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Lincspeed

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Everything posted by Lincspeed

  1. Here's the last 15 minutes of my first National Race. Car ran great despite very hot weather. Old driver, however suffered a bit... Good soundtrack this time. http://youtu.be/oSmfk6bo8qQ
  2. Here's a video clip of me passing my competition RX7 - actually filling his mirrors and making him miss his braking and turn in point so he goes all 4 off...old age and treachery http://www.youtube.com/watch?v=9PvllizR0FE
  3. Oh Yeah! first victory with this car a couple of weeks ago at our local club track. The new rear suspension has transformed the handling - improving not only rear grip and stability, but noticeably improving front grip and turn in. Off course the new 26lb fiberglass hood has helped too...
  4. We did a three axis data pick on my rear suspension (71 MK III) with stock leaf spring, lower wishbone frame pickup moved 1" lower, and stock upright. Suspension geometry computer program (Mitchell) located the roll center some 4" below the ground. This would explain the excessive body roll in hard cornering-especially with sticky race slicks... My new double A arm rear suspension which moves the roll center around 4" ABOVE ground, corners much flatter with no change in front springs or anti roll bar. Clark
  5. "The Cook..." One of Peter Greenaway's great films with one of my favorite actors, Helen Mirren at her sexy peak...
  6. See, I told you that you are far superior to me when it comes to fabricating. I can't do the simplest type of welding, whatever that is. Pretty impressive stuff there, Steve. Hope it works well for you.
  7. Here's my just completed new fiberglass hood (bonnet). Weighs in at just over 20 pounds, including all the hardware and paint. It consists of three layers of 9 oz fiberglass laid over the original GT6 MKIII hood and final surfaced out with mico filler and a couple of coats of epoxy primer (and LOTs of sanding) I made the wheel houses that attach to the underside out of 1/4" lightweight plywood with one layer of fiberglass on each side and then laminated in place (everything was done with epoxy resins) The finished part is pretty stiff and does not flop around much when lifted off. I did not chose to re do the forward hinge set up.
  8. This topic has been continued on another string of postings : http://sideways-technologies.co.uk/forums/index.php/topic/6429-a-design-problem/page__st__20__gopid__85604#entry85604
  9. OK - got everything installed finally. I had a problem fitting the half shafts back in as there was not w wide enough opening between my upper A arm bracket leg and the shock tower to get the u joint knuckle through. Had to trim and reinforce the shock tower... Anyway, all is in and set up complete. I've put in a bit of anti squat by the spacers on the front upper link (tipping it down in front) and my engineer showed me how to adjust the bump steer, which is done by adjusting the spacers on the bolt through the upper link at the upright. You just rotate the upright around the lower attachment - like a castor adjustment - and measure the deflection in bump. We have it showing only .010 inch per inch of bump measured at two points 20" apart (10" fore and aft of the axel) I will be testing this Sunday at our local track to see how it feels. Clark
  10. Thanks for the translations James and John - GT, I suspect you were a writer for Monty Python - one of my favorite shows, even if I didn't get a lot of the humor... John - yes, the tubing has "flats" on the wide sides so I guess it is "oval". And I think I answered the question about the axis orientation of the lower inboard joints. The rod ends I used can be seen here: http://secure.chassisshop.com/partlist/5431/ they are teflon lined, as are the "monoballs" which are called "insterts" here. Monoballs is the term my engineer used. I believe the Canley part is indeed a monoball/insert, as the cup it sits in looks just like my photo above. Cheers, and Happy Easter to all you Christians out there. Clark
  11. Maybe a fellow Brit can translate "road dirt" and "talk about rocking horse poop" and how they relate to this discussion. I understand the issue GT has about trouble finding good old quality hand presses, but again don't get the relationship to this discussion either. I had hoped for some constructive criticism from Mr GT, as he has provided many times before on this forum. Clark
