Crunching into 5th

[W31SSN]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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

[Toqcars]

Let me awaken this old topic instead of opening a new one...

I have quite new Exige (4 months). Was driving in on the track for the third time until I got it and noticed crunching when shifting from 4th to 5th gear under heavy load. Even if I press the clutch 1 second before I should, there is still short crunch. If car is not driven at full load, there is no crunching. Based on that I would say that linkage should be fine. 

Plan is to change the transmission fluid. Got recommendation from a very reputable team/tuner to use Gearbox oil Motul Gear 300LS M75W/90-LS. Not exactly sure why LS, since Exige Cup 430 lacks LSD. Is it possible that the LSD fluid makes Synchro Rings happier, just like the GM Synchromesh liquid you are using? Any experiences with it, or do you all use MT90 with the AC Delco Synchromesh or  Motul Gear 300?

[theplanner]

My crunch every time whether under load or not if I shift quickly 4th to 5th. Every other gear is fine.  I can prevent the crunch only by shifting a touch slower and be more deliberate with pulling the shifter to the right before slotting it up into 5th as opposed to a quick right and up motion. 

[Toqcars]

Well in that case I would suspect cable setting as well. Have you done anything to fix it besides changing your shifting behaviour?

[theplanner]

No I hvnt, I figured I can train myself to slow the shifts down…lol….kinda used to it cos I hv classic cars too..but pls do share if u found a fix for it.

[Toqcars]

That is totally fine solution for the road driving, not so for the track 🙂 Yeah my first attempt for it is changing the transmission fluid next week. Will update whether its better or not.

[SZ]

I assume you have same trans as Evora.  Same issue for 5th as you are having.  From what I have researched the trans just does not want to be rushed.  You can feel when it meshes if you gently lean into 5th and wait.  Only when quickly and high revving above 4k.  I used Motorcraft XT-M5-QS Full Synthetic and then moved on to 

BG Syncro Shift® II which is the best I have found.  Unfortunately a fluid change did not fix the issue.

[theplanner]

8 hours ago, Toqcars said:

That is totally fine solution for the road driving, not so for the track 🙂 Yeah my first attempt for it is changing the transmission fluid next week. Will update whether its better or not.

Ideally on track you want to shift as quickly as possible without reminding yourself to slow it down.  Nonetheless the difference is micro seconds so unless you are racing, dun think you will really be too disappointed with your track times as there are other areas where you can improve to make up the difference imho.

Watch this vid, and you see they experienced the same crunch going into 5th.  They were able to minimize/ prevent it by showing some mechanical sympathy.

I have to admit I have yet to take my car on track, so it will be interesting once I do if I still feel the same way about slowing down the shift…LOL.  My gearbox is out atm pending LSD install.  

[Toqcars]

I was always thinking what is the time difference between the fast and slow shift or the one with the mechanical sympathy, as you nicely called this phenomenon 😀 Not sure whether those would be microseconds, I guess it half a second. Please note that engine revs falls a lot during the slow shift 🤓

But I fully agree that it’s nonsense for the road and not important for the trackday… until you meet some friend on a track with a Porsche, thinking P is the only vehicle for the track 😂 Than you lose a lot when shifting in parallel with the PDK (personal experiences here) 😂

 

But by the end of the day… Lotus is a track focused manufacturer. Not all of us buy Lotus because of the track. But when I picked Cup430 instead of Elise (which is a great car) or instead of Sport 390 (which has far the best price performance ratio), I paid the premium just because of the track, miliseconds or microseconds. Just want the car to shift as fast as possible. But yeah, some people buy it to be a garage statue… which I also understand and support. Better Lotus in a garage than no Lotus 😀

Hey, I was also educated that the synchromesh is not ideal for track use 🤷‍♂️
 

Great for the LSD, really want to hear your opinion about it. I am hesitating because Lotus engineers said that the TC wouldn’t like the LSD. So really wonder whether would you drive with TC disabled or in race mode. And how would it be in RACE TC 👍

[theplanner]

On the 5th gear issue the synchro makes sense becos it felt like something not keeping up with the pace of shift.  Except its strange all other gears are fine.

On P cars let face it they’re a better all rounder, PDK or manual.  They r also far easier to drive quick plus the tc really flatters the driver.  I once took my gt3 on the skidpan and forgot to turn off tc, and i thought i was a drift god, till i noticed the tc light flickering away….lolol.  I didnt even feel a hint of intervention, except for how easy it was to carry the slides and transition. So I think you if bought the 430 to try to be faster than a GTS/ GT3, you really only have tyres, geo and great driving skills to help you in absence of other mods.  I don’t believe the Lotus TC is as well programmed as the P car’s.  But what the Porsche owner dun get is much more involvement, so even if you were slower you are having much more fun and require much more skill to complete the lap in the same time.

The reason I’m installing the LSD is I wanted predictability in how the car behaves when I am at or near the limits (my or the car’s) as I prefer to drive with TC off on track. Just have to slow down a little until you learn the car, then gradually pick up pace and consistently be mindful of the tyres limits and weight transfer.  This will make you a better driver over time even if your track times may be slower in the beginning.  The BS many go on about LSD causing understeer is simply not true as understeer is really down to alignment/ geo setup, tyres and drivers inputs (assuming full traction off).  Anyway, I will let you know how it drives once I get it on track hopefully in 3 weeks.     

 

 

 

[Toqcars]

On 08/04/2022 at 00:12, theplanner said:

But what the Porsche owner don't get is much more involvement, so even if you were slower you are having much more fun and require much more skill to complete the lap in the same time.

The reason I’m installing the LSD is I wanted predictability in how the car behaves when I am at or near the limits (my or the car’s) as I prefer to drive with TC off on track. Just have to slow down a little until you learn the car, then gradually pick up pace and consistently be mindful of the tyres limits and weight transfer.  This will make you a better driver over time even if your track times may be slower in the beginning.  The BS many go on about LSD causing understeer is simply not true as understeer is really down to alignment/ geo setup, tyres and drivers inputs (assuming full traction off).  Anyway, I will let you know how it drives once I get it on track hopefully in 3 weeks.

Heavily agree on this one. P cars are way easier to drive fast, but boring compared to the L cars. Especially if you track the PDK version.

 

LSD must be useful. I noticed lack of it first time on a track with A Lotus. Eventhough Lotus is claiming that LSD is not needed because of the lightness and aero and TC compensation... it's needed. But I am just pretty sure it will not work nice in the RACE TC. But since you are tracking it without the TC... no issues here. So yes please... we want one big long report of your LSD experiences 😀

 

Not to be totally off the topic... haven't changed my transmission fluid yet. But found out that many Exige owners experience crunching when shifting into the 5th gear and do nothing regarding it.

[Martrack]

Topic to report LSD experience (still interesting !) :
https://www.thelotusforums.com/forums/topic/86251-exige-the-diff-debate

Edited April 9 by Martrack

[Toqcars]

Changed the gearbox fluid. Fluid was more or less fine. No metals detected on the magnet inside. No irregularities detected.

However, gearbox is still crunching when shifting into the 5th gear. So I am suspecting the synchro on 5th gear. Not sure whether it would be possible to inspect it with a camera. Anyone tried?