986 rear end shuffle

[acgtrider]

Hi folks

trying to find the source of the rear end wobble over bumps on my dads 986 with 130K miles.

It is most noticeable over small grooves and strips in the road. It feels as though the rear end shuffles side to side.

The car has fresh genuine Porsche arms all round with exception of the rear tuning forks which are original. New engine mount bushing and low mileage gearbox bushings. Alignment was done recently at the main dealer after the arms were fitted.
 

I am thinking the car is due a rear strut replacement although there are no signs of leaks. Fronts we’re done 40k ago and feel great.

Any help would be much appreciated as it’s reducing his enjoyment of the car.

Cheers

[Menoporsche]

Hmm.  Usually this is a classic symptom of engine mount IIRC.

[½cwt]

Is there any knocking of any sort when driving over bumps?  It should be silent if everything is sound.  I did all mine except rear tuning forks back in late 2020, but it was only when I did the tuning forks at the rear in mid 2021 that all the suspension knocks and creaks went away.  I'd also possibly go with dampers, if you are getting uneven damping because one is offering less damping than the other that might feel the way you describe.  Also if the front was done relatively that long ago it would be time to sort the rear anyway. 

(Wow, OE Porsche arms - that was a big bill!)

[greenman986s]

How old are the tyres?

[acgtrider]

Hi folks

Yea the previous owner of 16 years kept up a full OPC history and all works were carried out by them.

the tyres are pirelli with a date code of mid 2020.

there are not really any clunks. I have replaced the rear tuning forks on my last 3 Boxster’s due to the snooker ball rattle. I wonder what effect they have on the ride/ handling as it’s a monoball joint. 
 

cheers

[Nobbie]

At 130k, I think the struts are likely to be pretty shot if mine were anything to go by when I replaced at 140k. There were no leaks visible on them, but they had lost most of their damping ability. I never noticed anything going over bumps, but I was new to the car so didn’t know what to expect. The effect I did notice was a floaty feel when driving along fast slightly undulating A roads as the undulations weren’t being damped out effectively. Probably would have affected the sort of issues you describe.

[phazed]

I will definitely question tyres.

I have had with several cars over the years, as the tread gets down to the last few millimetres, the car tramlines and follows imperfections and repairs in the road.

[acgtrider]

4 hours ago, Nobbie said:

At 130k, I think the struts are likely to be pretty shot if mine were anything to go by when I replaced at 140k. There were no leaks visible on them, but they had lost most of their damping ability. I never noticed anything going over bumps, but I was new to the car so didn’t know what to expect. The effect I did notice was a floaty feel when driving along fast slightly undulating A roads as the undulations weren’t being damped out effectively. Probably would have affected the sort of issues you describe.

Hi 

 

Thanks for the reply. That is exactly my thinking, on all my previous cars the dampers have been shot long before 130K so i don't know why i am telling my self the boxster is any different.

Looks like a pair of rear shocks is on the cards then.

 

Cheers

[acgtrider]

26 minutes ago, phazed said:

I will definitely question tyres.

I have had with several cars over the years, as the tread gets down to the last few millimetres, the car tramlines and follows imperfections and repairs in the road.

Hi 

 

Tyres are 2020 pirelli P zero with over 6MM of tread, while not my favoured tyre they are ok. so i am pretty certain its not the tyres. Its not really a tram lining issue but more of a rear end movement/rebound damping issue id say.

[EXY]

9 hours ago, greenman986s said:

How old are the tyres?

 

4 hours ago, phazed said:

I will definitely question tyres.

Might still be worth asking/borrowing a set of wheels just to rule them out.

I'm sure if you ask someone on here will lend you a pair of suitable wheels/tyres for a comparison drive just to rule it out.

I was of the same thinking as Meno in the second post with the engine mount. Did you replace the spacers either side of the front mount?

Edit;

Just thinking, perhaps it would be worthwhile asking Centre Gravity for their take, they come highly recommended. 

https://centergravity.co.uk/

Edited November 5, 2023 by EXY

[acgtrider]

20 minutes ago, EXY said:

 

Might still be worth asking/borrowing a set of wheels just to rule them out.

I'm sure if you ask someone on here will lend you a pair of suitable wheels/tyres for a comparison drive just to rule it out.

I was of the same thinking as Meno in the second post with the engine mount. Did you replace the spacers either side of the front mount?

Edit;

Just thinking, perhaps it would be worthwhile asking Centre Gravity for their take, they come highly recommended. 

https://centergravity.co.uk/

Yea ! I’ll try on the Carrera classics off out other boxster to be sure. 
 

I was also hoping it was the engine mount but the new bushing has not cured it.

I have had this on another boxster but sold it prior to delving into shock replacement.

I live up in the north east of Scotland so decent indi garages are hard to come by. I also do all my own spannering haha.

thsnks for the help so far guys.

Cheers

[bally4563]

My thoughts instantly was alignment 

[Menoporsche]

If your engine mount has been done, then yes, shocks with 130k on them look a likely target.  And frankly you won't go wrong refreshing them anyway.

[Danncus]

Geometry. 

