DIY Polyurethane Bushes

[march]

Has anyone made their own poly bushes? I need to make some for a project (GRP4 TR7 V8 Rally car) as I cannot buy the size I need. The plan is to turn the bush on a lathe using 90A shore polyurethane purely because it is readily available, possibly freeze the material?

Any advice on this topic from someone who has done this before would be greatly appreciated.

[snowrx]

I'm guessing it would be cheaper to modify an existing oversize bushing, but you can cast your own. There's a Grassroots motorsports (or Classic Motorsports?) magazine article on casting your own bushings that I can't find, but heres some bushing fab discussion;

https://grassrootsmotorsports.com/forum/grm/how-to-make-your-own-delrin-an/140312/page1/

And of course YouTube;

 

[march]

Thanks for your response Thomas. I don't think that I will be going down the casting route but have bought a small length of polyurethane bar to try turning on the lathe. I have also found a possible solution with universal bushes from reputable suppliers (which will need modifying) so may go down that route.

[Bibs]

When talking to Brian Angus @brian_gt4 about the LOTAC bushes, a lot of research was done into the properties of the material for each bush to make sure it was suitable for the application. I'm no expert but from that I assume that not all polyurethane is made the same. 

[brian_gt4]

Lotus Engineering spent a year developing the Esprit polyurethane bushes with 'Polybush'. Several material specifications were tested to determine the correct material that produced the required Radial, Axial & Torsional stiffness that gave the required vehicle dynamics. Vehicle track & road testing was carried out as well as measuring the vehicle suspension movement on the vehicle test rig by the Lotus Chassis Engineers. Several other 'Off The Shelf' polyurethane bushes were evaluated but all failed as they did not produce the required characteristics or durability necessary for the Esprit. Brian Angus

[Bibs]

Thank you Brian, great to hear from you and all the best for 2022

 

[march]

On 31/12/2021 at 10:03, Bibs said:

I'm no expert but from that I assume that not all polyurethane is made the same. 

This is a concern I have, I will probably end up by buying a universal top hat bush from someone like Powerflex and modifying, unfortunately I need to make 4 sets of 2 which won't be cheap. As Brian's message also stated durability may be an issue but as this is for the track / Rally scene ultimately the bushes although working hard only have to last one event (although hopefully a lot more). If all goes well these will be tested later this year.

Thanks again for the comments - all useful stuff.

[eclat22]

Hi Marc, have you tried talking to Polybush, they were very helpful when I was getting bushes for my Eclat racecar

[march]

Hi, I have not contacted anyone, I will give them a call later this week. Thanks for the info.