chrisgixer Posted November 6, 2015 Report Share Posted November 6, 2015 Vauxhall omega 3.2 elite Lsd retro fitted. Sports suspension lowered 20mm at the rear. (30 at the front. All else is standard with this car at the rear. Wim set up a year ago, so might be due. But a local company has checked the set up again and looks ok, although I can't lay my hands on the sheet to quote figures until later. Problem is the rear is steering itself out of line with the front and causing me to correct it with the steering wheel. ( trampling at the rear basically) This got worse on fitting new tyres. So either the tyres are at fault or its highlighted an issue. It's dive had a puncture, so I have free fitted an old part worn from the previous set that came off the car last time. It has roughly half the tread of the drivers side, so this is causing a pull on full throttle and a pull back the other way on throttle off. Questions are, is the pull on full throttle normal on a rear wheel drive with uneven tyre wear (bigger outside diameter) on one side? Guessing yes. Or is that a sign of an issues on its own. Could the lsd be giving uneven or odd drive to each wheel and causing a loss of control or a variation on rear thrust angle. The only part not replace at the rear are the trailing arm bushes that seem OK levering with a bar. It did have poly subframe bushes but these have been removed for oe ones to discount them. The fault remains although the effect is more....wooley/less pronounced. Front end is absolutely perfect. No pulling. Fronts are Michelin pilot super sports mo Rears are conti sports contact 3 mo, and previous sets have been fine. I is befuddled. Quote Link to comment Share on other sites More sharing options...
Tony Posted November 6, 2015 Report Share Posted November 6, 2015 Torque steer can be due to incorrect rear toe ( thrust angle ) A difference in the rear tyres sidewall rigidity ( slip angle ) and the drive shafts going off line which is normally a diff mount issue. Quote Link to comment Share on other sites More sharing options...
chrisgixer Posted November 6, 2015 Author Report Share Posted November 6, 2015 Not tread depths at all? :-\ torque steer does disapear with even tyre tread wear. ....leaving only the tramlining at the rear as an issue. Interesting topic, didn't consider Dif position at all. Quote Link to comment Share on other sites More sharing options...
Tony Posted November 7, 2015 Report Share Posted November 7, 2015 Tread depth wouldn't be an issue at the rear but the compound between tyres can be under hard thrust. Quote Link to comment Share on other sites More sharing options...
chrisgixer Posted November 27, 2015 Author Report Share Posted November 27, 2015 Found the last data sheet Rear settings Toe -19each side. Thrust angle zero Camber -1.90 left -2.20 right Quote Link to comment Share on other sites More sharing options...
chrisgixer Posted November 27, 2015 Author Report Share Posted November 27, 2015 So degrees not minutes Quote Link to comment Share on other sites More sharing options...
Tony Posted November 28, 2015 Report Share Posted November 28, 2015 Yep degrees.... I doubt it's reading -0.19 because a negative toe position on a RWD is not desirable. Quote Link to comment Share on other sites More sharing options...
chrisgixer Posted November 28, 2015 Author Report Share Posted November 28, 2015 Ahem, yes quite right. *Cough*notanegativefigureatall*Coughcough* Whoops. Quote Link to comment Share on other sites More sharing options...
chrisgixer Posted November 28, 2015 Author Report Share Posted November 28, 2015 So if coveting to minutes that's not far off the ideal setting if I understand correctly. ...? Quote Link to comment Share on other sites More sharing options...
Tony Posted November 29, 2015 Report Share Posted November 29, 2015 It's not end of days...... How were the diff mounts by the way? Quote Link to comment Share on other sites More sharing options...
