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Learning how to build Lotus Seven replicas...together!
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PostPosted: Wed Aug 06, 2008 9:44 pm 
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Bruce, take a quick look in the Classifieds for a great "jump start" build

So far I am undecided about the manifolds. I was thinking about the TII also. I am still a ways off for that but would love to come across a $10 TII UIM just to check the fits. This is my first forray into the realm of rotary so I am going cautiously. I'm plan on keeping it N/A for now. Another alternative I was thinking about was cutting the lower flange off my UIM and welding 4 tubes up to the plenum behind the standard throttle body. This would put the throttle body on the LH side. I'd also strip a lot of the complication off the throttle body for simplicity sakes but keep it a progressive linkage system.

I was thinking about keeping the 5th and 6th ports. I was thinking about tapping the opposite side of the actuators and using manifold vacuum for actuations. This way I would not need a pump. Could probably be done with a check-alve and an accumulator.

The sump is 1" below the frame. The frame is at 4.5 inches. The sump at 3.5 inches. I don't really want to lower it any more.

Thanks for the reply and please keep an eye open to make sure I don't do anything stupid on the rotary.


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PostPosted: Sat Aug 16, 2008 8:43 pm 
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I haven't got too much to report. I have been reburbishing the braking system. Cleaning- rebuilding and painting. I found that my RR caliper was SHOT!. woa, are those things expensive. $70+ for a rebuilt plus a 40 core. So I got a used one from RX7Club.com on the way. It will have to be rebuilt but I already have the parts. the LR cleaned up very nicely. The clutch slave and master have been cleaned up. I already rebuilt the front 4-pot calipers last year. The std rx7 flex brake lines are on order. Phosphoric acid and a wire wheel clean up the nuts & bolts nicely, don't you think? I have a couple of gallons left over from my home water softening system. It is the main component of metal-prep.

The 2 rear parking brake cables were re-terminated about 2" shorter than normal using a steel rod drilled for the cable and brazed. I had to reattach the termination because the cables were cut when disassembling the car. I don't know if this length will work yet or not. By using the same brazing method, I can shorten the front brake cable to fit (I hope)

I have been trying to fit the '91 RX7 pedals in place, I will have to swap the Clutch and Brake pedals and redrill them for the correct ratio. This will put the 2 pedals about 4-1/2 inches apart. I have decided to use the original style dual master. Mounting the brake and clutch masters will be a challenge as the centers will have to be at 2-1/2 inches which will be a tight fit brcause the Brake M/C's flanges are horizontal while the clutch's are at 45 deg.

The steering wheel assembly is also being considered at the same time. The pedal assy and the steering shaft seem to want to share the same space. More studying of other builds are in the near future.

Oh, I got to test fit a '95 Caterham last week. It was surprisingly comfortable. The steering and brake placement was just about right for my 5'8" body. He had a fixed bench seat and the while the pedal assy was adjustable, he said there was only about +/- 1/2 inch of adjustment available. Its 12" steering wheel had the quick release hub. I definitely will need one of these in my car. All in all a very nice car. He easily cleaned up in his class in the high speed autocross. About 2-1/2 inch ground clearance to the sump of a 2 liter Zetec engine.


Attachments:
brazed brake cable termination.JPG
brazed brake cable termination.JPG [ 68.77 KiB | Viewed 4341 times ]
RR caliper 2.JPG
RR caliper 2.JPG [ 62.26 KiB | Viewed 4343 times ]
RR caliper 1.JPG
RR caliper 1.JPG [ 66.5 KiB | Viewed 4341 times ]
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PostPosted: Mon Aug 18, 2008 10:34 pm 
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Ok , I've spent the day trying to get the RX7 padal assy mocked up in wood before I cut steel. I have come to a few problems.

1st, the pedals themselves are very long. I trying to keep the center of the pedals about 7" off the floor. This makes the pivot high, placing the M/C's high, While they will clear (?) the hood, I fear that the clutch M/C will interfere with the radius of the hood.

2nd, I've tried various configurations of spacers between the pedals and keep seeing problems with the steering column.

I have reverse engineered the dimensions of the Wilwood pedals and can fab a couple up. This will eliminate the right hand curves of the pedals. The 2 pedals would then fall on either side of the steering column. This may not be a bad thing. This will move the clutch M/C inboard. Also, by using the shorter Wilwood pedal dimensions, I can drop the pivot about 2 inches. This should allow the clutch M/C clear the radius of the hood, when I actually get around to making one.

