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Track day Olympic

 
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keith hamer
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Joined: 28 Jan 2006
Posts: 312
Location: Ellesmere Port

PostPosted: Wed Sep 08, 2010 8:59 am    Post subject: Track day Olympic Reply with quote

At the risk of upsetting Jason (I am sure it wont) I have attatched a picture to this post. It was taken at a recent track day which was held at the Anglesey circuit in Wales and shows the car at full tilt with Jason at the wheel.

The car handled extreemly well and showed realy neutral handling characteristics. In the corners we axperienced a little too much roll, but this was put down mainly to the front anti roll bar being off a Morris 1000 rather than the larger Riley item.

The rear end treatment with rose joints on the front of the rear radius arms seems to have worked as we planned it.

Over to you Jason.
http://www.scholar-racing96.com/DSC_0124.JPG
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Paul Gething
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Joined: 10 Feb 2006
Posts: 91
Location: Redditch Worcs UK

PostPosted: Wed Sep 08, 2010 8:44 pm    Post subject: Reply with quote

Nice to see another Olympic out on the tracks...What engine does it run? Rear spring rates and which torsion bars?

Mine is almost ready to get out and about and back on the tracks....too many years....



Will you be doing any sprints or hillclimbs?

A few more modifications on it as well. I am amazed at the amount of competition parts that you can get these days...I always thought that they would be scarce.....Hope to see you at a venue.
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Rodsmith
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Joined: 16 Jun 2008
Posts: 187
Location: Pembrokeshire, West Wales

PostPosted: Wed Sep 08, 2010 9:04 pm    Post subject: Reply with quote

Fantastic! The car is cornering nice and flat, looks like your mods are successful.

Rod
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keith hamer
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Joined: 28 Jan 2006
Posts: 312
Location: Ellesmere Port

PostPosted: Thu Sep 09, 2010 8:37 am    Post subject: PAX 44 Reply with quote

The engine is a mildly tuned 1275 'A' series from a midget, with an Osseli big valve head. The head has big rim flow valves with anti reversion grouves. The botton end has been balanced and built properly. Apart from that the only real thing is the baffling of the sump, which we spent a lot of time sorting out. The carb is a single DCOE 40, and the exhaust is a tubular affair.

In the midget the engine produced a figure of about 80BHP at the wheels, and it has since had the head done. It will willingly rev into the 7,000's and pulls like a little train.

At Anglesey on the GP circuit Jason was doing 1minute 57second laps and there wasn't a car quicker in the corners.

With the exeption of a modification to the front of the rear (phase 2R) radius arms the set-up is almost standard at present. Standard rear spring rates and Morris 1000 torsion bars and anti roll bar.

We now intend to trim the handling by stiffening the front anti roll bar and possibly adding a rear bar so that we can dial in the understear or overstear as required.

We are in some respects using PAX as a test bed for my lightweight which should be out quite soon now. We just need to sort out the perenial problem of Olympic period race history, we have fully documented history for my car but other information is always a bonus.
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Jason Hoffman
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Joined: 06 Jun 2009
Posts: 11

PostPosted: Thu Sep 09, 2010 5:41 pm    Post subject: olympic track day Reply with quote

Had a fantastic day at Angelsey on the bank holiday Monday. The weather excelled itself and my Olympic was great. I am very surprised by the performance of the car,handling and braking. The level of adhesion on 165/70/14 road tyres is very good, under braking the car is stable ,out braking lots of expensive machinery.
The car is a phase 2 but has Riley front suspension,still on lever arm dampers.The rear is standard phase 2 except for modified mountings.
Now we can develope the car and we will be out again in the near future.
Can't wait Exclamation
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Paul Gething
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Joined: 10 Feb 2006
Posts: 91
Location: Redditch Worcs UK

PostPosted: Tue Sep 14, 2010 10:19 pm    Post subject: Reply with quote

"We now intend to trim the handling by stiffening the front anti roll bar and possibly adding a rear bar so that we can dial in the understeer or oversteer as required. "

Oh dear don't fit a rear bar....If you are not running an LSD you will be in trouble. The roll bar will be trying to lift the inside rear wheel and all of your hard earned BHP/Torque will just disappear in a cloud of smoke as the inside rear wheel spins into oblivion.

I fitted one to my Rochdale, couldn’t put the power down coming out of a corner.....took it off and did the float test with it...it sunk so I left it there.

You can see the lugs I put on the axle here....



Just like you, I to wanted to make the chassis adjustable in terms of dialling in and out understeer and oversteer........here follows what I did over a 3 year development period.

My car is a Ph1 with the Riley/MM axle. As I could not afford/justify an LSD I wanted to;
1) Improve traction off the line.
2) Be able to alter the handling characteristics.
After the abortive attempt with the rear roll bar, I took the view that what I wanted was a stable and solid back end that would then give the front an opportunity to do its stuff. I wanted then to be able to trim the front end to get whatever balance I needed. As the front is connected to the rear, what you do at one end will make a difference at the other.

The original rear springs were rated at 85lb/in I carefully measured them and then cut them…shock, horror, heathen…… to turn them into 95lb springs. The car felt more stable and it reduced a little the understeer generated by the skewed roll. So how could I stiffen up the front end?

