| Author | Message | ||
     Jon Steinberg New User Username: amanda_ripanykhazova Post Number: 13 Registered: 05-2020 |
Does anyone know what causes gearbox racing on a 96 Brooklands please? My engine has lost all element of poke at high speeds. At the same time, all attempts to use the accelerator above 30mph except in the gentlest of ways result in what seems like part-throttle kickdown, - followed by very considerable engine racing! (obviously with no torque converter engaged) I had had similar symptoms before with Aston Martin V8s, and it meant gearbox seals were leaking. When fluid got low enough, the torque converter would no longer engage until the fluid levels were put back to normal. This time however filing up with gearbox fluid doesn't cure the problem, though the levels were admittedly dangerously low. The box uses about a bottle a year and checking under the car a month or so after re-filling, there is no gearbox leak. | ||
| Mark Aldridge Frequent User Username: mark_aldridge Post Number: 689 Registered: 10-2008 |
Jon, does the gearbox leak when the engine is running. Also check the kickdown switch under the throttle pedal is not sticking. (I assume at 1996 there is still a kickdown switch as on earlier SZ series cars). Is the vacuum modulator on the gearbox OK. Mark | ||
| gordon le feuvre Frequent User Username: triumph Post Number: 357 Registered: 07-2012 |
Jon/Mark, Not too much experience on late (92-98) cars with 4 speed trans, but I do not think they have same kickdown switch as GM400 (if this switch sticks will ONLY change up at max revs in each gear). I think all linked through engine management systems?? Jon, normally if trans low car will not move, trans pump will need to refill convertor to get drive which normally comes in with thump as engine revs are high. Some one must know more about this late gearbox, but my experience limited as in my dealings box has been very reliable! | ||
| Jon Steinberg New User Username: amanda_ripanykhazova Post Number: 14 Registered: 05-2020 |
Well. I don't know enough about gearbox modulators to know whether this could be the problem but is there anything different enough about this particular gearbox to make this a RR/B specific problem? Can I pull into a (generic) transmission shop and ask around? (No, I don't think I am losing fluid at the moment so I don't THINK I am susceptible to being told that I need a complete gearbox rebuild job, in the way that those shops sometimes do whatever-the-problem) Interestingly, with the complete loss of poke allied to this problem, it does look a bit like an engine management problem. but if that is the case, shouldn't something turn up on a OBD11 check? | ||
| Robert J. Sprauer Frequent User Username: wraithman Post Number: 637 Registered: 11-2017 |
Gearbox would be a GM 4L80E the electronic evolution of the TH400 gearbox | ||
| Jon Steinberg New User Username: amanda_ripanykhazova Post Number: 15 Registered: 05-2020 |
Thanks for that, I'll pursue enquiries that way, unless it IS an engine management issue! | ||
| Anton de bloch Unregistered guest |
I had this problem with my Chevrolet Impala. It is was a reasonable fix. Needed a Torque wrench on the left side of the box. I did not do the work. Go to a GM dealer and explan all the problems in detail. (Message approved by david_gore) | ||
| Jon Steinberg New User Username: amanda_ripanykhazova Post Number: 16 Registered: 05-2020 |
Thanks for that, and thank you to David for letting this post go through, where my easiest course is to use one of the thousands of local GM transmission dealers! | ||
| Jon Steinberg New User Username: amanda_ripanykhazova Post Number: 17 Registered: 05-2020 |
There appears to be a TSB# 01-07-30-002D on this "engine racing" problem with the 4L80E gearbox and somewhat mysteriously, there is talk on the internet of some sort of 'quality aftermarket upgrade' to the gearbox | ||
| David Gore Moderator Username: david_gore Post Number: 3777 Registered: 04-2003 |
Jon, Happy to help when we can - many of our members also have interests in vehicles other than RR/B models. We are all enthusiasts who have benefited greatly from the shared experience and advice of our contributors and reciprocate in kind when we can help out. | ||
| Omar M. Shams Grand Master Username: omar Post Number: 2072 Registered: 04-2009 |
I have struggled with this thread for a while. What exactly does racing mean? I always thought of racing as a competition where candidates compete against each other against the clock. This is different racing you all seem to be talking about. | ||
| David Gore Moderator Username: david_gore Post Number: 3780 Registered: 04-2003 |
Omar, Engine racing is a way of describing engines operating at RPM greater than idle whilst the vehicle is stationary or not in gear. It is usually associated with inappropriate settings, binding accelerator linkages or a component failure. It is not the same as a carburettor engine operating at a fast idle until the engine warms up and the engine slows to normal idle speed. |
