SRi 20seh gearbox problem

[Joner1983]

I put my Cavalier SRi in for a new clutch this week but they are now telling me the new one won't go in as there's a problem with the gearbox. It's going to mean having to send my gearbox away to be dismantled and repaired at a cost of about £1300 I have suggested to them that I'll source a replacement box instead but there's no F16 boxes available near me. I'm wondering if an F18cr or F20 box is a straight swap and if so will it affect my performance?

Cheers in advance

[Robsey]

An F20 was an option at that time, but both F20 and F18 will "fit".
The F18 does not have the little hatch at the bottom of the bell-housing, so always requires a box-off job to work on the clutch.

In their day, the F16 and F20 could be done with the box still attached.

Preference would be down to gear ratios...
There are many options around with close and wide ratios for each version.

[Joner1983]

Thanks Robsey

That's great that I've got a few options if I can't get another F16. Didn't realise there were different ratios on the F20, I'll have to look into what's available as I was quite fond of the low torque on my SRi before the clutch went. Can I assume the F16 on an SRi is close ratio?

[Robsey]

Yes - I would expect so...
The thought being those high revving quick standing starts that you would expect from a "sport" variant.

Wide ratios are commonly found on the company rep mobiles - used for munching motorway miles.

[vexorg]

I cant really see why the gearbox wont go on and it'll need a £1300, do they have the right clutch plate?

[Robsey]

I know there are two types of clutch assembly.

An early one for the flat flywheel,

And a later one (October 1992 onwards) for the recessed "pot" flywheel.
The same as used on Calibras.

I did wonder why they couldn't get a clutch to fit one of the commonest gear boxes.

Did they fit the wrong kit?

[Joner1983]

I can't remember exactly what he said and I'm not too clued up on gearboxes but I think he said something about not being able to get a shaft back in place. They had previously bought the wrong clutch which I presume was a later one but they assure me they now have the correct one. I'm starting to think I bought a dog

[Robsey]

I presume he means the output shaft.
They can be very stiff on 5 speed boxes,
But... if the shaft came out, then it should go back in.

But - I wonder if it is the garage rather than the box at fault.

I fitted a few boxes and clutches in my early twenties (F10s and F13s), when I was still learning the basics of mechanics. But I do not recall any problems with any of those jobs.
(I am not a trained mechanic - I was a bench fitter back then).

[ilovedmymantas]

It does sound a bit suspect. How much do you trust this garage?

I'd get a second opinion if possible. Oh! That's what the forum is

I trusted one for three years until they wanted to change the engine because they weren't willing or able to find the cause, it was noisy and rattly although performance didn't seem to be affected.
- It cured itself two weeks later after I removed some oil after the service. I reckon foaming.

Back to the gearbox....

If you do have to change, which I doubt, here's a table of the ratios. I can't find the source, it was several years ago and I just saved the image



I've noticed the F16cr is the same ratio as the F20cr, why

[vexorg]

There are different final drive ratios on them too, the diff gear ratio

Code: Select all

Gearbox   1st   2nd   3rd   4th   5th   6th   rev   FDR
========================================================
F10/F13   3.55  1.96  1.30  0.89  0.71        3.31  4.18
F16w      3.55  1.95  1.28  0.89  0.71        3.33  3.94
F16c      3.55  2.16  1.48  1.13  0.89        3.33  3.55
F18w      3.58  1.87  1.23  0.92  0.74        3.33  3.55
F18c      3.58  2.14  1.48  1.12  0.89        3.33  3.55
F20(3.55) 3.55  2.16  1.48  1.13  0.89        3.33  3.55
F20(3.72) 3.55  2.16  1.48  1.13  0.89        3.33  3.72
F23       3.58  2.02  1.35  0.98  0.81        3.31  3.84
F25       3.38  1.76  1.12  0.89  0.77        3.17  3.82
F28       3.57  2.16  1.45  1.10  0.89  0.74  3.32  3.72

[vexorg]

The biggest problem is usually aligning the clutch, but I'd hope a garage would have all the tools. It can be off by half a mm and it just wont go in. Or can be lined up and if the gearbox isn't perfectly straight going on then it'll not go or move the friction plate.

It's a horroble job if it doesn't go first time, gearboxes are really heavy and need a bit of manhandling to go on. You run ot of strength quickly.
The F28 is about 53kg, the rest are somewhat lighter.

[Robsey]

The joy of the F10, F16 and F20, is that they can all be done without splitting off the box.

In the past, what I have done with a shaft that did not want to go back in, was to jack up one of the front corners and spin the road wheel until the splines lined up within the flywheel on the box.
As soon as the splines lined up - the shaft would slide back home.

It has worked every time... on an old F10w, my existing F18w during an engine swap and even a mk1 Fiat Punto 1.2 16v Fire.

Just for info -
The F10 and F13 would not fit your car as they are for the small Family 1 engines - they use a smaller diameter output shaft.

I also read somewhere that the number after the F is the torque or force that the engine is rated at.

