Grantura steering gear

[asteinha]

Hi,
from which car is the Grantura MK3 steering gear? Is it from Triumph TR4?

[asteinha]

any help?

[MrPicky]

As far as I am aware the steering on the 1800s Mk III was Triumph Herald (may be the same as the TR cars).

Just to make things more interesting it was mounted upside-down and had a 2 inch bit removed from the middle and welded up to avoid bump-steer.

Have a look at the rack body and see if you can see the ring of weld around it.

Hope this helps.

Russ

[Granturas]

The parts list from the club says Triumph Spitfire MkIII / IV

K.W.

[davegt6]

It is from small chassis Triumph but must be shortened as the rack is too wide for the chassis. Must be done by a competent engineer!

[thegamekeeper]

asteinha said:

Hi,
from which car is the Grantura MK3 steering gear? Is it from Triumph TR4?

In the form that you have the rack it is from a TVR Grantura Mk3. It is derived from a Alford and Alder steering rack which in its original form was fitted with various track rods to many cars.
On the Thurner chassied Granturas it is shortened as part of the design process of the chassis to try to improve the Ackermann angle. This is far too complicated to explain in a PH discussion thread but is basically to prevent one of the steering wheels turning in a different radius to the other causing scrub.This a VERY complicated science because although it is relatively simple to achieve if the wheels were always in the level plane, since the suspension goes up and down it gets 3 dimensional and hence complicated. The most obvious manifestation of this effect is seen when you jack up the front of the car and notice that the wheels both "turn in" as the suspension drops, this causes what is referred to as steering kick back, noticed as a sharp reaction through the steering wheel when you hit a bump. The first thing you try to do to correct this is to have the outer rack ball joints in the same longitudinal plane as the inner wishbone mounts so as suspension rises and falls the steering track rods rotate up or down in line with the suspension pivot points.

With me so far? No? I said it was complicated but the Grantura MK3 was probably much better because of the modified rack in eliminating steering kick back than many later TVR,s.

It is NOT fitted upside down. (I suspect you are confusing things with the LHD steering box fitted to the torsion bar suspended cars). Fitting the rack upside down would result in the steering wheel being in front of the car and digging in the ground!!

A Triumph Spitfire rack will possibly fit with chassis mods but will not work.

The rack from a Triumph is not too long, it is exactly the same overall length as the unmodified TVR rack, the TVR rack has longer track rods to compensate for the shortening.

[Grantura SWE]

The steering rack of my Mk IV 1800S is not shortened (hence there is a terrible bump steer). Was it only the Mk III 1800S that had shortened racks or did my car have the rack replaced post production?