dickruzzindesign@aol.com

Hi Dick
Just wondered if you could help. Do you know of any supplier in the US who has made a stronger steering rack for a Mangusta. I race my Mangusta and the Renault Four rack, A is not up to the job with sticky race tyres and B the ratio is so bad that if the car brakes away in a corner it takes forever to wind the steering back to correct. Let me know if you can help.
Kink regards
Mike Eagles email mike.fairmont@gmail.com

MIKE,
No-one would make aftermarket parts for a market of 401 cars. The Mustang rack is available easily in racing catalogs. I would check there.
DICK RUZZIN

Hi Dick, a previous owner of 1302 was a highly respected race chassis/ exhaust engineer. He calculated swept ratios etc and came up with replacing the front callipers with Volvo 246Gt callipers. These originally were a 2 hose connection in Volvos, however they were drilled through for a single connection hose setup. Only other change is mounting plate and kept original Girling callipers. Resulting difference from original is chalk and cheese with fronts just locking marginally before rears under heavy braking. Overall I feel it is a well balanced system and I am running EBC Red pads all around.
Thanks Mike

Whatever works. That was a lot of work and expense.
Adding an adjustable proportioning valve keeps the car original and allows you to fine tune the front brakes. It goes in at the front brake line junction that is bolted to the chassis.

Are RED pads soft street pads? What manufacturer?

Dick Ruzzin

Hi Dick, as all the hard work was done well and the system works much better than on my other original setup Goose I am happy to leave it as is. The pads are from EBC and Redstuff type. They are a top quality street pad and not sure how soft they are, but have little brake dust with them. Mike

While I am at it,
does anyone have a source for motor mounts?
They are called, ANTI VIBRATION SANDWICH MOUNTS.

They are 75mm Diameter and 25mm high, M-12 bolts on each end.

I find them in catalogs of different companies but they do not make them duet the size, the taller 40mm ones are available, they size will not work.

I was wondering if Johnny Wood might know.
All the best, Dick Ruzzin.

Steve has some on eBay right now !

http://pages.ebay.com/link/?na...=web&id=321361096149

I understand that Ford powered Mangustas have motor mount problems with heat and oil.

If so you can get some adhesive aluminum tape, 2 inches wide, at Home Depot for a very reasonable price. The same tape is called "Racer Tape" in the performance catalogs.

Just take one turn around each one to protect it from oil and fumes and reflect 60% of the heat.

DICK RUZZIN

Hi Dick, there should be a protective aluminium shield that helps keep the heat off the engine mounts. They seem to work pretty well as 1302's are 70,000 miles old and still OK. Even so I have some of Steve's sets for the future. Mike

If you have that many miles on them I would change them.

Mine look fine, the first replacement set I have put in. But I started to get a vibration through the shift linkage and a lot of forward and backward motion to the shift lever when I accelerate in gear, or back off of the throttle. Also I started to get the "feeling" that the whole power train was loose, hard for me to explain. I suspected a bent rod or bent pushrod somewhere because of the vibration. Wires and plugs were good. As I said they look like new.
Last week I loosened both and rotated them 180 degrees and went for a ride, I could feel a real difference but the car is not back to where it was when they were installed.

Another thing that happens can be felt on high speed curves, 70-80 mph, you can feel a lightness coming and going in the rear as the car jounces over slight surface imperfections. The engine is jumping up and down back there. That is a lot of weight to have moving around and not being tied down solidly.

That is what I deduced after putting in the new ones. Your car will drive much better and feel much safer.

Put some new ones on and also some new poly bridge bushings in and your car will be transformed.

Dick Ruzzin

Dick, I am presently doing work on the cosmetics of the car and after completing a bare metal respray will change mounts etc. The car is driving quite nicely at present, but still as you say worth changing mounts. Steve's mounts are top quality. Mike

Steve is sending me two sets.
I neglected to mention when I suggested new poly bushings that the two at the end of the large bridge at the rear are the ones to replace.

