Bob_98SR5

well i spent the past 2 days searching clutch and synchro posts. ive seen quite a number of people wonder the same thing: is it my clutch going? or is it my synchros?

now i have about 125k miles on my 4runner. i know that the clutch can go farther, but i'm going to replace my clutch next week. that said, i have not seen a *single* how to, writeup, etc on how to replace the synchro ring. i have however, seen a lot of "its probaly the synchros"

so has anyone replaced the synchros in their manual tranny? if so, is it difficult? my guess is that the average shadetree mechanic will have a difficult time doing so and thats probably why no one has written anything about it.

feedback, advice, etc appreciated

bob

rimpainter.com

Yes, very difficult. You would be better off snagging a used tranny IMO. I fried a synchro in our 94 Accord and we were looking at $1000 for them to do it, or about $700 if I R&R'd the tranny and brought it in to the dealer, who happen to have one of the few specialists in the state that could actually work on those tranny's. Toyota may be the same.

Good luck Bob!

Bob_98SR5

christian,

yeah, i read about your accord in several threads actually, after reading the cost to fix, sorry for laughing

anyways, i had a feeling it would be big bucks to fix or replace. so what i've learned so far and checked:

1) check for loose/broken/cracked clutch pedal bracket - CHECKED; NO BENDING OR CRACKING

2) clutch freeplay - WITHIN SPECS

3) shift bushing - CRACKED; I'll replace this, but i dont think that this is it

4) tranny fluid - I'LL REPLACE WITH GM SYNCHROMESH based on threads; currently have Redline MT-90

I'm going to fix #3 and #4 this week and install my clutch kit this week. i am hoping that the clutch kit will do the trick. if its my tranny...wow, i can't afford this right now :cry:

bob

rimpainter.com

Bob -

That's ok, laugh all you want - I still haven't replaced the tranny (it's sitting in my garage on a shelf)

I have heard mixed reviews on that synchromesh stuff from GM. Be careful with it; as you know, it simply masks an underlying issue. Personally, I would replace the clutch and plastic shifter bushing first, then go the fluid route; but only to alleviate the problem if it still exists after doing those two things.

I have had vehicles grind into gear for both a worn out clutch or a busted plastic shift bushing. So, one of those could very well be your issue. This is a VERY durable 5-speed transmission. You would have to really flog it while putting down a lot of power to break it IMO.

Bob_98SR5

re synchromesh fluid: id say ive only read 1 or 2 things that were negative about synchromesh. apparently, the DSM and celica crowd love this stuff. anyways, good advice re clutch and shifter bushing first. ill do the shifter bushing and patiently wait for that clutch kit to come in. in the meantime, ill do a few more days homework on replacing the clutch.

thanks as always for your wisdom

bob

Finelygotone

Bob - Manual trannys might seem imposing if you have never been into one. They are, however, not that difficult to work on and repair. One thing that you need to have is a good local shop with a press and special snap ring pliers. (unless you have them) It is also nice to have a repair manual. I have always used opportunities like this to justify the purchase of somewhat expensive repair tools. Once you have diagnosed the problem, if it turns out to be a bad syncro - go buy some tools....

uberhahn

Bob,
i've used synchromesh on my talon with great success. However, as 96 mentioned, it simply masks the root cause, much like a steering dampener may mask vibrations.

I have taken apart my dsm transmission, and I am of average mechanical caliber. I did this out of necessity, as I could not afford a rebuild/replace. It was not fun. Depends on your risk tollerance I suppose. My 4R is a daily driver. If I was to do it, it would take the whole weekend. May require specialized tools.

Are you having issues shifting? For your syncrhos to be worn, something must have been applying pressure to them continuously.

uber

eric-the-red

Here's a write-up on overhauling the R151 tranny, if you want to tackle the job
http://www.4x4wire.com/toyota/tech/r151f/

Yoda

Hi Bo9b,
I've done synchros on other trans, and it wasn't terribly difficult (but I am a mechanic). It can get involved if you don't have special tools for some trans. That said, I have never been in a Toy trans, but do have one on the side of the house that needs work....maybe someday.

Check to make sure you don't have air in the clutch hydraulic system. It is difficult to get all air out. Best to pressure bleed it to get continuous flow of fluid to purge air (has high spot in tubing that seems to trap air)

Bob_98SR5

hey guys,

thanks for all the great advice. after looking at my fsm and the time i think it will take me, my limited amount of time, my new contract job that starts next week, etc., i am just going to take this to my mechanic and have him install my clutch kit. if its not too much more, ill have him look at the syncrhos.

hopefully the new clutch kit will solve the shifting problem. if not, ill have to have him tear into the tranny and fix that synchro.

bob

MTL_4runner

I have done quite a few manual tranny rebuilds on toyotas and they are not fun to say the least. Honestly, they are not as complicated as autos, but to me autos are alot easier to work on. You definately need to be skilled with a press to do a rebuild. If you had alot of time to learn then I'd say go for it but if you are doing this on a DD, then I'd take it to a pro to have them installed (that is one of the few jobs I would outsource on my vehicle).

