Jump to content
SAU Community

Help On Finding Transmission Problem

Peacekz
 Share

Recommended Posts

Peacekz Rookie

Peacekz

Posted
Posted (edited)

Hello Everyone.
Please help me identify problens with my gerabox.
I have a BNR32, with nice built RB26 and S362FMW runing 1.2-1.4 bar of boost.
I have broken 2 sotck trannys so i ordered OS-giken 5 speed kit with input shaft and center plate.
Installed it and my problem seem to go away... until i get to drag strip.
While making my starts better and better tuning launc and torque split finaly i set up launch to 7200 and forgot to remove 50% fo torque from front i didn ont start at all, the car didnt even moves.
later in garage we found that it is counter shaft broken right after 5 gear.
Here is a picture

KdoqeRZ8bSI.jpg

If you look closely you can see wear on the shaft in the place it inserts into a wall between gearbox and transfer case.
What can be the cause of this? I mean the cause of breaking shaft i guess wear shows that shaft was not proppely secued and had a play.
All kind of bearings including bush in the crankshaft?

Edited by Peacekz
89CAL Grand Master

89CAL

Posted
Posted

You haven't listed your power, which really tells more of the story then how much boost you are running. Depending on power/torque, with a 7200rpm launch with power going to all 4 wheels, it might just be something that should not have been done.

Better photo of the fracture?

Peacekz Rookie

Peacekz

Posted
  • Author
Posted

Hello Sorry no better foto.

I dont know exact power. it should be around 600 HP i think taking in consideration i load 89% of 720CC injectors and making 11.4 ET with bad start.

Soru english is not a native, what do you mean by fracture? the place where i see a wear on the shfaft where it contects needle type bearing or the photo of the the shaft where it was broken?

Yes i understand that was my mistake to launch on 50/50, but i'm quite expiriencde in gt-r's and never seen countershaft failure like this. There is always a weaker point than these solid 29mm stell shaft.

89CAL Grand Master

89CAL

Posted
Posted (edited)

The middle shows the last part that hung on then twisted and snapped. Will have to find my failure analysis book, haven't had much to do with metal failures lately. That is a very clean break. I had a similar looking failure with a rear drive shaft. Almost identical actually.

That was from a high rpm launch

Edited by 89CAL
Peacekz Rookie

Peacekz

Posted
  • Author
Posted

One more thought -the break surface is polished by rotating during the car was worked. And we pulled the car to the garage with the engine started so the brakes was good. So i guess the surface will not tell the truth. I guess the shaft was broken due to it has a vertical play.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • GTSBoy
      Duncan's V37.......race car?

      By GTSBoy · Posted

      I hope it's actually possible. This is a write off in insurance world.
    • GTSBoy
      Nismo GT Pro LSD configurations

      By GTSBoy · Posted

      Yup. 2-way with shallow ramp angles. Still works.
    • Duncan
      Duncan's V37.......race car?

      By Duncan · Posted

      That was the first session so not a lot to take from the day. It was low 20s ambient and the coolant had got to 110 (and obviously had some pressure!) so that still needs to be addressed. I haven't downloaded the data yet but will. I had refilled the auto trans with Redline DT6 because it claimed the best viscosity I could find at 100o. It wasn't really long enough to get a good feel for that; while the trans got to 100o in the session it still wasn't shifting crisply as I hoped. I think I'll try a few more sessions before judging. No steering motor overheat but I'd hope not in only 1 session! But finally the suspension; it was night and day over the standard stuff and the car was a couple of seconds quicker on the same crappy tyres, which is a huge difference. I'll stick with that and get some sway bars and a mechanical diff sorted too and see how that all goes together
    • CRSKmD
      R32 Sedan - Grip and Drift (have my cake and eat it too build)

      By CRSKmD · Posted

      I guess it’s partially a compromise of how my car is used, wanting to be able to switch from drift to grip with track side on-car adjustment. Also partially with the way the knuckles are set there is more static camber but less dynamic camber gain. 
    • Duncan
      Duncan's V37.......race car?

      By Duncan · Posted

      OK, so update from the track day on Friday It was a classic "an unfortunate series of events'. There were a few cars around and when i checked my mirror coming out of the fish hook I notice some smoke from the rear of mine. Looked again and it was getting much worse, I figured I'd blown a turbo or something to got off it and pulled off the racing line. However.... since it is a left hairpin into a right kink, I was on the inside of the next corner. There was a car passing me on the left and a big drop off over the ripple strip on the right......and someone had knocked the witch's hat that was on the apex about 1m onto the track. So, between those 3, I decided to mow down the cone and not damage my car/the other car. Right choice, but surprising result.  The car decided the cone was a small pedestrian so it blew the rear bonnet hinges up to protect their head in the upcoming person to car impact....I didn't see that coming and like an airbag deployment it happened super fast. Straight into the pits from there, everything was driving fine but it became clear it was a coolant leak not smoke, it was billowing up onto the windscreen. Onto the trailer and home. I'll do a separate thread about the repair (once I work out what it is ), but the immediate problem was the bonnet wouldn't open because the front was pinched onto the front bar and would not release. Ultimately we unbolted the hinge from the bonnet, pulled it back a little and it released from the front OK. "There's your problem", the top radiator hose had popped off at the radiator.
×
×
  • Create New...