McLaren replica build base on a Manta

[Matthew]

Hi there! Really nice work Terry I always loved those cars..
I would like to make myself chassis for the Mirage but I am just starting in kit-cars. Does someone have any drawings of the chassis, frames etc. and exact dimensions of the Mirage chassis and parts? I would be really grateful if someone could send them to me. Waiting for answers on PM.

Matthew

 

Very nice work..later Luke

 

[Terry Oxandale]

Mathew,

I've drawn plans on what I'm doing more keep me from doing, redoing, redoing again during the fabrication stage. Below is an example of a drawing that has a lot of the dimensions of the OEM Mirage framing. If this looks like it would help, let me know. I'ts only a drawing and not any of the cool CAD (or similar) programs.

ox

 

[David Sturch]

Terry and Matt,
I am going to post the drawing I have also, so that anyone else that needs it can access it. Leon is also doing an M6GT so between the three of you can figure out the diamensions. This drawing is set up for transverse engine mounting.
Dave

 

[Matthew]

Terry, David,

thank you very much for the drawings, they would be great help for me. But could you give me a favour Terry and could you upload the picture in higher resolution? It's because I can hardly see the dimensions variables on the drawing.. hope that I can start my project soon. Thanks a lot and keep on working.

Matthew

 

[Thomas]

Terry,

Nice build. Will like to see it when you are done.


tm

 

[Terry Oxandale]

So would I! I finally got to a stopping point on the front suspension. I had to change plans on positioning the 911 rack under the C4 steering arms (where the taper is for the tie-rod ends). I realized I needed to raise the rack and instead mount it on top of the C4 steering arms. So I milled the tapered bore out off-axis from the original axis, inserted DOM tubing into the new bore, and clamped everything togther with some bolts that were obviously too long.

This shows the new angle of the mounting bolt for the rod end. Prior to boring this hole off-axis, the Heim at static ride height was at it max angle.

Everything in postion (somewhat), and ready to go to the rear suspension for a few months. Yes, this photo was taken prior to reboring the C4 steering arms. This also shows the 4" extenders I had to fabricate in order to get the rack to an acceptable length to reduce bumpsteer.

 

[Jac Mac]

Your not finished yet, you need a longer rack & shorter extenders.

 

[Jac Mac]

The yellow dots show approx where the pivot points are on top/bottom W/Bones and where I reckon the rack ends & outer rod ends pivots should be to minimise bump steer.

 

[egoman/ Shawn Wedge]

I agree with jac mac the way that it currently sits your bump steer will be terrible.
You lined up the suspension pivots with the rack ends but you forgot to place the entire assembly in a parralellagram state. Actually the problem could also stem from the position of the steering arm relaytive to the spindle. I am used to the dirt track stuff where we try for 0 ackerman.

 

[Terry Oxandale]

Dang Jac Mac. Your word carries a lot of weight for me from reading your contributions, so I'm puzzled because multiple references indicate that the inner pivot should be on a line connecting the inner pivots between the upper and lower arms (but obviously I cannot align the outter ends with the balljoints), and the extended centerline of the steering rod should also intersect the same point that the extended centerlines of the upper and lower control arms meet e.g. instant center (roughly on the opposite side of the car near the lower balljoint location in my case). See below.

I guess I'll need to do a little more work here (scratching head).

Thanks for the input,

ox

 

[Jac Mac]

Pic modded.
You need a longer rack- mounted slightly higher by the look of it. Its the amount of ackerman built into the C4 uprights steering arm thats leading you astray. ( Be nice if they had built them with a bit less for our purposes). While you could simply extend the rack, that would leave it unsupported further outside the housing and increase the likelihood of bending it under high loads. The steering arm ball joint dimension outboard of the line drawn thru top/bottom ball joints is essentially what the rack needs to be lengthened by on both ends them adjust either the rack height or the tie rod end height to fine tune..

actually if you remove the coil from the LH shock and keep reducing the length of the tie rod until you get minimal bump steer thru vertical susp movement, then turn the rack until the LHF is straight ahead with what you have there will give a fairly good idea of rack length increase reqd.

 

[Terry Oxandale]

Thanks for the tips and knowledge. So, I went out and "sighted" the angle change as I moved the suspension through about 4" of travel (had to let the spring all the way down), and as you said, it was obviously "out". It appeared to increase the toe-in (viewed with an attached rod against a reference line on the floor) as I raised the axle. So I raised the rack by 25mm and re-measured. I found I'd slightly overcompensated, so I stuck 3mm of shim under the outer joint, and as it stands, there is no perceptable "visual" indication of any angle change through 4" of travel. Yes, I'll need to measure this more accurately later, but it appears you've helped me to at least get it fairly close.

The rack gear is pretty stout (25mm thick), so I don't think I'm going to risk anything by making new longer pieces later.

ox

 

[David Sturch]

Terry,
Maybe you should try the original rack that you had in the first pic's you posted. It look's like a Pinto or Escort rack. It would give you the lenght you need. The rack you are using now look's a little Monoposto to me.
Dave

 

[Terry Oxandale]

The original rack was toast (torn boots, sloppy joints, etc). I did ask about the Pinto/Mustang II racks, but they were still 2 inches too short verses the 4.5" needed on the 911 rack, and their design did not lend well to modifications to the ends of the rack to futher increase the length. So until I find something I like better, I'll keep looking. Thanks for the tip

I hope you're fairing as well as can be expected (A-tomic). I heard some discouraging news on NPR today in regards to the Canadian GM situation. I hope things are working well for you given the situation.

ox

 

[David Sturch]

Terry,
I was down to the plant I used to work in. It was Oshawa Truck. They closed it today. They ran 40 truck's off the line and raffled of a nice GM Sierra for Sick Childrens Hospital in Toronto. They raised $93,000.00 CDN for the Hospital. I did not win it of course. It was a good place to work and we built a good product and won many JDPower awards. Most of the work gone to Mexico. My pension check are still going in but for how long who knows will have to wait and see.
As for your rack I have an escort rack and Russell K is also using one and he had his lengthened for his M8 this would work for you also. There are two types, one has a longer pinion shaft than the other. I got mine off e-bay for US $25.00. A MkI or II should work.
Dave

 

[Jack]

Ox,
I've got a rack from a TVR 280I. I'll measure end to end for you. It's yours if it will work.

 

[Terry Oxandale]

Jack,Dave,

I appreciate that. I've looked up some ebay items, and will go to the "yard" tomorrow bright and early and measure a few on the cars to see what the rack-end configurations look like. if its a tapped hole, thumbs up, if not, go on to next option. You've got to have a real passion for this to go on the cheap like this, or a desire for self punishment.

 

[David Sturch]

Terry,
The rack I found was a remanufactured unit with a TRW Rack and Pinion. The price was right. Now that I have the Lathe I can make up the rod end adjuster's. I will be running pins in the steering arms. Jack's TVR rack would be a Triumph rack most likely.
Dave
Here is a Delco pic of mine.

 

[Terry Oxandale]

Dave, can you provide a part number or year application?

Thanks.