CtrMint

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,

I went back to it this evening for an hour or so. Used an old Sealey 1/2" torque wrench covered in rags, having put my entire body behind them I've 3 out. There's traces of some form of thread locking agent on the threads, so I'm going to replace the bolts. I didn't take the 4th out as I didn't have time for dealing with the prop etc. But at least that's progress. James wrt to the impact gun, I've bought some super long hex sockets, and also impact UJs, but still waiting for those to arrive, island life. 😄 WRT to replace the bolt, I can see they're caphead M10x20, grade 12.9, I assume any bolt with CoC meeting the spec will be acceptable? thanks

I guess they've been gunned up tight or I'm a weakling 😄 I've ordered a new compact impact gun to help, I should be able to get that on an extension into the transmission tunnel and hopefully free them off. Dewalt DCF921P2T-GB 609nm break away, so should be sufficient. Unfortunately Screwfix just called and told me their warehouse cancelled the order, and would I like to reorder. FML 😆. ETA an additional 4 days for that.

Hmm I’ve removed the brakes and drive shafts etc. 😪

The 'new' one is my original CC housing and CWP, when the Tracsport was fitted the original diff went to Road and Race Transmission for the Drexler. It's been sitting on my worktop since September 2023. I'm properly stuck sadly. I've removed the driveshafts. hubs and brakes, though the brakes are still attached via the handbrake cable. The plastic adjuster is seriously tight and I can't move it, the handbrake has minimal movement too. I figure with the diff out I'll have better access. Getting the diff out has come to halt as I just can't move the prop bolts. I'm working on axle stands so can't get a breaker bar on them. Any tricks for this, I'm at the point where I think I have to take the tunnel cover off to go in through the top, but since the handbrake is so tight I'll struggle getting the handbrake lever up to permit the tunnel cover to be removed. Going at the prop bolts from underneath is still probably the best idea, but I've run out of ideas on how to get them moving.

I don’t really want to get into naming the history of the current unit, as I’m happy with the servicing etc, and don’t want the thread to look like I’m having a knock at them. I made the decision and bought the replacement diff, so it’s going in. To me it made sense to have a spare being located on the island. Diff rebuilds due to shipping etc are a PITA.

Possibly, it was a complete unit. After it went in it was awful. My old final drive is in my original casing mated to a Drexler. Hopefully it will be reliable and back to similar noise levels. Though I can’t get the handbrake to slacken at the moment so it may have to stay for another season! 🤨

Surprisingly it f’ing noisy, road driving it’s awful. It was the only diff available just before a track day. It’s come it

Thanks, this isn’t the BMW diff as it’s on the 620R. Hopefully nothing needs replacing as a Tracsport went in last year, fitted by PGM, so I might try the short cut. If I can avoid releasing the drive nuts that would certainly be handy!

I need to reuse the carrier, the new diff isn’t in a carrier at present.

Morning All, I’m starting the process of swapping out my diff on the 620R, I’ve a shiny new Drexler to be fitted. I understand how to remove and fit the diff based on my experience building my 420R, but that’s basically a complete deconstruction of the rear end. Basically all hardware from Dedion, A frame etc gone. I’m wondering if there’s any short cuts to get the diff out, that will save me removing everything? Thanks

In the end I made my own solution using silicon hoses with some joints, it’s not great but better than forcing that stiff top hose. If CC has sorted it, I’d rather use a single length. Plus mine is now slightly more tricky to bleed as it raises over the cruciform.