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Location:
Adelaide
Registered:
October 2002
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KE10 - KP61 front end conversion
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Thu, 21 July 2005 23:11
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For all the suspension/steering gurus out there, I understand that if I was to do a rack and pinion steering conversion, the inner ball joints should rotate around the same axis as the lower control arms ie pivot from the same spot when the wheels are in a straight line, but what I dont understand is why when I measured up my ke10 last night, I discovered that the steering arms actually pivot closer together than the lower control arms. From memory its about 2cm shorter either side, wouldnt this cause bump steer? Or would it have been designed like this at the factory taking into account the effects of other things, and they were actually made to pivot differently for a reason?
Will it be a problem if i make mine pivot inline, the way it should be? or is that bad?
Stewart, your a gun at this kind of stuff. any ideas?? Im looking at doing a ke20 front end conversion and using a rack & pinion and crossmember out of a KP61. That could be hard though considering ive never seen one in Australia..
That brings me to my next question, Anyone know where I could locate a complete KP61 front end in Australia?
Cheers, Nathan
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Location:
New Zealand
Registered:
May 2002
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Re: KE10 - KP61 front end conversion
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Thu, 21 July 2005 23:20
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Chances of finding KP6* crossmember in Australia = "Slim" to "Can I have some of those really good drugs you are obviously smoking if you think you can find one?"
Realistically you simply won't find one, freight from NZ would be pricey too. Have you got measurements of what you need? I could check the chassis rail spacing on my car if you want.
Callum
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Location:
Adelaide
Registered:
October 2002
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Re: KE10 - KP61 front end conversion
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Thu, 21 July 2005 23:27
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yeah, that'd be pro. Thanks mate. If you could measure the chassis rail bolt spacing (probably around 28") then the bolt spacing on the same rail. Also the distance between both inner pivots on the steering rack.
Cheers.
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Location:
New Zealand
Registered:
May 2002
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Re: KE10 - KP61 front end conversion
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Thu, 21 July 2005 23:43
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Unfortunately I can only get the chassis measurements from mine, running TA63 crossmember and rack. Know a few people who should be able to measure up their cars though. Will get back to you tomorrow after I pick up my car from the sandblasters.
Callum
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: KE10 - KP61 front end conversion
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Fri, 22 July 2005 06:21
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| ke1500 wrote on Fri, 22 July 2005 09:11 |
For all the suspension/steering gurus out there, I understand that if I was to do a rack and pinion steering conversion, the inner ball joints should rotate around the same axis as the lower control arms ie pivot from the same spot when the wheels are in a straight line, but what I dont understand is why when I measured up my ke10 last night, I discovered that the steering arms actually pivot closer together than the lower control arms. From memory its about 2cm shorter either side, wouldnt this cause bump steer? Or would it have been designed like this at the factory taking into account the effects of other things, and they were actually made to pivot differently for a reason?
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well.. if you look at the steering arms, the tie rod end actually sits inboard of the strut pivot.. by maybe 2cm 
| Quote: |
Stewart, your a gun at this kind of stuff. any ideas?? Im looking at doing a ke20 front end conversion and using a rack & pinion and crossmember out of a KP61. That could be hard though considering ive never seen one in Australia..
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aww shucks 
yar, hard to come by in aus, and parts would cost a bomb to import.. although if you had the steering rack, you can pretty much bodge up everything else... use a KE70 steering column maybe?
k.. what IS important is that the length of the tie rod is the same as the length of the lower control arm.. and that, when viewed from the front of the car, the arm and tie rod are parallel. if they are also parallel viewed from the top. there can be no bump steer, regardless of where the actiual pivot points are.
BUT, you want ackermann angles, so to do this, you move the steering rack behind the steering arm pivots, and lengthen the tie rods a bit..
this is where it gets tricky... you have a trade off between position of rack, length of tie rod, change in effective width of tie rod with suspension travel etc...
ideally you would just copy the whole lot, and keep all the original points in the same position (including wheeelbase and track)
anyhoo, a few thoughts... it aint simple and you neeed to think in 3D for both ssuspension movement and steering input... not easy for old brains but it is just a mathematical problem..