They are the culprits when experiencing camber change in the rear.
DICK RUZZIN

Hi Dick, yes I will replace these as well. Another issue with rear suspension on Mangusta's is the change in toe when the suspension moves through its full travel. On compression, if the toe is correct, as the wheel moves up the toe goes to toe out. I feel a lot of the poor articles re handling were having this effect acting on the rear suspension. Johnny Woods has written about this issue previously. Changing the top rear link to a double ended Heim joint allows this effect to be cancelled. Thanks Mike

Mike,
I saw Johnys article but do not see how it changes toe in. It seemed to me that the double ended Heims just aided in setting camber, allowing adjustment without removing one of the bolts at either end of the upper control rod.
Please explain.

Dick Ruzzin


Dick Ruzzin

It was my understanding that the benefit of replacing those end bushings with heim joints was to remove the binding and subsequent snap-release under load. The GT40 suspension design is similar in many aspects to the Mangusta but is fully heim jointed and works rather well. My old GT40 replica had some heims and some bushings and I replaced all the bushings with heim-joints. The difference was astonishing. Completely predictable and no snap response under extreme conditions.

Mark

Dick,

I agree with your thoughts on the rear bridge. The stronger you can make this area better. This flexing in the rear fame is only effecting camber however. Camber change through chassis flex is not desirable of course but the real problem on the back of the Mangusta is toe change as the rear suspension goes into bump. I spent a long time making laser jigs specifically for the Mangusta.

I also spent time studying the GT40 rear suspension and found the Mangusta to be identical in design except for one very important part - the top link on the Goose only has a Rose joint on the inside. On the outside (upright end) it has a "T" bar with bushings. This T bar means the top arm cant move side to side thus making it impossible to incline the rear upright in order to adjust the rear toe change under bump. It's hard to get your head round this until you have the spring and shock off the car, mount the laser jigs on the rear wheel and then wind it through it's travel so that you can see the toe change.

All Mangusta's I have worked on with the standard rear set up go from 1.0 degree tow in to 0.0 degree toe at full bump. In other words it toes out by 1.0 degree from ride height to full bump, very dangerous! I believe this is the main reason the Goose got such bad press in it's day. All they had to do was look at a GT40 like I did. If you read any chassis engineering book they all say to avoid rear toe out like the plague.
Having rear toe out is dangerous enough, but the Mangusta is even worse - it can bump into tow out in the middle of a corner!

Fortunately, this is very easy to fix with one simple modification. I remove the top arm and cut the "T" bar off and replace it with another Rose joint. This then makes the rear suspension the same as a GT40 - infinitely adjustable.

Then you can lean the rear upright back (effectively increasing the castor) until it bumps neutral or slightly into tow-in (a totally safe condition). Make sure you have enough Rose joint left in the rod of the top trailing arm. The rule of the thumb here is if it's and 18mm Rose joint you need a minimum of 18mm thread in the rod.

I did all this on Jonathan Roots car and spend hours and hours. I think it's way beyond the scope of the average alignment shop even if they have got 30K worth of Hunter equipment. Any owner would be better off doing it themselves at home because the alignment shop will get pissed off with it and not get it right.
Warning, aligning the rear of a Mangusta or GT40 takes a very long time!

Here is the principal I used to set the bump steer front and rear on the Mangusta
https://www.youtube.com/watch?v=LO07qmJ9zkk

In the above video I dont think the measurement from the wheel to the mirror is relevant.

There is another way of reducing (not fixing) this rear bump steer problem, by using much stiffer rear springs. This method helps by simply reducing rear suspension travel but also rips the top shock mounts out of the chassis on the early cars that have a two bolt crossmember rather than the later 4 bolt crossmember.

Johnny

JOHNNY,
I am going to send your description to Werner Meier the GM chassis engineer who changed the mounting of both my rear bridges. He reversed the engine-ZF suspension by hard mounting the rear bridge to the sub-frame with shoulder bolts and welded in tubes then he soft mounted the ZF to the bridge with three Corvette steering bushings. This resulted in an amazing change to the cars ride and handling and it nearly eliminated the feeling of weight bias front to rear even with a full tank of gas.

I like your approach as it addresses a different part of the rear suspension and seems an easy thing to do.
Thank you very much, I understand the principal now.

DICK RUZZIN

Johnny,
My car now is very well aligned, it feels neutral under hard acceleration and braking with absolutely no rear wheel steer. If I modify the upper link with the Rose joint and keep it the same length it is now what adjustment is then required to the upper trailing link?

Should the rear alignment be changed? If so to what?

