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tips, technology, tools and techniques related to vehicle driveline components

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coolmg
Mark Cooley

(15 posts)

Registered:
06/22/2008 08:02AM

Main British Car:


T5 gearing question
Posted by: coolmg
Date: May 11, 2009 11:13AM

I have a sick T5 that will need removing and rebuilding very soon, I have an opportunity to receive a newly rebuilt T5 for payment for a recent job I completed. The question is my current T5 has a .73 final ratio the new one has a .63 and the rear gear is 308, at 80 MPH the engine turns 2600. I know the .63 will decrease the revs to around 2300 at 80 , do you guys think this is a negitive/positive or makes no difference? The engine is a 215 at around 200 HP the body is a 1980, looking for an openion.


Bill Young
Bill Young
Kansas City, MO
(1337 posts)

Registered:
10/23/2007 09:23AM

Main British Car:
'73 MG Midget V6 , '59 MGA I6 2.8 GM, 4.0 Jeep

authors avatar
Re: T5 gearing question
Posted by: Bill Young
Date: May 11, 2009 12:30PM

Mark, it's hard to say. A lot depends on your engine and it's torque curve and the rear end you're running. If you're getting any sort of "lugging" now when in 5th it will be worse at the same speed. Most V8s have enough torque to pull that type of gear ok though. I wouldn't be as concerned with the rpms at 80 as I would a 65 to 75 where you would probably do more driving. It's there that you want to be in a rpm range that won't lug down the engine.


MGBV8
Carl Floyd
Kingsport, TN
(4511 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB Buick 215

authors avatar
Re: T5 gearing question
Posted by: MGBV8
Date: May 13, 2009 06:14PM

What is the rpm drop from 4th to 5th with the .73? It will be greater with the .63. With a 3.08 rear gear I'd be looking for .80 5th gear.

Play with Dan Master's gear-ratio-to-road-speed-at-rpm calculator to see the difference:

[www.britishv8.org]


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