I guess Tom Bungay made it taller.Originally Posted by Racerex1
I guess Tom Bungay made it taller.
Wicked fast when the turbo came on boost. And that lovely chirp from the pop off valve. And fifth gear, when I realized I wasn't in it yet! Ahhhhh, good times.....
No, he (or someone) made it shorter. Best I can tell Craig had the stock bar, and sometime between he and I it got shortened drastically, but not properly, hence the splint. I am almost finished with the new bar, which is 6+ inches taller than when I got it. Best I can tell this is still a couple inches shorter than original, but it easily meets the gcr rules now. I'm sorry I have not been posting, I am very busy lately and trying to make it to pittrace for super tour next weekend. Will update when I have time.
PS. I would have loved to drive this with the turbo motor in it, I bet it was wicked!
Also I appreciate all the suggestions and discussion from you guys. I am not ignoring them and I do have various talking points regarding wing, fuel door, and etc. Now it is time for bed though, I need to finish welding out the cage tomorrow before work as my CWI is coming in the afternoon. (I am actually also a CWI but I stop short at inspecting my own welds)
The GCR isn't the end all for specifying the height of the roll bar. The broom stick test is. If you can't pass it with your helmet on you can't run. That's the main reason rollbars get changed.
The broomstick test is included in the gcr.... 9.4.5.A
I will type up a weekend report soon. In the meantime, I have a question I bet one of you guys can answer:
The axle shafts on the amac seem to be too short to allow a snap ring on the inboard CV joint. Neither of mine have one, and I was troubled by this, but assumed it was by design. Today I lost a race because one popped out of the CV.
Do you guys know if there is supposed to be a snap ring used and if so was there something that changed that might explain why mine was put together without them and appears to be too short to allow their use?
I have not taken it apart yet but at this point I am assuming I will be making new axle shafts that are a bit longer...
On a positive note, I believe I have set a new class record at pittrace today, so the car certainly has potential!
Normally we do not use clips on the inboard ends. Originally it had a locked/spool rear end and the car was later converted to a diff and its possible the diff is a bit narrower or offset to one side which may have used up some of that length. Or, the rear track may not be set properly and may be too wide. We have not seen this happen with the original setup.
I assume that you have single piece half shafts? Some cars had fabricated/splinted half shafts.
Thanks for the info!
That is very good to know on the clips but still something is off. Maybe it is the diff as you say.
I will tear it down and do some measuring once I dig out of the hole I put myself in at the shop getting ready for racing...
My axles are the fabricated ones, so updating to straight might be a good idea anyway.
Are these a part that you guys or someone has sitting on the shelf somewhere?
If not I have a good spline guy, I wonder if I should make extras?
Well, I do happen to have a few on the shelf I got as a package deal..... But I want to keep those. Normally in the recent past we had fast forward make them, but recent inquiries on them making more have seen prices get just a bit unreasonable, especially if you needed two different lengths, which I believe you would need. They're not the same length right and left even with the spool setup. You probably know this but one end is VW, the other is fiat, assuming that hasn't been changed since new.
If you do have them made i might be able to get a few more customers to spread the setup costs assuming they are lengths they need. There are a few racers near me that have wanted some spares.
OK, I finally have a few minutes for a quick update here. As you may have noticed, I got the car put together in time for the PittRace Super Tour last weekend. I didn't finish everything on my to-do list, but I did take care of a few things:
I finished the new (taller) main hoop and bracing. Got it inspected by a CWI, got an annual, all done.
Some of the welding was a little challenging...
I did manage to clean up a few odds and ends, including tie rod ends that were installed with a million stacked washers:
I had a great race weekend, but still had a few teething issues: Saturday I had a body clip that pulled loose from the fiberglass cost me a couple of laps, then the flatshifter adjustment vibrated so it thought I was upshifting all the time, and kept cutting ignition every time i topped a hill.
Still looked OK. You can see how hard my pit crew was working, and the other half of my crew just wanted to ride around with me:
I was turning pretty good lap times on Saturday despite the issues, so I was pretty excited for Sunday, and I was not disappointed!
Sadly I still did not win the race, as on the last lap my axle shaft popped loose. More discussion on that later...
washers
perhaps all those washers were for bump steer adjustment . were they on your steering rack rod ends to uprights?
