Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Diesel Discussion

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 01-23-2018, 12:22 PM
Shadetree
 
Join Date: Jan 2010
Location: Back in SC upstate
Posts: 1,481
Speedometer/trans/differential question.

When I inquired about which speedometer to use on the diesel into a gas body I was persuaded that in order to get a proper reading on the speedo I'd have to use the speedo from the diesel car.

Both cars are early w126 and I wanted to use the differential from the gas setup because I like the gear ratio. Now I read on the thread about differentials that in order to use the gas differential I'll need to use the gas speedometer to get an accurate reading.

The diesel engine and transmission came from an 84 300SD and went into a 85 380SE body. The original differential got a yoke change to accommodate the diesel drive shaft.

Which speedometer will work? If neither with this setup what should I do to fix it short of changing the differential?

__________________
84 300SD
85 380SE
83 528e
95 318ic
Reply With Quote
  #2  
Old 01-23-2018, 01:11 PM
sixto's Avatar
smoke gets in your eyes
 
Join Date: Jun 2000
Location: SF Bay Area
Posts: 20,793
I don’t think it’s as much gas vs Diesel speedometer as keep the speedometer with the differential. In the W126 series, the speedometer is set to the differential ratio.

Sixto
98 E320s sedan and wagon
Reply With Quote
  #3  
Old 01-23-2018, 01:18 PM
Shadetree
 
Join Date: Jan 2010
Location: Back in SC upstate
Posts: 1,481
Quote:
Originally Posted by sixto View Post
I donít think itís as much gas vs Diesel speedometer as keep the speedometer with the differential. In the W126 series, the speedometer is set to the differential ratio.

Sixto
98 E320s sedan and wagon
I could have sworn someone told me I'd have to change the rear housing on the transmission if I wanted to get the gas speedometer to be accurate.

So to achieve accurate readings I should use the speedometer from the gas setup with the gas differential?
__________________
84 300SD
85 380SE
83 528e
95 318ic
Reply With Quote
  #4  
Old 01-23-2018, 01:34 PM
sixto's Avatar
smoke gets in your eyes
 
Join Date: Jun 2000
Location: SF Bay Area
Posts: 20,793
If you’re talking ‘84 SD transmission into ‘85 SE body then all you need is for the speedometer to match whichever differential you’re using (3.07 from SD or 2.47 from SE). The SD transmission should have the same speedometer drive as the SE transmission. It’s a W123 transmission that needs conversion from gear drive to work with a W126 speedometer. Does the SE have traction control?

Sixto
98 E320s sedan and wagon
Reply With Quote
  #5  
Old 01-23-2018, 02:08 PM
Shadetree
 
Join Date: Jan 2010
Location: Back in SC upstate
Posts: 1,481
Yes, the SE has a wire coming from the differential which is absent on the SD. Is that traction control? If so, how is it going to work without the electronics of the gas ignition?
__________________
84 300SD
85 380SE
83 528e
95 318ic
Reply With Quote
  #6  
Old 01-23-2018, 03:34 PM
sixto's Avatar
smoke gets in your eyes
 
Join Date: Jun 2000
Location: SF Bay Area
Posts: 20,793
That’s more likely the ABS speed sensor which isn’t associated with speedometer or engine function. If the SD differential doesn’t have an ABS speed sensor, you might have a persistent warning light at best and intolerable brake function at worst. I don’t know if you can disable ABS by just unplugging the module or pulling a fuse.

I’m not familiar with traction control of that vintage but it would likely involve hydraulic components like a tandem pump and pressure lines to the differential.

Sixto
98 E320s sedan and wagon
Reply With Quote
  #7  
Old 01-23-2018, 04:21 PM
Shadetree
 
Join Date: Jan 2010
Location: Back in SC upstate
Posts: 1,481
The brake lines run through a module on the left front fender well just in front of the brake master cylinder. It seems since the wiring is there for the differential and all the rest of the brake system is intact it may work as it should.

__________________
84 300SD
85 380SE
83 528e
95 318ic
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 10:03 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page