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
  #16  
Old 08-12-2014, 07:56 PM
compu_85's Avatar
Cruisin on Electric Ave.
 
Join Date: May 2008
Location: La Conner, WA
Posts: 5,234
My SDL has a 2.86 IIRC. I've often wanted something a bit taller, but thought the V8 rear end would be a bit too much.

I'd love to drive a car with the V8 rear end in it some day.

-J

__________________
1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.
Reply With Quote
  #17  
Old 08-12-2014, 08:22 PM
vstech's Avatar
DD MOD, HVAC,MCP,Mac,GMAC
 
Join Date: Mar 2006
Location: Mount Holly, NC
Posts: 26,835
Quote:
Originally Posted by compu_85 View Post
My SDL has a 2.86 IIRC. I've often wanted something a bit taller, but thought the V8 rear end would be a bit too much.

I'd love to drive a car with the V8 rear end in it some day.

-J
most every 603 powered car I've seen has the 2.65 rear gears. I'd bet yours does too.
__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
Reply With Quote
  #18  
Old 08-12-2014, 09:38 PM
Registered User
 
Join Date: Sep 2005
Location: ottawa, ontario, canada
Posts: 256
My thoughts are fix everything else first, the easy stuff before you tackle the bigger jobs like a diff swap. Things like injectors and fuel quality can have a major influence on mpg, timing (chain stretch and start of injection), low rolling resistance tires/narrow tread on the road (there is a big difference 185 vs 215 width). I knew many owners who absolutely flogged their S classes back in the day at 90mph constantly before there was any concern over speeding, fuel prices or traffic flow. Those cars lived long lives and the owners never complained about the fuel economy going down. I seem to remember 30mpg (USA) being very easy at any speed so long as you stayed out on the highway.
My point is they were built to run hard-they can take anything traffic today wants to dish out. 3500+ rpms not a big problem. It is up to you to decide if can afford to fuel it, and keep it running in top shape.
Running a 2.47 diff would certainly require everything to be in good shape like pump calibration and timing, I have driven some with stock diffs and they could not make a left turn without getting run over! Each car is different...
Reply With Quote
  #19  
Old 08-12-2014, 10:34 PM
mach4's Avatar
Registered User
 
Join Date: Jul 2011
Location: San Diego County, CA
Posts: 2,736
Quote:
Originally Posted by t walgamuth View Post
mach4 has the 247 in his 107/617 swap I think and tops 30 mpg. I'd think one would top 30 with regularity with the 247 though it would be pretty doggy off the line.
Correct. Only one tank in the last 31 fills have been under 30 (that one happened to be 29.8)

My car weighs in probably right at 3400 while the 126 weighs a bit over 3500. I've got a bit of a weight advantage and probably have a bit of an advantage in the drag department too, but I think 30 is doable in a 126 with a 2.47 rear end if you drive sensibly and keep the speed down a bit. Many would likely find the performance in my project a bit less than desirable, but I find it entirely acceptable (perception is reality). I built the car for open road cruising, not tearing up the streets.

By the way, here's an annotated BMEP chart showing the calculated speed and mpg to hopefully make a little more sense of things.

The road load would likely not change measurably with a 2.47 rear end, but the rpms would drop for each speed thus increasing the mileage. I turn 2100 rpm at 60 mph, just for reference.

Attached Thumbnails
Optimizing an 82 300SD For Modern Highway Driving-300sd-bmep.jpg  
__________________
Current Stable
  • 380SL (diesel)
  • Corvette C5
  • Manx
  • Baja Bug
  • F350 Powerstroke
  • Auburn Boattail Speedster replica
Reply With Quote
  #20  
Old 08-12-2014, 10:46 PM
mach4's Avatar
Registered User
 
Join Date: Jul 2011
Location: San Diego County, CA
Posts: 2,736
Quote:
Originally Posted by JamesDean View Post
The transmission's final drive is 1:1 right?

With 3.07 stock
70 MPH = 2832 RPM

With 2.88
70 MPH = 2657 RPM

With 2.47
70 MPH = 2280 RPM

That 3.07 number sounds a little low. I seem to remember about 3,000 at 70..hm
That's likely calculated with a direct drive transmission, with an auto you'll have an extra 200 or so.

Using the automatic option on the mph vs rpm calculator shows exactly what you remember

Attached Thumbnails
Optimizing an 82 300SD For Modern Highway Driving-300sd-mpg3.jpg  
__________________
Current Stable
  • 380SL (diesel)
  • Corvette C5
  • Manx
  • Baja Bug
  • F350 Powerstroke
  • Auburn Boattail Speedster replica
Reply With Quote
  #21  
Old 08-17-2014, 04:40 PM
Registered User
 
Join Date: Jan 2009
Location: N.W. In.
Posts: 609
differential

How do you know what differential you have? I have an 85 300SD was wondering if I have the 3.07 or the 2.88.
Reply With Quote
  #22  
Old 08-17-2014, 04:56 PM
Mölyapina's Avatar
User title not in use
 
Join Date: Oct 2012
Location: Chelmsford, Massachusetts
Posts: 4,373
Quote:
Originally Posted by yuke View Post
How do you know what differential you have? I have an 85 300SD was wondering if I have the 3.07 or the 2.88.
I think it's stamped on the side of the diff as part of the part number. The 1985 would have come with the 2.88.