I found an old FSCC article that stated that Riley torsion bars were 0.75 diameter and that MM bars were 0.78…so I got a pair of MM bars and found that they were 0.82….and fitted them……brilliant transformed the front end and the whole car felt a lot more secure attacking a corner…..But it still rolled far too much………It also wouldn’t change direction quickly enough for a car that has such a low polar moment of inertia.

So I took off the original front roll bar…..it is still buried somewhere in the garage…..and replaced it with a MM trailing link as you can see on the photo.



I then fabricated a half inch 16swg roll bar that was mounted higher than the original and was adjustable in stiffness……..it then was adjusted full on and the car felt awesome….no understeer….very drivable on the throttle…..a great handling car. I then made up further larger front bars with various diameters and wall thicknesses until I arrived at the one fitted at the moment which is 1.125 diameter and 16swg wall thickness….a substantial bit of kit. This was balanced up with 130lb springs on the rear. As you can see from the photo it is not set at full on, therefore I have the ability to adjust the front bar to give me the handling on a given track that I need. I did actually go up to 160lb springs on the rear and adjusted the bar towards further stiffness….but I felt that the rear was right on the edge and went back to 130lb springs and adjusted the front bar accordingly.

If you want me to dig out the actual wheel rates so that you can compare them with you Ph2 then let me know.

Going forward, because I am getting the car ready for next season, I have found out the following on front torsion bars;

Riley 1.5 bars are 0.75 in diameter, from an old FSCC article it states that MM are 0.78, mine off an MM are 0.82….the Morris Minor Centre in Birmingham does ‘uprated’ bars as follows;

50% (whatever that means) 0.785
75% 0.865
100% 0.925

I would like to try the 0.925 springs with the 160lb rears, using the adjustable bar to trim the car.

Just a couple of points;

1) The rear shocks are Caterham 7 with adjustable spring pans and adjustable for Bump/Rebound. You soon know when you have gone over the top on settings.
2) I redesigned the rear suspension turning it into a full 5 link axle with a full width panhard rod
3) The front shock absorbers, lever arm, I have run with very grades of oil to increase their stiffness, can’t remember what is in there at the moment but it is fairly thick stuff….I also took out the valves and wound them up tight…..they still work beautifully…no leaks.
4) I moved the position of the front damper location for a number of reasons.
A) I wanted to get rid of any bump steer.
B) The geometry was giving too much camber in roll. Whilst I had now restricted the roll angle it was still producing too much camber change. By careful measurement and drawings I was able to eliminate the bumpsteer and get the camber change under control in roll. It did produce some camber change in bump and droop, but with the stiffer sprung set up it was not an issue in the ride height range I wanted to run.
5) I am about to change the front suspension rubber bushes for polyurethane bushes which will locate the front suspension even more accurately.
6) I do now run a Salisbury LSD.
7) Next year I will run Yokohama AO48R tyres in a soft compound, 185/60 (6 inch rims) front and 205/70 (7 inch rims) rear. These have very stiff sidewalls and the stiffer springing may get more out of them.
Cool I have fitted Peter May EN24 half shafts to reduce the chance of breakages.
9)Oh yes… the engine…MGB 1.8 with Big valve head, modified by Les Ryder who used to do Bill Nicholsons heads, remember him? 45DCOE, 770 cam (the equivilent of the 'A' series 649), lightened and balanced everything….will pull up tree stumps in the winter….and will outrun most motorcycles down a summers country lane.

It is has been and will be used regularly on the road and during the summer months.

Anyway just a few thoughts and idea’s on some of the stuff that I have worked through on my Rochdale. Twisted Evil
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keith hamer
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Joined: 28 Jan 2006
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Location: Ellesmere Port

PostPosted: Tue Sep 14, 2010 11:15 pm    Post subject: Reply with quote

Well this one should run. Perhaps we need a day at the track to compare notes.
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keith hamer
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Location: Ellesmere Port

PostPosted: Wed Sep 15, 2010 4:55 pm    Post subject: anti roll bars Reply with quote

After reading the sizes quoted for various anti roll bars I decided to measure some of the 7 rochdale olympics currently in our workshop and have come up with the following bar diameters.

3 of the Riley based Olympics have 0.635 inch anti roll bars.
2 others are Minor based and have 0.550 inch bar fitted.

This flies in the face of information already stated in this thread, and I have no idea why this should be, however we seem to have some conformity in the cars measured, hmmm interesting.
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Paul Gething
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Joined: 10 Feb 2006
Posts: 91
Location: Redditch Worcs UK

PostPosted: Wed Sep 15, 2010 7:00 pm    Post subject: Reply with quote

Keith

The diameters in the post are for the torsion bars....not the anti roll bars.

"Going forward, because I am getting the car ready for next season, I have found out the following on front torsion bars;

Riley 1.5 bars are 0.75 in diameter, from an old FSCC article it states that MM are 0.78, mine off an MM are 0.82….the Morris Minor Centre in Birmingham does ‘uprated’ bars as follows;

50% (whatever that means) 0.785
75% 0.865
100% 0.925"


MM and Riley 1.5 didn't have anti roll bars. In fact to quote "Riley Motors Ltd do not approve the fitting of the fitting of these units (anti roll bars). Instead where high speed work is envisaged they suggest the fitting of Morris Minor torsion bars and special shock absorbers".

I have just measured the original anti roll bar that was fitted to the Rochdale and it is 0.635 in diameter. RMP must have had the bars made up specifically for the Olympic......Larger diameter for the 'B' series engine and the smaller for the 'A' series engine.
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