6 replies to this topic

[al_reidy]

has anyone changed the Diff on honda type R K20a without removing the engine?

i have a plate type diff that is not to my driving style and i want to change it to a quaife.

has anyone done this? without removing the engine from the frame?

[e11evns]

ask kirk he has changed diffs

[cptkirk]

Al, You can do it without removing the whole engine, you will have to remove the front and rear engine mounts and take the N/S rear suspenion arm off as you need to remove the N/S drive shaft. I put a block of wood over the bar that runs under the engine and lowered the engine down onto it to rest, you cant really move the car about as the engine in only held in place by O/S engine mount, so where ever you use to remove it I would advise that it stays there til you can get the G-box back in. I was fortunate enough to use a mates two poster ramp which made the removal possible, I am not sure how easy it would be in a normal home garage situation.

Also a word of warning if you didnt already read it in my build diary, for some reason Z's had used M10 bolts in the upgraded final drive and Gripper diff set up, Honda and Quaife diffs use M11 bolts, I had to have the holes in the final drive opened out to 11mm by spark eroding due to the hardness of the final drive. Just a pre-warn incase the same is true in your setup, expect to pay a bit more and wait a bit longer, Guy at CPL sorted all of this for me, I just dropped the G-box to him and picked it up a fortnight later, although Sheerness (CPL's location) is out of the way from everywhere.

Also I used the Quaife designed for the Atom and I have to say the car puts the power down really smoothly, with no dramas in the corners from the rear. As you will know from looking into the diffs the only downside of the Quaife (Torsen Type) Diff is if one wheel is off the ground it acts like an open diff.

[al_reidy]

Al, You can do it without removing the whole engine, you will have to remove the front and rear engine mounts and take the N/S rear suspenion arm off as you need to remove the N/S drive shaft. I put a block of wood over the bar that runs under the engine and lowered the engine down onto it to rest, you cant really move the car about as the engine in only held in place by O/S engine mount, so where ever you use to remove it I would advise that it stays there til you can get the G-box back in. I was fortunate enough to use a mates two poster ramp which made the removal possible, I am not sure how easy it would be in a normal home garage situation.

Also a word of warning if you didnt already read it in my build diary, for some reason Z's had used M10 bolts in the upgraded final drive and Gripper diff set up, Honda and Quaife diffs use M11 bolts, I had to have the holes in the final drive opened out to 11mm by spark eroding due to the hardness of the final drive. Just a pre-warn incase the same is true in your setup, expect to pay a bit more and wait a bit longer, Guy at CPL sorted all of this for me, I just dropped the G-box to him and picked it up a fortnight later, although Sheerness (CPL's location) is out of the way from everywhere.

Also I used the Quaife designed for the Atom and I have to say the car puts the power down really smoothly, with no dramas in the corners from the rear. As you will know from looking into the diffs the only downside of the Quaife (Torsen Type) Diff is if one wheel is off the ground it acts like an open diff.

thanks for the reply, interesting that there is difference in the atom diff, im guessing weight of the car and rear wheel drive.... im going to call up CPL and get a price. i also found this....
DIY diff removal

but i think if im going to do it i will try and make a proper photo guide to put on here more suited to the mini zcars install.

cheers

cheers

[cptkirk]

Al CPL also fitted a speedo ring to my Quaife ATB, they supply the genuine Honda part at the same cost that Honda charge as I also suffered from the same reverse problem as the speedo ring had also been omitted from my setup, even though I was using a Hondata ECU, you still need the ring to send a signal to the ECU.

You guessed right about the Atom setup, it designed for a light, mid engined, RWD car. If I remember correctly the helix angle on the worm gears was changed from 31deg for FWD to 23deg for the RWD diff, making it less aggressive & therefore suited to the Atom and similar cars, like ours.

[al_reidy]

Al CPL also fitted a speedo ring to my Quaife ATB, they supply the genuine Honda part at the same cost that Honda charge as I also suffered from the same reverse problem as the speedo ring had also been omitted from my setup, even though I was using a Hondata ECU, you still need the ring to send a signal to the ECU.

You guessed right about the Atom setup, it designed for a light, mid engined, RWD car. If I remember correctly the helix angle on the worm gears was changed from 31deg for FWD to 23deg for the RWD diff, making it less aggressive & therefore suited to the Atom and similar cars, like ours.

Thanks for all your information im going to order the ATB Diff, just wanted to clarify the wholes in the final drive issue, if honda used 11mm and Quaife use 11mm, why did you have to widen the wholes on the final drive?
Did you change the ratio's? was it worth it?
my bro now works at Ginetta so im hoping if i can get the gearbox off the car they will fit it.

[cptkirk]

The 3.9 final drive supplied by Z's, for whatever reason, only had 10mm holes which the bolt has to pass through to fix to the diff - the Gripper supplied by Z's also only had 10mm threaded holes in its casing?!?!?! To sum it up all the parts supplied by Z's used 10mm fittings, thats why I had to widen the holes on the FD to accept OEM 11mm bolts, as to why they did this is a question for Z's.

Ratios -

If your asking about final drive rations then: With the 3.9 FD ratio and the big sidewall tyres I am getting 90mph @ 4000rpm in top (6th), I think it was totally worth it.

If your asking about helix angles in the diff then: I fitted the diff designed for the Atom with the 23deg helix angles and I think it was totally worth it, I cant comment on the 31deg FWD diff setup and likewise I cant comment on what is is like to drive with the Gripper as I didnt do any miles with it fitted.

The other thing with the Quaife is its a fit and forget item, unlike plate types that will need servicing from time to time. If you dont see yourself racing or being in a position where one of the rear wheels might be off the ground and causing you to lose time then the Quaife is the way to go as its power delivery is really smooth, no dramas at all.

It is all about personal choice and I like the smooth delivery option, it might not the best for racing but it sure works well out on the roads.