Rear Springs

[Reddragon]

Ladies and Gentlemen

From some of the pictures that were supplied in the rear disc and panhard bar discussions it got me to thinking.

Went to a friends place a couple saturdays ago to dismount the springs on the front struts to prepare them for making them into coil over with the Miata kit. Also had a set of stock rear Miata coil over that a friend gave me, so disassembled them too. The shocks are shot but wanted the springs to experiment with.

Now these springs have a 3 1/4" inside diameter, that matches what the top perch on the TR7 for the stock springs is with out the rubber isolater in place. If the rubber was trimmed it could still be used.

Now the stock Miata springs are rated at 98 lb with a progression to 550 as they compress. It is from a web site and I take everything with a grain of salt.

In the coil over kits the springs are 400 and 300 rated, plan to use the 300 on the front.

Now the questions, are the ones going to the rear coil overs for the TR7 for better control, or because of the unavailablity of better spring rates? Does it matter if that the springs are in front of the axel or are the coil overs more precise in controling the action of the rear end?

I ask these questions to see if making a bottom perch for an upgrade set of Miata springs in place of the stock ones is worth the effort.

The plan for my FHC is to drive it and occassionally autocross it.

Thanks for your insite.

Dale
1974 TR6
1977 TR7 FHC

[V8Wedgehead]

Reddragon-
The placement of the rear spring in the stock location or as a coil over assembly will work either way. You can change the bottom perch anything can be welded! If you remove the some rubber at the top of the spring mount I would advise you to put a metal strap across the spring area that would hold the spring in place and centered. This wil keep it from falling off of the perch when completly extended. I dont think you want to use a 300lb spring in the front or the rear unless it is for competition. On the street it will ride like a concrete truck with a full load. Woody at the wedge shop has coil over kits for the front and some radical but very functional rear suspension setups......www.thewedgeshop.com. Good luck.

Michael
1980 TR8 FHC/Works Rally Project

If it is broken then fix it....if it is not then make it faster!"

[Beans]

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Reddragon</i>

...Now the questions, are the ones going to the rear coil overs for the TR7 for better control, or because of the unavailablity of better spring rates? ...<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">
I am going for coil overs at the rear for three reasons;
<ul><li> Better availability of springs;</li>
<li> Better quality dampers;</li><li>combined with decent mounts it will (slightly) improve axle location.</li></ul>Bear in mind though that I have access to some pretty good local and friendly motorsport firms who take pride in making one off's [:)]

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">
...Does it matter if that the springs are in front of the axel or are the coil overs more precise in controling the action of the rear end?<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">
Location of the springs on the lower link has an effect on the (effective) spring rate. Everything to do with the length of the lever arm.
As an example a 200lbs spring on the standard location will have an effective spring rate of approximately 160lbs. Moving the spring backwards onto the axle will increase the effective spring rate.

<center>
<font color="blue"><i>1981 TR7 FHC Sprint (better known as 't Kreng)
1981 TR7 DHC (not very well known yet, but back on the road)
Also a 1980 TR7 DHC, 1980 TR7 DHC FI, 1981 TR7 FHC</font id="blue">
<font color="red">http://tr7beans.blogspot.com/</i></font id="red"></center>

[tr8]

Here is the rear coil over set up on my TR7 race car. It was built by a BL dealer back in 1980 and he told me that the rear suspension set up was directly from BL and that he had a proper engineering drawing for the set up.

Paul

[tr8]

The shocks and springs are Carrera, which are now called QA1.

Paul

[Reddragon]

V8Wedgehead

The top spring perch without the rubber isolate in place has a 1/2" retaining circle in place. The Miata spring inside diameter (3 1/4") fits with in the stock spring perch retaining area.

Are you suggesting that the retaining area be increased in size / length and if so what would you suggest the add amount be?

TR8

The coil overs you have, can they be set up as a street application or are they a race only item?

Thanks for your help and advice.

Dale
1974 TR6
1977 TR7 FHC