I think the 3.07 runs 3000 RPM at 70 MPH, so if yours runs less than that at 70, it's a 2.88.
__________________
"Senior Luna, your sense of humor is still loco... but we love it, anyway." -rickymay ____ "Your sense of humor is still loco... " -MBeige ____ "Señor Luna, your sense of humor is quite järjetön" -Delibes

1982 300SD -- 211k, Texas car, tranny issues ____ 1979 240D 4-speed 234k -- turbo and tuned IP, third world taxi hot rod

2 Samuel 12:13: "David said to Nathan, “I have sinned against the Lord.” And Nathan said to David, “The Lord also has put away your sin; you shall not die."
Reply With Quote
  #23  
Old 08-17-2014, 05:21 PM
Registered User
 
Join Date: Jun 2004
Location: West of Ft. Worth. TX
Posts: 4,186
It's normally stamped on the lower left rear corner of the differential (looking at the cover plate side). If you have a "resilient center piece" Differential where the rear differential mount is to one side, it may be on a data plate located on the lower right rear corner.
__________________
Sam

84 300SD 350K+ miles ( Blue Belle )
Reply With Quote
  #24  
Old 08-17-2014, 09:32 PM
vstech's Avatar
DD MOD, HVAC,MCP,Mac,GMAC
 
Join Date: Mar 2006
Location: Mount Holly, NC
Posts: 26,835
All the diffs I have checked have the number stamped into the carrier frame on the passengers side near the cover plate. On the flat machined portion.
__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
Reply With Quote
  #25  
Old 08-18-2014, 10:18 AM
Registered User
 
Join Date: Jan 2009
Location: N.W. In.
Posts: 609
I could not find the stamping but I do run about 2850-2900 rpm at 70 mph so I guess I have the 2.88 rear. What I did quickly notice while the car was jacked up was a nail in tire peeved me off as tires only have 10,000 on them also took notice inside on both is wearing harder then outside any thoughts as what could be causing this? Oh well plugged the tire and will rotate them shortly to front.
Reply With Quote
  #26  
Old 08-18-2014, 10:20 AM
vstech's Avatar
DD MOD, HVAC,MCP,Mac,GMAC
 
Join Date: Mar 2006
Location: Mount Holly, NC
Posts: 26,835
how much do you keep in your trunk? it's possible you have bad springs... or it could need an alignment.
__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
Reply With Quote
  #27  
Old 08-18-2014, 04:56 PM
Registered User
 
Join Date: Jan 2009
Location: N.W. In.
Posts: 609
Vstech I sometimes do have a lot of xtra weignt in rear but took care of that with HD. springs and thicker pads underneath the springs it sits real nice. Was wondering if the subframe bushings might be shot? Seems the top of the tire is toed in. My front are wearing just opposite so for now I will just rotate them. I did recently have it lined up also. 85 350SD (260,000) maybe more odometer was broke for awhile running strong.
Reply With Quote
  #28  
Old 08-18-2014, 07:06 PM
Mölyapina's Avatar
User title not in use
 
Join Date: Oct 2012
Location: Chelmsford, Massachusetts
Posts: 4,373
Quote:
Originally Posted by yuke View Post
HD. springs
HD springs or shocks? I hadn't heard of HD springs for the W126.
__________________
"Senior Luna, your sense of humor is still loco... but we love it, anyway." -rickymay ____ "Your sense of humor is still loco... " -MBeige ____ "Señor Luna, your sense of humor is quite järjetön" -Delibes

1982 300SD -- 211k, Texas car, tranny issues ____ 1979 240D 4-speed 234k -- turbo and tuned IP, third world taxi hot rod

2 Samuel 12:13: "David said to Nathan, “I have sinned against the Lord.” And Nathan said to David, “The Lord also has put away your sin; you shall not die."
Reply With Quote
  #29  
Old 08-18-2014, 07:10 PM
JamesDean's Avatar
Electrical Engineer
 
Join Date: Apr 2005
Location: NE Ohio
Posts: 5,038
Quote:
Originally Posted by Jooseppi Luna View Post
HD springs or shocks? I hadn't heard of HD springs for the W126.
They exist, go peek some of the other parts supplies and you'll see "standard" and "hd." Its really just a notch higher in the spring part numbers. The spring your car got if you had lots of points in their spring picker system thing.
__________________
Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out.
Check here for compatibility, diagnostics, and availability!

(4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!)


82 300SD 145k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k
Reply With Quote
  #30  
Old 08-18-2014, 07:11 PM
JamesDean's Avatar
Electrical Engineer
 
Join Date: Apr 2005
Location: NE Ohio
Posts: 5,038
Quote:
Originally Posted by yuke View Post
Vstech I sometimes do have a lot of xtra weignt in rear but took care of that with HD. springs and thicker pads underneath the springs it sits real nice. Was wondering if the subframe bushings might be shot? Seems the top of the tire is toed in. My front are wearing just opposite so for now I will just rotate them. I did recently have it lined up also. 85 350SD (260,000) maybe more odometer was broke for awhile running strong.
Certainly possible. My dad's 300SD's were shot. Might also want to check your differential mount too.

Also carefully inspect your lower control arms for rust, holes, etc. Be sure to check the spring and shock mount areas too. I've replaced like 3-4 of them now due to rust.. My buddy's 300SE had a bad one and the one wheel cambered in at the top.. Yours might not be the case but still does not hurt to check.

__________________
Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out.
Check here for compatibility, diagnostics, and availability!

(4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!)


82 300SD 145k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k
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 06:23 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2024 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page