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Reverse takes a while...

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Member
1989560SL's picture
Johns Creek, GA
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Joined: December 3rd, 2007

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262

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1989 560SL
1990 300SE

I started noticing that it takes several seconds for reverse to engage on my 300SE. This problem just began on Saturday. I'll count 4-7 seconds of delay.

Any ideas would be greatly appreciated.

Thanks

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jtripp's picture
Babylon, NY
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1996 S420 LWB
1995 S350
Re: Reverse takes a while...

My experience has been that the Mercedes transmissions take a while longer to engage reverse than most cars. The reverse clutch plates are the largest diameter friction plates inside the transmission. It takes a larger volume of oil to compress the reverse clutch pack. As the frictions wear the reverse piston has to travel further to engage reverse. When the piston reaches the end of travel there will be no more friction material left on the plates and the car will slip in reverse. This has happened to me on 2 seperate 722.3 transmissions. The culprit was the inner reverse piston seal ruptured and dumped pressure allowing the frictions to wear out. The car was slipping in reverse backing into my driveway which is inclined uphill.

My advice is to just wait till you get positive reverse engagement. Your symptoms are normal.

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New York club member since 1976.

Continuous Mercedes ownership since 1964.

1993 300SD with '99 606 engine. 111,040 miles.
1994 S350   75,238 miles
1995 S350 148,124 miles.
1996 S420 with '99 606 engine  Sold
1999 S600  one of 14 imported  Sold 
1989 Bentley 8  Sold at 40,000 miles.

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Musky124cab's picture
Southbury, CT
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2012 ML350
1994 E320 Convertible
Re: Reverse takes a while...

My 94 Cab was doing the same thing then at 134,000 it would chatter so bad and slip. It got worse very quickly. I had the transmission rebuilt for $3,000 and now I don't have to be pointing down hill to go into reverse.

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1989560SL's picture
Johns Creek, GA
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1989 560SL
1990 300SE
Re: Reverse takes a while...

jtripp;171971 wrote:
My experience has been that the Mercedes transmissions take a while longer to engage reverse than most cars. The reverse clutch plates are the largest diameter friction plates inside the transmission. It takes a larger volume of oil to compress the reverse clutch pack. As the frictions wear the reverse piston has to travel further to engage reverse. When the piston reaches the end of travel there will be no more friction material left on the plates and the car will slip in reverse. This has happened to me on 2 seperate 722.3 transmissions. The culprit was the inner reverse piston seal ruptured and dumped pressure allowing the frictions to wear out. The car was slipping in reverse backing into my driveway which is inclined uphill.

My advice is to just wait till you get positive reverse engagement. Your symptoms are normal.

The delay is intermitent... sometimes it's normal (2-3 seconds)... other times it's longer (7-10 seconds). It seems to work better when cold.

Thanks

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rogo's picture
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Re: Reverse takes a while...

How many miles has it been since a fluid and filter change were done?

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Virginia Beach VA

87 300SDL
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Member
1989560SL's picture
Johns Creek, GA
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1990 300SE
Re: Reverse takes a while...

Robert Goodwin;172077 wrote:
How many miles has it been since a fluid and filter change were done?

I'm not sure exactly, since I've only owned it since December. I'll look through the records to see if the previous owner had it done recently.

Could this basic service make a difference?

Thanks

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Re: Reverse takes a while...

Transmission service is one of those commonly avoided expenses when contemplating a sale.

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Former Member
geezer's picture
Magee , MS
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1972 280SE
Re: Reverse takes a while...

I would service the trans with a filter change. A lot of the time it's the filter doing its job and it's time to change.

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Lawrenceville, GA
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1970 280SL
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Re: Reverse takes a while...

Under regular duty, these transmissions are supposed to be serviced every 30k miles. This includes filter and fluid, plus draining the torque converter.

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pch2021's picture
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Re: Reverse takes a while...

On a 300se, this really isn't normal, per se, but I would start by servicing the gearbox. Blockage in the filter helps the delay. These don't use a convenional piston like the old 722.1 did. Rather, these clutches wear individually of the ones in the rest of the box. I have replaced only the reverse clutches on several of these.

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Pierre Hedary
...happily servicing vintage Mercedes-Benz in sunny Florida...
1972 280SE 4.5 252K
1970 280se 3.5 coupe 108K
1971 300sel 4.5 121K
1991 420SEL TMU, but looks brand new!
Mercedes technical advice: 407 765 2867

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1989560SL's picture
Johns Creek, GA
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1989 560SL
1990 300SE
Re: Reverse takes a while...

pch2021;172105 wrote:
On a 300se, this really isn't normal, per se, but I would start by servicing the gearbox. Blockage in the filter helps the delay. These don't use a convenional piston like the old 722.1 did. Rather, these clutches wear individually of the ones in the rest of the box. I have replaced only the reverse clutches on several of these.

Pierre,

Are you stating that a fluid and filter change will, or will not help? My tech seems to think that it needs the rear clutch to be replaced. The miles are relatively low, so he doesn't think it needs a complete rebuild.

Thanks

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Re: Reverse takes a while...

Not to cast despersions upon your mechanic but, this is how your transmission works. I am unable to reconcile his comment with the K-2 clutch interaction with first and fourth gears.

