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car won't move: bad gearbox, clutch or rear axle?

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jmsd65mgb Jed M
Elk Point, SD, USA   USA
Hey there, I have a 1965 MGB iv'e rebuilt and am finding a very big problem. I had separated the engine and transmission and the clutch assembly looked fine so I put it back together and the slave cylinder (new) has been bled and the clutch lever appears to be moving properly. I have the car on blocks now with the engine running but when I put the car in gear, the rear wheels don't speed up when you give it gas. You can stop the wheels from turning by hand when in gear! The wheels turn the correct direction when you switch from reverse to first gear and the driveshaft is turning but it's like either the clutch isn't catching the flywheel or somethings broken in the axle or gearbox. From the threads i've found here, I may have a half shaft issue. Any input on where to move next is appreciated, thanks.

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MT-B Avatar
MT-B Matt T
City, NY, USA   USA
Jed are you attempting to stop one or both wheels from spinning? If the car is up on blocks and both wheels are off the ground and you stop one with your hand the other will spin through the action of the open differential. Could this be what you are seeing? If you are able to stop both from spinning at the same time you have other issues to look into.

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allanreeling ALLAN R
RANDLAY, TELFORD, Shropshire, UK   GBR
Grab the prop. If you can stop it with hand pressure you have a box or clutch issue. If you can engage a gear without clutch, it's probably clutch or hydraulics. I'm not big on gear boxes but it seems the clutch is first recourse. Lack of pressure plate pressure, if that's what is the cause, could be the m/c or slave not allowing proper return and there are operating rods of different lengths I believe. Too long maybe?
Select a gear then remove the slave and see if you get proper drive then.



soonerv8

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ozieagle Avatar
ozieagle Gold Member Herb Adler
Geelong Victoria, Australia   AUS
1958 Wolseley 1500 "Wooly"
1966 MG MGB "Bl**dy B"
Matt X2

Herb



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Edited 1 time(s). Last edit at 2019-03-14 04:14 PM by ozieagle.

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GlennMGB Avatar
GlennMGB Silver Member Glenn G
Fort Worth, TX, USA   USA
1965 Triumph TR4A
1967 MG MGB GT "Rose"
You don't really know whether the car will move if you've got the rear axle in the air. Try putting it on the ground.

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jmsd65mgb Jed M
Elk Point, SD, USA   USA
Matt, I've only tried stopping one from turning, not both so I'll give that a try. I'm pretty sure the other wheel kept spinning when I stopped one. Looks like I need to do some research on open differentials. I assumed that regardless of whether the car was off the ground or not, the wheels should turn faster when you give it some gas while in-gear.

Allan, I will definitely try stopping the prop and see what that does. Hadn't thought of that. I assumed the SC operating rod was the correct length since I hadn't changed it but I can disconnect it and see if it engages. Yah, if it's too long, it wouldn't allow the clutch to engage.

Glen, I've completely removed the front and rear brakes so I'm keeping it up in the air until I know I can stop it, if need be. A car's drivetrain only works if it has the weight of the car to engage it?

Thanks for the suggestions, I'll give them a try and keep ya posted

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Basil Adams Avatar
About 12 miles from Sears Point, CA, USA   USA
The clutch plate may be in backwards. If the motor turns and you put the car in gear and the wheels don't engage, the clutch is not hooking up. Try everything else first because fixing that requires the engine to come back out. Best of luck. Basil 707.762.0974 basiladams@yahoo.com



Basil C. Adams
1956 MGA Coupe (Show Car)
1957 MGA Roadster (Driver)
1958 MGA Coupe (Racecar)
1959 MGA Coupe (unrestored)
1960 MGA Coupe (unrestored)
1960 MGA Roadster (Driver)
MKIII Elva Courier (E1056)
1967 427 Cobra
1972 Alfa Romeo Montreal
A coupla late MGBs
1960 Austin Healy BN7
More Cars than Brains

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ohlord Avatar
ohlord Gold Member Rob C
North of Seattle, N.W., USA   USA
1957 Land Rover Series I "EYEYIYI"
1971 MG MGB
1971 MG MGB "Bedouin 2"
Don't grab the prop of a running car in gear....
Yikes, I think I've finally heard it all



"I'm a long way gone down this wild road I'm on
It's gonna take me where I'm bound
It's a long way around"



"These are the days that must happen to you"

RD2 Radar/ Electronic Warfare Technician
Vietnam 1969-1972

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allanreeling ALLAN R
RANDLAY, TELFORD, Shropshire, UK   GBR
Two points there Rob.
!. The suggestion is there is no drive.
2. and pressure on a smooth prop shaft surface, in my opinion, will do no harm. Better than trying to stop the wheels!



soonerv8

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  malski thanked allanreeling for this post
dryden Avatar
dryden Clive Dryden-Chouen
Gloucester, Forest of Dean, UK   GBR
In reply to # 3909040 by ohlord Don't grab the prop of a running car in gear....
Yikes, I think I've finally heard it all

I am with Rob here,....most dangerous suggestion I have heard. Especially with gloves..!!!

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ghnl Avatar
ghnl Silver Member Eric Russell
Mebane, NC, USA   USA
1961 MG MGA "Calvin"
I agree - most likely you are seeing the effect of the open differential. And do not try grabbing a spinning prop shaft!

Try this (assuming the car is still up on jack stands): transmission in gear, engine off - now try turning the prop shaft. You should only be able to move it a few degrees due to play in the gears. If you can turn it around & around something major is wrong.



Eric Russell ~ Mebane, NC
1961 MGA #61, 1981 Alfa Romeo GTV6, 1984 Alfa Romeo Spider, 1991 Honda ST1100

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dpanza david panza
somerset, PA, USA   USA
1952 MG TD
1954 MG TF
May sound silly but ..did you check the fluids in the master and slave for the clutch??

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dpanza david panza
somerset, PA, USA   USA
1952 MG TD
1954 MG TF
May sound silly but ..did you check the fluids in the master and slave for the clutch??
Also make sure they are bled correctly..

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BlancoB Silver Member Robert H
San Marcos, TX, USA   USA
1969 MG MGB ~ For Sale ! ~
1974 MG MGB
The first time I rebuilt an engine and installed a new clutch, I put the disc in backwards. Never took it off the stands, just started over.

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riley1489 Avatar
riley1489 Gold Member Bruce H
Great White North, QC, Canada   CAN
1953 Jaguar XK120
1959 Riley 1.5 "King George"
1973 MG MGB
In reply to # 3908769 by allanreeling there are operating rods of different lengths I believe. Too long maybe?

we are forgetting that this a hydraulic system and push rod length has no bearing on the travel of the cylinder.

are we sure we can install practically a driven plate incorrectly? without interference to the crankshaft?



B



Check your ego Amigo!



Edited 1 time(s). Last edit at 2019-03-15 05:48 PM by riley1489.

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