MV8 Posted July 8, 2023 Share Posted July 8, 2023 Springs definitely settle/sag and new springs are more likely to do so, including oem springs. It is not unusual to have one settle while the other does not, despite being the same age, number of cycles, and batch. Oem spring replacements usually come as pairs that are matched. Used springs are less likely to sag/settle. Coil diameter is also a reliability factor. The wire twists in operation. Link to comment Share on other sites More sharing options...
Yoram Posted July 17, 2023 Author Share Posted July 17, 2023 Bathroom scales work! Back from a few weeks up north. Today was the first test of whether my Amazon bathroom scales will survive the weight of the empty car, and especially the transition when rolling onto the scales. So I crossed my fingers and rolled the car onto the scales, first with the fronts only (dummy scales at back) and then with all four wheels. No issues! All four scales supported the load intact and recorded consistent readings. I rolled the car on and off the scales several times to confirm. Having confirmed that the scales survive, I used my siphon system to shim them to ensure each axle is horizontal: Left front was ~5 mm low -- required 3 vinyl tiles, and left rear was ~7 mm low -- 4 tiles. Current corner weights before any adjustments and without engine oil or coolant, seats, cat+muffler, wings and lights are: LF=270.6, RF=279.2, RR=255.6, LR= 274.0 [lb] Next steps will be to roll the car off the frame, load with ballast, roll back onto the frame, adjust ride height and cross weight, and then torque the suspension joints. Siphon system for leveling the scales: Car off scales: Car on scales: Typical reading: Cheers! 1 Link to comment Share on other sites More sharing options...
Yoram Posted July 17, 2023 Author Share Posted July 17, 2023 (edited) Re Spring Settling My plan is to set the ride height up a bit on the high side, maybe 170 mm front and 185 mm rear with target load, and check it after a few hundred miles. I now have my ultra high tech ride height and cross weight adjustment system which I will keep for a while... Will report developments... Edited July 17, 2023 by Yoram Link to comment Share on other sites More sharing options...
Yoram Posted July 17, 2023 Author Share Posted July 17, 2023 (edited) Correction to Next Sequence After some more nagging thoughts I decided that torquing the suspension joints/bushings should be done at "curb" ride height, which is the target ride height at curb weight (and which Caterham does not specify...). My interpretation of curb weight is empty car with 1/2 tank of gas, ready to be stepped into, started and driven. The reason for this decision is that the bushings on a Seven spend at least 98% of their life in "curb" ride height... (in garage) Therefore, I am now proceeding to load the car as close to "curb" as practical, roll it back and forth, set the ride heights and cross weight under that load, roll it back and forth again, verify the ride heights and cross weight, and torque the suspension joints in that position. This will include simulating the weights and positions of the heavier parts which are not yet installed, such as the exhaust downstream of the header pipes, seats, etc. Then I intend to load it up to "nominal" driving weight -- me, half of my better half (splitting the difference between 1 and 2 up), small bag in the trunk. I will then roll it back and forth again and check and if needed adjust the cross weight one more time to 50%. My OCD has now kicked into overdrive. More soon... Edited July 18, 2023 by Yoram Link to comment Share on other sites More sharing options...
KnifeySpoony Posted July 18, 2023 Share Posted July 18, 2023 why not just wait to torque the appropriate fasteners after the car is complete? 1 Link to comment Share on other sites More sharing options...
Yoram Posted July 19, 2023 Author Share Posted July 19, 2023 On 7/18/2023 at 1:30 AM, KnifeySpoony said: why not just wait to torque the appropriate fasteners after the car is complete? Because access is more difficult with the wings and seats in place, and wings are vulnerable with all the shuffling and wrenching around them. Link to comment Share on other sites More sharing options...
MV8 Posted July 19, 2023 Share Posted July 19, 2023 The goal is to minimize the degree of twist with bonded rubber bushes and not to preload the suspension with the bushes being clamped at other than actual driving ride height, to get the most cycles out of the bushes. Link to comment Share on other sites More sharing options...
KnifeySpoony Posted July 19, 2023 Share Posted July 19, 2023 If you are really trying to get it that precise, you will need to loosen then retorque all the bush bolts after any ride height adjustments in the future, or even as the car settles initially. I think trying to guess the weight and final ride height of your car at this point is wishful thinking... Link to comment Share on other sites More sharing options...