[acgtrider]

Hi guys 

it Is a possibility that the Geo could be out but I’m not so sure. I’m also a bit apprehensive about spending the 100 plus quid for it to still be out and then need doing again after struts If it turns out to be that. Saying that it might be worth having it checked for peace of mind. 
 

Cheers

[½cwt]

@acgtrider has the problem developed after the new arms were fitted?  If so the geo could have moved if the bolts were not torqued correctly.  It is very difficult to apply the correct torque when the car is on a ramp with wheels on, i.e. the condition in which you have to do the geometry.  I always recheck the torque on mine after rear geo by popping it on axle stands, removing the wheels then lifting the hub to the equivalent resting position (Z=0), then apply the torque to the toe and camber bolts.  I know not everyone has this facility.

Edited November 6, 2023 by ½cwt

[½cwt]

4 minutes ago, acgtrider said:

Hi guys 

it Is a possibility that the Geo could be out but I’m not so sure. I’m also a bit apprehensive about spending the 100 plus quid for it to still be out and then need doing again after struts If it turns out to be that. Saying that it might be worth having it checked for peace of mind. 
 

Cheers

Just go to a Kwik fit or somewhere similar to get it on a Hunter system, that will give you the current settings.  Most of these places only charge if they get the spanners out, so no cost if the geo is OK.  If it is out you can see by how much, but still decline the work.

[acgtrider]

1 hour ago, ½cwt said:

@acgtrider has the problem developed after the new arms were fitted?  If so the geo could have moved if the bolts were not torqued correctly.  It is very difficult to apply the correct torque when the car is on a ramp with wheels on, i.e. the condition in which you have to do the geometry.  I always recheck the torque on mine after rear geo by popping it on axle stands, removing the wheels then lifting the hub to the equivalent resting position (Z=0), then apply the torque to the toe and camber bolts.  I know not everyone has this facility.

Hi 

The arms were fitted by the main dealer 12 months prior to my ownership. The previous owner said she had never felt the issue present. To be fair I am obsessed with trying to iron out all issues on my cars so I am always honed in on how they feel. This having been my fourth it’s interesting comparing them especially to our other 986. I have read of people having issues with incorrect torque on bolts so I will check them on the ramp. Great shout on trying quickfit or similar. I will get that done ASAP. Cheers

[acgtrider]

Had the car out on a 100 mile round trip on some great roads yesterday. The car felt great for the most part.

I didn’t notice the issue present as much at higher speeds but it’s really noticible at lower speeds where the surfaces are poor such as entering small villages and towns. It is a certain type of road imperfection/rut that causes it to get upset.

 

The rear shocks also happen to have a light hissing/squelch noise present when the roof is up. Can’t remember my other ones doing this but I could be wrong as some dampers are noisier than others.
 

cheers

Andrew

[bally4563]

2 hours ago, acgtrider said:

Had the car out on a 100 mile round trip on some great roads yesterday. The car felt great for the most part.

I didn’t notice the issue present as much at higher speeds but it’s really noticible at lower speeds where the surfaces are poor such as entering small villages and towns. It is a certain type of road imperfection/rut that causes it to get upset.

 

The rear shocks also happen to have a light hissing/squelch noise present when the roof is up. Can’t remember my other ones doing this but I could be wrong as some dampers are noisier than others.
 

cheers

Andrew

A floating sensation/wandering sounds to the thrust angle is out, I had this once where there was too much toe out on the front and it was terrible to drive, shocks just don’t go overnight they gradually decline and if it’s a car that is in regular use , it’s a question you would notice , until you jumped into one that had a suspension refresh, just my  tenpenneth worth! 

[bally4563]

Find a stretch of road with a bad camber , let go of the wheel and see if it quickly turns into it, that will give you a guide on your alignment, it should slowly drift and not immediately 

[bally4563]

3 minutes ago, bally4563 said:

Find a stretch of road with a bad camber , let go of the wheel and see if it quickly turns into it, that will give you a guide on your alignment, it should slowly drift and not immediately 

Oh ! And not at 70 mph!! 20 to 30 will be sufficient 

[RedBarediver]

I had the same in my 2.5. It gave a sort of a little wiggle if you hit a small bump in the road when you're going around a corner. Didn't do it when you hit a bump going straight. Turned out the right rear shock was kaput. Replaced it with a second hand one from Steve Strange and all good. 

I plan to have the rear suspension refreshed by Paul Lewis (Torque Boxster) sometime soon, after he did such a great job on the front suspension.

[acgtrider]

1 hour ago, bally4563 said:

Find a stretch of road with a bad camber , let go of the wheel and see if it quickly turns into it, that will give you a guide on your alignment, it should slowly drift and not immediately 

I must say the alignment feels good to me. I have driven many cars with the alignment way out after I have done suspension work and know the feeling you mean. I’ll try it again anyway to see ! Cheers

[bally4563]

10 minutes ago, acgtrider said:

I must say the alignment feels good to me. I have driven many cars with the alignment way out after I have done suspension work and know the feeling you mean. I’ll try it again anyway to see ! Cheers

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