HELP! - Primary gear Shat its self
Turbo Mini Forums

Hi all,

Could do with some help. The car suddenly got harder to get into gear so I pulled it into the garage, had some dinner and went back outside to check the clutch adjustment and there was a pool of oil under the car.

It was coming out of the clutch cover so I thought the seal had gone. I stopped the clutch and found the damage below.The top hat section is destroyed the C washer was bent out of shape.

The key washer was very tight and looked like the key section was too tight and had started to pull a little shaving off (This was a new part maybe a shit Idea.

The crank looks ok, but them what do I know...

Now I was trying to get the car to Combe for some fun, Can I just replace the primary and washers and change the oil? of is it a strip down job?

What could have caused it, clearances?

Can you buy a new primary and stick it on or does it need reaming to size?

Thanks for any help

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

photo 3 by iansongraham, on Flickr

photo 1 by iansongraham, on Flickr

photo 2 by iansongraham, on Flickr

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

photo 2 by iansongraham, on Flickr

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

These bloody photo sharing sites always changing..

It doesn't appear that you can upload an attachment to the site if your using a mac.

If you click on the pic they should grow to a decent size

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

What gear is it? 998 what? A or A+? might still have a 998 A+ one somewhere.

In my experience, the front bush clearance grows, the strain is increased on the rear bush and the front thrust washer as the gear cants over. What does the front bush clearance feel like on the crank?

If the crank running faces are good, i'd be tempted to bung another gear on there and find a decent used Original C washer, thrust face washer and the right size bronze thrust washer (might have a few of those too) to get the clearancies within tollerance.

Hi Colin, its A series 998. would be great if you have any spares

Edited by gr4h4m on 24th Aug, 2014.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

i used new new C washers when I build the engine, I should have used some used ones I think they don't seem as well made. I also used a new key washer on the flywheel.

The crank looked ok it still had some of the grease on when I put it together I will clean it off tomorrow and make sure there isn't any grooves or damage.

The gear still felt smooth on the crank, I think I caught it early.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

The top hat breaking away can quite often be from too much end float and the gear banging up against the thrust.

Thanks Graeme I'm going to look it I out it in the build book I kept on the engine. Know I did measure it, but looks like I did a shit job!

Going to see what I have lying about

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

I've got a spare 998 primary gear and can post you the crank oil seal fitting tool if you need it.

so I have cleaned it all up and looked in the spares bin, I have found another complete setup but its got a lot of wear on it and and the primary is a bit baggy on the crank.

I have found:

The original thrust washer on the setup that failed doesn't have a deep chamfer in fact about 1/2 as deep as the one in the spares bin from my old engine, I wondered if this caused issues with the end float.

The C washers and backing ring are well shot on the failed set and the parts bin set look worn so I'm going to order a new set but man they are expensive little buggers.

The key washer has a little shaving where it was tight on the crank so another new part required.

So I'm going to change the lot and check the clearance with my spare thrust washer that measured a constant thickness all of the way around and it on the higher side of the small one Minispares sell at .114".

Thanks to Andy who has offered to send out a primary. although I'm very tempted to buy a new one? I just don't want to get this far and have any more issues?

What do people aim for for the ideal end float?

Edited by gr4h4m on 25th Aug, 2014.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

use two feeler blades when measuring the end float of the primary gear, one either side at the same point as the grooves for the C washer

will do colin, I'm sure I did that lat time, but I checked my engine build book and for some reason I never put the end float down for the primary, which was strange.

I will put it all together and see what it is.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

I always try and get the clerances to the maximum. Also, the primary being a but baggy is better than being tight. The last thing you want is it nipping up, as you know.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

What's the history of the primary gear?

Looks to me as if the front bush has been damaged on installation and has simply disintegrated in use.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Paul S - I think I got the primary gear with the gearbox, which was in good condition, it had been sat a while. The gearbox had a bush to reclaim the idler face so maybe they re-bushed the primary too. it did look in good condition.

Wil_h - the other primary felt like it could be rocked on the crank. its from my old 69K engine, it used to film a bit of oil into the wok I guess it was down to this. the bearing surface looks a little worn so I was going to replace it.

I have a new one in the post and one from Andy. once its all in my hand I will try both with the new C washers and backing ring. and the non knackered thrust washer I have. I can then measure the end float and see what I have. I have ordered all Gen parts from minispares so a load of money for what they are, but I thought this was the best route.

I guess this is the difference of some newby like me putting an engine together than someone with a load of experience and skill, they can, look and measure to tell what it good and what is bad, what works and what doesn't.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

For the primary I go to the top end of the tolerances in the manual, for the bore. Yes it might be a bit baggy, and noisy and maybe even weep a little, but better that than get hot and nipping. Make sure the same tolerance is used for both bushes so it doesn't sit on the piss.
I think its less likely to expand and nip along its length so aim for nominal book tolerance as normal.

Edited by graemec on 26th Aug, 2014.

these things are never simple.. I will have to get measuring...

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

ok its all my fault...I used the wrong primary gear I must have come with the gearbox and I thought ooo this is shiny and looks in good condition I will use this one...

but it can't be a 998 one as the rear bush is much bigger than the one from my old engine. I presume that the 1275 primary is bigger at the rear?
I thought it was a bit more whiney on over run...

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

I was a total dick...

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

Yeah the 1275 primary is bigger, at least you know what happened now! Everyone cocks up sometimes, onwards and upwards!

1275 is bigger in the front to suit the stepped crank. The rear (top hat) is the same.

The front (bronze) thrust ring is obviously different too.

yep after a google it looks like I got my hands on a 1275 primary and stuck it on, what a dick...

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

Easy done and if you fitted it with the seal straight away probably hard to notice as that would support it.