What did you do on the rally car today?

Ok the car is basically ready for tall pines. My co-driver wants me to update the computer wiring a little bit and put a horn button on his side of the car so he can use it at spectator areas.

I also get to be really friendly with the tire machine this evening mounting up a new set of hankooks and nokians for Tall pines.

Hacked the other rusty front fender off the Mini, Cleaned up the inners and front panel and sketched up the one missing bit for my replacement lower front suspension arms.

Stock Stuff:


lower arm

tie-bar

Replacements:






The off the shelf bits I've ordered from a circle track place, the custom ball-joint receptacle/rod-end/clevice a friend is going to machine up (along with a few spares) for me.

Any design comments on the funky clevice are welcome and encouraged (I've played with the sketch quite a bit and I think it's sturdy -- but if you see a weak point please LMK) , the two clevices join to form the V of the lower A-arm, and the pin-end of the tie-bar is to be replaced with a rod-end bolted into two weld-on shock tabs.

Changing the length of the tie-bar adjusts castor, length of the lower arm camber.

Cheers, Ted

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Pure mathematics is the enemy of every truly creative man -- Sir Alec

I may be too conservative, but I would go with 3/4" on the threaded part and then use 1"x3/16" wall tubing drilled out to 11/16" ID that could be directly tapped for the 3/4" thread. And how about machining a smooth radius on the edges of the 'ear'; would this be of any use to reduce any stress cracking potential? (And I don't know the loading and associated parts, like the inner mounting bolt's diameter, to make any real good judgement here.)

The clevis's threaded part sure 'looks' weak compared to the original part. But again, persepctive is laking at this end.

Regards,
Mark B.

I like it! I would prefer 4340 over the 4130 for this application, I would also make the thickness of the plate less than the thread diameter and use a nice taper at the area where the thread meets the plate to reduce the stress at the point the threaded area meets the body.

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Boost early and Boost often

Thanks very much guys.

Inner mounting bolt diameter on the lower arm is 5/16" for the OE metallastic bush. The OE pinch-bolt at the junction between the two clevii is also 5/16". The front "tension-nut" on the tie-bar is 1/2". The sphericals are 5/8"x 1/2", and the new pinch bolt goes to 3/8".

The load paths place most of the loads on the threaded sections (both for the two clevii and two sphericals) in "near-pure" tension and compression, there's a little bit of shared load in the funky clevice in a "rock/rut strikes wheel" loading but the majority of that load path leads straight into the balljoint, which has a mean cross sectional area smaller than 5/8".

I'm mostly worried about the ear-tab tearing out or the loss of the cushioning from the rubber pin-mount making a ball-joint shear more likely.

I'm probably overthinking...

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Pure mathematics is the enemy of every truly creative man -- Sir Alec



Edited 1 time(s). Last edit at 11/20/2007 09:56PM by Ted Andkilde.

starion887 Wrote:
-------------------------------------------------------
> I may be too conservative, but I would go with
> 3/4" on the threaded part and then use 1"x3/16"
> wall tubing drilled out to 11/16" ID that could be
> directly tapped for the 3/4" thread. And how about
> machining a smooth radius on the edges of the
> 'ear'; would this be of any use to reduce any
> stress cracking potential? (And I don't know the
> loading and associated parts, like the inner
> mounting bolt's diameter, to make any real good
> judgement here.)
>
> The clevis's threaded part sure 'looks' weak
> compared to the original part. But again,
> persepctive is laking at this end.
>
> Regards,
> Mark B.
Mark,

Hey remember the boys is in a MINI, a REAL Mini not the bloated faux-Mini thing the children think is a Mini, but a real mini MINI, so it weighs maybe max 1550 lbs

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John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

john vanlandingham Wrote:
-------------------------------------------------------
>>
> Hey remember the boys is in a MINI, a REAL Mini
> not the bloated faux-Mini thing the children think
> is a Mini, but a real mini MINI, so it weighs
> maybe max 1550 lbs
>
>
>
Until you climb out of it, then it only weighs about 1400lbs.

LOL, only if I lose 100 lbs Dave. I have a Gerry Marshall physique...

Cheers, Ted

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Pure mathematics is the enemy of every truly creative man -- Sir Alec

Got my circle track bits in, comparison of factory bits to the adjustable stuff, looks like the fabbed clevice will need to be a tad longer on the threaded end.

And I cleaned the garage so the the, gasp, street cars could come inside...

Cheers, Ted

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Pure mathematics is the enemy of every truly creative man -- Sir Alec

I watched John work on my suspension while I asked a bunch of questions, told random stories, and ate a sandwhich. I also attacked the last of the sound deadening with my air chisel, haha.

