Problems with 1st and reverse gears

PostPost by: Slamm78 » Sat Oct 15, 2011 9:20 pm

Having installed a completely reconditioned twin cam engine in our 1972 Sprint, and whilst we were at it, replacing the clutch, a couple of problems have started to emerge since the car has got back on the road.

Despite adjusting the clutch slave cylinder rod a number of times, when selecting 1st gear, with the clutch still down, the car judders as if it's trying to move forwards. Reverse gear really grinds when selecting unless you are really quick. We believe the clutch isn't fully disengaging, hence the juddering in 1st and grinding in reverse. The other gears select ok.

The adjuster on the slave cylinder has been adjusted to remove the slack between the slave cylinder and the fork (there is a recommended 2mm gap suggested in the Elan manual). There is now no slack in the clutch fork at all and our concern is that if we keep on going on the adjuster, then it'll might result in the thrust bearing being engaged constantly and wearing it out.

We're think we've fitted the clutch in the right way round because it just physically wouldn't fit the other way round.

Lastly, we've converted from the donuts to cv joints on the drive shafts, and initially thought the juddering in 1st and grinding in reverse might have been caused by the lack of flex in the cv joints compared to the donuts, but have concluded that's probably not the problem.

Has anyone had any similar issues/ ideas of what we should try?

Thanks in advance,
Mel
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PostPost by: Panda » Sat Oct 15, 2011 11:10 pm

Hi Mel, Certainly sounds like a clutch not releasing fully. A few things to check, is there too much free play in pedal before release lever moves, possibly due to worn master cylinder or air in system.
If the release lever seems to have full travel, the clutch plate centre may have got bent when fitting the engine, causing it to drag on the pressure plate. The release lever may have cracked and bent,therefore not pushing the release bearing fully in. All this is easily checked with the car jacked up (on stands) and with the aid of an assistant. Good luck.

cheers

Alan Pate
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PostPost by: robertverhey » Sun Oct 16, 2011 5:01 am

Maybe a problem with the spigot bush/bearing?

Only other thing I can think of apart from clutch
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PostPost by: nebogipfel » Sun Oct 16, 2011 7:51 am

Slamm78 wrote:Lastly, we've converted from the donuts to cv joints on the drive shafts, and initially thought the juddering in 1st and grinding in reverse might have been caused by the lack of flex in the cv joints compared to the donuts, but have concluded that's probably not the problem.




The driveshafts are excellent and are certainly not causing the problem.

The clutch is dragging. Why is the question?

When you press the clutch does it feel like it's doing something for the full extent of the travel or is there some soft travel on the pedal?
John

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PostPost by: AHM » Sun Oct 16, 2011 8:32 am

Put the freeplay back in to the slave cylinder/clutch fork - Otherwise the bearing will wear out as you say.

It is a new clutch - have you given it a chance to bed in?

Whilst stationary - try to select 2n'd, 3rd, and 4th gear - do you have the same symptoms?

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PostPost by: GrUmPyBoDgEr » Sun Oct 16, 2011 8:45 am

I think that the description for adjusting the required gap for the clutch release bearing is a bit misleading.
The requirement should be to have ~1mm gap between the bearing & the clutch release plate thus preventing continuous contact & the possibility damage.
Having said that I have a similar problem with my car because I blindly followed the written adjustment instructions as if it were the Bible.
When I can get under my car & have help at hand to remove & re-fit the exhaust system (for access) I will re-adjust the clutch release system with the return spring removed & just measure the 1mm as from the "end of movement" of the clutch release arm.
Hopefully this will provide the prerequisite 1mm gap, reduce free movement of the clutch pedal & eliminate gear crashing when changing gear.
The reverse gear / 1st gear problem described in the initial post is probably due to those gears not having syncromesh
Shout me down if that statement is not correct gearbox guru's :roll:
Just allowing a bit more time to engage those gears without synchro' will most likely stop the gears from "grating"

Cheers
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PostPost by: types26/36 » Sun Oct 16, 2011 9:32 am

GrUmPyBoDgEr wrote:IThe reverse gear / 1st gear problem described in the initial post is probably due to those gears not having syncromesh John


There is no syncro on reverse but the first gear has syncro.
From the description it sounds like there is a problem with the clutch even though it is new, is it the correct type or damaged, could the clips securing the release bearing have become dislodged, is the flywheel face smoth and serviceable? with the correct adjustment, the engine idleing at the correct speed and the hydralics ok it should not greate as described, I doubt some bedding in would make any real difference.
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PostPost by: Slamm78 » Sun Oct 16, 2011 9:41 am

Thanks all for your suggestions.