Yoram Posted July 19, 2023 Author Share Posted July 19, 2023 (edited) Slow progress with weights and ride heights... So... the path still is to first get the ride heights and cross weight adjusted in "loaded" condition. Then unload to "curb" and settle and torque the suspension joints. I raised all four coil-overs to maximum height (recommended starting point for a mostly road use setup with a wet sump Duratec). Lesson learned: Raise the coil-overs to max height before assembling into the car -- much easier... I then loaded the car to "loaded" condition, which for me adds 200 lb driver, 75 lb 1/2 passenger, and 10 lb in trunk over "curb", and rolled it off the frame and back onto the scales. I found that the LR wheel load exceeds the limit of my bathroom scale, and the RH one is barely under 400 lb. I guess I was a bit off in my estimate of the weight distribution... So I searched again on Amazon, this time with the keyword "extra capacity bathroom scale"... Well, they come in 560 lb capacity! I ordered two at $33 each. Another lesson learned... My approximate ride heights in loaded condition are 160 mm front and 175 mm rear, which seem not bad. Next will report corner weights and ride heights in loaded and curb after cross weight adjustment. Pics in loaded condition: Cheers! Edited July 19, 2023 by Yoram Link to comment Share on other sites More sharing options...
Yoram Posted July 19, 2023 Author Share Posted July 19, 2023 (edited) 48 minutes ago, MV8 said: The goal is to minimize the degree of twist with bonded rubber bushes and not to preload the suspension with the bushes being clamped at other than actual driving ride height, to get the most cycles out of the bushes. I know that. Rubber creeps and degrades also under static shear load. My plan is to torque the bushings in curb (parked) height as this is the position in which they will spend 98% of their life. Edited July 19, 2023 by Yoram Link to comment Share on other sites More sharing options...
Yoram Posted July 19, 2023 Author Share Posted July 19, 2023 29 minutes ago, KnifeySpoony said: If you are really trying to get it that precise, you will need to loosen then retorque all the bush bolts after any ride height adjustments in the future, or even as the car settles initially. I think trying to guess the weight and final ride height of your car at this point is wishful thinking... Yes, I will need to loosen and re-torque the bushing bolts after significant ride height adjustments and settling. You need to start somewhere. I am not guessing. I am simulating and measuring actual weights and ride heights. The weights are known and as close to reality as I want them to be. The ride heights may change in time. I will be monitoring them to decide if they warrant re-torquing. Iteration is a common process in development, as in life... Link to comment Share on other sites More sharing options...
Yoram Posted July 22, 2023 Author Share Posted July 22, 2023 (edited) Have Corner Weights Got my two extra capacity scales (only 550 lb, not 560... ) for the rear corners. Had to expand the frame a bit to make them fit. Got quite repeatable weight readings. Here are average values and the initial cross weight calculation in loaded condition: Current CW = 50.6%, which is not terrible. Will try to bring to 50% by lowering (=unloading) the LR coil-over, mostly to experience how sensitive it is (how many threads it would take). I do not plan on lowering the RF coil-over at all due to the already very low ground clearance under the Duratec sump. Will repeat this exercise and report after torquing the suspension -- to learn how sensitive the cross weight is to it and to see if it needs further tweaking. Cheers! Edited July 22, 2023 by Yoram 1 Link to comment Share on other sites More sharing options...
