79series 5th gear

Submitted: Friday, May 12, 2006 at 15:52
ThreadID: 33830 Views:2616 Replies:5 FollowUps:9
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I have a 79series Landcruiser tray with an aftermarket turbo which i often use for towing a 4.8m boat fairly long distances. Several people have warned me never to tow in 5th as it is likely to be damaged. Its always a temptation to run in 5th especially after fitting turbo. I have mostly heeded these warnings but find it frustrating driving in 4th reving at 3000rpm at 100k.Fuel consumption also goes up to around 16l/100k at these revs.
Any comments re towing with this vehicle would be apreciated.Is there a stronger gearbox that cen be fitted.
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Reply By: Member - Phil G (SA) - Friday, May 12, 2006 at 16:09

Friday, May 12, 2006 at 16:09
Tony, your vehicle has the R151 gearbox. The shaft that goes into the transfer can break - Toyota will happily sell you a stronger one, if it hasn't been replaced already.

The factory TD 79series has the stronger H150F gearbox and also has a different transfer case. It hasn't had problems. I don't know anything about the logistics of doing a swap, but without doubt, it wouldn't come cheap, and its possible that other modifications such as tailshafts etc may be needed.

I would be surprised if there was any significant difference in fuel consumption between 4th and 5th gear towing.
AnswerID: 172318

Follow Up By: TroopyTracker - Friday, May 12, 2006 at 16:38

Friday, May 12, 2006 at 16:38
Got to agree with Phil here. Have read peoples comparisons between towing in 4th and 5th and results were very similar, some actually better in 4th. I have the H150F and still don't tow in 5th as I tow alot of weight for alot of k's compared to most. Gearbox rebuild-some change from 3k, so even if you're using an extra teeny tiny bit of fuel every trip doubt it's worth it.
Matt
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Follow Up By: The Rambler( W.A.) - Friday, May 12, 2006 at 23:22

Friday, May 12, 2006 at 23:22
Phil, Can you tell me which box I have in my 2001 78 series Troop Carrier as I have heard there are some problems with the connecting shaft to yhe gearbox in models between 2000 and 2003--so far Ihave had no problems(140000kms) but Iwonder if it might be advisable to get the stronger shaft fitted before doing more bush trips as Ido go in fairly remote places.
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Follow Up By: Member - Phil G (SA) - Friday, May 12, 2006 at 23:34

Friday, May 12, 2006 at 23:34
The Rambler,

Yes, yours is one of the affected models (I assume its the diesel 1HZ motor). Had a friend with a 2000model, same as yours and at 100,000k, Toyota advised him to have the shaft replaced, which he did for peace of mind. Given that you can get stranded by a broken shaft, I'd be seeing a Toyota dealer and asking for their advice.
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Follow Up By: lost - Saturday, May 13, 2006 at 16:57

Saturday, May 13, 2006 at 16:57
what sort of money is the stonger shaft from toyota.
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Follow Up By: Member - Phil G (SA) - Saturday, May 13, 2006 at 20:56

Saturday, May 13, 2006 at 20:56
Lost,
i'm not sure, but I think its about a $600-800 repair.
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Reply By: Member - Tony C (VIC) - Saturday, May 13, 2006 at 11:19

Saturday, May 13, 2006 at 11:19
Thanks for the advise Phil and Troopytracker. I will look into having a stronger shaft fitted.
AnswerID: 172475

Reply By: The Rambler( W.A.) - Saturday, May 13, 2006 at 21:20

Saturday, May 13, 2006 at 21:20
Thanks Phill and I will be looking at changing to the stronger shaft as it would be very expensive to retrieve a vehicleout bush. A guy I met (Trevor Baker) had his go at 117000kms. and had it repaired at Robson BrOS. in Perth and it cost him about $900 all up which is reasonable considering the gearbox has to come out to do the job.
AnswerID: 172572

Follow Up By: Member - Phil G (SA) - Sunday, May 14, 2006 at 09:21

Sunday, May 14, 2006 at 09:21
The dealer might be able to look up their computer and tell you whether your vehicle has the earlier shaft.
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Reply By: Member - Barry C (NT) - Saturday, May 13, 2006 at 23:22

Saturday, May 13, 2006 at 23:22
Our 2005 LC 79 turbo ute has only 200 RPM difference between 4th and 5th so not that much there for serious fuel issue is there?

