RMC #36 420R in PA

[JohnCh]

1 hour ago, Legs said:

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

 

I forgot about this one.  I just added it to the Build Blog links thread:  

 

[Legs]

Diff Day 1: diff wins 

 

Bottoms weren't too bad. I put one in to pull the diff to one side to them determine the total washers/shims needed in total. Split those in half and have an equal amount for each side, back the bolt out, then add washers and bolts.

 

Top bolt, as expected, is going to need some finagling. Top left has a small gap, I can get one thick and one medium washer in while jostling the diff to make space, so that's tight. Top right has enough space for two thick and probably can squeeze a smaller one in. The bigger issue is simple getting the diff in line with the holes, it seems like it needs to go another 1/8" further into the car, but the front bolts naturally won't allow that. Possibly swinging the rear towards the right wheel well is what's needed, given the left side is tighter than the right, but again, the front bolts will keep it from moving off it's current line AFAIK. Not sure!

[Timberline]

Sounds about right. The shapes are not the same as fabricated.

 

 Putting a big taper on the bolt and/or using pin punches are the tools for the job. That and a big mallet

[JohnCh]

11 minutes ago, Legs said:

Bottoms weren't too bad. I put one in to pull the diff to one side to them determine the total washers/shims needed in total. Split those in half and have an equal amount for each side, back the bolt out, then add washers and bolts.

 

In case you split the washers evenly because that is implied in the build manual, that is not necessarily correct.  When Caterham introduced the Ikea-style build manual in an attempt to make assembly appear easy, they left out information from the earlier, and more thorough written manual.  In the case of the washers, the Ikea diagram shows the same number washers on either side, implying they should always be equally split.  However, from page 129:

 

"Measure from either side of the differential carrier to the outboard side of the chassis (outboard of rear ARB mount – 1” BOX) to centralise. During this process there will be a need to pull the bottom bolts out and use shim washers (item 21 in pack 30Z1067A) inserted in between the metalastic bush and carrier as necessary. You may now use the ½ x 11” top bolt (schnorr washer under the head). It is optional to grind a chamfer on the end of the bolt (threaded part 45 degrees x ½”) as this makes it easier to slide and locate the top bolt. Ensure there is plenty of copper slip used on the bolt. You will also need to space the upper bolt between the carrier and the metalastic with shim washers. Use a ½” nyloc nut and schnorr washer to fasten the bolt."

 

You might have it centralized, but it would be good to check.  The written manual is in the Library:

 

 

 

[Legs]

Thank you @JohnCh, from the eyeball it does seem like it's not centered on the bottom bolts, but because it's implied and I split the washers I thought, it must just be shadows or bigger welding on one side skewing the appearance. But this makes me think it really might not be centered. I was trying to measure between the case and the inside, not easy. Measuring to the outside of the frame should be much better and accurate 👌

[Legs]

Diff Day Two

Diff's up 2-0. I reshimmed the bottom bolts to get the diff frame to rear ARB frame tube as close to even on both sides as possible. Can't say it's down to the mil, but it is definitely closer than it was. Getting the second set of washers in took way longer this time around 🥵 I also removed the makeshift cradle so the jack can push on the diff from further back to better utilize the front bolt pivot point. I was hopeful the top holes would be better aligned now, but it seems to not have made any bit of difference. The holes are pretty close to aligned vertically, but the diff's are still 1/8" too far to the rear. I don't understand how any bit of pushing and shoving can make up that amount, on both sides. A bit discouraged for the moment, but tomorrow is another day.

Edited March 27 by Legs

[KnifeySpoony]

You have to deflect the bush enough to get the bolts in. Massive PITA and takes a lot of muscle/prying/hammering/swearing.

[Legs]

Diff Day 3: It's done.

 

I honestly still didn't think it was going to happen today - spent another 2 hours moving, jiggling, hammering, with no change. Another hour passed with my wife maneuvering the crobar been the diff and the jack. At some point, she got it just right and a few knocks with the 5lb hammer, the bolt started to go in and it just kept going. Lathered it up with more copper grease and sent it home. We promptly went out for a deserved beer 😆 I'm glad that's done with. Thanks for the words of encouragement!

 

PS. If anyone sees this who hasn't installed their diff, remove the plywood boot floor and it makes getting access to the top washers very easy. You can get a full view of them and easily use a flat head to push on them 👍

Edited March 29 by Legs
Adding a PS

[Legs]

April was a wash because we were away, but I've been busy the past couple of weeks. Drivetrain is nearly complete, but brake bleeding has been far more challenging than expected and I'm in need of some help. 

 

I've bled them the traditional way 6 times now, but there is still about 5cm of free pedal travel before it stops from resistance. It's not squishy and doesn't pump up, it's consistent nothing until very hard, but seems like a lot of travel from what I've read and was expecting. I haven't touched the handbrake yet - the cable is backed off all the way and attached to the calipers. 

 

Research tells me it's possibly air in the rears still? The bleed nipples not being vertical tends to lead to some residual air? I dunno. I've been convinced to let it be for now until taking it out for a drive and seeing how things go, but that won't be for some time still. 

