front inboard mounted shocks

olskoolsi

olskoolsi

Member
I was just wondering if anybody knows a good source of info for building a good working inboard mounted shock system. I was looking at the factory five coupe that is designed with this system and it looks fairly straight forward. I plan on using a modified mII front end by eliminating the spring towers and using modified tubular a arms.

any help much appreciated
 
This kit is a must have piece for MRC owners that are running CVD style front axles. Whether you are running the stock chassis or the DarkSoul chassis,
 
olskoolsi said:
I was just wondering if anybody knows a good source of info for building a good working inboard mounted shock system. I was looking at the factory five coupe that is designed with this system and it looks fairly straight forward. I plan on using a modified mII front end by eliminating the spring towers and using modified tubular a arms.

any help much appreciated
Click to expand...

I interject here only to clarify: do you actually mean inboard shocks AND

springs?
 
Bgbkwndo said:
I interject here only to clarify: do you actually mean inboard shocks AND

springs?
Click to expand...

Opps! Good question. I made the mistake of assuming (yeah, I know...) that he meant both, as in coil overs. Sorry about that. :eek:

Just re-read his post, and it does mention removing spring towers, so maybe...
 
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If you happen to click on the link in post #3...and you are contemplating duplicating that rather cool looking front suspension...don't!

There is an obvious geometry error there...anyone spot it?
 
Re Geometry: I looks to me like they were trying to replicate a strut rod arragngent like an MII had with the A arms. During the suspension travel it looks like the rear facing A arms will pull the wheels back instead of them moving straight up and down. This will lilkey result in changing caster and toe in.
PS: I don't pretend to be an expert in suspention geometry or design
 
thanks for the replies guys. i have an idea of copying yhe factory five racing's coupe where the rocker going to the inboeard coilovers (i mentioned coilovers because i didn't mention that in my first post) is built into the upper a arm. it looks simple enough to do and and the stock geometry of the mII set up would be retained, i'm assuming this, but i don't see how it would change. I don't have acad right now so i really can't draw something up to show you guys, i'm just hoping my explanation makes a clear enough picture..

sorry to change the subject here but does anybody have or has used the acad inventor program. from what i can understand is that you draw something out like a front suspension etc etc and actually work it through its range of operation to see if there are any flaws. anybody

thanks
 
Ken47 said:
Re Geometry: I looks to me like they were trying to replicate a strut rod arragngent like an MII had with the A arms. During the suspension travel it looks like the rear facing A arms will pull the wheels back instead of them moving straight up and down. This will lilkey result in changing caster and toe in.
PS: I don't pretend to be an expert in suspention geometry or design
Click to expand...

You're on the right track. Those front wheels will barely move up and down at all. Only within the limits of the elasticity (flexibility) of the bushings.

The two arcs described by the outer ends of the front and rear of each of the a arms are completely different. They only coincide right where the wheel sits. Anywhere else and something has to give. I would say the travel at the wheel wouldn't exceed maybe 1 1/2". They cannot go either backwards or forwards, but you had the right idea.

The mounting points at the frame MUST be perfectly in line with each other, ie you should be able to pass a dead straight rod directly through the bushings. Those guys are out something like 45º. The car was built that way many years ago, and frankly, I'm sort of surprised they didn't fix it when it was all redone. Perhaps they don't know...??? :confused:

Look at ANY other IFS setup, and the bushings will always be 100% in line with each other...guaranteed.
 
yes i see what your saying, this is why (for my first attampt at this) i intend to use the stock positions of the a arms and just modify some tubular a arms to suit. seems simple enough to do
 
Just because you see a car in a car show or read about in a magazine doesn`t mean its safe or the system will even work .One must use a little common sense.This suspension is pretty wild and extremly loaded .The coil (overs) required here must withstand pressures of 2000-3000 lbs per side. The shock part will have trouble keeping the coil stable during the control arm travel .You don`t want the travel to be any more than half an inch due to bump steer.This system would be anything but safe due to many factors ,but it shore looks pretty and people do like looking at the unusual.Remember here it`s your life in your design.


Bob
 
34ford said:
Just because you see a car in a car show or read about in a magazine doesn`t mean its safe or the system will even work .One must use a little common sense.This suspension is pretty wild and extremly loaded .The coil (overs) required here must withstand pressures of 2000-3000 lbs per side. The shock part will have trouble keeping the coil stable during the control arm travel .You don`t want the travel to be any more than half an inch due to bump steer.This system would be anything but safe due to many factors ,but it shore looks pretty and people do like looking at the unusual.Remember here it`s your life in your design.


Bob
Click to expand...

You make an excellent point about it being safe, or even working.

I am of the opinion that if you are going to build a car of this nature, then everything should at least be properly functional.

This suspension can easily be made to work correctly, and with very minor modification the coil/shocks would work as well.

I don't know if you are familiar with the engine in this one, but it was originally built by Mickey Thompson, one of a pair. The car has been reported as being "scary fast" and I don't doubt it, especially the scary part.
 
olskoolsi said:
yes i see what your saying, this is why (for my first attampt at this) i intend to use the stock positions of the a arms and just modify some tubular a arms to suit. seems simple enough to do
Click to expand...

I answered 34ford's post before yours for a reason. So you can check that just for reference.

There's nothing wrong with doing what you plan to do. That's what I did on the front of my T-bucket many years ago. All you need to do is to make sure you keep the stock distances when you do the mods. As for spring rates and shocks, the weight of your vehicle as compared to the original can be used as a good guide.

If your car is going to be a similar weight to the original M2, then the original spring rate will be close. Heavier - or lighter - it will need some sort of adjustment either way. If I haven't explained that very well, rattle my cage and I'll try again.
 
cocobolo said:
You're on the right track. Those front wheels will barely move up and down at all. Only within the limits of the elasticity (flexibility) of the bushings.

The two arcs described by the outer ends of the front and rear of each of the a arms are completely different. They only coincide right where the wheel sits. Anywhere else and something has to give. I would say the travel at the wheel wouldn't exceed maybe 1 1/2". They cannot go either backwards or forwards, but you had the right idea.

The mounting points at the frame MUST be perfectly in line with each other, ie you should be able to pass a dead straight rod directly through the bushings. Those guys are out something like 45º. The car was built that way many years ago, and frankly, I'm sort of surprised they didn't fix it when it was all redone. Perhaps they don't know...??? :confused:

Look at ANY other IFS setup, and the bushings will always be 100% in line with each other...guaranteed.
Click to expand...

They are proabably trying to get away with it by using spherical rod ends that have some forgiveness. What I noticed in his front suspension is that all the rods seem to be parallel. When you move the coilovers inboard, you use a bellcrank to transfer the force through a rod to the A arm. It still has to have some angle down to work. The less angle, the more stress on the suspension and the higher the spring rate.

Russ
 
wrascal said:
They are proabably trying to get away with it by using spherical rod ends that have some forgiveness. What I noticed in his front suspension is that all the rods seem to be parallel. When you move the coilovers inboard, you use a bellcrank to transfer the force through a rod to the A arm. It still has to have some angle down to work. The less angle, the more stress on the suspension and the higher the spring rate.

Russ
Click to expand...

Yep, that's exactly right. His bellcrank is very short on the upper side, which gives it very little travel.

You are also right in saying that this would equate to requiring a stiff spring and shock. The lower (horizontal) arm of the bellcrank is much longer, which in turn means that in this case the actual movement on those springs is essentially nothing. But there isn't much movement regardless of that, by virtue of the incorrect design of the a arms.
 
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