Bump steer - best solution
Discussion
I have not put larger tyres on yet (but will when they wear out) I have had a look at the geometry of the front suspension/rack and arms and as the front wheels move up and down you can clearly see a curve motion over the full travel. Once this is fixed I'm sure pot holes etc wont have me fighting the steering wheel anymore. Someone must have sorted this problem out by now!!
I made a set of modified steering arms for my T350. Used 2 sets of standard flat arms with some fabrication work to make something which looks like an inverted Sag arm - but with the step to the track rod end down instead of up. The track rod end then remains in the down pointing position as in the normal Tam, T350, Tuscan installation. That drops the end of the arm by about 15mm.
One other tip is if you buy Quinton Hazell Rover SD1 track rod ends they have the correct thread (M14 x 2.0) and taper but sit about 5mm lower as the taper pin is closer to the centreline of the steering arm.
Combination of the two gave steering arms which are nicely parallel with the lower wishbone.
Word of caution - MIG welding isn't man enough for this, you need some real heavy duty arc welding to get it strong enough. I tacked the brackets up and took them to one of our contractors who does certified welding. Will post some photos.
Extra sets of the straight arms are available new still, or I bought a set of used ones from TVRdean.
And obvious point but you need to reset the tracking properly.
C
One other tip is if you buy Quinton Hazell Rover SD1 track rod ends they have the correct thread (M14 x 2.0) and taper but sit about 5mm lower as the taper pin is closer to the centreline of the steering arm.
Combination of the two gave steering arms which are nicely parallel with the lower wishbone.
Word of caution - MIG welding isn't man enough for this, you need some real heavy duty arc welding to get it strong enough. I tacked the brackets up and took them to one of our contractors who does certified welding. Will post some photos.
Extra sets of the straight arms are available new still, or I bought a set of used ones from TVRdean.
And obvious point but you need to reset the tracking properly.
C
I made a set of modified steering arms for my T350. Used 2 sets of standard flat arms with some fabrication work to make something which looks like an inverted Sag arm - but with the step to the track rod end down instead of up. The track rod end then remains in the down pointing position as in the normal Tam, T350, Tuscan installation. That drops the end of the arm by about 15mm.
One other tip is if you buy Quinton Hazell Rover SD1 track rod ends they have the correct thread (M14 x 2.0) and taper but sit about 5mm lower as the taper pin is closer to the centreline of the steering arm.
Combination of the two gave steering arms which are nicely parallel with the lower wishbone.
Word of caution - MIG welding isn't man enough for this, you need some real heavy duty arc welding to get it strong enough. I tacked the brackets up and took them to one of our contractors who does certified welding. Will post some photos.
Extra sets of the straight arms are available new still, or I bought a set of used ones from TVRdean.
And obvious point but you need to reset the tracking properly.
C
One other tip is if you buy Quinton Hazell Rover SD1 track rod ends they have the correct thread (M14 x 2.0) and taper but sit about 5mm lower as the taper pin is closer to the centreline of the steering arm.
Combination of the two gave steering arms which are nicely parallel with the lower wishbone.
Word of caution - MIG welding isn't man enough for this, you need some real heavy duty arc welding to get it strong enough. I tacked the brackets up and took them to one of our contractors who does certified welding. Will post some photos.
Extra sets of the straight arms are available new still, or I bought a set of used ones from TVRdean.
And obvious point but you need to reset the tracking properly.
C
it was pretty easy to remove the track rod ends on my griff, and replace with automotive spec rose joints. drill the steering arms to take m14 bolts, and then you can shim the track rod ends to wherever you want.
on the griff, i achieved NIL measurable bump steer over plus 2 inches, to minus 2 inches. before shimming properly, i could easily measure bump steer.
of course, if the rack itself is too short (or long) at the pivots, you will end up with a compromise, and increase the rack height to accomodate may also be necessary
on the griff, i achieved NIL measurable bump steer over plus 2 inches, to minus 2 inches. before shimming properly, i could easily measure bump steer.
of course, if the rack itself is too short (or long) at the pivots, you will end up with a compromise, and increase the rack height to accomodate may also be necessary
SteveSPG said:
snippity............of course, if the rack itself is too short (or long) at the pivots, you will end up with a compromise, and increase the rack height to accomodate may also be necessary........snip
For Tamoras and possibly T350s, some early cars have/had the "short" racks WRT the pivot point and raising the rack does help.One of the main problems is when aftermarket rims in different widths are fitted, which invariably adds to the problem of bump steer with an incorrect ET.
Trev
GTRene said:
I also read many (if not all) test drivers in the old days of TVR complaining about the bump-steer in the older cars, why did TVR not find a solution for that...is it so hard to do?
They did, with the Sagaris.I'm not 100% on the technical side of this but I think Str8Six's bump steer mod uses Sagaris steering arms and adjusts the height of the rack. I have it fitted, it works well on my T350.
Targarama said:
They did, with the Sagaris.
I'm not 100% on the technical side of this but I think Str8Six's bump steer mod uses Sagaris steering arms and adjusts the height of the rack. I have it fitted, it works well on my T350.
Str8Six won't sell it's mod, you have to go to them to have it fitted. I believe it's the reason I touched upon, in that not all T cars have the same racks.I'm not 100% on the technical side of this but I think Str8Six's bump steer mod uses Sagaris steering arms and adjusts the height of the rack. I have it fitted, it works well on my T350.
It's probably the reason a "re-call type solution" wasn't undertaken by TVR and why Str8Six want to control fitment as sometimes they have to change the rack - not a cheap solution!!
TADTS doesn't apply to bump steer. It really is hit or miss on whether your T car has it or not!! (and if you change your wheels for non OEM, you "may" introduce it, IMHO)
Trev
I knoww the t car pick up points for front uprights on a tam, tuscan and t350 were amended, and use different wishbones, but are they in the same alignment as the old positions fore to aft...ie if you had both old and new on the same chassis, would a dowel align them ??
I know the spring mouintS are different, but if tvr used the same rack, it would suggest that they maybe in a similair alignment.
Just curious really...
I know the spring mouintS are different, but if tvr used the same rack, it would suggest that they maybe in a similair alignment.
Just curious really...
craigcaf said:
Some photos of the bump steer mod on my T350
Regarding the Str8six Sagaris steering arm mods - I believe that although this is advertised on their website, they have no stock of the steering arms anymore - at least that's what they told me.
C
Correct they don't do it anymore, plenty of other ways to reduce it although mine had no issues here Regarding the Str8six Sagaris steering arm mods - I believe that although this is advertised on their website, they have no stock of the steering arms anymore - at least that's what they told me.
C
Edited by ShiDevil on Thursday 28th February 21:12
craigcaf said:
Some photos of the bump steer mod on my T350
Regarding the Str8six Sagaris steering arm mods - I believe that although this is advertised on their website, they have no stock of the steering arms anymore - at least that's what they told me.
C
Did you measure the before and after?Regarding the Str8six Sagaris steering arm mods - I believe that although this is advertised on their website, they have no stock of the steering arms anymore - at least that's what they told me.
C
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