Webbo Posted December 26, 2014 Report Share Posted December 26, 2014 Hi, the FARB on my 1968 13/60 convertible is twisted by about 25-30 mm. Can anyone inform me of an acceptable amount of twist on these things? If this is too much twist , as it seems that the roll bar.is made of mild steel, is it possible to straighten with some heat without adversely affecting the torsional rigidity ? Failing this it seems that only a 7/8 inch dia one is available at Canley , is this an option as I think mine is 1/2 inch? Link to comment Share on other sites More sharing options...
Pete Lewis Posted December 27, 2014 Report Share Posted December 27, 2014 Twister thin ones are quite common and no you dont want any twist at all. the 7/8" bar is fine was used on all later cars I believe there are some thoughts it makes for understeer but having used this bar as an upgrade, find that correct front and rear toe with the (from the manual) 150lb load added to each seat and then setting the toe with the car in in its designed static ride height makes a word of difference . ( does what it says on the tin) Two straight planks and a tap measure is quite accurate enough to measure across the wheels pete Link to comment Share on other sites More sharing options...
Webbo Posted December 27, 2014 Author Report Share Posted December 27, 2014 Thanks Pete, I assume that the 7/8 upgrade is a str.aight forward bolt on with no mods to the mounting Brkts . Link to comment Share on other sites More sharing options...
Pete Lewis Posted December 28, 2014 Report Share Posted December 28, 2014 You need the larger clamps and bushes to suit but the drop links are same pete Link to comment Share on other sites More sharing options...
Webbo Posted December 28, 2014 Author Report Share Posted December 28, 2014 Thanks Pete. Link to comment Share on other sites More sharing options...
Merlin Posted February 10, 2015 Report Share Posted February 10, 2015 Would toe in make any difference to the sag I have on the rear off side. I've changed the spring and trunnions but it still sags. Not by much but it's anoying. I've never seen a GT6 saging and wonder if it could be a torsional thing. Any thought? Peter Link to comment Share on other sites More sharing options...
PJM Stag Posted February 10, 2015 Report Share Posted February 10, 2015 Rear off side of what? Link to comment Share on other sites More sharing options...
Clive Posted February 10, 2015 Report Share Posted February 10, 2015 Which GT6? if non-rotoflex, check both driveshafts are the same length. (late GT6 had a 1" longer shaft, so could cause the issue) Next, it may be a problem at the front of the car Jack the car up centrally front, then rear, see if that helps show which end the problem is. Final suggestion from me. The diff mountings may be bent/out of alignement. A very small amount may cause the issue. Not easy to check either. Link to comment Share on other sites More sharing options...
Pete Lewis Posted February 11, 2015 Report Share Posted February 11, 2015 I Agree, whilst rear toe out will tend to lower the ride and excess toe in will raise the ride its unlikely to cause sag on one side certainly check the front anti roll if you cant jack , try removing one sides drop link. There shoild be no real load side to side.if it springs out of line its bent . Check with a tape the ride height of the front springs let us all knownwhat you find from the clues suggested lean is often nothing to do with where you see the effect pete Link to comment Share on other sites More sharing options...
Merlin Posted February 11, 2015 Report Share Posted February 11, 2015 Sorry I wasn't clear in my post. I've a Spitfire 1500 with a lean on the rear off side. This is noticable from the rear. If I reverse the lean changes to a very upright car with postive camber. I've renewed the spring, using a standard one, and the diff (because of a rumbling sound) and trunions. This made no difference, although it rides better. I'll try out the test discribed and advise. Peter Link to comment Share on other sites More sharing options...
KevinR Posted February 11, 2015 Report Share Posted February 11, 2015 Leans on the rear can be caused by problems at the front and vice versa - usually seized or stiff bushes. Link to comment Share on other sites More sharing options...
thescrapman Posted February 11, 2015 Report Share Posted February 11, 2015 Sorry I wasn't clear in my post. I've a Spitfire 1500 with a lean on the rear off side. This is noticable from the rear. If I reverse the lean changes to a very upright car with postive camber. I've renewed the spring, using a standard one, and the diff (because of a rumbling sound) and trunions. This made no difference, although it rides better. I'll try out the test discribed and advise. Peter If the camber / lean changes when you reverse, that suggests your rear alignment is out. Get a long straight edge, the bottom of the sill is parallel, so you can see if the alignment is out. If one side toes out, it will drag the suspension down on that side when going forward. Reversing jacks teh suspension up. Cheers Colin Link to comment Share on other sites More sharing options...
Pete Lewis Posted February 11, 2015 Report Share Posted February 11, 2015 Yes two good straight bars or plank and tape measure You need 150lbs on each seat before you checkmany geometry so load it , with renta crowd or sacks of coal/sand with the help place the planks against the tyre above the ground bulge and tape measure across the car, use a long plank as said to sight the alignment down the sill. you will get a result in 5 minutes and its free rear toe in static laden is around 0-3mm toe in pete Link to comment Share on other sites More sharing options...
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