Clutch/gear change problems

[Bobble]

Some help with gear changing please.

 

I obtained my 1965 TR4A about 18 months ago and have now completed full body restoration and driving it on a regular basis. Right from the start I have had difficulty with selecting gears - especially second. I have to push the clutch pedal to the floor in order to change a gear and it "bites" as soon as I begin to lift it making initial pulling away quite sharp at times. I have had new master and slave cylinders fitted and replaced all the fluid - the system has been bled and adjusted twice. The mechanic tells me that if he adjusts it any further it will cause problems with the release bearing. I am pretty sure that I now need to replace the clutch assembly but I would have thought that a worn clutch would cause the clutch to (dis)engage earlier rather than right at the end of its travel. Is my thinking correct here and am I right to consider a clutch replacement? My left leg is developing bulging muscles from the effort that it takes to press the pedal - I had hoped that this would improve with regular driving but it is not proving to be the case.

 

One other point. Before the body restoration TRGB replaced the overdrive with a reconditioned unit. There is now considerable "slip" in third overdrive and any attempt at reasonable acceleration results in the engine gaining speed (rev. counter zooms up) without any real incease in road speed. Would this be clutch related too? I've never fully understood how overdrive works so I don't know if a dodgy clutch would affect overdrive too. Why woud it happen in third and not fourth (athough I do have to let overdrive "settle" in fourth before zoomng off)?

 

Different thread or can I ask another question here?

 

On take off I always get a "clunk" that sound too hollow to be a drive shaft - it sounds a bit like someone knocking a club against the petrol tank. The car has a new prop shaft also fitted by TRGB. Any ideas?

 

Many thanks

 

Bob

 

PS I have owned a MGB Roadster (1969) for almost 40 years but I have gained more knowledge of the workings of TR4s in the last eighteen months by reading this forum than I have accumlated from lengthy MG ownership - well done.

 

 

[RogerH]

Hi Bob,

there is clutch inside the OD, this could be slipping. However if TRGB had fitted a recon unit then I would be very surprised.

 

Is there any 'clutch' slip when in 4th nut OD NOT selected (low speed, bags of power see what happens).,

 

Regarding the 'normal' clutch - make sure that every joint (pin and hole) is as perfect as it can be.

ANY slack ANY where will cause lost TRavel at the slave.

 

Roger

[MKTR]

Hi Bob,

 

I am sure that you will get a number of replies with possible solutions but I had a similar issue with gear selection not so long back. Adjustments, master/slave cylinders etc did little to correct it, however, when I had to take the gearbox out for another reason I found that the bolt/pin holding the clutch release bearing fork had sheared. This meant that there was some rotation on the rod before the two end of the pin locked and enabled the bearing to move forward. I do not know why it was mainly in 1st & 2nd gear but it has now been sorted.

 

Mark

[boxofbits]

Hi Bob

 

A faulty clutch can either slip or not disengage properly. Normally the clutch cover goes faulty, so you'd have to replace it.

 

With regard to slip in overdrive, if you switch out of overdrive and give it some welly straight away does it still slip? If it grips well then its probably an overdrive fault, though probably best to test with a new clutch first to rule that out.

 

When I worked in a BL dealership I put a new Gold Seal engine and overdrive box in an MGB and it slipped in reverse gear. That turned out to be an overdrive fault.

 

The clunk is normally in the drive shafts - are probably dried out and need some thick grease possibly in the splines. Also check condition of prop shaft and drive shaft UJ's.

 

Regards

 

Kevin

[John Morrison]

Clunck might be wire wheel splines if fitted?

 

John.

[Bobble]

Thanks for the advice so far.

 

Roger - no slip in fourth (non-overdrive) nor in any other gear. Good travel at slave as all parts are new except for one rod - I think I may have to check length of this.

 

Mark/Kevin - I agree that a new clutch is probably due as there has been no evidence of any clutch parts for the last 15 years (I have all receipts for work and parts). However, mileage has been relatively low in this period. Regarding "clunk", prop shaft and UJs are new but I'll check grease in drive shaft UJs. Thanks.

 

John - I have wires - what can be done to eliminate any clunk in splines?

 

Good stuff as usual.

 

Bob

[RogerH]

Hi Bob,

it was mentioned above about the taper pin in the clutch fork being sheared.

It is slightly difficult to be absolutely sure if it is broken but you can give this a go.

 

Disconnect the slave cy. Pull the cross shaft lever fully forward.

Very gently move the cross shaft lever reawards. When it starts to move feel if there is a slight change in the feel.

As the release bearing touches the pressure plate keep feeling if the lever carries on moving.

 

If you can sense any extra movement then the pin is sheared. If you can't feel any thing then the pin could still be sheared.

 

If you can not find any other reason for the problem then you may have the GB out.

 

How far does the end of the slave actuator rod move - is it apprx 1".

 

Also - because you have a 4A you should not have a return spring and there should be only a minimal gap/free play on the actuator rod.

It is self adjusting - but NO spring.

 

Roger

[peejay4A]

John - I have wires - what can be done to eliminate any clunk in splines?

Bob

Belting quite hard with the copper hammer works for me.

[Bobble]

OK

 

Greased the drive shafts (they seemed to be bone dry and took loads of grease) and tightened wires onto splines after replacement. Still has "clunk" on take up but am now going to ook at the diff.

 

Looks like a change of clutch is on the cards too but I have a lot of driving to do first.

 

Thanks for all the help.

 

Bob

 

PS The prop shaft and UJs are virtually new but I thought that I would grease them anyway. The nipple is squeezed between the arms of the "spider" joint and cannot be accessed with a normal grease gun. Need to find a mini version with narrow neck.

[RogerH]

Hi Bob,

you can get long (extended) grease nipples.

Put them in, grease it up then take them out and replace with the short ones to keep the muck out.

 

Roger

[Bobble]

Good thinking Roger - thanks for this.

 

You could make a full time job of this consultancy lark!

[AlanG]

I have similar sounding clunk. Having renewed all the usual culprits I to am suspecting the diff. I have just spoken to Pete Drugen who advises diffs can clunk if they have excess backlash. Before removing he suggests disconnecting the propshaft and try rotating the diff drive flange. There should only be a few thou of movement. Any more is excessive. I shall do this before getting it rebuilt.

Alan.

[Rob Salisbury]

Another source of drive take-up clunk on an IRS chassis can be the diff mounting brackets beginning to break up or the pins pulling through, best observed with the diff removed. This happened to my chassis when it was less than 7 years old, the fully boxed in repairs have lasted for the remaining 44 years and counting!!

Cheers Rob