foster461 Posted July 15, 2018 Report Share Posted July 15, 2018 As I drive the TR3 more i'm noticing that it is very easy to break traction when resuming from a stop. It is especially noticeable when turning left or right at an intersection. All new or rebuilt suspension, new tires. Is this tire chirping normal or do I have something else going on. Tire pressure perhaps ? Stan Quote Link to post Share on other sites
stuart Posted July 15, 2018 Report Share Posted July 15, 2018 Always is quite easy to get them to break away like that as there isnt much weight on the rear, what pressures and how old are the tyres? Also a lot of your town roads are concrete so slightly less traction than on tarmac. Stuart. Quote Link to post Share on other sites
foster461 Posted July 15, 2018 Author Report Share Posted July 15, 2018 Always is quite easy to get them to break away like that as there isnt much weight on the rear, what pressures and how old are the tyres? Also a lot of your town roads are concrete so slightly less traction than on tarmac. Stuart. Tires are 5 years old and inflated to 26 front, 28 rear. 165x15 Vredestein. No concrete up here in northern MA but it has been unseasonably hot lately and if anything the roads are stickier.. You are probably right Stuart, just a characteristic due to the light rear end. I can make the TR6 do it too but have to work harder. Quote Link to post Share on other sites
ianc Posted July 15, 2018 Report Share Posted July 15, 2018 As one turns, weight is transferred to the side of the car on the outside of the turn, so the rear wheel on the inside of the turn is relieved of weight and can spin. So, turn right and the right rear wheel can spin. In addition, the rotation of the prop shaft under power will tend to lift the right rear wheel - and can cause axle tramp if the dampers are in poor condition. Ian Cornish Quote Link to post Share on other sites
Don H. Posted July 15, 2018 Report Share Posted July 15, 2018 Sounds normal to me, Stan. I run 28 psi front and rear, same tires, and with a bit of throttle it's easy to break the back end free, especially (and advantageously) to tighten a line in a corner. Quote Link to post Share on other sites
Motorsport Mickey Posted July 15, 2018 Report Share Posted July 15, 2018 Sounds normal to me, Stan. I run 28 psi front and rear, same tires, and with a bit of throttle it's easy to break the back end free, especially (and advantageously) to tighten a line in a corner. Aaaahhhh that would be because you are still using the skills required to drive a car and not trying to fit an anti roll bar to the front. Mick Richards Quote Link to post Share on other sites
Colin Fairhurst Posted July 15, 2018 Report Share Posted July 15, 2018 Aaaahhhh that would be because you are still using the skills required to drive a car and not trying to fit an anti roll bar to the front. Mick Richards That hurts. Quote Link to post Share on other sites
TomMull Posted July 15, 2018 Report Share Posted July 15, 2018 As I drive the TR3 more i'm noticing that it is very easy to break traction when resuming from a stop. It is especially noticeable when turning left or right at an intersection. All new or rebuilt suspension, new tires. Is this tire chirping normal or do I have something else going on. Tire pressure perhaps ? Stan Stan, For what it's worth, I have to really try to get a chirp from mine, even when starting with the wheel turned. Sounds to me like a grabby clutch. It may work out with a bit of use. I find it hard to believe that a couple of pounds of air pressure would make a difference but certainly rule that out first. Tom Quote Link to post Share on other sites
Motorsport Mickey Posted July 15, 2018 Report Share Posted July 15, 2018 (edited) Too soft tyre pressures can allow the tyre footprint to "deform" upon weight transfer ( front to rear under power) reducing the grip through the tyre, especially if the car is doing it on intersections where you are likely to have some steering lock already input into it. That increase's the force required on the rear tyres to move the car forward, try upping by 4 lbs a tyre at the rear just to eliminate it from the mix, then if successful reduce it until you are happy with the compromise. Mick Richards Edited July 16, 2018 by Motorsport Mickey Quote Link to post Share on other sites
Motorsport Mickey Posted July 15, 2018 Report Share Posted July 15, 2018 That hurts. Only teasing Colin Mick Richards Quote Link to post Share on other sites
anotheralan Posted July 15, 2018 Report Share Posted July 15, 2018 What size tyres do you have? Sure to make a difference. 28 sounds on the high side to me. When i had my tr2. In 1966 and they put charts on the wall at the garage the recomm rear pressure for my Cinturatos was always a couple of pounds higher than the front and from memory something like 24/26. So that is what i still do. But i do have fatter tyres now but still Cinturatos. How much of a hurry are you in? Do you park outside banks? Quote Link to post Share on other sites
