picking your brains guys,,

[Dan944t]

Not sure why Pete , but your car situation doesn't leave my mind and feels like it's bugging me as if it's my own.... and I'm someone whos never even got time to have lunch at work!

Heres what hat gut feeling is... I think and hope it is the tyres? But ... if it's not then my thoughts are bearings, ie wheels (rear ? ) Or torque tube bearings?

i hope not the torque tube.

something tells me it's something that is in motion from what your saying as under heavy load it's better or goes away would suggest bearings of some type. I've had a bad rumble in my non asperated 944 20 years ago that ended up being the rear wheel bearing which I changed both with sway bars off for them to go on the press. That particular load rumble I remember was awful but was noticibly from the rear of the cabin.

the ideal way would be to test the torque tube to put it in drive on a ramp and determin the rumble is coming from the tube but the thought if this I wouldn't advise for safety reasons! It's a shame there no easy way to stop the torque tube from spinning as your driving.

Just had a idea not sure if you could get it through but you would see in the car before you try?

right, maybe to determin the torque tube bearing you could take off both gear gators so you just have the mental part of the gear leaver coming up. Take all the sound deadening foam from around the hole that the gear leaver comes up into the cabin so that you have a clear view of the torque tube.

Now see if you can get a long thin flat head screwdriver or bar, in there touching the torque tube, and select a gear that gives the best clearence to do so. And if this is possible get someone to go for a drive with you on motorway in fith gear maybe so linkige is out the way, and get them to put the screwdriver on the torque tube when it's rumbling and put the handle to the ear and if it's the torque tube bearings then you shoukd hear this through the tube and into the screw driver!?

atb
daniel ??

 

[PSH]

Sounds like you've lost nearly as much sleep as I over this Daniel... I find myself constantly monitoring the car...drove back this afternoon trying to work out what exactly is going on? at one point I hit a fresh patch of motorway and it was like heaven, I tried changing speed to see if I could replicate the rumble under load or deceleration but nothing?....just a blissful feel to the drive. I'm still struggling with the possibility that this can only be the tyres though. I think it's how rough it feels when taking up drive quickly when turning, say out of a side road that points me towards CV's or gearbox mount, the fact that both of these are probably overdue renewing anyway adds weight to this idea.
I hope that my son can find time in his busy garage to get the car on the ramp this week, it would be nice as Saturday I'm off out on another one of my loves to go and see my favourite steam locomotive 'Flying Scotsman' at Didcot Railway, I'm looking forward to it and the car has to go too.....I wouldn't want it feeling jealous...

Pete

 

[944Scott]

Could you put a mechanics stethoscope on the torque tube with the car jacked up and the wheels turning?

 

[PSH]

Good afternoon guys, thanks to my son finding time for me on a weekend (he's flat out most days) I have an update on the car although not fully roadtested yet but so far things seem good. Now the tyres were clearly an issue and I'm somewhat disgusted by the quality or lack off of the old Bridgestone SO2's as these were not old at two years on the car and 3 years from manufacture. Rest assured I won't be using this brand again, my son can now rightly brag...'I told you so'...lol
Here's a picture of one of the rears, this rubber is rock hard, has hard spots around the tyre that has caused uneven wear, if you run the flat of your hand around the center of the tyre you can feel the bumps/hard spots, best way to describe it is like flat spots on a race car although opposite if you get my meaning? Added to this in the first photo shown you can see the compound breaking down between the tread, not good, not good at all.

So what tyre have I chosen? I had a number of criteria for what I felt my car needed, low sound (67db) , good in the wet (A rated), high-speed (Y= 186mph), rim protect and price in that order. The tyres I chose are the Dunlop Sport SP Maxx RT, the reviews from both official testing and customers is very good, superb in the wet, low road noise and good handling. Add the shorter high-speed braking distance when compared to others at this level (IIRC 3.5meters) and a compound made from motor-racing experience then that was good enough for me, oh and very good aquaplaning performance.
here's the front tyre fitted

And here's a view of the asymmetric tread..

