Nissan GT-R Forum banner
1 - 20 of 20 Posts

·
Super Moderator
Joined
·
3,445 Posts
Discussion Starter · #3 ·
Thanks Vegas. Clutches hold power well and shift well 3-6 but 1st and 2nd gr behavior I just cant get to settle down at all.

1st feels like I'm letting out the clutch very slowly on a manual car and 2nd needs to build lot of revs before it moves forward.

Any ideas?
 

·
Registered
Joined
·
8,455 Posts
Thanks Vegas. Clutches hold power well and shift well 3-6 but 1st and 2nd gr behavior I just cant get to settle down at all.

1st feels like I'm letting out the clutch very slowly on a manual car and 2nd needs to build lot of revs before it moves forward.

Any ideas?
I was getting the same freaking thing.. 1-2 was not strong on the car.. Felt weak off the line ( major bog ) and 2nd felt like the clutches were slipping..

I guess For anything over 580whp or so.. It's not all that good from a dig .. Unless you have some boost off the line..
 

·
Super Moderator
Joined
·
3,445 Posts
Discussion Starter · #5 ·
Until the transmission warms up I really have to rec it a bit to get off from 1st. I have the Dodson race fluid which has more body but I may actually revert to the Willall V Spec transmission fluid. It is an ace product.
 

·
Super Moderator
Joined
·
3,445 Posts
Discussion Starter · #6 ·
I was getting the same freaking thing.. 1-2 was not strong on the car.. Felt weak off the line ( major bog ) and 2nd felt like the clutches were slipping..

I guess For anything over 580whp or so.. It's not all that good from a dig .. Unless you have some boost off the line..
I should add that my issue with first and second gear is from a dead stop and coming on the gas in 2nd at low speeds. Full throttle 1st and 2nd is fine. It's the part throttle thats killing me.
 

·
Registered
Joined
·
2,844 Posts
Until the transmission warms up I really have to rec it a bit to get off from 1st. I have the Dodson race fluid which has more body but I may actually revert to the Willall V Spec transmission fluid. It is an ace product.
Paprazzi, what you have done with the upgrades you have performed is change the calculated 'slip/stick' friction index of the transmission. This sounds like a funny term, but is something that the DSG (and clutched auto transmission) engineer spends much time on to ensure driveability. Very little is understood about this mode of transmission behaviour in the aftermarket - however understand that by changing the clutch friction type, the pre-load or clutch clearance, and then using a different type of fluid, that the hardware model of the transmission has changed drastically, but it still being managed with the original software model....if you get what I mean. Its not going to behave the same way....ever.

We spent some time on this mode of transmission behaviour some 18 months ago when specifying WR35TMVS. By changing the 'stiction index' of the base fluid the actual slip/stick behaviour of the transmission could be modified, and with tangible results. We were clearly able to change the 'transmission bucking' software behaviour one first gear take-off, and able to do so without decreasing high load clutch torque capacity. Now anyone in the business of selling DCT fluids should have a pretty good handle on the basic physics at play here and be able to match a fluid specification to the clutch behaviour to give near stock levels of driveability. Its not as simple as pour in the fluid and hope for the best, and it never has been. Whoever built your transmission should be able to very quickly and easily do this for you. If not, find someone that understands the process and work with them.

If need be - since you have been a great customer and supporter of ours over the years - we can happily blend you a special batch of fluid particularly for use in your vehicle that should calm the issues you are having down.
 

·
Registered
Joined
·
667 Posts
Smooth driving at all gears with new LC4 map especially starting from stanstill. Launch not faster than cobb LC2, I think too much 4500rpm launch for my car.
Unfortunately my 6th gear broken in my gearbox after each LC4 test high speed run.
I looking for parts of my transmission: need primary 2,4,6 cluster shaft, and 6th gear, all other seems fine.
 

·
Super Moderator
Joined
·
3,445 Posts
Paprazzi, what you have done with the upgrades you have performed is change the calculated 'slip/stick' friction index of the transmission. This sounds like a funny term, but is something that the DSG (and clutched auto transmission) engineer spends much time on to ensure driveability. Very little is understood about this mode of transmission behaviour in the aftermarket - however understand that by changing the clutch friction type, the pre-load or clutch clearance, and then using a different type of fluid, that the hardware model of the transmission has changed drastically, but it still being managed with the original software model....if you get what I mean. Its not going to behave the same way....ever.

We spent some time on this mode of transmission behaviour some 18 months ago when specifying WR35TMVS. By changing the 'stiction index' of the base fluid the actual slip/stick behaviour of the transmission could be modified, and with tangible results. We were clearly able to change the 'transmission bucking' software behaviour one first gear take-off, and able to do so without decreasing high load clutch torque capacity. Now anyone in the business of selling DCT fluids should have a pretty good handle on the basic physics at play here and be able to match a fluid specification to the clutch behaviour to give near stock levels of driveability. Its not as simple as pour in the fluid and hope for the best, and it never has been. Whoever built your transmission should be able to very quickly and easily do this for you. If not, find someone that understands the process and work with them.

If need be - since you have been a great customer and supporter of ours over the years - we can happily blend you a special batch of fluid particularly for use in your vehicle that should calm the issues you are having down.
Slip/stick is EXACTLY the terminology I would use! 1st feels like it slips too much then as the revs built it sticks too much.

I'm not qualified to talk in technical terms. But as someone who has driven the car on both fluids, I can say I prefer the "feel" ofWillall.

emailed you
 

·
CMD
Joined
·
1,130 Posts
How are your cars idling with LC4?

