Tie bar bushes

[Declan_Burns]

I tried out a new polyurethane resin for the tie bar bushes yesterday. The result looks very promising. This resin has a range of 40 ... 70° shore depending on the percentage of hardener. The first samples are a tad on the soft side but I will measure the shore grade when fully cured. Next step is to add colouring pigment and up the percentage of hardener if required. This resin is very easy to cast at room temperatures and even without a vacuum pump produces very little air bubbles. It is a lot cheaper than the Weicon 60° shore urethane resin I used when I first made them back in 2011. They actually held up very well and still look perfect 7 years and a lot of miles on.
The MG TD shackle bush in the first photo also looks promising. These shackle bushes cost 11 pounds each to buy from the big guns. The TD has 8 such bushes so it is a worthwhile experiment.

Regards
Declan

[burnham28]

No Ginger ones then !!!

[Declan_Burns]

Here's the 3D image
Regards
Declan

[philthehill]

Declan
All looking good.
It is nice to see that you have included the protrusion that fits inside the hole of chassis tie bar bracket.
Most of the bushes supplied today seem to be without the protrusion. The protrusion was an original feature of the BMC tie bar bush and it is important that it is there as it helps stop the tie bar chattering against the tie bar bracket metal.
Phil

[les]

Yes I noticed that detail, spot on!

[philthehill]

Declan
Can I suggest that the bushes come in two shore compositions and two different colours - it is usual to fit a poly bush to the front of the chassis tie bracket and a softer rubber bush to the rear of the chassis tie bar bracket.
Having the two different shore compositions will give good resistance to braking forces if the harder bush is fitted in front of the chassis tie bar bracket and good articulation if the softer bush is fitted to the rear of the tie bar bracket and having the two different colours will differentiate which bush goes where.
Phil

[Declan_Burns]

Phil,
I am considering just making the 60° rear bushes and doing them in brown. Brown pigment is available for this resin or just leave them white. I could of course do both as a set.
Brown would probably be the best as it would be easily distinguishable from the standard (Blackpool rock) polybushes
available from the usual suppliers. They measure up at 87° shore.
Regards
Declan

[Declan_Burns]

I have just measured the white bushes and they cured at 65° shore-just nice!
Regards
Declan

[philthehill]

Declan
Many thanks for the detail above.
Your production of a 65 shore bush for the rear of the tie bar bracket falls into a similar consideration as my suggestion above - the 87 shore bush can be used in front of the tie bar bracket.
Regards
Phil

[Declan_Burns]

Phil,
Do you happen to have an original tie bar bush where you could measure the height and diameter of the protrusion? If yes could you also check the thickness and the OD. The measurement I used were from a repro.
Regards
Declan

[philthehill]

Declan
These are the measurements taken from an original tie bar bush Pt No: ACA5264 and also checked against a NOS BMC tie bar bracket Pt No: AAA 1531 and tie bar PT No: AAA1529.

The height of the protrusion.......................................3mm.
OD of the protrusion................................................16.5mm
OD of the bush .......................................................31mm
Height of the bush not including the protrusion.........16.2mm
ID of hole through bush............................................8.4mm
The OD of the front part of the tie bar on which the tie bar bush sits.......9mm.

I hope that the above is of help.
Regards
Phil

[Declan_Burns]

Thanks Phil,
I will have to increase the size of the protrusion which is not a major issue but other than that I am fairly well within spec. The repro bush I bought years ago had a hole size 9.3mm and that is what I used. It centres quite nicely once fitted but I will go back to the original dimension you have mentioned above.
Black and brown pigment scheduled for delivery in the next hour.

Regards
Declan

[philthehill]

Declan
A couple of additional dimensions which may be of use.
The total thickness (that is the bracket and the two welded on cup washers) of the tie bar bracket is 8mm.
The ID of the hole in which the tie bar bush sits is 18mm.
Phil

[Declan_Burns]

Thanks Phil,
Protrusion now corrected and test sample in the mould.
Regards
Declan

[Declan_Burns]

The 65° shore bush was not full cured. Yesterday it was 68°. I measured it this morning and it is 70° shore which feels spot on. It was the same with the first "Ginger" bushes I made. It took about 7 days to fully cure.
Regards
Declan

[Declan_Burns]

My first attempt with the pigment turned out to be a disaster. Too much pigment ruins the surface tension so I ended up with a horrible Indian red Swiss cheese bush. The consistency was however spot on. On the second attempt I only used a drop of black pigment and I am very pleased with the results. The red hue on the black bush is the release agent which washes off with water. Not quite industrial quality but should do the job properly.
Anybody willing to help road testing? I would send out a few samples.

Regards
Declan

[Sleeper]

I was wondering if you were going to produce for sale , as I 'd be in the queue but I've only done a few miles in my moggie before taking her down for the zetec conversion so I wouldn't be in a position to compare...

But let me know when they're on sale...

John

P.S I think they were only joking re. the " Ginger Bush "

[Declan_Burns]

John,
They weren't joking. I did make "ginger bushes" about two years ago-they were too soft. They probably didn't taste good either.
Regards
Declan

[philthehill]

Declan
All looking good & with the 3mm protrusion too !!
Phil

[RobThomas]

A bit late in the day, but...if one of the bushes had 'protrusions' that were much (10mm?) longer then there would be no way for the bush to migrate out of the chassis hole. You'd then need a female bush for the other side to accept the male protrusion. On one of our cars the tie rod rattled round in the chassis hole after the protrusions wore away. I guess the 3mm puts the break directly where the sharp edges of the hole are. Does this make sense?

Protrusions and Ginger Bushes. Starting to sound like a Benny Hill sketch.