I think you are correct. That is the only location on the car that we use that many washers. The washers adjust the height of the tie rod end in the steering arm bolted to the upright. Its not a location that we mess with very much so a lot of washers right there is no big deal. And the bump steer doesn't really change unless something gets bent.
^ There is no need to adjust bump steer once it is correctly set, and IMO, stacks of washers are never a safe option.
Anyway, back to my race weekend, as mentioned I had an axle shaft pop out of the inboard CV joint. Here is the shaft. If you look close you can see that the small section of spline outside of the snap ring groove on the inboard end has been stripped. I think it pulled out far enough that this was all that was holding the torque, and it stripped both the shaft and the CV.
I pulled the ARB and shock on this corner and worked the wheel through its travel, and the axle ranges from 3/4" to 1 1/8" too short.
I am working on getting some new axle shafts made now. These will most likely be one piece 8620 steel shafts, gun drilled and case hardened after machining. My current LH shaft is 13 5/8" long, so the new one will be 14 3/16". I will find some time this week to pull the other side and measure it as well.
Ted if you know of anyone who wants some, please ask them to get in touch with me and I will be happy to have them all made at the same time. I can make them whatever length even if they are different than mine. I should have a rough idea on cost in a couple of days.
I am considering trying to make it to one race in October, so will keep rolling on the car. As of right now the to-do list includes (in no particular order):
- adjust/repair flatshifter
- new axle shafts
- improved chain adjustment mechanism
- new (higher strength) chain and sprockets
- new diffuser
- dive planes in front
- camera and lap timer mounts
- new wiring harness
A couple of side notes from this weekend also:
The car felt pretty fast and judging by my lap times I think it will be very competitive once it is finished, especially since I have never put new tires on it and the ones I was using are at least 2 years old. That said, there is always room for improvement, and I have a few little things I would like your guys' input on:
1) I was having a problem with the car pushing in medium speed turns. I believe that this is an aero problem, and am planning to add dive planes to the front for a bit more downforce. Has anyone done this on an AMAC and what was your experience?
2) I am using swepco moly chain lube. I noticed that at the end of a long session it appears to all have burned/boiled off. I am setting the chain to approx 1/2" of slack in the middle. Has anyone had issues with chain temperature? I am wondering if I should put a NACA duct under the car and try to aim some cold air at the chain?
3) Is everyone using aluminum rear sprockets, and if so what kind of life do you see? Mine came with the car, but looked pretty good when I got it, and after approximately 200 total race miles it is shot now. This could be due to the chain stretching though as I have had to retension the chain after every session.
Thanks for any input!
Yes on the Aluminum rear sprockets. I always had them anodized as well since it seemed to preserve life a bit better. I could not see any signs of unusual wear on the sprocket but could not see all of it. Sprocket alignment is critical both to be in the same plane and then without any cocking between the two. I have good wear out of the Sprocket Specialists sprockets. There may still be an account for the AMAC under my name.
Although the engine sprocket is steel, it can wear out.
If the Flatshifter is working, it tends to lesson chain stress during shifting. If it is not working and you are shifting without the clutch or lifting a bit, the chain gets stressed/shock loaded during shifting and tends to stretch faster. I use a DID 530 ZVMX Gold X'Ring chain. It will do an initial stretch and then settle down. Some people change chains every 4 weekends.
Putting a new chain on worn sprockets will only serve to wear out the chain faster.
I have been using Chain Wax. I have not found any chain lube that does not get thrown off a bit. Have not had any burned off.
I did not experience pushing in slower speed turns. Check body rake, springs, caster, shocks. I do not know how long it has been since the shocks were serviced. RE Suspensions Inc just serviced my Ohlins and recommend servicing every 20-24 races. My notes are in the notebook I left with the car. I do not know what set-up Tom put on the car.
Craig Farr
Stohr WF1 P2
Big negative ghost rider. Quite a few on the west coast with Amacs that don't have a diff use a steel rear sprocket. I know, because I machine them from blanks.
We use various chain lubricants. Tri-flow, chain wax, chain kote. The main thing is to lubricate it right after a session when it is still warm and then wipe down the excess. For tensioning I rotate the wheels in the forward direction and wiggle the top of the chain. It should move up and down about a chain thickness each way from neutral. It needs to be checked in multiple places as some links are stiffer than others. At this time you can inspect each pin to make sure the o-ring is present, and rollers haven't started to split. Obviously if either condition exists the chain is done.
We don't have a chain overheating condition that I'm aware of.
