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XH II XR8

XH XR8 trans changes down at 100km by its self to 3rd issue

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A couple of questions, on a 1998 XH XR8 what controls the kick down?

driving at 100kmph cruising with light throttle the trans will kick back to 3rd gear by its self, by pushing you foot to the floor will make it change back up again at high revs to top gear. at times jumps straight back to third but comes right for 50-100km or so then with no issue. a 200km trip could see it do it 3-4 times.

trans shifts smooth, functions normally other than this kicking down by its self.

 

any thoughts people?

 

cable? solenoids? sensor of some sort?

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With all BTR transmissions, the inhibitor switch on the side of the trans, controls the gear position...

 

It's common for the switch to wear out.

Put the dash cluster into diagnostic mode, then bring up the gear position indicator.

 

If the indicator readout changes, without you touching the actual gear lever, (while driving along, etc)

you know the inhibitor switch is faulty.

 

If it still does this, it could also be a TPS issue...

 

Are you sure it's not the torque converter unlocking?

If input sensors are out of whack, it can make the converter lock/unlock, at the drop of a hat.

 

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Lockup should occur between 85 and 90 km/h. Any more than about 15-20% throttle should kick it out of lockup.

If it's only kicking down to 3rd and dropping out of lockup, and only plays up at that particular speed and throttle opening, I'd put my money on TPS. If you flatten it at 100, still should drop down to 2nd.

If it was gear selector pot, I reckon it would show up at speeds other than that described (ie: at any speed when it's in D). If it's losing gear selector signal altogether, then it will go into limp mode, which is 3rd gear locked (no lockup clutch) at all speeds. Again, this would show up regardless of throttle opening.

Not sure if it stays in lockup while manually shifted to 3rd (Dave?) but if it does, then dropping out of lockup would only be TPS related. That would be another pointer.

I'll see if it will still lockup in 3rd in my mum's EL tomorrow.



Sent from my CPH1607 using Tapatalk

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Being a V8, it will have 2 TPSs, presumably one for the ECU and one for the TCM. 6s used the same sensor for both, for most models from the early 90s.

Sent from my CPH1607 using Tapatalk

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maybe its 2nd it drops to?.. it sits on about 2000rpm at 100kmph and when it changes its self down it slips around to about 4500rpm.  a stab on the gas to accelerate slightly faster speed seems to get it to drop back to the higher gear then doing maybe 2700ish rpm then again shortly after back normal 2000rpm for the 100kmph (ish)

 

not always exactly at 100 either could be 95-105

trouble is to get it to do it i could drive  50-100km down the road before it does it once. its not like it does it every time it hits 100kmph

 

from a standing start it changes up smooth and up perfectly. up and down shifts.

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that was on my mind how ever on a XH its a sealed trans so i cant check, dealer needs to. looks nice and dry with no leaks.

 

how ever i did notice today that when i select 1 gear and drive off it still changes right up to top gear. this is normally the inhibitor switch on the trans so will chuck one of those at it tomorrow hopefully if i can get one.

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4 hours ago, XH II XR8 said:

that was on my mind how ever on a XH its a sealed trans so i cant check, dealer needs to. looks nice and dry with no leaks.

 

how ever i did notice today that when i select 1 gear and drive off it still changes right up to top gear. this is normally the inhibitor switch on the trans so will chuck one of those at it tomorrow hopefully if i can get one.

 

The BTR/DSI/ION 4spd Auto transmissions are most definitely NOT sealed.

Of course you can check. :)

 

The filler plug, is a 16mm nut on the right hand side of the transmission towards the back.

Make sure you only use a six sided socket, (not a 12 sided) or you'll likely round off the plug hex.

 

The fluid should be a clean cherry red colour.

If it's a black/red, or brown colour, then it needs a service.

 

Only use TQ95 transmission fluid in BTR's.

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Thanks Dave good to know, i will check that as well. (I was working of what the service tech said on a previous car i owned (EF XR8 SVO))

 

I have solved the changing issue, I have only owned it for 4 days and this frustrated the crap out of me. the previous owner drove it for a year like it was (not every day.)

 

The plugs on the inhibitor switch on the trans were dirty and with a clean with some electrical cleaner the trans now works perfectly.

Will now shift manually as well and hold in a lower gear if selected. 

 

interesting enough when i was under it checking i see some muppet that has serviced the trans at some stage has put the pan gasket in backwards. will be put right when i service it at a later date. 

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6 hours ago, XH II XR8 said:

interesting enough when i was under it checking i see some muppet that has serviced the trans at some stage has put the pan gasket in backwards. will be put right when i service it at a later date. 

 

Did your Auto trans still have the clip on heat shield, covering the inhibitor switch area?

 

Are you seeing an extra rubber tab, sticking out the side near the middle of the pan?

That's a universal BTR pan gasket.

 

Some of the transmissions had a different casing/pan with more bolts.

