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Watts Link Bracket Clearance

PostPosted: Sun Nov 19, 2017 5:21 pm
by MK1_Oz
I did Targa High Country last weekend and managed to bent the Eurosport (Eurospeed? - cannot remember) watts link bracket. It hit the ground going through a dip onto a bridge resulting in the lower section bending backwards. TBH it didn't seem to effect the car handing a massive amount although it did feel a little squirrely. My size 10's had no chance of trying to straighten it up so I had no choice but to continue.

From the boot floor to the bottom of the triangle bracket is 260mm. The bell crank's lowest edge sits maybe 5-10mm higher but there is scope to play with the roll centre and raise this (I have never bothered playing as there are other things to sort before refining the suspension tuning).

How low do other's watts link brackets hang? I remember that Danny uses some lovely looking CNC billet thing that I recall being smaller. Could be wrong. JP uses the same bracket as me and his looks to hang low too. Think Roger may have used an ex-v8 tourer one with wind up/down roll centre.

I use 275/180lb springs and bought some slightly harder ones but never fitted them. They may help to keep the important bits off the ground!

Re: Watts Link Bracket Clearance

PostPosted: Mon Nov 20, 2017 6:08 am
by jpayne
My triangle can be mounted higher on the crossmember, I have an extra row of bolt holes and gussets in the 'beam' that align with the bolt holes below those shown to be used in the most recent photos. This brings it up about another 30mm. Ill admit while its on the trailer it doesn't need to have been assembled properly
I am using the smallest triangle available from that manufacturer. as in the photos its about in line with the bottom of the diff. there is 50mm of travel left before the bump-stops are compressed so the triangle will always be a bit low unless I trim it. I can raise it up further with new holes or a new triangle design. pretty simple water cut sheet aluminium.

Others' all seem a similar dimension. a fact is the pivot and diff centerline relationship means they all need to be similar depths.

JP

Re: Watts Link Bracket Clearance

PostPosted: Mon Nov 20, 2017 10:08 am
by MK1_Oz
And of course the bell crank thingy will always need to be where it needs to be for the desired roll centre.

Raising up the crank generally does what to the handling???? More hours doing research........

Re: Watts Link Bracket Clearance

PostPosted: Sat Dec 02, 2017 10:22 am
by Danny M
How bent is it, have you got a photo?
and how much suspension travel have you got and is it bottoming the bum stops out

Re: Watts Link Bracket Clearance

PostPosted: Sun Dec 03, 2017 5:10 pm
by MK1_Oz
Will post something when I get get in the shed to take a pic....

Re: Watts Link Bracket Clearance

PostPosted: Sat Apr 21, 2018 7:20 pm
by MK1_Oz
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Finally got into the shed to look at the car. Few pics attached.

Looking at the bell crank, it only appears to have scrapped the ground from about 10mm from its base so it has taken the edge off the crank but has not ground into the bolt hole. No need to replace it. You can see the amount of bend in the brackets (I have spares sat next to me ready to install).

The way I see it there are several approaches I can take to make sure this doesn't happen again and to make sure it is not constantly in my mind whilst driving;

    modify the new triangle brackets so that when the bell crank is mounted in the same holes it is higher off the ground = raising rear roll centre
    raise the bell crank in the brackets = raising rear roll centre but still leaves the brackets hanging low
    raise the rear suspension
    fit firmer rear suspension springs

This is a link to footage of me in Targa High Country. Inside the car it feels like it is rolling massively and maybe the footage shows this? https://youtu.be/83JYL72Wdu4 The car feels very planted on corners with a hint of understeer when pushed hard. It is hard to get the back end out.

What are your thoughts? I have NEVER played around with the roll centre/watts and am totally guilty of selecting a random hole when I built the car and I have never changed it. I also have never played with spring rates. I have 275lb fronts and 180lb rears although when I corner weighed the car it was almost exactly 50:50 front/back and side/side so shouldn't the rear springs be a little heavier?? No rear ARB and 22?mm front ARB. I realise the weight moves forwards under brakes hence the additional spring rate on the front. The current spring rates were suggested on both the Turbosport forum and this forum. I have bought new springs at 375/225 but am very hesitant to try them - I don't have the luxury of using the car during the year so my testing is done on the one event a year that I do.

My current thinking based on the theoretical research I have done is to put the 225lb springs in the back and raise the watts bracket and bell crank up 10-20mm to be sure that it will never hit again. The effect on handling would seem to be that I will have a little more oversteer?

Re: Watts Link Bracket Clearance

PostPosted: Sun Apr 22, 2018 7:24 am
by jpayne
I have often derided the english preference for the twin tower watts with fixed centre welded to diff but this must be a safer 'rally' setup as the wheels would still protect the on full bump to a degree...of course dipping a wheel of the edges of roads puts them into strike range.
watts pivot wants to be centred on the diff at the mid point of actual not theoretical travel. then add roll centre adjustment. Hopefully that puts the pivot high enough to trim the tower bracket and add extra clearance.

JP

Re: Watts Link Bracket Clearance

PostPosted: Sun Apr 22, 2018 6:03 pm
by jpayne
Of course thinking about it overnight. Its the bell thats the lowest bit. Not the bracket but bell that struck, so doesn't really matter how short the bracket can be.
What did it handle like bent?
JP

Re: Watts Link Bracket Clearance

PostPosted: Sun Apr 22, 2018 7:00 pm
by MK1_Oz
jpayne wrote:What did it handle like bent?
JP


Surprisingly I felt little difference. Maybe the car felt slightly less settled but it was never an issue. The bell crank is currently around 2" lower than the diff centre. Will raise it all up and just have to see how it goes. I am trying to get it Rally Rego'd so I will have a small opportunity to drive it on the roads which may or may not highlight a handling difference.