OK, some questions. For those who are using the Wilwood hanging pedals with forward mount masters, how has it worked out for you? What problems did you find and how did you resolve them.

Also, can you take a few shots of your footwell with the throttle pedal in place? I fear that I will be looseing space that would be limiting my options for the throttle.


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rx7 pedal assy.JPG
rx7 pedal assy.JPG [ 63.79 KiB | Viewed 4271 times ]
rx7 pedal assy1.JPG
rx7 pedal assy1.JPG [ 58.6 KiB | Viewed 4275 times ]
rx7 pedal assy2.JPG
rx7 pedal assy2.JPG [ 68.54 KiB | Viewed 4272 times ]
rx7 pedal assy3.JPG
rx7 pedal assy3.JPG [ 59.64 KiB | Viewed 4269 times ]
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PostPosted: Sun Aug 31, 2008 1:50 pm 
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More time passes and more work get accomplished. I have built my own pedals. This has allowed me to lower the M/C’s to an acceptable height that will not interfere with the hood.

I needed to find a new steering wheel so I could finalize the steering shaft angle and lateral and longitudinal location. The donor wheel is way too large. I purchased a 320mm steering wheel / adapter / quick release from e-bay. Cheap at $50 delivered. The steering wheel is good enough quality as is the adapter. The quick release required a bit of re-machining to get the 2 halves to fit acceptably. They mount up well but I will still have to re-engineer the horn button retaining method. It doesn’t want to work and play well with the quick release. What can you expect for $50? In spite of the minor issues, I think it is still a good deal.

I stripped the donor steering system to its most basic parts and started adding stuff as I needed them. I kept the tilt steering capability although it will be set and bolted tightly into place rather than be adjustable while driving. This ended up with a simpler, lighter assembly.

I have come to a decision on my instruments. In keeping with the Locost theme, I have studied the wiring of the donor RX7 and the instrument / switch cluster does require any communication with the ECU. Since the plan was to scrap the ECU and go with the Megasquirt, this seems to be the way to go, at least for me. I mocked up the scuttle in corrugated for test fit of instruments. I found that the dash will have to be more vertical than the book recommendation of 30 degrees. I have used 15 degrees as a starting point. the cahnge is due to the RX7 instruments already being tilted. This will require me to make my own scuttle rather than buying one. This also means that I will have to make the windscreen too. I had hoped that I could use Jack’s parts here, but not to be. I'd like to make the skin of the scuttle removeable for easy access of the wiring. Time will tell if that will be accomplished.

I have redesigned the mounting location of the alternator. In its original position, on top of the engine, it would be sticking out of the hood. I relocated it to the lower LH side of the engine. It will not interfere with the steering shaft and should work well. The downside is that I will have to change the alt pulley to a dual pulley, already on order. The current belt position would interfere with the CAS (crank angle sensor). The good news is that I should only have to run 1 belt, in the forward position, since the contact angle around the water pump is more than 2X greater than it would be with the alt in the original position.

I am unhappy with the fit of the CMC nosepiece in height, and width. As you can see in the photo, the top rail of the frame is ½ exposed on both sides of the nose. Also, the depth of the nose at the front is very short. I will need to add a much larger radiator to keep the rotary cool. I will need a full depth nose to cover the bottom of the radiator. That is in the future. In the mean time, I guess I’ll try to find a buyer who needs a CMC nose.

Next on the list is locating the parking brake lever, connect the steering wheel to the sterring rack so I can actually steer the car, replace the wooden pedal box with something more substantial, and welding up the shortened half-shafts.


Attachments:
tilt - QR steering 2.JPG
tilt - QR steering 2.JPG [ 66.57 KiB | Viewed 4154 times ]
tilt - QR steering.JPG
tilt - QR steering.JPG [ 68.42 KiB | Viewed 4155 times ]
dash -scuttle.JPG
dash -scuttle.JPG [ 57.57 KiB | Viewed 4151 times ]
alternator relocation.JPG
alternator relocation.JPG [ 63.11 KiB | Viewed 4150 times ]
CMC nose depth.JPG
CMC nose depth.JPG [ 57.17 KiB | Viewed 4332 times ]
CMC nose width.JPG
CMC nose width.JPG [ 47.22 KiB | Viewed 4329 times ]
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PostPosted: Sun Aug 31, 2008 3:15 pm 
Hi you are making good progress. Is this CMC chassis basically the same dimensions as "book"?
The problems you are having with the engine height makes me think running a carb like the Dellorto side draft (Racing Beat manifolds) would really simplify things. Like you I think relocating the alternator will help keep the hood low and complete the best "look" of a Locost 7.
I wonder if you leave the LIM on and then make a UIM that would then connect to the standard throttle body. Maybe then you could use all the standard sensors (TPS sensor etc) and the standard engine controller. Should be able to do this without being higher than a side draft carb.