  12. Well, I must say I feel relieved - "GT" didn't shoot down my design... of course he didn't praise it either. Anyway, the oval tubing my fabricator Dave makes in a die that he machined. He makes 2 sizes 1 is .70 x 1.50 x .049. The other is .70 x 1.75 x .049. Both are made from 4130 seamless round tube. Jay, the engineer/designer says that tests have shown it is stronger than the equivalent round when used properly (as John points out). We used the weld cups and monoball in a horizontal orientation to take advantage of the strength of the oval tubing in that orientation which will carry the loads from the upright. We can accommodate enough suspension travel with this orientation and it is far stronger than a vertical axis on the joint. This is not an off road vehicle with lots of suspension travel... I would also like to clear something else up -Steve, I am sure you are much more "grown up" than I when it comes for fabricating overall. I am just fortunate enough to have a lot of very talented friends to help me with the technical bits. All I'm much good at is sketching up ideas for others to execute. I'll post some assembled shot soon and let all know how this set up works in a month or so. Clark
  13. James, oval tubing was my engineer's rec. He knows best. Eliminated the cross bace when deciding to go to much stronger mono balls rather than rod ends, but yes they are not adjustable, just means the mount brackets must be installed accurately. All the adjustability is in the upper link-even the unnecessary castor, but that allows to compensate for the slight misalignment on the bottom arm. I've got it all assembled and with machined spacers here and there all looks pretty good-we'll see when I do the set up. The horizontally mounted lower mono balls do provide adequate up and down swing for suspension travel. I can improve on that with misalignment washers if needed. Assembly photos soon. Clark
  14. John, I will try to answer your questions - monoball is a term we yanks use to describe a free standing spherical bearing that would be fit into a cup, retained with a snap ring and welded to a suspension component - in place of a normal rod end application which can tend to break under heavy loads at the threads. I have included photos of a cup and the way we used the monoballs on my lower a arms. You can see the snap rings holding them in the cups (which we fabricated from scratch) and the large cup fitting machined out of steel to carry the 1/2" bolt at the bottom of the upright. My design engineer (a very experienced race chassis designer) felt that the loads produced by the GT6 running on 9" slicks with 190HP, should have some very robust attachments. Hence, the 1/2" and 5/8" monoballs on the lower arm. The toe adj. link is also 1/2" (rod ends) all bearings are high strength Auroa pieces. The upper link was cheaper to fab out of billet and will be stronger than welded tube. We used oval tubing on the lower as it is stronger than round. The layout sketch shows the brackets I made and had welded in to the frame. The forward end of the upper a arm is adjustable up and down to effect anti squat. Of course the design relies on coil over shocks and eliminates the leaf spring all together. (makes changing the diff a bit easier!) The resulting geometry gives decent camber gain and gets the roll center about 3.5" above ground as opposed to 4" below ground with the leaf spring set up. And I will have full adjustability of camber, castor and toe. I will take some shots of the installation later, once all is together, but you won't be able to really see what is going on as well as looking at these separate shots.
  15. I don't know if this will help, but this is the final design on my lower a arms - except we changed the inboard joints to captured 1/2" monoball. The fixed outer end of the a arm is a captured 5/8" monoball and the toe adj. linkage is 1/2" rod ends. I have the finished parts and will be installing them next week (along with the new upper a arms) Testing will commence in late April (when the track opens). Clark
  16. My spring (bottom leaf only) arches 3" at rest, and with one foot on it I can flatten it out with probably about 150 lb or so. The interesting thing is that the ends move 1/2" apart which means the camber is changed pretty dramaticly in the wrong way if you see this much movement at the ends of the spring. With my 400lb coil overs on each side, I am seeing about 1.5" bump, so about half that camber change caused by spring "lengthening". This combined with the geometry of the rear suspension produces a considerable degree of positive camber gain in cornering. Not what you want. Steve seems to have dealt with this somehow, at least he feels the car is predictable in racing. I will post my "final solution" once we get design completed. (It does not include any leaf spring). Clark
  17. Just thought I'd add this shot of my MK3 racing front end that I have the mold for. It includes the "bumper" and matches up to the wheels arches (also available) that add about 2" width each side. I made mine in kevlar/fiberglass and it is very strong. The wheel arches are CF and weigh about 1lb each. I mount a splitter to the bottom of the air dam. Clark
