W123 tech specs req'd - wheelbase length - PeachParts Mercedes-Benz Forum

Stretch · #1 07-22-2010, 05:05 PM

Dear All,

Does any one out there know the technical specifications in terms of a tolerance for a W123 sedan / saloon wheel base?

MBeige posted a great picture with the dimensions 2795 mm but I expect there is a +/- limit on this length. See:-

T124 (wagon) ride height?

I'm in the middle of adjusting the caster on my front suspension and I want to check that the dimension between the wheel centres are not getting too big.

I hope some one out there can help!

Stretch · #2 07-23-2010, 08:53 AM

I've found this but it doesn't have the tolerances:-

http://www.carfolio.com/specifications/models/car/?car=189090#a_dimensions

whunter · #3 07-23-2010, 05:04 PM

http://wikicars.org/en/Mercedes-Benz_W123
Production 1976-1985
Wheelbase Sedan: 2795 mm (110 in)
Coupé: 2710 mm (106.7 in)

http://en.wikipedia.org/wiki/Mercedes-Benz_W123
Mercedes-Benz W123
Manufacturer Daimler-Benz
Production 1976–1985
Total production: 2,696,915 built[1]
* 4-door: 2,397,514
* Coupé: 99,884
* Estate: 199,517

Assembly Sindelfingen, Germany

Predecessor Mercedes-Benz W115

Successor Mercedes-Benz W124
Class Executive car

Body style(s):

4-door saloon
2-door coupé
5-door estate

Engine(s):

2.0 L I4
2.2 L I4 Diesel
2.3 L I4
2.4 L I4 Diesel
2.5 L I6
2.8 L I6
3.0 L I5 Diesel
2.0 L I4 Diesel

Transmission(s):
3-speed automatic
4-speed automatic
4-speed manual
5-speed manual

Wheelbase Sedan: 2,795 mm (110.0 in)
Coupé: 2,710 mm (106.7 in)
Length Sedan: 4,724 mm (186.0 in)[2] (euro-spec bumpers)
Width Sedan: 1,784 mm (70.2 in)[2]
Height Sedan: 1,435 mm (56.5 in)[2]

Vehicles Mercedes-Benz E-Class

http://www.the-blueprints.com/blueprints/cars/mercedes/7543/view/mercedes_benz_240d_lwb_w123_1977/

http://www.the-blueprints.com/blueprints/cars/mercedes/5074/view/mercedes_benz_240d_lange_1974/

http://www.the-blueprints.com/blueprints/cars/mercedes/7570/view/mercedes_benz_280ce_c123_1977/

http://www.the-blueprints.com/blueprints/cars/mercedes/7566/view/mercedes_benz_280e_w123_1977/

http://www.the-blueprints.com/blueprints/cars/mercedes/13608/view/mercedes_w123/

Stretch · #4 07-24-2010, 02:53 PM

Great information but surely Mercedes gave a tolerance for these wheel base lengths?

I mean when you adjust the camber or the caster on the front suspension (or on the rear for that matter) you move the centre of the wheel to a different position - thus not all W123s sedans will have a wheel base of exactly 2795 mm - it will be something like 2795 mm +/- say 15 mm for example.

Does anyone know this tolerance?

whunter · #5 07-24-2010, 03:54 PM

Quote:

Originally Posted by Army

Great information but surely Mercedes gave a tolerance for these wheel base lengths?

I mean when you adjust the camber or the caster on the front suspension (or on the rear for that matter) you move the centre of the wheel to a different position - thus not all W123s sedans will have a wheel base of exactly 2795 mm - it will be something like 2795 mm +/- say 15 mm for example.

Does anyone know this tolerance?

That is subscription data...
EXAMPLES:

http://www.hunter.com/alignment/?gclid=CMjL57vphKMCFRMeDQodIQ0yZQ

http://www.teambearusa.com/news/index.cfm?GroupID=1&Archive=1

Blackhawk
http://www.blackhawkcr.com/vehicle-dimension-data.asp

Mitchell Vehicle Dimensions Manual
https://www.mitchell.com/mitch/products/product.asp?pf_id=29

http://www.alignmentspecs.com/

http://www.autodata.ltd.uk/product.asp?prod=Wheel_Alignment_Data_2010

MBeige · #6 07-25-2010, 02:26 AM

Quote:

Originally Posted by Army

Great information but surely Mercedes gave a tolerance for these wheel base lengths?

I mean when you adjust the camber or the caster on the front suspension (or on the rear for that matter) you move the centre of the wheel to a different position - thus not all W123s sedans will have a wheel base of exactly 2795 mm - it will be something like 2795 mm +/- say 15 mm for example.

Does anyone know this tolerance?

