sf4018

Suggestions above make sense but I'm curious why the bolt/nut is getting turned instead of the bushing to begin with...is there anything that could be causing the bushings to bind up? Maybe excessive lateral force, not seated against washers properly, etc...

I found this on my computer, I think it's from the Caterham maintenance manual which you may already have, but here it is anyways... Caterham Service Schedule - Duratec (1).xlsx

That seems like the lowest hanging fruit, hopefully that gets you enough of the way there.

Will do!

It was an inertia roller, can’t remember the brand, but it wasn’t fancy.

I got 204HP after 15% add on for drivetrain loss. It was tuned quite rich, focus was response and reliability rather than outright HP, so there’s no doubt more in there. 141HP does seem off.

Thanks Croc! Thanks Carl! Good luck with your project!

A real test for the new A Frame... I'd always heard about Turn 1 and 17 but until you drive over it it's hard to comprehend how bumpy (but fantastic) this track is!

Just to defend the honor of the A frame a little, the bent A frame I got last month came after a track weekend at COTA on slicks. I looked back at the video and I was getting 2g lateral force at really bumpy parts of the track, particularly some of the bad curbs. I raced a well sorted E46 a few weeks later there, the engine belt came off at the Esses the vibration is so harsh.

Just for closure, it turned out to be a broken 12V (GO) wire in the engine loom somewhere near or at the oil pressure connector. The broken wire worked when the engine was not running (which made troubleshooting confusing) but with the engine running the vibration caused it to open and close, creating noise for the oil pressure sensor. I suspect my crappy dressing up of wiring in that area with the long pressure sensor cable combined with 130mph winds blowing it around was probably the cause. That area seems pretty exposed. I've ordered a new engine loom, hopefully the engine doesn't have to come out to swap it out.

I used the spare oil pressure sensor connector cable…it has 3 wires, 12V, 0V and signal.

Here’s the oil pressure feedback when powered by a portable battery… …it’s stable and the correct voltage level. Here’s the oil pressure feedback connected to the normal supply from the car… …it’s all over the place! The ground seems solid at the connector - it stayed close to 0v to chassis and 0 ohms. The 12V though seemed a little erratic between 12V and 14V. How solid is the 12V supposed to be?

The drawing I made is based off of that, it’s factory wiring still. I find it hard to read without drawing it up.

The drawing above shows 4 wires (12V supply, GND, Signal, 5V Ref). The sensor itself only has 3 wires - 12V, GND, Signal). The weird circular connector that connects the engine harness to the sensor pigtail has 4 wires on top, 3 wires on the bottom. What the heck is the 5V reference wire for? It seems the signal feedback is adding 5V, so instead of 2V (2.8 Bar) on idle it's showing 7V (off the scale)...

I’m pretty sure it’s an electrical wiring gremlin somewhere at this point. Here’s the electrical wiring for the oil pressure sensor… Not sure what the point of the 5V reference is, but the 5V, 12V and GND are testing ok. What I didn’t know until I researched the schematics is the feedback also goes to the ECU as well as the gauge (strangely via the tach), and also the unused connectors on the engine harness on the left side near the oil filter can be used to connect the oil pressure signal and a GND to something. The signal WN52 is reading 7-8V, which is not possible for a device that can only put out 5V, so there has to be a bad ground or something like that somewhere. Grrr.

It's the original Caterham oil pressure gauge, dunno what type.

The last track day the oil pressure suddenly maxed out while on track. So I got a manual oil gauge, plugged it in the engine and ran it, it was perfect. Engine is fine. I then got a new oil pressure sensor and harness and swapped them out. Ran the engine, it maxed out again. Not a sensor issue. I unplugged the oil pressure harness while running and the gauge froze in the position it was in (almost max). I’m stumped what the problem could be. Anyone have any inspiration?

I have the replacement A Frame, the old one was bent fairly equally on both sides - see pic, not sure of the physics of how that happened but definitely needed replacing.

This is one reason I swapped out the ECU.

If the ECU is internally showing the correct RPM on easymap it sure sounds like the pulses per RPM setting for the tach output in the ECU is off. I had the same issue a few months ago when I swapped out the Caterham ECU for SBD one - the default setting for the tach output was 1 pulse per RPM and the tach was showing 25% of the RPM. It was fixed by changing the setting to 4 pulses per RPM. Not sure what can be done with what you have.

No, but I have a spare stock Caterham 420R ECU (2018) if you want to borrow it to see if the ECU is the issue or not.

Sorry it was a poorly worded - it’s the front of the rear A-frame. Based on that pic in the link I may just get a new one. Thanks for the info.

I noticed a creaking metallic noise the last time out, I’ve isolated to the front A-frame it feels bound up. Is the joint broken or does it just need some TLC like grease?

The explanation for the cross-member damage due to a tow strap appears sketchy to me. I would hazard a guess those notches were made by a more robust collision. It may be worthwhile getting the frame checked out to see if it's square or deformed in some way.

Well it looks like there will be 3 420Rs on track this weekend in the same group too, super excited about that. Not sure if the other 2 drivers are on here?