Nice progress. I'm so envious.


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PostPosted: Sun Aug 31, 2008 7:45 pm 
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Thanks for the compliments. I believe that the CMC is just a carbon copy of the book with a few mods of their own and possibly different suspension pick-up points. I'm not 100% sure. I cut out the pickup points and rebuilt the innards behind the rear bulkhead. Everywhere I needed to measure for my build, it was identical to the book.

I have considered the dellorto downdraft but they are $$$$, and don't perform well at lower revs. After mastering the SU's on my MGA, I have thought about the Dellorto more than once for this build. It would keep things simple. But it wouldn't compare to the performance of an injected engine. I figured I would keep the LIM and possibly part of the UIM. The UIM has 2 of the injectors. Then I would come across the top of the engine to the LH side and turn forward. My engine is a S5 6 port and I want to keep the aux ports functional.

My long term thoughts are to build and install a Megasquirt but have also considered the stock controller to start out. Ahh! there are just too many decisions when you design and build your own car. I try to keep as many options open as long in the process as I can.


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PostPosted: Fri Sep 05, 2008 8:51 pm 
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I have completed the redesign and construction of the pedal box. The frame is made of ¾ inch angle and ½ inch angle. This mounts to a couple of 3/4 inch angles welded to the frame so that the assembly can be adjusted fore and aft/ The brake and clutch pedals ar on 4” centers. The clutch is ~ 2-1/2” from the left side. I have reused the RX7 accelerator pedal with some bending. I may have to cut the lower 2 inches off as it gets in the way when my foot goes form the gas to the brake. Left to be done is to weld an outer tube to the brake and clutch pedals and insert the RX7 distance tubes. Also add some return springs to both.

The parking brake is installed. Mounted to an added vertical bracket welded to the tunnel frame and a tab welded to the cross piece at the top of the tunnel. You may notice a temporary piece of twine attached to the hand brake and run rearward to assure that there will be adequate clearance of the brake cable to the driveshaft.

I am still awaiting the tubing to finalize the steering. I’m off the Locost for a few days as I get my MG cleaned and ready for the British Car Festival here this weekend. I hope to see a few Sevens.


Attachments:
pedals.JPG
pedals.JPG [ 55.56 KiB | Viewed 4625 times ]
pedals 2.JPG
pedals 2.JPG [ 163.98 KiB | Viewed 4682 times ]
parking brake.JPG
parking brake.JPG [ 51.67 KiB | Viewed 4020 times ]
parking brake 2.JPG
parking brake 2.JPG [ 59.89 KiB | Viewed 4022 times ]
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PostPosted: Tue Sep 09, 2008 9:58 pm 
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I have completed the splicing of the half shafts. Whether this will be the final version or I will have shafts resplined, I do not know. I do not recommend this to anyone as there are many downsides to modding in this fashion, as has been previously mentioned. For me, I will continue down this road until I have a car running under its own power. Until then, in keeping with the Locost theme, I will spend my money in other places.

I beveled the ends of the shafts about ¼ inch. The sleeve was made using a 3-3/4” long tube, loose fit by a few thousandths. Both ends were cut at 45 deg and 8 holes drilled 3/8” dia. as shown. The 45 degree angle was made to distribute the stress of the welding. The splice was slid to one side during the 1st welding of the 2 halfs. I made an alignment jig using a piece of angle to align the two halfs. In order to get the opposite side in the same position in the jig, I used a piece of the same material cut in half to support it. I first tack welded in 3 places, then welded in 2 passes. The welded joint was ground flush. Any visible voids were V-ground and re-welded. The sleeve was positioned and tack welded in place. Then the 8 holes were plug welded and ground flush. Then I welded the ends circumferentially.


Attachments:
chamfered joint 1.JPG
chamfered joint 1.JPG [ 57.88 KiB | Viewed 3925 times ]
welded and ground shaft 1.JPG
welded and ground shaft 1.JPG [ 54.91 KiB | Viewed 3930 times ]
finished.JPG
finished.JPG [ 51.61 KiB | Viewed 3924 times ]
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PostPosted: Tue Sep 09, 2008 11:30 pm 
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Do you think the sleeve cut at an angle on the ends will cause a balance problem when its rotating.


