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Drive train backlash ??
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DiscoMad
 


Member Since: 11 Jan 2005
Location: Warwickshire, United Kingdom
Posts: 190

Drive train backlash ??

My Auto TDV6 D3 has an annoying feature. When I drive along at 20-30 mph, sometimes more, with foot off the gas (to preserve the fuel economy !) on re-applying power, there is often a jerk, sometimes a thud, as something in the drivetrain takes up the power. Doesnt always happen, but it is repeatable. When I mentioned it to the garage, they tried another D3 and said that was the same ???

Does yours do this? Any ideas why this happens ? It is a real pain in slow moving traffic (say in a motorway queue).

Power delivery isnt that smooth either ! I must have an almighty turbo lag because putting my foot down at 50-60mph is greeted with an increase in revs and a noticiable delay before the power hits !

thx
  
Post #220877th Oct 2005 12:18 pm
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BN
 


Member Since: 18 Mar 2005
Location: Here
Posts: 6463

England 
Re: Drive chain backlash ??

DiscoMad wrote:
My Auto TDV6 D3 has an annoying feature. When I drive along at 20-30 mph, sometimes more, with foot off the gas (to preserve the fuel economy !) on re-applying power, there is often a jerk, sometimes a thud, as something in the drivechain takes up the power. Doesnt always happen, but it is repeatable. When I mentioned it to the garage, they tried another D3 and said that was the same ???

Does yours do this? Any ideas why this happens ? It is a real pain in slow moving traffic (say in a motorway queue).

Power delivery isnt that smooth either ! I must have an almighty turbo lag because putting my foot down at 50-60mph is greeted with an increase in revs and a noticiable delay before the power hits !

thx


Sounds like the fluid drive is either defective or on the way out. Should be silky smooth. Did you drive the dealers sample or just took their word for it?
  
Post #220957th Oct 2005 12:31 pm
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Coffeecup
 


Member Since: 15 Jul 2005
Location: Middleton, Manchester
Posts: 1084

England 2010 Discovery 4 3.0 SDV6 XS Auto Galway GreenDiscovery 4
Re: Drive chain backlash ??

DiscoMad wrote:


Power delivery isnt that smooth either ! I must have an almighty turbo lag because putting my foot down at 50-60mph is greeted with an increase in revs and a noticiable delay before the power hits !

thx


Isn't that a trait of Diesel Automatics.... You put your foot down, it kicks down, the revs go straight up, and then you find that it's reving in part of the range where there is no Grunt power.

Certainly that was exactly what was happening the other day when I was driving a Diesel Auto Freelander. I found I could accelerate away at 40-50 much quicker if I eased my foot down (and stopped the kick down) rather than floor it. In fact I did floor it once and the car slowed appreciably as a result of the kick-down and the lack of power at high revs.
 
Coffeecup

Tonga Green March 2005 TDV6 S - Tonga Green - Manual
Stornoway Grey May 2008 TDV6 SE - Stornoway Grey - Auto
Tonga Green Dec 2010 SDV6 XS - Galway Green - Auto 
 
Post #220987th Oct 2005 12:36 pm
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Dan
 


Member Since: 09 Aug 2005
Location: Oxfordshire
Posts: 96

United Kingdom 2006 Discovery 3 TDV6 S Auto Bonatti GreyDiscovery 3

I don't have this problem in my auto TDV6. As BN says it sounds like something is wrong. My auto is very smooth...
  
Post #220997th Oct 2005 1:11 pm
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arsi
 


Member Since: 01 Jun 2005
Location: Tampere
Posts: 77

Finland 2005 LR3 TDV6 SE Auto Zambezi SilverLR3

I have this also. It is noticeable only on second gear. Try using command shift to put it on second gear and slowly cruise on a flat surface. Take your foot off the gas pedal and then gently push it again. Sometimes there is a thud and only with second gear.

I have complained about this to my dealer and they said that it is OK to have some play in drive train. They also said that they tried their demo vehicle for comparison and it was the same.

My opinion is that there is an issue with this as I also can hear whining noise from the gearbox when accelerating. (This is also happening only when the gearbox is on second gear.)
  
Post #221017th Oct 2005 2:58 pm
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JAY
 


Member Since: 28 Sep 2005
Location: Herefordshire
Posts: 28

England 

I've got this problem!! I've found out that it's known as tip in / tip out clonk and LR are supposed to looking at a fix... Mine's been back to the factory and had a new rear diff fitted. (no change) Keep pushing as I'm getting fobbed off by the "they all do that" statement and all the other D3's I've driven don't...
  
