Swap Transmission Tail Cones??? - PeachParts Mercedes-Benz Forum

mach4 · #1 12-27-2011, 03:06 PM

I'm wondering if there is any issue in swapping tail cones on a 722 transmission?

I want to use the tail cone from a 722.312 (380SL) on my 722.416 ('85 300D Cali version) on my engine swap project.

This will allow me to keep the electric speedometer for one thing.

Is it literally a bolt on swap?

And if so, do I need to source a new gasket, or can I safely use this stuff?

DeliveryValve · #2 12-27-2011, 03:11 PM

My hunch it won't fit. .3 trans casings are different from the .4.

.

mach4 · #3 12-27-2011, 04:30 PM

Quote:

Originally Posted by DeliveryValve

My hunch it won't fit. .3 trans casings are different from the .4.

They look very similar, but obviously the small differences can make all the difference.

mach4 · #4 12-27-2011, 07:39 PM

This document seems to imply that many of the parts for a 722.3x and 722.4x transmission are the same - http://www.ganzeboom.net/images1/ganzeboom/parts/Mercedes/722.3,%20722.4.pdf

Here's the tail cone portion

But there are some obvious external things that are different - for example the tail cones and the neutral safety switch.

I tried to look up the parts on Fastlane and see if the gasket was the same part number for both transmissions which would be a pretty strong indicator that the two tail cones could be swapped, but I didn't find these on the site.

ROLLGUY · #5 12-28-2011, 11:31 AM

I put a trans from a 1985 300D in a 1981 300SD (electric speedo) and found out that the tail cones looked the same, but were different. I had to get a tail cone and related parts from a later 124 trans that had the electric speedo. I still have the parts in a box awaiting time to install them. I can take photos for you if that would help, or even look for a part number on the casting.....Rich

mach4 · #6 12-28-2011, 12:00 PM

Quote:

Originally Posted by ROLLGUY

I can take photos for you if that would help, or even look for a part number on the casting.....

That would be great if you wouldn't mind. I'd like to understand what's going on inside that make them not swappable. There will be others that will be facing similar situations I'm sure.

mach4 · #7 01-11-2012, 03:12 PM

Quote:

Originally Posted by ROLLGUY

I put a trans from a 1985 300D in a 1981 300SD (electric speedo) and found out that the tail cones looked the same, but were different. I had to get a tail cone and related parts from a later 124 trans that had the electric speedo. I still have the parts in a box awaiting time to install them. I can take photos for you if that would help, or even look for a part number on the casting.....Rich

Quote:

Originally Posted by DeliveryValve

My hunch it won't fit. .3 trans casings are different from the .4.

Yup, won't work.

Thanks for the head's up.

Dave Donaldson · #8 01-11-2012, 06:08 PM

Cheers will follow your posts, just bought a 722.317 from a 300 td 1987 for my 87 300 SDL,, hoping to install it some day,, BUT , I have since found out via fourms that the 722.317 has a cable speedo and my SDL has a digital speedo,, ooops , I haven't crawled up under my car yet to see the trans id number, ( book says it's a 722.361 ) - 5 C,, here,, but I hope that I can do some kind of parts swap to go digital, if not may have to trade it or sell it,, 110,000 miles po said it was fine uhmmm. PS
if you have any more diagrams on these trans please e mail or post ,me I have no info source but the forms ty and cheers

update found that the 722.321 is in the 87 SDL as per the charts the 722. 321 was only used on 86 and 87 300 SDL,,, uhmmm

ROLLGUY · #9 01-11-2012, 08:49 PM

I will try to get a photo of the electric speedo tail cone I have that is from a 124 trans. I have been out of town, but will be back on Friday and I can take a photo....Rich

mach4 · #10 01-12-2012, 03:50 PM

According to this document http://amtrans.nl/mercedes.pdf, my available options to find an electric speedometer for a 722.4xx transmission, would be the following:

The 190s are all mechanical from what I can tell. Most of the 300 diesels are mechanical from what I can tell, the possible exception being the 300SD?? Looking at clusters on dBay to see what have mechanical connections vs electrical, I have deduced that the following appear to provide the best possibility of finding a rear housing with an electrical speedometer that will bolt to my 722.416

C220 94-96
C280 94-96
300SE 89-91
300SEL 88-91

Any other insight in where to look?

Graplr · #11 01-12-2012, 05:30 PM

Is the only/main reason to swap tail cones to have an electrical speedometer? If so there are products that convert the signal. I checked into it 4 years ago or so. Don't remeber specifics. I believe Brian Carleton has done this or at least knows more than I.

mach4 · #12 01-12-2012, 06:54 PM

Quote:

Originally Posted by Graplr

Is the only/main reason to swap tail cones to have an electrical speedometer?

Essentially yes. If I can swap the tail cones then the speedometer will be completely stock. Since it is already calibrated to the lower rear end I won't have to fiddle with new gears in the speedometer to get it to be accurate. I also won't have to punch a hole in the firewall and I'll have a completely electronic system. I also won't have to swap instrument clusters.

It's just a cleaner solution all around if I can find one that will work. If one is available it is an 8 bolt + 1 nut swap.

Graplr · #13 01-12-2012, 07:53 PM

Quote:

Originally Posted by mach4

Essentially yes. If I can swap the tail cones then the speedometer will be completely stock. Since it is already calibrated to the lower rear end I won't have to fiddle with new gears in the speedometer to get it to be accurate. I also won't have to punch a hole in the firewall and I'll have a completely electronic system. I also won't have to swap instrument clusters.

It's just a cleaner solution all around if I can find one that will work. If one is available it is an 8 bolt + 1 nut swap.

Well if you can't find a transmission that will work or tail cone that will swap, I know there is a electrical device that will take the mechanical signal and convert it to an electrical one. I was told it costs around $100. May be a simple fix for you and you can use you current 300D trans. I believe the mechanical sender hooks up to it and then it sends electrical pulses out to the speedometer. If you want to take this route PM Brian Carleton and see if he still knows where you can source one.