Philosophical Transmission Question... - PeachParts Mercedes-Benz Forum

350SL4spd · #1 10-21-2005, 12:46 PM

Burried in this post is a technical problem, but the main question is more opinion:
Car in question: 1981 380SL. 2 owner CA car, tens of thousands of dollars in receipts (including new sub frame), new very expensive paint job. 220k miles. Overall car is a very solid very babied 9/10. Engine and trans are out, engine is getting 100% rebuild.

Car clunked loudly dropping into reverse (and not as loud into drive but noticable) before the drivetrain was pulled.

Flex disks are newer and definitly not the source of such a loud clunk. Diff mount is suspect and will be changed w/ the flexs. Center link was replaced last year.

My Question:
There is a slight possibility that the clunk is in the tranny (well, 50/50 btw that and the diff, really). Now w/ the damn thing out and already sitting on the shop floor, should it be eliminated as a possible suspect for this loud clunk? I would hate to put the new motor in and then have to pull the tranny again! But I am also nearing the end of my budget...
And the time is nigh for decision making!!

What would you do?

JBoggs · #2 10-21-2005, 12:58 PM

About a month ago it got worse, pulled the transmission pan and found bits of clutch material in it. I changed the fluid and got worse finally failed with large chucks clutch coming off. Just had the tranny rebuilt-$1200 and it seems fine but now I have a drivetrain noise that just cropped up.

If you want to do it yourself, drop the pan. look for trash and that should tell you if you need to look further at that.

Good luck.

JB

jhodg5ck · #3 10-21-2005, 11:07 PM

i'd have the trans checked while it's out.. Double work is never much fun.

Any modifications/warming up being done while the motor is out?

The 380's in Euro spec can be a good time

Jonathan

t walgamuth · #4 10-22-2005, 01:05 AM

my 500sec. i think it is the reverse clutch pack. but on the other hand in 50k it has not gotten worse. it is caused by putting it in reverse while rolling forward.

tom w

t walgamuth · #5 10-22-2005, 01:14 AM

the po.

tom w

350SL4spd · #6 10-22-2005, 12:25 PM

Quote:

Originally Posted by jhodg5ck

i'd have the trans checked while it's out.. Double work is never much fun.

Any modifications/warming up being done while the motor is out?

The 380's in Euro spec can be a good time

Jonathan

Wish I could do something else to her! I don't know what's different about the euro specs engines other than lack of a cat. They have a higher compression (9.0 as opposed to an 8.3:1) which would be what, longer rods? Tougher heads? I frankly don't have the time to try and sqeeze a turbo/super in that tiny engine bay either!

The old girl made it a solid 220k miles the first time around, and I'm only rebuilding the engine because the heads needed to get done (smoked bad) and the rest of the car was so perfect. The silica cylinder sleeves look great, but the carbon on the pistons is scarry!
I'd love to make her a stick shift, but it'd take forever to find all the parts....

jhodg5ck · #7 10-22-2005, 04:39 PM

Actually, there is quite a bit that can be done.

The US spec piston have a Huge dish in them to lower compression, as Euro piston looks more like a conventional piston sans the dish, with that in mind 10-1 slugs are available.

The Euro spec cams bring the redline up around 62-6500 if I remember. The exhaust is a Far better design (essentially cast headers) giving a true dual sytem.

I have also read that the Euro spec heads have different ports, but have yet to physically inspect them myself.

The short of it is you go round 140 ish HP to right about 200..and upwards of that could be easily seen going w/ a custom/hotter grind on the cam.

If you are sticking w/the US motor it begs to have a blower installed..compression as low as that could take an Easy 7-8 lbs.

Speaking of stick, I'm working at getting all the neccesary bits to install a richmond 5 (or possibly 6) speed in a 126 Coupe...

Jonathan