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ezeman

'92 RRC 3.9 auto struggles on hills

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So I got my 1st RRC through it's roadworthy, even got AC working, - love it, however. . . .

With 4 people in the car on the highway, any time i get to a hill it really struggles to keep its speed 80 kph (50 mph).

  • Subtle** pedal work to retain the same gear is pointless.
  • Hitting the gas before it slows too much resulted in downshifting and racing back up the speedo. Take foot off gas at correct speed, and repeat process.
  • If i left it too long and it drifts down to 60 kph, i'd have my foot firmly on the floor and it won't auto-change down, so i need to manually downshift. All other times gear change is fine - Maybe a bigger issue?

Same issue on both LPG and petrol.

Is it normal for the RRC to struggle in this way? At 80 kph, the car is sitting at very low revs but I would have hoped that there was enough grunt in a 3.9 V8 ignore road hills.

Maybe is it simply a difficult rev speed and its just matter of dropping down to 3rd gear at a road hill? Manual shifting on the slightly woolly gearbox still needs some practice.

Thanks, Kenny

** Is that the first time the word "subtle" has been used in a land rover forum?

I have searched for similar posts but cant seem to get lr4x4 search engine to work - maybe it's just me and engines :(

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Sounds like your kickdown cable has become detached to me, it's connected to the same place as the throttle cable.

If it has, then you shouldn't really drive it as you will knacker the box very quickly.

Sometimes they become detached inside the box, which is quite a bit of work to fix....

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You can't cruise comfortably in an RV8 at less than 2000 RPM because the power drops off anywhere below that generally. If your combination of tyre size and gearing is dropping your cruise speed down too far you'll end up in "kickdown hell" where you have to kick it down to maintain your speed, it speeds up, you ease of the throttle, it changes back up again and the cycle begins all over. Shifting it into 3rd can make it more bearable (there's a reason there's no gate between D and 3).

V8 autos are easier to drive when you're under geared than over geared and a lot of people swap out the standard 205R16 tyres for something bigger and then find it doesn't drive as easily as it did.

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Mines a manual but agree with Dave about power drop-off. I try to keep the revs between 2k and 3k most of the time.

Also - remember when Top Gear put some old cars on a rolling road?, there is a chance that anything up to half of your car's original power will have escaped over the years so you may well struggle to pull a couple of tons with brick aerodynamics up a hill anyway...

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Yup - it certainly feels like old age is taking its toll, and acceleration is pretty poor - already done 267,000 km (166,000 miles) so it's not surprising. Thanks Dave W, the tires are pretty big, so maybe a set of 2nd-hand shoes might help.

Bowie69 - i get kick down normally (totally hear Dave W description of kickdown hell), it just sometimes wont drop down a gear if i had pressed the gas too slowly allowing the revs to fall too far - does this still sound like a kick-down cable?

Manual downshift works a treat, so I'm still well mobile..

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166k on it's own should not effect the performance that much, I had a 3.5efi (15 horses down on yours) that had done 155k & still went well although it had a top end overhaul at about 120k. If anything has been done to change the overall gearing it will not help the situation & also don't expect saloon car figures from these vehicles as that's not what they are about - the engines were tuned for a compromise between both off & on road use plus the power losses through the auto-box, transfer-box & two diffs is considerable compared to a 'normal' car.

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166k on it's own should not effect the performance that much, I had a 3.5efi (15 horses down on yours) that had done 155k & still went well although it had a top end overhaul at about 120k. If anything has been done to change the overall gearing it will not help the situation & also don't expect saloon car figures from these vehicles as that's not what they are about - the engines were tuned for a compromise between both off & on road use plus the power losses through the auto-box, transfer-box & two diffs is considerable compared to a 'normal' car.

Good point G&T - don't really care how fast it is, as long as there's nothing wrong. My other car is a Saab Turbo Sport, it's only 2 litre but really quick, so I guess road-based comparisons are a bit skewed.

Thanks for all the advice guys - I'll swap tyres, do some compression tests, etc and settle into the slow lane.

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Regarding the kick down not working ive had older autos where above a certain speed it didnt wont to kick down. Never really sorted the problem but you could try shortening the kickdown cable a little bit using the adjuster at the throttle housing end. Tightening the cable should make it more prone to kick down

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Thanks SteveRK, I'll have a look for the kickdown cable and see what it's like.

The issue is more that it wont change down at lower revs, whilst under load (eg on a hill or gentle acceleration, whilst already in 4th) . I can have my foot on the floor and it won't change down - even taking foot completely off the gas pedal and putting it hard down doesn't do it.

Yet, on the flat, with out a load, it will kickdown no problem.

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If there is no kickdown then thats clearly a gearbox problem. I'm no auto gearbox expert but with a load on the vehicle in 4th the engine will be less able to 'rev up' and this will have some kind of knock on effect with oil in the torque converter. There is an oil filter in the gearbox sump that I have heard reports needs replacing eventually it may be down to restricted oil flow through the torque converter generating this problem of reluctance to kick down. There may also be engine power related problems as well compounding the overall lack of torque but it does sound like the gearbox is not behaving as it should.

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I have the same problem with a 86 Rangie that runs on gas in Brisbane

I have started to work my way though things.

I am by admittance a diesel person, have 3 diesel defenders so not great with the tuning of the v8 . But my brother came over from the uk at Christmas and he is more into v8's . So we spent a few days tuning it and going through a few things.

First was that my kick down cable need adjustment. This made it kick down a bit better. But still sluggish after new spark plugs leads and dizzy.

So for me next more is to get rid of the horrible crappy Holly carb on it and replace with SU's . I found a set of SU with the gas stuff on it in Aldelaide so waiting for them to get to me and then going to get rid of the holly . But at the same time that I replace the holly i will look at the cam as I do think it may be the cause of the problem as a few have told me the gas does have a habit of wearing down the cams

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Why on earth would running on LPG affect cam wear?!!

Worn cam could well be causing you to be down on power, and I guess it might affect LPG more than petrol (though I don't know), but running on LPG won't make it wear faster!

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I totally agree with you. I can't see how the lpg can wear down the cam but that is what everyone tells me what happens if you run on LPG too much.

Can't see how but will have a look and see what the star of mine is when I change the carb

(null)

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As far as I'm aware (and I can't find original research, only quotes from pro-LPG sources, so approach with the usual caution), wear to valves is likely to be slightly worse as LPG burns much more cleanly so there are no soot deposits, but the lack of soot and acid combustion by-products should actually extend oil life. In other words, assuming the same maintenance schedule your cam ought to wear less when running on LPG, not more (which doesn't necessarily mean a longer life if LPG is more sensitive to cam wear, which anecdotally does seem to be the case).

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