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View Full Version : MN12 vs. SN95 shocks



Mercutio
01-03-2008, 05:44 PM
Does anyone know if the front shock bodies for an MN12 are the same outer diameter as the front struts for an SN95? I ask because if they are, I'd like to try out a Maximum Motorsports coilover kit for the SN95 (available for Bilstein and Koni/Tokico strut bodies. If the threaded sleeve that surrounds the strut body will fit snugly on our shocks, I should be able to make the rest work. And before I drop $260 on the conversion kit I figured I'd ask here first.

I already have a set of GP coilovers from a year or two back, but I've come to the conclusion they're not the hot setup for autocrossing. Still, I'd like to be able to play with spring rates, and that means coilovers would be great...

Mike8675309
01-03-2008, 09:25 PM
Are not the SN95 cars actual struts?

This link seems to give some hope to a swap. I would expect you'll have to check dimensions to make sure it'll fit.
http://www.sn95brakes.com/lincoln_mark_vii.php

Mercutio
01-03-2008, 09:41 PM
I'm not sure we're on the same wavelength--the link you post is about putting SN95 brakes on a Lincoln Mark VII (Fox body) and I don't think it applies to my question. I wish to use MN12 shocks on a MN12. However, I want to use a threaded spring perch as seen in this link:

http://www.maximummotorsports.com/store/index.php?main_page=product_info&cPath=2_78&products_id=279

The threaded tube slides over the shock body, but as this kit is designed to fit the struts on an SN95, I need to know whether an SN95's front struts and an MN12's front shocks share an identical outside diameter.

Or I guess I could just ask: if anyone has a set of MN12 Koni, Tokico or Bilstein shocks sitting around, could you please measure their diameter for me? Same goes for a set of SN95 struts from the same manufacturers.

XR7 Dave
01-03-2008, 11:16 PM
I think what you will run into is that the stock MN12 shocks have spring perches already welded to them fairly high up on the shock. Perhaps it would work ok to cut down the perches shown for that kit but then the question would be if the springs would fit in the remaining space. I'll look, I have some old shocks laying around.

Mercutio
01-03-2008, 11:40 PM
True, but perhaps I can use a spring with a shorter free length. As long as I don't get into coil bind before I hit the bumpstop that should work, I think.

XxSlowpokexX
01-03-2008, 11:53 PM
I have sn95 front struts/coil overs on my fox body cougar..From the looks of it..Its far from any type of even semi direct bolt on..E

Ddubb
01-03-2008, 11:56 PM
I have a shock for a 96/97 Sport Tbird ..

Shock Body upper half
1.8" Dia.

Shock body lower half ( welded right above spring perch )
1.9" Dia.

Spring rubber insolator inner diameter
@ 3.54"

Plastic sleeve at top of shock ( can be removed )
3.1" Dia.

- Dan

seawalkersee
01-04-2008, 12:01 AM
Also, the strut bearing/mount for the top of the strut is larger than that of the bird/cougar. You will have to get new mounts, and I dont know what size they are, or how many bolts they have.

Chris

Mercutio
01-04-2008, 12:07 AM
So long as I can get the threaded sleeve over the shock body I should be able to use the stock upper mounts in conjunction with the parts that came with my GP QA1 coilovers--I think.

Thanks for the measurement, Ddubb.

Mike8675309
01-05-2008, 11:58 AM
Sorry, thought it was MarkVIII

If you can get it to fit, you may be able to fab something up. You will want to keep in mind that some shocks have had issues on the MN12 platform with bending lower mounts. That tells me if you fab something up, you need to make sure it is stout.

Mercutio
01-11-2008, 08:28 PM
Okay, here's what I've found out so far. I have an old set of Bilsteins that are 1.975 diameter; I measured a set of stock shocks at 1.920. I ordered a set of Bilstein 2-in ID, 7-in length threaded sleeves that fit the shocks perfectly. Tomorrow I'll test fit them to check the little stuff like hardware and all that. 10 or 12-in coilover springs should be about the right length. If all this stuff fits I'll post up some pics and a list of part numbers as a new thread in case anyone else is interested in trying it. If this works out it should make it easier to fine-tune handling, ride height and shave a few pounds off the nose of the car.

