ken
Isuzu Junior
Posts: 87
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Post by ken on Feb 24, 2006 17:14:26 GMT 11
I put this up for discussion in this section even though it is about gearboxes.
When I fitted a turbocharger to my Nissan Laurel 2.8 I did some investigation on the INTERNET and found that it was great for towing in fifth gear. However some had found that after a while fifth gear failed. This was not just a problem with Nissans but ALL makes. They said fifth gear was designed for economical highway cruising. It is certainly easier on the gearbox in 4th as the drive is straight through and no strain on it.
Anybody any thoughts on this?
Ken
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Post by geeves on Feb 24, 2006 18:28:02 GMT 11
Definatly dont tow in a mazda/ford ute in 5th or the gearbox will be toast in 20000k but Ive never heard of this on other makes.
On a side note the new Toyota Prado with full time 4wd seems to be throughing its cogs out of the cot if you do too much 4wding in it. A new member of one of the clubs I belong too just had to spend a fortune on a center diff rebuild which the warrentee wont pay for. It apears that the official Toyota response is "center diff lock is for emergencies only and not for prolonged use" Watch this space for results of the court case
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Post by draganlada on Feb 24, 2006 19:26:26 GMT 11
I agree with the theory 5th gear is not for towing coz this is an overdrive and by most makers of gearboxes weekest link in the gearbox.With lada gearbox it is not recomended to accelerate in 5th gear(to maintain life of your 5th gear).
Re center diflock;lada book saids use center diff lock only when you are expecting to loose traction of one or both wheels of one axel and disengage it after passing the obstickle DO NOT DRIVE WITH CENTRE DIFF LOCK IN "LOCKED"POSITION!
I'm using my centre diff lock all the time on sand dunes driving and sometimes am engageing it just before entering mud hole or starting rock klimbing and disangageing it after mud hole or dificult rocks and continue offroading in all wheel drive mode (this is in my lada niva not the isuzu mu).
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Post by geeves on Feb 24, 2006 20:10:17 GMT 11
Interesting. My understanding was that a locked center diff or transfer case was ok on any surface that allowed some give which I would take as any non sealed road although there was some discusion on the nz4wd forum a while ago about useing locked 4wd on wet seal. Also several of the full time 4wd vehicals automaticaly lock the diff when in low range and the early 4wd rally cars used a permanantly locked xfer case so it was hard 4wd all the time even dry seal.
Trying 4wd with hubs locked in an Isuzu will break things that are hard to fix.
Different gearboxes are built different ways The only Isuzu gearbox failures Ive heard about have bee due either to water getting in or the seal between the xfer case and gearbox failing causing all the oil to gointo the xfer case
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Post by Yarno on Feb 25, 2006 8:08:26 GMT 11
How many Isuzu boxes have you guys heard of being changed for any reason?? bugger all except the ones that haven't had oil in them (by filling gearbox and not transfer or somthing like that). I have heard about nissan fifths and problems with toyota boxes. So I would say the Isuzu box is pretty strong and it probably won't be a problem towing recommended weights (1600kg Jack/trooper towbar rating (same g/box)) and if towing alot more I would only use 4th....
The newer Prardos have torque on demand type system in them which should mean that you don't even need centre diff lock, but obviously these systems are never as positive traction as locked gears. I cannot see toyota wining that court case, they put the button in there, and if it wasn't spose to be used they shouldn't have...
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Post by draganlada on Feb 25, 2006 11:14:17 GMT 11
I nave changed my isuzu gearbox due to excesive bearing noise.When noise started I didn't change oil but only toped it up.It needed only few drops of oil to top up cold gearbox and same thing with transfer box.After few months and 10 K km later,noise became unberable and I had to do something.I had couple of quotes to replace bearings only for $1100-1600 + everything extra what can be found ones gearbox is opened (up to $ 2500).I was afraid of those extras and went for cheaper option, second hand gearbox for $800 fitted with 6 months waranty.
Don't know if it made my bearings to fail but my gearbox was filled up with automatic (red coloure) transmission oil?
Guy who I bought my mu from showed me receipt of recently service of timing belt,brake fluid, coolant and transmision and diffs oils.
Why will somebody fill manual trany with auto oil ?!? BY MISTAKE OR TO ACHIEVE SOMETHING ?
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Post by geeves on Feb 25, 2006 15:42:07 GMT 11
Alot of people use auto trans oil in gearboxes and apart from being able to get out throught seals easier, there is nothing wrong with it.
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Post by mulover on Feb 28, 2006 18:14:55 GMT 11
I'm sure that if you used 5th gear when heavy pulling then u=you will stuff it, but this would mean that you would be labouring the engine too. I just use 4th if the motor is struggiling and feed her the fat then hook 5th on downhill,s etc, then back to fourth when it gets tough again.
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