Cya, Stewart
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Location:
Adelaide
Registered:
October 2002
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Re: KE10 - KP61 front end conversion
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Fri, 22 July 2005 06:50
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Righto then.
This is what i know:
1. Steering arms to be be parallel when looking from in front of the car.
2. Steering arms to be parallel from when looking from above the car.
3. steering arms and lower control arms to be the same width centre to centre.
I understand the steering arms and the lower control arms are to be of an identical length, centre to centre. With this in mind, is the reason the factory KE10 inner tierods are 2cm further inwards (towards the centre of the car), because the tierods at the steering arms are actually offset 2cm inwards as well? - for ackerman angles?
So to the un-educated person having a quick look, it doesnt look like it all lines up but when you actually take it apart and measured it precisely, you'd find the steering and lower control arm lengths are the same?
This means i could take a steering rack out of a falcon who's inner tie rods would pivot heaps far apart, but so long as i kept the steering arms the same offset (on the strut), it should still work? - providing i can keep everything inline when looking from in front and above.
And, is the reason the KE10 tierods are offset (ie. all pivots are 2cm inwards compared to the control arm pivots) for ackerman angle reasons? which i have no idea about...?
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Location:
Adelaide
Registered:
October 2002
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Re: KE10 - KP61 front end conversion
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Fri, 22 July 2005 06:56
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Righto then.
This is what i know:
1. Steering arms to be be parallel when looking from in front of the car.
2. Steering arms to be parallel from when looking from above the car.
3. steering arms and lower control arms to be the same width centre to centre.
I understand the steering arms and the lower control arms are to be of an identical length, centre to centre. With this in mind, is the reason the factory KE10 inner tierods are 2cm further inwards (towards the centre of the car), because the tierods at the steering arms are actually offset 2cm inwards as well? - for ackerman angles?
So to the un-educated person having a quick look, it doesnt look like it all lines up but when you actually take it apart and measured it precisely, you'd find the steering and lower control arm lengths are the same?
This means i could take a steering rack out of a falcon who's inner tie rods would pivot heaps far apart, but so long as i kept the steering arms the same offset (on the strut), it should still work? - providing i can keep everything inline when looking from in front and above.
And, is the reason the KE10 tierods are offset (ie. all pivots are 2cm inwards compared to the control arm pivots) for ackerman angle reasons? which i have no idea about...?
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: KE10 - KP61 front end conversion
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Fri, 22 July 2005 07:29
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for reducing bump-steer with suspension movement, looking from front of car, lower control arm and tie-rod are to be parallel, and lower control arm and tie rods should be same length.
for zero ackermanm when steering, when looking from the top, the tie rod and the control arm should also be parallel.
in reality, the steering back will be a bit further back toward the rear of the car, and so the tie rods will be a little longer.... but the pivot points will be in the same place.. sorta.. well.. just imagine the tie rods are rubbery, and you pull the steering rack backwards.. the only pivot points to have changed are the end of the steering rack and they only move backwards..
this way, you don't change bump steer, you get ackermann angles, but as for ackermann AND suspension movement.. that'll take more thinking..
for KE10.
the steering arm/tie-rod pivots are inboard as they would hit the tyre otherwise. to compensate for this, the pivot at the other end of the tie rod is also inboard a bit. so thas on a dise to side basis...
ackermann is a front to rear offset of the inner tie-rod pivot points... (get some bardboard and make some models and mvoe them around.. it helps a lot with your understanding..)
the KE10 gemoetry is far from ideal tho... in fact it's shite.. the drag link moves up as well as sideways and it's all terrible but seems to vaguely work a bit..
to change R&P into KE10, i would..
-make tie rods the same length as the lower control arms (regardless if you keeep the A-arm or move to a KE20 type).
