picking your brains guys,,

[PSH]

Morning all

I have had an issue on the car for some time now that in recent months has been getting worse and I'm stumped as to which of a number of things that it could be. The symptom is basically a very rough ride which is very dependent on the road surface. A perfectly flat new road and it's hardly noticeable if at all, add a slight worsening of the surface and the car feels like it's going over tiny cobble stones, the worse the surface the worse the effect. At times this feels too bad to drive and has me a little paranoid about the possible causes. I have ruled out any engine issues, the feeling is there just the same with the car rolling at any speed with either the clutch engaged or the transmission put in neutral. I have considered rear wheel bearings and torque tube bearings, not because I think it's these, as I said there are no related sounds but purely for the fact that these parts are still original on a chassis that's done over 200k miles. These days I'm not in a position to just say...'right let's change the lot' those days are long gone. About two years ago I had thought that there may have been a slight wheel bearing sound on the rear left but this quickly disappeared so ruled this out. Everything that I have read on the web re wheel bearings and torque tube bearings on 944's states the noises associated with failure, I haven't found anything to say these items have failed with no noise. A few months ago while my son had the car on the ramp I did ask him to check the rear bearings due to this rough feeling, a bit like a rumble but again no sound and no feeling through the steering, he could feel no play or any sound while checking said bearings. Alas, I didn't ask him to take a look at the torque tube, I'll try to address that asap. Now my paranoia is making me think that I should stop using the car until I can get this sorted, I do not need a catastrophic disaster from a wheel or tube bearing. There is another possibility, well probably more hence why I'm seeking other opinions but it could also be the tyres (this is my son's view), the front right has worn unevenly badly due to me taking so long to get the geometry sorted after the rebuild, the reason that I'm not convince it's the tyres is the ride feels far too rough, more so than anything that I've experienced before
Everything that I have read on the web re wheel bearings and torque tube bearings on 944's states the noises associated with failure, I haven't found anything to say these items have failed with no noise. A few months ago while my son had the car on the ramp I did ask him to check the rear bearings due to this rough feeling, a bit like a rumble but again no sound and no feeling through the steering, he could feel no play or any sound while checking said bearings. Alas, I didn't ask him to take a look at the torque tube, I'll try to address that asap. Now my paranoia is making me think that I should stop using the car until I can get this sorted, I do not need a catastrophic disaster from a wheel or tube bearing. There is another possibility, well probably more hence why I'm seeking other opinions but it could also be the tyres (this is my son's view), the front right has worn unevenly badly due to me taking so long to get the geometry sorted after the rebuild, the reason that I'm not convinced it's the tyres is the ride feels far too rough, more so than anything that I've experienced before and I'm getting zero feedback through the steering wheel?
Due to this if I was going to take a guess as to what part of the car it's coming from I would have to chose the rear just because I'm getting nothing through the steering but the feeling felt does not seem to be coming from any one part of the chassis, it's the whole car...if that makes sense? This could and most probably is saying 'it's the tyre's but I don't want to spend money on something that I'm not sure about...so guy's, what do you think, is it one of the parts I've suggested or something else, perhaps related to the suspension?

Look forward to reading your views

Pete

 

[blade7]

If the tyre is worn change it Pete, I'm tight but I don't take chances with tyres. If it's not that ask your son to sit in the back while you drive, if necessary take the rear seat base out to try and pinpoint the noise ?

 

[PSH]

good idea Paul although he's a very busy chap these days.. the tyre is worn, yes... and will be changed, it's still legal but does need sorting, the question now is, is the issue the tyres alone.... alas I sold my spare set of wheels a long time ago... that might have been a silly move...lol

 

[blade7]

Years ago when the fronts got down to 3mm on the front of my Cosworth it used to follow every imperfection on the road. More recently the rears on my 944 had plenty of tread, but were 8 and 9 years old, the newer one would let go unexpectedly at the limit. In the extreme think what flat spotting F1 tyres does. Good luck sorting it out.