 

So I am seeking any and all advice on that matter, but the more pressing one is the front brake connection is leaking a tiny amount. I've triple checked that the correct, grey adapter is used, as is the larger copper washer. I've tried tightening up the adapter a little more but I can't do it any more without rounding of the corners due to it being half height. The only way to get it any tighter would be bleed the system so I could put a socket on it, but have been told that likely won't make any bit of difference if it's already tight enough that a spanner will round it, so I'm at a loss of how to proceed. The only bit of info on the matter is from https://caterham420detailedbuildblog.co.uk/2019/12/16/front-caliper-brake-hose/ where he says installing the washers whilst cold was problematic and he had to purchase new ones and warmed them up before installing. It was late May when I installed them, I don't think it was cold, but I don't know what else 😞

[KnifeySpoony]

Based on your description of the pedal, it sounds like you're not building any pressure in the system at all, and what you are feeling is the pedal/MC bottom out. I have found the brakes very easy to bleed on this car, so I wonder what is happening for you. If indeed you aren't building pressure, you would need to either have an opening in the system or a ton of air hiding somewhere. I'm not an expert on master cylinders, but some people tout the need to bench bleed masters. I don't know if something with the MC could cause your symptom or not.

 

 

[Legs]

2 minutes ago, KnifeySpoony said:

Based on your description of the pedal, it sounds like you're not building any pressure in the system at all, and what you are feeling is the pedal/MC bottom out. I have found the brakes very easy to bleed on this car, so I wonder what is happening for you. If indeed you aren't building pressure, you would need to either have an opening in the system or a ton of air hiding somewhere. I'm not an expert on master cylinders, but some people tout the need to bench bleed masters. I don't know if something with the MC could cause your symptom or not.

 

 

Thanks @KnifeySpoony, would I be bottoming out the MC even though I can see the piston on the rears moving?

[MV8]

I think you have the wrong fittings if those are wilwood calipers. I would expect pipe thread/no sealing washers. Also, those fittings are not made for sealing washers.

 

The pedal ratio is likely 6 or 7 to 1 so you are not bottoming out the master cylinder with a 1/4 inch of piston travel.

Edited June 11 by MV8

[captain pabst]

So some research on the front adapters (with the 4 pot calipers in the front) say they need to be annealed if leaking (this is obviously really messy now that there is fluid in the system) another thing to try is to tighten loosen and tighten a few times making it seat better. Yes this actually worked for me, but i wished i had annealed mine before putting them in place

Have you bled both valves on the front brakes? there is an inside and an outside for each caliper. my drivers front had a lot of air on the inside bleeder. I used a power bleeder and the old school way second and felt the brakes were done after pumping and cracking bleeders.

Good luck! hope you finish up soon.
 

[Legs]

Thanks all! Yes, they are the 4 pot calipers, fairly certain the adapters and washers are the correct ones, and I have bled both inside and outside on each round. Though my order was slightly different than Josh at RMC, so I'll follow his order once I get the leaking sorted.I also ordered an adapter for the power bleeder we have so I can try using that on the 7 as well once the leaking stops. I will give loosening and tightening a go, that's something I haven't tried and is worth a shot!

[captain pabst]

for the rears you can always put tires on the fronts (easier when the car is done) and jack the rear up until the calipers are more close to level / bleeder being the high poitn ( i did this as my car was "done" but was looking for a bit better bleed on the brakes)

[KnifeySpoony]

2 hours ago, Legs said:

Thanks @KnifeySpoony, would I be bottoming out the MC even though I can see the piston on the rears moving?

Not sure, but if it's just still some air in the line, you should be able to "pump up" the system and get harder/higher pedal. If it's really no resistance, then hitting a brick wall, it sounds like bottoming out. Maybe 5cm is not enough though. I'm honestly not sure what my total travel is. Thinking about it, maybe it's more like 10cm. 

[Legs]

1 hour ago, KnifeySpoony said:

Not sure, but if it's just still some air in the line, you should be able to "pump up" the system and get harder/higher pedal. If it's really no resistance, then hitting a brick wall, it sounds like bottoming out. Maybe 5cm is not enough though. I'm honestly not sure what my total travel is. Thinking about it, maybe it's more like 10cm. 

Yea pumping definitely does nothing! 🤷‍♂️ He's a clip showing the travel 

[MV8]

I expect that Cat made special, minimum id washers that must be threaded on to the fitting to seal adequately. The washers would appear not to fit because they don't slip over the thread major diameter.

 

Annealing helps if you are up to the challenge of using a hand torch. I bet there are videos you could pull up on annealing copper washers. I hang the washer on a steel wire, bathe the washer in heat evenly until it glows (about a second), IMMEDIATELY  take the torch away to prevent melting the washer and drop the washer in water to quench/rapid cool.

 

You should expect some pedal travel.

 

You might contact a local tech school, aerospace engineer or commercial/industrial hydraulic hose and repair facility to show your caliper and hardware for an opinion (they cannot work on it anyway or provide any fittings if they know it will be going on a car).

 

 

 

 

Edited June 12 by MV8

[KnifeySpoony]

Video not working for me

[Legs]

23 minutes ago, KnifeySpoony said:

Video not working for me

Works from my phone and desktop on Chrome, what browser are you using? It takes a little to load up. Were you getting an error or just seemed to not load, if so give it a minute