 

The BTR 4spd Auto's, were used in Fords, Ssangyong vehicles, AND Maserati's.

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no heat shield not on it.

 

problem was very intermittent, could drive for an hour and it does it once then was fine. hot of cold. 5 minutes in or a hour. nothing constant about the fault. 

 

the gasket/ trans has two bolts on one side and one on the other, under the actual bolts there is no loop or gasket just a gap where a gasket should be. surprised it still sealing.

 

yes my GT-P also has one (4 speed) going to swap it for a 6 speed auto or manual once i get time.

4 speed has gone once but was rebuild under a aftermarket warranty. standard cooler not big enough was the issue in they say. (the 500hp the car is may have also played a part...lol)

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9 minutes ago, XH II XR8 said:

the gasket/ trans has two bolts on one side and one on the other, under the actual bolts there is no loop or gasket just a gap where a gasket should be. surprised it still sealing.

 

yes my GT-P also has one (4 speed) going to swap it for a 6 speed auto or manual once i get time.

4 speed has gone once but was rebuild under a aftermarket warranty.

 

Lol that's definitely a fail, with the gasket... wow! :o

 

What did the GT-P transmission do, when it failed?

 

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got rough shifts real quick and wouldn't change higher than 2nd from memory, warranty paid just on $5K to rebuild and that was probably 5 years ago or more.

 

was the family car but now just parked in my shed for odd cruise days.

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Only use TQ95 transmission fluid in BTR's.


Why?

Most Dex III ATFs have been improved to meet BTR specs. Penrite does a semi-synthetic oil that will definitely work in them, and almost any fully synthetic trans oil would also work in them.

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47 minutes ago, Mr Polson said:


 

 


Why?

Most Dex III ATFs have been improved to meet BTR specs. Penrite does a semi-synthetic oil that will definitely work in them, and almost any fully synthetic trans oil would also work in them.

 

I was led to believe I could use the Penrite ATF FS with Green writing on the bottle?

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I was led to believe I could use the Penrite ATF FS with Green writing on the bottle?
Absolutely can, that's what's in my mum's auto AU, and my brothers BA and a friend's BA, and all of their gearboxes drive fine.

I've even got Penrite FS ATF in my XF in the BW40.

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9 hours ago, Mr Polson said:

Why?
Most Dex III ATFs have been improved to meet BTR specs. Penrite does a semi-synthetic oil that will definitely work in them, and almost any fully synthetic trans oil would also work in them.

 

 

8 hours ago, Mr Polson said:

Absolutely can, that's what's in my mum's auto AU, and my brothers BA and a friend's BA, and all of their gearboxes drive fine.

I've even got Penrite FS ATF in my XF in the BW40.

 

A pan fill is only 4ltrs.

The torque converter has another 30ltrs or so in it, hence you'd be mixing fluids... unless you knew what was in there before?

 

Not the best idea to mix Mineral/Synthetic trans fluid I didn't think?

 

My reasoning is that actual TQ95 still exists for a reason?

I'd want to see some sort of viscosity info across the various available fluids, to compare.

 

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1 hour ago, SPArKy_Dave said:

 

 

A pan fill is only 4ltrs.

The torque converter has another 30ltrs or so in it, hence you'd be mixing fluids... unless you knew what was in there before?

 

Not the best idea to mix Mineral/Synthetic trans fluid I didn't think?

 

My reasoning is that actual TQ95 still exists for a reason?

I'd want to see some sort of viscosity info across the various available fluids, to compare.

 

Spot on. one would have to do a complete flush/Vac and even then you wouldn't get all of it.

I guess this is why log books are so important, you can see what oils/fluids were used in the past.

I would still like to drain the old stuff and put in the Penrite stuff, Ive been using the HPR5-40 FS in the benz 

and have never looked back. it is as good/better then the $30 a litre Mobil one oil

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I must admit my auto services have always been done by a mechanic with a flush machine, hook it up to the trans line and run the car, pumps old fluid out new fluid in, often takes 2x/3x times the fluid capacity to come out clean.

I've also been using Penrite for years, engine, diff, gearboxes (auto and manual), brake fluid, greases.


And Dave, as for why is TQ95 still on the shelf? Because Castrol is awful for updating their products, and representing and educating about their oils. I've been with Repco over 3 years now, and never seen a Castrol rep in either store I've worked in, and minimal product updates. Penrite I see a rep each fortnight, and continuous product improvements, new releases and product info.

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49 minutes ago, Mr Polson said:

 

And Dave, as for why is TQ95 still on the shelf? Because Castrol is awful for updating their products, and representing and educating about their oils. I've been with Repco over 3 years now, and never seen a Castrol rep in either store I've worked in, and minimal product updates. Penrite I see a rep each fortnight, and continuous product improvements, new releases and product info.

 

Yeah I meant TQ95 in general...

Apart from Castrol, Bursons do an actual TQ95, plus Valvoline too, and maybe others I don't know about.


Does Repco have a home-brand TQ95?

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