  18. Thanks, I guess all I needed was what to call it... found loads of sources right here in the mid west!
  19. Is there a tidy clamp to replace that wonky thing that connects the two throttle shafts? Clark
  20. What is the idea behind the large cylinder? How much does this thing weigh?
  21. Still hoping for a response from GT on my list or questions above....
  22. Actually what I am showing is a wide based lower wishbone w/double pick up on chassis. The extra "joint" on the outboard end of the forward arm I added in to deal with any potential stressing at that point. It may not be necessary - once the geometry is laid out and checked.
  23. I guess I mis interpreted your earlier comments about the leaf spring, and I am having trouble visualizing some of your other comments. BUT, since you seem to have considerable experience in racing GT6's (with IRS, I hope) maybe you could answer some questions so I can better understand. Leaf spring: - what size/rate and what "arch" or offset on top of the diff? -what specific bush at the out board attachment? Coil overs: - using for adjustability of ride hight and corner weights - how do you do this without them? - I am currently using the bottom leaf of a "new" stock MKIII GT6 spring with 400lb springs on the Spax coil overs (this is very common on SCCA Spit racers (Spits run lighter spring rates) Lower wishbone: - mine is the stock casting with rod end fitted to the inboard side for camber adj. I plan to replace it with a tubular part with rod end at all three attachments. Trailing arms (radius arms): - mine are stock. Plan is to fab up new ones with rod ends and either attach to the frame or reinforced body floor points. Is the height of the attachment point on the upright optimum for a lowered race car? Did you ever fit an upper trailing arm to stabilize the top of the upright? Diff: Mine will be solid mounted - it now sits on half thickness stock bushes. How about the rear long transverse bolt ? Engine: solid mounting the engine - did this cause any wear damage (cracking/breaks) to the engine/exhaust or other parts? BTW, my rollcage is pretty extensive and starts at the front suspension towers. Torque testing has revealed little if any twisting... Thanks, Clark
  24. Chris - those are very nice looking pieces. Too bad Triumph didn't go with something like that (with a double inboard pick up) - they look robust enough to stop any toe change or any castor change due to the spring twisting.... but "I'm no engineer" ! We are currently loading all suspension data (front and rear) into a computer suspension analyzing program - like Mitchell, and hope to be able to figure out what to do based on those results. The image i posted is a photoshop retouch of an image or Chuck Pelly's GT6 in Kas Kastner's latest book, with made up suspension links... Re: GT's comment about club racing tires vs. "spec race tires from the "pros" - in the US, club racers use Goodyear and Hoosier slicks that provide typically far better grip than any series spec tire - as shown by lap times run on the same track with both tires, on the same car. These two companies have been in competition for decades to make the stickiest (on most durable) racing slicks for us "club racers". A set for the GT6 or Spitfire cost about $850 US, and the softer compounds will last a couple of race weekends, the harder will last three or more. Of course the more heat cycles, the grip will diminish. They both also make TREMENDOUS rain tires with unbelievable grip - but don't run them when the track dries out! Cheers, Clark
  25. Essintially what I've tried to do was take the "slop" out of the original design leaf spring set up. Controlling the top of the upright has got to be better with this type of attachment than with the spring waggling around from the diff, and the outer end sitting in soft bushings. And moving the effective frame pivot outboard has got to improve the camber change. I certainly would like to add an upper trailing arm, but can't due to the rules. And I would use hard enough springs to minimize overall travel. I admit I had not considered the anti sway effect of the leaf spring, so maybe an ARB would be needed.
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