Bump steer after aw11 manual rack conversion

Nomnom83
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Bump steer after aw11 manual rack conversion

Postby Nomnom83 » Wed Jun 29, 2016 10:10 pm

Installed and centered aw11 manual in my ae86, now have bump steer when hitting bumps on the passenger wheel. Anyone else have this issue?

Found this
http://forums.club4ag.com/zerothread?id=89702&page=2

But no one else talks about this.

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davew7
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Re: Bump steer after aw11 manual rack conversion

Postby davew7 » Thu Jun 30, 2016 4:07 am

If you are "sure" that the inner tie rod pivots for LH/RH are equal distance, [not clamped in AW-11 factory location] then you will have to adjust the elevation at each pivot point to get ends of the tie rods traveling thru the same arc.
Get a suspension handling book that shows how to make a simple dump steering gauge, and plan on several hours making shims to get the minimum bump steer. You will find that an adjustment as small as .020" will change the steering. You can also adjust the fore/aft location of the rack, but that will also affect Ackermann. Dave W

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Re: Bump steer after aw11 manual rack conversion

Postby Deuce Cam » Thu Jun 30, 2016 2:02 pm

I remember the thread/pic you linked and it's the only place I've seen the comparison. I asked around a lot over the years and nobody seems to know for sure if they are different.

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ToeKnee805
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Re: Bump steer after aw11 manual rack conversion

Postby ToeKnee805 » Thu Jul 07, 2016 12:53 am

track driving i felt like the ae86 rack was harder to turn than an aw11 rack, but as far as bump steer, do you have RCAs already? Maybe converting to manual just made the bumpsteer that was already there more noticeable?
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Deuce Cam
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Re: Bump steer after aw11 manual rack conversion

Postby Deuce Cam » Tue Jul 12, 2016 11:47 am

I just came across this pic in badboy88000's build thread (ae86 top, aw11 bottom):

Image

The ae86 housing definitely is shorter. I wonder if the rack/gear is the same length since it's hard to tell in the pic.

Also, here's the pic from Grant's old build thread that the op linked (ae86 on top, aw11 bottom):

Image

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Re: Bump steer after aw11 manual rack conversion

Postby assassin10000 » Thu Aug 04, 2016 2:11 pm

Yeah, both housings are different lengths. Aw11 internal gear is about 1/8" longer than ae86.

Andrew

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Re: Bump steer after aw11 manual rack conversion

Postby Deuce Cam » Thu Aug 04, 2016 3:33 pm

Assuming the r&p are interchangeable... the quaife aw11 r&p (or stock aw11) in an ae86 housing might be ideal.

I wonder how the ae71 stuff compares.

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Re: Bump steer after aw11 manual rack conversion

Postby Deuce Cam » Sat Sep 16, 2017 2:37 pm

So an opportunity presented itself to measure an ae86 rack/housing and an aw11 rack/housing.

The housing AND rack are different lengths when comparing the ae86, and aw11 parts. I used a measuring tape with the racks both installed on different cars, so the measurements aren't exactly precise, but anyway here goes:

ae86
rack: 21-11/16"
housing: 15-3/4"

aw11
rack: 21-7/8"
housing: 16-3/8"

The aw11 housing is 5/8" longer than ae86. The distance between the middle of the driver side mounting point and the end of the driver side rack housing is the same on both. This means the extra 5/8" length on the aw11 housing all ends up on the passenger side when installed in an ae86. In other words, an aw11 rack housing is off center when installed in an ae86.

It's also interesting to note that the ae86 rack length (part that inner tie rods bolt to) is 3/16" shorter compared to the aw11 rack. The increased length equates to higher steering ratio AND steering angle/travel. Think of the added length like a rack spacer which also adds more angle/travel.