Something like...
F16 should be 160 lb/ft,
F20 = 200 lb/ft and so on.
But don't quote me on that, or the stated units.
Bigger the number, the more torque or axial force the box can handle.

[Joner1983]

I've got no reason to doubt them as I've been using them for quite a few years. Admittedly none of my other Cavs in the past (8 of them) ever needed any serious work. I'm led to believe one of their guys knows his stuff when it comes to Cavs as he was trained at Vauxhall in the 90s and knows them very well. Unfortunately I don't know enough about transmission to question them really so a replacement box is my best option at the moment.

I've come across an F16cr on ebay but it's 300 miles from me (I live in Swindon) and was on a Nova with a 2.0l conversion so I can only assume it's been ragged

[chrisp]

Like others I'm struggling to see why a new gearbox is suddenly required because of difficulties with clutch replacement. If the gearbox was working OK before the clutch job was started it should still be OK now.
I think you need to find out whether the garage has removed the gearbox to replace the clutch, or has made use of the facility to withdraw the input shaft to the gearbox into the LH wheel arch space so that the clutch can be unbolted and removed through the hatch in the bottom of the bell housing.
If the latter, I'll bet that the input shaft won't go back through the new clutch plate because the splines haven't lined up, and the previous post about spinning a front wheel until they do line up should fix the problem.
If the former, and the garage has removed the gearbox, I think you should ask to see it and for them to explain what is wrong with it that is preventing it being re-installed.

[chrisp]

On further reflection, perhaps the garage is saying that, whatever the transmission fault was that caused you to seek a clutch renewal, it wasn't in fact the clutch at fault but was instead a gearbox fault - and that's why the gearbox needs repair or replacement.

[Joner1983]

I think I might have to go in there and put a few of these points to them especially if it's something as simple as the splines not lining up.

I'm pretty sure they are using the window as originally they had the wrong clutch kit and they said they'd have to remove the box to fit it if they couldn't get the correct one.

They did mention the shaft was unusually difficult to get out. It had been off the road for 19 years before I got it back on the road this year, is it possible it got seized in there and they broke something getting it out?

[chrisp]

If they mentioned that the input shaft was difficult to get out then they definitely were using the access hatch method to remove & replace the clutch. And yes, if they had to be a bit brutal to move the shaft (using a slide hammer attached to the end of the shaft?) then I guess they might have broken something within the gearbox. But how would they know that this had happened? Maybe they can't get the shaft to go back into place and have just assumed something is broken within the gearbox, when it may just be the splines are not lined up.
If they did break something in the gearbox it is at least arguable that they should contribute towards putting it right. Before getting brutal they ought to have contacted you, said that the shaft is proving difficult to move and ask you whether you were happy for them to apply force, at the same time warning you of the possible consequences. Then you could instead have authorised them to remove the gearbox to get at the clutch. More labour hours to do it this way of course, but cheaper then replacing a damaged gearbox.

[Joner1983]

Anyone got any idea what gearbox is in a 1993 facelift Cavalier SRi 8v (c20ne engine I think) a guy is breaking one but doesn't know what box it has. I think he's a Ford bloke
I always assumed all the facelift SRIs had F18CR but I've heard one or 2 people say the facelift 8v had F16CR???

[vexorg]

I thought the F18 came about later, around the ecotec time.

I'll probably fit, though clutch changes will be more expense in future (that reads funny given the context!!)
You'd need to check the drive shafts are the same.

[Robsey]

The F18 -usually in wide ratio format were introduced to the Cavalier range on the "R" model year, 1994.

As for C20NE equipped SRi's.....
I would need the VIN or reg number to see what it left the factory with.

I suspect most close ratio boxes would have been -
F16CR for all model years
or
F20CR for models upto "P" model year 1993.

If it is an F18, it will not have an inspection hatch for the clutch.

The gearbox "F" code is cast onto the top of the box, in huge letters next to the gear selector turret.

[Joner1983]

Luckily I've managed to source an F20 from a guy breaking a Calibra redtop down in Dorset so I've dropped the box over at the garage so it's over to them now. Fingers crossed there won't be any issues and I can have my SRi back.

When I get my 'faulty' F16 back I'm tempted to open it up and have a look. Is it a complicated thing to do?

[vexorg]

If you've never opened a gearbox befoer then it's unlikely you'll know what to look for, just a mass of shafts and cogs.

[Joner1983]

Fair enough, probably best to flog it for spares or repair and recoup a few quid then

[Envoy CDX]

I cant really see why the gearbox wont go on and it'll need a £1300, do they have the right clutch plate?

Good questions really, they may have the later Cav clutch (or something similar). F18 boxes used a different flywheel, so therefore would have had a different clutch and pressure plate.

On an f16 box, there is no need to take the gearbox off, just the endplate on the box, and you can pull the input shaft back from there.

[Joner1983]

Finally got my SRi back complete with replacement gearbox and clutch. Seems to be fine now apart from my eml keeps coming on and off as I'm driving and the occasional stutter on acceleration