Axles and stuff
What we did on my car was make a spacer for the right side to have equal length axles and then only one spare was required.
We tried various ways to develop downforce for the front and before we made the wing style front splitter we found a properly built NACA duct (to the their exact measurements, sharp edges etc) facing the ground with the large opening rearward and the shallow end about 4 inches in from the farther most front edge of splitter worked very well. We also redesigned the nose frame to support the nose all the way to the front edge of the bodywork. Below is one of the early prototypes that is in my trash pile not yet to the dump.
When the car was converted to a true flat bottom with no rear diffusers the rake that worked was 0.400, The best thing you can do is buy or build a front wing diffuser that was the real solution.
David
And that effort required changing quite a few things up front, with major modifications to the nose frame and nose bodywork.
Minor update:
I have had an extremely busy winter and no time to work on the car.
That said I made a pair of new axles, made some lightened CVs, and a CV spacer for the left side. All told it saves 2lbs per side and should eliminate the short axle issue.
I will post pictures some day when I have time.
I have also been working on a few other issues. I was hoping to start racing at VIR in a couple weeks but my wife is working so I can't make it. So the first race on the new setup will be the Pittrace super tour at the end of the month.
Similarly I don't think I have time to make a new splitter as you guys have suggested, so I do have one question: I want to add dive planes to the front of the car similar to what people use on Radicals. Like this: http://the-arc-angels.co.uk/shop/ind...product_id=304
I don't have time to make them and I figure the Radical ones will be close enough that I can make them fit. Does anyone know of someone in the US that makes or carries these?
Thanks,
Pat
dive plates
Hello Pat
Try Mike Devins at HRP racing products in Michigan he made me 2
sets for my WEST AND MYGALE 586-623-3055
Good to meet you this past weekend and almost kinda race with ya! Hopefully it'll be a little more enjoyable for us both next time... maybe a little more time to share a beer...
Nice to meet you as well Vaughan!
Sorry all I realized it has been months and I have not updated this....
I had a pretty good weekend at PittRace in May. We had several guys in P2 and I had a great time talking and racing with everyone. The car ran well, and several of the persistent issues seem to be resolved.
1) I sent off the flatshifter to Richard at RillTech and he got it all repaired and tested for me. It still wasn't working and I finally figured out that someone had wired the load cell backwards! Fixed this Friday during qualifying with a couple of great results: The flatshifter now works, and the chain wear seems to be much reduced.
2) New axles seem to be all good with no issues
3) I raced on the same tires I used last year, and with worse weather and 40lbs overweight (mostly on me not the car), I was still turning consistent times within a second of my lap record. I think with a new set of tires and a diet this thing is going to be even faster.
4) I added a turndown after getting sound flagged last year, and now am a couple dB below the limit.
Saturday the car was running great and I was having a great time battling it out with Bill Niemeyer, and looked set for the win and then, embarrasingly, I ran out of gas. Chalk that one up to pure stupidity on my part.
Sunday went a bit better and I had another great race with Bill, unfortunately he had a mechanical so I ended up winning without having to fight too had.
I still had some front end aero issues, and I think the car is pretty draggy top end as well. I have a plan for this but as usual I am way too busy to focus on racing. I think I will still do the PittRace regionals in a month or so, and maybe something in the fall.
Sorry I cant remember my password for the photo hosting site. I will post more once I figure it out.
Question for you AMAC guys:
There is a lot of droop in the rear suspension on my car and it happens to be right in the way of where the diffuser should be. The one that came with the car turned out to be illegal for P2 and also I think it had so may compromises it probably hurt more than it helped anyway.
I am hoping to race a lot more and make it to the runoffs next year, so I am redoing the whole bottom of the car to ensure legality and hopefully fix many of the aero issues. I have everything figured out (I think), except how to make the diffuser work with all the crap in the way.
Did anyone run a P2 legal diffuser and if so, did you modify the rear suspension to allow clearance?
Flooring
HI Pat I have a rear diffuser i took off my WEST when we where able to go to tunnels, it goes from the roll bar back and with the rule change in P2 to go back to this design i think it is legal again??? let me know if you think it would help i will make you a deal. You bought my FC diffuser when i went to FB, speedmandave@outlook.com
AMAC rear Diffuser
With regard to rear droop, what is the concern? These cars work better the more the roll is reduced, it needs to be under 1deg/g, don't know how much a Stohr has.
