Brake snip issue

[Terry@BMS]

Could be nothing, could be a worn ujoint somewhere, or maybe a broken trans mount? You'll have to better diagnose where the noise is coming from.

There is going to be a physical limit on the strength of parts somewhere. In terms of the trans and transfer case for AWD cars, I have absolutely no idea where that limit is. Push your cars accordingly.

 

[Tonkabob]

I do also like the broken hardware idea but here is my bing on T Converters issues:
"Symptoms of a bad torque converter include overheating, slipping, shuddering, dirty fluid, high stall speeds, or strange noises. On most occasions, the torque converter will not be the cause of the problem so don't rush to any conclusions until you get your transmission checked out first."
The 3500 stall on his car now is a red flag as most are hitting 2800-3000 on the brake mod. Will it hit 3500 faster now or still takes 5 seconds?

 

[brancky3]

I do also like the broken hardware idea but here is my bing on T Converters issues:
"Symptoms of a bad torque converter include overheating, slipping, shuddering, dirty fluid, high stall speeds, or strange noises. On most occasions, the torque converter will not be the cause of the problem so don't rush to any conclusions until you get your transmission checked out first."
The 3500 stall on his car now is a red falg as most are hitting 2800-3000 on the brake mod. Will it hit 3500 faster now or still takes 5 seconds?

So you're telling me if we break our torque converters we can launch higher?? HELLO 10's!

 

[Terry@BMS]

With a torque converter failure (I've blown plenty over my 20 years of racing) normally the car just won't go or takes a lot more gas than it should to get going.

A clunk when shifting to drive or reverse is normally a worn or damaged ujoint or broken/loose trans or differential mount.

 

[KLR STINGER]

With a torque converter failure (I've blown plenty over my 20 years of racing) normally the car just won't go or takes a lot more gas than it should to get going.

A clunk when shifting to drive or reverse is normally a worn or damaged ujoint or broken/loose trans or differential mount.

Was going to say the same thing. Clunking on shifts sounds like driveline slop not a bad TC

 

[Christopher Léger]

5 seconds and 3500 rpm is alot if strain and heat on the torque converter desingened to handle 2200 rpm and 4 seconds. Sounds like its damaged to me. Most people are holding less than a second on the brake snip.
@Terry@BMS thoughts?

I didnt count the secondes but i did not hold the 3500 except the 2nd time for 1 sec... the reason im sayong i holding it is that it dont shoot straight up to 3000+ on the initial kick felt like it went up in stages

 

[Revvdmedia]

I agree with either U-joint(s) or trans mounts. Brake boosting is loading rotational force against the output shaft on the transmission/differential which is being held by the brakes. Think of it like putting too much torque on a small bolt, if you over-torque it, the head breaks off. It is possible something gave in, even just a little bit, and there is now slop. Guys who are doing the brake snip are seeing 8+ PSI prior to launch from what I have seen, that is a healthy amount of rotational torque being held against its will by the brakes.

This is similar to why guys break axles running slicks in Mustangs. On stock wheels, you can't full apply all the full rotational torque off a launch because the tires slip before the axles see maximum torque, limiting the axles from seeing a full "400lb/ft+." Put on drag slicks, now if you can put even more power down, closer to full torque, the rotational twisting force is higher and snaps axles in half.

If the case of a U-joint, it is the "pin" between the output shaft and axle coupling, it can only handle so much torque being twisted against it.

 

[SteveCo]

Get it up on a lift, Christopher, and check the driveline from the transmission back to the wheels, including the joints, to see if you can identify something loose or broken.

Somebody on here already experienced a failure of one of their driveline joints through apparently normal driving, though it's unclear exactly where the point of failure was or what was the actual cause. Maybe there is a weak link starting to show up, and fixing yours could be a relatively simple, inexpensive fix ...

 

[Christopher Léger]

Get it up on a lift, Christopher, and check the driveline from the transmission back to the wheels, including the joints, to see if you can identify something loose or broken.
Somebody on here already experienced a failure of one of their driveline joints through apparently normal driving, though it's unclear exactly where the point of failure was or what was the actual cause. Maybe there is a weak link starting to show up, and fixing yours could be a relatively simple, inexpensive fix ...