It's probably a few cm's at most.

The caster calls for probably a 1.5 degree range. I doubt the front wheel moves forward that much.

Some dimension figures are also for Euro spec models with smaller bumpers. US dimensions are longer due to the larger US bumpers.

Stretch · #7 07-25-2010, 04:23 AM

Quote:

Originally Posted by MBeige

It's probably a few cm's at most.

The caster calls for probably a 1.5 degree range. I doubt the front wheel moves forward that much.

Some dimension figures are also for Euro spec models with smaller bumpers. US dimensions are longer due to the larger US bumpers.

Yeah I thought so. That's why I put +/- 15mm as an example... there must be a tolerance some where for normal use - in other words for adjustments - and not accident damage.

MBeige · #8 07-25-2010, 04:49 AM

You don't measure caster by the wheelbase, you measure it depending on the caster angle. From there the wheelbase difference is a secondary piece of info.

Once you've adjusted them properly, then use that secondary info to compare, but don't use it as a baseline reference point.

Stretch · #9 07-25-2010, 05:32 AM

Quote:

Originally Posted by MBeige

You don't measure caster by the wheelbase, you measure it depending on the caster angle. From there the wheelbase difference is a secondary piece of info.

Once you've adjusted them properly, then use that secondary info to compare, but don't use it as a baseline reference point.

I know - I'm measuring it by measuring camber when the wheel has been turned by 20 degrees. This is standard practice.

My only problem is that I'm probably trying to adjust to an incorrect value of caster as the wheel base is getting too long. I'm now at 2810 instead of 2795. BUT even so the 2795 value must have a tolerance on it.

I'm asking for the correct value of caster here

W123 Caster / castor settings for a sedan / saloon?

layback40 · #10 07-25-2010, 06:04 AM

Hope this helps army !! I dont know where its from, but it does give the specs.

Good Luck !!

Stretch · #11 07-25-2010, 06:48 AM

Thanks fore the PDF layback - I'd already found it - it does give a caster specification but I'm unsure if it is the value for straight ahead with the MB special tool - OR - for the 20 degree wheel lock method (this has a smaller number).

I think I'm going to have to make a guess at the setting. I'm at 7.6 degrees of caster (measured by 20 degree wheel lock method) but the wheel base is still longer than the 2795 prescribed length...

Hmmmm

Gilly · #12 07-25-2010, 07:20 AM

I HAD a collection of TDM's (Technical Data Manuals) and those things list just about any dimension or spec a person would need. I have ONE left which is a 1975, which of course pre-dates the 123 chassis, but figured it wouldn't hurt to look to see if they listed some general spec on variation in the wheelbase. They list the wheelbase dimension as being "R" (they have various length checks, especially diagonal ones, for checking after an accident I'd assume), but no where do they list any spec for "R" or a variation. In an introductory section they do list the wheelbases for the various chassis, with no other info, and nothing in section 40, which is rims and tires, which is where they list all the chassis specs.
I would also assume it should be within a few mm's. If the frame is straight and control arms and trailing arms not damaged, I don't know why it wouldn't be. You are concerned about the caster angle, which is good, but if the frame is straight, I don't know why one side would be seriously different than the other.
I don't know what you have available that you are checking this with, but a modern alignment machine will give the thrust angle, once you get everything aligned, see what the thrust angle is, if everything is in spec and the thrust angle near zero, then i don't know if I'd agonize over a difference in wheelbase.
Gilly

Stretch · #13 07-25-2010, 07:48 AM

OK thanks - I've got the caster to be within 0.3 degrees of each other. And the wheel base length is the same on each side.

I've made other measurements to check the integrity of the chassis - and I'm happy that everything is as straight as it should be.

I think I'll reduce the caster a little bit to bring the wheel base a little closer to 2795 and then call it a day. I'm about to do a 12 hour drive next week so I'll have plenty of time to be critical of my decision!

MBeige · #14 07-25-2010, 12:36 PM

You would want a higher caster - the straight measurement on mine when I had an alignment was around 8.3 deg. To give you a better picture, the wheel was closer to the front edge of the wheel well arch than previously, where the caster was 6.x degrees.

This is how mine is right now after alignment.

It might not be too obvious here, but if you compare mine (yellow/beige w123) to the others the positioning of my wheel is not as it was above (this was prior to the alignment). Other w123s beside me had better caster, their front wheels were more forward in the wheel well than mine.

Stretch · #15 07-25-2010, 01:09 PM

Thanks MBeige there is indeed a great difference before and after...

If I can get the rest of the car finished I'll give it a quick test drive first before reducing what I've got. I'm now practiced enough at replacing UCA and LCA bushings anyway if I've got it really wrong!

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