I've read that these give a performance not far behind slicks, they are of course 'summer tyres' I ask myself what old bill wmay say when they wear in a little as most of the tread disappears long before you reach the wear tabs?... should be interesting...

In other news, well as i say i haven't fully tested these tyres yet, take off is great, noise, what noise?, ultra smooth at low speeds, I don't know yet about high speed and as most of my issues are in the mid-range I don't know if the rumble has gone yet, I suspect that it has after seeing the state of the old tyres but reserve judgement until fully tested. While the car was on the ramp I gave it a good going over, there was a fair bit of play in the front wheel bearings although I hadn't noticed this in how the car handled and certainly hadn't heard anything unusual. It was a fair bit though, probably close to 5mm rock, or at least it felt like it. There is also a little rock in the diff but not much and I don't know what the spec is for this, when looking at the CV joint it's probably around 1/8" movement, feels more on the wheels but then it would due to the larger circumference. If anyone knows how much movement there should be here or if there shouldn't be any at all I'm all ears. Torque tube bearing has no up/down movement at all, there is a little rock which may be from the clutch end, it's solid at the gearbox, again I would be interested to hear from anyone who knows more about this area? No play whatsoever in the rear wheel bearings which was a nice relief/surprise. Checked the gearbox oil level which was as it should be, it is a fully synthectic oil which has now covered 14k miles but if problems persist i may try changing this to something like Royal Purple Max gear.

If I can I'll get out on a fast road tomorrow and see how things are, fingers crossed I now have a well-behaving car again...

cheers

Pete

 

[924Srr27l]

Here's a picture of one of the rears, this rubber is rock hard, has hard spots around the tyre that has caused uneven wear, if you run the flat of your hand around the center of the tyre you can feel the bumps/hard spots, best way to describe it is like flat spots on a race car although opposite if you get my meaning? Added to this in the first photo shown you can see the compound breaking down between the tread, not good, not good at all.

these give a performance not far behind slicks,

In other news, well as i say i haven't fully tested these tyres yet, take off is great, noise, what noise?, ultra smooth at low speeds, I don't know yet about high speed and as most of my issues are in the mid-range I don't know if the rumble has gone yet, I suspect that it has after seeing the state of the old tyres but reserve judgement until fully tested. While the car was on the ramp I gave it a good going over, there was a fair bit of play in the front wheel bearings although I hadn't noticed this in how the car handled and certainly hadn't heard anything unusual. It was a fair bit though, probably close to 5mm rock, or at least it felt like it. There is also a little rock in the diff but not much and I don't know what the spec is for this, when looking at the CV joint it's probably around 1/8" movement, feels more on the wheels but then it would due to the larger circumference. If anyone knows how much movement there should be here or if there shouldn't be any at all I'm all ears. Torque tube bearing has no up/down movement at all, there is a little rock which may be from the clutch end, it's solid at the gearbox, again I would be interested to hear from anyone who knows more about this area? No play whatsoever in the rear wheel bearings which was a nice relief/surprise. Checked the gearbox oil level which was as it should be, it is a fully synthectic oil which has now covered 14k miles but if problems persist i may try changing this to something like Royal Purple Max gear.

If I can I'll get out on a fast road tomorrow and see how things are, fingers crossed I now have a well-behaving car again...
cheers
Pete

The S02 Bridgestone's have a soft compound (for road use), and like competition tyres if the car has not done many miles in 2 years and has been through several summers and winters including a cold damp garage? the rubber will degrade and perish much faster than the majority of Road Tyres.

The irregular lumps indicates the tyre is bouncing or cupping due to a few worn and incorrect things:
http://www.freeasestudyguides.com/tire-wear-patterns.html

The Dunlop compound will be harder than the Bridgestone's, I've no idea what or how a road tyre can perform anything like a racing slick ? this is the typical Marketing hype I'd say!

Are your wheels the stock offset early ET23? Is your car the early turbo model?