For 2014 Runoffs I ran a rear diffuser that was P2 compliant. The rear lower A arm goes through the diffuser, no real choice. My car (now Eric O'Brien's) had the pushrod suspension and one reason was to make more room for a rear diffuser. These are not great pictures but I didn't take many at the time, too busy working.
Admittedly the 2014 Runoffs did not go as well as I had planned and never really go the platform working well, would have finished 4th but for a flat 2 laps from the end and got a 5th.
After Runoff took the diffuser off and it has not gone back on yet. Eric has done an outstanding job getting the car sorted and we will soon add the diffuser back into the mix.
David
This is the Tunnel/Diffuser we were well into fabrication in 2013 when DSR CSR S2000 were combined.
Edit: P2 diffuser may not start before the leading edge of the rear tire.
Hi David,
Can you elaborate about the rule change? This is the first I have heard and didn't see anything in SCCA bulletins.
Send me a pic of the diffueser. I doubt it will work on the AMAC but I might be able to get something useful from it.
This is my concern. If I start the diffuser at the front of the tire as required, there is no way to make it pass below the lower control arm unless I add limiting straps for basically zero droop. IMO I will lose considerable mechanical grip if I do that. The only other option I can see is for the front of the diffuser to have a considerable upward step where it starts, and put the diffuser above the control arm. I guess that might be OK for downforce but probably not great for drag.
Otherwise I would have to either leave it off or completely redesign the upright and lower control arm. IMO the diffuser is one of the most important aero parts of the car so I am not crazy about running without one.
Diffuser
HI Pat
Back in the day 2006 my NEW WEST came with the floor that the diffuser tunnels could not start in front of the wheels,
then SCCA let us add real tunnels and we had one made and ran in CSR and DSR and won national championships in both classes
then SCCA said DSR was to fast and unsafe so that is when you see the current diffuser rule, i sold my car back to WEST because
we won 2 championships in CSR AND DSR with the tunnel floor and they wanted the car back.
email me and i will respond to you with pictures
P2 Diffuser
Actually P2 has had that wording since the beginning. It was in the 2014 January GCR 9.1.8.C.2.E.1 Aerodynamics
A rear diffuser is permitted beginning behind the front edge of the rear tires. The diffuser may be divided internally into multiple sections. The width of the diffuser, as measured inside the diffuser sides, shall not exceed the width between the rear tires in any lateral section of the diffuser. Strakes within the diffuser are allowed.
Many people have used the 1 in manufacturing allowance to creep into the area in front of the tire. I'm in favor of a STRICT prohibition of this as a tortured interpretation of the rules.
There is no way with the AMAC rear uprights to have the diffuser go below the lower A-arm, that is why in the pictures I posted the diffuser is above the A-Arm.
All race cars are just a series of compromises and hopefully all the ones you make produce a car that is superior to the other cars compromises.
On our AMAC the rear droop is limited to 0.375in, that is easy to control with the push rods. If you are interested in using the push rod design PM me and we can take the discussion off line to email and real phone calls, same goes if you or anyone else wish to have more discussion easier done in real time.
Dave Oleary: I would like to correct something you said about SCCA's position on DSR/CSR speed and safety. DSR/CSR participation had been steadily falling off and DRS had become faster than CSR and the BoD in it's infinite wisdom decided that only one Sport Racing category was necessary mandated the combining of DSR and CSR, the CRB and FSRAC pushed back and a compromise was reached and DSR/CSR/S2000 were redesigned into P1/P2. The top speed envelope for P1 is within a second of where DSR was in 2013, both the P1 and P2 ad hoc committee's worked on a targeted power formula that defined the P2 to P1 lap time differential. Safety was not a factor in equation, the primary factor for P1 was the power made by a fully built 2008 GSXR in a car weighing 1000lb. With the exception of Scott Tucker lap times at RA were close to 2:00 and still are.
What year/s did you win CSR/DSR with a West? The only West I could find that won was Scott Tucker in a West in 2012.
David
Last edited by sccadsr31; 07.17.21 at 11:01 PM.
HI David
I was the NORTHEAST DIVISION NATIONAL CHAMPION in both classes in my WEST and P2 NORTHEAST CONFERENCE CHAMPION in 2017 in my MYGALE
NOT RUNOFF NATIONAL CHAMPION ALTHOUGH WE TRIED...
