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Discussion Starter · #1 ·
Hello, 10 months ago i had a gearbox rebuild by a gtr workshop from czech after 1-r shift fork failure on a 2009 cba model. They replaced clutches with 7 plate packs, a and b clutch baskets with billett ones and a billett 1-r shift fork along with allwd rebuild, syncros change and circlip upgrade. Since rebuild i did aprox. 2kkm. The car behaved strangly after rebuild, it was like sttutering when take off on incline. Same thing happend on lc4 or lc5. The builder said i should rid the cobb and use ecuTek software?? A month ago or before 200km the car started to almost stall if the odd gear correction wasnt on -3 or -4. It did the gear relearn no problem every time. Yesterday the car threw the p284b code when i started the engine on driveway. I drained the oil today, it was clean, intake filter also but dodson main filter was coated with black debris. Also 1-r sift fork was aproxx 2mm out of position. I positioned the fork and cleaned the filters. Tomorrow ll be filling back with new oil. Oil was pentosin ffl-4. Any idea what could be the issue.
Thank you for any help
 

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Did you update the gear selection rings since the CBA ones have been known to break their teeth? When you say "odd gear correction" at -3 to -4 should I assume you are referring to the touch points? If so this might indicate an issue with the working clearances on the clutches, but I would assume the builder set those up correctly. Might want to consider posting a log so we can see what's happening. ECUTek is going to give you features not available with Cobb, but I don't think that will have any bearing on your issues. The stuttering sounds like clutch chatter, which may or may not tune out with the clutch torque table and is a common unreported problem with aftermarket clutches.
 

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Discussion Starter · #3 ·
Did you update the gear selection rings since the CBA ones have been known to break their teeth? When you say "odd gear correction" at -3 to -4 should I assume you are referring to the touch points? If so this might indicate an issue with the working clearances on the clutches, but I would assume the builder set those up correctly. Might want to consider posting a log so we can see what's happening. ECUTek is going to give you features not available with Cobb, but I don't think that will have any bearing on your issues. The stuttering sounds like clutch chatter, which may or may not tune out with the clutch torque table and is a common unreported problem with aftermarket clutches.
Yes the selection rings were changed aswell, yesterday i took off the valve body and fork was stuck aprox 3mm out off centre. I pushed ti gently with small pry bar and it centered it self with ease. I cleaned the filters, valve body and assembled all back and it works ok now. Also dodson filter was full of muck after 2kkm, i am so sorry that i didnt make the works myself.
This are the gearbox settings 0-0-0-(-4)



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You should be able to operate the clutch fork by hand without a pry bar and with all of that sludge on the filter it may be a good idea to pull apart the valve body and clean it. The -4 is your touch point so this is just the preload pressure on the clutches bringing them closer together (+TP's) or further apart (-TP's). I found that running negative TP's when trying to resolve 1st gear clutch chatter would cause the clutches to slip. I would advise that you log your clutch slip to make sure that is not happening. BTW, are those particles on the filter attracted to a magnet?
 

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Discussion Starter · #5 ·
You should be able to operate the clutch fork by hand without a pry bar and with all of that sludge on the filter it may be a good idea to pull apart the valve body and clean it. The -4 is your touch point so this is just the preload pressure on the clutches bringing them closer together (+TP's) or further apart (-TP's). I found that running negative TP's when trying to resolve 1st gear clutch chatter would cause the clutches to slip. I would advise that you log your clutch slip to make sure that is not happening. BTW, are those particles on the filter attracted to a magnet?
No, not by magnet, we have a yacht service and particles are the same as clutch particles on boat hydraulic gearbox. Now the fork moves freely with hand

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No, not by magnet, we have a yacht service and particles are the same as clutch particles on boat hydraulic gearbox. Now the fork moves freely with hand
That's why I asked because I suspect that running a -4 TP is causing excessive clutch slip
 

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Discussion Starter · #7 ·
That's why I asked because I suspect that running a -4 TP is causing excessive clutch slip
First issue was that no matter what i do the car would i dont know how exactly to explain but stutter on take of, it was happening for approx 1.8kkm and after that i did a gear relearn and after that the car would pull forward hard on idle if touch point for odd gear were set to 0. If on -4 or even better on -5 the car would take off normaly. I suspect the clutch clearances were not set up correctly.

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First issue was that no matter what i do the car would i dont know how exactly to explain but stutter on take of, it was happening for approx 1.8kkm and after that i did a gear relearn and after that the car would pull forward hard on idle if touch point for odd gear were set to 0. If on -4 or even better on -5 the car would take off normaly. I suspect the clutch clearances were not set up correctly.
The clutch chatter is not uncommon from what I have found and I have it as well with the Linney 8 plate clutch. Also, even though you put in higher capacity clutches, you still likely need to increase the clutch torque (basket pressures) or it can actually slip using the factory settings, which was the case with the Linney Clutches. They will ultimately hold more torque vs stock clutches, but require more clutch pressures to do it.

If the working clearance was setup properly you should not have a hard lurch forward with Touch Points set to zero after a relearn. If you are forced to set Touch Points to -5 then you likely need to modify the Clutch Torque table to increase basket pressures to eliminate clutch slip. If you are not logging these things then you have no idea what its doing, but you know its slipping because your line filter is full of clutch debris.
 

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Discussion Starter · #9 ·
The clutch chatter is not uncommon from what I have found and I have it as well with the Linney 8 plate clutch. Also, even though you put in higher capacity clutches, you still likely need to increase the clutch torque (basket pressures) or it can actually slip using the factory settings, which was the case with the Linney Clutches. They will ultimately hold more torque vs stock clutches, but require more clutch pressures to do it.

If the working clearance was setup properly you should not have a hard lurch forward with Touch Points set to zero after a relearn. If you are forced to set Touch Points to -5 then you likely need to modify the Clutch Torque table to increase basket pressures to eliminate clutch slip. If you are not logging these things then you have no idea what its doing, but you know its slipping because your line filter is full of clutch debris.
Can i log clutch slip with cobb ap?

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Can i log clutch slip with cobb ap?
If you have a V3 AccessPort you can log Clutch Slip (A&B), Line Pressure, Clutch Pressure Target (A&B), Clutch Torque, RPM, Theoretical Pulsewidth, Gear
 

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Sorry to revive this thread but... What causes Shift Forks to chip or break?? I've already chipped my 1/R and broke 2/4.. replaced with Dodson. but why do they break??
 
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