Rear suspension

[Grabber70Mach 107]

So trying to figure out what is the best way to go in my situation.  Getting back to working on my 70 Mach 1, lots has been planned and many parts already purchased.  I'm looking at doing a minitub on it and am swaying towards the MTF tubs.  Looked at the DS tubs and Dynacorn tubs but don't really want to deal with interior mods.  

I already have the SorT coilover kit for the front and rear.  Years ago I purchased the Vintage Venom Cobra brake kit and installed it.  That's where I'm hoping to get some advice from someone that may know or can give me better advice then my thinking.

 

In the rear the Vintage Venom kit uses a bracket for the caliper and a hubcentric spacer that moves the wheel out approximately 7/16".  The MTF mimitubs give around 2" more of width in the wheelwell, if I understand correctly. (Has anyone done these on a 69-70 that would share some pictures? If so there appears to be a section towards the front that the tub doesn't sit flush with the rail.  What is the measurement from the rail to the inner edge of the tub in that area?).  So the SorT rear kit I purchased you weld the brackets on your rear housing.  Figured since I have the rear out I'm thinking about narrowing it to get my 7/16" back on each side.  Well you know what happens when car guys start thinking.  Now I'm debating if I should just go down to the width of a 65-66 rear.

 

65-66  57.25"

           58.375" If I remove 7/16" per side for a total of ⅞".              

69-70  59.25"

 

I assume this rear measurement is housing flange to housing flange.  Is that correct?

 

In the attached pictures it shows currently how the car sits.  The rear tires are:

 

Rims: 17x10.5 

Back Spacing: 6.8" (174mm) 

Offset: +28mm (1.10")

Tires 315/35/17's

 

I'm staying with this size tire at minimum, but will explore going wider if I can.  I've also thought about calling Quick Performance and just getting them to do a new housing for me.  If I go with the 65-66 width, will my axles work as they are?  Can I just have them shortened and resplined if needed? They are  31 spline axles.

[RPM 1,190]

Grabber, I always liked the look of your Mach 1. I've never fit 315/35/17's on my 69, so I lack that fit knowledge.

Yes, I believe the correct way to measure axle housing width is outside flange O.D. 

I'm pretty sure you can shorten the axle at the splines without issue. 

Why do you need a narrower rear housing and wheel house work done? Is the tire rubbing on the wheel opening lip? Any chance you're using wheel spacers you can eliminate? I pounded out the spare tire indentation on the right rear inner wheel house for more clearance on my 69.

I'd think the least expensive option would be to narrow your housing ~1 inch per side and cut the axles. 

 

[Grabber70Mach 107]

Thanks.  Right now I'm running a leaf spring setup, 5- leaf mid-eyes.  I'm installing the SorT coilover 3-link setup.  I am running a 7/16" spacer that has to be used with the Vintage Venom brake setup.  I'd like to get the rear a tad lower and would feel comfortable with a little more wiggle room.  This is why I'm wanting to do the MTF mimitubs and thinking about narrowing the rear.  If that gives me the ability to run a wider tire than that's a bonus.  I've even thought about doing a slight Trans-am flare on the rear if needed.

[mustangstofear 608]

I constantly get asked how big a tire can I run with our mini tubs and keep the leaf springs. The answer is you won't gain anything,  the leaf springs hinder you from going wider. Using a standard 52 inch 65-66 housing will only give you a deeper dish wheel.

[Grabber70Mach 107]

33 minutes ago, mustangstofear said:

I constantly get asked how big a tire can I run with our mini tubs and keep the leaf springs. The answer is you won't gain anything,  the leaf springs hinder you from going wider. Using a standard 52 inch 65-66 housing will only give you a deeper dish wheel.

I'm ditching the leaf springs and installing a SorT coilover 3-link that is patiently waiting in the garage.