- then, position the tie rods (when looking from front of car) to be parallel to the low arms (we are always talking abotu the straight line between pivot points.. regardless of the shap of things)
- then, i eould position the rack a bit behind the line between the steering arm pivot points to give ackermann.. how much is a guessing game, but i would look at other cars to get an idea. sayy, KE70 to start.
so now thats all lined up, i would measure the distance required between the inner tie rod ends, and then start looking for a rack...
when fitting rack to car i would initially allow some adjustment forwards and backwards to change the ackermann angles (and would check by both driving and measurement.,. taking into account desired slip angles etc)
but once the position is decided, make proper solid mounts that can't move..
another problem with KLE10 struts is that they do not pivot around the center of the strut axis, as later KE's tend to do... they have a more complex geometry with an offset pivot point (i think the pivot point is outboard of the strut axis) so that you have more complex changes in geometry than normal..
initially (after a very short think) i think this is done to reduce scrub radius and turning effort, and i think it may also reduce the camber change for a given steering input... altho that can always be exacerbated bu using more castor...
still with me? i think a few bits of balsa and some real life models would help a lot... although measurement and replication is always a difficulty..
anyways, good luck 
if you find the length of the KP61 steerign rack, please let me know..
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Location:
New Zealand
Registered:
May 2002
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Re: KE10 - KP61 front end conversion
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Fri, 22 July 2005 10:25
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http://www.1uzfe.com/
Look at the steering stuff here, ended up using an MR2 rack which is around 2 inches wider.
Callum
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: KE10 - KP61 front end conversion
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Fri, 22 July 2005 11:11
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looking at his geometry (just from the pics) i would not feel safe in that car.. then again, he also wants to do high speed with buggerall suspension movement in a light car with heavy engine..
if you are expecting no suspension movement (and not expecting to turn), steering geometry gets a whole lot easier
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Location:
New Zealand
Registered:
May 2002
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Re: KE10 - KP61 front end conversion
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Sun, 24 July 2005 08:21
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Got those measurements. 
Front bolt holes - 730mm ish
Rear bolt holes - 720mm ish
Front to rear - 86mm ish
All measurements centre to centre. Can't remember what the KE1* setup is, but Starlet uses the sway bay for fore-aft location rather than castor arms. No measurements on the swaybar mounts, mine have been cut off.
Callum
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: KE10 - KP61 front end conversion
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Sun, 24 July 2005 20:31
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ke10 rails are 28" apart (710mm?) and 10cm between bolts.
KE10 uses A-arm techanology and no swaybar or rdius (castor) rod.
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Location:
Adelaide
Registered:
October 2002
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Re: KE10 - KP61 front end conversion
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Sun, 24 July 2005 23:04
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Thanks for that, As confusing as it may be! I'll work something out. Anything can be done with enough effort!
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Location:
Adelaide
Registered:
October 2002
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Re: KE10 - KP61 front end conversion
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Tue, 26 July 2005 04:00
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I like how you call it A arm 'Technology' 
With the kingpin location on the KE10 strut, Its actually better as the wheel rotates near the centre of the tire rather than towards the centre of the car more. And seeing as though im running 17's now, tire to guard clearance when on full lock will actually be better as it wont hit the bottom front of the guard near the apron. Which may be a problem. This is why im going to keep the KE10 strut, and so that my wheels are still the correct offset. Now all i need to do is find a steering rack which inner tie rod ends are no more than 48ish mm apart, Convert the lower control arms (providing theyre the same length as KE10) to KE20 an make up some rose jointed radius rods to hold it all together.
Any ideas??? Im thinking Upullit's a winner.
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Location:
Adelaide
Registered:
October 2002
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Re: KE10 - KP61 front end conversion
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Tue, 02 August 2005 04:30
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Next question:
If by moving the crossmember forward a centimetre or so to improve castor, Would this have the same effect as re-drilling the Kingpin & altering the inclination, or would it also improve static castor? Are there any pro's & cons?
According to the KE10 owners manual, they come standard with 7deg kingpin angle? does that equate to 7deg castor?
Would it be bad for me to swap my steering arms over so that the tie rods are now in front of the crossmember? - allowing me to mount the rack in front of the crossmember? It'd obviously have a negative effect on the castor, but maybe if i had the steering arms welded and re-drilled?
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