Want_a_v8

DISCLAIMER: The first part of this thread is me explaining my theory/plans/thoughts I've come to after a lot of searching. I put the actual questions at the end. Also, I'm not a master of suspension geometry, I only know the basic idea.

So I've been planning a rack and pinion conversion on my trans am. Before you all freak out, there's a good valid reason for this. I know this has been a controversial topic in the past, but this is the best option for me for my plans for this car. This car is going to be a track/drift car. Its going to see a lot of fast lock to lock steering, probably some contact in the front suspension area (door taps, crashes, etc). and most importantly, really high angle(55-70 degrees). I can't spend hours figuring out what part of the oem box based steering has bent, broken or what have you. Not to mention the current steering setup is worn out pretty badly. A rack and pinion is the best way to eliminate the mass of parts that could go wrong, tighten up the whole front end, cut weight on the front (trying for near 50/50 distribution), and most of all, make track-side diagnosing/ fixing WAY easier. (for me of course)

Ok, so I've been spending an almost unhealthy amount of time researching rack and pinion threads, part numbers/compatibility, reviews for kits, advantages/disadvantages, knuckle modifications, etc lately, and I've come to a general consensus.

For the most part, everything I've read says that to do a proper MANUAL rack conversion, you need a conversion crossmember (or custom mount), a pinto rack, and modified drop spindles to account for bumpsteer. I've seen some back and forth on whether the modified spindles are actually necessary, but for the sake of what I'm doing lets say they are.

For a POWER rack conversion, I haven't really seen much helpful information or actual completed swaps.

So here's what I'm theorizing... Assuming I'm swapping to a tubular x-member, I believe that a mustang 2 rack should bolt up to the pinto mounts. Reason being, I have yet to find a reputable power pinto rack that exists or isn't custom made. BUT, the mustang 2 and the pinto racks are interchangeable as far as I've found, and there are power mustang 2 racks available. Now for the sake of theory, assuming the racks ARE interchangeable, I should be able to put the power rack in the car no problem. For the issue of the actual power steering pump and lines, I would be using an electric pump from an mr2, as it's compact, and you can remotely mount it without needing any conversion brackets for the accessory drive or anything. It's a pretty common swap in my area for a lot of race cars so I know it should work fine.

Now for the control arms. Since this is going to be drifted, the control arms are going to be extended 3-5 inches to widen track width and give clearance for angle. I'm not 100% sure if I'm going to use modified stock ones or high angle friendly tubular ones (L shaped instead of A shaped). The company I've been talking with who might be modifying/building the arms will also supply the proper length tie rod ends and/or rack spacers to properly set the rack. My theory here is that lengthening the track should help in alleviating the issues I've read about most racks being too long for factory track.

The knuckles will be some sort of modified oem style knuckle. Typically for drifting, the tie rod mount gets chopped off and re-welded way closer to the body of the knuckle so as to allow for more angle at lock. In theory, this should also make the ratio feel faster, as the ratio remains the same for more travel of the rack. In the threads I've seen addressing the bump steer modified drop knuckles, this is actually done to a really minor degree, so drastically relocating the mounting point should help alleviate any of the commonly talked about issues the manual rack would come with.

Ok. Now that I've finished rambling- I mean explaining my thought process, here are my questions.

Does anyone know if the mustang 2 racks will actually swap over/ has anyone used or heard of someone using one?

if the mustang 2 rack doesn't work, does anyone know of another compatible POWER rack for the spohn/bmr r&p conversion X-member?

Does anyone more knowledgeable in suspension geometry know how the extended LCA's affect the rack conversion?

Does anyone more knowledgeable know how the cut knuckle setup will affect the rack conversion/ bumpsteer issues?


If anyone has any input that could help me out here, it would be great to hear from you.

Thanks!

sofakingdom

iTrader: (1)

The usual problem people have with r&p conversions, besides just bolting up the rack, is that the range of motion is MUCH smaller than what the steering linkage in a worm-gear system provides. You end up with the wheels only turning about half as far at the max.

Usual solution is, shorten the steering arms on the spindles. Obviously not a trivial matter for a backyard mechanic; esp not when you consider what happens if some weld or something fails.

"Power" is never really a problem. You just use a power rack and hook it up to a PS pump. There's very little difference from one pump to another as far as how they work. Once again it becomes a matter of mechanically adapting the lines and stuff.

AFAIK Mustang 2 is the same thing as Pinto. Same basic platform. Kinda like the Camaro was to the Nova in 1967.

I don't know anything about "drifting". Something I try to avoid. I try to achieve the highest possible traction at all times. No idea how any of this would have any effect on sliding sideways, or why the steering that comes on the car wouldn't work just fine for that. I have nothing to offer you on how that works.

