RP Synchromax made it WORSE?

e86nut · 03-26-2023, 05:22 PM

Recently swapped out the stock trans fluid for RP Synchromax to see if it would help with the 1->2 shift. This happened at the same time the car got headers and re tuned, with the power going up from 305WHP to 335WHP.

I've taken the car on several spirited drives and it seems to have made things worse. 1->2 shift is still pretty much the same but now 3->4 is awful. I missed that shift like 3 times under full load, it was just painful. I basically have a solid grip and apply constant force and then the car shifts. When I'm super deliberate about it, it seems fine but it requires way more force than before.

Not sure if this is related to the tune/power bump (i don't think so). I'm guessing the best thing to do is try another trans fluid or go back to stock?

3002 tii · 03-26-2023, 07:14 PM

Doubt its tune/power. Some folks swear by RP but one thing I've never heard is someone complain about the OEM stuff (i.e., MTF-LT2). Try OE fluid and see how that works out.

wdb · 03-26-2023, 08:16 PM

I used RP and it was better than the Redline stuff the PO had in there. Still not a slam shift gearbox. Never will be IMO.

XMetal · 03-26-2023, 08:42 PM

I have RP in mine and still does. It's much better shifting than the OE fluid for me.

e86nut · 03-26-2023, 10:29 PM

Quote:

Originally Posted by XMetal

I have RP in mine and still does. It's much better shifting than the OE fluid for me.

Do you have trouble with 3-4 shift?

e86nut · 03-26-2023, 11:19 PM

Quote:

Originally Posted by 3002 tii

Doubt its tune/power. Some folks swear by RP but one thing I've never heard is someone complain about the OEM stuff (i.e., MTF-LT2). Try OE fluid and see how that works out.

Was looking at FCP and it seems theres LT-2 and LT-3? Is it LT_2 across the board for all Z4Ms?

XMetal · 03-26-2023, 11:35 PM

Quote:

Originally Posted by e86nut

Do you have trouble with 3-4 shift?

Nope. My main reason for switching from OE was the 1-2 shift and RP definitely made that better. 3-4 shift was never an issue for me whether OE or RP.

wdb · 03-27-2023, 05:39 AM

Quote:

Originally Posted by XMetal

Nope. My main reason for switching from OE was the 1-2 shift and RP definitely made that better. 3-4 shift was never an issue for me whether OE or RP.

Ditto. 1-2 and 3-2; well, pretty much anything-2.

3002 tii · 03-27-2023, 07:51 AM

Quote:

Originally Posted by wdb

Ditto. 1-2 and 3-2; well, pretty much anything-2.

Weird. I swear other than the first few weeks of owning a Z where I was getting used to it, I’ve never had issues with 2nd gear in all 3 Zs I’ve owned. Granted they weren’t entirely stock (e.g. some has CDV delete, others had a ssk) but those really wouldn’t that make of an impact. I just let the clutch out a little slower for 2nd and it’s good.

wdb · 03-27-2023, 08:08 AM

Quote:

Originally Posted by 3002 tii

Weird. I swear other than the first few weeks of owning a Z where I was getting used to it, I’ve never had issues with 2nd gear in all 3 Zs I’ve owned. Granted they weren’t entirely stock (e.g. some has CDV delete, others had a ssk) but those really wouldn’t that make of an impact. I just let the clutch out a little slower for 2nd and it’s good.

What I find really weird is that the gearbox in the M is the same as in the non-M, and I never had any problems in my 3.0si coupe. It's just the M cars that seem to cause people to grumble about shifting issues.

grannyknot · 03-27-2023, 08:29 AM

Quote:

Originally Posted by wdb

What I find really weird is that the gearbox in the M is the same as in the non-M, and I never had any problems in my 3.0si coupe. It's just the M cars that seem to cause people to grumble about shifting issues.

Yeah, because it's an ///M so drivers start jamming gears like it was an old muscle car.

To the OP, these transmissions need a little more finesse when driving fast, you can't jam gears no matter what fluid you are running.

e86nut · 03-27-2023, 09:58 AM

Quote:

Originally Posted by grannyknot

Yeah, because it's an ///M so drivers start jamming gears like it was an old muscle car.

To the OP, these transmissions need a little more finesse when driving fast, you can't jam gears no matter what fluid you are running.

Quote:

Originally Posted by 3002 tii

Weird. I swear other than the first few weeks of owning a Z where I was getting used to it, I’ve never had issues with 2nd gear in all 3 Zs I’ve owned. Granted they weren’t entirely stock (e.g. some has CDV delete, others had a ssk) but those really wouldn’t that make of an impact. I just let the clutch out a little slower for 2nd and it’s good.

I'm never specifically trying to jam gears but just shift quickly when I'm full throttle - When you are full throttle, what exactly should my shifting technique be for a smooth shift?

grannyknot · 03-27-2023, 11:31 AM

Quote:

Originally Posted by e86nut

I'm never specifically trying to jam gears but just shift quickly when I'm full throttle - When you are full throttle, what exactly should my shifting technique be for a smooth shift?

