Diff and Chain Adjustment

[Mike Devins]

Just shipped this unit to Russ for his conversion It uses a Honda B16 open diff availale from the dealer (or a used one if you can find it), Taylor stub axles, and bearing carriers that I machine in house. This one was shipped with an open diff but can be changed to a Quaiffe and it is a direct fit. Chain adjustment is done using shims. This is the same unit that I used on Mike Siriann's DSR.

[RussMcB]

Oh, yeah. It's Christmas all over again. I can't wait to get it in my hands.

I want to take this opportunity to tell everyone that Mike has been FANTASTIC to work with. He has done a lot of extras for me, such as ordering parts, driving to the Honda dealership, not to mention answering a hundred questions about car building, materials, "How did you do this?", and "How can I do that?"

Mike has shared a lot from his experience from building the VD DSR (and other cars). For instance, he determined that mounting the diff bearing pillow blocks to the rear vertical tubes rather than front will make chain adjustments much easier.

I don't know if Mike wants me to share actual costs, but working with him has saved me $1,000+. I didn't go with a Quaife or LSD for a few reasons. Even if I had, working with Mike would have been less expensive than every other option I found. I could have saved another $250 if I had found a used diff. I just didn't have the patience to keep looking, even though there are probably plenty out there somewhere.

Mike, I stopped at Home Depot tonight and bought some 1" wood (meant for stair bannisters?). I plan to use your suggestion of building a practice subframe with wood before metal.

Thanks, man!

[sidney]

Mike, this looks a lot like what we are doing with a VW diff. I have plagiarized your mounting design, but you seem to have a different method of retaining the bearings in the carriers (snap ring, washer???). Would you mind sharing? Thanks!

[carnut169]

Remember that you need about 1.5" (min) of adjustment or a full chain link to properly adjust the chain when the space you need falls between two links. Make sense?

That diff looks great and I definately would have considered it had I known about it when building my car. What is the weight of this unit? I wonder what advantages a limited slip will give over an open diff...?

[RussMcB]

I wonder what advantages a limited slip will give over an open diff...?

Well, I was on the fence for quite a while as I talked to a bunch of people. It was interesting that some people thought LSD was the way to go while others thought open. I was really surprised when a few people thought a spool would be ok, too.

Here's what tipped the scales for me to go to an open diff: Cheaper, simpler, lighter and people like Craig Taylor, Richard Pare, Mike Devins and others thought open was the best choice for the F1000 power level. One or two people said lifting an inside tire isn't common in our low, wide cars. It would be even less of a problem with the wider F1000 rear wheels and tires.

I ran 8" wheels & FC-size tires on my Ralt RT-5 FSV (180 HP) with open diff for several years and never felt it hurt performance noticeably. That could be attributed to my skill level, though.

[sidney]

[quote=carnut169;126834]Remember that you need about 1.5" (min) of adjustment or a full chain link to properly adjust the chain when the space you need falls between two links. Make sense? quote]

Sean, based on the calculator I found below. I can only come up with a maximum of about 0.5" needed to go from 48T to 45T. You have to remove or add links, but the distance change is negligible. Maybe I'm using the tool incorrectly.

http://www.tsubaki.com.au/tsscs/chain_length.htm

[carnut169]

True but if that change falls between 2 chain links you have to go shorter and adjust... you have to be able to adjust the rear sprocket at least a link because it might end up that way unless you run a tensioner. Make sense? Its not a sprocket size issue rather a chain link length issue.

[RussMcB]

I think if you add or remove one chain link, the distance between the sprockets only needs to change by half of a chain link, right?

New question (still on topic, I think): I've never done anything with chains before. I understand there are two (or more?) kinds, and I may need to "break" and rivet links? What's involved? Special tools? Big deal or no big deal?

[formulasuper]

[quote=sidney;126876]

Remember that you need about 1.5" (min) of adjustment or a full chain link to properly adjust the chain when the space you need falls between two links. Make sense? quote]

Sean, based on the calculator I found below. I can only come up with a maximum of about 0.5" needed to go from 48T to 45T. You have to remove or add links, but the distance change is negligible. Maybe I'm using the tool incorrectly.

http://www.tsubaki.com.au/tsscs/chain_length.htm

Removing or adding links is not something you want to plan on doing unless you're using the clip style masterlinks. (not recommended since a departing chain can destroy an engine/tranny case). Most racers go with the rivet style permanent masterlinks. Therefore having as much adjustment as possible is best, IMHO. I have two permanent chains made up with one being one link longer, therefore I can fit any possible ratio combination. Once you have raced all your favorite tracks you will know what ratio to set up before arriving at the track.

