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Thread: 2500M Overdrive options

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    2500M Overdrive options

    I'm looking for suggestions/ideas for overdrive options (or a 5 speed) for my 2500M. It has the stock TR6 drive train & I'd like to make it more highway friendly. Any thoughts & suggestions will be appreciated.
    ps I'd like to keep the TR6 engine.
    1971 MGB GT
    2004 C4 Corvette Convertible

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    Yoda swift6's Avatar
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    Re: 2500M Overdrive options

    There are three options that I know of for a TR6. Depending on just how much room there is in the TVR all three should also work for you. One is using a Toyota based 5 speed with an adapter kit also which can be found hereHVDA Kit , another is a Ford T-9 kit that can be found at Quantum Mechanics and the last is using a T-5 transmission with a kit put together by Dupont Machining . I believe the T-5 offers the greatest range of choices in the overdrive gear.
    Shawn
    TR8FHC-Melted


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    Re: 2500M Overdrive options

    Shawn,
    Excellent input.
    Thanks, Ralph
    1971 MGB GT
    2004 C4 Corvette Convertible

  4. #4
    vagt6
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    Re: 2500M Overdrive options

    OF course, a Laycock J-type overdrive would be "correct" for your TVR, although I don't think TVRs came with OD.

    Not sure if the longer OD gearbox would fit in the chassis, either. Anyone ever put OD in a TVR?

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    Luke Skywalker
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    Re: 2500M Overdrive options

    OD was an option starting with the 2500 Vixen. I have restored TVR's fitted with OD...makes a much better car to drive on freeways. Only difference is the Lucas relay fitted to the bulkhead near the steering column.
    Cheers,
    D.
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    D.
    "If it's got t*ts or tyres, you've got problems"
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    Re: 2500M Overdrive options

    Would you recommend the overdrive or a 5 speed conversion? Any advantage to either approach?
    1971 MGB GT
    2004 C4 Corvette Convertible

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    Luke Skywalker
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    Re: 2500M Overdrive options

    I would fit a J type in order to keep the car correct.
    Cheers,
    D.
    Cheers,
    D.
    "If it's got t*ts or tyres, you've got problems"
    www.englishmotorsatfairbrook.org
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    Re: 2500M Overdrive options

    Agreed. Assume there is enough room to fit the unit w/o major modifications?
    1971 MGB GT
    2004 C4 Corvette Convertible

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    Luke Skywalker
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    Re: 2500M Overdrive options

    Fab trans mount, shorten the prop-shaft, fit relay, switch and wiring.
    Cheers,
    D.
    Cheers,
    D.
    "If it's got t*ts or tyres, you've got problems"
    www.englishmotorsatfairbrook.org
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    Yoda swift6's Avatar
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    Re: 2500M Overdrive options

    Shouldn't have to shorten the propshaft to use a J-Type. The mounting flange for the driveshaft should be in the same location. The OD replaces the tailhousing of the non-OD transmission. The OD and non-OD transmissions did use different mainshafts and getting all the parts to convert a non-OD transmission into an OD transmission can be time consuming and troublesome. The best and easiest bet is to buy an OD transmission complete. Are you sure the rear mount would even need to be changed? The mounts are the same in the TR6 in OD vs non-OD cars (they change between A-Type and J-Type OD's).

    The advantage to a J-Type, other than keeping it closer to stock or at least a stock option, is that you can use overdrive in 3rd as well as 4th gear giving a 6-speed gearbox. The downside is that if the relay fails, which isn't uncommon, no more overdrive until it's replaced. Worse, if the overdrive is still engaged and you reverse the car, it will blow the overdrive clutches and it will need to be pulled and rebuilt. Luckily, there are options available out there to automatically disengage the overdrive whenever the transmission comes out of a gear into neutral so it can't be accidently left in overdrive.
    Shawn
    TR8FHC-Melted


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    Luke Skywalker
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    Re: 2500M Overdrive options

    You maybe right about the propshaft, as I vehicles that I worked on where already fitted with an OD...just trying to think of things that may need to be sorted. I do agree that it is easier to purchase an OD already built, but the bits are about to buy seperatly.

    The rear mount is a simple piece of flat stock.

    I run three different vehicles fitted with a Laycock OD. One being my one ton tow vehicle. I never reverse with the OD engaged, bad habit with any OD. As far as the relay goes, the same relay is used on Jaguar's for horns and fans for many years.

    The car will be a joy to drive if it has an OD fitted.

    Thank you for your input, Shawn!

    Cheers,
    D.
    Cheers,
    D.
    "If it's got t*ts or tyres, you've got problems"
    www.englishmotorsatfairbrook.org
    TVR Car Club North America Southwest Regional Organiser

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    Re: 2500M Overdrive options

    I've got OD on my MGB and would not go without it. I'll probably go w/ the Laycock unit. Look forward to the conversion. I enjoy my 2500M and the OD will make it that much more enjoyable.
    Thanks to all for the input.
    Ralph
    1971 MGB GT
    2004 C4 Corvette Convertible

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    Yoda swift6's Avatar
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    Re: 2500M Overdrive options

    Glad to help anyway that I can, I always stop into this forum and read up. I still hanker after a 2500M every now and again.
    Shawn
    TR8FHC-Melted


  14. #14
    Luke Skywalker
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    Re: 2500M Overdrive options

    That is a GREAT motor! The best of every thing that TVR had...great fit at the doors and the body was at last built for every day use. Ralph, get to it! You will not reget the switch.
    Cheers,
    D.
    Cheers,
    D.
    "If it's got t*ts or tyres, you've got problems"
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