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4 Aug 2006, 16:35 (Ref:1673255) | #51 | ||
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Last edited by phoenix; 4 Aug 2006 at 16:38. |
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4 Aug 2006, 19:39 (Ref:1673411) | #52 | ||
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Hmmm.
My panhard rod is so close to the axle that the links won't make massive amount of difference. According to all the googling the fact that the rod slopes upwards from the body to the axle is not a good thing. I suppose the question is whether the extra weight of a watts linkage is going to offset the geometry improvements. I think I'll have a measure tomorrow and work out the roll centres. May also drill some new panhard mounting holes and have a play in the last couple of races (don't read this bit Colin/Rob!). |
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5 Aug 2006, 09:39 (Ref:1673825) | #53 | ||
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What is also true is that the Panhard rod body mounting should definitely be above the axle mounting! Remember that if you add the weight of a Watts linkage you will also remove the weight of the existing Panhard rod, so it's not all bad. I also think that the increased cornering speed potential of getting the suspension right will far outway the slight weight penalty. |
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5 Aug 2006, 12:48 (Ref:1674028) | #54 | |||
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5 Aug 2006, 17:02 (Ref:1674231) | #55 | |||
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From the puhn book the virtual meeting pount of the lower arms is probably raising it a bit but the magic numbers are - Front roll centre is 12cm above ground. Rear roll centre is 23cm above ground (plus any effect of the lower arms). How does this sound? For info I am going to raise the body end of the panhard rod for the next race by 1-1.5 inches so it is just sloping downwards body to axle. Should be interesting to see what, if any, difference I feel. Will report back. And the watts linkage is designed in case I do detect a difference. |
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5 Aug 2006, 17:03 (Ref:1674232) | #56 | ||
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Lower the axle mounting points of the lower trailing arms Dennis so that the trailing arms are level, they definitely do not want to be pointing up in the sky as a result of lowering.
Disregard this Dennis, we cross posted! Last edited by Al Weyman; 5 Aug 2006 at 17:08. |
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5 Aug 2006, 17:10 (Ref:1674238) | #57 | ||
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It sounds like a similiar set up to the old Talbot which definitely went bound especially if you used poly bushes, why not just adabt an Escort 5 link kit and have done with it.
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5 Aug 2006, 18:22 (Ref:1674293) | #58 | |||
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It would be nice for the top of the axle not to nod backward and forwards as it moves up and down, or you accelerate/brake! |
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5 Aug 2006, 23:12 (Ref:1674486) | #59 | |
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Dennis,
just out of interest and perhaps to further fuel the current thread... What is your rear toe-in and camber set at? Does it lift a rear while cornering? Last edited by glenn22481; 5 Aug 2006 at 23:15. |
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6 Aug 2006, 01:24 (Ref:1674522) | #60 | |||
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That said I am notorious for having odd set-ups, ringing the crap out of my cars and them for someone else to jump in and ask how can I keep the thing on the black stuff (insert Gorilla driver joke here) Mind you my last Strut front 5-link rear car were I played with this was a FWD. My last RWD competition car was… hmm 12+ years ago with a RA23 Celica, and I didn’t really “think” through that car, I just tended to do the “standard” mods that everyone else said you “should” do. |
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6 Aug 2006, 07:09 (Ref:1674621) | #61 | |||
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In reality it has about a 1/4 of a degree of negative, no idea how/why. No it doesn't lift. |
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6 Aug 2006, 08:05 (Ref:1674645) | #62 | ||
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Ben has noted (in this thread even) that the relative RC height should be a function of the yaw inertia. If you have a tank you might want a low FRC and a high RRC to get the thing to turn whereas in a small open wheeler I'd be suprised if either RC was above 100mm.