XxSlowpokexX
01-11-2008, 10:15 PM
there is already a coil over option out for the mn12 platform. If this is a cheaper alternative however Im sure people will jump on it

They have a coil over kit for irs equiped cobras that should fit in the rear but may interfere with tire clearence. from what I understand the rear shocks are intrchangable between the irs cobra and the sc

Mercutio
01-11-2008, 11:04 PM
I'm assuming the existing coilover option you refer to is the QA1 coilover group buy from a few years ago. If I'm wrong, and there's another source I don't know about, let me know. I got in on that group purchase, but I've come to the conclusion it's not working out for the autocrossing I do with the car. I just don't think the QA1 shocks are as good or valved as properly for what I want to do as a Koni or Bilstein. I know at least one MN12 drag racer with a very fast car removed his as well. I'm sure the option has worked out for some, but more options are always good.

I'm aware of the Cobra rear coilover setup, and I'm curious about it, but I'm hesitant to try it for several reasons. The first is tire clearance. The second is whether the coil would fit properly around the upper shock mount on the body. The third and most important consideration is whether the shock mount on the lower A-arm is strong enough to support the weight of the car. And then of course there's the cost in case it doesn't work.

Ddubb
01-12-2008, 12:45 PM
I wouldnt put a coil spring around the factory shock in its location for the reasons you mentioned.
If I were to do a Coilover shock combo on the Tbird rear IRS, I would probably start with a pair of Mark 8 control arms and make a custom perch for the shock / spring to mount to. Then cut the upper spring bumpstop and fab a bracket or modify it so the shock can be used.

The spring shock combination I will be using is the convertible 03 Cobra Bilstein rear shock, and front Sport shocks along with SC/Sport springs .. problem Im having right now is all of the weight I removed from the car and engine bay, plus the aluminum block explorer engine makes the front end sit quite a bit higher. So an adjustable spring height with an adjustable spring rate might be something that would help out for me as well.

- Dan

Mercutio
01-12-2008, 04:35 PM
Okay I just tested this out and it works, but there is a but. That but is that making it work requires the upper spring mount from the GP coilover, which was machined to work in conjunction with the stock Tbird upper spring mount. Standard coilover mounts are different, so to make this work, people will have to make a custom upper spring mount. I'll get to work on some pictures, but I'm kinda sick today so after I got this done I just hit the couch and haven't moved since.

seawalkersee
01-13-2008, 03:09 AM
Im egarly waiting.

Chris

Mercutio
01-13-2008, 10:20 AM
Okay, here we go.

Here are the components you'll need: a set of front shocks, the coilover sleeves, a set of springs (these are 12-inch long, 2.5-ID QA1s), the machined top mount and a set of Torrington bearings. The Torrington bearings aren't necessary, but they do make it much easier to tighten the coilovers. For what they cost they're definitely worth it.
http://i241.photobucket.com/albums/ff99/featheredmafia/MN12%20coilovers/DSC_3756.jpg

The top mount is the only real snag in this project. On the left of this picture is the top mount that came with the Bilstein coilover sleeve. On the right is the top mount from the group purchase a year or so back that's machined to fit our existing spring/shock top mount.
http://i241.photobucket.com/albums/ff99/featheredmafia/MN12%20coilovers/DSC_3764.jpg

The coilover sleeve (part number at summit racing is BSN-B4BOA0000117) mounts to the shock exactly as our lower spring mount does. However, the outer diameter of the shock body is really critical. This Bilstein shock body measured 1.975 inches, and the mounting ridge is 2.100 inches. The ID of the sleeve is 2.00 inches. A very little slop in the size of the shock body can make a lot of trouble here. Example: whatever the donor shocks are for the Konis on my SC measured 1.920 in diameter. While .08 inch doesn't sound like much, remember that the mounting ridge is only 1.00 inch! So now you're counting on .01 inch of contact per side between the sleeve and the mounting ridge. How brave are you?
http://i241.photobucket.com/albums/ff99/featheredmafia/MN12%20coilovers/DSC_3759.jpg
http://i241.photobucket.com/albums/ff99/featheredmafia/MN12%20coilovers/DSC_3758.jpg

But here's how it looks when installed.
http://i241.photobucket.com/albums/ff99/featheredmafia/MN12%20coilovers/DSC_3755.jpg

I loaned my racing scales to a friend this weekend, so I wasn't able to measure the difference in weight between a stock set of springs and the smaller coilover springs. I'm guessing perhaps 7.5-10 pounds, something like that. Hypercoil has a new OBD spring that's designed for lighter weight that might be a good option. This installation is shown on my LX because I had to harvest the top mounts from that car. This year I plan to try autocrossing the SC with this coilover setup and as I do so I'll update how effective this setup is. The first event of the year is a National Tour on 2/23, so I'll report on that. Any questions?

seawalkersee
01-13-2008, 11:18 AM
Wonder if we can just get in touch with QA1 and see if they can stop their machine from cutting off that much material. I would think if they could make a run of 100 or so that it would be worth it.

Chris