R

 

[edh]

Sounds promising Pete
Interested to hear how the new tyres go - I need to replace my S02's on the 996. Nearly worn out & very noisy. Considering Yoko V105's at the moment. Can't get the RT flavour of the dunlops in 255/40/17, only Sport Maxx https://www.dunlop.eu/en_...8-Y-4038526248633.html

 

[PSH]

Hi guys

Yes, Roger, it's an early Turbo with the ET23 offset, I'm not so sure about Bridgestone compound being soft? I was told the opposite and would have to side with this as they felt very hard on the road before the troubles began, unusable after. It's not just a case of the tyre being cupped as you put it, there are hard patches with a change in colour as if the compound wasn't blended correctly with the softer material wearing quicker than the hard, it wasn't an even pattern around the tyre as you might expect with abnormal wear due to worn suspension components. Once the wheels were off rolling them across the floor showed then to wobble all over the place, in comparison the new tyres rolled in a nice straight line with no sign of a wobble. The cupping was only on the rears which is probably why I could feel most of the rumble from the rear and nothing from the front, also the cupping wasn't even around the tyre as you might expect if caused due to worn suspension components, it was erratic.
Today I have tested the car at high speed, it's such a transformation, very sure-footed, amazing grip in the wet that gives one complete confidence in the cars ability to hold the road. Had a big Merc try to play on a fast road, let him try to draw level and then accelerated to see how he would do but more importantly see how the tyres behaved in wet conditions....I won't mention speed attained for obvious reasons...the merc tried hard, at 54% throttle he was matching my pace but was soon left wanting when I increased to 74% throttle at 1.3 bar, pushing me a good ten car lengths ahead of the merc, in a very short distance, overhauling it with each yard covered, I then pulled over to the inside and let him catch up and past, I had no intention of staying at that speed, it was then that I clocked his AMG badge on the rear... poor chap...
Ed, I love these tyres, I would say better than Goodyear F1's which had always been my preference in the past, those tyres used to last 5 years with little wear, we shall see how these Dunlop's do on the wear side of things. I tried braking from high speed in the wet, amazing grip, the car must be well set up too as no movement to either side, just nice and straight, no lockup naturally, just good solid braking.
Just to be sure I will recheck the wheel alignment soon, see if my son can book me in sometime this week.

Anyway, I'm happy again, clearly, I had been getting a little paranoid but even though things seem sorted I will at some point strip down the rear and renew the components that have been there since the car was built, might do this once i have moved, best find somewhere with a good garage on the property, it may take a while to do this... I would like to find out the backlash spec for the diff too to see if this needs rebuilding at some point, I have tried to search on google but haven't found any info on this. I have found some trouble shooters for the diff/gearbox but these all mention a sound?, I have no noise other than the normal chatter when sitting stationery sometimes which I've had since owning that car (two gearboxes) and have heard mentioned as normal countless times before.

Cheers

Pete

 

[924Srr27l]

Hi guys

Yes, Roger, I'm not so sure about Bridgestone compound being soft? I was told the opposite and would have to side with this as they felt very hard on the road before the troubles began, unusable after.

The cupping was only on the rears which is probably why I could feel most of the rumble from the rear and nothing from the front, also the cupping wasn't even around the tyre as you might expect if caused due to worn suspension components, it was erratic.
Cheers
Pete

If you still have them check the sidewall it was read treadwear 140 I think from memory, Bridgestone use a very stiff sidewall and a
soft compound they are the worst tyres to fit and demount as the sidewalls have no give in them.

In comparison a R888 Trackday tyre is Treadwear 100 and a Michelin Pilot Sport 320, but the Michelin has a soft sidewall so
they work the exact opposite the more compliant sidewall heats up quicker and hence the compound has to be harder to stop it overheating which is why Michelin's last longer. I think your Dunlop's are about 240 treadwear so harder than the S02's when new but not when they are 6 months+ older.

I'm guessing you've had them on the car for years? and if so this is why they transmitted so much noise as the blocks harden
and then start to wear erratic because there is not enough compliance (Give) from the sidewall.

