Gen2 permanent First Gear Start mod possible? - Page 2 - Mercedes-Benz Forum
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post #11 of 22 (permalink) Old 03-31-2018, 09:20 AM
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Originally Posted by mramay View Post
I have a Bergwerks FGS box on my 560SEC and while it's fun, it wouldn't be fun full time. I have a 3.07 limited slip diff and 245/40/18 tires on the car, and it spins the tires too easy to leave the FGS running all the time. Take off medium easy and when the revs get up just a little, the tires spin but that happens going around corners too. Probably could use better quality tires to stay hooked up longer. Highly recommend the H&R lowering springs and new front Bilsteins to keep it controllable.

My 560SEL is close to stock and even with 235/45/17 tires, it can still spin them on a first gear start. The 560 engine has a ton of torque!!

I wish my 420SEL did that haha. The car is pig even giving good throttle in 1st. It may take a while to get there, but nothing cruises like a W126 at high speed.
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post #12 of 22 (permalink) Old 03-31-2018, 09:40 AM
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So the 420 starts in first gear?


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post #13 of 22 (permalink) Old 03-31-2018, 11:03 AM
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They all start in second I think. I know they do over here.
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post #14 of 22 (permalink) Old 03-31-2018, 01:04 PM
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Both of mine start in 2nd gear

Some days it's just not worth chewing through the restraints
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I'm surprised that NOBODY has asked me what this is / means
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LOL
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post #15 of 22 (permalink) Old 04-01-2018, 01:52 PM
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Im trying to find the hydraulic circuit diagrams for the 722.3 trans in my piles of paperwork. I have diagrams for each fluid path for each gear for the trans.

Reason I want to look at them is because, from a stop, the kick down solenoid only needs to be quickly triggered (less then 1sec), for it to command the trans into first gear, it will hold first gear and shift to 2nd based on the boden cable/throttle position. It acts like a normal trans, normally it will upshift to 2nd @ around 10-15km/h. It will hold 1st gear forever if the kick down solenoid stays continuously triggered, in my case for standard day to day driving, I only want it to quickly trigger the kick down solenoid for a short time when at a stop, then let the trans upshift as it feels.

Why does this matter?

Well the kickdown solenoid should have a direct fluid path to the 1-2 shift spool valve. And forces the valve into a commanded 1st gear. This valve should be spring loaded, thus it defaults into 2nd, unless forced. Configuring the trans to have a first gear start could be as easy as removing a shuttle spring, and possibly swapping the side it sits on.

I also have a list of which trans had 1st gear start, and which had a 2nd gear start. Ill post it up if anyone is interested.

Yes shifting into 1st might cause some aggressive starts for the majority of us due to the fact that we are used to the standard 2nd gear start, and normally give these cars a bit more throttle to get moving.
To see what a standard 1st gear start would feel like, when stopped put the selector into B (1st), then back to D. It will start from 1st gear, and shift up normally to 2nd around 10-15km/h with normal acceleration input.

560 guys might not find this of any use, but 420 cars could help slightly with a 1st gear start, I manually do it quite frequently when driving around town in stop and go traffic.
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post #16 of 22 (permalink) Old 04-02-2018, 06:02 AM
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I have FGS module in my 91 560sec activated by the ES switch on the trans shift surround. Personally, I prefer the normal setting as the first gear start up shift is a little harsh especially if I nail it. When I nail it, it screeches the tires on upshift to second and I feel like a boy racer lol.
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post #17 of 22 (permalink) Old 04-03-2018, 01:44 PM
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I do the B1 thing on occasion and wish it held first gear a bit longer but it certainly works.
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post #18 of 22 (permalink) Old 04-03-2018, 04:21 PM
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Quote:
Originally Posted by corellian corvette View Post
I've spent the last hour searching the forums and broader internet and was unable to get an answer to this question. I've seen people ask, but never found the answer.

I'm aware it's possible to modify Gen1 cars to have permanent first gear start by jumping pins on a specific early TCM. Totally understand how that works.

But what I've been unable to find is how to modify a Gen2 car for permanent first gear start. I have an '87 420SEL that has the B switch which enables first gear start for that specific take-off.

However, I would like full-time FGS as is possible on the older cars. I can't find any instructions on how/if that's possible. There was some suggestions to try and manually move the switch but I'm averse to doing that unless someone can confirm this won't damage the transmission.

Can anyone confirm they have done this and have any suggestions on what to do?

Thanks!
https://www.benzworld.org/forums/r129...t-circuit.html
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post #19 of 22 (permalink) Old 04-04-2018, 01:55 AM
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If you read my thread "A Trek Up North", you can see exactly how and where I wired my FGS module and wired it up to a switch.

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1988 420 SEL Champagne/Brown



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post #20 of 22 (permalink) Old 04-05-2018, 02:57 PM Thread Starter
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@mclare thanks for the advice. I first ended up reading the SECOND "Trek Up North" thread which was quite a different story!

I poured through that thread - all 100 pages. Great read, but nowhere did I see how you actually wired it up. You make mention of how you modified the switch, and you could hear the relay click, but nothing about what you actually did.

Are you sure there isn't another thread?

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