Setting up front ARB after all was removed

[Jolyon39]

Ok

I had the entire front suspension in pieces, put it all back together minus the locking clamps on the ARB because they were never present on the donor car.

There is a problem, the front RH wheel appears to be too far forward compared to the LH wheel. (Is this what they call caster?)

I will remove the ARB and install the clamps but would like direction on how to align all this.

Jolyon

[Hasbeen]

Not quite Jolyon.

Caster is the action of the front wheel gaining negative camber as it turns inward, & positive camber as it turns outward.

This is caused by the front geometry, where the top of the wheels pivot line is behind the bottom. This can be because of king pin angle, Macpherson strut angle, [like our cars], or the position of wishbones etc. The greater the angle, the greater the caster.

Assuming none of your suspension is bent out of shape your problem is probably that your anti roll bar is offset to one side. The further it is off to a side, the further back that control arm will be pushed.

Measure the wheel base on each side, or from the front wheel centre to the front of the rear wheel arch, to establish the position of the front wheels, then push the bar to the side which is longest to try to correct things.

To put things in perspective, I did discover that a rather poorly handling Brabham I was driving for a bloke was 1 & 1/2 inches longer in the wheel base on the off side than it was on the near side.

It felt much better but was actually only 1.3 seconds quicker on a 1.35 minute lap, after we corrected it.

Hasbeen

[Beans]

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Jolyon39</i>

...the front RH wheel appears to be too far forward compared to the LH wheel ... <hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">
Move the ARB to the right to rectify this.

<font size="1">edit ... Hasbeen beat me with his reply</font id="size1">

<center>
<font color="blue"><i>1980 TR7 DHC (my first car, now restored and back on the road)
1981 TR7 FHC Sprint (better known as 't Kreng)</font id="blue">
<b>[url="http://www.tr7beans.blogspot.com/"]<u><b><font size="2"><font color="red">My Weblog</font id="red"></font id="size2"></b></u>[/url]</b></i></center>

[Hasbeen]

Beans, not only was I first, I used a lot more words, to say basically the same thing. So I win.

Hasbeen

[Jolyon39]

Thanks, just as I thought! The guy at the wheel alignment shop was certain it could not be adjusted.....

Jolyon

[Beans]

OK Hasbeen, you have won yourself a pint of good Belgian beer.
Collection in the Netherlands only [:D]

<center>
<font color="blue"><i>1980 TR7 DHC (my first car, now restored and back on the road)
1981 TR7 FHC Sprint (better known as 't Kreng)</font id="blue">
<b>[url="http://www.tr7beans.blogspot.com/"]<u><b><font size="2"><font color="red">My Weblog</font id="red"></font id="size2"></b></u>[/url]</b></i></center>

[Jolyon39]

Hi,

Just to make sure we are talking the same thing.

Here is a copy of the wheel alignment report:





Do I have to go back to the alignment centre and explain that they need to move the ARB.... is this correct?


Jolyon

[Hasbeen]

Jolyon there can't be much wrong with your wheel position with those caster figures. Unless the thing is very bent a wheel being forward would have to give you bigger errors than that.

Your rear axle is further out than your front, & it's not enough to have any effect.

How does the thing drive? is it tracking reasonably straight, or drifting just slightly left with the camber of the road? If so I'd be happy with it as is. Just fit the clamps to stop it changing.

Back a while our Fords used to have bent rear housings, [from the factory], & lousy location of the thing on it's cart springs. WE used to set them up much further out than that, side to side, to try to stop them pulling into the oncoming traffic, or up the gutter.

The worst ones would pull left on the over run, but right under throttle. It was impossible to do anything much with them, except to make sure you didn't own one of them.

Unless yours is doing something silly, it is probably not worth mucking with, even for a pedantic coot.

Hasbeen

[Jolyon39]

Hi Hasbeen,

It steers and corners well,... so much fun to drive.

Problem:

The RF tyre hit the bottom front tip of the guard when I reversed out hard from the alignment bay. I sung out to the LHS with the car ending up 90 degrees to its original position.

Anyway, the hit was noisy and a problem. There is evidence of very poor quality panel beating in this area of the shell (Badly fitted new guard) so maybe the guard is too close. Butttt I had hoped that just a couple of degrees on the ARB fix it.

I could just cut the bottom tip off the guard!

Here are photo's of the gap on the LHS and the RHS with the wheel turned. (I am about to buy 15" tyres, should I stick to 185's with this problem?)

Will 3 to 5 degrees fix this prroblem?

Drivers Side


Passenger Side (LHS)




Jolyon

[PeterTR7V8]

Mine will rub on the rear of the inner guard when the wheel is turned & the car is reversing. There is a bit of a ledge there & I've given it the bash to flatten it out which has helped. If you are rubbing on 13" wheels you are bound to find 15" wheels very "rubbery" but the overall diameter is what counts so go for a lower profile tyre. Mine are 205/50R15s on 7" rims so anything less should fit easily.

Good to hear you are driving the car at last.



The map: http://tinyurl.com/wedgemap . The blog: http://www.forum.triumphtr7.com/topic.asp?TOPIC_ID=8548

[bmcecosse]

I don't see anything much wrong with these figures - within manufacturing tolerance I'm sure! Any 'rubbing' is more likely to be due to incorrect wing position. I do however strongly recommend fitting the 'anti dive' kit (I made my own) to the front arb. Does absolutely nothing to prevent 'dive' - but helps the turn-in a great deal!

[Jolyon39]

Hi Peter,

Thanks for the tyre info, I have 15" MGF rims here and they really make the car look good, need to find wheel nuts to suit though

No WOF or Rego yet, just ironing out the bugs. Teething probs because the car was in so many tiny bits.

As you know, I live rural so it was easy to drive around here..... until yesterday when the Police turned updue to complaints about the step sons driving. Now they are watching this place!



Jolyon

[Jolyon39]

Hi bmcecosse,

Thanks for the comment on the anti dive kit. I will most likely make one up but only install after the car has its first safety test in 14 years (we have to have them tested every 6 months here). I want everything on the car to look standard so they just get it tested and back on the regular road register. I think the UK term is SORN and this car has been SORN for 14 years, well the serial number tags have been SORN for 14 years.


Jolyon

[saabfast]

I had exactly the same problem after rebuilding my front suspension. It had seemed fine before, although I had only driven it down a lane to try and onto a trailer to get it home. Mine does have the clamps ('81 model) but it still seemed to change. Measurement showed the left hand wheel was not as far back as the righthand.
I initially trimmed the corners of the front wings where you are pointing into a neat radius (did both sides to keep it neat and incase any MOT inspector objected).
I then took Beans suggestion and slackened the clamps and wacked the ARB from the right side with a large nylon faced hammer (still ruined the nice new paint finish). I had to hit it VERY hard to get any movement but it did move the left wheel back a bit, enough for me to stop worrying that the thing was way out even if not quite equal.

Alan
Saab 9000 Stg 1
Saab 9000 2.3 FPT Auto
'81 TR7 DHC