Firman Rear Sproket Bolts
Does anyone have a few spare rear sproket bolts for a Firman? I torqued one to the point of breakage while changing the sproket and would like to have a couple spares. I could make some but don't have access to a machine shop.
If any of you Firman owners have torque specs it would be greatly appreciated if you shared them with me. My teammate and I are in the middle of an engine swap and they would be helpful. Obviously, engine torque specs are included in the engine manual. Thanks.
You may want to call HP-Tech Motorsports in FL or McLaughlin Motorsports in Indy, as they are Firman dealers and may very well have what you're looking for.
Not sure what diff you have, but WRD Williams Racing Developments in NC may have what you're looking for as well.
It's very important to use brand new jet nuts on those sprocket bolts each time.
I have reused very small jetnuts on things like sidepod to floor connections and they still have some "bite" after a few uses, but the sprocket bolt securing nuts are way too important to attempt reuse, and in fact have absolutely ZERO bite after one usage!
The torque numbers are just like everything else out there, ie 8mm is somewhere around 25-30 lb/ft. If you are tightening this nut to almost snapping the bolt, well, you'll go to "Knucklesville" soon enough!
On the chassis I've never been one to use a torque wrench on anything more than wheel nuts.
The bolts are definitely RFR specific, I don't see anyone but a RFR dealer having them.
I just ordered a Qty 50 - 8x1.25 jet nuts from Pegasus for about 1.59 ea or thereabouts, suggest all RFR owners do the same.
How's the car coming?
You've piqued my interest. What's special about them?Originally Posted by glenn cooper
On my HRP diff (Honda-based) I needed metric, "backwards" threads and a slightly longer length than I could get from Honda. Gary Hickman at Edge made some for me. The price and turnaround were pretty good.
Got it, thanks to everyone for their contributions. I will put up another thread regarding the engine swap.
You can call Nicholas belling at firman west cars 604 805 6201
Which Jon so kindly forgot to mention us as a dealer. We just happen to have a spare set in our inventory. It is very important that after the first and second session you check the tightness of these bolts as they need time to seat and can bak off. Once it looks like they are holding continue to check them at minimum once a day depending on how many sessions you run. As for torque it depends what kind of an ape you are with a ratchet but use a 10 mm t handle Allen and let it but up to the frame member and on the other side I use a snap on 1/4 flex ratchet 10mm deep socket and tighten as much as I can. It is also very important to ame sure the threads on bolt and nut are clean of oil grease etc as that will allow you to over torque more easily
Thanks for the info Alex! I couldn't get through to Nicholas, but Bill McLaughlin had some in stock and is sending them to me. I am an understudy of the "king of cheap" (Purple Frog) and couldn't help but wonder if I could find a machine shop to make them cheaper. To build on that, maybe find something stronger and perhaps lighter in the process. That might end up being an offseason project.
Well if at any time you can't get ahold of Nicholas then feel free to call me at 6046129507 and I can get you anything you need from firman west cars as well as Nicholas or Thomas Copeland
Da bolts
The bolts are 10mm allen head with a very long shouldered area. The head itself is milled down to afford the clearance necessary at that location as the carrier spins very close to the diff mounts.
Alex,
Sorry that I forgot to mention you as a dealer. I just figured that since he was located in the SE, the others were closer. My bad!
As Long as I made you feel guilty then my job is done
Bolts never "need time to seat." If these bolts loosen after initial tightening then there is a fundamental problem with the installation. If properly installed and tightened they will not back off. My guess is that you are using AN washers which, while very pretty, are not hardened and are crushing, thereby giving the appearance that these bolts have "backed off", especially since you advise . . . .
There is no reason to be without torque specs in these days of the smart phone. A free app will quickly show an 8mm/5/16-24 socket head grade 5 bolt should be torqued to 19 ft/lbs or 228 in/lbs. Torque wrenches are cheap now. No excuse not to use the proper settings on critical bolts.and tighten as much as I can.
I'll drag up an old thread that speaks to these issues. It's also entertaining . . .for some.
http://s2racing.yuku.com/reply/70/Ti...ction#reply-70
Last edited by Charles Warner; 09.26.11 at 12:22 PM.
Charlie Warner
fatto gatto racing
'Cause there's bugger-all down here on earth!
Given the application it is not feasible to get a torque wrench into the area. Hence why using a 1/4 inch ratchet, tighten as much as you can as you will never be able to over torque with the available leverage.
In that case, are you sure you are reaching the proper torque? You mention the bolts are "backing off." Something is wrong here.
Charlie Warner
fatto gatto racing
'Cause there's bugger-all down here on earth!
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