I saw an add from unisteer.com for a power rack and pinion, that is a bolt on up grade for the 69. Has anyone used these? If so are they good, or not? Also how much trouble are they to install?

I have read people having lots of trouble with the u-joints in the steering column
use the search function, its been discussed many times

personally I would just get a really nice 3rd gen style steering box; ATS, lee, DSE someone makes one that is supposed to be valved to act like a rack and pinion

The biggest problem with any aftermarket rack system is geometry. There hasnt been one released yet... that can address the bump steer issue.

The ATS box is a Lee unit... and it feels like, and IMHO even better than rack... without the bumpsteer issues. All components in the steering 'system' and suspension have to be known to really make it work correctly.

Steering arms and bumpsteer correction as well as the amount of available caster are key to getting this correct.

The DSE unit is also a good unit and is similar, but doesnt offer the valving selections that the ATS or Lee boxes can be had with. I am sure Kyle could do it if it were requested... but it too really comes down to set-ups in suspension and other components being used in the steering system.

chicane67 i don't want to start an argument but i have spent some time plotting out the unisteer system on the performance trends analizer and it is really not to bad. we came up with a maximum of -.03 of bump steer in 2.5" of travel (-1 to +1.5) from our ride height (that will differ on all cars) with our new sub frame.the biggest issue is header clearance. the black
camaro we built has a unisteer kit in it and it drives wicked, good response, steers well, no noticable tire wear, all around good
i know you are knowledgable in the suspension department so what is an acceptable amount of bump steer and what is an acceptable amount of travel to measure it in.
i would think in the "real world" if you could get -.050 bump in 3" of travel -1.5 to +1.5 that would be good. i think thetire tread would move .050. what do you think. obviously 0 is better but i doubt most people could even measure accuratly enough to get that close???

chicane67 i don't want to start an argument but i have spent some time plotting out the unisteer system on the performance trends analizer and it is really not to bad. we came up with a maximum of -.03 of bump steer in 2.5" of travel (-1 to +1.5) from our ride height (that will differ on all cars) with our new sub frame.the biggest issue is header clearance. the black
camaro we built has a unisteer kit in it and it drives wicked, good response, steers well, no noticable tire wear, all around good
i know you are knowledgable in the suspension department so what is an acceptable amount of bump steer and what is an acceptable amount of travel to measure it in.
i would think in the "real world" if you could get -.050 bump in 3" of travel -1.5 to +1.5 that would be good. i think thetire tread would move .050. what do you think. obviously 0 is better but i doubt most people could even measure accuratly enough to get that close???

Ok... ... ...no arguement needed. :D

But... that is an analizer, not real world. True full bump measurement would cover 4.5+ inches, not 2.5 inches. "Designed ride height" to factory bump is -2.375 to -2.4375" on average... so that will add to your findings. It also makes a difference to where you are taking your measurements from. An inch and a half at the spindle isnt really moving in reality... considering a street driven (or track for that matter) chassis.

If you are limited to -1.000" of travel... you are inducing other issues from being below "designed ride height." It will soften both the camber and castor curves by a measurable amount. You will also need abnormally huge spring rates to keep the chassis off of the bump stops and inducing dangerous handling and steering issues.

Real world... is what we did with the AFX spindle and a standard rear steer configuration. With a little over 4.5" of travel we got it to hold 0.030" or less through full cycle. Ill say it was less than 0.027" over that same 4.5" travel... but that was never printed. http://www.ls1tech.com/forums/images/smilies/LS1Tech/secret.gif

The easiest way to decrease bump on a factory sub is to... increase positive caster. 6+ positive is a good number to throw around from the get go.

If you really want to play around with the numbers... the one thing that you should really concentrait is... the scrub radius.

I have the manual rack from unisteer and you can't beat it with a stick and a piece of bacon. Installation was more difficult then I thought, the instructions were wrong, but once installed, worth every penny. I am actually going to go with a power rack this spring/summer and will use unisteer again.

curious as the the rest of the suspension components are installed with the unisteer rack kit you are useing succesfully.

specs?


Chris :cool:

right now, it is pretty basic...2" hotchkis drop springs, 1-1/8" sway bar drop blocks in the rear, everything else is stock.....coming...hotchkis upper/lower tub arms, ats spindles, baer brakes, the new style gbar, unisteer power rack. While I am at it, I will go ahead add a/c. I will be have hotchkis shocks(bilstein?)

if you can get a box to work better, why even bother with a rack?

The only reason I can see for going with a rack is that it MIGHT make installation of an LSx engine easier. Even then it's not so obvious. Other than that I see no reason to use a rack over one of the updated boxes.

Just my two cents,
Don

Doesn't Flaming River have a rack kit? Has any body tried it?

Dave

The only reason I can see for going with a rack is that it MIGHT make installation of an LSx engine easier. Even then it's not so obvious. Other than that I see no reason to use a rack over one of the updated boxes.

Just my two cents,
Don

some people do it to save a few pounds...

Personally, I have an AGR 12:1 box.

How do the Lee and DSE boxes compare to the AGR? I’ve heard nice things about the Lee's but are they worth the extra coin for a street car that will occasionally race?

If I was doing it over, I'd buy a Lee box from ATS.

(my AGR box had bad machining and blew the snap ring and seal out around the sector shaft in less than 200 mi. AGR fixed it for free even though the 90-day warranty was past, but it took them about 6 weeks to actually get it fixed and get it back to me)