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TCS Shift Linkage Center Bushing - Polyurethane

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3929R:
WARNING- I am not a mechanic and don't know what the hell I'm doing!

I'm not sure where to post this.  It is not much of a technical article but just some pictures of what I used to replace the rubber bushing at the center link/middle pivot of the shift linkage on my TCS. 

In the parts manual for Type 352 and 365 transmissions this bushing is labeled part FB13- http://www.lotuseuropa.org/images/WorkshopManual/PartManual/tcf.pdf  (scroll down to find the correct drawing). 

My (stock?) rubber bushing was very worn, adding to my sloppy shifting woes.  The bushing is very close to the exhaust manifold and I think the heat may have hastened its demise. 

One fix is to replace the pivot with brackets and heim joints - http://www.lotus-europa.com/manuals/files/shift_linkage_mods/Europa%20TC%20Gear%20Shift%20Middle%20Pivot%20Assembly-1.pdf  This set up does not seem to provide any vibration dampening, which I think is why Lotus used a rubber bushing here. 

As rubber suspension bushings are commonly replaced with polyurethane, I thought poly might work here.  Polyurethane should provide some vibration dampening (dependent upon how hard it is) but be more resistant to high heat and hopefully last longer then the rubber.  I found small bits of polyurethane "tube" is sold on eBay.  I found one such piece with nearly correct dimensions, 1/2" ID x 1" OD X 1-1/2" Length, for $6.50 including S&H.  http://www.ebay.com/itm/370460163152?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649#ht_2072wt_780 

The poly "bushing's" OD was just a bit too large so I used my bench grinder as a makeshift lathe and turned it down a millimeter or so.  Then I greased it up, slid it into the pivot sleeve(FB12), and inserted the two steel pivot bushings(FB14).  I think/hope it will work.

The polyurethane I used has a Shore A hardness of 95, way harder than the stock rubber (~ 60?).  This may create less slop or it may mean it does a poor job at dampening vibration, but for the price I can always replace it with something softer.

I am now waiting for bronze oilite bushing for the linkage at the shift lever (bought from someone on the Yahoo group) before reassembling and testing. 

As I warned, I don't know what I'm doing.  I would greatly appreciate any comments, questions, or derogatory remarks.

Mark

LotusJoe:
Excellent modification. It should work much better than stock. I was thinking about doing the same thing except I was going to use Delrin instead of the polyurethane, but your solution should work great.

EuropaTC:
I like it Mark, mechanic or not, that's a very neat job. I replaced mine a while ago with rubber and never thought to use nylon but now you mention it, it does sound a much better solution.

Just the sort of thing to put on the "Winter Job List" !

Brian

Bainford:
Looks good, Mark. I will eventually turn my attention to improving the shift feel on my car and will keep this mod in mind. Thanks for posting.

cal44:
Thanks Mark.  Can't wait to hear how it works. 

I have the same issues and neither major supplier has these shock absorber bushings the alternate is to make something.   So here we go. 


http://lotus-europa.com/manuals/misc/transmission/tc_shifter.html

Mike

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