Cupping always happens on the rears as they only sit upright and do not turn like the fronts, so alignment is worth checking
as you may have something out or even a worn shock absorber which in time will cause your new tyres to wear erratically.
How old and how many miles have the rear shocks done ?

R

 

[Dan944t]

Hi Pete,
glad to hear this could have just been those s02s ?? Same problem I had with mine, hardly used them and they all cracked in a year and half and went hard. Hopefully happy motoring from now on??

I got news from serdi, that my short block is ready with its wet liners in and new rods , Iasa pistons and rods head balanced/polished crankect, lightened flywheel, ect........ well the price was a bit of a shock to the system ! But you get what you pay for and i have every faith that I wouldn't trust anyone else . im sure I paid less for my car back in the day when. I bought it ?? ( no joke ) who said these are a poor mans porsche???

soon as I get the new house refurbed and buikd the wife a beuty room in one of the outbuilding s it's time to get a space ready for the big rebuild, I'm hopeing by winter I will make a start?

atb
daniel ??

 

[PSH]

sounds good Dan, wet-liners would have pushed the price up for sure...the 951 was never a poor man's car, as I've said before it cost substantially more than a two-bed house in London, a very rich man's car for sure. Hope you get it rebuilt soon...I took the car on some twisty roads this evening, my passenger commented on how well it held the road while being ultra smooth. I have to say it felt great, I just let the car take the apex of the multiple S-bends at some speed on a downward slope, it sure did feel good..

Pete

 

[blade7]

I got news from serdi, that my short block is ready with its wet liners in and new rods , Iasa pistons and rods head balanced/polished crankect, lightened flywheel, ect........ well the price was a bit of a shock to the system ! But you get what you pay for and i have every faith that I wouldn't trust anyone else .

I'm interested why you went for wet liners, that's a big job. Alusil dry liners used to be available, though iron seem to be the favoured material these days.

 

[Dan944t]

I got news from serdi, that my short block is ready with its wet liners in and new rods , Iasa pistons and rods head balanced/polished crankect, lightened flywheel, ect........ well the price was a bit of a shock to the system ! But you get what you pay for and i have every faith that I wouldn't trust anyone else .

I'm interested why you went for wet liners, that's a big job. Alusil dry liners used to be available, though iron seem to be the favoured material these days.

Hi blade 7 ,

well one of my cylinders had a split all the way through so it was toast, and I wanted to keep the original numbers on my engine, and with the power mods I have and want which is somewhere between 350-450 I wanted cylinders that were going to withstand the boost if I wish to up it from 18 psi to possibly 21 if and when I choose to withought the same thing happening.
With taljing to john at serdi he works alongside Westwood who make these but could be wrong on this name? He and they recommended these for pure strength and so I've had my short block cylinderes machined away with a super large mill that serdi have and these new wet liners which are .05 larger installed. I have racing Iasa pistons the same as Pete, and I'm a ginipig on a set of racing conrods that John had made for me in Milan and I'm the first 944 turbo owner to have the first set so fingers crossed ??

i have a coupke of pic of the liners and my block machined down down and in fact finished I think if I can find them I will put them up tommorow if I can. I'm sure pete won't mind Me putting these up on his thread, if I can figure out how to that is?

atb
daniel

 

[Dan944t]

This is my block and our can see my cylinders have been milled down by a huge digital mill.

and these are the bloody expensive liners

 

[PSH]

Hi Daniel

Photobucket is nolonger an option unless you pay their blackmail levy of $400....try hosting your photo's to another free site...I have moved all mine to 'Imgur' which works fine. I'm not sure how you do this via phone though..I do all mine via PC except Facebook which is fairly easy to do using the phone.

Cheers

Pete

 

[Dan944t]

Cheers Pete will try this later free work no see how I get on, as I don't have pc just iPhone ??

 

[blade7]

Hello Daniel
The split cylinder in your block explains the wet liner route, and as you say a stronger block overall. It would have been the ideal time to up the capacity but you have to draw a line somewhere I guess. Good luck with the build.