 

[PSH]

Thanks Paul, the tyres are a suspect and to be honest are what I'm hoping is the problem as they would be both easier and cheaper to sort. Tyres are now two years old, I have one of the fronts that's uneven as stated but this has been the case for over a year with nothing like the feeling through the chassis displayed now. I tried changing pressures yesterday but to no avail..

cheers

Pete

 

[Dan944t]

hi Pete,

this does sound wheel related as if the torque tube bearings where shot you would think that you'd hear the and feel the same rumble over all road surfaces?

have you been over any pot holes or harsh bumps ect lately?

if your son does tyres I would get him to put each tyre on the balancing machine just to rule that out. That would show up if you've dinged a wheel or two and are running untrue which when in machanics years ago have experienced before rumbles and after balancing all for wheels the rumble went away. It was I van which had this symptom and had steel rims but the principle is the same, the guy hit a few holes in the road and it created the van to rumble very load and balancing them and taping out the rim where it dented sorted the van out once again.

Its a a guessing game at the minute but this is probably your cheapest option and would rule that out for starters with not too much effort .


Also get the front wheel bearing play checked I know I've re greased mine before and tightened when they both came a bit loose, although they didn't chase a rumble they as blade said above would bloody follow all imperfections in the road and I figured it out to be these slightly loose and beeded a little more bearing grease in there.

hope you Sort it soon.

Ps I'm still waiting for my short block and head/rods/Iasa pistons to come back from John! I'm absolutely dying to rebuild my engine now and gonna have to read through your blog to remember where a few things go now I recon?? But I recon it will be ok once I get set out ...... when ever that day may be ( I miss her )

all the best
Daniel

 

[PSH]

Hi Daniel

Thanks for the advice, now, asking my son to check balance on all 4 wheels sounds like a great place to start, pot holes are the bane of our lives, I have hit a few over the years but can't say that I've noticed a change in the car after, but yes i have hit them and at times hard so will look into this. If I can get him to remove all 4 wheels to do while on the ramp I could take a good look under the car and check the bearings...I don't think that anything is lose though, I don't have any handling issues not that I push the car that way anyway and no feedback through the steering to suggest something hanging off. this has been a puzzle, I know this car inside out but this is new. As stated elsewhere the engine is fine, I can redline it on the drive and there isn't a hint of a rumble, it's totally smooth which is a little reassuring.. out of balance tyres would indeed be the best outcome for me.

Hope you get your engine back soon, good to hear you've going IASA pistons, these are great pistons which greatly reduce friction in the engine, you'll find the engine rev up much quicker because of them, they can also hold a lot more boost with the extra ring. i had originally planned to machine small semi-circles in the top ring groove to hold extra boost, something that I've done on my son's Cossie but saw no need when looking at these pistons. you'll probably be the only other 951 in the country with such pistons.. they are a secret weapon, one among many in my engine, one of the others being the Raceware bolts which probably saved me over the weekend when the engine hit over 7k revs....

Pete

 

[Eldavo]

I had a similar issue in my old 2.7 - turned out that a D90 wheel had a slight flat spot.

£50 later and it was round again and balanced - sorted.

 

[PSH]

I had a similar issue in my old 2.7 - turned out that a D90 wheel had a slight flat spot.

£50 later and it was round again and balanced - sorted.

Thank you, this is most reassuring...

cheers

Pete

 

[Dan944t]

Hi Daniel

Thanks for the advice, now, asking my son to check balance on all 4 wheels sounds like a great place to start, pot holes are the bane of our lives, I have hit a few over the years but can't say that I've noticed a change in the car after, but yes i have hit them and at times hard so will look into this. If I can get him to remove all 4 wheels to do while on the ramp I could take a good look under the car and check the bearings...I don't think that anything is lose though, I don't have any handling issues not that I push the car that way anyway and no feedback through the steering to suggest something hanging off. this has been a puzzle, I know this car inside out but this is new. As stated elsewhere the engine is fine, I can redline it on the drive and there isn't a hint of a rumble, it's totally smooth which is a little reassuring.. out of balance tyres would indeed be the best outcome for me.

