ChrisC

Why is your diff on its way out?

Any plate diff, but the "normal" and "rebuild" torque figures will be different.

I know you have the tools to follow this procedure. https://caterham420detailedbuildblog.co.uk/2020/10/18/differential-preload-check/ What preload have you got?

Neutral, the propshaft will turn once the preload is overcome.

My 360R had a flat floor setup during Post Build Check, at the time Caterham gave three ride height options, Road, Aggressive road or Race. I choose Road, mainly to ensure I could get my car on the drive. I never hit the sump in 2 years of driving on Essex roads, it handled well, mainly due to the flat floor setup, but ultimate lap time would have been compromised. Not that matters over being able to get it on the drive. At the moment my 420R is set high, Caterham now only perform a flat floor setup after 1000 miles. Oh and on the diff question, loads of noise about this at the moment, but this is a problem I have been aware of since 2018, and yet I still ordered a car with the R spec/Titan LSD unit. I was always going to monitor it, and decided my course of action when need. After all a new kit will have a warranty meaning its not a financial problem for the first two years at least. I bet Caterham haven't got a demo 420 with that tyre combination.

Hi Richard I am Essex based, and more then willing to help, as most of the Essex bunch are. Having owned a Sigma 150, 360 and 420, I feel qualified to answer your question. My Sigma 150 (similar to the 310 but with throttle bodies) was the car I felt most comfortable with. I felt I extracted the most out of on track. On the road you could stretch it's legs a little just for the enjoyment without things getting to silly. My 360 lacked something, character I think, I still haven't gelled with duratecs on track, but I just need more track time to do this. I had a high ride height set to resolve the sump issue. Performance was ok, but it felt faster, but comparing video lap times there was little in it (but my 360 had a windscreen). Road use was limited more, possible but in fewer places. The 420 needs respect, it feels angry, and planting the throttle needs to be a considered action, so you won't find may places on the road to stretch the legs. I have only had one wet Trackday in my 420, but I still felt that balance thing I have to work on. For me it would be between the 310 and the 420. The 310 is easier to build. The 420 is a little OTT. If you want bonkers mental, get the 420. If you want balanced all rounder go for the 310.

It was my car Caterham supplied the rear exit for (IVA July 2020). They don't normally do it, because in 95% of cases its not needed, but since the IVA was early post lockdown a true belt and braces approach was taken. Ironically the parts supplied didn't fit my car, and there wasn't time available to resolve that, so the car was tested (and passed) with the side exit.

I believe the internals are the same (based on the Titan website), and maybe its because the week carbon plates only started post 2014, based on post #34, so long after the swap from Ford to BMW diff by CC. What I haven't ever seen is complained about the Ford Titan LSD unit.

Remember that's based on carbon plates, fitted post 2014/2015(is) to early 2018. Your 420R doesn't have carbon plates, that's why your diff tends to bang, according to RRT, but can be improved that with their special blend oil. Your 620R, I believe, doesn't have a BMW Titan LSD. I think 620Rs are fitted with Ford based Titan LSDs, but I don't know what plates were fitted. If you check and monitor your diff's health, and rebuild when the preload is no longer within specification, you will minimise the rebuild cost.

A mates factory 420R from march 2017 had carbon plates, and when I checked it a few weeks ago, it had so little preload there was no need for a torque wrench.

The only failures I have heard of are basically LSD that no longer act as LSDs. Testing the preload at service time is what's recommended by RRT, apparently they start out with 40ft/lb preload (or maybe a bit more when new), 20ft/lb its rebuild time. 15ft/lb impending doom. You test one wheel off, and the other touching the ground. The preload is the torque required to turn the hub. I use a digital torque wrench set to record peek torque.

I don't think the reliability is anything to do with being BMW or Ford, so swapping to a Ford casting with a Titan LSD with carbon plates might solve nothing. According to Titan, the plates are the same between the two units.

Just for reference, all Titan LSD CC supplied since 2018 (ish) have been fitted with the sintered internals. Since you have the car on order I assume you have test driven a 420R and are aware of the noise the sintered internal make when not pushed. If you haven't then I would advise booking a test drive to satisfy your worries. Ensure the car you drive has a sintered LSD, and resist the temptation to put your foot down, consider driving as if you were running it in. As for the other important question, sintered Titan internals have only been fitted since 2018, meaning the life expectancy is unknown. To a certain extent thats also true for the SPC diff because its also new. A comment was made earlier in this thread that the Titan was considered a wonder replacement a few years back. BUT there is a simple test procedure outlined on this site to gauge the life of your diff. You will be able to monitor your diff from new and thus get the maximum out of what CC supplied. Basically panic not. I am in the same boat, my 420R has only been on the road since August, I will monitor my sintered Titan diff, and decided to replace or rebuild when the time comes. In the mean time I will enjoy the car for what it is.

