Using Mcpherson Spindle in SLA setup

[Dannyho]

I'm looking to build a custom, ***read: budget*** suspension in a classic mopar. I'm throwing around ideas of what to grab for a donor, but the only SLA suspensions that i'd like to use are corvettes and vipers. and while corvettes are easier to find, it's still a little pricey. since it might be easier to find a mcpherson style spindle that would meet my requirements for king pin angle and such, is it just a matter of machining the upper pivot to accept a ball joint? or does anyone else have any ideas, i understand that it might come down to me ahving to bite the bullet and do it corvette, but i'd just like to know my options

 

[GregLocock]

To be honest I can't quite see what your idea is. Are you proposing to unbolt the shock from the knuckle and put in a dummy shock with an upper pivot?

Your list of acceptable donors looks a bit odd, more driven by fashion than function!



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[Dannyho]

basically what I want to do is to replace the stock spindle, brakes, and everything with one thats more updated and has better geometry. I'd have to fibricate my own upper and Lower A arms and design for their mounting points, but I'd like to know if its possible to machine the top mounting point, where the strut attaches normally, to accept a standard ball joint that I will have installed in a custom upper A arm. this is totally disrgarding the shock placement in my car. that will be determined after everything is set up. This would be a less espensive way to get a little more performance and disc brakes on a 70's muscle car. and to my knowledge i don't know what other cars out on the roads right now, use a short- long arm suspension other than viper and corvette that still have acceptable geometries for a sports car design, but if you know something I dont, please let me know

 

[GregLocock]

Crown Vic. Lincoln LS.

I still don't understand your original idea. Can you draw it and post it somewhere?

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[Dannyho]

unforuntately I'm a terrible artist, but I dont know any other way to put it. I'd just liek to know if it's possible to use a front spindle, including hub, brakes, calipers and make it work with double A-arms even though originally it used a mcpherson strut type suspension. The more I think about it, the more i think it's possible but not easy, and i might end up getting my hands on a hub for real cheap, and just trying it out.

 

[modesign]

The use of a strut hub with a ball joint fitting is used on many 'kit' cars to make a cheap twin link suspension. Typically UK spec Ford parts. The fittings range from a turned alloy top fitting to a welded part. As the KPI of a strut conversion is based on the origional strut fitting which in turn has to have spring etc clearance it may need modification. This can be incorporated into the ball joint conversion. Remember that you cannot use the standard bottom ball joint as it is not designed for the load from a spring/damper unit.Another type must be fitted.
Regards,
Sandy Cormack

 

[NormPeterson]

Remember that you cannot use the standard bottom ball joint as it is not designed for the load from a spring/damper unit.Another type must be fitted.

That depends on the car that donated the knuckle. The Fox/SN95/miscellaneous related Ford control arm and balljoint carry the vertical loading already, as the spring for those cars is located midway along the control arm rather than being concentric with the strut itself.

Conversions such as Factory Five [Cobra replica company in Wareham, MA USA] use these pieces instead of borrowing from a pure MacPherson Strut. FWIW, there's at least one such strut to SLA conversion that's been modified for less KPI then OE rather than the greater KPI that usually results. I think it's more like 10* instead of 15-ish OE and 20* in the basic SLA conversion.

Norm

 

[GregLocock]

OK, 1/3 of the way down this page on the left is what I think you are talking about:

http://www.miracerros.com/mustang/t_suspension.htm

If you like the KPI/camber/scrub radius that that setup gives you then fine, but it looks to me as though the KPI is greater than you'd get in a properly designed short spindle SLA.




Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[pmwltd]

I have converted two different cars with strut front suspension to
SLA. Both of them happento be front wheel drive, however the principle is the same with rear wheel drive and a little less crowded.

The CRX we did had an upper mount welded onto the upright, the VW Rabbit had a bolt on upper mount. This was a racing application, so the pickup points were spherical bearings and rod ends.

You can see pictures of this on the web site in the gallery.

http://www.pmwltd.com

Hope this is of some help.


Dave

 

[Dannyho]

i've actually come across your site before. How did your setups end up in geometry as far as king pin inclination, caster and such? were you able to machine the upper mount in a way to improve everything or were you locked into the design given to you by honda or VW. I've been looking into this and i have been discouraged by the original specs of the hubs themselves. I imagine it would be possible to fabricate something, especially since i plan on using an 18 inch rim and would have some leeway there. but how was your experience?

thanks for your input!
Dan

 

[pmwltd]

With the front drive setup we had to minimize scrub radius, so we ended up with a KPI of just under 12 deg. With rear drive, you caould design in more scrub radius and less KPI. We ran caster in the 4 to 6 deg. range, which was adjustable by moving the upper AArm, for and aft. The camber curve was adjustable by moving the upper AArm pickup points up and down, in the range of ratio from a low of .6 to a high of 1. This does cause some problems maintainimg a good RC, and FVIC, without also changing the lower pickup points also.

The CRX was A GT4- GT5 car in SCCA road racing, and the Rabbit was an E- Prepared car running in solo events. So the setups were somewhat different.

Regards

Dave

 

[DaCudaKid]

Danny,

I think I understand what you are trying to accomplish. I'm new on this forum so I hope I don't break any rules here. There are two companies that I have used for parts and/or info for projects like yours,

http://www.magnumforce.com

and

http://www.racefabinc.com.

Both companies are great and have lots of experience and inf avalable. 'm sure you'll find all of your answers at those two places.

Mike, a life long Mopar Man

http://www.tipmaster.com/images/thumbsup2.gif