Motorsport Mickey Posted July 15, 2018 Report Share Posted July 15, 2018 What size tyres do you have? Sure to make a difference. 28 sounds on the high side to me. When i had my tr2. In 1966 and they put charts on the wall at the garage the recomm rear pressure for my Cinturatos was always a couple of pounds higher than the front and from memory something like 24/26. So that is what i still do. But i do have fatter tyres now but still Cinturatos. How much of a hurry are you in? Do you park outside banks? Alan, Manufacturers like drivers to have understeer, then the car goes straight on until excess speed is scrubbed off and you can ( hopefully) turn into the corner. So they suggest lower tyre pressures which allows the tyre footprint to roll and lose grip = understeer. If you want to remove understeer without going into front and rear anti roll bars ( see numerous other threads), raise the pressures in the front and/or reduce pressures in the rear. Mick Richards Quote Link to post Share on other sites
anotheralan Posted July 15, 2018 Report Share Posted July 15, 2018 Thanks for that Mick. Good advice although i never had a problem drifting round my local roundabout on the A414 back then. I think I am ok with the statute of limitations on that. I do have a front anti-roll bar and stiffer springs on the rear. Tried to fit a bar on the back but found it did not fit well so rationalised that i didn't need it . Perhaps that is why the pressures seem to work for me, although my roundabout drifting days are admittedly behind me. Alan Quote Link to post Share on other sites
Don H. Posted July 16, 2018 Report Share Posted July 16, 2018 Stan, what modifications did you make to your engine during the restoration of your TR3A? Perhaps your engine is hotter than you realize? My car went back together with 87mm pistons and liners, and a cam with these specs: Intake - opens 20° BTDC; closes 60° ABDC Exhaust - opens 60° BBDC; closes 20° ATDC Duration 260° Cam lift 0.290 in., 0.440 in. valve lift I can chirp the Veredestein Sprint Classic 165/80-15 tires in 2nd gear easily, and almost in 3rd gear. Quote Link to post Share on other sites
foster461 Posted July 16, 2018 Author Report Share Posted July 16, 2018 Stan, what modifications did you make to your engine during the restoration of your TR3A? Perhaps your engine is hotter than you realize? My car went back together with 87mm pistons and liners, and a cam with these specs: Intake - opens 20° BTDC; closes 60° ABDC Exhaust - opens 60° BBDC; closes 20° ATDC Duration 260° Cam lift 0.290 in., 0.440 in. valve lift I can chirp the Veredestein Sprint Classic 165/80-15 tires in 2nd gear easily, and almost in 3rd gear. I rebuilt the motor with 87mm pistons but standard head and cam. lovely torquey engine, will cruise all day at 3000 rpm, 70mph in overdrive 4th. Perhaps my problem is a lead foot. Quote Link to post Share on other sites
barkerwilliams Posted July 16, 2018 Report Share Posted July 16, 2018 Also the road surfaces have been dry and dusty for many weeks now, a decent deluge will clean and improve the adhesion characteristics of the asphalt. Alan Quote Link to post Share on other sites
Colin Fairhurst Posted July 16, 2018 Report Share Posted July 16, 2018 Only teasing Colin Mick Richards Yes I know and I think you are probably quite correct with your various comments. Regarding my earlier post mentioning the possibility of fitting some kind of 'Panhard Rod' to the rear, it was my response to my son expressing concern (he does have an honours degree in motor vehicle suspension design and these are my words not his) about the lateral forces on bends loading up the leaf springs in a way which they are not designed for and if the tyre grip changes at some point in the bend the reaction is like a catapult causing the axle to break away. Regards, Colin Quote Link to post Share on other sites
Graham Harris Posted July 16, 2018 Report Share Posted July 16, 2018 Stan , I have the same tyres and preasures as you and I find it easy to get a chirp on take off if I give her a few too many beans? Graham Quote Link to post Share on other sites
