TCS Shift Linkage Center Bushing - Polyurethane

[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

[3929R]

I installed the bronze oilite bushings on the linkage at the shift lever and put the linkage back into the car.  With new bushings at the shift lever and center pivot I was able to determine that one of the roll pins at the center pivot was worn and allowing movement.  I put in a new roll pin and the whole linkage is as tight as it ever was and I can now find the gears!  (The linkage at the transmission is tight so I am saving any mods to that for another day.)  The car is much more enjoyable to drive.  I can shift through and know what is where.... except for 5th. 

I can not shift into 5th.  But it was there a month ago and though SLOPPY, I could pop it into 5th without too much agony or searching!  Now I can not find it at all.  I believe that on my TCS the reverse and 5th detent cam ramp profile has been modified such that it should be (and was?) easier to shift into 5th (see picture below).  I need to double check but I see no evidence that the detent mechanism has slipped or come out of adjustment.  Thus I am hesitant to mess with it.   

I am wondering if I changed the effective length of the shift linkage when I drilled a new hole and added a new split pin to the universal joint at the center pivot (part #FB9)?  It does feel as though I can push the shift lever too far left for 1st gear, though I'm not sure if this is too far left for reverse.  But how much could have turned the loose end?  Maybe 1/8 of a turn?  Is that enough to lose 5th? 

Any thoughts??  Is there something else I should be looking at?

[pboedker]

Hi Mark,

I've come into this discussion a little late due to summer vacation, but this all looks good. 

Your FB13 bushing, I believe, will work well and probably maintain its shape better and longer than the standard rubber bushing. Should be interesting if you will notice any vibrations from the stiffer material, probably not. On mine (rubber bushing) it had a tendency to slide through the pivot sleeve so that the pivot sleeve would grind on the bracket. I solved this by drilling for a set screw into the side of the pivot sleeve. So, just check if your new bushing stays put.

BTW (should I answer this post, the thread on our good old Europalist or both, sigh!) the alu block at your shift lever is precisely as mine. And it should be with only 25 between the VIN numbers. But I think they all are alike from TC (late S2?) and onwards, it's just the paperwork that needs some updating.

About your missing 5th gear...
Provided that you haven't touched the detent cam and ball, the problem must be in the middle joint. I don't think the length change will be very important, but maybe you've turned it a little bit so that the shift lever itself is not able to move far enough to the right. The lever goes through the ball joint and there's only so much movement possible left/right in the ball joint. Or the bottom of the lever could be restricted by something inside the tunnel.

The manual says to adjust a new linkage BOTH at the middle and then at the detent cam. Since the detent cam follows the internals of the gearbox, your's must still be good and it's just a matter of rotating the front part of the linkage sufficiently.

I had a similar problem because I broke the forward part of the middle universal joint on removal, so it had some threads left but not enough to put a pin through it.  But I made quick and dirty fix using a lock nut instead and it hasn't loosened in 9 years now. The nut had to be grinded flat so as not to interfere with the ball joint and the fore/aft motion, but it really gave an infinite possibility for the angle adjustment. I'm not saying it's good and stable solution, just that it was a desperate try that ultimately turned out to solve the problem OK.

[3929R]

Thanks for the reply Peter.  I really appreciate the insight.  I am happy enough to just have you reply here.  I also posted my question to the Europalist just to cast a wider net, and possibly get more feedback.  So far no replies on the Europalist. 

I've got some time today and I'm going to tinker with the middle joint.  What you said about the length not being very important but the rotational adjustment being off enough to not allow me to reach 5th makes sense.  I have to figure out how to adjust it back without drilling so many holes for pins as to trash it.  Currently it has 2.5 pins on the front threads and 1 on the back.  The .5 being some odd solid pin on the collar(further toward the front of car than the original pin) that does no extend all the way through.  Removing this may be difficult as its hole does not extend through.  I may convert to a lock nut, such as you and others have done. 

I did notice some minor vibration on the gear shift while driving but not enough to be any sort of annoyance.  I will keep an eye on the bushing in the pivot sleeve and if it slides, use your set screw idea.

[3929R]

1 step forward.  2 steps back.