Thanks,
Dick Ruzzin

Johnny,
My car now is very well aligned, no rear wheel steer at all under hard acceleration or braking. This with the original T end on the upper link

If I replace the T ends of the upper links with Rose joints, keep the upper link the same length as before modified, what alignment changes am I expected to have to make to achieve the desired castor?

It seems to do this I have to find a race shop that understands and can adjust bump steer, that is, zero toe out.

DICK RUZZIN

Your statement below. Am I interpreting it in the right way?

Then you can lean the rear upright back (effectively increasing the castor) until it bumps neutral or slightly into tow-in (a totally safe condition). Make sure you have enough Rose joint left in the rod of the top trailing arm. The rule of the thumb here is if it's and 18mm Rose joint you need a minimum of 18mm thread in the rod.

Hi Dick, I have set up one of my Mangusta's this way. You can set it up yourself as most alignment shops will not wish to spend the time and effort to get it right. Set up a laser pointer off the hub to allow tracking of the wheel as it goes up and down. There are a number of setups to do this on various websites to setup alignment. The adjustments are done with rear shocks removed and upper limit and lower limit of wheel movement are used as total movement datum. Check this with the original top T link setup. You will find as the wheel moves up to full compression the toe out will be displayed. As the lower trailing arm is shortened and top trailing arm is lengthened this toe out will be reduced. Should be able to get zero toe change or some small toe in improvement. These changes cannot be done with the fixed top link as the hub cannot get any caster change. I think this Mangusta problem has mostly been seen as an issue when changing throttle position while cornering or a change in gear under constant cornering. Hope this makes sense, Mike

Johnny,
Thanks for doing this. I assume this is all done with the original trailing link Heims attachments and the offset links at the hub carrier end .
I also have looked at the Ford GT and deduced that the Mangusta and the Ford were the same basic architecture but that the Ford was a much more detailed execution especially in the area of the bridge which is much more sophisticated, trapped to eliminate side movement.

I made a drawing last night and I understand completely now what happens.

1.
Upper link has to get longer to get castor.
2.
Lower link gets shorter to pull the upright back into the proper toe in, in relation to the front wheels.

Why could I not just firmly set up a laser on my hub with a board in front of the hub to track it as the hub moves up and down, in and out? I could then adjust the upper rod with the new joint while tracking it. That would get me the desired rear wheel movement, eliminating the toe out.

Since my rear wheels are now well aligned with my fronts I can do the rear wheel adjustment on both sides to the same values and then test the car.

I know that normally the rear wheels are aligned first then the fronts to that set up.
I may need some fine adjustment to the front wheels.

How does that sound?

Dick Ruzzin

Johnny,
In relation to your comment about the Mangusta and Ford GT taking a long time to align.
My car has new large diameterrear trailing links with right and left hand thread Heims joints on the ends so that they can be made shorter or longer in place without removing the end attachment bolts.
This makes wheel alignment easier.

I would make the upper link that way also.

Dick Ruzzin

Hi Dick,

Sorry I am so long responding. I am working on my barn and a Mangusta and dont have much time for anything else!

If you have changed your trailing links to L/H thread on one end this will make it much quicker to adjust. The only down side to this is you cant stop the bar/link from turning while you are tightening up the nuts without gouging the paint as you try to hold it with Vise-grips or pipe wrench!

You do understand me correctly, the top trailing link will get shorter and the bottom longer. The bottom link is only just long enough so make sure you have enough rod end in the tube when you have finished.

Mounting a laser on the hub and pointing it forward onto a wall will not work because the ark you see on the wall will include the ark of your A arms. This is why you have to shine it into a mirror and then back onto a piece of board that is attached to the laser it's self. Then you only record toe change as the in and out movement of the A arm ark is not recorded because of the mirror.

Please send me an email Johnnyrwoods@aol.com and I can send you pics of the laser jig I made and how I did the top link Rose joint mod. Resizing and posting pics on this forum takes too long. If I could upload any size picture and the forum automatically resize it to 200KB it would be SO much better (like uploading pics to ebay).

Also call me anytime, it would be good to talk. +44 781 718 7333

Johnny

Johnny,
I will email you.
My new trailing links have a threaded bung welded in each end that is configured with a six sided nut on it so you can turn the rod with a wrench. Works very well.