Roadtripr

Keep us updated on whether changing the clutch cures the "synchro" issue. I have similar thoughts about my tranny.

Bob_98SR5

alright guys, one problem fixed, but another one created.

the clutch was replaced today by my mechanic, but there is this odd, harsh vibrating sound...though it could be (gasp!) that somethign is grinding against each other. i really dont know which one it sounds like. i will have to have someone drive it for me while i put my head down to listen.

first, what went right: the shifting is silky smooth. the clutch pedal action is sooo buttery smooth. ive been used to putting alot of effort to pressing that clutch pedal down. now i can gingerly press it down. i think i will enjoy driving in traffic now

what went wrong: in first gear, its fine. no harsh vibrating/griding sound. in second gear, no sound. in third gear, yes, there is that sound but only if i mash the pedal. in fourth gear, yes, i definitely hear it. if i put a small amount of throttle to it, i dont hear it. but when i put regular pressure on the gash or mash, boy, do i ever hear it.

i told my mechanic that i'd take it for the weekend and try to duplicate the conditions where i hear the noise, but i told him i wont drive it alot. i will take it back on monday and he will take it to his friend's tranny shop.

so has anyone experienced the same thing after a clutch install? if so, what was the problem and solution? Personally, i think it has to do with the clutch install b/c there was none of this noise before the swap---only the near impossible shifting into first and the stiff clutch pedal action.

oh, before i forget: there is a clutch pedal freeplay adjustment. after he put the clutch in, he said it was just as stiff before. he then read his manual and it said to adjust that and after that, the clutch pedal was smooth. so for those of you guys experiencing the same thing and aren't in the mileage period where you should cahnge it, you might want to check that out first before dropping the big dollars.

bob

rimpainter.com

It's possible this noise/vibration is a result of the driveline not being bolted back on correctly. When doing a clutch R&R, you are supposed to mark the driveshaft flange where it meets up with the diff(s). If not, you can get vibration. Look for a mark (that matches) on the (4) flanges. Other than that, I am really not sure how a clutch R&R could cause this noise. It's possible the flywheel bolts were not torqued down correctly or one is loose, but that wouldn't explain why this vibration is only rearing its head in certain gears.

Does it have transmission fluid in it? That would be an easy thing to check. It could be low or (gasp) non-existent. Or, it could be the wrong type.

Bob_98SR5

christian,

thanks for the troubleshooting tips. my guess was that something was not quite aligned correctly too. ill pass on these tips to my mechanic if he hand't thought of this already

bob

MTL_4runner

I have to agree with Christian because at first it sounded like maybe when he resurfaced the flywheel I thought maybe if it wasn't flat, you might have an issue (ie clutch chatter). I also though maybe if there was something wrong with the clutch disc springs you might get some vibration but again it should happen with engine RPM not only in higher gears. So to me it sounds more like something that happens as a result of speed......therefore when you do a clutch, nothing close to the engine will vary strictly in relation to vehicle speed. Therefore I think your answer lies after the output on the tranny (ie driveshaft, u-joints, etc) since those were also removed when he did the clutch. You should see some kind of markings on the driveshaft/u-joints if your mechanic did mark them for proper reassembly.

Bob_98SR5

Jamie,

Thanks for your analysis. i'm definitely going to have him look at that. ill take a look tomorrow too

bob

Bob_98SR5

PIIIISSSSED.

My mechanic said that they relooked everything over, including looking at the match marks, and taking it to a tranny shop. the tranny shop guy says he hears that noise in all the gears, so he *thinks* its a tranny issue

...how can a simple clutch job turn into a tranny issue

bob

uberhahn

hmmm...

you hear a metallic "grind" when you apply throttle in 3rd, 4th and 5th? Or when you "mash" the clutch?

i've never had anything similar, and I've had 6 manual transmission cars. only noise i've had has been clutch chatter. The fact that it is gear dependant makes me think that it's a transmission problem.

uberhahn

Bob_98SR5

well fellas, i am here writing you from the dealership. i took a test drive with the mechanic (nice japanese guy---like straight from japan) and he is going to take a look at the transmission.

what gets me is not that its a transmission issue...its that it was a direct result of the clutch being changed. that is, there was nothing like this sound prior and up to the time i dropped off my 4runner to my mechanic.

ill let you know what he finds out. i have a feeling that this will be a very expensive day for me or sometime in the near future

bob