Gearchange problems

[Tom Fremont]

Word is one failure mode for the clutch pressure plate is decreased retraction for a given length of push. 

I re-used a SACHS PP after 56,000 miles ( gearbox swap due to O/D failing to engage ) because a new one was out of stock and didn't want to wait. I'm gentle on clutches so reckoned it would last for a long time yet. Driven plate was renewed, LUK type which had loosened in its splined hub, imminent failure. Replacement was PowerStroke from Taiwan as this is what TRF's Magic Clutch kit gets today.

So what ensued was difficulty engaging 1st gear unless rolling. Finally, reverse would not engage without dragging teeth. I then replaced the M/C with a Girling I had on hand and replaced the clevis and pin which had only 13,000 miles post gearbox swap and new TRW M/C. There was a good 1/8" slop in that joint, translating to 3/16" at the throwout bearing. It's improved but still fights more than it should. As I'm hoping to pull the engine for a complete re-spray late this year I'll live with it I suppose.

I would replace the clutch PP in this case.

[John L]

There are few things I would do here,

Add some new cross shaft bushes, to take out the wear on the cross shaft, there are some that are much longer, and so run on an unused part of the shaft, or use 4 of the std bushes.

The pins in the fork don't look too good replace those,

I would drill a hole in the nose at the gearbox end, underneath, to let any oil that may come from the gearbox seal, come out there,  rather than going to the end of the nose and coming out on the fingers and clutch plate.

Make sure the flywheel spigot bush is a good fit on the input shaft, and not worn out, and make sure you use the dowel bolts in the right places when reattaching the gearbox.

The slave cylinder should be mounted on the rear of the slave plate, and plate attached to the front of the engine plate.

If you do take off the nose, rotate the circlip on the bearing so that the open part is allowing oil to the drain hole on the left side, when looking at the gearbox.

[PLTR6]

2 hours ago, ntc said:

For starters the forks are not central remove nose cone and check it’s flat to the gearbox secondly check the sleeves in the bell housing are they worn?

Hi, good point,  yes the photo does make it look off centre but I just checked with dividers and the forks are central.  There isn't any wear on the splines or the cone on the bell housing.

[PLTR6]

2 hours ago, ntc said:

For starters the forks are not central remove nose cone and check it’s flat to the gearbox secondly check the sleeves in the bell housing are they worn?

Hi, good point,  yes the photo does make it look off centre but I just checked with dividers and the forks are central.  There isn't any wear on the splines or the cone on the bell housing.

[John McCormack]

Sorry, misread the post so deleted my comments.

Edited May 2, 2023 by John McCormack

[astontr6]

On 7/16/2022 at 12:17 PM, PLTR6 said:

Hi, I’d appreciate some advice on my 1970 TR6 clutch problems..........

I rebuilt my TR6 over lockdown. ‘New’ chassis and body, swapping the engine and box over from one chassis to the other without doing anything major to them because they were working perfectly, and they have been undisturbed for at least 24 years with fairly limited mileage.

My first big drive was to Malvern last year when I found getting into 2nd gear difficult, especially going down from 3rd .

Since then it has been getting progressively worse, to the point where it is no fun driving it. I’ve tried a few fixes but no joy.  The symptoms are:

·        Engine off I can get all the gears. Not Ford smooth, but doable.

·        Starting from cold, gears are gettable, but reverse grinds horribly.

·        As the car warms up it becomes harder and harder to find all gears, especially 1st and 2nd and reverse but then I get nasty grinding on 3rd.  Double declutching and slowing the engine revs can help, but not always.

·        Eventually I have to force it into 1st or 2nd to get going, and that isn’t easy. One day I really will get stuck at a junction. Quite stressful.

·        If I am stationary and get it into gear there is no creeping forward or change in revs.

·        Driving along there is no clutch slippage.

·        Overdrive works fine

 

What have I looked at so far?

·        I have bled and bled the clutch, including holding the bleed valve vertical as in other posts.