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6 Aug 2006, 08:52 (Ref:1674681) | #63 | ||
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Last edited by glenn22481; 6 Aug 2006 at 08:59. |
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6 Aug 2006, 09:22 (Ref:1674702) | #64 | ||
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When raising the chassis end of the panhard rod you should aim to have the rod still angled up, or at a mimnimum horizontal, when the suspension is at full bump. Will the 1.5 inch increase achieve that? If it does, you should notice a difference. |
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6 Aug 2006, 14:31 (Ref:1675439) | #65 | ||
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I'll have another look at the rear roll centre, I'm afraid I threw my toys out the pram when I spend an hour accurately measuring the front suspension points only find I couldn't save them properly on the demo copy of susprog3d and wasted my time.
Part of the reason it is quite low is because I corrected the lower arms with 'traction brackets', the rod attaches to the axle at the bottom of the casing rather than the top and Corolla's seem to have been designed to run a couple of inches lower than standard then got jacked up for some bizarre reason. Out of interest, correcting the lower arms and adding 1/2 a degree of castor with no other changes transformed the car from understeer to oversteer. This is why I am now chasing geometry rather than spring rates to correct the balance. Correct, it is unlikely that the 1.5 inch change in chassis attachment will achieve the 'ultimate goal', but I don't want to change things too much at first just in case it goes horribly wrong. In the end the car still usually wins it's class and there are a lot of changes planned over the winter, including the possibility of a watts or wobb linkage. |
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6 Aug 2006, 15:15 (Ref:1675510) | #66 | |||
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6 Aug 2006, 19:00 (Ref:1675786) | #67 | |||
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As for adding toe in, I'm really not sure. I was hoping to play with this on the kit car but that would require an engine!! |
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6 Aug 2006, 22:22 (Ref:1676025) | #68 | ||
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Denis,
1deg neg, 10mins toe in. Trust me, I'm a doctor. Rob. |
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7 Aug 2006, 07:03 (Ref:1676248) | #69 | |||
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Particularly given that splines for the diff are really 'designed' for a zero degree camber angle. Or is it just big V8 Astra's that it causes reliability problems with |
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7 Aug 2006, 07:26 (Ref:1676262) | #70 | ||
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Do what was rumoured to have be done on certain 'works' SDI's, run a Granada CV joint within the axle:-)
I definitely would not have the bottle to bend a Chevy axle with the 'legendary' GM break a halfshaft and lose a wheel C-Clip halfshaft retaining setup. Last edited by Al Weyman; 7 Aug 2006 at 07:29. |
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7 Aug 2006, 07:29 (Ref:1676265) | #71 | |||
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7 Aug 2006, 17:07 (Ref:1676776) | #72 | |
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Done it myself on a Ford English and a Morris Ital axle. Mind you I did only put 130bhp through it and the casing was comprehensively braced...
The splines will take a degree or so of misalignment without problem. THe whole things swimming in thick oil anyhow - imagine the amount of movement the teeth of the CPW see versus a 1 deg misaligned spline. G |
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7 Aug 2006, 22:04 (Ref:1677079) | #73 | ||
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If your axle has fully floating hubs, you're OK with that sort of a mod Denis.
My rear axle is not a reliability issue, and as "Strange" as it seems, it is equipped with fully floating hubs. Had I gone for the Winters quick change axle, I could have had "cambered" axle tubes, and with a twist, I can change camber, and toe, in one movement (obvious really!). Al, you don't mean those works Rover's were bent do you? No don't start the Volvo rockers issue again.... and like you, the Chevy diff is well known for letting those C-clips loose without the addition of any tweeks. That's why I went for the Strange/Ford 9". Rob. |
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8 Aug 2006, 06:56 (Ref:1677290) | #74 | |||
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8 Aug 2006, 12:19 (Ref:1677566) | #75 | ||
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DENNIS YOU ARE A FUNNY MAN!
Had to run the original Axles Rob so no choice. I do have disc brakes on both cars so figure if an axle shaft breaks the caliper may stop the wheel going walkies, never tried the theory though! The 'Chevrolet' show car IROC promotional racer I am renovating in fact has a Ford axle (from new) with fully floating hubs, Strange axles and I think it has a SPool, not sure. Either that or a very tight locker! Last edited by Al Weyman; 8 Aug 2006 at 12:21. |
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