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-   -   Fitting 275 Hoosiers on an NB with offset upper bushings (https://www.miataturbo.net/wheels-tires-78/fitting-275-hoosiers-nb-offset-upper-bushings-77797/)

Leafy 03-06-2014 08:44 AM

Dont you know, you need all of the steering angle to drift with 275s.*






*not really, just put heat cycled out Rs on the back and decent As on the front and it'll drift with just gentle caresses on the steering wheel

bbundy 03-06-2014 12:12 PM


Originally Posted by codrus (Post 1109056)
What are your concerns about the V8R arms? How would you modify the stock ones? Just lengthen them by some fixed amount and lose the extra adjustment or would you put the eccentric bolt in as well?

I have the RB 1.25" sway bar and even the 225s crash into it at full lock, so yeah I don't expect to get the 275s that far over. Fortunately I don't have to parallel park the car at an autox. :)

--Ian

I think mine are like their 4th redesign due to strength issues they had. I still don’t like some of the geometry and weld locations they have for attaching the outer end plate metal parts onto the large round tubing. I believe they have some fairly substantial load paths going through short sections of weld on tube walls. Looks like they got all the strength issues sorted but still may have some longer life fatigue issues yet next to some key welds.

My original thought on the stock ones was to just move the holes. But after having the V8R ones I come to realize the benefit of having the outer adjustment if you ever want to do any self-alignment with primitive tools so I might would try and get the cam bolt features incorporated.

That outer cam bolt and the other bolt both need to be tight as hell because with that much grip they tend to slip. Probably a good Idea to use higher strength steel like 4130 for the hole slots to keep from yielding it under the washer with repeated use.
.

bbundy 03-06-2014 02:57 PM


Originally Posted by Savington (Post 1109062)
Whining about how your 275s hit your _________ at full lock makes you a tremendous baby. Just FYI :party:

Hitting the tire on the sway bar at full lock isn’t a concern. just nice to have it go away completly. Having the A-arm machine away the rim lip within a few revolutions at full lock I think is an issue and should be addressed with some steering stops if you have that situation. 10’s with no spacer will just kiss the rim lip on stock A-arms at full lock. 11’s would have about ½” of interference.

Savington 03-06-2014 02:58 PM

Or you could just not use full lock, like I've done in every Miata I've driven since 2007 :party:

codrus 03-06-2014 04:35 PM


Originally Posted by bbundy (Post 1109250)
Hitting the tire on the sway bar at full lock isn’t a concern. just nice to have it go away completly. Having the A-arm machine away the rim lip within a few revolutions at full lock I think is an issue and should be addressed with some steering stops if you have that situation. 10’s with no spacer will just kiss the rim lip on stock A-arms at full lock. 11’s would have about ½” of interference.

9s will contact the A-arm at full lock if you have the offset upper bushings. At least, they will if you have the steering rack one spline off-center the way I do (I really ought to fix that one of these days).

I've done it a few times when maneuvering the car onto the trailer, and it's not that big a deal. It does scar up the painted edge of the rim, but it's not going to destroy anything as long as you don't hold it there.

From a conversation I had elsewhere, it sounds like most CSP Miatas have offset bushings and 15x10s with a spacer, so maybe there's hope there yet. I guess I just need to find some more wheels. :)

--Ian

ZX-Tex 04-13-2014 11:11 AM

FWIW it is easy to make steering rack stops from a piece of SCH-40 PVC pipe (2" IIRC). Takes less than 30 minutes to fab and install. Easy peasy.

k24madness 04-13-2014 03:00 PM


Originally Posted by bbundy (Post 1109173)

My original thought on the stock ones was to just move the holes.

I have a solution that should work well. It involves moving the ball joint out 1/4"-3/8". If my math is correct that's about .5 to .75 degrees of camber. More that enough IMHO.

I will send you some pics if you want to take the same approach.

Leafy 04-13-2014 10:24 PM

Still having a strugglefest here myself. I finally have some sticker hoosiers, wow theres a lot more rubber here than the scrubs I've been buying. I added packers until it didnt rub at the stock height xida bump stops. That resulted me being on the bump stop before even hitting static ride height. Took the 1/4 of a bump stop I had left over from making the rears match emilio's installation instructions and put that in with a spacer. I'm at ~5/8" of bump travel now with it setup to not destroy the tire on shock tower, AND also a 6mm spacer making my total offset +13. Any more than +13 and it will rub significantly on course on the back of the wheel well. If I went to like +6 offset then it would clear the shock tower and I'd be able to run over 1.5" of bump travel. I'm beginning to think my car is more bent that originally thought, lol.

bbundy 04-22-2014 06:19 PM


Originally Posted by ZX-Tex (Post 1121117)
FWIW it is easy to make steering rack stops from a piece of SCH-40 PVC pipe (2" IIRC). Takes less than 30 minutes to fab and install. Easy peasy.

I may have to do this. the 11" wheels hit the 2.25" ID springs before full wheel cut. Rubs through the powder coat real fast.

Leafy 04-22-2014 09:29 PM


Originally Posted by bbundy (Post 1124245)
I may have to do this. the 11" wheels hit the 2.25" ID springs before full wheel cut. Rubs through the powder coat real fast.

But even with the 10" wheels they rub on the springs, just enough to take the powdercoat off.

ZX-Tex 04-22-2014 10:44 PM


Originally Posted by bbundy (Post 1124245)
I may have to do this. the 11" wheels hit the 2.25" ID springs before full wheel cut. Rubs through the powder coat real fast.

Mine are rubbing on my swaybar. Anyway it is a really easy fix. I think there is a thread about it somewhere around here. I might be wrong on the PVC diameter, but essentially you just cut the pipe to the length you need for the bump stop, cut out about 1/4-1/3 of its circumference so it is c-shaped, pull off the inside end of the tie rod boot, clip the pipe onto the rack, put the boot back, done. The pipe hits the inner tie rod on one end and the rack housing on the other, shortening the rack travel. Add the spacers on both sides obviously. Works great. Only disassembly required is pulling back the boot, which is easy.

1999monster 04-29-2014 07:57 AM

I'm new to this, can some one quickly explain the offset bushing, or post a pic of what it looks like?

Thanks

Leafy 04-29-2014 08:15 AM


Originally Posted by 1999monster (Post 1126385)
I'm new to this, can some one quickly explain the offset bushing, or post a pic of what it looks like?

Thanks

The hole in the bushing is drilled offset.

Seefo 04-29-2014 10:34 AM


Originally Posted by 1999monster (Post 1126385)
I'm new to this, can some one quickly explain the offset bushing, or post a pic of what it looks like?

Thanks

https://www.google.com/search?q=offs...w=1432&bih=942

codrus 04-29-2014 12:13 PM

Offset bushings allow you to effectively shorten (or lengthen, but there's little reason to do that) the upper A-arm, by moving the pivot point closer to the upper ball joint. There are some useful photos in the ISC installation instructions.

--Ian


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