·        I have taken the slack out of the linkage, so there is minimal slop at the pedals and the clutch cylinder. The pedal box has new bushes.

·        I’ve measured the movement in the rod at the slave cylinder, 17mm which seems ok according to the forums.

·        I disconnected that rod and checked for ‘slop’ and it feels pretty tight, hanging vertically.

·        I’ve topped up the gearbox with oil....there is a slight leak but not that much.

·        When I rebuilt the car I refurbed the master cylinder with new seals.  It is a .70” version.

 

What next?

I really want to exhaust all possibilities before I take the plunge and take the gearbox out.  I am aware of weaknesses inside the clutch, especially the fork pin, and maybe the synchromesh is the problem?.  If the forum’s advice points there, so be it, but this is one last try to avoid it!  Thanks in advance.....

I personally do not like the .70 version it gave me trouble with gear selection as I believe that clutch disengagement is very marginal with that size of M/C and I changed it for the .75 but I also removed all the wear in the clevis pin holes as they were oval with plenty of slop. Having done all that, I then had no more trouble with gear selection and that was 35 years ago!

Bruce.

[super6al]

Bruce has a good point there. Looking at your first post, overhauling the M/C was about the only thing that could have effected a change to a previously good gear change. Given nothing else is obvious I would be tempted to go back to that as a starting point.

Alan 

[ntc]

The movement on the slave illuminates that 

[PLTR6]

Hi, Thanks for the continuing input, much appreciated. 

I get the point on the Master cylinder, and yes I was hoping the fact that I got plenty of movement at the slave indicated that part was OK, but if I'm still suffering after I get it back together then yes I will relook at the hydraulics.

For now, I need to choose a clutch.  The most common one from the big suppliers is Borg & Beck (can't afford Laycock!) so I'm about to press the button on their kit HK9665......unless there are any great ideas out there!

Thanks again. 

[Rob Salisbury]

Here's a thought, after 20 years the synchro cones may well be reaching the end of their lives, and the box full of new GB40 is proving just too slippery for them to grab and hold the gears as they should, creating the baulking and grinding.       What did the oil that came out look like, were there fine particles of brass suspended in the oil?

Cheers Rob

[Mike C]

3 hours ago, Rob Salisbury said:

Here's a thought, after 20 years the synchro cones may well be reaching the end of their lives, and the box full of new GB40 is proving just too slippery for them to grab and hold the gears as they should, creating the baulking and grinding.       What did the oil that came out look like, were there fine particles of brass suspended in the oil?

Cheers Rob

GL5 , or other too slippery oil will give the symptoms noted in the forward gears but not in reverse.

[PLTR6]

11 hours ago, Rob Salisbury said:

Here's a thought, after 20 years the synchro cones may well be reaching the end of their lives, and the box full of new GB40 is proving just too slippery for them to grab and hold the gears as they should, creating the baulking and grinding.       What did the oil that came out look like, were there fine particles of brass suspended in the oil?

Cheers Rob

Hi Rob,

The oil that came out was filthy.....the filler plug was so rounded off and so stuck I doubt it the oil was changed when serviced over  the years.  I didn't notice any brass particles, but there were iron filings on the magnetic drain plug, not a surprise after the recent noises.

I'd really rather not start messing with the gearbox itself just yet.  Now it is out of the car I can engage all 4 plus reverse quite easily.....I'm hoping that is a good sign, pointing to the clutch system as the focus......but then again I had thought it was the fork pin and I was wrong there!

Thanks

Paul

[Rob Salisbury]

Hi Paul,

                Hmm, gearbox oil shouldn't be really filthy, doesn't get burnt carbon like engine oil, .......... but back to the clutch system, have you checked the flexible supply pipe to the slave cylinder, these sometimes become soft and expand as you push down the clutch pedal and so reduce the movement of the slave, especially as the engine warms up.

Cheers Rob 

[PodOne]

No expert Paul.

What's the milage?

