Making the right selection

[breskit]

Ok, I took my gearbox off this weekend in an effort to try and work out why it's been so difficult changing gear. The loud crunching sounds that were eminating from the gearbox suggested that something in the clutch area was not working.

Having read some earlier posts here about the length of pivot pins, I wanted to eliminate this as the first problem. So up the car went, undo all the nuts and bolts and hey presto, one (heavy) gearbox removed.
Checked the length of pivot pin - 43mm. That should be OK, but I put a couple of washers behind it just to make sure. Reassemble everything and try again. Clutch not disengaing so adjust brackets and things. Clutch now OK. Engine starts in gear under no load.

The problem that now remains is that trying to find 1st, 2nd, 3rd, etc...with the engine running is almost impossible most times. When the engine is off, the selection is much easier although quite notchy.

Any ideas? I though that perhaps it may be the remote selector, although there doesn't seem to be much to it (thanks Mr Haynes). Could it be the gearbox itself? I'm hoping not.....

Help, as ever, much appreciated.

Tony B

http://homepage.ntlworld.com/tony.breski

[wilf]

Tony, assuming that your clutch is indeed now disengaging properly, there could be several reasons for your problem, I can think of:

1/ Synchro badly worn in your box (unlikely to show up on more than one gear unless it's totally worn out)
2/ Bent or worn selector forks
3/ Grade of oil in the box incorrect
4/ Incorrect alignment of bellhousing to block
5/ Severe wear in the selector assembly
6/ A long shot - wear in the input shaft main bearing? Not sure if this would show up the symptoms you describe


Only one of the above is a quick fix (oil), let's see if anyone else can come up with any other quick checks to make.

Does the problem go away or get worse once the 'box is warmed through? Could you see any "lost motion" in the selector assembly - i.e. can you move the stick without corresponding motion of the selector rods?

HTH

Wilf

[robert]

Are the dowls still in the block, to line up the bellhousing. If not you will have to dial it back in, but that means an engine out. x(

Were the load crunching sounds like when you try and change gear without a clutch or just a general crunch as the gear is engaged?

Robert
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[breskit]

Some responses:

Oil - I'm now using ATF fluid. Initially I had put some gear oil in but it was suggested here before that I change this, so I did.

Bellhousing. As Rob suggests there are dowels on the bell housing that help align the box to the engine, so that eliminates that problem.

I've not really tried with a warm box (oo-er) as I normally just want to drive the thing in/out the garage, so things are probably cold. What should happen when it's warmed up, easier selection? Better lubrication of gear, etc?

Thanks,
Tony B

[robert]

Oil tends to be very viscous when cold, by warming the oil, it aids the binding process to the moving elements within an engine or gearbox, and reduces friction.

As an example, a rolling road test in the morning with cold oil will cause a drop of around 40hp from flywheel to rear wheels, when warm, the drop is about 15hp due to less friction and the ability of the oil to coat the surfaces.

Robert
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[robert]

A good article of oil properties can be found at http://www.totalkitcar.com/tech_talk.htm

Robert
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[Dan]

Tony,


Is the box your using the same age as the engine? Is it an LT77 or R380. The above list from that Wise 'young' Wilf doesn't bode well. I opted for a new R380 box from RPI - total cost £970 but hopefully I won't need to take it out for repairs for years . Hope you find a cheaper solution to your problem...


Dan 'Were all these nuts used before' Man
www.cobra.kitcar.btinternet.co.uk

[wilf]

Tony B - been thinking some more (even tho' it hurts) - are the engine/box/bellhousing all from the same car? What I am trying to say is that even though you may have alignment dowels in there between the block and the bellhousing, if the whole assembly was not originally "together", you could still have an alignment problem.

ALso, how sure are you that the clutch is clearing properly - if you jack the car up ( and use axle stands of course), put it in gear, have an assiatant depress the clutch, can you turn the propshaft easily or ois there any drag? As the assistant slowly releases the clutch, can you feel the "bite" point as you turn the propshaft?
You will have to turn the propshaft, not a rear wheel, since I assume you have an "open" diff???

I am still trying to think of "cheap" fixes - it could be you still have clutch drag. One other way to determine this is whether the thing will go into reverse with engine running and car at standstill. If it always crunches, you still have clutch drag. Remember to give the 'box internals a little time between depressing the clutch and trying to engage reverse - otherwise you could get a false impression due to the momentum of the box internals keeping them spinning for a short while, even after the clutch clears.

HTH

Wi
Wilf

[breskit]

Thanks guys. I'm also looking for cheap fixes and think that you are on the right lines that I still have clutch drag.

I spoke to a guy called Ian at the Runcord SD1 Centre (great bloke, knows a lot about SD1 & Rover engines in general) and he talked me through a number of options. With me thinking that it could be the gear selector at first Ian pointed out that as there was very little inside this, it is highly unlikely to be the problem. The gearboxes themselves are failry heavy duty are rarely go wrong, so this left one consideration that the clutch was still engaged when I'm trying to find gear. This must be the case as I can find the gears easily enough when the engine is off.

After speaking to Ian, and recalling what Dan 'we're all nuts' Mann had said about the pedal adjuster, it got me thinking. Dan said that his adjuster was set around half way. Mine is set more towards the top. I think (and hope) that by making the required adjustment, this will fix the problem. I'll try this tonight and let you know.

Thanks again,
Tony B

[kev]

Easy way to check for clutch drag, put it in first gear, brakes off, clutch pressed to the floor,clear road in front!!! , now try to start the engine, if the car tries to move then you've clutch drag, if the clutch is dragging a little then the engine should start but the car should stay still (ish), check to see how much pedal movement you've got before full bite with the engine running. The clutch shoouldn't bite until you've got a noticeable movement in the pedal in my opinion at least a quarter of the pedal movement. It should be fully bit long before the clutch pedal is at the top.

regards
Kev