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MG MGB GT V8 Factory Originals Technical - Drive (prop) shaft angle

Drive shaft angle: I have a factory V8 and I converted it to a SD1/TR8 five speed the engine is mounted with factory engine mounts and Iím not using the Roger Williams Modified trans cross member with cotton reel mounts I have made a plate and a trans mount for a Chevy so I didnít have to move the cross member mounting location. I havenít finished mounting it to the cross member because Iím worried about the drive shaft angle. I havenít seen anything posted here about it. The pictures Iíve seen look like the remote
shifter housing is near the top of the gearbox tunnel which makes the gearbox flange pretty high and the angle steep. It is a 1975 car the front of the tunnel has been raised for the gearbox to clear. Can someone give me a measurement from the top of the tunnel to the remote shifter housing or any info. on what you did

Thanks,
Bob
Bob Fisher

Bob, since no one has answered. Your question may be a little too specific. V8 conversions are all a little different.
I have read that the angle of the drive shaft at the gear box should be the same as the angel at the differential, other wise you get harmonic vibration. I have never noticed this, but I might have simply got lucky and I will defer to the experts on this one. You can buy angle adjusting shims to go under the axle spring perches if you notice any bad vibrations, or if you just want to!
That is the angle measured at ride height, not "up in the air hanging on the bounce straps" height.
I did not use an SD1 Box, I used a Toyota Supra Box. Similar problem, except opposite, about an inch shorter smaller not longer taller. The SD1 box is 20mm longer than the MGB box, and the MGB gear lever is offset to the left of centre about half an inch.
I put the gearbox as High as possible at the back, leaving barely enough room to get the inner rubber boot on, where the lever exits the box. Because the base of the lever was high this gave enough room for gear lever movement. If I had set it low the lever movement would have been obstructed by the relatively offset gear lever hole. The outer MGB rubber boot accommodates the offset easily and you don't even notice it. It will not matter too much how high. So long as your SU's or efi, alternator etc have enough bonnet clearance and (too low) your tail shaft clears the heal board brace at the back of the tunnel. Not that even this matters too much, after all at ride height the thing will locate about five inches higher up. I had to use the shorter Chrome bumper style bounce straps.
Other options are to move the gear lever plate back and to the side or put a dog leg into the gear lever. I believe that the RV8 lever had such a dog leg, not sure though. Check with the RV8 guys.
I would suggest that you deal with the gear lever/tunnel clearance problems an then angle shim adjust if necessary.
Peter

Bob,

I can't give you any measurments, but I can give you the rules:

The centerlines of the engine and the pinion must be parallel but not coincentric. ie, if the engine centerline slopes downward at 3 degrees, the pinion must slope upward at 3 degrees. However, the centerline of the engine must not line up directly with the centerline of the pinion - there must be some offset.

If you have the january issue of the British V8 newsletter, there is an article on that. Also, check out http://www.streetrodderweb.com/tech/0203sr_drive_shaft_angles/index.html
Dan Masters

Peter & Dan thanks for the info.

Bob
Bob Fisher

Bob,

Even in a 75 shell you will still need to raise the tunnel roof to get clearance for the LT77 G/Box, it's a while since I did mine and i can't find the drawing I had, perhaps someone else can chip in with accurate dimensions.

Kevin.
Kevin Jackson

Kevin,

I did raise the tunnel.

Bob
Bob Fisher

Bob,

I may have missunderstood your post as you said "front of tunnel" if this means the area directly behind the radio console then you should be ok.

Kevin.
Kevin Jackson

This thread was discussed between 17/09/2007 and 19/09/2007

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