Help !odd problem with classic RR

bit about the RR first , its a 3.5 auto, had a new cam last month , new plugs leads , distributor ,rotor arm . it starts well and runs fine around town , the problem starts on open road ,

if I am driving on a long clear stench of road ( motorway etc ) it runs fine until it gets in to top gear . at around 45-55 mph ( 3000 revs ) it feels like its flooding I get a lot of vibration from the front , lack of power , no acceleration . if I kick down and get passed 55mph let it change up again it feels a lot better , but is still a bit 'lumpy'

I have had the timing checked by D.J Ellis (

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) ,highly recommended ! and general check over every thing looked ok

Any one have any ideas on this ? or is it back to D.J Ellis and lots of cash to find the fault ???

paul

Reply to
paul moloney
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Which auto box have you got? Three or four speed??

Graeme

Reply to
Graeme

its the 4 speed one ( 3 selectable gears )

Reply to
paul moloney

Bummer - if it was the ZF with four forward and one reverse then I'd have suggested some problem with the topmost gear/final drive in it - I do not know if the 3 speed has a similar gizmo?

However that is a bit 'off the wall' given that it was all work done on the engine? I'd hazard a wild guess at the cam itself if all the other top end bits were renewed too?

Reply to
Graeme

Is it the smell of roads in general you object to, or is it just a particular road?

Reply to
David French

On or around Thu, 25 Dec 2003 10:21:06 -0000, "Graeme" enlightened us thusly:

it is the 4-speed...

the 'box will "lock up" at about 50 mph give or take a few. when this happens the revs drop. What actually happens is that a clutch is engaged in the torque converter, which effectively removes it from the equation, this is known as the "direct drive clutch". This drops the revs back to about

2000 or less. If you put it manually into 3rd, you'll remove 4th gear and the DDC from the equation. You should be able to drive up to about 80 in 3rd. see if she'd running smoothly in this configuration, then try in 4th-DDC at about 70, either by flooring it a bit and then letting it change up at 70, or by holding it in 3rd, and then moving it back to D. I fit's smooth at 70+ speeds in 4th-DDC then I'd suspect the engine tuning. You might have a flat spot or such at 1800-2000, which doesn't show at lower speeds since the revs are higher.
Reply to
Austin Shackles

Bit of a Freudian Slip as i had the M6 in mind !

paul

Reply to
paul moloney

Austin this makes a lot of sense , as I cant get it to do it in any other gear ,

just checked the oil level on the box and its a bit high , sort that out tommorow

any way of setting the the gear change to hold off untill its passed a set speed ?

thanks for the help

paul

Reply to
paul moloney

On or around Thu, 25 Dec 2003 20:01:05 -0000, "paul moloney" enlightened us thusly:

if it's only slightly high I'd not bother. If it's more than say 1/4" over the "high" mark, you might want to let a bit out.

only by either of a) hold it in 3rd until you want top or b) keep yer toe down :-)

but the real solution lies in finding out why the engine's rough at circa

1800 revs. could be a carb thing, or an iffy injector or something if 'tis an injection one.

I've had related problems with mine in the 110 on LPG - get the tuning wrong an it's got no power at about 1800 revs, so when the box locks up, it loses speed.

The other thing you can do is to check/tweak the throttle and kickdown cable adjustment:

1). have an assistant (or a stick) floor the throttle pedal (engine off...:-)) 2). check that the throttles on the carbs (or on the plenum for an injection one) are indeed fully open, or nearly so. If necessary check and adjust the throttle cable free play with foot off - there should be enough free play that the cable is slack. any more is unnecessary and may lose you travel. 3). locate the kickdown cable which comes off the front near (lefthand-facing-forward) side of the box and goes up to a linkage which also has the throttle cable attached. 4). on top end of the cable outer is an adjuster, and on the cable itself there should be a little metal collar. The "correct" adjustment is that this collar, with the throttle pedal released, should be 1-1.5mm from the adjuster. 5). now floor the throttle again, using your hand. You should feel a "step" in the movement about 1/2" or so from the floor. This is the full-blown kickdown mode actuator in the box. If you pull the kickdown cable by hand, you can feel this - the cable comes out smoothly, then appears to stop, pull slightly more and it goes clunk inside the box and comes out about another half inch. have an assistant floor the throttle, and hold it down - check the kickdown cable by hand - you should be able to pull it slightly more than the linkage has - it's important that the cable doesn't get pulled to its absolute limit by the throttle linkage, as this can damage the bit inside the box, and you don't want the hassle of changing the cable, believe me. 6). if the kickdown cable isn't pulling fully, you can tighten it slightly, making sure that you don't exceed the limit as above. If you tighten the cable, all upshifts except for off-throttle will occur at higher revs.

The box, roughly speaking, has 5 modes of operation: off-throttle, light throttle, half throttle, full throttle, full + kickdown; although these are not really distinct bands as such.

off-throttle is where you put it in D on a downslope, and let it roll. upshift points are something like about 4 mph, 18 mph, 30 mph. light throttle is accelerating on the flat with just a tad of throttle, and gives very near the same speeds.

half-throttle will give you upshifts at about 10, 35, 45-50.

full throttle requires a nice touch on the pedal, to detect that kickdown point I mentioned: upshifts at about 15, 50, 75 I think.

kickdown is pedal-to-the-metal. upshifts at about 30, 60, and I've never done the 3rd-4th one...

there are some nice test routines in the book... for example - test 2nd-gear kickdown: drive the vehicle at 50 mph and floor the throttle, it should change down to 2nd. 3rd gear kickdown test is, I think, similar at 80 or

85...

other niceties: check 1st gear over-ride - drive at 40 mph+, engage lever position 1 with the gear selector, back off throttle and it should downshift at just over 30. Don't do that on slippery going...

some of the shifts really want a rev counter - for example, 3-4 on light throttle produces a drop in revs of about 200 rpm, which is almost undetectable. engage DDC at 50 or so drops revs at lightish throttle by about 300.

Reply to
Austin Shackles

It'll be the M4 past Slough.

Reply to
QrizB

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