Gear Linkage bushes / gear selector bushes

[JAMIE@JSP]

Hi buddy, im in no way saying fitting poly bushes will magically repair a gear box with failed synchros. in our gt4 we caught the issue as it began, i.e on the 1/4 mile unable to shift into 4th from high revs in 3rd allowing the gears time to slow down allowed us to change gear, so we called it quites as we had already reached our target for that day.
when we got back to the workshop we checked and the car would crunch into 4th but only at high revs under drag acceleration and abuse, we then fitted our poly bushes to the linkages and this gave us the ability to regain our 4th gear selection under the same conditions.

There is a reason these cars were designed with rubber and brass bushes as standard. the gt4 is a rally bred car and they still come with them, granted in some cars rubber bushes are used to make every day driving very smooth and boring for the enthusiast, but in some cases rubber bushes are required to insure correct tollerences are kept, and simply put, making these parts have no give means it has to give elsewhere instead.

when i say time i dont mean 5 min for it to change gear we are talking milliseconds as the gears align correctly with the syncho, we tested on both cars with short shifters and standard shifters but the results were similar for both, it all depends on the car, how it has been modified, if at all, and with what quality of parts.

 

[scot-ish]

Hi buddy, im in no way saying fitting poly bushes will magically repair a gear box with failed synchros. in our gt4 we caught the issue as it began, i.e on the 1/4 mile unable to shift into 4th from high revs in 3rd allowing the gears time to slow down allowed us to change gear, so we called it quites as we had already reached our target for that day.
when we got back to the workshop we checked and the car would crunch into 4th but only at high revs under drag acceleration and abuse, we then fitted our poly bushes to the linkages and this gave us the ability to regain our 4th gear selection under the same conditions.

There is a reason these cars were designed with rubber and brass bushes as standard. the gt4 is a rally bred car and they still come with them, granted in some cars rubber bushes are used to make every day driving very smooth and boring for the enthusiast, but in some cases rubber bushes are required to insure correct tollerences are kept, and simply put, making these parts have no give means it has to give elsewhere instead.

when i say time i dont mean 5 min for it to change gear we are talking milliseconds as the gears align correctly with the syncho, we tested on both cars with short shifters and standard shifters but the results were similar for both, it all depends on the car, how it has been modified, if at all, and with what quality of parts.

but ultimately, the sychro's in that car will shit themselfs again, whilst on rubber bushes, and when you change to jelly, they will only last a little bit longer again, haha, just messing.

but for a drag aplpication, surely that gear change time, albeit milliseconds, that little bit of times, reduces the boost drop off, and then reduces the lag time, and ultimately, will then give you a better time.

i offcourse, have rubber ones fitted, as my car is super fast road, and very little track/ drag strip, so i would like the synchro's to last that little bit longer. but if i wer building a car, solely for the 1/4 or track, i would use spherical. and when the time comes for a gearbox build, then so be it.

 

[JAMIE@JSP]

Jelly ones now there is an idea lol getting a mould would be the hard bit lol and what flavour to choose lol

drag application yes you want changes as sharp as you can, to be fair if you are noticing that much boost drop off at a millisecond, for one you can count very quick lol and secondly your turbo is waaaaaaay to big for your engine.

We use and recommend solid bushes for hard core draggers and trackers IF you have the budget to replace a box each season or sometimes twice a season.

each to their own, the information i have posted has been provided from much research product testing and development, and from some of the top track and drag racers in the class. all i am doing is simply relaying the facts in forum form.

 

[scot-ish]

aye, im not arguing, im just interested, and, sure i already know my turbo is way to big for my little 1.3 haha, but once i get to 5k it gets exciting haha. so its worth the little wiat, but with such a small engine like mine, those little milliseconds in the gear change would make a difference, but as i said, im not budgetting for gearbox builds all the time, so im quite happy with my rubber bushes.

its good when people come onto the forum like yourself who has tested things for themselves, as its nice to get other opinions in things, and ultimately, educates more people about there motors.

 

[Dave@TM-developments.com]

So what you are saying is that all linkages whether direct or cable should be rubber bushed to allow them time to mesh??? I cannot see this making any difference whatsoever to synchros. Smells of sales patter to me

 

[JAMIE@JSP]

no dave, what im saying is these are designed to have give, removing that give will cause it to go elsewhere. if something has a solid link it should stay a solid link if not then it shouldnt be changed to one. Keep using solid bushes in your cars and it wont be the smell of sales patter youll get lol

either way there are other choices out there for people who want something else. but do your own research if you wish or even have a 10 min read on imoc, mr2oc, gt4oc, celicaclub and youll see the same said time and time again by anyone who has an idea about these things.

Again only passing on my findings

 

[Dave@TM-developments.com]

I think you will find it has much nore to do with how people change gear then the type of bush used, by virtue of how a spherical bearing moves it has "give" as such, but only when needed. Cables stretching and fraying are just as much of a problem. Each to their own I suppose

 

[JAMIE@JSP]

im sorry where is the "give" you talk about in a spherical bearing?? the only movement it has is on an axes that the gear linkages dont use...

if they did then they would lock up when brass bushes were used..

The fact they can pivet in a direction the linkages dont move in does not give them "give".

The linkages only use push and pull along the length of the body, they do not twist they do not shimmy, and they do not do the shake and vac either.

i guess your information on these spherical bearings comes from the fact you had them fitted to your car with the zep cables etc?? (only from quickly scanning your posts) just because another company makes a part doesnt mean its a good design or works as they intended, infact id go as far to say that if it was the whole cables they make then they had to put a performance bush in there somehow and the usual roller skate bearing just didnt scream quality to their company directors so they made something look fancy but not perform and better or offer any other benifits over a solid bush.

unless im missing something with spherical bearings my usual understanding is they are used in rose joints etc and pillow ball top mounts as they need to rotate and also pivot, the linkages are not the same they only require to rotate and push and pull in one axes.

 

[Dave@TM-developments.com]

infact id go as far to say that if it was the whole cables they make then they had to put a performance bush in there somehow and the usual roller skate bearing just didnt scream quality to their company directors so they made something look fancy but not perform and better or offer any other benifits over a solid bush.

That would be the OE Toyota cables then as that is all is available.