CtrMint

Setup Question, I’ve now had chance to track both my 420R and 620R, the 620R being my usual track car. What I’ve noticed is that my 620R really wants to open the steering in any medium to high speed corners, and it requires a notable amount of steering force to stop it. Which can become draining through the course of a day. In comparison the 420R doesn’t, the effort required to hold mid corner just isn’t needed. Both are running ZZR tyres. I don’t believe my corner speeds are that different as I know its one of the areas I need to improve on. I’m lacking complete confidence in terms of corner entry speed and faith in how much speed I can carry, and so I’m sure they’re at similar speeds, I’m also reasonably cautious picking up the throttle again off apex. The 620R turns in really well, as does the 420R, though I’m probably lacking sufficient experience and pace to really pick out any variance. I’m assuming the difference will be down to the spacing on the lower wish bone? I’d like the 620R to operate similarly to the 420R whilst not compromising straight line stability. Unfortunately the 420R is at home, and the 620R is currently sat in the trailer, sorry I can’t state what the spacing is like on either Seven. But given the rain is pouring down I figured I’d post. Although I might be barking up the wrong tree 🙂 Any recommendations?

Hi, Does anyone have any recommendations for a Rad+Oil cooler other than CC and Radtec? Thanks

awesome and thank you.

I'm going through the process of fitting a Radtec radiator and oil cooler to my 620R and decided to source new bobbins in case the originals had stiffened with heat exposure. I wasn't looking to deviate from the intended specific, just save a few pennies from a specialist hardware supplier rather than CC.

Started to figure this out, though maybe a Seven suspension expert can offer a view as to what’s happening. My 620R was corner weighted, and so there is a difference in the spring platforms changing the droop in the strut when the chassis is support on axle stands. If I lift the side which is lower by say placing a trolley jack under the brake disc, it takes up the slack and moves the Dedion laterally as well. I guess there is some form on moment at play within the axle. I need to place the spacers as they came off, to fully test, but the above seems to the explanation as to why I’ve been struggling to centre the tube.

I managed to drive the 620R for a few meters around the cul-de-sac today, no more than 15 to 20mph. It was a big improvement in noise, I didn't spot any clunks and no apparent noise from the final drive, which would have been apparent on the previous diff even at slow speeds. So reassuring it wasn't my Sadev. I have no idea why the final drive fitted to the Tracsport was so bad. The 620R is back on axles stands as I'm trying to get the Dedion properly aligned.

Hey All, I am encountering difficulties with centring the Dedion on my 620R after completing my diff change. In the process of swapping the diff, I removed the A-frame and roll bar, followed by the ears, hubs, and shafts as a single unit, I intentionally left the Watts linkage and Radius arm untouched. Once the diff install was complete I reverse the process to reinstall. Upon reinstalling all components and conducting a thorough sanity check on the Dedion, I noticed a bias towards one side. I made sure to reinstall the A-Frame spacers in their original positions, and I've even experimented with various spacer combinations, but the lateral balance remains largely unaffected. I am contemplating whether the combination of the Radius arm, Watts linkage, and suspension struts might be restricting the Dedion's lateral movement. Should I be doing the centring process without those attached? If they are to blame, surely once reattached the offset will return... 🤔.. Any recommendations would be very much appreciated. Thank you

Hi, Does anyone happen to know the IRHD of the factory bobbins from Caterham? Thanks

Thank you Benton

Could I possibly inquire as to how much oil the Ford diff housing needs, my Caterham manuals covers the BMW Titan setup. Not sure if a my Drexler vs, Tracsport or Titan makes a difference. Also this might be a silly question, but can I fill through the drive shaft openings. I noticed when I removed the shafts with the car on stands I didn't loose any oil, though tipping the diff when removing resulted in egress. Thus can I fill that way, it would be, I think easier and faster. Thanks

Thanks JV, not too specific then.

Thank you for the warning. As I've now 2 complete ford based diffs, if I screw up fitting one I could steal from the other 😀 Steve, don't forget this is the ford diff, so no carrier, and slightly bigger than the BMW housing on the 420R. Last night I spent a tonne of time Googling grease for the drive shafts on the diff side. I'm pretty sure that grease should be used during fitment, it was already on the splines and bearing surface during removal, but I can't find specs to get get things absolutely correct. Can anyone recommend the type of grease for the splines, the bearing face (not sure if thats the correct term) and also the outer seal on the diff if required. Thanks

It's out 🙌 I'm not sure taking it out with the dedion in place was such a clever idea. There was a little too much contact with the dedion when trying to lift the nose of the diff and achieve the correct angle over the chassis structure at the back of the transmission tunnel. Maybe I should have removed the some of the hardware from the watts linkage etc, to provide a bit of play in the dedion. Next up is that pesky handbrake cable, hopefully with the diff removed I can get some mole grips on that adjuster. Any recommendations for getting the diff back in? Angles etc, should I lift the nose at 45 degrees etc. Also there's a breather pipe on the Ford diff, which is new to me, any gotchas etc with that? Thanks

I actually got the spec from my 420 build manual, the "Ikea" manual. The manual and bolts align, so I guess this has become the new standard.

Thanks Jonathan, I found this old thread,