Reinaldo Posted February 25, 2009 Author Report Share Posted February 25, 2009 Since I have started this post, I would like to thank all of you (Jean, Jim, Stuart, Jamie and Richard) for the help. After changing the fulcrum pin during the last weekend I got much better camber (1/2 degrees negative both sides) and also a progress on caster (was around 1 degree and now is around 1 and 1/2 degrees). I will need to fine tunning (play with the shims) for better caster. One promissing indication is that I found the measurements done in the past (before frame-off restoration) and camber was 2 and 1/2 degrees at one side and 3 degrees on the other side! Regards, Reinaldo Quote Link to post Share on other sites
graeme Posted February 25, 2009 Report Share Posted February 25, 2009 Well thats it then toys out the pram and the workshop manual in the bin Im going to get a job sweeping the roads .Having talked to most of the experts in the western world this morning I hold me hands up and stand corrected. Top fulcrum mount faces away from the engine same as TR5/6. Stuart. Stuart, I think you have been led astray by the TR4A manual, which is basically a very poorly updated TR4 manual. There are several errors apart from the upper fulcrum, for example, the wiring diagram is purely TR4 and does not reflect the TR4A. You are an acknowledged expert in the field of TR's but even experts occasionally get it wrong. Best regards Graeme Quote Link to post Share on other sites
tonycharente Posted May 28, 2012 Report Share Posted May 28, 2012 Hello all, Just been reading through this excellent topic - as my TR4A has too much negative camber at the front. I'll be checking later to see which way round the fulcrum pins are mounted, but as the camber is greater on the left than on the right I expect I'll need to play with the number of lower wishbone shims too, come what may. Currently there are three shims in each location on both sides. Which leads me to three questions, please. How much, in inches or cms measured at the top of the rim versus the bottom of the rim, does one degree of camber represent? And what is the impact (in degrees - or in distance as measured above) of removing one shim, front and rear? Or putting it another way, if I remove all three shims in one go will this be way too much correction? Finally I know you are supposed to weight the car up, but not having two friends around at present, what, and in which direction, is the effect of weighting the car up? This is just to understand whether my excessive camber problem gets worse or diminishes when the car is properly weighted up. Many thanks, as ever, Tony Quote Link to post Share on other sites
tonycharente Posted May 28, 2012 Report Share Posted May 28, 2012 Hello again, Further to my above three questions, here comes a fourth, please! I have this evening taken the front wheels off to examine the way the fulcrum pins are fitted : they are fitted curve towards the engine. According to the highly detailed (and very definitely TR4A specific) diagram AND PHOTOS in my original (period) workshop manual this is the correct way round for a TR4A, so despite some suggestions to the contrary I believe that Stuart was right all along. My fourth question is to ask whether turning them round (curve towards the wheel) increases or decreases negative camber, and by how much. (I've sort of gathered that turning them round would increase the negative camber and make my problem worse, but I'd just like to be sure I've understood.) Many thanks, Tony Quote Link to post Share on other sites
tonycharente Posted May 29, 2012 Report Share Posted May 29, 2012 (I've sort of gathered that turning them round would increase the negative camber and make my problem worse, but I'd just like to be sure I've understood.) CORRECTION Having spent all night thinking about it (!!! how sad is that? !!!) I think that turning the fulcrum pins round (moving the curve to be towards the wheel) would in fact decrease the negative camber and so improve my position. But which has most impact (and how much?) flipping the fulcrum pins or removing shims? And what is the impact of weighting the car up - what impact on the measured camber? Thanks again, Tony Quote Link to post Share on other sites
stuart Posted May 29, 2012 Report Share Posted May 29, 2012 If you fit them the correct way round for an IRS car i.e. with the curve towards the shock mount then three shims on the lower mountings is pretty much the correct starting point. If you change them over and then take the car for a run around the block and then park it on level ground you should be able to get pretty much the correct measurements. Loading will apply more for rear axle settings though a full 5 gallon can on each seat would help. Stuart. Quote Link to post Share on other sites
littlejim Posted May 29, 2012 Report Share Posted May 29, 2012 (edited) Roger Williams recommendation for TR4A's re curve of inner front suspension mount. (Opposite to what Tony is going for.) Would be interesting to try it both ways and measure the difference. I did it the above way because the guru (Roger) said so. Hope he is right. Seems to work OK on mine. Looking at the picture certainly gives the impression that reversing it would move the top of the wheel out decreasing negative camber. Edited May 29, 2012 by littlejim Quote Link to post Share on other sites
tonycharente Posted May 31, 2012 Report Share Posted May 31, 2012 The fulcrum pin is correct for 4a. It changed for 5/6. Stuart This picture isnt very good but does clearly show the orientation of TR4 top fulcrum pin as curved towards the engine. If you check the Workshop manual section 4.118 Fig.29a it clearly shows the orientation of the fulcrum pin on 4a suspension as curved towards the engine as well. Stuart Well thats it then toys out the pram and the workshop manual in the bin Im going to get a job sweeping the roads . Having talked to most of the experts in the western world this morning I hold me hands up and stand corrected. Top fulcrum mount faces away from the engine same as TR5/6. Stuart. If you fit them the correct way round for an IRS car i.e. with the curve towards the shock mount then three shims on the lower mountings is pretty much the correct starting point. If you change them over and then take the car for a run around the block and then park it on level ground you should be able to get pretty much the correct measurements. Loading will apply more for rear axle settings though a full 5 gallon can on each seat