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Kumho V70A Tyres?

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Yeh, its getting near tyre replacement time again, the Dunlop DO1J's are just about stuffed. V70A's have become available at a good price, significantly cheaper than the Dunlops.

The Z does high speed circuit work, usually around 5-7 laps per 'race', called sprints because the start is staggered and times only count. And it gets very hot here in summer so I'm thinking of a medium-hard compound.

So it would be good if those of you who have used the V70A's could give their opinion, compared with Toyo and Yokohama R tyres if possible. The tyres will be used for dry circuit work only, they are changed at the track, no wet weather use.

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Richard,

Sorry to dig this up but did you go with the V70As? And how did you find them? I'm very seriously considering them for my zed.

Dave

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Went with Kumho's Dave but at the time only the Victoracers were available in the required size, not the V70A's. Good value for money, I probably will go with V70A's next time. What size are you after?

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I checked out Kumho's Austrailian site, and it looks like the ECSTA V700 sold here in the States. I have these and am very happy them. These are the only ones I've ever used and there are so many variables, but they seem to be comparable to what other guys are using.

I'm contemplating purchasing a set of V710's, but have heard mixed results with the wheel to wheel guys. Some say they're really good for the first 10 laps, but then fade off quickly. The autocrossers really like them, which would confirm this in my mind.

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I just took the rims in to get 225/50R16s V70As put on them after getting the lips rerolled (2nd hand simmons). Will take pics when they're on the car.. poxy white.. but anyway.

Thanks for the advice. :)

Dave

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preith,

I've heard tell the V710s have been recalled due to some cars having serious problems. The replacement is apparently the V800 which looks something like this: http://www.kumhotyre.com/products/details.asp?curpage=110&brand_pkid=&tyre_type_pkid=&width=&aspect=&speed=&Rim=&sub_type=&stdrim=&tube_type=&sidewall=&load_index=&load_index2=&pattern_name=&SearchType=

This is just rumour though.. make of it what you will.

Dave

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preith,

I've heard tell the V710s have been recalled due to some cars having serious problems. The replacement is apparently the V800 which looks something like this: http://www.kumhotyre.com/products/details.asp?curpage=110&brand_pkid=&tyre_type_pkid=&width=&aspect=&speed=&Rim=&sub_type=&stdrim=&tube_type=&sidewall=&load_index=&load_index2=&pattern_name=&SearchType=

This is just rumour though.. make of it what you will.

Dave

The V710's were discontinued temporarily due to sidewall failures, or something similar to that, but were reinstated in the spring of this year. If they've been discontinued again, it's news to me. Even with that blemish on the record, since then they've received rave reviews from the autocross crowd who say they're better than the Hoosiers.

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Preith,

Yep that sounds like it. Good to hear they are back, I heard that if you could get them not to die they were unbelievable. I wonder how long until they filter down under.

Are they readily available in the states? The V710s I mean.

Dave

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Preith,

Yep that sounds like it. Good to hear they are back, I heard that if you could get them not to die they were unbelievable. I wonder how long until they filter down under.

Are they readily available in the states? The V710s I mean.

Dave

From what I've read on the SCCA forums they are in somewhat limited supply, but nobody on that board has had any problems getting them.

Per my 1st post, I'm really interested in buying a set but am a little apprehensive how they will react to road racing.

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Tis a worry to be sure, noone likes to spend money to have the tyres disintegrate. What size rubber are you running in the V700s? And what compound?

Dave

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Tis a worry to be sure, noone likes to spend money to have the tyres disintegrate. What size rubber are you running in the V700s? And what compound?

Dave

225/50/15's, and I don't know what compound. As far as I know there isn't any selection available.

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Sounds good. Looks like you've got a fair bit of camber on the front there, mind if I go kinda of off topic and ask what castor/radius rods and tie rod ends you are running?

Many thanks,

Dave

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Sounds good. Looks like you've got a fair bit of camber on the front there, mind if I go kinda of off topic and ask what castor/radius rods and tie rod ends you are running?

Many thanks,

Dave

I actually haven't played much with camber. There was a very good link on Zdriver.com in the racing section which had a guy's setup on his IT car. I figured I would copy his as a starting point. The fronts are at about 3 degrees and the rear 2.5 degrees. This past summer was my first serious attempt at road racing and I really haven't played with the setup too much. I figured my car feel should get better first.

I have the Arizona Zcar chromoly arms and tension rods (castor/radius), which utilize a clevis pin on the control arm and a rod end on the chassis side for a solid link. Right now the tie rod ends are actually stock units, but I plan on converting over to rod ends for that as well this winter (heh, your summer). I have the "bump steer" spacers as well. I've heard many guys complain of instability during hard braking if their bumpsteer isn't just right, but I haven't bothered trying to adjust anything and it's been rock solid. I think part of that may be because of rigidity, there is 1" square tubing connecting the tension rod mounts to the front corner of the rocker panels. This is an old trick and I can't take credit for it.

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The setup which has worked well for me in high speed circuit work with the Kumhos is 3.5 degrees negative camber front, 1.5 rear, with a bit of front toe out/rear toe in and a bit more castor than stock. The car is fine to drive on the road with those settings too, quite stable.

Prieth, that is the first time I've heard of others running a bar from the tension rod pickup points to the front of the rocker panels. Mine was done like that some years ago, plus it has a removeable tube running across under the sump to the pickup points on each side as well.

The end of straight braking area at the circuit I usually go to is very bumpy yet the brakes can be slammed on hard at ~200kph no worries.

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Rocker panel is the area under the door. It is a frame rail really that ties the front of the car to the back and supports the floor.

Do you guys have any pics of your braces? I was thinking of doing the brace to the rocker along with a brace from the crossmember back to the TC bucket inside the engine compartment kind of turning the crossmember into a K member.

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Rocker panel is the area under the door. It is a frame rail really that ties the front of the car to the back and supports the floor.

Do you guys have any pics of your braces? I was thinking of doing the brace to the rocker along with a brace from the crossmember back to the TC bucket inside the engine compartment kind of turning the crossmember into a K member.

Man, I have GOT to get a digital camera! Unfortunately, I don't have any pics, but I think it's pretty self explanitory. I don't have any data or proof to back it up, but an old timer I used to hang out with, has tried both methods seperately (across the tunnel and to the rocker panels) said they both have the same affectiveness. So it was my guess that both isn't needed.

It also makes for something else to get in the way during engine/trans removals and installations. I suppose it would be pretty easy to fab some kind of removable one if you really wanted both.

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I'm just trying to figure out where you attach to the rocker. I just took my fenders off and had some rust on the passenger side so I've been looking right at this area. The rocker protrudes past the floors and looks kind of like a knife blade that sticks out ~2 inches. The outside part of it is shaped like a wedge, so not too easy to connect there either. It'd be REALLY easy to connect to the floor right next to the front part and tie in with an L shaped plate. Maybe that's the answer...

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I'm just trying to figure out where you attach to the rocker. I just took my fenders off and had some rust on the passenger side so I've been looking right at this area. The rocker protrudes past the floors and looks kind of like a knife blade that sticks out ~2 inches. The outside part of it is shaped like a wedge, so not too easy to connect there either. It'd be REALLY easy to connect to the floor right next to the front part and tie in with an L shaped plate. Maybe that's the answer...

I don't seem to remember mine being 2", maybe an inch at best. I ended up cutting the end to a point, or a knife point, and putting as much surface area of the 1" sq tubing as possible on the rocker side, but yet still have enough area to form a T weld if that makes any sense. I did not use any plating to reinforce it on the floorboard side. All in all, I thought it was a pretty easy mod.

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