Hi all,

I am fitting a manual transmission on a Mercedes euro 5.0 liter engine. Its designation is M117.960, develops 275 hp (SAE) and 296 lb-ft of torque.

These engines never came with a manual transmission so I am using a flywheel, clutch, bellhousing and gearbox out of a euro ’72 W116 Mercedes 350 SE, which is nearly a direct bolt on. These cars used a 3.5 liter M116.980 engine with 230 hp (SAE) and 211 lb·ft of torque.

I’m looking for a clutch kit. I contacted the MB ClassicCenter and all 3.5 clutch components are not available for now. Further, I’m a bit worried by the 40% torque increase of the 5.0 compared to the 3.5 engine and am wondering if the stock 3.5 clutch can handle it.

By searching on the web, I found that Spec and AutoCom are offering clutch kits that could fit my project :

http://www.specclutch.com/cars/Mercedes/300/1972/Single

http://www.thepartsbin.com/catalog/?N=1668+11149+4294963078+9191

Spec in particular is interesting because they offer performance clutches that may be able to handle the 40% torque increase. The only problem is that Spec offers that clutch for the W109 4.5 that never came with a manual transmission. So I’m wondering what flywheel I’m supposed to use and if this would be a direct bolt on for my application.

On their side, AutoCom comes with the same reference for 3.5 and 6.3 engines which makes me worry a bit as the latter never came with a manual transmission. So before going any further, I thought I would ask for opinions :

- Would the stock MB 3.5 clutch be able to handle the 296 lb-ft of torque of the euro 5.0? (I attach below the specs of that clutch as described in the workshop manual) If yes, this is the easiest way to go, as long as parts become available again soon.

- Does anyone have any experience with Spec or AutoCom products?

Is there any other supplier out there for 3.5 clutches?

Another solution is to have my clutch elements rebuilt and have the pressure plate beefed up in the process. Anyone knows who can do that, preferably in the US, or anywhere else?

Thanks in advance!


Below are the characteristics of the clutch used on 3.5 engines these cars are the following, as per the Mercedes workshop manual (I translated all from metric into American system):

Clutch Thrust plate (pressure plate) designation : Fichtel & Sachs MF 240 Sph
Mercedes part number : 001 250 77 04
Contact pressure : 1675 – 1852 lbf
Throwout path on thrust ring : 0.354 + 0.040 inches
It is worth noting that the flange on which the pressure plate bolts on the flywheel is in recess of 0.150 + 0.040 inches (towards engine) compared with the clutch surface area, as shown on the first attached picture.

Driven plate (clutch disc) designation : Fichtel & Sachs 240 GSD
Mercedes Part number : 002 250 32 03
Thickness of driven plate with no pressure : 0.407 +/- 0.018 inches
Thickness of driven plate under pressure : 0.366 +/- 0.12 inches
Thickness of lining : 0.157 inches
Quality of lining, both sides: Textar 50 s/17 (don’t know if there is any metric involved here)
Torsion Damper Impact torque pulling end : 253 lb-ft
Torsion Damper Impact angle : 4°
Friction torque : 18 – 22 lb-ft
I measured the diameter of the disc and it seems to be in between 9 3/8 inches and 9 7/16 inches. The center of the disc accommodates a 10 teeth shaft and outer diameter of the center hole is 1.024 inches.

Attached Thumbnails

   

I can't help with your clutch selection, but please keep us updated as your project progresses!

__________________
Glen Tokuhara
Beauty & the Beast and the wagon that could!

I looked up a 116 350SE in the EPC and got a completely different picture.

There are two different disk repairs kits and two different pressure plates, depending on the chassis number.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

The first pressure plate has been replaced by the second one, as noted on EPC. They are in back order, meaning that they are out of stock and that the manufacturer has to manufacture new ones. The Classic Center doesn't know how long it will take. As per the repair kits, you will see that they are no longer available by clicking on the blue link on EPC.

... should have looked at the note.


Also, the EPC shows 010 250 31 03 as a disk, and that one does not show NLA.

Is the existing pressure plate bad? Generally those last for a long time. I pulled one out of a 107 280SL with 225K on it and it was like new.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

Yes, I may look into that. The surface of the pressure plate is bad, it would need surfacing. More importantly, I would like to have the diaphragm spring modified or replaced to increase pressure to cope with the additional torque.

I talked to someone at SPEC and the clutch they list for the 4.5 is a 228 mm diameter while the one I have is a 240mm. But they said they may be able to rebuild/strengthen the one I have. I need to send it to them to see what they can do.

Try Ron Parker at German Star Mercedes Parts (http://germanstar.net)
(800) 377-6598. he had a pressure plate for $219 a couple of years ago compared to $300++ at MB dealer. He did not have plate and suggested to reline that locally if needed.

Personally, I would just try the stock 3.5 components first and see what happens. If torque is an issue, disk will simply slip/wear out faster and you can go to special mods. Getting the tranny out is not such a big deal for replacement of clutch.

Bert

__________________
'70 111 280SE/c 3.5 (4 spd manual) - sold
'63 MGB
'73 MGBGT V8

first try to find a setup which fits and works, you can get the pressure plate uprated, and run a different type of clutch disc material for more bite if needed at a later date. if you are worried uprate it before you put it in, ring local performance clutch shops and they might be able to put you in cotact with a clutch builder, also have a look around online for a shop in the u.s.

I already have the setup that fits and works: the 3.5 flywheel and clutch is a direct bolt on, and I had to modify the two top holes in the bellhousing which now fits OK. I may go as recommended by Bert: first try stock, and then uprate if needed. I was trying to avoid getting the trans out at a later stage, but uprated non original material also has its risks.

I called Ron Parker and he doesn't have any of the parts. I called Rusty of Buymyparts and he quoted me the parts. I wonder if he gets this stuff at the same source as MB in which case he may also be in back order.

uprating most parts have risks/
i would have thought a bigger worry would be the gearbox holding the torque,
so do u have a dual mass flywheel, or sprung clutch disc?
and does the transmission have an overdrive gear? because if it does this may be your weakest link

The gearbox is a 4 speed with the 4th having a 1:1 ratio. It may be weak, for the 41 kg of torque. I will try it as is. I guess if anything goes wrong it will be the bearings. If that happens I wonder if I can fit reinforced bearings. The flywheel looks quite standard, I do not know what a dual mass flywheel looks like. The clutch disk also looks standard, with springs to absorb torsional vibrations.