tr7triumph.com

I'm curious about the diameter of an uprated anti-roll bar, I believe 30% is usual, if anyone has one they would be kind enough to measure I'd appreciate it.
I believe they are NLA in the UK unless someone can tell me different?
Thanks in anticipation...

Hi Henry,

Rimmers are showing these in stock on their website. £199 - ouch!

Rich.

Cheers Rich, I only found their kits for front and back with all the bushes for an eye watering £ 465ish, didn't look much further there
Had wondered about asking British Springs if they would make a small batch, it would be good to have some idea of the diameter to approach them with, I have a spare standard ARB kicking about somewhere if I can find it

I'm pretty sure the diameters are as follows,

Standard 19mm
Uprated 22mm
Whiteline uprated 25mm

Dave

Dave Dyer wrote: ... the diameters are as follows ...

According to Rimmers site their uprated ARB's are 22,5 mm
My Whiteline front ARB on 't Kreng is 24 mm

Hi Beans, I'll stand corrected on the measurements.
I have a Whiteline bar, it was certainly a lot cheaper than the rimmers. And a massive improvement just fitting that alone.

Dave

Thanks for that Dave and Beans! I'll have a look for a Whiteline before I try elsewhere...

Unless you are an extreme member of the slow in. fast out, don't install an uprated, or heavier front roll bar, unless you plan to match it with a similarly uprated rear bar. Well that is unless you have made some modifications that have induced considerable oversteer in the car.

The action of a front antiroll bar is to transfer weight when cornering from the outside front wheel to the inside back wheel, thus reducing grip at the front, & increasing it at the rear of the car. Thus increasing the front roll bar stiffness leads to understeer. Rear rollbars give the opposite effect.

Exactly the same effect can be achieved with spring rates, & to a lesser effect with shocks. The real advantage of roll bars is that they do it without much effect on the spring rates. Thus you can move the grip around without making the things suspension so stiff it bounces all over the place, except when driven on a billiard table smooth road.

I have 30% stiffer bars on each end of the 7 & the 8, [24mm I think]. This is near perfect on the 7, but if doing it again on the 8, I would have a decision problem. With all it's power, at less than about 7 tenths, applying power merely pushes the front off the road. Applying enough power to stop this by inducing a power slide attracts so much unwanted attention, [law], I just don't do it. At race track speeds it all works quite well.

If I lower the rear grip with roll bar changes I then have that wheel spin problem with any enthusiastic traffic light take off, unless I slip the clutch excessively.

What a long winded way of saying, working at one end of the car will probably induce deficiencies at one end, may be a not expected change at the other end. All modifications should be balanced to work together.

Hasbeen

There can be too much of a good thing. When talking anti roll bars, I'm always reminded of a slalom course in Kelowna my cousin's husband and I went to one year. There was a supercharged Integra (he had put on racing slicks for the event. As the car went around the cones you could see the outside front wheel lift up a couple inches off the ground. It looked strange as it's opposite of what you expect to see. Too much anti roll bar. Despite all the money obviously spent on it, it wasn't particularly fast as you can't get much grip on a front wheel drive car with only one front wheel on the ground. While they had a large timer that could be seen from around the course, there was enough different in speed to tell which cars were fast and which weren't. Fastest was a purpose built Miata with it's drivers (including a young girl) at the top of the timing charts. Biggest surprise was a young kid in a old four door Toyota sedan that looked totally stock. Other biggest surprises were a Porsche and a Mitsubishi sports sedan with a huge wing on back as they kept knocking over cones as they ploughed (literally) around corners at surprisingly slow speeds but I never forgot that over stiff roll barred three wheel Integra.

Dave Dyer wrote: ... I have a Whiteline bar ...

Me too, but sadly no longer listed on their internet site

But again have to agree with Hasbeen though. In my case stiffer springs are fitted front and rear.
Together with decent shocks the car is pretty neutral with a tendency to oversteer.

My car is polybushed all round with slightly stiffer springs and KYB dampers and I really like the way it handles. No issues at all with understeer and the changes of direction and the turn-in is excellent.

Hasbeen wrote: Thus increasing the front roll bar stiffness leads to understeer. Rear rollbars give the opposite effect.
Hasbeen

Whenever I've had to work under the rear of my wedge, I've wondered how effective the rear anti roll bars on our cars really are.


With the live rear axle both ends of the arb are practically moving about in unison. It's nothing like the front where the saddle clamps keep the centre section in place and it twists like a torsion bar. (I'm no engineer)

Looking at the diagram of the rear suspension, it seems to me that the effect of the rear anti roll bar could be increased or decreased by moving it's mounting points further forward or backwards along the trailing arms in relation to the car as this would change the degree of deflection of the bar for a given rise or fall of the wheel on one side in relation to the other. I am no mechanical engineer but this seems logical to me!
Rich.

busheytrader wrote: ... I've wondered how effective the rear anti roll bars on our cars really are ...

Remove the rear anti roll bar and go in search for some challenging pieces of road, and you'll know
I tried it a few years ago and I can only say they really have a purpose there ... http://tr7beans.blogspot.nl/2012/10/a-little-experiment.html
Though a better pick up locations would have made them more effective (or the ARB could have been made less stiff and thus lighter).

Hi Beans,

The rose jointed saddled clamped arb and droplinks in your photo look far more effective than the standard item.

My experimental back to front moment happened when I took my newly converted V8 on to a deserted damp car park.........