JEFFCO FNR discussion - preference

[yoshi]

Originally Posted by Chet

If I can't find a suitable diff here in the USA soon (still waiting for the Transworks) I now plan on importing the Elite Racing diff. It has a proven record in the UK and can be mounted in any position so it appears suitable for sports car and sand rail use.

Any interest or comments?

Thanks
Chet

Is there some reason you don't wanna buy the only unit that is holding up to decked out busa motors, instead of getting something that is un tested in our terrain that actually cost more than the Jeffco?........

[masterfabr]

Depending on usage the jeffco is NOT the only unit there is. There is very little info out there as to what makes a jeffco tick.Got any meat and potatoes info on the jeffco other than you like it?

[yoshi]

Originally Posted by masterfabr

Depending on usage the jeffco is NOT the only unit there is. There is very little info out there as to what makes a jeffco tick.Got any meat and potatoes info on the jeffco other than you like it?

I know it's not the only unit, but it's the only unit I know of that is holding up to a busa motor. I've talked to quite a few people that have trashed other FNRs, and i've talked to 6 people (some of whom built multiple rails with the Jeffco unit) with the Jeffco, 2 of which were high hp turbo applications, and it is the only one I know of that hasn't failed.

Can you name a single unit, besides the Jeffco, that has not blown up, and has held up to turob busa powerplants in the sand for years?

It's not the only option, but it is the only proven one in our application that i'm aware of....

[masterfabr]

I'm not going to get into that line of discussion since there have been reported failures of jeffcos also.ANY box can fail.Hell,I know there are people that will swear by a TW box. I just would like to know what makes a jeffco tick.We have all seen the inner workings of nearly every box out there.Why is it that there's no info on the jeffco inner workings? I haven't looked in a while but if there is any I haven't seen it. Yoshi,since you are a proponent of the jeffco why don't you provide a service to the members here and put up pics and info on the inner workings of the jeffco? Please do not try and turn this into a "fabr's bashing the jeffco" thing. I have not and will not bash it. But your statement that it's the only one that has held up is IMO a little biased. Also since you are a user of the jeffco it would be nice of you to invite him to participate in this site as Dan Roberto has been so generous to do.Dan has been very open and informative about his unit.

[Chet]

Originally Posted by yoshi

Is there some reason you don't wanna buy the only unit that is holding up to decked out busa motors, instead of getting something that is un tested in our terrain that actually cost more than the Jeffco?........

Yoshi - My reasons are as follows -
1. I strongly prefer NOT to use a chain drive setup.
2. The Elite has quick change gears.
3. Weight

Still looking for suitable USA alternatives but haven't found any yet.
Thanks
Chet

[yoshi]

Originally Posted by masterfabr

I'm not going to get into that line of discussion since there have been reported failures of jeffcos also.ANY box can fail.Hell,I know there are people that will swear by a TW box. I just would like to know what makes a jeffco tick.We have all seen the inner workings of nearly every box out there.Why is it that there's no info on the jeffco inner workings? I haven't looked in a while but if there is any I haven't seen it. Yoshi,since you are a proponent of the jeffco why don't you provide a service to the members here and put up pics and info on the inner workings of the jeffco? Please do not try and turn this into a "fabr's bashing the jeffco" thing. I have not and will not bash it. But your statement that it's the only one that has held up is IMO a little biased. Also since you are a user of the jeffco it would be nice of you to invite him to participate in this site as Dan Roberto has been so generous to do.Dan has been very open and informative about his unit.

Only failures reported were when he first started of a slight oil leak around the seal, the unit has not failed to my knowledge, as a leaky seal just means you need to add oil every now and again, and regardless, that was a problem with some of the first units built years ago. If you have talked to anyone that has blown up a Jeffco unit, I would love to hear about it, i've talked to 5 people that have blown up their TW unit, some withen 5 min. just like me.

What do you need to know about the internals? It's a planetary system, you know how they work, the planetary spins the diff below it, which is no different than a VW diff I believe. No trickery or top secret technology, just one hella stout planetary system which you prob. no more about than most.

And i'm not gonna pull one of my customers $3600 reverse units apart and take pictures [Off-topic text removed]

[Danno]

Hi Guys,

[Some text removed] And thanks to Mf for the mention. From what I know, the Jefcos are a planetary gearbox but I could be wrong. They make some really good stuff for the drag racing folks and most of that is planetary. This means that torque is distributed through several (planet)gears surrounding a "sun" gear and they are surrounded by a ring gear (teeth facing inward toward the sun). Not cheap to make but they have the advantage of many gear faces sharing the load instead of one gear to another one. I've had some ideas on how I'd like to use this type of arrangement in a new design but have opted to increase the pitch size of my gears and use higher capacity bearings as well. Yoshi, if you haven't taken a look lately, there are a couple of new pics on my site that give you what you had asked for as far as in input splined shaft with an input brake. I still have a case with your name on it to put together. A lot of the Rhino guys are making this switch (the Rhino caliper is pictured). BTW, there are guys who can break an anvil in a sandbox! Yoshi?

Danno (RPM) www.rpmgearboxes.com

[masterfabr]

Yoshi,must be something "secretive". Seems like no one has an idea of the actual internals.Like I said though you won't be dragging me into a poo fest against anyone in this thread.BTW no need to be getting defensive,yoshi.I did not ask YOU to disassemble a thing . I did ask you to ask jeffco to participate here and if you had info as to the internals to post the pics and info.WE all know there's a planetary in it.

[bajatex]

I would like to give some input here. This might sound like BS but as I was reading this post my phone rings and it's Jeff Boyd of Jeffco. I haven't talked to him in about a month but we stay in touch. I have seen the internals of his unit many times and have witnessed the evolution of his box.
Jeff has had his reverse diff broken by a turbo busa but that was a couple of years ago with the first generation box and when it happened he immediately went to work on a solution and in the process scrapping tons of hours and money on all the old inventory. He went to a much stronger gear set that connects the planetary to the diff. Jeff has the luxury of making all of his own gears so he's not dependent on some outside gear manufacturer. He makes everything in house. Jeff is old school, he does not have the internet and probably has never been on it. He is just a guy that takes pride in making something as good as it can be made period no short cuts. It saddens me to say that Jeff is not doing real good these days
he has a liver condition that is not getting any better. He has never been a drinker he just got dealt a shitty hand. He has been in the hospital 3 different times in the lkast couple of months for a total of about 30 days.
Jeff's company is in good hands and they are buisiness as usual as far as producing quality products.

bajatex

[Gene]

Sorry to hear about Jeff's health and I know we all wish him well.

This is a good thread and everyone is keeping it positive. Thanks for that.

My TW is going to the sand on week from today and I expect it to work for a full weekend and longer. Chains suck period and it gets proven again and again.

Testing diffs sucks too and is no better than buying a chain driven car from a guy who fails to have a good design, uses stupid tensioning ideas or has crappy fabrication and quality issues resulting in alignment or other problems.

In the end it's about customer support. Everyone here knows that Jeffco, RPM and TW have supported the product. All of these products get continuous improvement to make them better.

As always I will report back with results soon.