For reference I also found this old link: http://www.ae86drivingclub.com.au/forum ... -2778.html

The most important post from the linked thread above is quoted below for convenience:

2nd March 2009, 08:28 PM
Note: still looking for info if you have it, but below is what I think from limited info, but cafefull measuring and calculating of what I do have:


All manual racks (except aftermarket quick racks) use the same pinion (6 teeth) and gear ratio. (About 43.3mm rack movement per turn). All rack housings (at least the manuals) are of the same width, 400mm +-1mm.

AE86/AE85 with power steer
rack width: 530mm?
stroke: 130mm
turns: 3

AE86/AE85 with manual steer
rack width: 552mm
stroke: 152mm
turns: 3.5

AE86 GTV manual
rack width: 530mm
stroke: 130mm
turns: 3

The GTV has the same steering rack ratio, but the resulting steering is quicker only due to the shorter power steering knuckles. Due to the sharper angle the PS knuckles would give, the GTV rack stroke is limited. Both the regular manual cars and the GTV would have similar maximum steering angle.

KE70/AE71 some* manual
rack width: 545mm
stroke: 144mm
turns: 3.3

*The KE70 in Australia shares the same rack housing as the AE86 (400mm wide) and the same pinion and gear ratio, but the rack itself is not as long. Some KE70's in other countrys use the same rack as the AE86.

To achive the sharpest steering angle with the above parts, we use the longer 152mm steering rack (not the GTV one), combined with the PS/GTV knuckles. At this point, the tyre may start to rub on the inner body. To achive even greater steering angle (with either **longer rack, special rack ends, slip on spacers or screw on spacers) you also need longer lower control arms.

Tie-rod ends:
AE86 steering rod ends are about 190-195mm long, from ball joint centre to end. Due to a narrower rack, the GTV ones are about 208mm long. With longer lower control arms, use RA40/KE30 tie-rods.

Quick racks from TRD, Cusco/Chowini and Quaife are all based on the normal 152mm stroke manual rack. The Quaife one is still available, and has 2.5 turns.

**If you want a custom length rack, you can use a RA60 one and cut it down.
Kid Karola


The specs listed in the above quote for ae86 are in line with my measurement.

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Re: Bump steer after aw11 manual rack conversion

Postby Deuce Cam » Thu Sep 21, 2017 12:20 pm

Also reached out to quaife regarding their qsr kits for ae86 and aw11. Both kits use the same exact rack. Only the pinions differ. Both racks are 21.653" long, which is even shorter than an oem ae86 manual rack

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Re: Bump steer after aw11 manual rack conversion

Postby xslowpokex » Fri Sep 22, 2017 4:32 am

If your 86 is lowered more than 1.5inches from stock you will need front RCAs to alleviate the bump steer, if you have RCAs and your bump steer is still persistent then your car is too lowered. You have 3 option, go back to powered steering, raise your car up, or just live with it. I honestly think manual steering is more adequate in a track or weekend car its very inconvenient for daily driving especially in tight spaces, like parking lots, parallel parking, moving in slow traffic, its just a work out period lol and if not done right can actually make the steering feel crappy leaving you with too much steering slack to sort out. But deleting the power steering does make for more noticeably rev happy 4ag : )

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Re: Bump steer after aw11 manual rack conversion

Postby BattleGarage_RS » Fri Sep 22, 2017 1:46 pm

I strongly urge people to find a true manual rack because of the bump steer we noticed with the AW11 racks when properly centering the rack.

Your choices with the AW11 rack seem to be 1. Have too much angle turning left 2. Having equal steering angle but worse bump steer on oneside than the other.

Also, hit up Ezekiel for a proper P/S rack de-power service. I have driven his car multiple times with his properly de-powered rack and it feels GOOD!

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Re: Bump steer after aw11 manual rack conversion

Postby Deuce Cam » Fri Sep 22, 2017 3:29 pm

^exactly. Equal steering from center (lock-to-lock) when using an aw11 rack in an ae86 equates to different overall tie rod lengths (inner pivot to outer pivot) on each side, which causes the alignment/bump steer issues.