Yoram Posted August 3, 2023 Author Share Posted August 3, 2023 Torquing, Ride Height and Cross-Weight -- Complications and Conclusion (?) A bit of a delay catching up here, sorry. This one will be tedious for demonstrative and empathy soliciting purposes... Torquing: Following the status reported in the last post, I unloaded the "payload" part of the ballast and left only the ballast representing "curb" -- "ready to drive" with 1/2 tank of gas and no one in the car. I then rolled the car back and forth several time to settle the suspension and finally torqued all suspension bushing bolts. Torqued all connections per values in IKEA guide. This was pretty straightforward except for: a) Upper wishbone: Torque wrench access to both bolts and nuts is difficult. Both front and rear bushing joints required torquing the bolts, not the nuts; the front using a 2" torque extension for the torque wrench (and adjusting the torque setting), and the rear using a U-joint adapter and long extension, in both cases using an open wrench for counter-torque on the nuts. b) RH lower wishbone rear bushing: This is a Grade 10.9 M12-1.75 joint. For some unknown reason two "tall" (15mm total height, 12mm hex height) nyloc nuts supplied in the kit stripped while attempting to torque. All three other lower wishbone connections torqued fine with seemingly identical nuts. Don't ask me why there were extra nuts in the kit... I examined the bolt and it looked OK but wasn't sure of the correct pitch. To confirm the pitch and the bolt condition I bought a regular M12-1.75 nut at Ace hardware and tried torquing it to spec. It torqued fine! I am hoping to get a replacement nut from RMC. The cheapest way I found to get a tall M12-1.75 Grade 10.9 nyloc is to order a batch of 50 from Grainger... so for now I have the standard temporary nut torqued at the rear RH lower position. Ride Height and Cross Weight: Now came time to load back to "loaded" condition and finalize the ride heights and cross-weight. I did this and reached the target settings -- 50% cross weight, max ride height in front (as high as the adjustable coil-overs will go), and 15mm higher at the rear. ....here it comes... All looked peachy so the next step was simply to tighten the jam nuts under the platform nuts on the coil-overs. I unloaded the rest of the ballast, raised the car back on jack stands and removed the wheels, as simultaneous access to both coil-over nuts, especially at the rear, is impossible with the car on the ground. I used a C-spanner on the jam nut, and a conical punch on the main nut for counter-torque. Well... As I was turning the LR jam nut to raise it to meet the main nut (the spring platform) I realized, too late, that instead of the jam nut rising, the spring platform was lowering!! The threaded sleeve was turning with the jam nut and acting like a screw jack. The LR height and the cross weight settings were lost!! To pour salt on the wounds, now I could not unjam the jam nut from the bottom end of the threaded sleeve on the car... ....and clawing our way back... I jacked up the rear onto chassis stands, dismounted the coil-over from the car and unjammed it holding the flats at the bottom of the sleeve in a vise. Re-installed the coil-over confirming the jam nut and spring platform both rotate freely on the threaded sleeve. Dropped the car back on its wheels in preparation for a cross-weight redo... Assembled back the scales frame (which I had disassembled and put away...), placed and leveled the scales again, and filled up the containers (which I had emptied and put away...) with 300 lb of fresh water.... First loaded the car back to "curb" condition, rolled it back and forth, jacked up under the deDion tube, removed the LR wheel and and torqued the coil-over connections. Then dropped the car back on the wheels, loaded it to "loaded" condition, rolled it back and forth and onto the frame, and adjusted again the LR coil-over height to reach CW = 50%. While turning the LR spring platform I noted that threaded sleeve tends to rotate with it; fortunately only part of the time or slower... This was very time consuming and maybe the most frustrating episode of the build. But it's done. Here are the results: The ride height values seem quite good, and the rear-front height delta and the cross-weight values are right on target. Rebound Travel Concern: However, during this exercise I also measured the vertical gap between the bottom of the deDion tube and the top of the chassis rail in loaded condition and in full droop (rebound) when on jack stands. The difference, which is the net rebound travel in loaded condition, is just under 40mm on both left and right sides at the above ride height settings. I am concerned that this is too small and will result in frequent topping (shocks hitting rebound stops) on public roads. The only way to increase it is by lowering the ride height (in front as well to keep the 15mm delta) which of course will hurt ground clearance. Posed the question to Josh at RMC and am inviting any feedback here. Link to comment Share on other sites More sharing options...
