LOWER FRONT ARMS

[jerome29410]

Hi there,

I am a French owner of a TASMIN S1 ready to restore, picture soon.
I need to replace the front lower arm because they are really in poor condition, many crack around the place of the shock absorber.
Could I use a GRANADA arms instead of the CORTINA MK IV model ?.

[shpub]

No. They are a different size and much longer.

[TOPTON]

I am going to make some of these. Obviously slightly different to fit the ARB but making them is cheaper than buying at £120 a piece.

[grahamw48]

ooooh !

What were they originally intended for ?

[TOPTON]

From Racing Green TVR to fit a Sagaris. Quite easy to make apart fron cutting the big holes for the ball joint. Going to make mine with a solid top and put 2 lugs on the top near the ball joint for coilover mount and 2 holes for ARB bolts

http://www.thetvrshop.com/TVR/Parts/Sagaris/a%7C.h...

[grahamw48]

Great idea.

You may soon have a cottage industry though if they live up to your expectations.

[GV]

TOPTON said:

I am going to make some of these. Obviously slightly different to fit the ARB but making them is cheaper than buying at £120 a piece.

That's a great idea especially to adapt it for use with coilovers....I think you'd get plenty of takers.

[TVRleigh_BBWR]

GV said:

TOPTON said:

I am going to make some of these. Obviously slightly different to fit the ARB but making them is cheaper than buying at £120 a piece.

That's a great idea especially to adapt it for use with coilovers....I think you'd get plenty of takers.

Maybe worth building them to take rose joints, let me know if you need help with all parts required.

[mrzigazaga]

What a brilliant idea..I wish more people could do the same..If had had the machinery and knew what i was doing i would produce parts at good honest prices..Nice one..Zig

[shpub]

Moor racing and others have produced alternative wishbones for the Tasmin series for years but they are not cheap partly because of the amount of work needed to fabricate them. There are a lot of things to consider.

I have built my own wishbones in 2003 and it is a lot more complicated than you first think. There are some pretty strange angles to be reproduced if the tie bar is going to be reused. The length and dimensions have to be absolutely spot on as they will define the camber. As there is no camber adjustment then if that is not right the camber will be out with no possibility of adjustment.

The parts move in quite strange ways and so simplifying the angles will cause issues with articulation as there is insufficient movement to allow them to move correctly.

The ball joints must be angled correctly otherwise they will lock out and break - this has been seen on the Griffith and Chimaera where pattern parts with reduced articulation have broken while driving.

If you rose joint the wishbone be aware that there are tremendous loads on the wishbone. If the bottom is rose jointed then the wishbone will twist and the only thing stopping it will be the shock absorber. As a result, the front tie rod needs to be redesigned to provide the right articulation to prevent the wishbone from twisting. Also bear in mind that the rose joints needed for this can easily cost £50-75 each.

Good Luck.

Edited by shpub on Saturday 22 January 15:18

[grahamw48]

Damm....and I had just started to carve one out of Teak.

[TOPTON]

shpub said:

Moor racing and others have produced alternative wishbones for the Tasmin series for years but they are not cheap partly because of the amount of work needed to fabricate them. There are a lot of things to consider.

I have built my own wishbones in 2003 and it is a lot more complicated than you first think. There are some pretty strange angles to be reproduced if the tie bar is going to be reused. The length and dimensions have to be absolutely spot on as they will define the camber. As there is no camber adjustment then if that is not right the camber will be out with no possibility of adjustment.

The parts move in quite strange ways and so simplifying the angles will cause issues with articulation as there is insufficient movement to allow them to move correctly.

The ball joints must be angled correctly otherwise they will lock out and break - this has been seen on the Griffith and Chimaera where pattern parts with reduced articulation have broken while driving.

If you rose joint the wishbone be aware that there are tremendous loads on the wishbone. If the bottom is rose jointed then the wishbone will twist and the only thing stopping it will be the shock absorber. As a result, the front tie rod needs to be redesigned to provide the right articulation to prevent the wishbone from twisting. Also bear in mind that the rose joints needed for this can easily cost £50-75 each.

Good Luck.

Edited by shpub on Saturday 22 January 15:18

Rose jointing them I think is unnecessary, rubber bushes have managed for 20 years so that's what I will fit. I also think the rubber bushes help with the flex, allowing a little 'give' if required.
Centre of mounting bush to center of ball joint is the critical measurement, that is not difficult to measure. Because as you say, it will alter the camber if not correct.
The angle of the end where the ball joint sits, although important to center the pin, is not critical as there is so little movement. Although getting the correct angle doesn't seem difficult.

Where mine sits now, the arm is parralel to the floor, so the angle isn't really required as it has already knocked the ball joint out of the vertical, so in effect, gets worse as the suspension rises