Part of the reason that I couldn't find 5th is because one of the bolts that anchors the middle pivot to the bell housing was missing .  I didn't take it out but I should have noticed it was missing.  I replaced the bolt (it is the same diameter and pitch but longer than the bolt above it in the bell housing) and could shift into 5th in the garage.  Took the car out on the road and shifted 1 to 4th, then a grind and bam the shoulder bolt on the bottom of the shift lever sheared off causing the shift linkage to fall uselessly into the frame tunnel.  I pulled over, reached into the frame tunnel, and managed to get into 1st gear so I could crawl home. 

I don't see how the attempted shift into 5th could have sheared the bolt unless it was already damage and just waiting for an excuse to fail.  I think it must have been damaged due to over tightening when the bushing was missing.

Anyone have a spare shoulder bolt for the bottom of the shift lever on a TCS they are willing to part with?  RD sells them but I think they are not the same dimensions as stock. 

[3929R]

....using a lock nut instead and it hasn't loosened in 9 years now. The nut had to be grinded flat so as not to interfere with the ball joint and the fore/aft motion, but it really gave an infinite possibility for the angle adjustment. I'm not saying it's good and stable solution, just that it was a desperate try that ultimately turned out to solve the problem OK.

Any idea what size nut you used?

[pboedker]

Keine Ahnung 

I live in the metric part of the World, but just happened to have a spare nut in the rights size apart from the height that was adjusted with a file. Oh, and I should add that it wasn't a 'lock nut' as we know them with the little plastic insert, it was just an ordinary nut that now prevents the linkage tube from rotating on the threaded part of the linkage.

[EuropaTC]

Any idea what size nut you used?

Mark, just to make sure I've got the right joint, are you talking about the one in the middle, connecting the fore & aft linkage tubes ? 

If so, the manual infers that these are 1/2" UNF but the front one (the one with the engine support) has a RH thread, the rear one is LH threaded. You can buy thin lock nuts in both threads, I bought some in both RH & LH metric threads last year from Ebay. No doubt a bit of googling would get you a local supplier, although they sound odd it's not like some of the custom built Lotus bits where you just can't get them any more.

Brian

edit to add....    I don't know if this link will work, but in the UK places that sell motorsport kit tend to have them in stock because they use them with RH & LH threaded rose joints (heim joints over there )   I bought my metric ones from here but no doubt you will be able to find a local source.

http://stores.ebay.co.uk/McGill-Motorsports/UNF-Half-Nuts-/_i.html?_fsub=5570177&_sid=222097034&_trksid=p4634.c0.m322

[LotusJoe]

If you can spec out the bolt I'm pretty sure McMaster Carr will have it.
www.mcmaster.com/#shoulder-bolts/=itjiqr

[3929R]

Mark, just to make sure I've got the right joint, are you talking about the one in the middle, connecting the fore & aft linkage tubes ? 

 
Yes that is the one and this is the info I needed.  Thanks. 
(For Yanks these are called "1/2-20 jam nuts" with right hand or left hand threads)

If you can spec out the bolt I'm pretty sure McMaster Carr will have it.

They don't.  The shoulder length on the original is shorter than available through McMaster Carr and the shoulder diameter is an odd size.  According to dial calipers the diameter measures 8.64 mm, which is 0.34" or 11/32".  I am trying to find an original shoulder bolt  because I already have machined Oilite bushings to fit.  If I can't find one, I may drill out the holes in the linkage and shift lever to the next larger standard size.  This will make it much easier to find a bolt and bushings.  I think this what what is needed for the bolt and bushings that RD sells=>

[3929R]

Just to tie up this thread, I am now enjoying the full benefit of my 5 speed transmission. 

I removed the split pin in the aft tube at the center joint and instead installed a jam nut.  This allows easy rotational adjustment and I can now shift into reverse and 5th. 

As a temporary (or maybe long term) fix for my broken shoulder bolt at the bottom of the shift lever, I am using a generic 1/4" bolt (the type with no threads near the head) and 1/4"ID x 3/8"OD bronze flange bearings.  These parts were on the shelf at a local hardware store.  I used my Dremel and bench grinder to shorten the bronze bearings and slightly reduce the thickness of their flange.  The head on the 1/4" bolt was too small to engage the stop on the front tube, so I had a neighbor weld it to a washer which I trimmed to fit the stop. 

The 3/8"OD of the bronze bearings is slightly smaller than the hole they fit in on the bottom of the shift lever.  But the amount of play this causes is very slight (negligible?).  I have  driven no other Europas to compare it to, but I think my shifting is as good as it ever was and nearly as good as it can be without major redesign.