Want_a_v8

Well, in contrast to popular belief, Drifting is actually all about traction. For formula drift and most other competitive drifting series, the common tire setup is usually a 285 or 295 low treadwear racing style with super low tire pressure. you want as much forward and sideways bite under throttle as possible. Something like a Falken tire is pretty common, hence the Falken tire team

That aside, Like I said, its really common in drifting to shorten and relocate the steering arms drastically to increase the steering angle. So by extending the LCA, and changing the steering arm on the spindle, It should have little to no issue with any of the common issues of the rack conversion, all the while increasing the steering angle, yes?

tvc 15

I admire your enthusiasm, but doing what you want won't be easy.

Want_a_v8

Thanks!

Yea, I know this isn't the ideal chassis to use for drifting stock, but out of the box it's a hell of a lot better preforming over all than a stock say 240sx, or even a new staple of the drift community, the mustang. It has double the horsepower, almost triple the torque, and handles a lot better stock (at least the ones I've driven).

The only real downside of the chassis is the lack of angle and the arguably outdated steering setup, hence my wanting to change to rack and pinion.

I've been doing a bit more research into the overall manual side of the steering thing, and I'm thinking I might run it manual for a little while, then have a suspension shop help me design a better setup for the power steering. Reason being, the manual racks mount differently than the power ones, and while they're interchangeable in a stock form, for the aftermarket suspension setups and conversions, they sadly aren't.

Does anyone have any more specific input or personal experience on the actual conversion though?

Thanks!

V6canvas

iTrader: (1)

Well, while this is not my personal experience, I think it's the best fit for information I know of on here. This is a C4 'vette front end swap, he did a thread on here and posted some good videos on youtube. It may be a bigger project than what you're looking for (maybe not?) the car ended up significantly lighter (all front end too!) and a better suspension geometry. While he wasn't going for a drift set up, it is at least a solid starting point.

Thread


In for updates!

//<86TA>\\

iTrader: (14)

"Outdated" or not, the stock steering system works well and is very reliable. It has akerman issues in stock form but if you shortening the steering arms and altering the geometry, why not just keep what's already there? I know the stock box is a bit heavy but there are a lot better places to save weight than heavy parts down low in the chassis.

I modified a set of spindles a while back, shortened the arms, moved the mounting point outboard in an attempt to.correct some of the akerman issues and fit wide front wheels. The results were steller to say the least, and performance with the factory steering system was fantastic. I swapped the factory threaded toe rod adjusters for longer pieces commonly available from many outlets and used rod ends for the outers with threaded studs in the knuckles to help correct the bump steer, which was minimal.

My advice would be to modify the front end suspension and knuckle first and see how the factory parts perform. Then see if you really think the rack and pinion is needed. The replacement parts for the factory setup are not that expensive at all compared to trying to swap in a rack and pinion.

And FWIW, 50/50 is going to be extremely hard to reach without either adding a lot of weight to the rear or moving the engine back a lot.

tvc 15

^ What he said.

Want_a_v8

Well like I said, I want to simplify everything, to save myself from the trouble trackside, and box type suspension has a number more components that can go wrong. I've driven it for a while and it's the one thing that feels sort of wrong with the car. The box is probably going bad, and that's a couple hundred to replace(Assuming I would use an aftermarket or quicker ratio box), as are all the arms and linkages. Yes it would still be cheaper to replace it, but not enough cheaper to warrant doing when I plan on swapping eventually anyways, if that makes any sense.

When I said 50/50, I really meant that as a goal, and I meant that I intend to go ls or at the very least, something aluminum (and set back a little), and that, as well as the tubular crossmember, tubular arms, and removing the weight of the steering box and ac, will put me much closer to that goal 50/50 than the factory weight distribution.

Thanks for the information!!

Want_a_v8

Hey man, thanks for the help. I've been through that thread, and I've even watched most of his youtube videos as well.

I originally thought this was going to be my route, but sadly, due to the FD rule book, If I ever want to compete in pro am or anything further, Doing so would make me ineligible. According to the rules, the original suspension style must remain, so in this case, the McPherson strut style must remain. Steering style and arms and whatnot is perfectly ok to mess with, but suspension types? No game. I looked into setups like those from an 240sx, or an e36 bmw, but none are even close to the same width and whatnot of the F-body platform. Due to these rules, I'm not even technically allowed to use 4th gen style suspension.

That car is gorgeous though!

Thanks!

1986BANDIT

there are a few drift third gens on you-tube,have a look at what they did and it may help guide you down the path you seek.

McLovin1181

I'm honestly don't see the benefit of a rack in comparison to how much work it would be to get one to not feel like garbage.
If your goal is very fast sensitive steering, you can achieve that with the stock setup.
I have new linkage,shaft,and a RedHead 12.7 box and it has ZERO play and is incredibly sensitive.
I have no problems getting through even Miata sized slaloms.
The instructions at my local AutoX club said it was the tightest worm steering they'd encountered.
And a few of those members are several time SCCA national champions.

And if you want to go even further, Turn-One offers F-body boxes down to 8:1 ratio if you have the guts.