[formulasuper]

I think if you add or remove one chain link, the distance between the sprockets only needs to change by half of a chain link, right?

New question (still on topic, I think): I've never done anything with chains before. I understand there are two (or more?) kinds, and I may need to "break" and rivet links? What's involved? Special tools? Big deal or no big deal?

Actually you must change two links at a time, since every other link is a narrow link.

[sidney]

It's a 530 chain with o-rings, but who makes the best?

As for breaking the chain, if you settle on a range of sizes of rear sprocket 45-47 then you shouldn't have to break it very often.

[carnut169]

RK makes the best chains and yes, absolutely get the rivet type master. I use the most expensive RK as I don't want a snapped chain tearing up the car (GB530GXW)- also plan on replacing it. DSR guys replace a chain after 2 weekends but they are heavier and more hp. I'll replace mine each season.
Scott is correct, you cannot just replace 1/2 a link.

Oh, lastly, get the RK chain breaker tool like this one:
http://www.sprocketcenter.com/p/1023...-tool-kit.html


I went through several less expensive tools before buying the RK kit.

[Mike Devins]

sidney the bearing blocks are simply bored to a set depth.

Sean, I did not weigh the unit as pictured, maybe Russ can post the weight when he gets the diff tomorrow.

[Matt Conrad]

Somebody mentioned using clip style links....absolutely NO....you might get out of the paddock...might. Our application requires riveted chains....Period. Most of the good chains have a specific rivet link for them too. The key is to use an O-Ring chain that provides around 10,000 PSI of strength. The RK unit Sean mentions is good and DID makes one as well....I believe it's a 530 ZVM. If it only comes in Gold....get gold....it's really just for looks for the two-wheeled guys. These chains are expensive, but a necessary item.

Sean,

OOPS...I thought I read session....Ommitted my comment here. As has been discussed before, here's some other things that can shorten a chain's life:

1. Lack of lubrication. Lubricate after each session when the chain is warm and use only lube specifically for o-ring chains as other stuff can damage the o-ring and ruin the chain quickly.
2. Too short of chain. Short chains tend to not cool well as they don't have enough of a "break" between going around the sprockets (which adds heat).
3. Too small of a front sprocket. We recommend a 15-tooth front as a minimum. Too small a sprocket puts added stresses on the chain.
4. Misalignment. The front and rear sprockets need to be perfectly aligned (particularly on shorter chains).

As far as chain tools....we've broken them all. Truthfully, I can't recommend one at this point. Sean's idea is the best. Have different sized chains pre-built and at the ready...and a spare of each size too. Building chains at the shop is much easier than at the track.

Mike,

I like the diff unit. We will be testing about three different units on our car (that use the Taylor/Quaife bearing carrier setup) but would be interested in alternate designs as well.

Matt Conrad
Phoenix Race Works, LLC

[John]

Cool,

Something I can help with.

I run a DSR, one of the very first Maloys that had wood floors, so it was really a bit heavy. Lets just say more than a Stohr. I also had one of George Deans best engines, so I am as hard as you can get on a chain.

To make a chain last, it must be adjusted correctly. Too loose and it will thrash around under gear changes and get streched, too tight and it will get hot. Bob Fox our resident "DSR Master" recommends about 1/2 to 3/4 play in the chain. I was suprised that it should be that tight, but he was correct.

Use a riveted chain if you can, but the links work ok as long as they are made for the chain. Bob Fox and Dave Arken both use a riveted chain on their cars, and I had one on for the last 2 weekends last year. If you use a clip, saftey wire the link on and put RTV on it, and face it out so you can inspect it after every session, also make sure the clip openinf faces back in the direction of motion of the chain. The ZVM Chain is the best but Tsubaki Sigma is also good enough.

I only need one chain length and we work the gear ratios accordingly we have 15-17 tooth fronts and 43-47 rears that gives us enough ratios to be at max RPM at the fastest point on any track we go to, from Fontana a 17-43 to Laguna with a 15-45. 1 tooth on the front is roughly 3 on the rear, and the front gears are cheap, so we can work to where we need.