There some free movement on the clutch pedal. We fitted a new braided hose from the master cylinder to the slave cylinder so will re-bleed the system to check there is no air.

If the master cylinder was worn, would we be able to see anything to indicate this? Fluid leaking perhaps?

Will also try selecting 2nd, 3rd and 4th when static to see if they all judder.

We will put the slack back into the adjuster. Also, we'll remove the rubber gaiter at the bottom of the fork to inspect the condition of the fork, as my husband has just wondered if it could be bent slightly?

Will let you all know how we get on from our efforts today.

Mel
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PostPost by: AHM » Sun Oct 16, 2011 10:29 am

types26/36 wrote: I doubt some bedding in would make any real difference.


Of the friction material probably not.

A new spline, in a new position, on an old shaft, might not slide as freely as intended.

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PostPost by: Slamm78 » Sun Oct 16, 2011 12:30 pm

Upon inspection, there is blackened clutch fluid seeping into the bulkhead behind the pedal. So it looks like we need to sort out the master cylinder. The juddering happens in all gears and from what we can see, the fork looks as it should when the gaiter was taken off. The slack has been put back into the adjuster on the slave.

Hopefully, the master cylinder is the cause of the clutch not disengaging properly as we don't fancy taking the engine out again :(.

On a separate note, isn't it always the way that having done around 500 miles in the Sprint since we got it back on the road, a number of other things are coming to light that need attention!?
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PostPost by: bast0n » Sun Oct 16, 2011 5:35 pm

Slamm


On a separate note, isn't it always the way that having done around 500 miles in the Sprint since we got it back on the road, a number of other things are coming to light that need attention!?


Use them or lose them are THE watchwords for most cars - especially the Elan.

Good luck

D
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PostPost by: david.g.chapman » Tue Oct 18, 2011 6:09 pm

I second that. Even though I am not using my car much at the moment I try to give it a 10 mile blast every week.

Over winter, as a minimum, I plan to:

1. Roll the car back and forward every week to prevent flat spotting, and increase the tyre pressure to 40 psi.

2. Turn the engine over for a second or two every month - remember the water pump seal!

3. Operate the brakes and clutch every week - this prevents any water in the brake fluid corroding the bores in the hydraulic system - wiping the bores with the seals stops this apparently.

4. If rain washes the salt off the roads - get out and drive the car!

Dave Chapman.
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PostPost by: ricarbo » Tue Oct 18, 2011 7:37 pm

It could be the driven plate sticking on the gearbox input shaft, did you put a little white grease on the shaft? I think white grease is the right one, not 100% sure, someone else may know better. Or it could be a faulty driven plate, like the one on the Triumph on this site http://www.youtube.com/profile?user=Uni ... orsltd#g/u Video 158 is the one.
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PostPost by: redskatejbf » Wed Oct 19, 2011 9:06 pm

Check the length of the master cylinder push rod, from the clevis pin centre to the back of the radius that pushes the piston down the bore of the master cylinder. It should be 3.125" or 80 m/m. Until yesterday I have had the clutch `bite` very low down on the pedal for a very long time and just got use to it, reverse would normally be difficult.
The master cylinder was replaced years ago, I was going through a box of old `bits` and found the very original one, I don`t know what made me check the push rod length but I checked it and in a idle moment compared it with the fitted rod. The fitted rod was .25" shorter, I replaced it and the `bite` is now much higher and no crunching.
Its no big problem to remove the rod leaving the master cylinder in place if you are a bit of a contortionist!!!!!

Regards John.
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PostPost by: tvacc » Wed Oct 19, 2011 11:02 pm

I think I once had this problem and it was the shifter itself. The collar on the shifter had unscrewed from the top of the gearbox.

I know this is a long shot, and that you have probably checked it, but just thought I would throw it out there. Now it was like 40 years ago that his happaned, so might be thinking about it all wrong, but I seem to remember it was only 1st and reverse I had trouble with.

tony V
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