128 replies to this topic

[al_reidy]

does anyone else experience the back end feeling loose when coming off power at high rpm?

I do too, I'm going to change the steering arms and track rod ends next week to see if that improves it.

I asked Z-Cars about it a while ago and got this response:

try six clicks from zero on all four shocks
zero being fully anticlockwise till you reach the stop
check the steering racks tight on the subframe or bulkhead depending which you have
also have you got a good stiff steering column on it
if the column can flex around it makes the car feel queer

interesting. i have the zcars welded steering column which dosnt flex at all.
i have new rack and new steering arms with self made rose joint lowering pins. all tight with no play on the rack....
my question is now.... does anyone have a zcars mini that doesn't feel loose like this?


oh and I'm already on 6 clicks....

Edited by al_reidy, 10 May 2012 - 01:20 PM.

[Mini Type R]

I haven't gone through the whole post but the cars mentioned on the last page were all Vtec engined, do any of the bike engined cars have the same problem?

[cptkirk]

interesting. i have the zcars welded steering column which dosnt flex at all.
i have new rack and new steering arms with self made rose joint lowering pins. all tight with no play on the rack....

oh and I'm already on 6 clicks....

Me too, with column, steering rack and 6 clicks...

I haven't gone through the whole post but the cars mentioned on the last page were all Vtec engined, do any of the bike engined cars have the same problem?

Thats a good question......

[al_reidy]

I have just been out for a drive, nice weather no rain. dry roads.

Double checked tyre pressures,shocker clicks and tightness of steering rack.

If i drive at 40mph and swing the steering 1cm either side of dead center it has a massive affect on road position.
perhaps dialling this out will help the loose feeling at the back and give more confidence at high speed on back roads.
anyone know how to do this? perhaps more toe in?

[benmoffat]

Not anywhere near getting mine on the road yet. But reading your problems maybe the following could help?
If you are having too much steering from little input, then if you have a quick rack then change to a normal rack. Also I'm sure it would be possible to have some special steering arms made that had the bolt for the rack closer to the hub, so less leverage on the steering.

I think that would have less effect on the steering and make it feel
Less direct. Also have you tried a larger steering wheel? I know how much difference that makes going from a 13" to a 10" wheel, maybe that's worth a try.
I guess it may have something to do with the kit using standard mini components, the steering rack and hubs, column etc are all designed for steering and handling with a heavy engine weighing down on it. Taking the engine out must change the dynamics of all of that.
Like I say I havent driven mine yet but thats what I would guess

Edited by benmoffat, 13 May 2012 - 10:24 AM.

[al_reidy]

Not anywhere near getting mine on the road yet. But reading your problems maybe the following could help?
If you are having too much steering from little input, then if you have a quick rack then change to a normal rack. Also I'm sure it would be possible to have some special steering arms made that had the bolt for the rack closer to the hub, so less leverage on the steering.
I think that would have less effect on the steering and make it feel
Less direct.

Its a standard rack, i think shortening the arms will have the opposite effect, perhaps this might help?
expensive though.... http://www.minitasti...teeringarms.htm

Also have you tried a larger steering wheel? I know how much difference that makes going from a 13" to a 10" wheel, maybe that's worth a try.

i have an MX5 mono steering wheel so that i could pass the IVA test. its about 13 to 14" but i know what your thinking.

I guess it may have something to do with the kit using standard mini components, the steering rack and hubs, column etc are all designed for steering and handling with a heavy engine weighing down on it. Taking the engine out must change the dynamics of all of that.
Like I say I havent driven mine yet but thats what I would guess

Yeah i guess. it does seem odd that we all feel the same about the handling. even with the different front subframes in use. I'm using the one with the steering rack attached to the body in the orig place, and cptkirk has the later frame with the subframe holding the steering rack.

its so frustrating not being able to have confidence driving it....

[Pete649]

If you change the steering arm length, don't you mess up the Ackerman geometry? Or can you compensate for the steering arm length change? I'm not sure how those minitastic arms work.

[al_reidy]

If you change the steering arm length, don't you mess up the Ackerman geometry? Or can you compensate for the steering arm length change? I'm not sure how those minitastic arms work.

i read another post about that (i had to google Ackerman geometry, thanks wiki ), i can't see why they wouldn't have thought about that when minitastic designed them. Ive met the guy. he's an intelligent thorough man.

plus if you extend them in the same angle it shouldn't matter?
apprently metro arms are in the same angle but extend 30mm compared to the 17mm extension of the mini tactic ones. so I'm guessing if you use the metro arms you can hardly turn at all !

[al_reidy]

I have made some improvements in the way the car handles. I tightened everything I could find on the front subframe. The surprises were that the tie bars were quite loose. But not in the way you might think, the powder coating had separated from the metal and was able to spin in a cap around the mount. The frame was actually starting to catch surface rust!
I pulled the paint 'cap' off and tightened it again. The bottom wishbone rise joints have play in them which won't help. The others all over the frame felt like play but actually were not tight enough for the rose to be nipped by the mount.
The result is that it now actually feels quite good and predictable, in the dry at least.
It's still not amazing at high speeds but its getting there.

Edited by al_reidy, 21 May 2012 - 07:51 PM.

