Transmission load indicator

Submitted: Wednesday, Apr 21, 2010 at 17:56
ThreadID: 77902 Views:2413 Replies:4 FollowUps:9
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Can anyone suggest a method of measuring the load on the manual transmission of my 3 litre TD hilux during towing?

It crossed my mind to fit a boost gauge to the inlet manifold, but feel without a very large gauge the reading may be too coarse to accurately assess load.

Is it a possibility to tap into the drive-by-wire current, or does that only give me throttle position?

Exhaust heat sensor could be another, but probably slow to respond.

Any thoughts folks?

Paul
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Reply By: Olsen's 4WD Tours and Training - Wednesday, Apr 21, 2010 at 18:01

Wednesday, Apr 21, 2010 at 18:01
EGT suffers very little lag and provides the best option that is how the truckies do it
AnswerID: 413799

Follow Up By: Member - Paul S (VIC) - Wednesday, Apr 21, 2010 at 18:22

Wednesday, Apr 21, 2010 at 18:22
Thanks for that.

Would fitting it just after turbo be best option?

Cheers,
Paul
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Follow Up By: Fab72 - Wednesday, Apr 21, 2010 at 19:16

Wednesday, Apr 21, 2010 at 19:16
Yup...best place for it. As Olsen said, that's how the trucks do it and it does respond quickly.
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Follow Up By: Olsen's 4WD Tours and Training - Wednesday, Apr 21, 2010 at 20:27

Wednesday, Apr 21, 2010 at 20:27
Pre-turbo gives you the best indication of the actual combustion temperature, but as mentioned below, is a bit more difficult. As a measure of load, just go for post turbo
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Reply By: Member - Graham H (QLD) - Wednesday, Apr 21, 2010 at 19:25

Wednesday, Apr 21, 2010 at 19:25
Pre turbo is actually the best but costly to fit unless your manifold is predrilled.

After Turbo temps are about 200deg less than manifold so just allow for that


Have a read of this thread noting the temps quoted in the replies.

http://forum.candm.com.au/showthread.php?t=3900



AnswerID: 413811

Reply By: Member - Jeremy W (SA) - Wednesday, Apr 21, 2010 at 20:12

Wednesday, Apr 21, 2010 at 20:12
Re: ... measuring the load on the manual transmission ...

Just thought I'd throw this into the ring - measure the tail shaft torque:

http://www.sensotec.com/pdf/9300.pdf

Hate to think of the price etc. etc. etc. - there may be something simpler.

Jeremy
AnswerID: 413817

Follow Up By: Member - Paul S (VIC) - Wednesday, Apr 21, 2010 at 20:57

Wednesday, Apr 21, 2010 at 20:57
Wow that's one bit of mean gear.......doubt if I'd get approval from $WMBO, although this whole exercise is for her when she relieves me on long driving stretches.

Basically we tow in 4th only, except when travelling down hill or even slight declines, which are sometimes hard to judge. I reckon I can tell by just feathering the throttle and if we drop speed I shift down from 5th to 4th.

She, however is not confident enough to use this technique, so I figured a gauge to indicate load would be an ideal aid for her.

Thanks anyway Jeremy..........maybe if my numbers come up on Saturday......

Cheers,
Paul
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FollowupID: 684005

Follow Up By: Member - Nick (TAS) - Wednesday, Apr 21, 2010 at 21:11

Wednesday, Apr 21, 2010 at 21:11
With our Cruiser(HZJ105 with DTS turbo and big I/C), I notice that it runs about 50-60 Deg C cooler towing in 4th than 5th on the flat, I never try on hilly stuff.I very rarely tow in 5th but EGT shows it better in 4th.
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Follow Up By: Member - Paul S (VIC) - Wednesday, Apr 21, 2010 at 21:27

Wednesday, Apr 21, 2010 at 21:27
Thanks Nick. The lux is fitted with diesel/gas and from what I have read, the exhaust should run cooler than straight diesel. So don't know if it would indicate as well as yours.

In fact the higher the load, the more LP I use in proportion to diesel.......so more gas.....cooler exhaust?? I guess only an EGT gauge would solve that question.

Anybody out there with diesel/gas & EGT to help answer this?
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FollowupID: 684018

Follow Up By: Member - Oldplodder (QLD) - Thursday, Apr 22, 2010 at 08:03

Thursday, Apr 22, 2010 at 08:03
If it is for SWMBO, you are opening another can of worms.

Put a boost gauge on mine, and when she took over the drivers seat on a trip said sit on 11 to 13 psi boost (with CT on).

Now I am trouble because she keeps chasing the boost gauge, it is either too high (common) or too low (ocassionally). And she complains she has to watch the speedo, and the EGT, and the water temp gauge (after we got a cracked head and I wasn't driving), and yeah, she ocassionally looks at the road so we don't run into something. :o)
I Still watch the oil pressure gauge and the two volt meters for the two batteries as a passenger, otherwise she would be really complaining. Think there is a couple of other gauges there too, like tacho and fuel.
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FollowupID: 684057

Follow Up By: Member - Jeremy W (SA) - Thursday, Apr 22, 2010 at 08:55

Thursday, Apr 22, 2010 at 08:55
Hi Paul,

This problem - load measuring - has been around along time and I've put off looking for a "cheap and easy solution" until I read your post - gives me something to think about!! Cheap is relative - instrumenting a shaft is easy enough but a real "pain in the butt" !!

Some larger (c. 4000 eshp) gas turbine engines have readouts to indicate the engine torque, PRM and power they run at one speed so if you want more power you just pour more fuel into them as you increase the load and up goes the torque!!

Jeremy
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FollowupID: 684064

Reply By: Bob of KAOS - Thursday, Apr 22, 2010 at 08:40

Thursday, Apr 22, 2010 at 08:40
Paul

Although an indirect measure, the percent throttle opening value gives a pretty good indication of whats going on. For instance, with cruise control engaged, the throttle opening varies to maintain a constant speed - I measure the effect of turning the LPG system on and off.

So throttle position is not a bad proxy for torque (or transmission load).

Alternatively, the instantaneous fuel consumption in L per hour, or L per 100 km also give an approximation to torque.

All of the above are easily measured by plugging a Scangauge into the OBDII outlet
AnswerID: 413872

Follow Up By: Member - Paul S (VIC) - Thursday, Apr 22, 2010 at 10:27

Thursday, Apr 22, 2010 at 10:27
That's a great suggestion Bob..........the solution may already exist on my dash as I can scroll to the 'inst. L/100kms' readout instead of having it set at 'outside temp'.

Will do some testing with & without towing the camper.

A L/100kms readout obtained from normal 5th gear non towing, such as slight inclines at 110kms/hr, could be used as my max for towing.

My thanks to you Bob and to all forumites who offered advise & suggestions .

Cheers,
Paul
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FollowupID: 684077

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