chrisgixer Posted November 29, 2015 Author Report Share Posted November 29, 2015 Absolutely fine. No tearing or rust separating the rubber from the metal. There are three sets of bushes of relevance. The "donuts" at the leading ends of the subframe, these mount under the door area under a triangular plate, as I'm sure you know. Then at the rear of the subframe there's what we often incorrectly refer to on the omega forum as the Dif blocks or Dif bushes. This is because the actual Dif mount bushes that mount the Dif to the subframe never fail. The "Diff blocks" actually mount the rear of the subframe to the body. These often either seperate through rust over time, or get torn by tyre techs jacking on the Dif. Anyway, I can see no issues, the bolts are tight, all bushes are sound, there is no real way of miss aligning the Dif or having it move on the subframe, or the subframe moving on the body. Although it has had an lsd retro fitted. So, while I can't see how it could be miss aligned, I do wonder if there could be an internal issue with the lsd itself that's causing the symptoms. But nothing obvious comes up when briefly searching lsd's and handling. If not geo or bush issue, and not a Dif issue, that only leaves tyres, I suppose. Springs are both sound. I checked dampers a while back. Bilstein b4, no dead spots with constant damping throughout the stroke. Trailing arm bushes seem solid. Inboard side ones seem a softer construction as they both have very slight flex when really leaning hard on then with a pry bar. Outboard ones are rock hard, no play at all. Rear track rods are okay, no play in ball joints. (Although doubtless the adjusters are seized) Tyres are conti sports contact 3, 265/35/18 97y mo. Until now I have trusted them with very good straight line stbility. Continental say they have never had a stability issue with this tyre. (Well they would wouldn't they) But that to get two with a problem would be very highly unlikely. What is highly evident, is the rear end movement. A good deal of correction is required to keep the car straight on uneven road surfaces. The rear can be felt moving out of line with the front. ...and the same can be said with full throttle on, and full throttle off causing a correction one way on full power on, and a correction the other way with full power off. I don't get it to be honest. Quote Link to comment Share on other sites More sharing options...
chrisgixer Posted November 29, 2015 Author Report Share Posted November 29, 2015 Edited. Fuddled the edit button. lol Quote Link to comment Share on other sites More sharing options...
chrisgixer Posted November 29, 2015 Author Report Share Posted November 29, 2015 Oh. Wheel bearings. Left rear I have replaced. Right rear is original with no play, although they are a double race bearing so don't seem to fail with play, they just get very noisy it seems. There's no obvious bearing noise that I can distinguish above the road noise. Sc3 are not particularly quiet tyres. Must admit I haven't checked the right rear bearing for flex. Quote Link to comment Share on other sites More sharing options...
Tony Posted November 29, 2015 Report Share Posted November 29, 2015 Definitely reading like torque steer.... Almost an inherent trade from a FWD whereas in a RWD it's normally tyres/ toe/ drive train. Quote Link to comment Share on other sites More sharing options...
chrisgixer Posted December 31, 2015 Author Report Share Posted December 31, 2015 Hi all Just to finish this off, I swapped the Dif out for a normal non lsd item and all is now well. Still some slight instability at the rear, but with the lsd removed it's now possible to feel that the remaining slight wander from the rear is almost certainly down to tyre wear. Certainly feels like normal tyre wear at least, so perfectly acceptable.... I could now re fit the rear poly bushes and see if that fixes the last 10% before tyres are due. (As one rear tyre is within 1mm of the wear bars) Anyway, car is now an absolute joy to drive again. Wohooooooo Thanks all for advise. Quote Link to comment Share on other sites More sharing options...
Tony Posted January 1, 2016 Report Share Posted January 1, 2016 Was you getting any noise from the diff? Quote Link to comment Share on other sites More sharing options...
chrisgixer Posted January 1, 2016 Author Report Share Posted January 1, 2016 Nope. No noise. Although the car now feels much smoother. Fluid under power and in corners. So the lsd was obviously poorly. It had a harshness that gradually worsened over time so I didn't really notice. ...at least not until it got VERY harsh and vibey in corners one evening on the drive home. A top up of about a quarter litre of sae90(?) dif oil stopped that, and obviously pointed to an issue with the dif, so out it came. Quote Link to comment Share on other sites More sharing options...
Tony Posted January 2, 2016 Report Share Posted January 2, 2016 Ah then well detected...... I've known of this before but the diff/ drive train was so noisy it diagnosed it's self. Quote Link to comment Share on other sites More sharing options...
chrisgixer Posted January 3, 2016 Author Report Share Posted January 3, 2016 Thanks. Question now is, do I bother getting the bloody thing refurbed...? Given the lack of parts and my current severe dose of cba..... Quote Link to comment Share on other sites More sharing options...
Tony Posted January 4, 2016 Report Share Posted January 4, 2016 I think i would sit on it for now.... Would it cost much to mend and if done is it worth much? Quote Link to comment Share on other sites More sharing options...
chrisgixer Posted January 4, 2016 Author Report Share Posted January 4, 2016 £200 seems to be the going rate, used. So probably not. ....although, if it could take the horse power of an ls1 it might come in handy on the project. ....but then we're back to can't cba with the project either. lol Quote Link to comment Share on other sites More sharing options...
Tony Posted January 5, 2016 Report Share Posted January 5, 2016 Well it's a sellers market in the summer when projects come to light so as said maybe just sit on it for now. Quote Link to comment Share on other sites More sharing options...
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