RMC #36 420R in PA

[Legs]

Nearly two years have passed and it's finally here! Very much looking forward to the build process. Josh at RMC is amazing!

 

Options added to the base 420R:

4-piston calipers

Battery cutoff

Trackday rollbar

Sidescreen armrests

Carbon seats

Sequential shift lights

Lowered floor

620 nosecone

620 carbon dash (I love those toggles!)

 

 

[slowdude]

This is gonna be a riot. Love the spec and the 620 dash on that fits perfect. Its chefs kiss perfect. 🤌🤌

[captain pabst]

Oh man that color! looks great. Hope to meetup at some point

 

[Timberline]

I really like the mint color! I've got mint stripes on mine

[JohnCh]

@Legs, how is your build progressing?

[Legs]

I've been slow to provide any updates, sorry. But thank you for prompting me to do so!! First couple weeks were busy (wrong kind) with work and covid knocking both of us out, but had a productive past two weekends! First one was all about preparation; bubble wrap and cardboard the body, pool noodles / oil hose cover the cross bars, spraying some dinitrol around the grot traps in the engine bay, confirming components, etc. 

 

This past weekend, we got the gearbox mated to the engine on Saturday along with engine install prep - removing the alternator, starter, serpentine belt, plenum, clearing the engine mount threads, taping wires down, and then protecting the cam headers. Everything takes longer than it will in my head hahaa.

 

Sunday was engine install day! Ultimately it went very smoothly - the hours of researching other blogs and planning paid off. From my friend arriving with his hoist to wrenches down was 4 hours including coffee and lunch breaks! And despite him thinking we would be installing and removing 3 times, we never had to raise the hoist more than a few mill. The only unexpected thing to work around was the gearbox mount holes simply would not align enough for the 4 mount to chassis bolts to seat, so that requires a tiny bit of filing. So all in all, I think it was very good.

 

Big thanks to Josh at RMC for alleviating any and all of my worries about, well everything. You can read about the extremely tight fit of the gearbox over and over, but man, experiencing it is another thing. We managed to only scrape 2 small portions of the reflective insulation, which was an easy, and anticipated, patch job for some aluminum tape I bought ahead of time for just the task.

 

Last night I got the starter and alternator back on, so next up is front suspension! I wish the kit was delivered a few months ago when I was on a planned sabbatical, as my new job started up and thus takes some priority, but I'm still making time to keep the wrenches turning!

[JohnCh]

Glad to hear you're making progress.  And yes, Josh is extremely helpful and knowledgeable.  Definitely one of the good guys.  

[captain pabst]

Looks good keep up the updates.

[Legs]

Front suspension, yea surely I can get the upper and lower wishbones on in a couple hours.

 

Starting with the lower, only 4 bolts, easy! Well 3.5 hours later, the lower wishbones are on. Torqued up, then untorqued, then torqued, aaand untorqued again. I couldn't get them to sit level when torqued as some blogs suggest as it is a not so easy task to tighten them up when on wheels, but I'll follow the manual on this one and figure it out when it comes time to drop it down. 

 

I had a good time getting the last washer in, as seems to be the norm. The holes were 1-2mm off on the LHS, so that took some figuring out, but the threads eventually pulled right on through.

 

I think I've to instill a personal rule: however long I think a task will take, multiply it by 3, and that's how long it will take. Time for a beer.

Edited October 14, 2024 by Legs

[Timberline]

Of the whole build so far, the front suspension is the step I am least satisfied with. I can't believe it's the first step in the build manual. The wishbone installation in particular was so difficult and took many sessions to complete. Every bolt was a challenge to install. So keep persevering. The future challenges are much more rewarding to work through.

 

Something I discovered after the fact that made my chassis even more challenging. For the top bolt of the dampener, you need to push the skin out of the way. My skin rides the chassis there (manufacturing flaw) and has no travel inside. I had to push the skin outwards. Literal blood, sweat, and tears later, I got that bolt in. Now that I know this is a flaw, I should have trimmed the skin or frame a little to eliminate the riding clash and popped the skin inwards as designed.

[Legs]

Thank you for the input, @Timberline! I've only just managed to get the upper wishbones on, but I will have your words in my head when the time comes for the dampers. My old man came down from New England for a visit and we were able to do it together, which was a special moment. He had a large part of this whole project in telling me at a young age that sometime, we'd buy an old car and fix it up. Something I've learned his father told him too and never happened haha. Our time has come and gone for that, but my desire to do so never dwindled. When I told my wife that a few years ago, she persisted in making it happen in one form or another, and he we are! It was a good weekend despite having to break out the file to get the bolts to fit through the holes, the hammer to pry the headlight clip open more to align the bolt holes, and scavenging to locate the appropriate unlabeled upper wishbone bolt sleeves. It's about par for the course :-)

[Legs]

It's starting to warm up again which means we're FINALLY able to get back at it!! It's been a productive few days, got our front assemblies completed without a hitch. One of the brake lines needed a little bending to mate up, but nothing serious. So on to horn and headlights! I only had to look for the horn spacer for 35 minutes, only to realize there's no bolt to be found. No biggie! Moved on to the headlights but also stalled out looking for the hardware pack. I triple checked everywhere and no dice. The parts list says 12 z-packs, of which where are, so I guess there's supposed to be 13 including the height pack C 😆 Alright, let's keep moving!