[cptkirk]

I have made some improvements in the way the car handles. I tightened everything I could find on the front subframe. The surprises were that the tie bars were quite loose. But not in the way you might think, the powder coating had separated from the metal and was able to spin in a cap around the mount. The frame was actually starting to catch surface rust!
I pulled the paint 'cap' off and tightened it again. The bottom wishbone rise joints have play in them which won't help. The others all over the frame felt like play but actually were not tight enough for the rose to be nipped by the mount.
The result is that it now actually feels quite good and predictable, in the dry at least.
It's still not amazing at high speeds but its getting there.

Thats a good start.

When I had my engine out recently I checked the rear rose joints and all four had an amount of play in them. I was talking about this to a mate of mine that works with historic formula 1 cars and he said to use NMB rose joints, they are about £70 per rose joint but they are aerospace quality. The ones used by Z's are a fair quality but nothing like the NMB's apparently. Over time I am going to replace all the RJ's with NMB's - Al this might also help with yours......

If I get any spare cash I would like to uprate the springs on the car as although they are nice and soft when it comes to long drives, a little harder should help with the weight shift by reducing the see-saw feeling as you lift off. The biggest problem with suspension is its all a comprimise, too hard & it will rattle your teeth but help with the see-sawing and soft is good for regular road but just a bit too soft.

[al_reidy]

I have made some improvements in the way the car handles. I tightened everything I could find on the front subframe. The surprises were that the tie bars were quite loose. But not in the way you might think, the powder coating had separated from the metal and was able to spin in a cap around the mount. The frame was actually starting to catch surface rust!
I pulled the paint 'cap' off and tightened it again. The bottom wishbone rise joints have play in them which won't help. The others all over the frame felt like play but actually were not tight enough for the rose to be nipped by the mount.
The result is that it now actually feels quite good and predictable, in the dry at least.
It's still not amazing at high speeds but its getting there.

Thats a good start.

When I had my engine out recently I checked the rear rose joints and all four had an amount of play in them. I was talking about this to a mate of mine that works with historic formula 1 cars and he said to use NMB rose joints, they are about £70 per rose joint but they are aerospace quality. The ones used by Z's are a fair quality but nothing like the NMB's apparently. Over time I am going to replace all the RJ's with NMB's - Al this might also help with yours......

If I get any spare cash I would like to uprate the springs on the car as although they are nice and soft when it comes to long drives, a little harder should help with the weight shift by reducing the see-saw feeling as you lift off. The biggest problem with suspension is its all a comprimise, too hard & it will rattle your teeth but help with the see-sawing and soft is good for regular road but just a bit too soft.

I like the idea of the mega rose joints. you don't know what sizes are in use do you?

the harder springs might be more snap oversteer though?
i looked over this thread the other day and remembered your thoughts on the dampers and the rebound control on higher models, did you go for that in the end?

[cptkirk]

Al

sorry for the delay, no I didnt buy any, I just spent about 1.5k over the winter doing the intercooler, tuning and other bits so cant justify the money right now.

Unsure as to the poundage currently, maybe Z's can help out if they are lurking on the forum????? I think I saw someone had put the poundage somewhere way back in time, maybe a search will find them.

Rose Joint sizes are definitely not 1/2" hole by 1/2" UNF thread as I bought some to find that the thread is bigger, I think its 5/8" UNF thread, maybe a mail to Z's to clear that up would be a good idea....

I am flat out trying to get mine ready for the 2nd June track day at Goodwood, havent driven it since September and now its 50bhp & 36 lb/ft more than it was before so it should make for an interesting day.....I would love to get to the bottom of the handling issues with the VTEC cars, but I fear it might take cash to do so and I dont have it right now. I will try and ask my mate that I mentioned before, see if he's got any ideas or might knwo someone that does..

[Mini Type R]

I've just changed the standard trackrod ends and arms to cooper S arms and lowered rose joint, using the parts list earlier, in order, arm, spacer, tapered sleeve, rose joint, nut.. The rack is now parallel to the lower wishbone but having driven it this morning i can't go over 40 on roads that were comfortable at 70 without it pulling all over the place, it's not even a bad road surface. Even on a smooth dual carriageway i couldn't risk going over 60 without it feeling like it could change lane at any time.

Before i change it all back again is there something i could have got wrong?

[al_reidy]

I've just changed the standard trackrod ends and arms to cooper S arms and lowered rose joint, using the parts list earlier, in order, arm, spacer, tapered sleeve, rose joint, nut.. The rack is now parallel to the lower wishbone but having driven it this morning i can't go over 40 on roads that were comfortable at 70 without it pulling all over the place, it's not even a bad road surface. Even on a smooth dual carriageway i couldn't risk going over 60 without it feeling like it could change lane at any time.

Before i change it all back again is there something i could have got wrong?

did you change the tracking when you did that?

i would check the actual bump steer to see if you have actually added bump steering rather than taken it away.
I disconnected the shocker, and got a right angle metal box next to the wheel, then you lift the wheel assembly look at how much it steers going in the normal travel range.
mine is now about 5 mm off no steering at all.

does your rack mount to the body or frame?
can you flex the steering arms when the wheel is under load, as in sit in the car and play around with the steering getting a mate to see if the arm assembly flex's. if it does reduce its height so there is less lever etc etc.

[Mini Type R]

I had the tracking checked which was a bit out, but made no real difference to the handling.

The rack is mounted to the body. Last night I removed the spacers which made it much better, but not as good as it was before. I'm hoping that somewhere between no spacer and the full spacer there'll be an improvement.