Yoram Posted August 3, 2023 Author Share Posted August 3, 2023 (edited) Heater-Delete Blanking Plate and Grommet My kit came with the cockpit heater which I decided to delete. Theoretically there is a Caterham blanking plate to cover the heater opening in the "firewall" however it is currently unavailable with no time estimate. So I decided to fabricate my own from a 0.025" sheet of aluminum and bought 5' of a small U-channel rubber seal and M5-0.8x16 stainless steel screws. Had extra SS nyloc nuts and washers on hand from my wing stay attachments (subject of a future post). Used the heater as a pattern and cut the sheet with a small jig saw. After drilling I rubbed it with a fine Scoth Brite pad and WD40. Used the existing holes in the firewall and added one at top center for stiffness. Also used a short aluminum U profile to clamp the plate on the inside at bottom center without drilling another hole in the firewall. Used leftover length of rubber seal on the edges of the aluminum profile and along the top edge of the opening to prevent buzzing. One should also plug the heater cable hole on the driver's side of the firewall. I wanted a 1/2" (ID) blanking grommet which turned out to be more difficult and expensive to procure than one might think. Cheapest I could find was a 2-pack on Amazon for over $6.... It is visible below near right bottom corner: View under the dash: Aug 21 2023 edit: Added an external center rib (similar to the one I had installed behind the dash) to better clamp the plate to the "firewall" without "membraning" it. This is helpful if you want to avoid drilling a hole at the bottom center of the firewall (access is difficult). Instead, the two ribs clamp at the bottom on the firewall with the lower bolt passing through the heater opening. I used 3 flat washers between the inner rib and the plate to force the plate to sit flat. The ribs are out of a 1/2"x1/2" aluminum U (really I_I ) channel. A bit OCD I guess... Next post: Seats. Cheers! Edited August 21, 2023 by Yoram Link to comment Share on other sites More sharing options...
MV8 Posted August 3, 2023 Share Posted August 3, 2023 To protect the lower chassis rail from the axle tube, 6-8 inches of 3/4" heater hose split down one side would cushion as a droop stop. 1 Link to comment Share on other sites More sharing options...
Yoram Posted August 4, 2023 Author Share Posted August 4, 2023 On 8/3/2023 at 7:37 AM, MV8 said: To protect the lower chassis rail from the axle tube, 6-8 inches of 3/4" heater hose split down one side would cushion as a droop stop. Was thinking of something along the same lines but you nailed it! Link to comment Share on other sites More sharing options...
Yoram Posted August 16, 2023 Author Share Posted August 16, 2023 Suspension Torquing, Ride Height and Cross-Weight - Conclusion!! (now really) I ended my post of Aug 2nd with a concern about the proper trade-off between rear rebound travel vs ground clearance. In subsequent consultation with Josh Robbins of Rocky Mountain Caterham he recommended loaded ride heights of 148 front, 163 rear (with 14" wheels) -- 10mm lower than where I ended up on Aug 2nd... As always, I took his recommendation, but implementation required quite a bit of work... These were the main steps: 1. Untorque all suspension bushing joints and roll the car back and forth to settle the suspension 2. Lower the ride heights to the new targets and adjust the cross weight to 50% while periodically re-settling the suspension 3. Unload the ballast from loaded to Curb and again re-settle the suspension 4. Torque the suspension 5. Reload the ballast and re-settle the suspension 6. Final ride height and cross weight adjustment Here is the final (current) status. Here are some tips and lessons learned: Need to balance handling, ground clearance and ride quality. Increasing ride height reduces rebound travel. On an 360S S3 with 14" wheels, recommended ride heights are 148mm front, 163mm rear. This results in near 50mm rear rebound travel in loaded condition Pre-set coil-overs: For the above condition, set all 4 coil-overs so that 10-15mm thread protrudes above the spring platform/nut before assembly into car; saves a lot of work on the car Lubricate the coil-over platform thread (I used WD40) to prevent the threaded sleeve from turning with the platform/nut 80-90mm C-spanner with round peg works well. Need a second spanner or a conical punch to tighten the jam nut against the main nut To adjust rear coil overs and to torque radius link rear bolts under load need to jack up under the deDion A-frame bushing and remove wheels; nearly impossible to adjust with wheels and on the ground The thread pitch of the coil-over height adjustment is 2mm. This results in 1mm length change per 1/2 turn or 3 one-hole steps, which at rear equals the ride height change. In front, due to the coil-over ~45 deg tilt, 1mm ride height change requires about 1/3 turn or 2 one-hole steps Protect the lower spring coils and adjacent body surfaces and suspension parts with masking tape to prevent scuffing with the C-spanner or conical punch Measuring ride height is tricky and can be inaccurate and unrepeatable without special equipment, which I don't have. I may add in here later my clunky and time consuming (but repeatable) method... Bathroom scales (min. 500lb capacity rear) are very accurate and repeatable (compared same weight readings between scales and repeated measurements on same scales) -- less than 1 lb (<0.3%) variation. Need to make sure they are shimmed horizontal, not rocking, and tire patches are reasonably close to centers To torque the radius link front bushing with the seats installed, a stubby 8mm allen key (short leg <25mm) can provide counter-torque on the inside if the seat is pushed "all the way" forward Preload in the suspension bushings, when torqued at Curb, contributes ~2mm to the ride height in loaded condition (vs. untorqued). The car is now off my "scales frame" and back on jack stands. Next quick post will be about installing the seats. Then on to rear wings... Cheers! Link to comment Share on other sites More sharing options...
