Sjwarden Posted January 3 Share Posted January 3 Been lurking on this site and dreaming of a Caterham for years. Finally got one a week ago. Planning on doing some maintenance and checks over the winter, and preparing for a lot of miles come better weather. My new car is a kit that was assembled here in the States in 1999, a super seven K series car with the 1.8 VVC engine and Caterham’s 6 speed gearbox from that time. It is also fitted with an LSD. I have a VIN SDKLDKANSX0010168. Wondering what gear oil I should use to top off the diff in this vehicle but I cannot figure out what type of LSD it has. Does anyone have any ideas? Unfortunately the VIN plate has no info other than the VIN number on it. Thank you for any help or input. Link to comment Share on other sites More sharing options...
MV8 Posted January 3 Share Posted January 3 If it were a clutch type LS, a friction modifier additive would be needed. Otherwise, you can use the normal diff oil. I'm guessing it has a Quaife ATB. You can check with a $20 usb probe camera through the filler (they have a built in adjustable brightness light). They went to BMW diffs around 2010. Prior to that, all are supposed to be 7". Probably a 3.62 or 3.92 ratio but ratios from 3.14 to 4.70 are also available. Link to comment Share on other sites More sharing options...
Croc Posted January 3 Share Posted January 3 8 hours ago, Sjwarden said: Wondering what gear oil I should use to top off the diff in this vehicle but I cannot figure out what type of LSD it has. Does anyone have any ideas? Unfortunately the VIN plate has no info other than the VIN number on it. Thank you for any help or input. Congratulations on your new acquisition and welcome to USAS7. Sadly it is a little cold right now to have a good play with it but Spring will be here shortly. There are a number of other Rover-engined car owners on USA7s so don't think you are alone if you are confronting engine questions and need technical input. I think MV8 is right. If original then I expect it is a Ford Sierra diff housing with Quaife internals for a 1999 car. I assume you did the usual test to confirm LSD - on a lift, rotate one wheel, etc.? I would not top off the diff oil. I would drain/suck out what is there and give it all new fresh oil. I have never been a fan of mixing old unknown oil with new stuff. For spec, I would look up one of the Rover assembly manuals of a year near to your build year in the library on this site and see what they recommend for diff oil spec - you can get a match to a quality brand available in the USA. 2 Link to comment Share on other sites More sharing options...
coffee break Posted January 3 Share Posted January 3 Send a sample of the oil to be analyzed and see if there any friction modifiers in it. Link to comment Share on other sites More sharing options...
Sjwarden Posted January 4 Author Share Posted January 4 Thank you all for the suggestions and advice. I did go ahead and buy a boroscope, should come in handy. I did also check the rover assembly manuals and they refer to the owners manuals for the oil specs. I found an owners manual that seems close in year to mine and I think in combination with a boroscope to verify the diff type I can nail this down. Also might send away for an oil analysis as coffee break suggested. 1 Link to comment Share on other sites More sharing options...
slowdude Posted January 4 Share Posted January 4 As croc has mentioned. Most likely a sierra diff. That k series will be a riot. I think we may have enough people now for a bulk deal on oil filters from discount mg rover spares. Enjoy! (And don't forget to rev that motor out). Link to comment Share on other sites More sharing options...
jbcollier Posted January 4 Share Posted January 4 You just need to figure out what kind of LSD diff you have and get the oil to match. Testing the oil you have might be useful to catch any developing issues but there is no guarantee that the PO used the right oil. If it is a torsion diff, raising one wheel off the ground and seeing if it spins proves nothing. Link to comment Share on other sites More sharing options...
Sjwarden Posted January 11 Author Share Posted January 11 Ok, reviving this thread a bit. Thank you for all the help so far. In an effort to nail this down so I don't accidentally put the wrong oil in and ruin this diff I got some more info. I took the suggestion above and purchased a camera probe with light. Got the attached pics of the external diff housing and some of the inside. This inside pics are terrible so not sure anything can be made of them. Outside appears to be Ford Sierra diff as mentioned. Also, if this helps, when jacked up and rotating one rear wheel, the other wheel also turns in the same direction. Diff oil appeared nice and amber and clean, but I assume that is because the car hasn't been driven in about 2-3weeks. Diff drain/fill plug was a 10mm Allen and it was magnetic. There was a few black metal filings attached on the inside magnet that I cleaned off. I might try and get a few more pics of the inside and push the camera deep into the oil, but I thought this might be enough for a firm opinion on diff type. Link to comment Share on other sites More sharing options...
Sjwarden Posted January 11 Author Share Posted January 11 I made a video that might help. With wheels turning you can see the diff turn. e7d68373bbfc918c574327ab0b40bb36.MP4 Link to comment Share on other sites More sharing options...
jbcollier Posted January 11 Share Posted January 11 Jack up the rear on one side until the wheel on that side is clear of the ground. Try to turn the wheel off the ground. If you can spin it easily, or with moderate effort, then it is either an open diff or a Quaife (Torsen/ATB) diff. Either of these will run just fine on regular gear oil. If you can't spin the wheel, or it takes enormous effort, then it is a LSD diff. You can still use regular gear oil but you may also need to add a "LSD friction modifier". Link to comment Share on other sites More sharing options...
MV8 Posted January 12 Share Posted January 12 Looks like a quaife lsd to me. An open diff looks very different as a dark iron casting with big windows exposing the side gears and spider gears. Clutch types (that would use friction modifier additive) usually have windows to access the clutches behind the gears. Link to comment Share on other sites More sharing options...
bsimon Posted January 19 Share Posted January 19 (edited) I went out to the shed and looked through my box of spares. The diff really looks like an AP Suretrac. Early in the video you can see pry slots next to the left bearing. Quaife doesn't have pry slots. The turned surface later in the video shows an unbroken smooth surface. Quaife has 5 or 6 drain holes that you would see progressing by in the video. Caterham offered AP Suretrac upgrade during the period of time that the K engines were used. It may have been standard fare for the fancier K models like R400 and such. Suretac is a cam and pawl "Chicklet" style ATB device, very similar to the cam and pawl unit that Hewland used in FT200 and other gearboxes, only more advanced and complicated. Very good strong devices unless you are contemplating outlandish HP levels. The only other diff might be an original Ford viscous limited slip. I've never seen one in the wild, so I'm not sure what they look like. Edited January 19 by bsimon 1 Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now