You gotta remember you are driving a car designed for the street. Z4M's are a fun car on the track but they are not race cars.
Shifting gears quickly at full throttle is a situation you'll never encounter on the street, at least not if you are driving within the law.

It sounds like you are pushing it to its street car limits but expecting race car capabilities.
You could also have damaged synchros and that is making shifting worse, driving it to it's limits will continue to degrade those synchos. I doubt this is a problem that is going to be solved by trans fluid alone.

I think you might have to slow your shifting down a bit, a very slight pause in neutral before going to the next gear.
You could also go old school and double clutch.

maupineda · 03-27-2023, 11:43 AM

The issue would be less present on the Si as the powertrain assembly rotates slower, so the synchros maybe at the limit of what they can handle when shifting at redline and trying to be fast. The ///M has 1000 rpm more, and that effect is multiplied by the gear ratios. So the 1/2 synchro spins about 4000 rpm more compared to what the tranny sees in the Si variant.

3002 tii · 03-27-2023, 08:57 PM

Quote:

Originally Posted by e86nut

I'm never specifically trying to jam gears but just shift quickly when I'm full throttle - When you are full throttle, what exactly should my shifting technique be for a smooth shift?

Quote:

Originally Posted by grannyknot

You gotta remember you are driving a car designed for the street. Z4M's are a fun car on the track but they are not race cars.
Shifting gears quickly at full throttle is a situation you'll never encounter on the street, at least not if you are driving within the law.

It sounds like you are pushing it to its street car limits but expecting race car capabilities.
You could also have damaged synchros and that is making shifting worse, driving it to it's limits will continue to degrade those synchos. I doubt this is a problem that is going to be solved by trans fluid alone.

I think you might have to slow your shifting down a bit, a very slight pause in neutral before going to the next gear.
You could also go old school and double clutch.

+WHS, I only make a conscious effort to shift fast when I'm on track and it's mostly 4th and 5th. On the street, I don't race from a dig (or street race in general) so I've never found the need to shift "fast". But I quickly learned, the best way for 1st to 2nd was rev higher and let the clutch out slower and shift normally. It's butter smooth each time. This in contrast to when I bought my first Z in '08 and I was trying to pound the gears and would get the dreaded 1st to 2nd crunch...

e86nut · 03-29-2023, 02:59 PM

Quote:

Originally Posted by 3002 tii

+WHS, I only make a conscious effort to shift fast when I'm on track and it's mostly 4th and 5th. On the street, I don't race from a dig (or street race in general) so I've never found the need to shift "fast". But I quickly learned, the best way for 1st to 2nd was rev higher and let the clutch out slower and shift normally. It's butter smooth each time. This in contrast to when I bought my first Z in '08 and I was trying to pound the gears and would get the dreaded 1st to 2nd crunch...

Ok so I took the car out today and made a conscious effort to shift a bit more relaxed and it was absolutely fine. So moral of the story is I need to learn how to drive the car better and not carry over my other experiences with manual cars. I'm still gonna go back to OEM LT-2 fluid and see if it helps. I guess I'm not winning any drag races but who cares!

wyshyvanuk · 03-29-2023, 03:19 PM

Very interested in the LT-2 comparison. Thanks!

3002 tii · 03-29-2023, 06:13 PM

Quote:

Originally Posted by e86nut

Ok so I took the car out today and made a conscious effort to shift a bit more relaxed and it was absolutely fine. So moral of the story is I need to learn how to drive the car better and not carry over my other experiences with manual cars. I'm still gonna go back to OEM LT-2 fluid and see if it helps. I guess I'm not winning any drag races but who cares!

That or buy my 4.10s for sale and just always start in 2nd gear lol

maupineda · 03-29-2023, 06:55 PM

Quote:

Originally Posted by 3002 tii

That or buy my 4.10s for sale and just always start in 2nd gear lol

How much are you asking for the 4.1, would it be a swap of the whole pumpkin, or you will remove the crown and pinion from yours firt?

86Zed · 03-30-2023, 08:48 AM

Similar experiences to others. I run Redline fluids (MT, diff) and ZHP knob, shift purposely but not in a rapid-fire way and no real issues. On very cold days it can be tougher until the fluids warm up.

Even on track in my M and other cars I am never frantic. Purposeful and swift, more important to get the shift and revs right than shave that .01s.

Finnegan · 04-17-2023, 09:19 PM

Quote:

Originally Posted by e86nut

Recently swapped out the stock trans fluid for RP Synchromax to see if it would help with the 1->2 shift. This happened at the same time the car got headers and re tuned, with the power going up from 305WHP to 335WHP.

I've taken the car on several spirited drives and it seems to have made things worse. 1->2 shift is still pretty much the same but now 3->4 is awful. I missed that shift like 3 times under full load, it was just painful. I basically have a solid grip and apply constant force and then the car shifts. When I'm super deliberate about it, it seems fine but it requires way more force than before.

Not sure if this is related to the tune/power bump (i don't think so). I'm guessing the best thing to do is try another trans fluid or go back to stock?

