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s16034b
Bob King
Clarkston, MI, USA
(6 posts)

Registered:
11/27/2014 11:24AM

Main British Car:
1975 MGB Roadster Rover/Buick 3.6L

MGOC 3.07 Crown Wheel and Pinion
Posted by: s16034b
Date: April 17, 2019 06:19PM

Decided to retain the “B” axle in my Rover V8 conversion (primarily because of the wire wheels) and after 5 years decided that the 3.90 ratio doesn’t suite the V8 when used with the LT77 transmission- first gear is pretty much useless. So I purchased the MGOC British-made gearset that doesn’t require the differential to be machined. Won’t say from where, because it isn’t their fault....
This gearset is made by Sovereign Gear and appears to be of very good quality; it uses a 34/11 tooth count to achieve a 3.09 ratio with the 4cylinder differential. Has anyone installed one of these sets? The difficulty with the one that I received is that the pilot diameter for the crown gear is .022” too small to fit the differential.
This will require the pilot area of the differential to be machined, which is what I was trying to avoid. Could have bought the 3.07 set from Clive Wheatley and saved some cash.


mgb260
Jim Nichols
Sequim,WA
(1973 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: MGOC 3.07 Crown Wheel and Pinion
Posted by: mgb260
Date: April 17, 2019 07:20PM

Never heard of that one. Basil and Robert Kirk on the Mgexperience board sell the 3.07 made in Germany that requires no machining. May be the same one Clive Wheatley sells. I have heard those gears require more back lash than stock or will whine. Ford 7.5 and 8.8 require more also.


s16034b
Bob King
Clarkston, MI, USA
(6 posts)

Registered:
11/27/2014 11:24AM

Main British Car:
1975 MGB Roadster Rover/Buick 3.6L

Re: MGOC 3.07 Crown Wheel and Pinion
Posted by: s16034b
Date: April 18, 2019 08:18PM

Clive Wheatley’s gearset is a reproduction of the original MGC/MGB V8 gearset, which requires the different differential case. Or machining.215” of the 4cylinder differential. I contacted him prior to purchase of the “no machining required “ set.


s16034b
Bob King
Clarkston, MI, USA
(6 posts)

Registered:
11/27/2014 11:24AM

Main British Car:
1975 MGB Roadster Rover/Buick 3.6L

Re: MGOC 3.07 Crown Wheel and Pinion
Posted by: s16034b
Date: April 27, 2019 09:30AM

After machining the differential case pilot to match the ring gear inner diameter, the rest of the installation went smoothly, and seems quiet. Explanation that I received from the gearset manufacturer is that possibly a machining step was missed (although that seems unlikely as I would think that would be the register during machining).


mgb260
Jim Nichols
Sequim,WA
(1973 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: MGOC 3.07 Crown Wheel and Pinion
Posted by: mgb260
Date: April 27, 2019 01:38PM

Bob, do you know your backlash setting for those gears?


s16034b
Bob King
Clarkston, MI, USA
(6 posts)

Registered:
11/27/2014 11:24AM

Main British Car:
1975 MGB Roadster Rover/Buick 3.6L

Re: MGOC 3.07 Crown Wheel and Pinion
Posted by: s16034b
Date: April 28, 2019 07:39AM

When I contacted Sovereign Gears, they said .003-.005” backlash. Mine had about.002” variance, and I was able to get the tight spot at .003” and the loose spots at .005”
They specified the pinion depth to the front face of the pinion (where it abuts the bearing and depth shim) at 3.780”, which required a .212” spacer in my case with new bearings. This depth is the same as the OE gearset. The OE setup references the rear of the pinion, so the special tools may not be accurate.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5812 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: MGOC 3.07 Crown Wheel and Pinion
Posted by: BlownMGB-V8
Date: April 28, 2019 09:52AM

That's pretty tight. Most R&P sets use about .010", but you have to go with the manufacturer's spec if you expect to get the contact pattern right.

Jim



s16034b
Bob King
Clarkston, MI, USA
(6 posts)

Registered:
11/27/2014 11:24AM

Main British Car:
1975 MGB Roadster Rover/Buick 3.6L

Re: MGOC 3.07 Crown Wheel and Pinion
Posted by: s16034b
Date: April 28, 2019 09:07PM

Pattern looked pretty good and it is quiet, so a guess it is correct. Never have seen a manufacturer specify that tight a backlash either. Most of the Jeep axles I am familiar with are .005” minimum (Dana 35/44).


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