View Full Version : the gearbox convo from the retro thread.....
i thought id start a new thread to save cluttering up the other 1 even more. lol
so following on from the gearbox convo in the retro car show thread,
i found this that might interest people,
http://www.libertysgears.com/faceplate-proshift.htm
any1 know if theres any companies like this in the uk? ive spent some time on google but cant find anything.
it seems like what me and scoff are after, but not exactly local lol
they also do a honda fwd box, might interest the civic boys...
any1 found anything out that might help us?
i found a lotus forum where they use my gearbox in the esprit,
and stole this...
grinding synchro teeth.
Has anybody ever heard of doing this? my dad has been building transmissions for over 20 years he says he used to do that on his old cars. He said he didnt know how it would work on. his words exactly "its either gonna shift like the dickens or grind like a mother ####er"
so after contimplating wether i should risk it or not i decided heh, why the hell not if it doesnt work then i can change it out i have plenty here, so i went ahead and did it but instead of every other tooth he took off 2 teeth left 3 took of 2 then left 3 all the way around, now i was really starting to worry lol.so we put it in and it accually shifts fine, it shifts really good ecspecially at high rpms like 8200 it went in fine no grinding. so i dont know if anybody has ever heard/tried this before but it works great for me.http://www.dsmtuners.com/forums/images/smilies/thumbsup.gif
Robert Bowen discussed this practice briefly on page 163 in his book "How To Rebuild and Modify Your Manual Transmission" . It's a "low-budget way to get synchronizer-free shifting." According to Bowen, Chrysler used this practice in 60's in their drag racing cars due to rules prohibiting aftermarket parts at the time. He says that, to paraphrase, it's a poor man's dog box conversion, although not as sturdy as the real thing, but the gears can be shifted without having to wait for synchros to do their magic.
they are taken off the engagement dog
Interesting, I'll read a bit more in detail when I have a few minutes but what does he mean by "engagement dog" ?? The synchro, the dog teeth of the gear or both ? Or does it mean the splines on the inside of the collar, which I think would be more successfull since it would increase the chance of a mesh with syncrho mis aligned slightly.
Stu i spoke to scoff a bit about this via pm. spoke to pete doughty this week and he suggested converting your existing box to dog engagement my machining off the synchro ring and hazing a new ring welded on and machined up this is considerably cheaper than goin full straight cut gear set with dog engagement however if straight cut is what your after he can do this but generally he looks to do 3-5 sets at a time at around 3k. Pete has been doin cossie box's for years and he was the first person to do a 7 speed cossie box he knows what hes doin! hope that helps a little.
Ross, could you ask for a price to convert to dog engagement on 2nd, 3rd and 4th syncros?
That's basically what is done in the link above.
Not bothered about straight cut at the mo.
I will look into machining the STD syncros more for now and will let you know what I find out.
Straight cut is weaker than heli anyway.
Straight cut is weaker but sounds the bollox.
Some1 else I know has a straight cut box from pete in his 500bhp escos.
He's given me his number so I'll give him a bell see what we can do.
I will sort something. It's just when lol
I have no time or money lol, cars bleeding me dry.
stolen from the same thread,
I will attempt to explain although you may need to have the hub, slider, gear, synchro assembly in hand to fully understand.
The springs in the hub push the keys outward against the slider. The keys rest on the slider and move with the slider as you shift gears. When you shift gears the keys mate with the synchro ring and push the synchro ring onto the cone of the gear as you shift toward that gear, this is what matches the gear speed to the slider speed and prevents that gear grinding noise you may hwear with worn synchros. The keys are free to move up and down on the slider but the pressure exerted by the springs keeps the key movement some what in line with the slider movement. The stronger the force exerted on the keys outward toward the slider the more the keys will move with the slider and press against the synchro which mates with the cone on the gear.
also very interesting
If you run two springs on each side of the hub instead of one it can help high RPM shifting, the only downside is that shifting 1 and 2 may be a bit more notchy, but not much at all, it was hardly an issue for me.
I discovered this when a trans came to me with this mod already. I have run it on my car with the double synchro 2nd gear but i dont think it is really all that necessary with the double synchro 2nd gear.
im getting a spare box and will try these mods to it.
I used to drag race a 4 speed Monte Carlo with a built 355 years ago. All of the transmissions I built for that car, I took off every other tooth on the synchro. It absolutely made the transmission shift better at high rpm especially under a full power shift. However, I would NEVER do this to a street car transmission as it will cause accelerated wear under part throttle shifts as well as making it harder to shift under part throttle. This should be considered a strip only mod, where the transmission will be torn down on a regular basis.
They're taken off the engagement dog, not the gears
This is me this time lol
I spoke to pete this mornin, he told me to get every other tooth machined off the gear and selector ring not baulk ring.
I'm gunna get that done then rebuild my box with that and 2 springs per synchro to.
I'm going to send him a STD box to see what can be done.
Chris Hebden
18-06-2010, 10:22
I was thinking about this removal of one tooth every other and i got it to kind of makes sense in my head.............................. :crap:
Wouldnt this give the oil a smooth surface to release off due to centrifugal force? There is more of an area to allow more oil to be released and allow the gear to spin free and not 'hold' the gear due to friction between the two close teeth?
This is me this time lol
I spoke to pete this mornin, he told me to get every other tooth machined off the gear and selector ring not baulk ring.
I'm gunna get that done then rebuild my box with that and 2 springs per synchro to.
I'm going to send him a STD box to see what can be done.
good stuff stu! might i have some more gears to machine dog engagement onto soon then?
He's going to look at my box to see what improvements can be made.
Later in the year I'm gettin a new mainshaft and 1st n 2nd gears made.
I will get that converted to dog engagement, so won't be soon.
Do you fancy doin my std synchros for the STD box as a pj?
I'd be willing to get that done now, or I'm just gunna remove the teeth for now.
i dont actually really know much about gear boxs stu i just occasionally get bits from pete he tells me what he wants maching i do it and give it back or do the program for him. im sure he'd do your synchros for you if you asked.
Fair enough m8, pete will do it, I just thought u might have done it for beer money lol.
I will get my local machine shop to do the pikey version then speak to pete about the proper version later.
ok mate if you do that speak to pete first regarding machining evry other tooth off as if they havent done it before i think theres a certain way it needs doin i.e when the tooth is machined off you have to undercut slightly into into the spline for clearence issues i believe.
Will do, once it's apart and I've got the bits to take down I will call him again.
He didn't mention it this mornin, he just said get a machinist to take them off. But I will double check 1st.
interesting article about synchro/dog engagement
http://www.albinsgear.com.au/SyncroVsDog.php
Rob@Backyardracing
18-06-2010, 19:23
liberty are indeed well known in honda cirlces, and a lot of the big boys run there trannys/casings, there are a few others also though PPG being one. well catered for them lot. liberty do custom stuff also, not cheap though...
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