would help. Stuart. Hello Stuart, and thank you very much for suggestion. However I don't understand why "most of the experts in the western world" believe that the correct way round for the fulcrum mount on the TR4A is anything but as very clearly show in the official period workshop manual - not just the TR4A diagram that you quoted but also the PHOTOS of what can only be TR4A front suspension. I know it is heresy to query Messrs Williams and Revington, but the PHOTOS are not a draughtman's error - so what is the basis for believing that the manual is wrong? What made you change your mind, please? Returning to your suggestion, you can probably sense that I am reluctant to swap my fulcrum mounts round if they are not in fact the wrong way round - I would prefer to remove shims instead - it looks to be much easier and would (if I am right) leave the car "original". But pragmatically which will have the most impact, flipping the fulcrum mount or removing shims (I have 3 shims in place). Since my initial post I have been able to measure my negative camber - it is approx. 2° NEG on the left side and 1.5° NEG on the right. What impact would removing all 3 shims have? Is my camber so far out that I have no choice but to flip the fulcrum mountings, original or not? Finally it would appear that if your camber is going to be excessive versus 0° it is better to err on the negative side - is that right? (The Kastner competition book recommends 1/2° NEG to - 3/4° NEG) Or am I just trying to make myself feel better? Many thanks again, Tony Quote Link to post Share on other sites
Alec Pringle Posted June 1, 2012 Report Share Posted June 1, 2012 I can remember a similar debate c1976 . . . . . the eventual conclusion at the time being that early 4As had the top fulcrum pointing inwards, and that fairly soon into production the fulcrum was 'flipped'. And then stayed that way throughout IRS production. Bear in mind that at the time there were still a fair few unmolested original cars to utilise as comparison. Maybe it was a bean counter's decision, as in save the cost of two shims per car or somesuch ? Cheers, Alec Quote Link to post Share on other sites
stuart Posted June 1, 2012 Report Share Posted June 1, 2012 My 4a has the top fulcrums fitted as per the workshop manual (curve facing the engine) and three shims in the bottom and it has quite a lot of neg camber but that is how I like it. From your measurements quoted above by remove shims then you should be able to get to an equal negative camber as per Kastners or thereabouts which should give you what you require provided the turrets are straight. Stuart. Quote Link to post Share on other sites
tonycharente Posted June 1, 2012 Report Share Posted June 1, 2012 (edited) I can remember a similar debate c1976 . . . . . the eventual conclusion at the time being that early 4As had the top fulcrum pointing inwards, and that fairly soon into production the fulcrum was 'flipped'. And then stayed that way throughout IRS production. Bear in mind that at the time there were still a fair few unmolested original cars to utilise as comparison. Maybe it was a bean counter's decision, as in save the cost of two shims per car or somesuch ? Cheers, Alec Thank you Alec - what you say explains the difference between the workshop manual and the statements made about what is "correct". And as a retired Chartered Bean-Counter I can but applaud the resultant huge cost saving - not to mention the huge weight saving !!! My 4a has the top fulcrums fitted as per the workshop manual (curve facing the engine) and three shims in the bottom and it has quite a lot of neg camber but that is how I like it. From your measurements quoted above by remove shims then you should be able to get to an equal negative camber as per Kastners or thereabouts which should give you what you require provided the turrets are straight. Stuart. Thank you again Stuart. I am going to start by leaving my fulcrums as found (curve facing the engine) and removing both sets of three shims from the left side of the car to see what that does. Ideally that might leave me with a small negative camber. Depending upon what I find, I'll then try removing just two shims from the right hand mounts - in the hope of getting approx. equal small negative camber on both sides. However if removing all the lefthand shims still leaves me with way too much camber, then I'll have to face up to flipping the fulcrum mounts, original or not. I will report back, promised! Thanks to all Tony Edited June 1, 2012 by tonycharente Quote Link to post Share on other sites
tonycharente Posted June 10, 2012 Report Share Posted June 10, 2012 Hello all, Reporting back so far... I removed the two sets of three shims from the front left - the difference it made was not drastic - it's about equalised my camber left compared to right, so that's good, but I still have more camber than I should have. So my next move will be to flip the fulcrum pins. Only thing is, as far as I can estimate this will have even less impact than removing three shims. Does anyone know which should influence camber most - removing thee shims or flipping the fulcrum pins? Again I will report back in due course. Thanks to all, Tony Quote Link to post Share on other sites
stuart Posted June 10, 2012 Report Share Posted June 10, 2012 (edited) They both influence the camber and I would say three shims is probably slightly less than flipping the top pin. (It does though sound as if your left hand turret may be bent in a bit in comparison to the right one). Have you tried a plumb line measure to check this?. Stuart. Edited June 10, 2012 by stuart Quote Link to post Share on other sites
ChrisR-4A Posted June 10, 2012 Report Share Posted June 10, 2012 Hi all, one thing no one has mentioned is the effect of lowering the front suspension on camber angle. Having fitted some stiffer and about 3/4 ins shorter front springs a few years ago I did notice the negative camber increased to about 1.7deg. On standard 165 tyres this did not improve the handling but did increase the front tyre wear on the inside edge. After getting through 2 sets of tyres which still had 6mm of tread in the centre I fitted some 5mm poly spacers under the front springs which reduced the camber to about 1/2deg neg. Car handles just fine and tyre wear is much less. As is often the case leaving things near or as standard is often the best option. Regards Chris Quote Link to post Share on other sites
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