Use of Marina front suspension arms and splined pin

Post by **philthehill** » Tue Jun 16, 2020 4:08 pm

Reference:- viewtopic.php?f=4&t=65731&start=20

In the light of the problems encountered in the thread (link above) I have been doing a little project over the last few days seeing if the Marina front suspension arms and eye bolt splined pin would be of any use as replacements for the Minor front suspension arms, eye bolt pin and location cup.
It has worked out quite well in that the Marina front suspension arms and splined eye bolt pin can be used as direct replacements for the Minor front suspension arms.
The Marina uses a Metalastic bush with spacer tube in the eye of the eye bolt. Unfortunately the shank of the Marina eye bolt is not long enough to pass right through the Minor chassis leg so has to be discarded.
A Metalastic bushs Pt Nos: FMK5137 & FMK5138 can be used in the Minor eye bolt but has to be shortened to 1 3/4" which is the same as the Marina Bush (note: when the bushes are used in the Minor eye bolt with Minor eyebolt pin and cup it is recommended that they should be shortened to 1 13/16" which is the same length as the eye bolt pin).
The Marina splined eye bolt pin does not have a shoulder so in practice the thin suspension arm can only butt up against the Metalastic central tube.
The Marina arms and splined pin could be used with top hat poly bushes but leaves open the chances of the thin suspension arm chattering on the threaded end of the splined pin. It is best if a Metalastic FMK5137/38 bush is used. Note: These bushes are out there but you may need to do a a bit of a searching.
The advantage of using the Marina splined eye bolt pin is that there is no possibility of the eye bolt pin and cup turning in the thick suspension arm. It also ensures that the thin suspension arm only moves with the splined suspension pin and the thick suspension pin.
The Marina tie bar bracket which fits into and holds the outer ends of both thick and thin arms together is a much beefier item and there is no need to use the spacer between the tie bar bracket and the thin arm as the bracket is deeper to compensate for the spacer removal.
Below are photos of the Marina thick / thin suspension arms attached to the Minor eye bolt fitted with a shortened FMK 5137/38 Metalastic bush.
In all probability these Marina arms and splined pins will be fitted to my Minor but with the Minor Mania negative camber Minor eye bolts fitted with Metalastic bushes.

: Marina eye bolt con 1.JPG (1.22 MiB) Viewed 693 times

: Marina eye bolt 5.JPG (1.37 MiB) Viewed 692 times

: Marina eye bolt 2.JPG (1.33 MiB) Viewed 690 times

Post by **RobThomas** » Wed Jun 17, 2020 8:23 am

I like the stuff you write, Phil. Always finding the definitive answer by 'doing it' first.

Thanks.

Post by **philthehill** » Wed Jun 17, 2020 9:40 am

Rob
Many thanks for the above comment.

Phil

Post by **ColinChandler** » Thu Jun 18, 2020 7:31 pm

yes. Thanks from me too. Always loads of great info in any post usually with photos too. Perfect.
Best wishes, Colin.

Post by **philthehill** » Wed Jul 01, 2020 2:36 pm

Many thanks for the above comments.

I have decided not to use the Metalastic bushes in my Minor Mania negative camber eye bolts. Currently they are fitted with the Minor Mania hard poly bushes.
What I have done is to machine the forward end of the splined Marina eyebolt pins down to 3/8" dia (same as the Minor) and with 3/8" UNF threads, the pin was originally 1/2" dia full length with 1/2" UNF threads.
I also had to face off the forward face of the splined boss to give a greater load bearing area, the pins ex factory had bevels on their outer edges so reducing the contact face. Normally only one Minor Mania bush is fitted per side but I have used two shortened bushes to give a thrust face at the front and rear of the eye bolt.
Now I will be using Minor thin pressed steel front suspension arms as they have a 3/8" hole for the eye bolt pin. The Minor and Marina thin pressed steel suspension arms are near identical with small variations in shape and size of hole at the inner end.
The Marina splined eye bolt pin was machined to give a nice fit to the eye bolt hard poly bushes when all clamped together.
Pictures to follow.

Post by **philthehill** » Fri Jul 03, 2020 11:05 am

The length of the Metalasatic bush quoted above was taken from the March/April 1992 Minor Matters.
The quoted required cut length of the Metalastic bush is 1 13/!6". I would disagree with this as the quoted length of the non threaded part of the eye bolt pin is 1 13/16". If both pin and bush are 1 13/16" there will be no gripping of the Metalastic bush center metal sleeve and the thick and thin arms plus the pin will rotate in and about the Metalastic bush. The bush needs to be at least 1 7/8" to enable the Metalastic bush metal sleeve to be positively gripped between the cup which fits into the thick arm and the thin arm. The preload on the sleeve of the Metalastic bush is required so it turns with the thick and thin arms. The Metalastic bush rubber should rotationally flex enough between the metal sleeve and the rim of the eye bolt. If the sleeve is not gripped sufficiently the Metalastic bush becomes ineffective.
The length of the eyebolt pin is not set at exactly 1 13/16". Having measure several there is a variance in length above and below 1 13/32". The variance is ok if you are fitting rubber or poly bushes to the eye/pin, but for the Metalastic bush to be sufficiently gripped the eye bolt pin end faces must be at least 1/32" less than the distance between the end faces of the Metalastic bush metal sleeve.

The above might seem irrelevant when people are fitting poly bushes to the eye bolt but the Metalastic bushes are available (but now hard to find - I have just acquired four NOS bushes). They were and still are an alternative to the rubber bushes and in some ways better than the poly bushes as in most cases it is a case of fit and forget.
As an aside I have just trimmed (at 1 3/4") two Metalastic bushes so as they can be fitted into the rear spring front eye. Again I have ensured that the spring eye pin is at least 1/32" less than the Metalastic bush between end faces.

Below are the photos of the Modified Marina eyebolt pin, Minor Mania negative camber eye bolt (fitted with the hard plastic bushes) and Minor thin suspension arm.