Installing Wheelie Bars

Blue · Post by **Blue** » Tue Oct 09, 12 6:51 pm

I have no experience but theres a bunch of info here...
http://www.dragzine.com/news/wheelie-ba ... ning-tips/

Cannonball · Post by **Cannonball** » Tue Oct 09, 12 9:53 pm

thats bloody brilliant blue.. so pete needs a 50" bar,

the sort of detail i reckon most people with wheel bars dont bother with.... thanks

Pete · Post by **Pete** » Tue Oct 09, 12 11:11 pm

Thanks chaps, won't get them on before the weekend, though...........

Les Szabo · Post by **Les Szabo** » Wed Oct 10, 12 8:22 am

If all else is done apart from the wheelie bars, it'll be good to get a base on the car Pete?, just tighten your front shocks up 80/20?, limit fr/end travel, have your l/bars 2>3 deg down, bottom hole?.....and run your rear tyre pressures high till it spins just a little, then back off, thats a good base set up to keep her down, tune from there, sounds easy doesn't it............

Doubt if a RWYB track will be that good that you'll rear bumper the car anyway.

Les

Anonymous · Post by **Anonymous** » Wed Oct 10, 12 9:14 am

Pete, my original point was that nuts and bolts are designed to work in compression but the way you are mounting the bars you will load your fixings laterally AND you will be putting a rotational force on them which on one side will try and loosen the nut and on the other, tighten it. So, the former will lose pre-load and fail in fatigue and the latter will over stress the bolt and it may fail from fatigue .

THAT is why I went to such length to describe the importance of fixing choice. I did do it for a reason mate. I am far from stoopid in this particular area.

Oh, and while I'm at it. Philidas torque prevailing nuts are what you want (or you can use what everyone else in the pits use - but we've moved on a bit since the 70's

) Just be careful matey, thats a serious machine you are beasting up that 1/4

Pete · Post by **Pete** » Wed Oct 10, 12 9:18 am

I think you are correct, Les.
We just need to get it to the track to see if it drives straight and which bits fall off.

I do not think there will be any heroic launches at this time, we will save the trans brake for another day.

I am still concerned about front end height so we need to make sure we do not kipper the sump.
The car does seem low, but the Torsion bars are much more tensioned than I have done on previous cars and there is a lot of clearance between the chassis and LCA bump stop, again something that is new to me.

Normally I run about 1/4" gap at ride height.............at the moment it is over 1" and the sump is still very close to the ground and the clearance needs to be Greater- and that is with the "K" frame spaced off the chassis as well

Pete · Post by **Pete** » Wed Oct 10, 12 9:25 am

Thanks Clive. I do appreciate the input.

All Wheelie bars apper to be designed so the bolts are in sheer condition.
I do not actually think they will take a lot of load.
As Ivor points out, the top ones (which are usually pins anyway) take most of the load.......

Not going on for this weekend anyway - as usual we have fallen behind schedule and had to prioritise the key areas for attention............

Incidentally, all the Competition Engineering Ladder bar fixings (the BIG Bananarama!-off ones) are Nylocs....food for thought...........

db · Post by db » Wed Oct 10, 12 11:02 am

All rod-end mounted chassis components are designed to be mounted with bolts in the 'shear' position. My S&W 4-link with QA1 coilovers is all mounted with bolts in the shear position and all with nylocs. If you check out the Chassisworks site their kit is the same and as Pete says, all ladderbars are designed this way.

Sorry but I gotta disagree with you Clive (though I know I'm about to get shot down in flames

) Bolts ARE designed to be used this way aswell. They have a shear rating (which obviously will be less than the compression rating), you just have to ensure your application doesnt exceed this.

BTW, I've used nylocs for 30 years on bikes, mainly buzzy 2-strokes, and have never had one work loose. Maybe i'm just lucky?

Anonymous · Post by **Anonymous** » Wed Oct 10, 12 11:45 am

db wrote:All rod-end mounted chassis components are designed to be mounted with bolts in the 'shear' position.
Sorry but I disagree with you Clive (though I know I'm about to get shot down in flames )Bolts ARE designed to be used this way aswell. They have a shear rating (which obviously will be less than the compression rating), you just have to ensure your application doesnt exceed this.

?

Mate, of course bolts have a shear rating, but where a bolt is used in a horizontal (for want of a better expression) position, the bolt in full preload puts a compressive force between two surfaces and it is THAT clamping force between the two surfaces which you rely on to resist shear - not the bolt alone. Bolts arent designed for that.

I could bore you to tears about bolted connections mate. Really.

Pete · Post by **Pete** » Wed Oct 10, 12 11:51 am

Impressive, Clivey; and not one Knob gag either

Les Szabo · Post by **Les Szabo** » Wed Oct 10, 12 12:08 pm

Pete your runners are quite low profiles.....try some old school 28" tall drag tyres time permitting, should be ok w/chassis hdrs?, or just take a wide line to the return road

....Either that or its out wide and down straight with the sump for your line connections if you wanna continue to run 8qts with NO tray.

Anonymous · Post by **Anonymous** » Wed Oct 10, 12 1:16 pm

I have to say though, Paul has a particularly attractive 'rear end'.

Love looing at the stuff you racers build. Impressive stuff.

It would be interesting to calculate the forces a car like that puts around its structure on a full tilt launch.

I bet a Finite Element Analysis produced some interesting data. getting the front end of a front engined car up is an impressive feat.

shovelheadrob · Post by **shovelheadrob** » Wed Oct 10, 12 2:58 pm

If you want to try complicated calculations, try to work out the forces generated during tyre shake, we have had 3/4 unf bolts that have been torqued up correctly come loose & I have seen chrome moly tube chassis' crack from it (not around a weld either).

autofetish · Post by **autofetish** » Wed Oct 10, 12 2:58 pm

might help

Pete · Post by **Pete** » Wed Oct 10, 12 3:01 pm

I think you will find that came out of a car park at Asda