[Phils69 27]

Thanks Grabber. Life gets in the way but its time I get back on it. Do you have a link to a pic of the suspension kit you are going to use on a 69? My friend is helping me with mine and he is the brains of the outfit as far as suspension goes lol. He is a racer from way back. He is retired now and builds high end cars frame up. I have sent him links on the kits out there I thought looked good but he didn't like the geometry . He buys a lot of frames and stuff from a company call Art Morrision, man they are nice. They don't have a four link kit for my car but we are going to get their generic kit and adapt it. Thats the plan at least. Have to make those floor pan rails and get them installed first.

[Grabber70Mach 107]

Hello Phil I'm working on a 70 but 69/70 are basically the same suspension wise.

Here's a link to the suspension I'm using:

http://www.streetortrack.com/Street-or-Track-Rear-Bilstein-3-Link-Coilover-System-pr-24572.html

[SM69Mach 68]

19 hours ago, Grabber70Mach said:

Hello Phil I'm working on a 70 but 69/70 are basically the same suspension wise.

Here's a link to the suspension I'm using:

http://www.streetortrack.com/Street-or-Track-Rear-Bilstein-3-Link-Coilover-System-pr-24572.html

Would love to do this upgrade one day.  Keep us updated once you get it installed and on the road.  

[Phils69 27]

Looks like a really nice and complete kit. Looking forward to the pics.

[Phils69 27]

I see its compatable with a rear exhaust too. That looks like its going to be a challenge with any coilover system in our cars. Going to be fun lol 

[buening 63]

Excellent choice on the suspension upgrades!  Some day I hope to do the same.  As you know we have twin cars with the same wheel and tire package.  I've been mulling the MTF minitub as well but may just pie-cut and reweld the area where the tire rubs on the front inside wheelwell to get me by until the suspension upgrades.  Keep us in the loop on how the install goes!

 

Regarding the 7/16" for Vintage Venom, one thing you may consider is swapping out the VV bracket and spacer for the Mustang Steve brackets. Those have a 2 piece offset caliper bracket, which avoids the need for the 7/16" spacer for caliper alignment. You'd be $200 into those brackets, which has got to be easier than shortening your axles and tubes (plus pulling all of that and getting it to a shop).

[Grabber70Mach 107]

Thanks Buening (Jay?).  That is something to consider with the Mustang Steve brackets.  Only thing I'd have to get shortened on mine is the housing if I only do 1/2" on each side to bring it back to stock width within 1/16" on each side or basically 1/8" narrower than stock.  Axles would remain the same. 

[fvike 173]

This is my car  mounted on 315/30/19s. Borrowed wheels, so I don't remember the BS or width on the rims. No tubs, original, but modified wheel houses.

The car is not on  the ground here, but there was a wee bit clearence. When the car sat on the ground, the wheel moved outward, and the clearing was incresed. Rolled freely.

 

The modifications done to the wheelhouse is a wedge laid into the front of the wheel house. They are very narrow in the front, but are plenty big enough otherwise. The best thing about this mod is that it does not move the brackets for the rear fold down seat or interior panels. The rear seat mount is welded because my car had them offset to one side. No gap between the panel and seat on one side, and 1/2" gap on the other. You can se the top slide lock has not been touched.

Edit: Rear seatbelt anchor is still in place between the wheelhouse and frame rail. Will have to go if you tub it all the way.

Panel mount is untouched.

 

This picture shows how narrow the front of the wheel house is. There is plent of space towards the frame rail.

 

 

[mustangstofear 608]

On 8/5/2020 at 2:29 AM, Phils69 said:

I see its compatable with a rear exhaust too. That looks like its going to be a challenge with any coilover system in our cars. Going to be fun lol 

We make tailpipes that will go around any system out there.

[jeff69 10]

Those MTF tubs look like something you'd see in a Pro-Street car from the 90's. I was under the impression that any mini tubs would require interior mods. Check out Detroit Speeds wheel tubs.

[mustangstofear 608]

the reason we sell so many mini tubs compared to our competitors,  is because you can still use your original interior. I wished I  had a dollar for ever customer who calls me complaining about the DSE tubs they installed , and now they have to have custom interior made.