Manky oil may now in fact be a metal grinding paste with metal fillings on the plug would suggest appreciable wear. Is it not worth having the box at least inspected while it's out given the amount of work involved taking it back out again if the issues remain?

Andy 

[PLTR6]

12 hours ago, PodOne said:

No expert Paul.

What's the milage?

Manky oil may now in fact be a metal grinding paste with metal fillings on the plug would suggest appreciable wear. Is it not worth having the box at least inspected while it's out given the amount of work involved taking it back out again if the issues remain?

Andy 

Thanks Andy,

70K on the clock, and its had a gentle last 25 years.  An inspection would be sensible, any thoughts on a good expert?   Still, I can't get past the fact it was working fine until I switched chassis.  The iron on the magnet was very fine, maybe not too bad for 30 years if my suspicions about no changes are true.

Paul

 

[astontr6]

On 5/3/2023 at 5:41 PM, PLTR6 said:

Hi, Thanks for the continuing input, much appreciated. 

I get the point on the Master cylinder, and yes I was hoping the fact that I got plenty of movement at the slave indicated that part was OK, but if I'm still suffering after I get it back together then yes I will relook at the hydraulics.

For now, I need to choose a clutch.  The most common one from the big suppliers is Borg & Beck (can't afford Laycock!) so I'm about to press the button on their kit HK9665......unless there are any great ideas out there!

Thanks again. 

The only point to remember is that when you buy a B & G clutch it is not made by Borg & Beck but a copy as Firstline have bought the trade name. If you do buy one count the rivets on the friction plate and make sure there are 16 and not 8. The friction material on the 8 ones had a habit of falling off as I had personal experience of this problem. Then you will have a gear change problem?

Bruce.

[PodOne]

10 hours ago, PLTR6 said:

Thanks Andy,

70K on the clock, and its had a gentle last 25 years.  An inspection would be sensible, any thoughts on a good expert?   Still, I can't get past the fact it was working fine until I switched chassis.  The iron on the magnet was very fine, maybe not too bad for 30 years if my suspicions about no changes are true.

Paul

 

Hi Paul

Plenty of folk go here https://petecoxsportscars.co.uk and have had great service.

Andy

[PLTR6]

Update on my clutch problems......

New B&B clutch fitted, taper pin fine, cross bolt fitted anyway for future backup, alignment dowels in place, bushes fine, all reassembled and bled again. What a job that was.

First drive was initially fantastic. Into reverse smoothly, then nicely up through the gears and into overdrive.  I dared to hope.  Then approaching a corner I just could not go from 3rd to 2nd until the engine slowed right down, and then it was a struggle.  It has carried on like that, occasionally slotting in nicely, but generally so near but so far. 

So now I am looking again at the hydraulics.  Still can't find any slop, and still getting 16mm of slave rod travel, but I did notice something odd:  The slave rod looks long, having obviously been modded by a distant previous owner, measuring 6.25" from clevis pin hole to tip. The standard seems to be 6".  Could this be a factor, even though it has been fine for 25 years?

Picture below, and yes the master is mounted on the gearbox side of the plate.

All thoughts welcomed, I will continue to delve!

[Rogcastle]

Hi Paul

From your description of when you changed down a gear to second, it sounds very similar to when you try to change gear without using your clutch. The gear will pop in when the engine revs match the gearbox gear. This would I guess point to a problem with your hydraulics not operating your clutch. Slave cylinder/Master cylinder or plastic pipe. Bearing in mind the amount of effort you have put in so far I would replace the lot.

Best of luck

Roger

[G_Cam]

HI
I hope you do not mind me resurrecting your thread.
I'm Just wondering if you ever managed to find the root cause?
I am experiencing very similar issues and I'm going through almost identical fault finding at the moment.
Having convinced myself that the cross shaft pin had seared I have removed the box (That is a joy..LOL). However, it all looks fine. I'm just about to replace the clutch (like you I am struggling to select the best 'modern' option?