I look forward to doing this. I will then have a very solid rear subframe with my modified rear bridges and a corrected rear wheel travel with no toe out with the modified upper link.

Can you give me some kind of description of the resultant improvement in handling? Does having
weak and soft rubber bushings in the bridge make the problem worse?

I hope that those reading all of this realize how profound your modifications to the Mangusta rear suspension is.

Johnny,
Have you read my account of the modifications I have made to my car regarding the two rear bridges? With soft old bridge bushings my bridge would move 1/2 inch from side to side when shifting from 1st to reverse.
I will email you.
Thanks, Dick Ruzzin

Johnny,
My hub carriers, with the trailing links adjusted for good alignment, are sitting horizontal at the bottom. In other words the big bolt running through the bottom of the upright is horizontal.

Is that attitude changed with the new upper link after adjustment?

Dick Ruzzin

Johnny,
Your quote below:

quote:

You do understand me correctly, the top trailing link will get shorter and the bottom longer.

My crude drawing shows the opposite. Please comment.

Dick Ruzzin

Dick, I had the trailing arms reversed re lengthen and shorten. I originally made my top link with one left and one right thread and yes made for quick and easy adjustment and had I built in a way to stop it turning while tightening I would have kept it, however with the possibility of these coming loose I opted for right hand joints on all ends. This way if the ends do come loose the geometry will not change. With your relationship (toe) between front wheels and rears OK, before you replace the rear top links take a laser and get a datum to set up the rears once the adjustments are made. All the attachment points are as original, you only need some spacers to centre the top heim in between the top "EARS" of the hub. Your bottom long bolt will be inclined when adjustments are finished. Sorry I have no photos to show as my car is getting some bodywork done at present... Mike

Thanks Mike for your input.

Johnny,
Since I have always worked with drawings and I enjoy doing it I might make a three view full size drawing of the rear suspension since the pick-up points are few and simply organized. I can then, as it is currently adjusted, run it through the motions with the shocks off on the drawing twice, with the original T bar and also with a double joint bar, I will record that motion on paper. I will measure both sides and compare them as they may be slightly different.

Then I can create the required change and adjust the trailing links on the drawing accordingly. I will measure the Heims threads so I can make the required movement of the trailing links on the drawing and then translate them on the car, preserving the alignment.

With a drawing I can also move the bridge and inboard pick-up point for the upper bar toward the center of the car to see how that effects the upper hub carrier and trailing links. Maybe about five millimeters. That will also show
what happens when cornering. My theory is that camber diminishes on the left wheel if the right wheel is loaded, causing camber to increase there.

That will be an interesting study, I might engage Werner Meier who is a GM chassis engineer to review my "papers", even help me define the study plan. He is the one who spotted my bridge moving when shifting from first to reverse and he made the new bridge for my car.

After that I would drive the car and then have the suspension alignment checked and adjusted if required.

The only fly in the ointment is the fact that the Mangusta, as other low volume cars of the era, is not dimensionally perfect. When my car was aligned on a computer driven machine the technician found it to be .04% off front to rear so he compensated for that. He said that was the best he could do because the chassis was not geometrically perfect. He did a great job.

Dick Ruzzin

Dick, Does your car have the gussets that tie the rear frame rails to the rear body structure? it was a late production addition.

DENIS,
No, my car does not have those. Can you send me a shot that shows the end that attaches to the wheelhouse?
Thanks.

Dick Ruzzin

Johnny,
You know more abut the rear suspension than any one.

Can you tell me what the offset clevices at the hub carrier end of the trailing links do?

Are they some kind of anti-dive mechanism? Or do they simply move the attachment point to the hub carrier outboard?

Do you recall what they did when you ran the suspension through its paces without the shocks attached?

DICK RUZZIN

Hi Dick,

I dont know why they have offset clevices. I know they have to point side ways because if you have them pointing up the Rose joint cant be attached because it exceeds it's misalignment. They do offer a little sideways adjustment to help the trailing arm clear the chassis and the exhaust. When I had my laser jigs set up I could not see any change to the bump steer by moving them within the limited travel available.

I will be interested to hear how you get on with your drawings. I too found the car to need more adjustment one side to the other. This is all part of the charm of a hand made car!

Johnny

Is the new format not working?
I have not seen a single post since it went into effect.

Dick Ruzzin