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Welcome to the cult of JVL drink the koolaid or be banned.

took the broken front spring out of the RallyBuickâ„¢, and took a non-broken one out of a GMC Safari. Same height and diameter, just about 1.5mm thicker wire. Installed the spring, and a new suspender (13.99 from NAPA).

Put 5 gallons of 89 octane gasoline into it (same price as the 87 at the time).

So now, the RallyBuickâ„¢ is ready for the rallyX this coming sunday (12/9).

no dice on finding any sort of good rear end gears, so I'm still stuck with the 2.41 behind the 7004R, stuck behind the Torqueless Wonder 307 V8..

the whole car can be seen here, if you don't know what a RallyBuickâ„¢ is:
http://sharkpork.com/gallery/v/vehick/rallybuick

But, it'll be a blast!!!

Oh, and I reminded myself that I need to calculate what spring rates I need for the SooperBitchinâ„¢ suspenders, but didn't actually do any calculations. John, I'll give you a call soon, hopefully this week, even.

--sarge

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---** To be in compliance with the Anarchy **---
Jorden R. Kleier
Baraboo, Wisconsin, USA
1990 Mazdog Protege 4WD
1973

"Only" 1.5 mm larger wire diameter? Be aware that coil spring stiffness is proportional to the 4th power of the wire diameter. If you went from 10mm to 11.5 mm (with all else being equal) the spring rate would increase by 75% !

Could be interesting! Let us know !

Regards,
Mark B.

starion887 Wrote:
-------------------------------------------------------
> "Only" 1.5 mm larger wire diameter? Be aware that
> coil spring stiffness is proportional to the 4th
> power of the wire diameter. If you went from 10mm
> to 11.5 mm (with all else being equal) the spring
> rate would increase by 75% !
>
> Could be interesting! Let us know !
>
> Regards,
> Mark B.
Mark, your theoretic math is way the hell off.
Way off.
I have gone from 10.5mm wire x coils to 12mm x same coils and the change was nowhere near 70%, more like 30%.

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

Well, the main point was the a seemingly small change in wire diamater will have a significant effect on spring rate and maybe a surprising change in car handling left vs. right. I am curious to know how this car handles with this 'spring-o-dectomy'! Look in the books and check the formulas. If the power I stated was wrong, then I would very much appreciate knowing where I am wrong. In the case where you directly checked rates: Did you assure yourself that all the other factors were exactly equal? Number of coils? EXACT coil and wire diamater? Steel? I've used the basic formulas and gotten good results so have some faith in them.

John, I understand that you would prefer to design by example rather than engineer; that's a fine way to go too. But if some us want to educate oursleves and add another dimension to our car craft abilites, I don't think that is so awfully bad. It does take some time to learn and adjust to the reality factors that useful engineered solutions needs.

In the mean while, why don't you please send me the 2 sets of 2.5" spring perch rings to replace the incorrectly shipped 2.25" ones the we sent back to you about 2-3 months ago? I hate to complain but....

Thanks,
Mark B.

Well, I'm sure there might be a little bit of change in handling, but I didn't even do a test drive yet to find out. It was snowing/sleeting at the time, and I was outside, and I still had to help put tire chains on the truck so we could get back home. I'll put the other spring in eventually, if the car doesn't break this weekend.

I'm just hoping that there are a lot of right-hand turns at the RallyX, lol! It'll probably be pretty crazy, but since I've got a whopping 13.99 + tax (one shock) invested in the car so far, I'm not really worried about it. It was hit in the front hard enough to break the spring, and was/is destined for the junkyard, but I asked my uncle if I could use it to beat on. It lent a whole new meaning to the term "station wagon runs" at the last one in April. we had 5 people facing forward, and one person in the back-back seat facing backwards, then we took a run. the backwards-facing seat is really a treat!!

this is much less a car for actually competing in than it is to re-live what I used to do growing up on the farm, with a '68 Dodge Polara, starting when I was 12 years old or so. cranked the torsion bars up as far as they would go, and it had air shocks on the back, so we jacked those up too. 15" studded snowtires in the back. We had a huge berm in one field that was leftover from when a railroad went through, and I would hit that thing going about 40-50mph, and put any shots from the Dukes of Hazzard to shame! we went through a couple of radiators, and an oilpan or three, but it was way better than this pansy after-school-sports stuff that all the jocks did...

--sarge

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---** To be in compliance with the Anarchy **---
Jorden R. Kleier
Baraboo, Wisconsin, USA
1990 Mazdog Protege 4WD
1973