How many years or miles on your motor and transmission mounts? I would look at that before I looked at fluid. All the other comments hit every other thought I might have. There’s a thread sticky on the topic of mounts in the engine and drivetrain sub forum.

miscbrah · 04-17-2023, 10:04 PM

My first z never had the 1-2 crunch, sold it w/ over 90k miles. Ran OEM fluid.

Current z does grind on the 1-2 shift from time to time, 32k miles on her, going to fill with fresh OEM and see if that changes anything.

I did run redline diff fluid FWIW, read too much conflicting info on the use of other tranny fluids to switch from OEM.

03-26-2023, 05:22 PM	#1
e86nut Private 22 Rep 59 Posts Drives: 2007 BMW Z4 M Coupe Join Date: Nov 2022 Location: Seattle iTrader: (0)	RP Synchromax made it WORSE? Recently swapped out the stock trans fluid for RP Synchromax to see if it would help with the 1->2 shift. This happened at the same time the car got headers and re tuned, with the power going up from 305WHP to 335WHP. I've taken the car on several spirited drives and it seems to have made things worse. 1->2 shift is still pretty much the same but now 3->4 is awful. I missed that shift like 3 times under full load, it was just painful. I basically have a solid grip and apply constant force and then the car shifts. When I'm super deliberate about it, it seems fine but it requires way more force than before. Not sure if this is related to the tune/power bump (i don't think so). I'm guessing the best thing to do is try another trans fluid or go back to stock?
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03-26-2023, 07:14 PM	#2
3002 tii Lieutenant General 2280 Rep 12,565 Posts Drives: Z4 M, X5, GX460 Join Date: Apr 2008 Location: CT iTrader: (99) Garage List F15 X5 xDrive35i [8.75] E86 Z4 M [10.00] F10 550i (Retired) [9.17] F25 X3 xDrive35i (R ... [9.43] E82 135is (Retired) [9.50] E85 Z4 M (Retired) [9.41] E90 328i xDrive (Re ... [9.25] E86 Z4 3.0si (Retired) [9.20]	Doubt its tune/power. Some folks swear by RP but one thing I've never heard is someone complain about the OEM stuff (i.e., MTF-LT2). Try OE fluid and see how that works out. __________________ Follow for latest mods
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03-26-2023, 08:16 PM	#3
wdb dances with roads 4718 Rep 4,094 Posts Drives: '07 E86, '02 996, '95 Seven Join Date: Jul 2015 Location: the perimeter iTrader: (4)	I used RP and it was better than the Redline stuff the PO had in there. Still not a slam shift gearbox. Never will be IMO.
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03-26-2023, 08:42 PM	#4
XMetal Colonel 1130 Rep 2,864 Posts Drives: Anything Join Date: Apr 2010 Location: SoCal iTrader: (0) Garage List 2008 Z4M Coupe [10.00] 2018 Audi S3 [0.00] 2004 X5 [8.50]	I have RP in mine and still does. It's much better shifting than the OE fluid for me. __________________
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03-27-2023, 11:43 AM	#14
maupineda Captain 456 Rep 973 Posts Drives: E86 Z4MC Join Date: Jul 2012 Location: Detroit, MI iTrader: (3)	The issue would be less present on the Si as the powertrain assembly rotates slower, so the synchros maybe at the limit of what they can handle when shifting at redline and trying to be fast. The ///M has 1000 rpm more, and that effect is multiplied by the gear ratios. So the 1/2 synchro spins about 4000 rpm more compared to what the tranny sees in the Si variant.
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03-29-2023, 03:19 PM	#17
wyshyvanuk Second Lieutenant 449 Rep 229 Posts Drives: 2008 Z4 MR Join Date: Apr 2018 Location: Tucson AZ iTrader: (0)	Very interested in the LT-2 comparison. Thanks!
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03-30-2023, 08:48 AM	#20
86Zed Get off my lawn 932 Rep 1,158 Posts Drives: 6MT Join Date: Sep 2015 Location: USA iTrader: (7) Garage List 2023 GR Corolla [0.00] 2022 BMW X3 M40i [10.00] 2007 BMW Z4M Coupe [0.00] 2002 BMW 325xiT [0.00] 1991 BMW 318is [0.00]	Similar experiences to others. I run Redline fluids (MT, diff) and ZHP knob, shift purposely but not in a rapid-fire way and no real issues. On very cold days it can be tougher until the fluids warm up. Even on track in my M and other cars I am never frantic. Purposeful and swift, more important to get the shift and revs right than shave that .01s.
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04-17-2023, 10:04 PM	#22
miscbrah Private 11 Rep 66 Posts Drives: Z4 3.0si Join Date: Sep 2016 Location: Boston iTrader: (0)	My first z never had the 1-2 crunch, sold it w/ over 90k miles. Ran OEM fluid. Current z does grind on the 1-2 shift from time to time, 32k miles on her, going to fill with fresh OEM and see if that changes anything. I did run redline diff fluid FWIW, read too much conflicting info on the use of other tranny fluids to switch from OEM.
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