diesel geek poll: four speed or fiver? - PeachParts Mercedes-Benz Forum

t walgamuth · #1 12-10-2005, 08:08 PM

today the auto tranny finally gave out on the 82 300d. it was shifty from the start and i expected it not to last, but kept changing the filter and fluid and it kept getting better. but today it wont engage any gear. i will get it checked to see if it is anything simple. but...

if it isn't. i have a choice. i can put in the fiver from the ex ralley car that i have been planning to historic race someday and put the four speed in that or i can put the four speed from 240 in it that i bought for that purpose.

what do you all think?

tom w

Mitch H · #2 12-10-2005, 09:23 PM

Is the fiver an overdrive?
What's the first gear ratio?
If you've got the 3.07 or taller in the back, you likely want 4:1 or lower in the tranny.

About the auto:
Does reverse engage? (B2 piston or band if it does)
Does it engage for a tow start? (then your front pump is shot, but the rear pump works)

300SDog · #3 12-10-2005, 10:18 PM

Tom, the 5 spd will need its own driveshaft..... or shortening of an existing 240D 4-spd driveshaft. And the problem with shortening driveshafts is you'll be hard pressed to find somebody who can do the job properly leaving it ballanced and correct so it doesnt orbit. Any weirdness in the driveshaft will screw the drivetrain; it aint like an old Chevy you understand.

Somebody in Maryland on ebay was selling 123 5-spd tranny last year, parted out from a junkyard Euro model. It traded for about $500....... verrry tempting for my 240D, but I passed on the deal because the guy didnt think to snatch the Euro 5-spd driveshaft with it.

t walgamuth · #4 12-10-2005, 11:27 PM

od and first is in the neighborhood of 4. i checked. it is 3.82. and the gear in the back is presently the stock 3.08.

the auto wont engage any gear. i didnt try to pull start it cause it started fine. maybe i didnt understand your point on that.

i dont know about the ds. i may have enough odds and ends to mix and match but i suppose that will result in imbalance too. so unless i find a ds that is the right length i have a good chance of trouble. the ds from the ex ralley car wont work cause it is a sedan with a longer wb than the coupe. so you think a ds balancer and shortening shop wont be able to do a good job?

thanks for the input.

tom w

300SDog · #5 12-11-2005, 04:02 AM

The question is who's got the technology to properly ballance the driveshaft. What are they gonna do, mount it on a lathe and guestimate the spin ballance? I caint speak from personal experience, but have heard a few driveshaft horror stories. psfred who posted here got screwed on driveshaft work.

But if thats a turbo 300CD, then it might be worth it to spend the money and import a proper 5-spd driveshaft from Germany. They handicap Vintage race events and you might win a few based on having a huge diesel handicap rating. Plus the car will probably outhandle many other vehicles of the same genre, easily achieving speeds of 100+mph.

Am reminded that early '70s 280SL 6cyl won 24hr Daytona race against Porches etc. It won not because it was the fastest car, but on account of it causing the least amount of driver fatigue.

t walgamuth · #6 12-11-2005, 11:08 AM

racing the cd.

but if i ever get around to it and have some extra $$ i would like to race the ex ralley car (280e euro). haveing been flooded at least partially it isnt much good for anything else prob.

tom w

Mitch H · #7 12-11-2005, 03:44 PM

Driveline Service of Atlanta has a good reputation and advertises in the Star.
Driveline Service of Atlanta (404) 361-9111
4652B Jonesboro Road
Forrest Park, GA 30297

There's also Driveline Service of Portland in Oregon,
1-800-227-8608

It sounds like you could race the 280 with a four speed, as long as you don't need to go faster than a 1:1 ratio allows.
The 5sp O/D would be pretty much like the 240D box, with the addition of a freeway 5th gear.

I mentioned that pull start bit as a troubleshooting measure. If the tranny works when the car is moving but not at a standstill, the front pump would be the likely cause. It does sound like you have a total hydraulic failure, does it have adequate fluid in it?

t walgamuth · #8 12-11-2005, 03:50 PM

and it seems to be normal.

and that pretty much exhausts my expertise on automatics.

thanks for the input.

yeah i thought prob i could race the four speed. i will have to do some calculatoins and see if top speed is affected. wo the od gear.

tom w

Mitch H · #9 12-11-2005, 08:46 PM

In reading my post, I realize I didn't mention what Driveline Services was good for. They rebuild MBZ driveshafts. Can probably lengthen or shorten them too.

t walgamuth · #10 12-12-2005, 05:22 AM

i didnt even notice you didnt say what for...it seemed obvious.

thanks for the tip.

tom w

t walgamuth · #11 12-12-2005, 08:14 AM

of another thing it could be...the shift rod could have fallen off i guess.

another thing i know to check on the automatics.

tom w

Glinko · #12 12-12-2005, 08:21 AM

I have a 400 page book I was supposed to have read a month ago.

I am printing some spark notes right now.

engatwork · #13 12-12-2005, 07:08 PM

Quote:

Driveline Service of Atlanta

I second that - you will not find a better shop to re-build/modify and balance a MB driveshaft. If you take the I75 route you will be right there at it TW. You could drop it off on the way down and pick it up on the way back or just ship it.

t walgamuth · #14 12-12-2005, 07:59 PM

the tip, but i will be pulling my 35' trailer with my wife, son, his wife, my youngest lovely daughter and my grandson, so no benzy detours will be possible without certain death for me.... or at least dirty looks.

tom w

R Leo · #15 12-12-2005, 08:11 PM

A four speed with a 2:88 rearend wouldn't be too shabby either.

Thrash Driveshaft in San Antonio, Texas did the mods to mine when I installed the 4-speed in the wagon (see my thread on the conversion). They'll be doing the same work on the shaft that will get used in the five-speed install ...if I ever get around to it.