Alrighy ill see within next days what the dealership responds with TC waranty... he did say the drive axles had a bit of a loose in it thus him saying its like it nudges on something in TC... i will put all your inputs as hypothesis next time i go in.. ujoints and trans mount

 

[Kazz]

No freaking way in hell I'm hacking on wires at my ECU boys and girls. No turning back from trashed warranty after that.

 

[SVStinger]

Alrighy ill see within next days what the dealership responds with TC waranty... he did say the drive axles had a bit of a loose in it thus him saying its like it nudges on something in TC... i will put all your inputs as hypothesis next time i go in.. ujoints and trans mount

Just for my edification. Are you seeing this noise or clunk or what have you when you shift into the gear when you have the switch thrown to shut off the brake signal to the ECU? Or does this happen when you have the brake signal to the ECU turned on? Or Both?

 

[Tonkabob]

No freaking way in hell I'm hacking on wires at my ECU boys and girls. No turning back from trashed warranty after that.

Looks like you are one of he few sane ones. Has to be a dozen snipers out their already. I'm waiting on initial test results and then will decide.

 

[Adamdan]

Looks like you are one of he few sane ones. Has to be a dozen snipers out their already. I'm waiting on initial test results and then will decide.

Me too and waiting to see if there’s a better way to do it. I don’t think I could cut a wire to the ecu, there’s no going back. Maybe something plug and play. Lap 3 said they will have brake boosting optional in there ecu tune with no cutting of any wires.

 

[Kamauxx]

Me too and waiting to see if there’s a better way to do it. I don’t think I could cut a wire to the ecu, there’s no going back. Maybe something plug and play. Lap 3 said they will have brake boosting optional in there ecu tune with no cutting of any wires.

I haven't seen a real Lap3 ECU update since last year. Have they announced more info some where?

 

[Adamdan]

I haven't seen a real Lap3 ECU update since last year. Have they announced more info some where?

I made a comment on there YouTube video they release and he replied saying something like when ecu Encryption solution is ready we will release ecu tunes with brake boostings as a option. He also said they have been using brake boosting in the past Hyundai and Kia tunes.

 

[Tonkabob]

Me too and waiting to see if there’s a better way to do it. I don’t think I could cut a wire to the ecu, there’s no going back. Maybe something plug and play. Lap 3 said they will have brake boosting optional in there ecu tune with no cutting of any wires.

Very interesting on the lap3 ecu tune. Just saw on fb the green black wire in the cabin fuse box might be the same wire. If so easier tap and easier to hide.
Test anyone?

 

[Christopher Léger]

Just for my edification. Are you seeing this noise or clunk or what have you when you shift into the gear when you have the switch thrown to shut off the brake signal to the ECU? Or does this happen when you have the brake signal to the ECU turned on? Or Both?

Both.. mecanic told me a comparison luke when mustang get too powerfull and engaging a gear makes the wheels wanna spin..

So both flipped on/off map 0-2 its permanent..

 

[Ty Davis]

I just did the brake snip and seems to work i could get it to 3500 rpm... i did not luanch it but just tested it...

I now have an issue where when i put it on D it feels like the tranny is giving the car a jerk on start off even without fuel.. i tried putting R, then N and D and still giving me a jerk... i will see if it does it every time i leave a stop or red light, and also on R... but im a little concerned about it

I am not sure what you are feeling is a mechanical fault.
Could very well be an electronic gremlin left over from your experiment.

Reset the ECU/TCU and tell me if it goes away.
To reset, (with car off) remove the Negative battery terminal in the trunk for about 15 seconds and then plug it back in. Now start it up and drive.

This should fix you right up.

 

[washguy]

Alrighy ill see within next days what the dealership responds with TC waranty... he did say the drive axles had a bit of a loose in it thus him saying its like it nudges on something in TC... i will put all your inputs as hypothesis next time i go in.. ujoints and trans mount

Christopher It might behoove you to not give the dealership inputs from this forum....it could come around and bite ya ........remember "loose lips sink ships" dunno what the youngsters say? maybe" keep it on the down low".....just my .02 Wash

 

[brancky3]

Just saw on fb the green black wire in the cabin fuse box might be the same wire. If so easier tap and easier to hide.
Test anyone?

I've had this same hunch from the beginning. On Nissan / Infiniti cars they do the exact same thing as the brake snip but the wire is behind the fuse box. I assume it would be much easier to build a pigtail adapter for true plug & play if that was the case for us