Hope you get your engine back soon, good to hear you've going IASA pistons, these are great pistons which greatly reduce friction in the engine, you'll find the engine rev up much quicker because of them, they can also hold a lot more boost with the extra ring. i had originally planned to machine small semi-circles in the top ring groove to hold extra boost, something that I've done on my son's Cossie but saw no need when looking at these pistons. you'll probably be the only other 951 in the country with such pistons.. they are a secret weapon, one among many in my engine, one of the others being the Raceware bolts which probably saved me over the weekend when the engine hit over 7k revs....

Pete

Hi pete,

i think we also went for raceware studs can't remember? I'm also a ginniepig for the first 944 turbo racing conrods to be made bespoke through John at serdi giving a company he met in millan my conrods to copy and John says they are very nice and a little lighter than standards , as I had different numbers caps we both thought best not risk it.
i also becuase of you bought a crank scraper which I'm really really looking forward to feeling any differ in spool up along with slightly reduced flywheel rweight reduction by john just to give a little edge hopefully, but probably looking at rebuilding in the winter now what with the new house and baby here !

I really hope the rumble turns out to be something simple like your tyres.

Once you do do get it to your sons inspect the rims also for dings on inside where you can't see.

Also I know it sounds stupid but inspect disc and calliper tightnesses for any abnormality or movement.

I once had had a small stone flick up and get wedged between disc and calliper and I kid you not I thought my wishbone dragging on the floor, even people were staring as I pulled off motorway and into the closest pub carpark. Some things are little but sound absolutely horrendous espeacially in the cabin.

Hope you find your problem soon!

 

[PSH]

Cheers Daniel... just spoken to my son, he's away on holiday just now, he will check the wheels and bearings as soon as he can when back. The crankscraper won't affect spool but will greatly affect how quick the engine revs up, this combined with the full race pistons, your new rods and flywheel reduction all adds up to a much more lively engine, much more fun than a larger capacity engine, IMHO of course. For spool you need a better turbo than the KKK, I can't remember what you have?... a good EBC can also help with spool if set to a high 'duty cycle'.. this is ok but best have a stand alone boost gauge with audible warning......mine was going mad the other day when playing with that new RS3 Sportback... I learned something... my car is some what faster... I didn't try to overtake him, I didn't need to.. just paced to see where we were for comparison... I have since looked up the spec for this new Audi as he wasn't hanging around... 362bhp, 480nm torque, 4WD 2.5ltr turbo... 0-60 of 4.1, max out at 155 or 174 with no restrictor.... a good competitor but slower than my own car... Now during this exercise I hit over 7k by mistake, bad gear change, I am so glad that I don't have standard rod bolts fitted as it could have destroyed the engine. This got my curiosity up and so I entered my transmission/rpm figures into 'gearcalc' to see what speed this would max out at..... just over 186 MPH......yes i can live with that...

Pete

 

[Dan944t]

When you talk your car It always makes me miss mine so much [] I have a stand alone boost gauge but want to get the same as yours so I can set a buzz instead of having to look. I have the standard kkk my cars 87 turbo and I do love the spool with the new mods I fitted before idiots joy tested my car and boosted it to 26 psi withought my permission and cracked a cylinder! :-( I have 55 injectors, upgraded mortorsport fuel pump, tail 38 dual port wast gate, larger intercooler, 993 recirculating valve /dump valve, uprated boost pipes with pushfit conections, sports backbox, heat wrapped header downpipes/turbo downpipe, manual boost controller, stage 2 jmg chipset, readjusted standard afm to work with mods. + all the new stuff to go on for when I rebuild the engine back up, so I'm excited becuase it felt like a rocket with all these mods so would like to think I'll pio up more torque with the scrapper, pistons, rods and lighter flywheel .......... one day soon I'll find out ....

 

[PSH]

looks good.... 26psi....yikes?.. mind you one of my sons is always pulling my leg that his cossie held 35 psi.. mad Ford drivers... you have a good list there, one thing that I would comment on is using a heat wrap around the inlet manifold, I had planned to do the same myself, in fact I had completed wrapping both sections when my eldest son popped over and said get rid or I'll end up cracking the pipes, I followed his advice and ditched the wrapper. I have since read accounts on various forums where people have destroyed their manifolds due to wrapping so beware, I'm not saying that it will happen, but why take the chance? You will have a very fast car when done....
You will have a very fast car when finished and one with a strong bottom end.. all good for boosted engines...

