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  1. #11
    Join Date
    Sep 2007
    Location
    Hilperton,Wiltshire
    Posts
    2,523
    Changing to 5 speed won't increase your fuel consumption that much and considering how much it will cost you to change it. Your choice.

    Andy

  2. #12
    Join Date
    Jan 2017
    Location
    Mansfield, Notts
    Posts
    89
    Quote Originally Posted by Darnpistonbroke View Post
    I am currently running a Saginaw 4 speed which is agricultural to say the least. On a run without the fifth gear I average about 13 mpg!
    Maybe you also need to review the differential ratio ?

  3. #13
    Join Date
    Jan 2017
    Location
    Mansfield, Notts
    Posts
    89
    I've seen 2nd hand T5's sell for over £1000 but buyer beware and I wouldn't be buying one with out it's ID tag still attached as that's the easiest way of identifying exactly what it's intended application is. They are not all the same. Also the World Class T5 is the one to look for. There is also a difference in the gear ratios some have a higher more desirable 5th gear.

    I've just replaced the T5 in my car for a 6 speed T56 (not the same as the newer Magnum T56) I wasn't very impressed with the gear shift on my T5 even with a quick shift. Also I found a lot of play in both the input and output shafts which for a gear box that has only done 22k from new isn't great. I suspect the car has had more than its fair share of abuse by a previous owner. The T5 is supposed to be good for 300bhp. Though there is a modification that can be made to make it stronger.

    The newer tremec built T5's have had improvements made to them over the years and I believe are a better gearbox than older Borg Warner built gear boxes.

    You can buy a new T5 for around £2000 https://roadcraftuk.co.uk/index.php?...product_id=748

  4. #14
    Join Date
    Aug 2007
    Location
    Bournemouth
    Posts
    101
    That's a really good link. Thank you.

    The rear end is a 3:07 which is quite a tall final drive anyway. I think most cars run a 3:31 or a 3:54. A 2:88 I think would be too tall unless I stick with the 4 speed.
    Life is driving the Cobra. The rest of the time is just waiting.

  5. #15
    Join Date
    Aug 2007
    Location
    Bournemouth
    Posts
    101
    Legendary 427, sorry I don't know your name.
    Tried to PM you but it bounced back. Would like to have a chat.

    David.
    Last edited by Darnpistonbroke; 13-07-19 at 11:44 AM.
    Life is driving the Cobra. The rest of the time is just waiting.

  6. #16
    Join Date
    Jan 2017
    Location
    Mansfield, Notts
    Posts
    89
    Hi David,

    I've been on this forum a while but only joined the Cobra Club a couple of days ago so assume that's why I can't update my avatar and you can't PM me ?

    My mobile is 07842 809294.

    Regards

    Pete

  7. #17
    Join Date
    Sep 2007
    Location
    Hilperton,Wiltshire
    Posts
    2,523
    This forum and The Cobra Club we join are totally different.


    Andy

  8. #18
    Join Date
    Mar 2004
    Location
    Nr Salisbury Wiltshire
    Posts
    896
    Hi David, I have a Jag Getrag 5spd & it's been reliable for the past 20yrs, the hard part is finding one as most XJ12s are auto, also if you go the route of BMW Getrag (more common) make sure it has the detachable belhousing as some are cast all in one, I think some BMW (if not all) are dogleg 1st gear ! Steve
    AK 427, Chevy 350, Jag Getrag

    If you can make it - MAKE IT!

  9. #19
    Join Date
    Aug 2007
    Location
    Bournemouth
    Posts
    101
    Hi Steve. I've been looking at those. The 265 seems to be the one to go for but these are getting rather scarce. The 290 has a fixed bell housing which is a shame as it looks like these can take good power and torque.
    The annoying thing is a few years ago I had a 265 which I let go for £100! Not my best decision.
    Life is driving the Cobra. The rest of the time is just waiting.

  10. #20
    Join Date
    Mar 2004
    Location
    Nr Salisbury Wiltshire
    Posts
    896
    I feel your pain on that sale, I had a Jag Getrag that I bought from a scrapyard as a spare whilst searching for a different box for the brother in laws Cobra, I got it from a pile of random boxes for £30 as it had the offside mounting lug broken off!
    In the end my B-I-L persuaded me to sell it to him as we couldn't find a match for his, it was a perfect fit using the rear damper mounting instead of the side lugs...He got a good cheap box & I lost out, gutted!

    Steve
    AK 427, Chevy 350, Jag Getrag

    If you can make it - MAKE IT!

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