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PostPosted: Wed Sep 10, 2008 7:46 am 
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Well, I don't think so. The cuts are at the same angle and aligned. Also, the rotating mass of the sleeve compared to the axle, CV's, hub, rotor and tires is negligible, especially when considering that the sleeve is ~ 1/2" from the center of ratation. Also the axle assy will be rotating at a max of 1800 rpm at 120mph. not very fast

I would be more concerned that the 2 halfs of the axle were not aligned causing an eccentric oscillation. In this case, everything seems to be aligned very well.


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PostPosted: Wed Sep 10, 2008 7:11 pm 
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Using the std Rx7 calipers, the parking brake cable brackets at the rear brake calipers interfere with the frame. The photo shows the caliper without the cable bracket before the modification. I found a work around. I swapped the parking brake shafts and return springs L&R between the calipers. This moved the working end rearward and will now clear the rear bulkhead. Then the cable brackets had to be reworked to present the brake cable to the proper location. Also the press-pin in the caliper which the return spring hooks on had to be relocated. All this was done today. I did not get the brackets painted or assembled yet. When I do, I'll post photos.


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PostPosted: Sat Sep 13, 2008 7:39 pm 
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The rear calipers are finished and in the car.

I also finalized the lower coilover mounts.

It gets quite busy under there with the half shafts, the UCA, and LCA along with the parking brake cable, flex brake line and coilover mounts. It would seem that the worse is over in this area. PHEW!

On a lesser note, the new dual pulley for the alternator came in. I cleaned up the alternator and assembled the new pulley. It lines up visually and should work out just fine.

Now on to more stuff.


Attachments:
parking brake mod.JPG
parking brake mod.JPG [ 57.78 KiB | Viewed 3791 times ]
lower shock mount.JPG
lower shock mount.JPG [ 52.7 KiB | Viewed 3787 times ]
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PostPosted: Thu Nov 20, 2008 4:09 pm 
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I'm just about to fall off the first page so I guess it is time to make an update. I haven't been working on the car for a couple of months now. I have been doing some remodeling on the house and the car has taken a back seat. Before I got off the project, I finished up extending the steering shaft by welding up some tubing. What I found out is that the RX7 just above the lower u-joint on the steering shaft there is an elastomeric coupling built in. It is circled in the photo attached. This should slightly dampen any road vibrations that would otherwise shake the steering wheel.

I have purchased a 2-row 2" core Civic aluminum radiator on eBay. For those of you who do not already know, the Civic radiator comes in 2 basic varieties; 1-1/8 " hose fittings and 1.25" fittings. The latter is used on the B16 and B18 series, whatever that means. The former is used on D15 and D16 series. the Civic radiator is considerably smaller than the original rx7 radiator but not as bad compared to the RX8 radiator. The RX8 is 14 x 25-1/4 x 1. The Civic is 13.5 x 16.5 x 2. Hopefully pushing a 1200 pound car will be less work for the radiator than the original car. I am limited in the radiators I can choose from due to using a CMC frame and the associated fiberglass nose. I also purchased a 2000 CFM 14 inch fan for it. Most sellers are listing 12" fans with signifacanly lower CFM ratings for this radiator. The 14" fan should cover 36% more of the radiator so that should help cooling too. You have to start somewhere. Only time will tell if I will need to re-engineer this aspect of the car too.

I have the Megasquirt system on my Xmas list this year. If I somehow get one under the tree, then I can assemble it and test it out over the cold months. I really haven't been good all year long so that might be a stretch.

I hope to spend a little more time with the Locost now that the major part of the remodelling is done.


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steering column.JPG
steering column.JPG [ 67.15 KiB | Viewed 3448 times ]
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PostPosted: Thu Nov 20, 2008 8:21 pm 
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Location: Cincinnati, Ohio
I have that same radiator and I have a 14" fan. The fan I got has flats on two sides and is the same width of the radiator. I did have to notch the top and bottom a little bit. I haven't fired up the motor yet but I am hoping it will keep the motor cool enough. If it doesn't I did see a three core of the same radiator so that that is an option.
Ralph


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PostPosted: Fri Nov 21, 2008 10:21 am 
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From what I have read, some 2 core radiators run cooler than 3 cores. Since we paid "top dollar" for the radiators, I'm sure that they will outperform the stock radiator hands down. :roll: I think you'll be ahead of me on starting the engine. I hope we are both right about the choices we made. I'd be lucky if I get to start my engine by this time next year!


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