I use a pin punch (of the right diameter) from a set like this https://www.toolstation.com/pin-punch-set/p44554

Hi Bob 1, There are three seat shapes available to order, Tillet (Race), Tillet (620 Carbon) and S-Type leather. Tillet (Race), as fitted to academy cars, are available in either kevlar or GRP, these tend to be tight fitting but I have heard it said kevlar are slightly more comfortable. S-Type leather and Tillet (620 Carbon) are more suitable for larger drivers. Comfort is subjective, I for example prefer Tillet (Race) over S-Type leather for comfort. 2, The springs fitted to the front dampers is all that's different (Sport to Track Suspension). It's actually cheaper to buy the springs from the parts site and swap them if your building a kit, especially if you sell the standard items. It's much like the carbon indicator mounts, which are cheaper from the parts store than to order with the kit. I am sure there are plenty of people who will tell you how much better / worse they are than the standard spec. I personally would spend the money on getting the car flat floored and the geometry spot on first. Sport Suspension is standard 420R spec, and that has adjustable platforms. Race Suspension used the 620R spec dampers and springs. (FYI Road spec (S models) is the same as Sport, but without the adjustable platforms) 3, Noise is measured static and drive-by, the IVA static noise test is actually stricter than Bedford Autodrome, which is generally considered the most strict nose level track in the country. That said drive-by can be a problem dependent on the mic location and track. For example Brands can be tricky, but I have seen plenty of 420R videos on Bedford. Finally it also depends how hard you can push it, so the same car with a different driver can have problems. I went with the side exit, if I start getting problems I will upgrade to a Raceco side exit, mainly because I don't like the look of the rear exit. 4, I think the main hidden difference between ordering with or without weather gear is cars not fitted with factory windscreens aren't fitted with wipers. So in general without weather gear is a brave initial option. The hood is useful if you ever leave your car outside overnight, so it's not something I wouldn't be without. Half hood for driving obviously ;-) Hope this helps PS - think about the track day roll bar ;-)

I remember building the bulk buy lenses, you had to stick them together with clear epoxy, so I imagine trying to transplant the reflector might result in a broken lens. https://www.bowerspartsonline.co.uk/lighting/rear-lighting/replacement-light-lenses/caterham-westfield-kit-car-clear-rear-combination-tail-light-lens £9, not bad to be honest

Also I think they have the narrow shoulder straps for the HANS device.

They are the race belts, so any 2020 academy cars will have them (well at least one). As for the fitting, the new manual covers that. Does the carbon seats have a hole for the 6 point harness?

You can't adjust the mixture, most of the time it's controlled by the lambda sensor. If you have a mixture problem then you need some computer diagnosis with EasyMap. But I bet the lambda sensor is duff.

There is a website you can use to check the hologram on the box, to check for fakes. https://protect.bosch.com/

So the obvious question, do you think part could have been a fake? Just based on the price it was very cheap?

The spacers are used to position the seat away from the bow and the tunnel. In your car case they have been added to tip the seat towards the tunnel, because it probably touches the bow without them. They are also used to tip the seat back a bit. Often added to stop your head from being pushed forward when wearing a helmet doesn't.

They are just normal Tillet spacers. I wonder if they have been stuck them to the floor to make the install easier. If you put the spacers under the runners then it would be very tricky to stop them moving as the seat is installed. Interestingly the factory told me recently that they prefer to fit the spacers between the runner and the seat, so the load on the floor is more uniformly spread. Obviously not all the builders are following that approach.

I use a length of heater hose duct taped to the vacuum cleaner hose to get all the stones / dirt I can see behind and under the seat. What I can't see I don't worry about until the seat is removed.

The nut has been replaced with a rivnut, and the lamp is secured with this screws https://caterhamparts.co.uk/other/3351-countersunk-screw-fog-reverse-light-fixing-pack-of-5.html The lamp units are modified versions of the Land Rover parts. In the Land Rover they have a nut holding them from the back, and a bolt molded into the black plastic casing. Caterham removes this molded nut, and counter sinks the hole to use the screws above. It saves the need to remove / move the tank for removal and refitting of the fog light. Once removed you will be left with one hole for the wiring and a rivnut either side.