charlie_pank Posted February 19, 2010 Share Posted February 19, 2010 Thinking about getting one today... Is the standard diff a sierra 7" diff? What type of LSD was fitted to Sierras? Eg Quaiffe, Titan etc... Ta back here because I want to be. Edited by - charlie_pank on 19 Feb 2010 10:57:04 Link to comment Share on other sites More sharing options...
Mark-G Posted February 19, 2010 Share Posted February 19, 2010 Give Phil a ring at Road and race *thumbup* Road & Race Transmissions The Bullock Shed Filston Farm Shoreham, Kent TN14 5JU tel: 01959 525105 mobile: 07836 333882 I had the new Titan LSD fitted and very happy with the service from them and does work a treat here Link to comment Share on other sites More sharing options...
charlie_pank Posted February 19, 2010 Author Share Posted February 19, 2010 Hi, thanks, I did ring Phil at R&R, but I'm looking at over 1k for the Titan, however, I can get a 7" 3.62 LSD from a sierra on ebay for 250 + P&P. Just trying to find out why I shouldn't back here because I want to be. Link to comment Share on other sites More sharing options...
Milesk Posted February 19, 2010 Share Posted February 19, 2010 Look at for an AP Suretrac - I bought one on ebay for £150 and Phill fitted it I think the Ratio you want is 3.92 I had 3.92 with 1.4ss and 6 speed box and it was great. I am know a 1.8 with 6 speed and I need 3.62 Hope this helps Link to comment Share on other sites More sharing options...
BYKer Will Posted February 19, 2010 Share Posted February 19, 2010 I doubt you want a 3.92 with an r1! unless you want to keep under 70. Simon has spotted a rare 3.1 on ebay which is what I think you will need unless an r1 is super high geared compared to blackbirds and busa's. Then get an lsd put in but sounds like it won't be cheap. Will Link to comment Share on other sites More sharing options...
charlie_pank Posted February 19, 2010 Author Share Posted February 19, 2010 3.62 gives me a top speed of 125mph at 12500 rpm, 3.3(4?) gives me a top speed of 133mph at 12500 rpm. Given how few track days I do, I'm happy to settle for a 3.62 as they're cheaper/easier to get hold of. My question was really about what kind of LSD was fitted to Sierras, on ebay it's unusual for diff sellers to give a lot of detail, so I wanted to know what I was buying if I bought a 'Sierra 7" LSD' from ebay... back here because I want to be. Link to comment Share on other sites More sharing options...
Beelzebub Posted February 19, 2010 Share Posted February 19, 2010 From memory the LS diff fitted to Sierra's was one of the viscous type. At least the one I had was. The joints where the driveshafts enter the diff are also different. The Sierra diff had output flanges & the driveshafts were secured using six bolts. There's a thread somewhere in the ancient scriptures covering this. D. Link to comment Share on other sites More sharing options...
neilg Posted February 19, 2010 Share Posted February 19, 2010 Charlie, for your ref my blackbird has a 6th gear of 1.64:1. The final drive is 3.38:1 I run 205/60-13 and this gives about 11 mph per thousand rpm in top. ie 11000 is 121 mph. It's about right. Any higher geared and it would feel abit long i think. Cheers Neil Link to comment Share on other sites More sharing options...
charlie_pank Posted February 19, 2010 Author Share Posted February 19, 2010 Thanks for the info R1 has a primary reduction ratio of 1.512 and 6th gear is 1.269 which I guess is why I need a different diff to a blackbird! back here because I want to be. Link to comment Share on other sites More sharing options...
BYKer Will Posted February 19, 2010 Share Posted February 19, 2010 Neil 1.64 ? are you sure mate! My book says 1.042 1.64 sounds more like third! I might be having a blonde moment due to the white wine but that to me suggests a blackbird at the sprocket is higher geared than an R1 Yours and my old blackbird caterham will easily top out in 6th with 206 60 13s on the back running I thought a 3.1 diff but maybe you are right at 3.34. W PS ordered that vest yet? Link to comment Share on other sites More sharing options...
charlie_pank Posted February 19, 2010 Author Share Posted February 19, 2010 I'm running 185/70/13 and have based my calculations on a circumference of 72.9" back here because I want to be. Link to comment Share on other sites More sharing options...
neilg Posted February 19, 2010 Share Posted February 19, 2010 Yeah mate, my spec sheet says 1st 4.35:1 2nd 3.14:1 3rd 2.48:1 4th 2.09:1 5th 1.84:1 6th 1.64:1 Final drive 3.38:1 God knows if that is correct but it is Issue 1 Date 18/07/00 Cheers Neil Link to comment Share on other sites More sharing options...
BYKer Will Posted February 20, 2010 Share Posted February 20, 2010 Neil and Charlie if you are interested. mmm I'm thinking about this a bit more whilst waiting for a sledging gold medal hopefully. These are my numpty thoughts post wine : A blackbird does have a 6th gear ratio of 1.04 However it also has a primary reduction gear of 1.571 which if multiplied together gives your 1.64 :1 By comparison a late model r1 has a 6th gear ratio of 1.269 as charlie says. However an R1 has a primary gear ratio of 1.512 which gives 1.91:1 Therefore at the sprocket 6th in an R1 is lower than 5th in a blackbird. This might not be an issue due to the higher revving R1 engine but I don't know and my head hurts now. Will Link to comment Share on other sites More sharing options...
Area Representative bluenose Posted February 20, 2010 Area Representative Share Posted February 20, 2010 My 'Bird is fitted with a 3.1 diff and it seems just right for road and track. Nick Lava Orange Caterham Blackbird Link to comment Share on other sites More sharing options...
sjmmarsh Posted February 20, 2010 Share Posted February 20, 2010 - just to get all the GTKY:CSR posts together..... Link to comment Share on other sites More sharing options...
RD Posted February 21, 2010 Share Posted February 21, 2010 Steve, have we started something here then ...... Plenty more ideas for the Club to come Rob Link to comment Share on other sites More sharing options...
charlie_pank Posted February 21, 2010 Author Share Posted February 21, 2010 What's this got to do with GTKY CSR? back here because I want to be. 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