Best gearbox for XU9J4

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ttocsc
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1988 BX 16 RS Pilot with XU9J4 D6C swap, fast road inlet cam
2004 BMW E46 318ti
2006 Volvo V70 2.4

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2002 MG ZR 105 - RIP SP02 OAJ
1985 BMW E28 520i - RIP C759 WKS
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Best gearbox for XU9J4

Post by ttocsc » Mon Sep 24, 2018 2:01 pm

Hi everyone, I'm new here as I've just inherited the ultimate Q-car, a slightly rusty and faded 1988 BX 16 Pilot with a running, freshly rebuilt XU9J4 swap. It runs perfectly but synchromesh on 3rd and 4th is completely broken, which makes it almost undriveable.

Have a few other XU gearboxes sitting around, got 1.9 XUD turbo and non-turbo boxes, one from a BX 1.7 TZD and one from an 8V GTi, although it's in need of refurbishment too. Which ratios suit the valver engine best?

Kaapelimies
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Re: Best gearbox for XU9J4

Post by Kaapelimies » Mon Sep 24, 2018 3:52 pm

So what do you want? Short box for quick acceleration (and a lot of shifting to do) for cornering, or a long one for relaxed driving?
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Kitch
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Re: Best gearbox for XU9J4

Post by Kitch » Mon Sep 24, 2018 5:22 pm

Of all those, the 8v GTi, though the 16v box is much better. I'd fix the box, personally. The ratios keep the engine in the power band when driven hard.

ttocsc
New Member
Posts: 3
Joined: Mon Sep 24, 2018 1:51 pm
Location: Perth
My Cars: Current:

1988 BX 16 RS Pilot with XU9J4 D6C swap, fast road inlet cam
2004 BMW E46 318ti
2006 Volvo V70 2.4

Past:
2002 MG ZR 105 - RIP SP02 OAJ
1985 BMW E28 520i - RIP C759 WKS
1998 Volvo V70 2.5D - RIP V704 DGH

Re: Best gearbox for XU9J4

Post by ttocsc » Mon Sep 24, 2018 5:55 pm

Kaapelimies wrote:
Mon Sep 24, 2018 3:52 pm
So what do you want? Short box for quick acceleration (and a lot of shifting to do) for cornering, or a long one for relaxed driving?


Long one preferably, I'm coming from a completely gutless N/A Volvo so the Mi16 lump feels torquey to me. Feel 5th is too short as standard on these cars, the drone at 4100rpm at 75mph gets grating hahaha

ttocsc
New Member
Posts: 3
Joined: Mon Sep 24, 2018 1:51 pm
Location: Perth
My Cars: Current:

1988 BX 16 RS Pilot with XU9J4 D6C swap, fast road inlet cam
2004 BMW E46 318ti
2006 Volvo V70 2.4

Past:
2002 MG ZR 105 - RIP SP02 OAJ
1985 BMW E28 520i - RIP C759 WKS
1998 Volvo V70 2.5D - RIP V704 DGH

Re: Best gearbox for XU9J4

Post by ttocsc » Mon Sep 24, 2018 5:57 pm

Kitch wrote:
Mon Sep 24, 2018 5:22 pm
Of all those, the 8v GTi, though the 16v box is much better. I'd fix the box, personally. The ratios keep the engine in the power band when driven hard.


Suspect it's in need of major overhaul - finding gears is like trying to use a gearstick to draw an imaginary H in a bowl of soup, and that's with the linkage bushes all replaced. Crunches like a bugger into 1st and reverse too, even with a brand new clutch. Might as well spend the money now, rather than cheaping out I suppose

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Jaba
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Re: Best gearbox for XU9J4

Post by Jaba » Mon Sep 24, 2018 6:00 pm

If the syncro on the gears themselves are not worn then why not just use the synchroniser from another box. As far as I know it is the same part.

Alternatively if its all shot then the 16v uses the same 3rd and 4th gear ratios,25/32 and 32/31, as the 19d and some other models too ( but with different diff ratios) so you could cannibalise 2 boxes to get a decent working box.

And while you are at it some people fit the 5th gear from a TD box to drop the revs and noise in 5 gear
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Kitch
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Re: Best gearbox for XU9J4

Post by Kitch » Tue Sep 25, 2018 9:32 am

As above ^^

Some people use the 16v gearbox, only with 5th gear from a TD fitted. Lowers the revs by about 500rpm in top, I believe. It's not something I'd do, as I like the originality and performance of the original setup, but then I don't use my car much. If I was on the motorway every day, I'd probably have done the same thing.