BlueTR3A-5EKT Posted July 16, 2018 Report Share Posted July 16, 2018 Yes I know and I think you are probably quite correct with your various comments. Regarding my earlier post mentioning the possibility of fitting some kind of 'Panhard Rod' to the rear, it was my response to my son expressing concern (he does have an honours degree in motor vehicle suspension design and these are my words not his) about the lateral forces on bends loading up the leaf springs in a way which they are not designed for and if the tyre grip changes at some point in the bend the reaction is like a catapult causing the axle to break away. Regards, Colin For axle sideways location I made up some big thick bronze washers to sit either side of the front spring eye. Revington does a kit that works fine https://www.revingto...r-springs-tr2-4 I located the rear of the spring with solid nylatron bushes from Triumph Tune TT30765 https://www.moss-eur...on-tt30765.html Racetorations do a Watts linkage to locate the axle but that must be for very serious racers, I am assured it works exceptionally well. http://www.racetorat...inkage-kit-p873 Alternatively - you could always remove the rear axle 5 link and watts linkage location system on the Rover SD1 and adapt it to your TR ..... The axle is a sort of TR7 5 speed unit. https://proxy.duckduckgo.com/iu/?u=http%3A%2F%2Fwww.roversd1.nl%2Fsd1web%2Ftechtalk%2Fliveaxle.gif&f=1 Peter W Quote Link to post Share on other sites
Ian Vincent Posted July 16, 2018 Report Share Posted July 16, 2018 My TR3a will chirp the rear tyres pretty easily when Im pulling away. It doesnt bother me. I have 87mm pistons and a 4a spec head and inlet manifold with a 3.45 rear axle. It pulls so strongly from low revs, I could have gone for an even lower ratio back axle. Rgds Ian Quote Link to post Share on other sites
Colin Fairhurst Posted July 16, 2018 Report Share Posted July 16, 2018 For axle sideways location I made up some big thick bronze washers to sit either side of the front spring eye. Revington does a kit that works fine https://www.revingto...r-springs-tr2-4 I located the rear of the spring with solid nylatron bushes from Triumph Tune TT30765 https://www.moss-eur...on-tt30765.html Racetorations do a Watts linkage to locate the axle but that must be for very serious racers, I am assured it works exceptionally well. http://www.racetorat...inkage-kit-p873 Alternatively - you could always remove the rear axle 5 link and watts linkage location system on the Rover SD1 and adapt it to your TR ..... The axle is a sort of TR7 5 speed unit. https://proxy.duckduckgo.com/iu/?u=http%3A%2F%2Fwww.roversd1.nl%2Fsd1web%2Ftechtalk%2Fliveaxle.gif&f=1 Peter W My point was not so much to do with reducing sideways movement of the rear leaf spring, which is what those washers and bushes do, but to prevent the spring from loading up laterally ( sideways ) which can be dangerous. Regards, Colin Quote Link to post Share on other sites
BlueTR3A-5EKT Posted July 16, 2018 Report Share Posted July 16, 2018 (edited) Simple panhard rod then. Single 3/4" diameter aluminium bar tapped 3/8 unf each end with a rose joint screwed in at each end to allow adjustment. The hassle then is attachment to axle one side of the car and chassis on the other. Bracket work is not hard to figure out and measuring after the brackets are in place will get the bar the right sort of length. Plate under spring one side and U bracket on chassis the other. This method works well for the MGB racers. http://www.frontlinedevelopments.com/part/panhard-rod-kit/ Peter W PS More MG reading on Panhard rods and axle traction bars http://mantellmotorsport.com/PanhardKits.aspx Anti tramp bars? http://www.britishv8.org/Articles/MGBRearSuspension.htm These crazy Americans.... http://forum.britishv8.org/read.php?7,1069 Edited July 16, 2018 by BlueTR3A-5EKT Quote Link to post Share on other sites
Colin Fairhurst Posted July 16, 2018 Report Share Posted July 16, 2018 Hi Peter, Thanks for the information. I'll put my thinking cap on. Regards, Colin Quote Link to post Share on other sites
BlueTR3A-5EKT Posted July 16, 2018 Report Share Posted July 16, 2018 Hi Peter, Thanks for the information. I'll put my thinking cap on. Regards, Colin My objection to anti tramp bars or traction rods is the reduction in ground clearance and the fact the a TR has single shear front spring eye connection - Yuk - just like the spring hangers of a Willys Jeep! I have a plan....perhaps mount them above the spring going rearwards? The aluminium bar for panhard rod is under 20 quid to buy plus 2 x rose joints at a fiver each. You could probably use 5/8" dia bar https://www.metals4u.co.uk/aluminium/c1/round/c20/15.9mm-(-58-)/p324 Cheers Peter W Quote Link to post Share on other sites
ianc Posted July 16, 2018 Report Share Posted July 16, 2018 To prevent spring wind-up, the anti-tramp bar needs to be below the spring, but on the TR there is really no room to do this on a road car. Possibly easier to use the springs which were fitted to the Works' TR4 Rally cars, which have 2 leaves running from front to rear, and fit the larger DAS10 dampers. I don't think I've ever had axle tramp on 4VC because the spring doesn't seem to wind up. Ian Cornish Quote Link to post Share on other sites
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