 

[Dan944t]

Thanks Pete,
hope so mate to be honest I was very happy with all those mods before they ruined it , and it took me best part of 7 months on my back after work every night as I rebuilt top end at same time so hadn't even run it in at all!

sorry I meant I wrapped outlet/downp not inlet manifold, I've actually sprayed that with vht red.(that's was also your
Fault when I saw your red shirt block )
daniel

 

[PSH]

Thanks Pete,
hope so mate to be honest I was very happy with all those mods before they ruined it , and it took me best part of 7 months on my back after work every night as I rebuilt top end at same time so hadn't even run it in at all!

sorry I meant I wrapped outlet/downp not inlet manifold, I've actually sprayed that with vht red.(that's was also your
Fault when I saw your red shirt block )
daniel

Yes, it was the exhaust manifold that I was referring too... some have had no issues, others have....like most things in life it's down to personal choice and I guess luck of the draw.. my boy said don't use it and I trust his opinion....he hasn't let me down yet..

Pete

 

[Dan944t]

I see so the downpipe are a bad idea to wrap?

i did research and I also saw it had mixed views such as oil soaking in and why don't f1 cars use heat wraps ect, but I spoke to a guy that wraps Tvr downpi and to be honest it was him that changed my mind and so I bought a load from him.

I know now what your saying though ??

Its ta one of those debatable ones

Daniel

 

[bmnelsc]

No mention of shocks or struts in this discussion. Are they newish/tested and proved good? Worn struts/shocks can produce a rumbling noise along with poor ride. My S2 had a "dead spot" in one front strut - about 2 inches of effortless movement once the spring was off - I don't know if it "pumped up" after a little driving or stayed soft. It wasn't particularly noisy (rumbling) but very poor ride over rough surfaces (I used to describe one of our arterial roads as a rally stage - fortunately now resurfaced). My Potenza RE050A Pole Position tires also masked suspension noise as they are firm and thump pretty good over road imperfections so the ride is noisy even if not harsh. I didn't find this problem until the struts were dismantled as the springs kind of hid the problem when doing static bounce tests, etc. on the driveway. Also, noises coming from wheels/suspension can be hard to locate as their noise "telegraphs" through the body pretty well. Really need a passenger who can move around to really focus on the source of the noise.

 

[PSH]

Hi Bruce

I have no noise, I did ask my wife if she could work out where the rumbling/vibration was coming from but it's not coming from any one spot, it's the whole car...I have taken on board what Paul and Daniel have said and leaning towards this being wheel/tyre related rather than anything serious. This is in fact what my son has been trying to persuade me as to what's the most likely cause. I need to use the car again for my daughter's wedding next weekend which is before my son is back from hols, well he's back that day so no chance of doing the wheels. I will reduce the pressure in the tyres for this and hopefully it won't be too harsh, I don't have too far to go. once the car is on the ramp I'll have a good check of all suspension components, I'll also check the torque tube bearings and wheel bearings.

cheers

Pete

 

[944Scott]

This maybe not what's causing your problems but I wouldn't be surprised if your torque tube bearing weren't shot at 200k. I changed a wheel bearing because I had a rumbling noise that sounded like it was coming from over my left shoulder. Once done the car was noticeably quieter but replacing the bearing unmasked another rumbling (quieter and more central) I had also been experiencing a vibration when lifting off at speed (coming from between the seats) I've not driven the car since replacing it as its still on axle stands but when I removed the old tube (165k on mine) and did a comparison side by side with the new one it was making a noticeable grumbling noise.

 

[PSH]

Thanks, Scott, I don't think that it is the torque tube but haven't ruled anything out yet...I have no noises that are unusual to the car, I would expect noise from a worn bearing...at some point I know that I will need to renew both tube and rear wheel bearings, they are one of the few pieces of original service parts still on the car. I have the usual chatter when depressing the clutch but the transmission has always had this and it's a lot quieter than some that I've heard.

Pete