Ok guys, I have a couple of events under my belt since I last posted here. I didn't have a great time at Road Atlanta, but did OK (5/7 saturday, 4/7 sunday). I was in better form this past weekend at Summit Point (0.9s off the lap record with 85F temps), but nobody else showed up for me to race against. I promise I will upload some more pictures and build updates soon!
In the meantime, I am hoping someone can help me out with a couple of AMAC questions:
I just purchased most of the parts from the James AMAC from John R here on Apex. One reason I did this was a need for more wheels. Unfortunately, the front wheels from that car won't work on my car. They fit the hubs and main body fine, but the front body cover won't even come close to fitting on the car. My car uses a 7" wheel with 1" outer wheel half, and the James wheels are 8" with 2" outer shells. Do any of you AMAC guys know if there was a different front nose on that car or something that allowed the wider fronts? I looked at flaring my front body half but it seems like it would be a major project possibly beyond my fiberglass skills.
EDIT: nevermind, I found some old pictures of the James' car; it has a totally different body than mine.
Second question:
I am probably going to switch to a 22x9 rear tire, anyone know if there will be any major fitment issues with those?
Just in general how much difference was there between these cars from one to the next?
If one of you guys who knows a lot about these cars would prefer to just give me a call that would also be much appreciated!
(304) 5four2 5eight23
Last edited by patman; 04.25.22 at 4:06 PM.
The car as run by Ted and Nancy James was very different than all the other Amacs produced. As you discovered, that bodywork was not Amac at all. It was actually a March body that they had the molds for. It was much wider than the original AM6 and later AM7 bodywork.
I don't know about fitment issues with the AM7 body. Paul Decker runs 22" rears on my old AM6. Dave can probably tell you why you shouldn't run the larger tires. The geometry was designed around a 20" tire so ride heights will be somewhat jacked up. Obviously gearing will change too.
There really were no major differences other than the different bodywork. Some additional tubes were added to the chassis, and eventually the chassis were made almost entirely of 4130. Wall thicknesses were increased in areas we saw cracks developing, mainly in the rear bulkhead and engine bay. The first cars had parallel links in the back and we later switched to A-arms as the framework for the parallel links liked to crack. A lot.
Did you get the fuel cell from John?
Pat - From what I recall, a 22 inch rear tire would not fit within the rear bodywork and diffuser structure. The difference in speed between a 20 vs 22 rear tire is about ~12mph (12000rpm 08 GSXR) faster.
Craig Farr
Stohr WF1 P2
Ted: yes I have the fuel cell.
All: I found a pair of old Hoosier 22x9-13s and put them on today. No major fitment issues. One small bracket will have to be cut off and rewelded tomorrow, and I might need very slight clearancing at the rear wheel arches.
Gearing is no big deal, -1 tooth front +1 rear will put me right where I need to be.
I also have solved the chain adjustment problem but won't have time to implement until after this race. I'll post some pictures next week.
Sent you a PM
Ok, time for an update. Sorry it took so long.
Remembering back to the axle issue, I ended up making new gun drilled axles which are both the same length, and a spacer for the LH side.
While I was at it I bought some new CV joints and lightened them. The complete assembly is over 2 lbs lighter than before (and won't fall out)
Next on the to-do list was a new diffuser. When I started on that, I realized that the original side pod undertrays were just shy of 1" above the center section by design, and after 20 years of duty there was no way they were passing the flat bottom rule. So I replaced pretty much the whole floor:
In the front there was a lot of open space, so I made new side floors:
Some of this required bending tabs that couldn't be done in the brake, so I made a high quality tool. So far SnapOn has not called me for the rights to it, but I am ready when they do:
As discussed here, on this car the diffuser is a challenge. I ended up going over the lower control arm and have a complicated slot/seal arrangement around the trailing link. I am not 100% happy with the result, but it does seem to be more efficient than the old one and is 100% legal, which was the goal:
I made several other small changes over the winter, including a new fuel test port since I got griped at about the old one. I was pretty excited for Road Atlanta this spring, but between not knowing the track, the bad weather, and whatever other excuses I can think of, I didn't do super great there, although at least I didn't crash like a lot of other people. I am going to blame most of this on my inattentive pit crew, and also my shop mechanic who thinks whoever has the biggest wrench wins:
After that, I went to Summit Point Majors with no real changes besides some maintenance and minor tweaks. Sadly, there was no one there to race with, but I was less than a second off the P2 lap record on an 85F day, so I was satisfied with the car. Annoyingly, I got sound flagged again at Summit, so I machined up a lightweight V-band setup for configurable exhaust tips:
In that pic you can also see my new and improved wing stabilizer. This was always part of the plan but I just never had time to fab one up until now
The other big change for Pittsburgh was the switch to Goodyear tires. The old tires were working OK for me, but I just never got treated super well, so I decided to give something else a try, which so far has been working super great for me. Goodyear have been great to work with, and the tires are a bit faster but also surprisingly over 10lbs a set lighter! Plus they look nice:
Between all these tweaks, I ended up setting a new lap record over 3 seconds faster than the old one!
