didnt have this $&@)(;:/)$&@ chest
Cough and feeling shitty i would leave today. No salvage title, so im going to repair it. I have all the parts except a grill.
I assume that the 450 SLC front clip parts will fit the 280 SL.
 

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#282 ·
The 450 SLC is a 1974.

Ill be using all the front parts plus the hood and passenger fender. Depending on the extent of damage to the passenger side euro headlight, may need parts, although I do have a spare set of euro headlights on the shelf which does not have the vacuum pods.

Pull the hood off, remove passenger fender, remove front bumper and pull the engine out is my overall plan.

I have no doubts whatsoever as to repairing this car to put it back on the road.
 
#289 ·
Mike, My tires are 225/50/R16

This wensday is amazon prime black friday. I will look for a good deal on garmin GPS units. I am still "down in the weather" with this
Chest cough to where i cant drive with the medication I am now taking. Hopefully I will find a good dash cam also.

Anybody got any recommendations on units they have installed in their car.
 
#290 ·
Mike, My tires are 225/50/R16



This wensday is amazon prime Black Friday.

I have a few GPS I don't use anymore and could send you. My wife and I use our iPhones and they have Speedometer Apps, and it's one less thing to plug into the car.

What kind of phone do you have Dennis?

Having 225/50/16 tires actually makes your rpm readings look very accurate mathematically. My RPMs do show significantly higher at those speeds, but I can't explain exactly why. I don't know if either my speedometer or tach are correct. I'm about to take a drive and I will check the accuracy of my speedometer with my iphone app. The screen looks like this:
Auto part Screenshot Font Technology Speedometer


Since it's a free app, occasionally ads like this show up:
Auto part Technology Screenshot Games Speedometer
 
#291 ·
I have the Samsung notebook3. Ill look to see if the app you are showing is available for my phone.

If i find a gps i like i will install it in my car. I perfer to buy one, so i can get one that is easy for me.
I actually looked at a dash cam by garmin that Has bluetooth and GPS, that shows your speed.
It may be all i want and need.

Thanks for the offer.
 
#298 ·
Fuel pump relay ? I was driving back home from eye doc visit today
And while doing 60 on hwy 46, my car died. I downshifted to 4th, then to 3rd,
And finally to 2nd and the jolt when releasing the clutch Started the engine.
Kinda like pushing a strait shift to start it with a low battery. Ran ok rest of way
Home. Searched under the hood and nothing loose. Reading threads just now
Points out could be the FPR. Nobby stated his above the fuse box on passenger side
And his is a 280sl. I will pull that side panel and see if its there.

Any way to test it on the bench?
 
#302 ·
Big shots with 5 speeds, my car is around 4100rpm at 80mph or so, just checked, so we're talking about 600-700rpm between the cars which must make up for the 3-4mpg difference at highway speeds.
 
#312 ·
Rcvd my new Garmin Gps today. 4 hours later i have the latest software installed.
Will hardwire the multi powerport gizmachie tomorrow. Should be ableto take it for a cruise
This weekend and check my speed against the RPM and speedo for verification
To accuracy
 
#313 ·
The gps and my speedo are rite on. You cant see a hair difference from 50 up to 85. I made a costco run this morning
With my trailer in tow. Works like a charm. Max load us 350 lbs. raised the lid and put the big case of Charmin ( its softer
On my butt) inside with 2 boxes of k-cup coffee, a couple bottles of 1800 tequila, some jars of margarita mix,
a big ass santa maria tri tip, 2 slabs of baby back ribs (3 to a package), a blue tooth speaker to see if it will in the back
of my car, big bag of trail mix, couple of watermelons, and veggies.

Bar-b-que this weekend with some friends from camarillo, the pontoon boat is sittin in the lake tied up to a float,
Ready to do so motorboatin. Will make a cooler full of margarita jello shots, tonite.
 

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#335 ·
Yesterday I made a great cruise from my place here on Lake
Nacimiento in Paso Robles down to Oxnard CA to sign escrow
closing paperwork on my house. Finallly Sold !!

Maggie and the trailer parked at FRY's electronic superstore in Oxnard CA
I bought myself my XMAS present. Since I m a widow, I buy myself
something I want every year for XMAS that is different from the ordinary.

I purchased the best Drone that Fry's had. Comes equipped with Camera
and 25 to 30 minutes of flying time. Looking forward to XMAS this
year.
 

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