How much HP and torque can the rear axles handle?

[g1979]

New to the forum, first post. But I being following this forum for some time.
I'm doing a restoration modification on a 250SL with a conversion to V8 engine
And I don't know if the rear axel can handle it?
I know this type of restorations are not everyones cup of tea,nbut I'll appreciated any help.
Thank you

JV

[badali]

The rear end can not handle the HP.  Get the complete drive train from a 4.5 parts car if you are installing a V8.

[GGR]

Getting a rear end from a 4.5 is a good idea, as the 3.27 ratio will do better than the SL one.

The weakest part is the sliding joint, and the sliding sleeve inside it. All sliding sleeves are the same, make sure to get one which is not cracked. Try to get a sliding joint out o a 6.3 (some 4.5 also have it) as they are stronger.

Apart from the sliding joint and the ratio, all parts are the same, so they are at leat able to take 250hp and 51 kg of torque like the 6.3. I guess torque is more a problem that power.

What kind of V8 are you fitting? If an MB 3.5, 3.8, 4.2 or 4.5, your rear end will do fine, even without the reinforced 6.3 sliding sleeve. But you may need it with a 5.0 or 5.6.   

[ja17]

The 3.27 rear diff from the 4.5 is quite different. The main casting, ring gear and pinion gear are physically larger size. This increase handles the added torque better. The yoke casting which holds the spider gears is also larger.  The problem is the pin which holds the spider gears will wear it's bores in the yoke and the holes may become oblong in the 3.27 rear diffs. Be sure to check this on all used 4.5 diffs before installation. 

The 3.27 unit basically fits up fine and looks the same with the exception of the metal u-tube which will need to be removed before installation.

[GGR]

I did fit an LSD diff carrier out of a 4.08 into a 3.27. So they are interchangeable. Same width, and the 3,27 ring gear fitted just ine on it . I also believe the housings are the same, but one should check on EPC to be sure.

[ja17]

If your research the subject further you will find that the W108 280SE, SEL 4.5,  3.27 diff and gears are definitely a different size from a standard or posi W113 diffs. and are not interchagable.  Possobly the gears out of some  air suspension cars(W109.057   300SEL 4.5)  may have a small housing 3.27 diff. but the axle assembly will only accommodate non-air suspension cars. However, in theory these300SEL 4.5  small 3.27 gears could be set up in a standard W113 diff housing.

[GGR]

I checked into EPC: there are several part numbers for the center housing. all of them are specific to the 4.5 but one which is also shared with the 3.5. The diff carrier is common with the 6 cylinder engines though, this is why I was able to fit an LSD out of a 4.08.

So, Joe is right: ring gear, pinion and housing are different on the 3.27, and may be able to handle torque better.