MX5 Donor, Using as a Donor/problems/solutions/advice Info

[PorkChop]

Originally Posted by vmax1974

What size and grade bolts have people used to hang the diff

Need to know before going and ordering my nut and bolt set

Using the saturn plans and want to get the diff mocked up this week

Dunno about size, but you'll want 8.8 grade at the very least.

[PorkChop]

Originally Posted by shh120m

Solution to steering rack clearance issue. Turned alluminium tapered insert fitted into control arm on upright reamed to take standard ford rs2000 track rod ends from the top as opposed to underneath. Picture taken without rack in place but gives an idea how much clearance there is now. Its yet to be seen if there is any significant change to the amount of bump steer as the instant centre position is changed from the original setup, but either way its safer than having contact between rack and wishbone. I did toy with the idea of changing the upper wishbone to induce some negative castor, both to help lift the control arms and help with self centering, but it would be no consellation to those who have already made their wishbones so i think this is the best solution, although iirc talon was talking about using the bent bmw track rod ends- thats another solution well worth playing with, i dont know if hes tried it might be worth a mention.

David bolam was asking about wingstays, if you make them like mine, just be sure to make sure the return angle at the bottom clears the wishbone plates at full hight of travel otherwise if there is any interference it could cause an accident whilst flying over the brow of a hill not being able to steer, probably best to use the dust cover holes as mounting points as suggested, something i never thought of duh

Just to add to this; I've been researching both locostusa and Keith Tanner's build site.

The vast majority of people Stateside have had issues with the track rods fouling the lower wishbone. There are several reported ways of tackling this...

1 - straighten the steering arm so that it's horizontal, then ream to take a TRE from the top. Don't like the idea of this as you'll probably have to heat the arm, so the upright could be fatigued as a result of this.

2 - a mark 2 MX5 upright has raised steering arms compared to the mark 1 (7mm difference). The TRE would fit as OEM. There should be enough adjustment in the steering design to remove any bump steer that this might dial in. The 7mm may be enough to provide sufficient clearance. This is how Keith Tanner did it after trying rose joints on mark 1 uprights.

3 - remodel the front edge of the lower wishbone to clear the steering rack completely. This is how it is on a MX5.

Looking at the way Nathan has done it, I would be tempted to try a MX5 TRE instead of a Ford item in that situation. The cranked end of the TRE would bring the track rod down a bit, should still provide sufficient clearance for the lower wishbone and might reduce the amount of bump steer introduced by doing this.

Here's an article I found on bump steer - http://www.longacreracing.com/articles/art.asp?ARTID=13

Any thoughts?

[vmax1974]

Originally Posted by Talonmotorsport

Can I ask how you are planning to mount the diff?

Same way as the donor bolt through the mounts then rigidly mount the doughnut rubber to a plate welded to the diff cage

Then I was thinking about solid mounting the diff nose to take the place of the ppf on the donor was also going to work out a shield to protect me should the diff break

[Talonmotorsport]

Have you thought about making a bracket out of some 5mm plate that looks like this at all? Remove all the blocks/brackets around the nose fit some 3/4-19mm round stock with 12mm through holes in the 18-19mm holes in the nose and use M12 bolts.

[vmax1974]

That was the kind of thing I had in mind

Was worried about vibration from the diff till I remembered the book build diff is hard mounted to the chassis

[Talonmotorsport]

Originally Posted by PorkChop

Just to add to this; I've been researching both locostusa and Keith Tanner's build site.

The vast majority of people Stateside have had issues with the track rods fouling the lower wishbone. There are several reported ways of tackling this...

1 - straighten the steering arm so that it's horizontal, then ream to take a TRE from the top. Don't like the idea of this as you'll probably have to heat the arm, so the upright could be fatigued as a result of this.

2 - a mark 2 MX5 upright has raised steering arms compared to the mark 1 (7mm difference). The TRE would fit as OEM. There should be enough adjustment in the steering design to remove any bump steer that this might dial in. The 7mm may be enough to provide sufficient clearance. This is how Keith Tanner did it after trying rose joints on mark 1 uprights.

3 - remodel the front edge of the lower wishbone to clear the steering rack completely. This is how it is on a MX5.

Looking at the way Nathan has done it, I would be tempted to try a MX5 TRE instead of a Ford item in that situation. The cranked end of the TRE would bring the track rod down a bit, should still provide sufficient clearance for the lower wishbone and might reduce the amount of bump steer introduced by doing this.

Here's an article I found on bump steer - http://www.longacreracing.com/articles/art.asp?ARTID=13

Any thoughts?

That seems like an a lot of machine work for a home builder to do why not just make the whole thing more simple like this:

[PorkChop]

So there is an option 3 available ; my problem is I've already got the front wishbones to SSC spec.

[Talonmotorsport]

I really don't like the SSC front lower wishbone design it realise on people's ability to weld those adjusters a little too much for my liking, they make the wishbones overly complicated with no apparent need for them as there is an adjustable drag link at the top.

[Davidbolam]

I've got the ssc ones and there is no fouling of the wishbones and steering arms. I have put a limit on the amount of lock available but there is still more than my passat has.

David

[PorkChop]

Originally Posted by Davidbolam

I've got the ssc ones and there is no fouling of the wishbones and steering arms. I have put a limit on the amount of lock available but there is still more than my passat has.

David

How much lock did you take off David (how thick were your stops?).