# What's best? 02A or 02J for Mk3 1.8t swap



## coons88 (Aug 20, 2008)

I'm mid project for a Mk3 1.8t swap. I have 2 gear boxes, an 02A from a Mk3 GTI 16v, and an 02J from a Mk4 GTI 1.8t.

The 02J would be the strongest, I know that. But in terms of ratios, any opinions on what would be better suited to the Mk3 wheel diameters etc? What would be the most drivable and rev the lowest at 60mph etc


Any advice appreciated


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## Prof315 (Jan 5, 2009)

coons88 said:


> I'm mid project for a Mk3 1.8t swap. I have 2 gear boxes, an 02A from a Mk3 GTI 16v, and an 02J from a Mk4 GTI 1.8t.
> 
> The 02J would be the strongest, I know that. But in terms of ratios, any opinions on what would be better suited to the Mk3 wheel diameters etc? What would be the most drivable and rev the lowest at 60mph etc
> 
> ...


O2A and 02J transmissions have similar strengths. I like the 02J differential better because of the "minislip" limited slip that is in them. What I did was use the parts from several 02Js and 02As to get the final drive and gear ratios I wanted for my car. What codes are the boxes you have?
( the 02J is probably what you'll want ratio wise)


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## coons88 (Aug 20, 2008)

Swapping the gears to make a hybrid box is not a bad idea at all.

The 02A is - CDA 11 045
37 0500

Not sure what the 02J code is, I don't have the box handy to go and check. But it would be 99-01 year Mk4 GTI, 150hp version 1.8t


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## chc-rado (Nov 20, 2008)

Prof315 said:


> O2A and 02J transmissions have similar strengths. I like the 02J differential better because of the "minislip" limited slip that is in them. What I did was use the parts from several 02Js and 02As to get the final drive and gear ratios I wanted for my car. What codes are the boxes you have?
> ( the 02J is probably what you'll want ratio wise)


Explain this "minislip" limited slip. I have 02J 1.8t with .756 tdi 5th gear in rado now. I had O2A and O2J apart before. I know most 02A trans have press in flanges and tdi 02A and all 02J are bolted in. Where exactly in location is "minislip" it been a while, I tear down new mk5+mk6 0A4 trans, similar to O2J without the speedo gear in them. I'm assuming it's the diff unit, I know those slightly different from O2A and O2J transmission.


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## Prof315 (Jan 5, 2009)

chc-rado said:


> Explain this "minislip" limited slip. I have 02J 1.8t with .756 tdi 5th gear in rado now. I had O2A and O2J apart before. I know most 02A trans have press in flanges and tdi 02A and all 02J are bolted in. Where exactly in location is "minislip" it been a while, I tear down new mk5+mk6 0A4 trans, similar to O2J without the speedo gear in them. I'm assuming it's the diff unit, I know those slightly different from O2A and O2J transmission.


The stub axles (flanges) have a tapered bronze cone and a spring that slide over the shaft. When you bolt the flanges in the springs push the cones against the diff creating a (cheezy) limited slip. You can make it more agressive by shimming the spings.


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## Vegeta Gti (Feb 13, 2003)

TDi 02J here. LOVE IT


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