Post #221037th Oct 2005 3:14 pm
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BN
 


Member Since: 18 Mar 2005
Location: Here
Posts: 6463

England 

Guys, you have a fluid flywheel problem I think, but this is not my area as I am a manual fan as you know. What ever you should not have that sort of problem. The first thing is the EPQR as they are hardly ever filled out by garages as it takes them too long. As a result LR do not get to hear of the faults.

The D3 auto LR lonaed me from Gaydon, certainly did not have any problems at all and drove like silk.

I am convinced that most of the problems are the middle men the dealers.
  
Post #221077th Oct 2005 4:32 pm
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arsi
 


Member Since: 01 Jun 2005
Location: Tampere
Posts: 77

Finland 2005 LR3 TDV6 SE Auto Zambezi SilverLR3

I have also noticed that when the engine (and transmission) is cold, during acceleration when the gears are shifting up, engine revs up like the gear has not been engaged. This happens only during the first kilometers in cold morgnins.

First time I mentiond about this to my dealer they suspected the flyid flywheel but after inspection and comparison to reference demo car they said it should be OK. (Between the lines I could read: drive before it breaks.)

My D3 is not my first car with auto gearbox and definitely the ones that I have had (Volvo/Chrysler) did not behave like this.

It seems that I need to talk with the dealer once more to have some actions ongoing.
  
Post #221217th Oct 2005 5:56 pm
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JAY
 


Member Since: 28 Sep 2005
Location: Herefordshire
Posts: 28

England 

I have an EPQR already raised which was what started the trail whereby the car has been back to the factory... The dealer was being guided by LR tech (who haven't got an answer yet). I too have had autos before and they didn't do this (nor indeed have other D3's I have tried). I'll raise the flywheeel issue with my dealer.. If this is not an isolated fault then it's no surprise the demo drove the same way.. compare something broken with something broken too and you'll see no difference.

keep me up to date with progress...
  
Post #221247th Oct 2005 6:23 pm
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DiscoMad
 


Member Since: 11 Jan 2005
Location: Warwickshire, United Kingdom
Posts: 190


Well Blow me Over ! Thud

Tip-in/tip-out problem or fluid flywheel ! great feedback and information Thanks.
The fault occurs at all times on my car.

My car is booked in for 2 days to investigate the cruise control and cold heater problems, so i will push for this to be investigated also .

Will keep you informed of my progress !
And just for interest, this is a replacement D3 delivered in May. The replaced D3 didnt have the TI-TO problem! Rolling with laughter
Russ
  
Post #221277th Oct 2005 6:41 pm
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BN
 


Member Since: 18 Mar 2005
Location: Here
Posts: 6463

England 

DiscoMad wrote:
Well Blow me Over ! Thud

Tip-in/tip-out problem or fluid flywheel ! great feedback and information Thanks.
The fault occurs at all times on my car.

My car is booked in for 2 days to investigate the cruise control and cold heater problems, so i will push for this to be investigated also .

Will keep you informed of my progress !
And just for interest, this is a replacement D3 delivered in May. The replaced D3 didnt have the TI-TO problem! Rolling with laughter
Russ


My vehicle had cruise control problems and after getting a bit tough with LRCS, they got a top techi out and it was found to the steering slip ring. It also messed up other systems, like the suspension which does not even relate, but it is now fixed. They also tried to tell me it was going to take 3 to 4 weeks, but after a little bit of 'discussion' it was resolved within 24 hours.
  
Post #221337th Oct 2005 7:15 pm
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DiscoMad
 


Member Since: 11 Jan 2005
Location: Warwickshire, United Kingdom
Posts: 190


Just done a search on the web and found several references to this on Ford SUVs and Cadillacs;

Quote:

This from Feb05 on a Cadillac forum;
NEW Firmware update 2004 V8 AWD

The thump/clunk that occurred between 18-27 mph, when I would let off the throttle for 3-4 seconds and then reapply the throttle (lightly even) is gone with new firmware. The engine used to drop in RPM to a very low level 600-800 rpm at 18-27 MPH , The dealer reprogrammed the transmission computer and now the RPM stays higher at 900-1200 RPM at 18-27 mph. Applying the throttle does NOT produce a thump/clunk any more. Throttle response appears to still be good.

