Crunching into 5th

[W31SSN 83]

Anyone else had issues with 5th gear crunching when going in?Especially when on track?

Every other gear is smooth (thanks to Redline MT90).

[Arun_D 719]

A handful of times, yes. Very rarely though, I must say. Not crunched in any other gear.

 

I think I'm on the same fluid as yourself.

Edited October 11, 2019 by Arun_D

[Jack 499]

Trying adding some GM Synchromesh-friction modified to the MT90.....perhaps 1/2 to a full quart, with the balance being the Redline MT90

[vd9 149]

Same here, in 5th close to redline only with all the other gears being totally fine. Mine is on regularly changed Motul Gear300 75W90

[Maxi_z 106]

I am also using redline MT 90 and had some crunching of the 4th gear on track but just one or two times

Is syncromesh really different than the addittives that are already in the MT90? Would it not be the same then to switch to redline MTL?

BTW I Improved things by bleeding the clutch fluid (and brke fluid) to castrol srf

 

[Jack 499]

Maxi, the addition of a little, up to a quart, of  the synchromesh additive pictured above (there are 2 versions -- you want the one that says "Friction Modified") did make a difference on the Toyota C60x transmissions used in the S2 models when combined with MT90. MTL ( a 75W-80 grade) would not be the ticket.  The combo of fluids was a cure for a 2nd and 3rd  gear grinding/crunching many were experiencing  with those trannys (assuming the synchros were not already destroyed).   The additive increased the "bite" of the synchros to help them do their job.  Anecdotally,   we also found that changing the trans fluid often appeared to keep the trans happy.  By often, I mean with every oil change, change the trans fluid....cheap insurance.

We picked up on this "secret sauce" solution (combining MT90 with some AC Delco Synchromesh) from the Honda guys that were having problems with grinding, especially into 2nd gear, on the S2000 cars.

[Maxi_z 106]

Hi Jack

Thanks for the info

I read some of that about the Honda guys mixing synchromesh etc... But was thinking that the Redline was already using similar friction modifiers making the synchromesh mix not necessary.

With those manual gearboxes prone to crunching is not easy to find the best possible compromise if using them hard on track...

As of course you want the synchros to be not slippery but is MT 90 good enough for higher temperatures on track?

When I start to feel the gearbox less good on track I always wonder if it s because the synchros or if because too high temperatures for the oil that I use or both.

Will see If mixing synchromesh will make it better...

If you have other tips let me know...

Other than that stiffer engine and/or transmission mounts like innovative mounts improved the shifting too (especially on the old exige s2)

Don t know about SSC cables compared to the latest oem cables that look to be quite good

 

Edited October 14, 2019 by Maxi_z

[Jack 499]

Maxi, give it a try and do change the trans fluid often.   I've been using the combo on my 2-Eleven since new (2008) on a preventative basis and KNOCK-ON-WOOD, I've never had a synchro issue on my C60x trans.   Running stock synchros but with SSC stronger 3rd and 4th gears plus OS Giken LSD in the 2-Eleven.

[GFWilliams 1,895]

Are there any issues at all if you try and quickly put it into 5th when stationary?  It could be that the crosslink cable needs a tiny bit of adjustment.

[RedViper 83]

I sometimes get this problem into 4th. I also run MT90. Have done since car was new. Mine is more of a “struggles to go in (uuuhhh arr suit you sir)” rather than a crunch 
 

I was thinking that about the linkage adjustment but also thinking stiffer engine mounts could also cure but there is a distinct lack of options to upgrade  engines mounts and I’m reluctant to let anyone I don’t completely trust and who doesn’t deal with these cars regularly start messing with gear linkages

Edited October 14, 2019 by RedViper

[W31SSN 83]

I thought it might be gear linkage but I think 3rd and 5th are on the same link and 3rd is fine. With 5th it's as if I haven't depressed the clutch all the way. 

Do Back on Track have much experience with the gearboxes/gear linkage? They are not far from me in Guildford.

[Arun_D 719]

13 minutes ago, W31SSN said:

I thought it might be gear linkage but I think 3rd and 5th are on the same link and 3rd is fine. With 5th it's as if I haven't depressed the clutch all the way. 

Do Back on Track have much experience with the gearboxes/gear linkage? They are not far from me in Guildford.

I think @GFWilliams have provided them with ample opportunity in the past.

[GFWilliams 1,895]

Back on Track have done mine plenty of times, they’ll get it perfect for you