ALWAYS, have a cut and assembled chain ready in your box of spares. I didn't at one race and that is why I have link chain on now. The chain failed for other reasons that normal.. The carrier got sideways in the holder and ruined the chain. Bob and Dave gave me one a clip chain, and to my surprise it works fine.

Be careful with the links, if you over tighten it throw the master away and do it again if you don't the master link just right chain will just fail.

If you get the chain right it should last most of a season. I got 7 weekends out of the first one last year. You should inspect the chain after every session, look carefully at it while you lube it to make sure that there are no missing O-Rings. Once the O-Rings are gone you have about one session to change the chain. So if you see a missing Oring throw the chain away and put in a new one. if you see any Blueing on the chain it is done.

Also watch the sprokets they will wear and need to be replaceed, if you are running at the same track all the time they will last about the amout of time as a well maintained chain.

What kills the chain is rough up shifting and downshifting, when you start you will not be smooth in your shifting and you will chew up chains, I use the clutch on every downshift so as to preserve the chain, gears, and especially clutch basket ( if you ever break a basket you will know why you never ever want to do that again) Once you are good at assembling chains, adjusting them, and are smooth in your shifting, You will change the chain 1/2 way through the season because it is time not because it needs it.

Hope that helps,

John

[carnut169]

Matt-

I said season, not secession.

[John]

Never ever change chain lenghts

If you need more than one chain length, make 2 different chains.

[teamfour]

I know I am resurrecting an old thread, but...

How does one get a diff assy like that?

[RussMcB]

If you mean that particular whole assembly, contact Mike Devins @ HRP. If you mean just the Honda diff, the Honda dealership or junk yard.

Other manufacturers offer different types of chain drive differentials. Taylor & Williams are probably the better known, but there are others.

[teamfour]

Thanks Russ. I am looking for the complete setup like you have. I have read your build writeup about 100 times. Thanks for sharing.

FWIW, I am converting an F500 to 600cc power for autox, and want to mimic the rear end setup found in FB.

[carnut169]

I would recommend the quaiffe TRE unit Taylor sells- pretty bulletproof.

[SCOTTY81]

Thanks Sean,

We have the new aluminum splined end bell and sprocket flange now.
If I can figure out how to post pictures....I will put it up.

scotty
Taylor Race Engineering
scotty@taylor-race.com

[teamfour]

I like the Taylor units. What appeals to me though about the Devins unit is the simple carrier setup. This would go into my setup very easy.

[Mike Devins]

I BELIEVE THAT YOU WILL FIND THAT THE UNIT THAT RUSS IS USING IS PRETTY BULLET PROOF AS WELL AND WILL ACT LIKE THE QUAIFFE UNTIL YOU GET WHEEL SPIN. WITH A 600 THAT MAY NEVER BE AN ISSUE.

THE OPEN DIF THAT IS USED IN THE ASSEMBLY THAT I MADE FOR RUSS IS GOOD FOR A 2800 LB CAR WITH 120 TO 180 HP. SHOULD BE NO ISSUE WITH YOUR 600 OR EVEN OUR 1K.

MIKE ,

LEE - YOU HAVE MAIL

[Billy Wight]

AND WILL ACT LIKE THE QUAIFFE UNTIL YOU GET WHEEL SPIN.

It will actually act beter than the Quaife until you get wheelspin (no preload), but then again, wheelspin is the problem! Hence a limited slip diff...

[Mike Devins]

BILLY,

THE SETUP THAT RUSS HAS IN HIS CAR USES A HONDA B16 OEM DIF. QUAIFFE MAKES A DIF THAT THE FSAE TEAMS USE THAT FITS IN THE SAME CARRIER AND ALSO HAS THE SAME RING GEAR PATTERN iF THE OPEN DIF BECOMES AN ISSUE YOU CAN ALWAYS UPGRADE (AVAILABLE FROM TAYLOR).

JON STAUDACHER WHO RUNS DSR WHERE THE POWER REQUIRMENTS WOULD INDICATE THE USE OF A LSD HAS BEEN USING AN OPEN DIF FOR YEARS AND HAS TESTED A QUAIFE. HE OPTED FOR THE 6# SAVINGS AND HAS GONE BACK TO THE OPEN DIF.

[SCOTTY81]

Here is our Aluminum spline diff.
This is the same diff but now in an aluminum version that Justin Pritchard ran in his Piper when he won the ARRC.

Scotty
Taylor Race Engineering