Board logo

Top rear wishbone probelms - MX5 Haynes Roadster - newbie
Zyme - 31/7/16 at 03:58 PM

Hello I've been "building" an mx5 haynes roadster for a few months now and I've run into several problems. I thought it was about time I joined the community to see if I can help figuring out what to do.

Okay so a while ago I got a MX5 donor and managed to acquire a chassis that was based off the saturn design that accommodates the MX5 running gear. I became a bit enthusiastic buying lots of parts. I knew I needed wishbones at some point, so being naive I went ahead and bought the some talon TMXR mx5 wishbones. At the time I thought that because they were designed to fit the MX5 hubs and the Haynes Roadster that they must fit.

Well as it turns out they do fit, except for the rear top two wishbones. Obviously I know now that the talon chassis design changes how the differential is mounted allowing the top rear wishbone to be longer. Hindsight is a wonderful thing, perhaps I shouldn't have rushed to buy things.


[img] rear top wishbone 1
rear top wishbone 1 [/img]

[img] rear top wishbone 2
rear top wishbone 2 [/img]

[img] rear top wishbone 3
rear top wishbone 3 [/img]

So what should I do?

Should I try to modify them by cutting them back, making a jig and then re-welding them so they are shorter?

Or not bother and just buy a pair of top rear wishbones that match the saturn pdf design?

Slimy38 - 31/7/16 at 04:23 PM

If memory serves, the Saturn wishbones move the adjusters to the bottom wishbones. If you simply replace the top ones with a Saturn design, you're not going to be able to adjust camber or toe. You either need both Talon or both Saturn.

I'd maybe go for modifying those ones, but it'll need a bit of thought to keep adjustment and positioning on what will be a much shorter wishbone. And a means of attaching the suspension upright as well.

Talon Motorsport - 31/7/16 at 04:53 PM

As you don't have the top brackets welded on I'd make the top wishbones a short H pattern with adjusters on one end.

Zyme - 31/7/16 at 09:33 PM 

code:
As you don't have the top brackets welded on I'd make the top wishbones a short H pattern with adjusters on one end.


The top brackets are already welded onto the chassis. I would need to cut them off and replace them then? Also what about the position of the top suspension bracket? that's also welded in place.

Also would this work? It's kind of a H shape that way I could keep the outer adjusters. Apologies for the crude drawing.
[img] wishbone changes
wishbone changes [/img]

Thanks

Talon Motorsport - 1/8/16 at 07:40 AM

I would say start again with new top wishbones but then I sell parts so I would say that..........
I am making a batch of TMXR wishbones over the next two weeks I'll see if I can find the SSC plans to work out the bracket spacing. Converting the TMXR top wishbones to the SSC plans is some thing I've been meaning to do for a while but then I have lots of plans and no time/money to do any of them!

Slimy38 - 1/8/16 at 07:52 AM

quote:
Originally posted by Talon Motorsport
I would say start again with new top wishbones but then I sell parts so I would say that..........
I am making a batch of TMXR wishbones over the next two weeks I'll see if I can find the SSC plans to work out the bracket spacing. Converting the TMXR top wishbones to the SSC plans is some thing I've been meaning to do for a while but then I have lots of plans and no time/money to do any of them!


I posted them here if you need them;

http://slimyroadster.blogspot.co.uk/2013/07/mx5-plans.html

But there are several key measurements missing, most importantly from your point of view the overall length of the top wishbones is absent.

Zyme - 1/8/16 at 10:48 AM

quote:

But there are several key measurements missing, most importantly from your point of view the overall length of the top wishbones is absent.


I found the missing measurements thanks to talon on the haynes forum.

https://haynes.co.uk/forums/showthread.php?t=13104

http://s812.photobucket.com/user/talonmotorsport/media/RearUppers_Page_1.jpg.html



quote:
Originally posted by Talon Motorsport
I would say start again with new top wishbones but then I sell parts so I would say that..........
I am making a batch of TMXR wishbones over the next two weeks I'll see if I can find the SSC plans to work out the bracket spacing. Converting the TMXR top wishbones to the SSC plans is some thing I've been meaning to do for a while but then I have lots of plans and no time/money to do any of them!


Do you think you would be able to make a top pair of saturn wishbones but with adjusters on the inside? Or a pair of shorter TMXR with the adjusters on the outside? If so what kind of price would they be? thanks

Zyme - 11/8/16 at 09:50 PM

do you think this would work for the top?

mx5 top rear wishbone
mx5 top rear wishbone

mx5 top rear wishbones
mx5 top rear wishbones

Nimmo - 1/3/18 at 11:07 AM

hi there i know its been a while but how did you get on with these rear top whishbones I like that drawing you did on the last post?