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Re: Bump steer after aw11 manual rack conversion

Postby zokustyle » Wed Nov 15, 2017 12:48 pm

Other than finding a factory manual steering at a junkyard (impossible now?), where are we supposed to find an AE86 manual rack? Everyone has discontinued their remans.

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Re: Bump steer after aw11 manual rack conversion

Postby GZE_RA21 » Tue Nov 21, 2017 3:14 pm

^^^^Have you tried rockauto.com? Last I checked they still had manual racks.


*edit just checked, they are in fact out of stock currently. :(

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Jeonsah
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Re: Bump steer after aw11 manual rack conversion

Postby Jeonsah » Mon Dec 18, 2017 7:48 am

When shopping for a AE86 manual rack online, what information should you provide? Didnt manual racks sometimes come on 87 GTS/SR5 Models and thats it? When I use that info on RockAuto, I see FX16 FWD racks that are manual.. Does anyone know if those are compatable?

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Re: Bump steer after aw11 manual rack conversion

Postby CloudStrife » Mon Dec 18, 2017 9:36 am

Listen to Dave, he knows what he is talking about. If you have bumpsteer issues, they can be corrected. Doing the manual rack conversion has to be done professionally.

You will not be able to find a manual rack through any of the US parts stores. The supplies are exhausted. I extensively searched for them before deciding on the AW11 swap. I went to Autoz, Oreilys, etc. etc., found part numbers, called the manufacture directly (I.E. A1 cardone or whatever other BS refab company, which is the same trash suppliers RockAu uses), and they said they weren't even available to order. The problem is, is that all of those companies are refab. They don't actually make racks, brakes, etc. They wait for a core and refresh them. If no cores come in.. no refabs come out :)

Even if they did become available, they'd be so far on back-order you'd be like 15th in line lol.

Now if there was another chassis you could swap from that would be a different story.
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Re: Bump steer after aw11 manual rack conversion

Postby Jeonsah » Mon Dec 18, 2017 2:29 pm

davew7 wrote:If you are "sure" that the inner tie rod pivots for LH/RH are equal distance, [not clamped in AW-11 factory location] then you will have to adjust the elevation at each pivot point to get ends of the tie rods traveling thru the same arc.


Can you elaborate on this? I am confused on "pivot points" and equal distance. With an AW11 rack, are you saying that the inner tie rod pivots are not in the same height/plane as the LCA pivot point (the part where it bolts to the car)?

I am running a AW11 manual rack. When I installed the rack, I centered the rack by using a tape measure. I push the rack gear all the way out until it hit the inner tie rod. I then divided that distance by two and that was were I set my center. Now when I turn the steering wheel, there are exactly the same amount of turns from left to right.

Also - I have a full coilover setup with the bump steer outer tie rods from T3. They lower the outer tie rod connecting point on the knuckle. This makes the tie rods in the same plane as the LCA. So when the LCA moves in an arc during suspension travel, the tie rods are in the same plane/arc. Isnt that all you need to care about when it comes to bump steer?

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Re: Bump steer after aw11 manual rack conversion

Postby Deuce Cam » Mon Dec 18, 2017 4:37 pm

Think about the housing (part thats fixed to x member). Aw11 is 5/8" longer than ae86. That extra housing length all ends up on passenger side when installed on ae86, so its off centered. The inner tie rods limit the racks travel by contacting the housing. Think about it:

BattleGarage_RS wrote:Your choices with the AW11 rack seem to be 1. Have too much angle turning left 2. Having equal steering angle but worse bump steer on oneside than the other.


Jeonsah, if you have equal steering travel side-to-side with your setup it basically means the overall length of your tie rods (inner and outer) is different on each side. This is what causes the bump steer when using using an aw11 rack - and centering it - on an ae86.

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Jeonsah
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Re: Bump steer after aw11 manual rack conversion

Postby Jeonsah » Tue Dec 19, 2017 11:53 am

I understand.

