Long story short, I replaced my stock SRT trans with a trans from a RT due to the trans kind of sliding into 3rd, and converter with a Mopar performance converter. 1st two passes I pretzel two stock driveshaft's, 426 problems. I got a DSS one piece shaft installed, and was not happy with my ET. did some logging and attributed to the DS. Fast forward a bit. I totaled the car in August and I bought it back. While I'm waiting to take it to the body shop, I am trouble shooting the knock issue some more. I put a stock shaft in it and the knock is still there. I went back and locked at some datalogs that I recorded before the trans and converter install. These logs were knock free. Is there a possibility that either the trans or converter is causing my knock issue?
I don't remember what it was part throttle. At the track... 1st gear would start at 6 and decrease, 2nd would start at 4 and decrease, and 3rd was 0. On the street it really varied, but I want to say it was around 4-6. I would get an occasional 1-2° of long term knock, but nothijg consistent. I got with Brent thinking it was a tune issue, but such was not the case.
Kind of surprised you are getting KR so early and less once you get into 3rd since more load is applied at those points. So when you mash the gas the KR spikes right up to 6 and then decreases through the rest of the gear ? Did Brent comment as to what he thought it might be ? Did he send you a revision to try and see if it affected the KR ?
That is correct. Mash the gas and it spikes then decreases, on the track at least. The street I think it was constant. Brent and I had several discussion when I thought it was tune related. I had him send me the original tune file in case the tune had somehow became corrupted. He had me add some race gas and add some fuel and timing as well, nothing changed. After that I associated it to harmonics with my DSS driveshaft. I figured the shaft was rubbing in the tunnel, before I could troubleshoot anymore the car got wrecked. I bought it back and fixed the driver's side suspension so that it would be driveable. Swapped in a stock driveshaft, took it out for a quick spin around the block and the knock is still present. I'm planning on replacing the motor mounts as well as the trans mount. Current motor mounts are 6 spd mounts that were put in new, in July 2015 when the 426 was installed.
I think it will be too hard for a diagnosis over the forum. Sounds like you have alot to check on . I have a bit of mystery KR myself at Part Throttle in a certain RPM window.... playing with timing helped but didnt eliminate it. Some KR is just going to be when dealing with a built motor, but not at WOT.... I think the most usual suspect to check is exhaust and bolts, make sure everything is tight and nothing is rubbing ...
That's what I have been doing. Ran fine until I swapped the trans and put the Jeep converter in and twisted the the 2 driveshaft. Only reason I looked at the logs after I got the DS put in as because I was unsatisfied with my ET. I do appreciate the input. I just was looking to see if it's possible for a trans or converter to cause knock. Sounds far fetched to me. But when I look at things it seems like a huge possibility.
I dont think they are a likely case but do believe it is possible. Did you log often before all this went down ? Was curious if you had one or two logs fro dyno or street you were comparing them too of you log all the passes at the track.
I don't remember how close the latest logs were before I swapped the trans. That was the beginning of last year. I twisted the shafts on the first passes of the season. So my first track passes and logs were in may. I need to get in the habit of transferring logs the day I record them.
Well some people will have a log of when the car was first tuned on the street etc and never look at a log again.... then they go race in different weather and a different amount of load on the motor and never know if they are getting KR or not.
I would do random logs at random times to make sure everything was up to par. Tried to make sure I did a log or 2 every few track days
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