TRANSMISSION
Transmissions are fully automatic 4 or 5-speed consisting of
a 3-element welded torque converter, 2 or 3 compound planetary gear
sets, 2 or 3 multiple-disc clutches, one overrunning clutch and 3
brake bands. See Figs. 1 and 2. Brake bands control function of
planetary gear sets. A hydraulic system, pressurized by a primary gear
type pump and a secondary piston type pump provide working pressure
required to operate friction elements and automatic controls.
1st Gear
In 1st gear, brake band B-2 is applied and one-way converter
clutch is locked. In selector lever position "2", clutch K-2 is also
engaged. Both planetary gear sets are involved in gear reduction.
2nd Gear
In 2nd gear, brake band B-1 and brake band B-2 are applied.
Both planetary gear sets are involved in gear reduction.
3rd Gear
In 3rd gear, brake band B-2 is applied and clutch K-1 is
engaged. Only rear planetary gear set is involved in gear reduction.
4th Gear
In 4th gear, clutch K-1 and clutch K-2 are applied. Both
planetary gear sets rotate as a locked unit.
5th Gear
On 722.5 Series models, clutch K-1, clutch K-2 and overdrive
brake are applied in 5th gear. Overdrive clutch and 2nd one-way clutch
are also applied in all forward gears.
Reverse Gear
In reverse, brake B-3 is applied, one-way converter clutch is
locked, and clutch K-2 is engaged. Both planetary gear sets are
involved in gear reduction.

Did you leave out some pertinent information on performance in the forward gears?

You can certainly proceed any way you wish, howver, the suggestion to change the fluid and filter are based on the possibility that that may be all that is wrong with it. Therefore, it would seem prudent to spend a little money to find out before you spend hundreds or thousands to repair a transmission that may not need repairing.

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1989560SL's picture
Johns Creek, GA
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1989 560SL
1990 300SE
Re: Reverse takes a while...

Robert Goodwin;172134 wrote:
Not to cast despersions upon your mechanic but, this is how your transmission works. I am unable to reconcile his comment with the K-2 clutch interaction with first and fourth gears.

TRANSMISSION
Transmissions are fully automatic 4 or 5-speed consisting of
a 3-element welded torque converter, 2 or 3 compound planetary gear
sets, 2 or 3 multiple-disc clutches, one overrunning clutch and 3
brake bands. See Figs. 1 and 2. Brake bands control function of
planetary gear sets. A hydraulic system, pressurized by a primary gear
type pump and a secondary piston type pump provide working pressure
required to operate friction elements and automatic controls.
1st Gear
In 1st gear, brake band B-2 is applied and one-way converter
clutch is locked. In selector lever position "2", clutch K-2 is also
engaged. Both planetary gear sets are involved in gear reduction.
2nd Gear
In 2nd gear, brake band B-1 and brake band B-2 are applied.
Both planetary gear sets are involved in gear reduction.
3rd Gear
In 3rd gear, brake band B-2 is applied and clutch K-1 is
engaged. Only rear planetary gear set is involved in gear reduction.
4th Gear
In 4th gear, clutch K-1 and clutch K-2 are applied. Both
planetary gear sets rotate as a locked unit.
5th Gear
On 722.5 Series models, clutch K-1, clutch K-2 and overdrive
brake are applied in 5th gear. Overdrive clutch and 2nd one-way clutch
are also applied in all forward gears.
Reverse Gear
In reverse, brake B-3 is applied, one-way converter clutch is
locked, and clutch K-2 is engaged. Both planetary gear sets are
involved in gear reduction.

Did you leave out some pertinent information on performance in the forward gears?

You can certainly proceed any way you wish, howver, the suggestion to change the fluid and filter are based on the possibility that that may be all that is wrong with it. Therefore, it would seem prudent to spend a little money to find out before you spend hundreds or thousands to repair a transmission that may not need repairing.

Forward gears work perfectly fine, engaging quickly and shifting smoothly.

I've decided to do a fluid and filter change first. Hopefully it solves the problem.

Thanks

Member
1989560SL's picture
Johns Creek, GA
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1989 560SL
1990 300SE
Re: Reverse takes a while...

Well, she stopped going into reverse on Friday night. Only inop when she's hot. She shifts right into reverse when cold.

I've got her in the shop, and I pray for the best.

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Re: Reverse takes a while...

That trans is the same as the one as the one in my 92, (722.3) I had the same issue, drained it, filled it at dealer. They found nothing in the pan, 3 months later, fine cold, shuttering worse in reverse when hot. I took it back to dealer something about "front clutch" they replacec it with a MB reman 2 year warranty, $4k. They dont rebuild anymore, some local shops half the price offer 90 day warranty, the price included new cooler lines and trans mount.

nhdoc (not verified)
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nhdoc's picture
Re: Reverse takes a while...

99% of the time a dealer will recommend replacement of a transmission for a problem like this...it's a shame because most of the time they can be fixed for much less than the cost of replacement. If your place sends you down the "replacement for $4K route" I would call around to some local shops who specialize in transmission work and describe the problem to them and see if they are willing to repair it rather than replace it. Anyone can replace it. It takes skill, knowledge and honesty to repair it - something that few shops have today.

Common cause is worn B3 reverse clutch:

http://www.peachparts.com/shopforum/showthread.php?t=99048&highlight=reverse+722.3

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Re: Reverse takes a while...

I'll second that the older transmissions can be properly rebuilt by someone with the knowledge and the experience.

Marc, isn't MBCA member Mat Cama in Georgia -- hopefully not far from you? I am going to guess he can rebuild that transmission for you.

But then again, IIRC you work for a Mercedes dealer so your employee discount, if any, might make a factory transmission the better route.

Good luck, and let us know how you do.

Regards,

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