Are 124 transmission interchangeable? - Page 2 - PeachParts Mercedes-Benz Forum

babymog · #16 08-30-2016, 12:05 PM

If you're looking for more off-the-line, look into some changes to your turbo and IP, you'll spin the tires with your stock gears.

400Eric · #17 08-30-2016, 01:27 PM

Yes, I'll be doing that stuff (and more), but right now I need to address this needing-a-trans issue, and I might as well do a first gear upgrade while I'm at it, with a much more readily available trans.

Do you have a build thread for your OM603 car that I could learn from? Are there any others? I've actually been looking and all I can find is crazy turbo-sticking-out-of-the-hood kind of builds. I'd eventually like to have this car running low 14s but for now low-15s will do. Twelves are not needed here. Even GSXR doesn't seem to have a build thread anywhere. A lot of good info on his site, yes, but no actual build thread. A general internet search just produces the crazy stuff.

I also want to mention that in another thread I talked about how I proved that the fuel pump relay does indeed affect the shift points at WOT on my CIS-E cars. This proved that it wasn't just the bowden cable, modulator, governor, and valve body controlling the shifts. How would a trans that comes from such a car be controlled here?

Is there anybody here who has actually done such a swap?

I blazed my own trail when I hopped up my 400E. I had to be the one who did everything for the first time cause nobody else had ever done it before. I can't afford to be a trailblazer here. OM603s are too expensive and too hard to find.

babymog · #18 08-30-2016, 02:37 PM

I don't know of a build thread however, Dave (and later I also) did chronical some of his build here: OM603 semi-super pump testing, fitted with Bosch 6.0mm elements

and another member posted some of his updates here: OM603, 722.6, and W124 adventures!

There are others who have made changes to the 603-powered cars at different levels, these are the ones that come to mind first.

400Eric · #19 08-30-2016, 03:04 PM

Thanks big time for those links Jeff!!

Still need to hear from OM603 owners who are running a gasser 722.3 trans.

Frank Reiner · #20 08-30-2016, 03:04 PM

Quote:

Originally Posted by 400Eric

I also want to mention that in another thread I talked about how I proved that the fuel pump relay does indeed affect the shift points at WOT on my CIS-E cars. This proved that it wasn't just the bowden cable, modulator, governor, and valve body controlling the shifts. How would a trans that comes from such a car be controlled here?

And a link to that thread, if you please.

400Eric · #21 08-30-2016, 03:27 PM

OK Frank here are the two posts where I documented my findings on the matter:

http://www.peachparts.com/shopforum/performance-paddock/245997-tuning-cis-21.html#post2792781

http://www.peachparts.com/shopforum/performance-paddock/245997-tuning-cis-21.html#post2793540

This Fuel Pump Relay discussion occurred as part of a larger discussion on tuning CIS-E cars. If you have the time, go ahead and read the whole thread after my first link. Lots of heady stuff in there if you are into CIS-E cars! In fact, better yet, read the whole thread from the beginning!

tjts1 · #22 08-30-2016, 03:50 PM

I have a good 87 300d trans that was rebuilt by the previous owner sitting in my garage. I swapped it out for a 5spd.

400Eric · #23 08-30-2016, 03:53 PM

I'm re-reading that thread myself and according to Dave in the first paragraph of this post: Tuning with CIS on the 300D my klima relay controls the WOT shift point so hopefully the new gasser trans will obey the 300D's klima relay and shift earlier for it's new diesel partner. It would be nice if that issue is solved that easily. That Dave. Even when he's not around he helps.

Anybody out there actually done a swap like this?

400Eric · #24 08-30-2016, 03:55 PM

Quote:

Originally Posted by tjts1

I have a good 87 300d trans that was rebuilt by the previous owner sitting in my garage. I swapped it out for a 5spd.

Can I come clean out your garage for you?

Frank Reiner · #25 08-30-2016, 08:04 PM

Quote:

Originally Posted by 400Eric

On the 300D my klima relay controls the WOT shift point so hopefully the new gasser trans will obey the 300D's klima relay and shift earlier for it's new diesel partner.

Since the Klima relay controls the power supply to the Kickdown (KD) switch, when the set speed (RPM) is reached, power to the KD circuit is interrupted, causing an upshift. The KD circuit simply does not know the provenance of the transmission.

400Eric · #26 08-30-2016, 10:23 PM

Could a defective Klima relay prevent an otherwise healthy trans from shifting into fourth gear and delay up-shifts in the other gears? If I could get to the bottom of this tranny's funky behavior I might not need to swap in another trans. I'm studying other threads on this topic as we speak and I'm trying different things. TBH, this trans seems too healthy and strong to be replaced. It's as if something (like a defective relay or kickdown switch) is telling it: "don't shift yet".

Frank Reiner · #27 08-30-2016, 10:49 PM

Quote:

Originally Posted by 400Eric

Could a defective Klima relay prevent an otherwise healthy trans from shifting into fourth gear and delay up-shifts in the other gears? If I could get to the bottom of this tranny's funky behavior I might not need to swap in another trans. I'm studying other threads on this topic as we speak and I'm trying different things. TBH, this trans seems too healthy and strong to be replaced. It's as if something (like a defective relay or kickdown switch is telling it: "don't shift yet".

No, the relay is a power supply to the KD circuit; a fault in the relay that cut off power to the KD circuit would result in early WOT shifts.
A fault in the KD switch, or in the "B" switch in the gear selector, that caused the KD solenoid to be energized, would result in late shifts.

400Eric · #28 08-30-2016, 10:52 PM

Please tell me more about the "B" switch.

Frank Reiner · #29 08-30-2016, 11:10 PM

4E:

Most selectors for the 722.3xx transmissions that start in 2nd have a notch to the right of the "L" position. The lever can be pulled back to the "L" position, and then pushed to the right, causing the trans to shift to 1st. Pushing the lever to the right closes a parallel circuit to the KD solenoid. In effect, it is a hand operated KD switch.

Stretch · #30 08-31-2016, 12:33 AM

I think the 722.6 is a bit bulkier (size-wise) and might need modification to the chassis to make it fit whereas I don't think that would be necessary going from 722.4 to 722.3 on a W124