U2Q7 LSD on a 5G Prelude

CARRisma · Post by **CARRisma** » Wed Jan 13, 2016 10:16 am

Question to those who have had U2Q7 gearbox from an ATR fitted to their Prelude, or just the LSD unit fitted in the gearbox - what is your opinion of it? Do you recommend having it done? How much of a difference does it make?

Dino · Post by **Dino** » Wed Jan 13, 2016 10:24 am

Ive had a U2Q7 fitted to a custom built box.

It is better than the viscous LSD that is found in the b4 & T4

As for ratios of the U2Q7, personally I really dont like them.

CARRisma · Post by **CARRisma** » Wed Jan 13, 2016 10:30 am

Yes, I understand about the gear ratios. The U2Q7 has identical ratios to my M2P4. I preferred the M2V5 ratios of my previous 1997 Prelude.

So, what's your opinion on the LSD? Worth it? What's it like during everyday driving? Any disadvantages?

Dino · Post by **Dino** » Wed Jan 13, 2016 10:44 am

U2Q7 LSD is absolutely fine for everyday driving. Its whats fitted in the ATR and thats an everyday car.

The Q7 LSD is a little sharper and more responsive than the viscous LSD of the prelude and is a great upgrade over the lude item, but not quite as good as a quaiffe Torsen LSD.

chrismc · Post by **chrismc** » Wed Jan 13, 2016 1:09 pm

As both a BB1 (with m2b4 lsd box) & an ATR owner- I find both diffs pretty mild compared to the Quaife ATB I used to have in my Golf...both very tame and suitable on a daily

The way that VTECs are all about top end shove means on the road the diffs need considerable persuasion to do their thing...no real torque-steer low down to make the diffs' prescence felt

The u2q7 is a decent box- the ratios themselves are fine IMO- it's only hampered by 17" wheels on the ATR (or 5g if fitting into that!)

A 4.64 FD will sort that out though & brings gearing back to VTEC friendly ITR 98spec equivalent. On my ATR shopping list along with new clutch & lightened fly..

Post by **RattyMcClelland** » Wed Jan 13, 2016 3:17 pm

M2P4 box, mfactory sycros, mfactory 4.64 final drive (best mod ever), mfactory helical lsd stage 1 upgrade.

Sex.

89 UKDM BA4 4WS (resto job!) · Post by **wurlycorner** » Thu Jan 14, 2016 12:15 am

Yeah great...

But to anyone that principally uses their lude just as a daily and isn't into (or able) to get bent over and having a 747 rammed up their arse at supersonic speeds... I suggest Dino and Chris's advice is more relevant to the question?

I have no experience of the U2Q7 box, but have had 6x 4g's to swap between in my lifetime.
It was a long time in them till I sampled the m2b4 over a non LSD 4g box and when i did, I was genuinely amazed/surprised at the difference over a standard box.
If your current 5g box is non LSD (i don't know the codes on 5g boxes) then going on my experience of the m2b4 compared to a non LSD, you will notice a massive difference, even in day-day driving (really!).
And although I have no personal experience, but going on that, what I have since read up on viscous/torsion LSD differences and with what people who have had m2b4 AND U2Q7 say, even if your current 5g box is an equivalent LSD to m2b4, you WILL notice the difference!

Definitely do it, if it's reasonable cost.

Post by **NafemanNathan** » Thu Jan 14, 2016 9:32 pm

I have a U2Q7 in my 5th gen. It's certainly spot on for road driving. I have an ascending chicane on the way back from work (possibly a 30 degree'er)... If ever I put the power down around it in one of my old BB4's with an M2B4 LSD I could still get them to skip slightly on occasion, whereas I've never experienced such with the U2Q7.

The only thing if you're doing motorway miles will be the ratios will be an issue. If I'm jut pootling, I'll put it in 5th at 40mph on the flat.

mercutio · Post by **mercutio** » Thu Jan 14, 2016 10:05 pm

NafemanNathan wrote:If ever I put the power down around it in one of my old BB4's with an M2B4 LSD I could still get them to skip slightly on occasion, whereas I've never experienced such with the U2Q7..

the wider track may also affect that

Post by **Donald** » Thu Jan 14, 2016 10:51 pm

NafemanNathan wrote:The only thing if you're doing motorway miles will be the ratios will be an issue. If I'm jut pootling, I'll put it in 5th at 40mph on the flat.

As said though he's used to that with the M2P4. 5k drone at 70mph gets old