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hasuSan

GTO UN1 Fitment problem

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Anyone fitted their V8 Transmission with GTO stronger shaft upgrade?

I need help & question:

I bought the upgrade shaft from GTO engineering. The kit came with new 1st, 2nd gear and the 5th gear bearing installed in the shaft. Everything fits except one thing.

The fifth gear bearing is oversize (little bit), when I closed the transmission cover case, there is a gap and

will not sit properly. The bearing sitting in race groove is bigger. I need some advice from those

owners who upgraded their transmission shaft.

Can I heat the transmission case cover and freeze the bearing then install the cover case hoping

to decrease the tolerance?

The next solution is to machine the case bearing groove ?

Note: the original lotus 5th gear bearing has a circlip. The one came from GTO engineering, the bearing circlip

is machined (build in the bearing not a removable circlip). I noticed this is a little wider. Maybe this guide is not sitting properly in the groove?

Please help! thank you

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Hi Hasu-san,

Have you spoken to Kevin at GTO about this? I know when I bought my upgrade just recently (he fitted it so I cannot help you directly) there were several options for that bearing depending the on the particular version of the UN1 or if it had previously been modified for a different kit. He is very helpfull (has been extremely good so far) and I am sue would do his best for you.

cheers

-Chris

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Thanks Chris appreciate your help.

I tried to call him a few times but he is not around. He will be back on Monday.

Wow! you telling me the 5th gear bearing has different sizes and perhaps

he installed the wrong bearing on the shaft?

If there are several options, this is a good news. I will email him today.

Thanks

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The Lotus UN1 used two types of rear primary shaft bearing. Before 93 it was a 62mm dual ball, after 93 it was a 52mm dual taper.

The GTO upgrade works with the existing 62mm bearing but if you have a 52mm bearing (which with a V8, I assume you do, unless your casing has already been machined for some reason) Kevin supplies a new bespoke bearing for the upgrade to fit your casing.

I spoke to Kevin on Monday so he is around, but at the time of year he is away quite a lot at race meetings. Next time you speak to him, ask for his mobile number.


May: DON'T hit it with a hammer!

Clarkson: Why?

May: Cause it's the tool of a pikey.

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Thanks Neal:

At one time, I had his cell # but I lost it. I will see if I can ask his cell, sometimes people don't give their cell #.

I will measure the original bearing if 62mm or 52mm, then I will measure what he installed in the shaft.

Neal by the way, do you happen to know the bearing brand and part # of the 62mm and 52mm?

Worse to worse I might be able to cross reference here in the US.

OK...I measured the original Lotus bearing and you are correct 52mm.

I measured what GTO gave me and its 52.04mm

so where do I go from here?

Neal said: Kevin supplies a new bespoke bearing for the upgrade to fit your casing.

What bespoke bearing means?

Edited by HASUsan

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From what I understand the problem with the standard 52mm bearing is that the inside diameter is too small to fit the fatter upgraded primary shaft. I don't know whether Kevin then uses a different 52mm bearing with a larger inside diameter, or if he machines out the standard one.

I'm sure when you talk to Kevin he can sort out, from my experience he's a very nice guy and easy to deal with. As you say it could just be a problem with aligning the groove on the bearing to the case.


May: DON'T hit it with a hammer!

Clarkson: Why?

May: Cause it's the tool of a pikey.

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Have a look on the concurrent GTO contact thread there is a link to there new website and look at the UN1 upgrade page - there is a mention about he need for diff size bearing.

I found Kevin very helpfull and a spot on guy when I dealt with him I'd expect all to become clear when you get hold of him.

Jeff

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Just in case you encounter the same problem:

The solution? I took the bearing to local machine shop and reduced it a little bit.

The upgrade transmission is now back in order.

Thanks for the help!

Edited by HASUsan

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