MGB & GT Forum

I have a 73 MGB and I'm looking to swap out my 4 speed for the best 5 speed option and I'm looking for advice on choices.

Lots of discussion already. Search.

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Semi retired Auto Electrician with over 44 years experience. Specializing in pre 1975 car electrical systems. Trained on early Lucas, Bosch and Magnetti Marelli systems.
Australian Auto Electrician actively rebuilding and calibrating early Lucas and Delco Remy 1/2/3 bobbin regulators, Lucas generators/alternators (including 3rd brush and generator/starters) and magnetos. Large supply of original Lucas 1960 and 1970's parts to suit British cars (assembled and/or exported).

Available for guidance/assistance via email.

Be warned......I'm an grumpy old fart. I take no **** from people too lazy to do a preliminary search of the forum or google so therefore don't deserve my time.
Nor do I appreciate wasting time providing suggestions towards a solution to then have you ignore them because you have to do some actual investigative work, in favour of a possible solution from a knowall friend of a friend of a friend who once upon a time was a gardener with a shifting spanner and a set of pliers and somehow pretended they'd fixed their glowing ignition lamp with a piece of surgical tape, speck of moon dust, a scratch of their arse and a rusty razor blade.

And having said that, please don't mistake me for someone who even remotely cares what you think.

WHy not just get a good OD transmission? Flipping that switch and dropping the revs is miraculous. 80mph at about 2600 rpm in a 44 year old car. Just saying.

Hi-Gear has kits for T-9 5-speeds

http://hi-gearengineering.co.uk/content/view/15/30/

Vitesse has new Mazda 5-speeds

https://www.vitesse-ltd.com/products/vitmgb251

My '74 GT now has a T-9, and I like it quite a lot. Should have gone for the different 1st gear - the one I have is pretty short - didn't know about it then.

Harry

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"If you can't be kind, at least have the decency to be vague."
Unknown

"Some cause happiness wherever they go; others, whenever they go."
Oscar Wilde


1974 MG BGT - Green Mallard, Acme Speed Shop engine, Schlemmer dist, T-9 5-speed
2008 MINI Cooper Clubman - Mellow Yellow w/ silver top

80@2600???
What diff are you running?

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Semi retired Auto Electrician with over 44 years experience. Specializing in pre 1975 car electrical systems. Trained on early Lucas, Bosch and Magnetti Marelli systems.
Australian Auto Electrician actively rebuilding and calibrating early Lucas and Delco Remy 1/2/3 bobbin regulators, Lucas generators/alternators (including 3rd brush and generator/starters) and magnetos. Large supply of original Lucas 1960 and 1970's parts to suit British cars (assembled and/or exported).

Available for guidance/assistance via email.

Be warned......I'm an grumpy old fart. I take no **** from people too lazy to do a preliminary search of the forum or google so therefore don't deserve my time.
Nor do I appreciate wasting time providing suggestions towards a solution to then have you ignore them because you have to do some actual investigative work, in favour of a possible solution from a knowall friend of a friend of a friend who once upon a time was a gardener with a shifting spanner and a set of pliers and somehow pretended they'd fixed their glowing ignition lamp with a piece of surgical tape, speck of moon dust, a scratch of their arse and a rusty razor blade.

And having said that, please don't mistake me for someone who even remotely cares what you think.

PM Sent

As suggested earlier fit an OD. If you get a UK spec set up you’ll have 6 gears not 5.

I don’t actually know, I just acquired the car and the PO wasn’t very helpful with details. I am wondering if the speedo isn’t somewhat optimistic, anecdotally based pn the number of cars passing me on the autoroute. I’ve tried validating against some of those roadside speed awareness signs but the needle wavers at low speed so until I get the cable sorted it’s pretty hard to draw any conclusions.

I had a T9 conversion and loved it. I liked it much better than the O/D and if I had to make the choice again it would still be my choice again. Downside is cost-a good factory O/D can be had both easier and cheaper

The Datsun 280 z conversion from Riverfate is nice, easy and relatively affordable. I took out an overdrive to put one in my car, and for me it works much better. Better gear spacing and it's a more efficient box getting just a bit more power to the wheels

Robin,

Two tips:

1. I used a GPS Navigation device to confirm my speed while adjusting my speedometer. Necessary after changing the face plate.

2. Pull the speedo cable out of it's sheath. Clean cable & give it a good lube -- except for the final 6 inches at the gauge, don't need oil inside it.


John D

Did you change the diff?

FWIW, MGB overdrive provides a drive ratio of .82:1, representing an 18 percent reduction in engine speed for a given road speed...

Dick

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Errabundi Saepe, Semper Certi
(Often wrong, but always certain)

If you do go this option, could you settle a suspicion of mine? Apparently getting a transmission from a 280Z is getting harder to do. However, I suspect but cannot confirm that the Nissan transmission needed for the Rivergate swap, the FS5W71C, is actually readily available from other applications. More importantly, one application, the 720/D21 truck, uses the same gear ratios as in the 280Z. Both the 280Z and 720/D21 four cylinder versions use variants of the Nissan L-series engine block (the Z-series and KA-series) with the same bell housing and clutch pilot. Four-cylinder, five-speed, two wheel drive 720/D21s used the same transmission with the same gear ratios for all of 1983-1997 at least.



Edited 1 time(s). Last edit at 2018-06-30 12:01 PM by theycallhimart.

Thanks, I am planning to do just that but got fed up feeling around with my arm jammed up in the dash so have focussed on some easier stuff first. The wavering speedo needle was a common problem with older cars when I was working in a garage in the early 70’s. As I recall my Pontiac convertible had so much space under the dash I could actually see what I was doing and get both hands up there. I just got my really cool new bluetooth endoscope yesterday and plan to tackle the job with a panoramic view on my iPad. It probably won’t help with the bruising and scratches but should make quicker work of the job.