 

[Dan944t]

Hello Daniel
The split cylinder in your block explains the wet liner route, and as you say a stronger block overall. It would have been the ideal time to up the capacity but you have to draw a line somewhere I guess. Good luck with the build.

Hi blade7,

yea sorry mate I thought you knew from a past post of mine that i had a split cylinder.

I also had a tough decision to make at the time to push the cappacity up,as u say, but decided I was happy trying to just achieve a quicker spool time with the smaller turbo,abad a bit more torque for future mods ( probably just a vitesse maff kit and stand alone and a set up by the wizard) but I shall be picking Petes brains when I do have the funds in place in the future as his posts in the short time I've been on here have cost me so much money that I feel he owes me!????

atb
daniel ??

 

[blade7]

I can just about remember what I had for breakfast . With your power goals you'll definitely need a bigger turbo. And Vitesse or VEMS, with the dismal $ exchange rate and import costs I'd suggest the VEMS option.

 

[PSH]

Hello Daniel
The split cylinder in your block explains the wet liner route, and as you say a stronger block overall. It would have been the ideal time to up the capacity but you have to draw a line somewhere I guess. Good luck with the build.

Hi blade7,

yea sorry mate I thought you knew from a past post of mine that i had a split cylinder.

I also had a tough decision to make at the time to push the cappacity up,as u say, but decided I was happy trying to just achieve a quicker spool time with the smaller turbo,abad a bit more torque for future mods ( probably just a vitesse maff kit and stand alone and a set up by the wizard) but I shall be picking Petes brains when I do have the funds in place in the future as his posts in the short time I've been on here have cost me so much money that I feel he owes me!????

atb
daniel ??

Haha.....I wonder if I can say the same to Andrew Sweetenham (original owner of Promax), he started me off with a boost enhancer 18 years ago....the reason that I didn't go mad on capacity was due to not wanting to lose that magic feel that the 951 engine gives. I didn't want to change the liveliness of the engine just for a little more low down torque, having said that the capacity has increased a little, iirc just under 100cc, I love how the engine goes and sounds today, has a real rasp to it plus the burble and odd pop on overrun. Talking of costs, what have you decided on head/main studs and conrod bolts, I ask as I note your hoped-for power gain...the upper end IMHO would be best to have better fastening but these aren't cheap.

Pete

 

[Dan944t]

Hi Pete, If im nit mistaken I went for Apr head studs and possab the same with Conrods but will need to double check on the conrods with john?

his also rewelded my head and skimed and is now I'm told a mirror finish, also installed new valve guilds even though I just just got all this done 10 miles before the cylinder cracked! Also recut the valves in , and I asked him to install a steam vent kit in the head on number 4 cylinder to take any bibles out to try and avoid it over heating. but I asked for the head not to be reassembled as I'd like to do some mild port finishing on any rough cast joins, and obviously can't on the ceramic side, but inside where the valve ports are where I'd like to investigate. I've already started on the manifold before the house moove and that diabolical and I think I'll nick a tiny bit of usable power by doing all this but obviously not going mad on it.

hi blade, I understand what our saying about a bigger turbo but in all honesty Im exactly the same mindset as Pete as in I love the way the little turbo spools so rapidly and I just try to reduce the spool time as I'm more into the acceleration more then top end.

Ive also spent well over £6000 on mods alone like larger modded intercooler, 55lb injectors, heavy duty vaccine lines , Tial 38mm dual port wastegate, sports backbox straight through, manual boost controller, stage 2 chipset set from 18psi with reworked AFM, larger motorsport fuel pump, upgraded fuel preasure regulator, 993 recirculating/dump valve, new diz cap and leads, k&n open air cone, lightened, flywheel, crank scraper, lighter racing Iasa pistons, custom made lighter race conrods, mild porting ......probably forgot stuff but withought to sound arrogant becuase I'm really not the type, but I think I'm pretty close if not past my goals already. And with a stand alone and a vitess or similar as you say, and set up by the wizard hopefully I have the pleasure , I think it will be a really rapid 1980's porsche ??

Atb
daniel