Thanks

Graham

[John L]

Looking at the picture of the clutch cover, the spline on the clutch plate doesn't look very central, I think you should take the clutch plate out, and check for oil on the plate and when spun on the input shaft that it runs true, the plate may have been bent when last fitted.  Check also the spigot bush size, compared to the input shaft.

John

[PLTR6]

On 10/23/2023 at 1:29 PM, John L said:

Looking at the picture of the clutch cover, the spline on the clutch plate doesn't look very central, I think you should take the clutch plate out, and check for oil on the plate and when spun on the input shaft that it runs true, the plate may have been bent when last fitted.  Check also the spigot bush size, compared to the input shaft.

John

Hi John, Thanks for the comment.  I think it is the camera angle rather than the clutch alignment.....I used the proper tool and made very sure all was aligned when I assembled it.  It is now a new clutch, replaced in an effort to fix this problem. There was no oil on the old clutch.  Please keep the ideas coming, I'm still struggling! pne question.....I have now filmed and measured the clutch slave rod movement.  It is 15mm..........some forum posts say this is lenty, some say it needs 16mm.  Could 1mm make that difference?    Cheers, Paul

[PLTR6]

On 10/22/2023 at 11:57 AM, G_Cam said:

HI
I hope you do not mind me resurrecting your thread.
I'm Just wondering if you ever managed to find the root cause?
I am experiencing very similar issues and I'm going through almost identical fault finding at the moment.
Having convinced myself that the cross shaft pin had seared I have removed the box (That is a joy..LOL). However, it all looks fine. I'm just about to replace the clutch (like you I am struggling to select the best 'modern' option?

Thanks

Graham

Hi Graham,

Welcome to the club.  I'm still struggling.  I can go up the gears nicely, 4th to 3rd is fine, but 3rd to 2nd (ie approaching a corner!) is often impossible.  Things I have done/tried:

New clutch and pressure plate (Borg/Beck)

New Slave and Master cylinders.

Checked correct rod length for both cylinders

Cross drilled the clutch fork

Make sure you have the alignment dowels fitted when refitting the gearbox

Tried the top of the three holes in the clutch actuating lever (more travel)

Refurbed the pedal box, new bushes etc

Took all the slop out of the linkages, inc a bush in the pedal to clutch master link.

Bled, and Bled, and Bled again. Manual and Ezi bleed.

Checked gearbox oil levels.

Filmed slave rod travel (15mm, should be enough but some do say 16mm)

I'm sure there is more.

Next on the list:

I may remove the gearbox selector mechanism.  Maybe something was dislodged, but not sure how I will tell.

Look at an adjustable master cylinder rod, to get a bit more travel.

One day I will admit defeat and take it to an expert, but I really don't want to mess with a gearbox that was fine until the chassis swap.

 

Hope this helps, please let me know if you have any joy.

 

Cheers

 

Paul

 

 

[PodOne]

32 minutes ago, PLTR6 said:

Hi John, Thanks for the comment.  I think it is the camera angle rather than the clutch alignment.....I used the proper tool and made very sure all was aligned when I assembled it.  It is now a new clutch, replaced in an effort to fix this problem. There was no oil on the old clutch.  Please keep the ideas coming, I'm still struggling! pne question.....I have now filmed and measured the clutch slave rod movement.  It is 15mm..........some forum posts say this is lenty, some say it needs 16mm.  Could 1mm make that difference?    Cheers, Paul

Having done the exact test for static poor gear selection I had IIRC 12mm prior to a re bleed and 16-17mm which resolved the issue completely. Can’t see 1mm making a difference and I guess you will have checked there is no slop at the clutch pedal to MC? If there is it will be costing you a few more mm which might be the difference to getting it to go into gear.

should have read your next post! Seems to me you have nailed everything and it’s expert inspection time! That’s unless someone has some other ideas to try.

Interested to hear what the eventual outcome is. Best of luck and keep us all posted.

Andy

Edited October 25, 2023 by PodOne

[Kevo_6]

I would drain the gearbox and strain the oil and see if anything is in it. I had a similar problem and it was the lay shaft and bearings gone. Good luck.