Quick question. Assuming this is the correct way to depower a power steering rack:

http://www.86garage.com/forums/viewtopi ... =17&t=2822

1. Are there any steering rack spacer options for the power steering rack? Since the MR2 rack allows for more steering angle, if I swapped back to a depowered ps rack, I would like to have the same angle.

2. How do aftermarket tie rods reduce bump steer? I am referring to the tie rods that have the spacers between the knuckle and the tie rod heim joint:

https://technotoytuning.com/sites/defau ... k=PqwXpFR0

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Re: Bump steer after aw11 manual rack conversion

Postby zokustyle » Tue Dec 19, 2017 2:26 pm

As far as the spacers that go between the tie rod and knuckle, you're just able to further correct geometry with the suspension and steering that wasn't corrected with an RCA.

I've been doing more reading on de-powering the power rack and am interested but also curious about angle difference like Jeonsah. I don't know an exact difference in angle between manual and PS racks but I do know the Battle Version or AJPS rack spacers on a de-powered PS rack should net you as much as an AW11 rack, without the AW11 issues. The BV kit isn't available anymore but the AJPS offering is pretty much the same. Here's info from an old BV kit post:

This kit is specifically designed to fit either an 85 power steering rack with pump removed and no fluid, or a non power rack with non power knuckles. That being said, there are a few reasons for this. Kit #2 includes an actual extension piece and a stopper to fit on the left (passenger) side of the rack along with a 5mm spacer for the right (driver) side of the car. By adding an extension, it allows you to get 20mm overall length to the center section of the rack which dramatically increases angle. Almost 20 degrees more which is about the same as replacing your rack with a non power unit. The reason why it will only fit the 85 power rack is because that rack has more teeth machined into the center shaft then the 86/87 models. You have to understand that you cannot run power steering if you have this spacer on. It is because by adding that much length, the end of the shaft will go into a pressurized area of the rack and leak very badly. This isn't much of a problem for most who have done motor swaps as they have already taken there power steering pumps off. This kit is a very inexpensive way to get the angle that a non power rack has without having to replace the rack unit itself.

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Jeonsah
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Re: Bump steer after aw11 manual rack conversion

Postby Jeonsah » Wed Dec 20, 2017 6:41 am

Here is what a bump steer gauge looks like:

http://www.jegs.com/i/Longacre-Racing/4 ... gKoy_D_BwE


Basically this measures the toe change as the suspension travels up and down. So by adding spacers to the outer tie rod, you are changing where in the arc the tie rod is at. At the end of the day you are making the rate of arc change between the LCA and outer tie rod minimal. So then when your suspension travels up and down, the toe change of the wheel is less. Using the gauge you can add in certain size shims to the outer tie rod to dial it in. I would say adding shims to the outer tie rods would be for fine tuning of the bump steer. However, using a longer AW11 housing would possibly require a bigger fix (described later down below). Here is a generic video that will show the concept:

https://www.youtube.com/watch?v=Stp9kHAGfXQ


I think a super simple easy fix for AW11 Steering racks would be to have a 5/8" spacer on the driver side of the steering rack. The spacer would be the same size as an inner tie rod stop. This would push the driver side inner tie rod pivot point out further to match the passenger side. Opinions on this?

Something else to remember is that bump steer will never be removed completely. There will always be some but it can be tuned out to be hardly noticeable.

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Re: Bump steer after aw11 manual rack conversion

Postby Deuce Cam » Wed Dec 20, 2017 8:44 pm

The idea of after market tie rods correcting bump steer, more specifically the spacers that go between the rod ends and knuckle, is a bit of a gimmick on an ae86. Its because of the 86's spindle/steering knuckle layout... if one uses an rca, the control arm and tie rod are spaced down equally to help correct geometry, which is good. Further spacing on the tie rods isnt needed, and 'could' have a negative affect. Sure one could forego an rca and just space down the tie rod ends, but then the lca and tie rods will be less parallel in relation to one another.

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