I am getting very uneven idle, especially when switching between P-R-D and when letting off the brakes to start off in first/reverse. All other gear shifts are seamless and smooth. Moving forward from a standstill is also smooth, but it's just that split second before your foot gets to the gas that the idle drops a bit.

Flashed back to LC2 tonight to do a gear relearn. LC2 was idling nice and smooth afterwards, but right after I flashed back to LC4, the jumping idle needle symptom came back.

I'm starting to wonder if LC4 VDC Off is NOT remembering the LC2 TCM gear relearn data after you do the uninstall/install?
 

·
Registered
Joined
·
479 Posts
How are your cars idling with LC4?

I am getting very uneven idle, especially when switching between P-R-D and when letting off the brakes to start off in first/reverse. All other gear shifts are seamless and smooth. Moving forward from a standstill is also smooth, but it's just that split second before your foot gets to the gas that the idle drops a bit.

Flashed back to LC2 tonight to do a gear relearn. LC2 was idling nice and smooth afterwards, but right after I flashed back to LC4, the jumping idle needle symptom came back.

I'm starting to wonder if LC4 VDC Off is NOT remembering the LC2 TCM gear relearn data after you do the uninstall/install?
No one should be assuming that doing a clutch learn or CC/TP setting with LC2 is the same thing as a clutch learn with LC4. Doing it on one flash and switching to another isn't a proper work around and isn't guarenteed to produce the same results. If you are getting any odd behviour or are just concerned about thigns not being right, you should stick with the correct map for your car untill the whole package is in place.

Eric
 

·
Premium Member
Joined
·
12,530 Posts
1st feels like I'm letting out the clutch very slowly on a manual car and 2nd needs to build lot of revs before it moves forward.
Any ideas?
What you are describing sounds more like slippage which requires you to apply a lot of throttle get the car moving. You mention it's worse when cold, but still sounds like an issue when warm. Is this an accurate assessment?

Assuming you've performed CGL, and that requested and actual Clutch A/B pressures are nominal, then you likely have a clutch assembly that isn't shimmed properly. This spacing is the most critical measurement that has a huge impact on how the clutches behave. Loosely packed clutches result in slippage.

How does the clutch behave with non-LC4 programming.
 

·
CMD
Joined
·
1,130 Posts
No one should be assuming that doing a clutch learn or CC/TP setting with LC2 is the same thing as a clutch learn with LC4. Doing it on one flash and switching to another isn't a proper work around and isn't guarenteed to produce the same results. If you are getting any odd behviour or are just concerned about thigns not being right, you should stick with the correct map for your car untill the whole package is in place.

Eric
I know that CC and TPs are transferred, I guess I assumed gear learns were as well. Not too much concern as the overall driveability is much improved. But, given the uneven idle is something that no one has discussed on here, I wanted to see if other folks were seeing the same.

Thanks for the feedback Eric, this helps to clarify things for sure.
 

·
Super Moderator
Joined
·
3,445 Posts
Discussion Starter · #14 ·
The shimming was not exact but was in the Dodson tolerances, additionally the spacing is now close to spec than it was on the stock clutches.

In any event is that what adjustability of touch points is meant to compensate for?
 

·
Registered
Joined
·
821 Posts
No one should be assuming that doing a clutch learn or CC/TP setting with LC2 is the same thing as a clutch learn with LC4. Doing it on one flash and switching to another isn't a proper work around and isn't guarenteed to produce the same results. If you are getting any odd behviour or are just concerned about thigns not being right, you should stick with the correct map for your car untill the whole package is in place.

Eric
I agree
 

·
Premium Member
Joined
·
12,530 Posts
The shimming was not exact but was in the Dodson tolerances, additionally the spacing is now close to spec than it was on the stock clutches.

In any event is that what adjustability of touch points is meant to compensate for?
Was the clutch learn performed and successful? What type of pressure are you seeing on the MFD at idle.
As far as the idle is concerned, it should be rock steady and not moving around at all. I've done 2200cc injectors on petrol with cams while still retaining a perfect idle. Here is an example:
 

·
Super Moderator
Joined
·
3,445 Posts
Discussion Starter · #17 ·
Was the clutch learn performed and successful? What type of pressure are you seeing on the MFD at idle.
As far as the idle is concerned, it should be rock steady and not moving around at all. I've done 2200cc injectors on petrol with cams while still retaining a perfect idle. Here is an example:
The clutch relearn using the cobb says it was performed sucessfully (it only took 30 secs or so) I asked Joe about it and he said the Cobb basically sets the relearn routine into motion, the TCM does the rest. So it appears for have been done sucessfully, but I got no clucnking and pressure increases during the relearn like I did in the past
 

·
Premium Member
Joined
·
12,530 Posts
I too have noticed that occasionally, the relearn process is very rapid without the usual noises and pressure spikes. Perhaps the Cobb only allows one CGL per x number of engine cycles or something along those lines.

Hope that helps.
 

·
Registered
Joined
·
479 Posts
The clutch relearn using the cobb says it was performed sucessfully (it only took 30 secs or so) I asked Joe about it and he said the Cobb basically sets the relearn routine into motion, the TCM does the rest. So it appears for have been done sucessfully, but I got no clucnking and pressure increases during the relearn like I did in the past
Again, the fact that you did a relearn on LC2 has no bearing on if that relearn is relevant to LC4.
 
1 - 20 of 20 Posts
Top