tr7 box in sprint?

[pmn74]

Been reading 'bodger bens' site (link on maddmarts), bit on there about tr7 5 speed box in a sprint <!--EZCODE EMOTICON START :eek --><img src=http://www.ezboard.com/images/emoticons/eek.gif ALT=":eek"><!--EZCODE EMOTICON END--> ! Anyone shed any light on this conversion, anyone done it?

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[alun n]

Several folk have, but why would you want to?<br>
<br>
LT77 gearboxes are expensive (as they are sought after bt TR7 guys, Rover guys, sherpa guys (if there are any) and also the kit car guys. They lunch their layshafts fairly frequently and are expensive to mend. They are marginally heavier than a Sprint overdrive 'box. They also have an internal oil pump which means if you tow a car with one fitted you either have to have the wheels lifted or the prop disconnected or knacker the pump. i sold one on ebay a couple of years ago with a knackered layshaft (which was mentioned in the listing) and still made £150 on it<br>
<br>
Sprint 'boxes on the other hand are extremely rugged, come generally with overdrive and are often virtually given away on ebay. Good for much horsepower without modification, stronger springs needed in the overdrive if you are really going for it.<br>
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To fit an LT77 will entail changing the flywheel, clutch, clutch slave and hydraulics, possibly the starter motor (as the guys who have done it that I've spoken to did) and 'adjust' the propshaft. After all of this you lose overdrive and still end up with a final drive ratio of 1:1<!--EZCODE EMOTICON START :| --><img src=http://www.ezboard.com/images/emoticons/indifferent.gif ALT=":|"><!--EZCODE EMOTICON END-->

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[pmn74]

Cheers for that Al (wont be doing it then <!--EZCODE EMOTICON START :) --><img src=http://www.ezboard.com/images/emoticons/smile.gif ALT=":)"><!--EZCODE EMOTICON END--> ) On a side note, can i change my early sprint wheel studs to the later ones (7/16 i hear)? Do the studs go straight in the hub with no probs/mod? What about the splines on the studs, are they the same size (3/8 and 7/16)? And is it worth it? If so, could you tell me the sizes please i.e. total length, spline diameter etc? There's a chap on the bay who might have some, he needs the info, mmmmmmmmm...............................

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[dollyboy]

mr speedy has that box married up to a sprint lump in his spit. spit folk seem to like that set up for some reason, theres probably something technical behind it, and therefore I have no idea why.<br>
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<!--EZCODE EMOTICON START :rollin --><img src=http://www.ezboard.com/images/emoticons/roll.gif ALT=":rollin"><!--EZCODE EMOTICON END--> <br>
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(ok, the reason is that ive never demolished or even looked under a spit)

<p>project orange - slow progress<br>
project black - coming on, could be sold...<br>
project white - pimp my tolly, next year!</p><i></i>

[MaddMart]

The studs are a straight replacement, no mods required, although you will have to pull the hubs off to do the rear ones. Decent hub puller required or hydraulic press.

<p>Martin<br>
<br>
<!--EZCODE LINK START--><a href="http://www.dolomitesprint.com/" target="top">www.dolomitesprint.com</a><!--EZCODE LINK END--></p><i></i>

[pmn74]

cheers Mart <!--EZCODE EMOTICON START :smokin --><img src=http://www.ezboard.com/images/emoticons/smokin.gif ALT=":smokin"><!--EZCODE EMOTICON END-->

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[mr speedy]

I do indeed have that box on a sprint motor! Standard tr7 friction plate between sprint pressure plate and flywheel. TR7 backplate behind flywheel - the clutch slave mounting is different ( or did I just mod the old one?) As for mountings on chassis and shaft all I can say is it will all be wrong!!!!!! I had to widen the chassis to accept the TR7 box as it's wider than standard one.

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[Jon Tilson]

as most of what he said I'm sure is lifted from an earlier post of mine anyway...<br>
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Main problem is where to put the clutch slave, which on the TR7 is right where the rack is on a dolly. Steve Martin redid the clutch slave setup by drilling and making new bosses on the bell housing. Too much work when the Sprint box does the job perfectly well.<br>
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I can see the makers argument for the LT77 over the Triumph large car box. It must have cost about half as much to make...Its crap.<br>
The Rover box was already at its limit and no overdrive either.<br>
Jonners

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[alun n]

I thought your earlier post lifted what I had previously said on the CT forum...<!--EZCODE EMOTICON START :lol --><img src=http://www.ezboard.com/images/emoticons/laugh.gif ALT=":lol"><!--EZCODE EMOTICON END--> ...which thankfully is not supported by my Mac and Safari

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[Jon Tilson]

That great minds think alike...<br>
The LT77 box does actually improve the TR7 4 speeder but why that wasnt fitted with overdrive in the factory is a mystery to me...<br>
Early Coupes have a single rail 4 speed, late ones have a 5 speed and a bigger diff...Go figure! Okay the single rail box may have been marginal but the overdrive wasnt...quite happily coping with the Sprint.<br>
The Sprint box with overdrive would have fitted easlily too. <br>
It also improves the Rover V8 quite substantially...<br>
BTW the fifth gear ratio is a overdrive (step up) one...<br>
<br>
Jonners

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