 

Tidied up the engine bay electrical before starting on the plumbing! I got everything laid out, but then decided to hold back because I think it will only make getting the headlight wiring in and torquing the wishbones down a lot more difficult with the hoses in place.. so next up was the handbrake!

 

After reading through some of the immensely through and helpful build blogs, I came to the conclusion that it's probably better to wait until the prop shaft and diff are in. The diff looks to be difficult, so no need to make it any harder restricting space and views. So we put the handbrake cable in and moved onto the prop shaft.

 

Prop shaft was very simple! It took much longer to track down some moly spline paste than it did to install. Is it necessary? Probably not as it's not mentioned in the manual, but I like to be safe and it will only be beneficial. Thanks again helpful build blogs!

 

On the same note, when I topped up the prop shaft grease joints, I was only ever getting spew from one of the junctions, same on both ends. So was I simply not supplying enough? In other scenarios, the train of thought was keep going until you get fresh grease from everywhere, but it didn't seem to be the case here? 

 

Caterham seems to have addressed a complication with prop shaft install in the joints being slightly wider than the frame uprights, but my frame had some fancy curves to it, just the right amount for the shaft to smoothly drop in. Kudos!

 

Now on to the differential. It doesn't look like a one man job, it's got some heft! My wife is a bit under the weather, so it wasn't going to happen this weekend. I took the opportunity to follow some other's suggestions to paint the machined connection with some engine enamel. The install will have to wait. Any and all tips and pointers are welcome! We have two jacks, but no engine crane. Seems that people have done both, but the crane does seem nice to keep things steady. I can probably convince our friend with a crane who helped us with the engine install to come help in exchange for a beer or two. 

 

Happy to be back in the garage and seeing things take some shape! ✌️

[JohnCh]

There are a few ways to do the diff, and although I'm sure it's easier with help, I did mine solo with a floor jack and a simple cradle made from scrap wood to keep it steady.  

 

 

 

-John

[Timberline]

I had a little bit of drama with the diff, but it was totally on me. The two front bolts go into threaded inserts and I cross threaded one. Then I just kept after it and destroyed the bolt. I was so excited when I caught all the washers successfully. With how stupid I was being, it could have been a lot worse.

 

 Knowing that, no matter how wonky the fit is (and mine was really off) get the front bolts in straight first. The aft bolt takes a nut so you can beat the snot out of it and put a big taper on the threads to help with alignment and washer catching.

 

Another option is to take the frame off of the diff and install that to the chassis first. It really made my installation easier. You should take the frame off anyways if you are wanting to paint all the bare surfaces.

 

I did the floor jack method to support the diff. With the weight taken by the jack, it’s easy to position with someone else on the jack.

[Timberline]

Just remembered though. If you are taking the frame off the diff, consider the washer shimming.

 

I already had my shimming measured and figured out.

 

I still think it’s a good idea to lift the assembly, figure out the shims, lower it, disassemble, then install the frame first. Because you are only messing with internal shims holding the light frame and not the heavy diff.

[Legs]

Well that should make things easier, thanks for the solution @JohnCh, any excuse to use more tools is always a good one 😊

 

@Timberline I like the sound of taking the frame off when it comes time to mounting.. do you happen to know the torque numbers on those bolts? Being that we'll be raising it up intact to at a minimum determine the shims, we'll see what it's looking like to get the bolts in. Great back pocket play to remove the frame if needed.

[Timberline]

The frame seems like a way for Caterham to fit different diffs and not change the chassis. It’s the same three big bolts in the frame as in the chassis, so I just copied the published torque values for both steps.

[CBuff]

https://caterham420detailedbuildblog.co.uk/2020/01/04/differential/
 

[S1Steve]

C Buff,Thanks for sharing Chris Collin’s build manual. Off I go down the rabbit hole, it’s so well written and detailed I’ll read the whole thing. Cheers Steve

Edited yesterday at 01:16 AM by S1Steve

[Legs]

It's one of the best! Something I've found immensely helpful is https://www.tiggercaterham.co.uk/tiggers420rbuildmanual who actually took the time to go through several of the detailed build blogs and pull our the helpful tidbits and not only list them out at the start of each section, but also provide the link to turn! It's a gold mine haha