Yoram Posted August 16, 2023 Author Share Posted August 16, 2023 Seats Installed the standard (non-race) seats after torquing the suspension joints but before the ride height change and re-torquing. This required access to the front bolt of the radius link with the seats in. Please see previous post. Both seats are identical. The fore-aft adjustment works (within its limited range) and with my 5' 9" frame I actually moved the seat forward a notch to comfortably reach the pedals. Several tips: a) remove the bottom cushion for the installation (it comes off and goes back in easily) b) lay the lap belts (in a 4 or 6 point harness) pointing forward along the floor, place the seat on the floor, then pull the belts up on the outsides onto the seat to clear the rails and allow the rails full contact with floor c) use a spherical tip hex bit (H6), or a U-joint adapter on top of the hex bit, with long extension for the rear bolts and the fore-aft adjustment all the way forward; this is the most tedious part d) no problem installing the seats with the car on the ground (as I have) however it's more convenient to have it on jack stands e) keep the protective plastic covers on until completion of build, just make sure to cut out the bottom so it does not get caught between the rails and floor It was really fun to sit in behind the wheel for the first time, feel the pedals, wiggle the steering wheel and adjust the belts to fit!! Cheers! 3 Link to comment Share on other sites More sharing options...
Yoram Posted September 7, 2023 Author Share Posted September 7, 2023 (edited) Hello All, It's been a very long break for several reasons -- one was a detour for some unscheduled work on our Volvo XC70 (future Yellowjacket tow car...), which got deeper than desired. That part is done (I hope...). The other was due to my new decision to change (again) the build sequence. Instead of, as planned originally, proceeding next with the wings, I decided to first complete a DIY wheel alignment, while the wings are not in the way. I also decided to come up with my own alignment method using generic and inexpensive hardware. Generating the concept, procuring the bits, putting them together, tweaking them and evolving the process took quite a bit of time. I have completed this interesting and labor intensive step now, and the car is aligned to my satisfaction. The next several posts will document the method, equipment and results. I'll have them split primarily due to pic file size limits and to make it easier to post and read. Edited September 8, 2023 by Yoram 1 Link to comment Share on other sites More sharing options...
Yoram Posted September 7, 2023 Author Share Posted September 7, 2023 (edited) Wheel Alignment -- Concept and Prep I decided to focus on front wheel alignment only and not mess with the factory deDion axle alignment for now. The concept is to create reasonably precise, stiff, light and inexpensive frames which mount easily, repeatably and without damage to each front wheel rim and establish accurately its plane. Then use linear side to side measurements between the frames to calculate the toe angle, and a digital level to measure camber angle on each frame. I also added a moveable but rigid cross-car L profile (1.5" x 1.5" x 0.125" steel) on the floor which serves in turn to a) establish the floor reference angle between the wheel pads during camber measurements, and b) mark the cross-car distances between the frames for toe calculation. Finally I included a "slip plate" under each front wheel using a pair of vinyl tiles facing each other with grease between them. The wheel frame, "slip plate" and L profile: Next are a couple pics of the setup in camber measurement mode. First is the floor reference angle measurement and zeroing of the digital level on the L profile: Camber readout relative to the floor reference: Next are a couple of pics in toe measurement mode (the measurement is taken at both ends of the horizontal extrusions, pics showing the measurement in front of the wheel, similar one taken between the other ends behind it): Below is the main hardware procured (total cost <$150): Next we will cover the adjustment process and results. Cheers! Edited September 8, 2023 by Yoram 1 Link to comment Share on other sites More sharing options...
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