I do not know if this prevented the transmission from going into a “neutral like state” or modified the torque converter algorithm (if it has an electric disconnect), or was just an rpm level fix, but most likely is a gear selection change i.e. downshifting through the gears etc. Nevertheless, problem was completely resolved.

The TSB is #1576962 for the ECM reflash. This will re-condition the engine calibration to keep a little bit of positive torque on the driveline. The clunk you're getting is a result of the total lash in the driveline (transmission, transfer case, and prop shafts). However, there's also a hardware change (low-lash transfer case) that also needs to be installed if your SRX was built before a certain date. That date is 5/14/04. Looking at the last six digits of your VIN, is it greater or less than 192515?

It is not especially loud, seems to come from under the car in the center but more towards the rear, and is always accompanied by a whiplash type motion where the car jerks forward or backward while accelerating after slowing, like you would do in stop and go traffic. I have never noticed it while going at moderate or high speeds. It is best felt and heard by the driver, but my car now has considerably worsened and is noticed in any seat.

New flash prevents throttle shut down when letting off gas. As rpm's drop when letting off gas as original program allowed the rpm's jump by 200 rpm's with the foot off the gas then drops slowly. Keeps that positive torque on the drivetrain to the extent that prior to stopping the tranny downshifts like under load (which it is with the brakes applied)going up a hill.

So the reflash causes the RPM's to be maintained when the throttle is released? That would be like keeping your foot on the gas

Imagine pulling a child' s wagon with a 3 foot rope with one end tied to the wagon handle and the other in your hand. If you are pulling at 3 mph and reduce your walking speed to 1 mph the wagon will coast and close the gap between you and it with the wagon handle and rope dropping to the ground.
If you resume your 3 mph walking speed abruptly the slack of the rope will be eliminated and in the meantime the wagon has slowed so there will be a jerk on the wagon as the slack (drivetrain lash) is taken up by the forward motion resuming.
However if you start slowing down but keep the rope taunt just barely out pacing the slowing wagon as it coasts; when you resume speed there is no slack to absorb.


Positive torque is still released from the driveline when you go to 0% throttle under the new cal. The difference is when you tip back in, the vehicle knows to ignore your actual TPS% input and ramp up at a slower rate instead (throttle by wire enables this technology). We're only talking about a fraction of a second delay so there should be VERY little or no loss of throttle response.


The techincal service doc
http://www.cadillacfaq.com/stsfaq/tsb/data/tsb/04-07-30-044.pdf



And here is a link to a 56 page research thesis on this problem !

http://www.s2.chalmers.se/research/control...ansson.pdf
  
Post #221347th Oct 2005 7:16 pm
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lee01277
 


Member Since: 06 May 2005
Location: Shed
Posts: 821

United Kingdom 2005 Discovery 3 TDV6 S Auto Zambezi SilverDiscovery 3

dd_156ar wrote:
I don't have this problem in my auto TDV6. As BN says it sounds like something is wrong. My auto is very smooth...


dito
 ..............Somewhere in-between my old D3 and what's to come next .........  
Post #221807th Oct 2005 11:01 pm
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JAY
 


Member Since: 28 Sep 2005
Location: Herefordshire
Posts: 28

England 

Had an independent engineer view my car today. He agrees there is a problem with the gearbox.

A general question to other auto box users is at what speed does drive disengage in your cars? Specifically when you are coming to a halt with foot off the throttle keep an eye on the rev counter and see at what road speed the needle drops to idle. I ask as in my car this occurs from around 15 - 20mph, in effect it is then freewheeling as I have no drive engaged and thus no engine breaking. Once I'm at or near rest of course the crawler comes into play and drive is restored. My concern is that from 15mph -20mph downwards I am relying on brakes alone to stop (not good in the recent ice) and I wanted to see if I am the only person with this condition.
  
Post #2932323rd Nov 2005 6:02 pm
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chvdw
 


Member Since: 15 Oct 2007
Location: Zuid Holland
Posts: 30

Netherlands 2005 Discovery 3 TDV6 HSE Auto Zambezi SilverDiscovery 3

I know this is an old post, but was there a solution found for this?

I seem to be having a simular problem. When slowing down, but not coming to a complete stop (stays in 2nd gear), when re-applying the power there is a thud. It feels like there is a slack in the drive train, but only apparent in 2nd gear as it seems.
  
Post #23400214th Dec 2007 10:15 am
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