By two bobs worth.

Barry
AnswerID: 172589

Follow Up By: Member - Tony C (VIC) - Sunday, May 14, 2006 at 08:11

Sunday, May 14, 2006 at 08:11
Barry
Mine has a differance 800rpm between 4th and 5th at 100kph so must be different ratios in your later model .I have never towed for long periods in 5th so wouldnt have known if fuel consumption dropped much. From the comments i take it there's hardly any differance to worry about. My other concern is not so much fuel but wether its to hard on the 1hz motor reving at around 3000 for extended periods towing.
Thanks for your reply .
Tony
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FollowupID: 428238

Reply By: Member - Roachie (SA) - Sunday, May 14, 2006 at 10:13

Sunday, May 14, 2006 at 10:13
Not sure about Toyotas, but with my GU Patrol 4.2TD, the BIG difference between towing in 4th and 5th is the EGT. The manifold temperature when travelling at around 100k/h DROPS by around 100 degrees C if I drop the old girl back to 4th gear after working her at around 2050 revs in 5th. Revs go up to around 2500, but temp DROPS from around 530oC to around 440oC (these temps are very "ball-park" as the actual temp varies considerably depending on head winds, gradient etc).
Just to expand on the matter of gradient.......even a slight uphill section of road will see the EGT rise by 60 to 100 degrees.
My camper trailer weighs around 1200kg and I do drive in 5th gear as long as the EGT gauge tells me that it is sustainable. I also tend to be guided in my gear selection and speed, by keeping an eye on my Boost gauge.
IMHO anybody with a turbo vehicle, especially an aftermarket fitted one or one that has been tweeked, MUST fit the EGT gauge as a minimum and preferrably a boost gauge as well.
My Patrol was a 2000 model that suffered from the 5th gear spline problem and Nissan replaced it at around 80,000klm under warranty, BEFORE it actually collapsed.
My advice is that it is (or should be) okay to tow in 5th gear in the right circumstances. By that I mean that you should drop back to 4th gear as soon as you strike a slight hill or if you are aware there is a head-wind etc. Basically, you should never make the vehicle labour in 5th gear.
Just my opinion and may not be relevant to your Tojo.
Cheers mate
Roachie
AnswerID: 172607

Follow Up By: Member - Tony C (VIC) - Sunday, May 14, 2006 at 15:26

Sunday, May 14, 2006 at 15:26
Thanks for your helpful advice Roachie.I had Denco turbo and 3'' exhaust fitted when i'd done around 120000k and have done 30000k since. This mod made a big difference to an otherwise fairly sluggish vehicle.I have not had boost or EGT gauges fitted(to be honest i've not heard of an EGTgauge till now)Do you find boost gauge a help?
Cheers
Tony
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FollowupID: 428272

Follow Up By: Member - Roachie (SA) - Sunday, May 14, 2006 at 17:25

Sunday, May 14, 2006 at 17:25
Tony,
Check out www.thermoguard.com.au/

There is a lot of info on there about the benefit of EGT gauge etc.

I've gone one step further and now have 2 thermocouples feeding the same gauge (via a DPDT switch). One thermocouple is in the exhaust manifold, just above the turbo.......the other one is in the dump pipe using the plug/bung that the Denco system provides. It is quite amazing how much cooler (or should I say, "less hot") it is in the dump pipe compared to the manifold.

I only use the boost gauge to show me how much right boot I'm giving the old girl; I don't think it's as important as the EGT gauge, but still nice to know how much air pressure the turbo is pushing.

Cheers

Roachie
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FollowupID: 428277

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