I hate to admit this, but even at this pace, I ended up second again, because I ran out of gas again. I know, I am a moron. I had a good time otherwise though:
Sunday at Pittrace it rained, and due to various circumstances, I had to race on slicks. If anyone is ever tempted to do this, I wouldn't recommend it, it was incredibly difficult just to get the car back in one piece and stay out of everyone else's way. I was told by one of the stewards afterwards that I got the "Dumbass Award" for the day.
I am currently working on several more pretty good upgrades to the car, and will try to update this a bit more often in the future. I do also have another project going which I am doing pretty much by myself, so we'll see how much time I have, but so far my feminine overlord has been extremely generous with regard to racing so I maintain high hopes.
A few things from last weekend at Watkins Glen HST:
1) The new chain adjusting system worked great! Took a sprocket change from a 60 minute ordeal to a 10 minute job. I will post pictures later.
2) I continue to be happy with the Goodyears, I ran Hoosiers for practice and qualifying and picked up about 2 seconds after switching to the GY.
3) Race recap- Saturday I started at the back of P2, but due to my desire to avoid a huge pileup in turn 1 and trying not to hold anyone up, ended up with 6 or 7 FC/FE between me and Bill after lap 1. It took me about 5 or 6 laps to pass them all, by which time Armen had some engine problems, and Bill was out of sight. Still I ran as hard as I could and eventually caught him. I passed Bill coming out of the boot, and then got the white flag. Stayed well in front until the straight after the boot, where I braked early to let an FA by. This turned out to be a huge mistake and I spent 2 turns avoiding the FA, by which time I was way off pace and Bill snuck by me on the inside in turn 10. I was pretty disappointed as I worked super hard for the lead, but I always have close races with Bill and I knew if I gave him an opening he would be past me. Next time I will not be letting anyone get in my way when I am in a tight race.
Sunday I was racing by myself as both other P2s had mechanical issues. I was taking it kind of easy but not too slow. A few laps in a felt something funny in the front end, but it seemed to go away so I sped back up. On lap 7 (needed to finish 7 laps for points), I went into the esses and the car just went away at 118MPH. Turns out my steering arm broke off the upright on the front left. It appears that 2 of the 3 bolts show some fretting, so I am guessing they broke one at a time. Possibly also due to some hard curbing I did on Saturday. Fortunately I kept it out of the wall (barely!) so not a perfect end to the weekend, but I'll take it.
I have not had time to organize photos, but here are videos!
https://youtu.be/gG4QUNbLsMI (saturday)
https://youtu.be/s-AOKDp6cZ8 (sunday)
Skip ahead to about 15:30 on Sunday video to see the exciting part.
Pat, sounds like a successful weekend despite the steering arm issues. Two things on that failure: first, it has happened before as the steering arm tube wall gets fairly thin out where the single button head screws into the upright and cracks start to form there, so one of our pre/post race checks is to put a finger between the steering arm and backside of the brake rotor and while on the ground wiggle the steering wheel. If you feel any movement investigate further. Second, some of us have redrilled the upright and steering arm for 5/16-18 hardware, or at least put helicoils in the upright.
Did you run the .065 bars?
Ok, I finally have a few minutes to add to this.
First off is some info on vastly improved (IMO) chain adjustment.
The old turnbuckle system would take me over an hour to do a sprocket change, and 15+ minutes just to adjust the chain. Looking at this system, it is evident that the pinch bolt is really all that is required to actually hold the differential in place and thus fix the chain tension. Using turnbuckles for adjustment is then unnecessarily complex and cumbersome.
As such, I decided to cut it all off and start over!
Here are the new parts. Note the 8-point holes are for 3/8" square drive tools for adjustment:
New upper mounts:
And the finished system:
I know it's a little hard to see in the pictures, but adjustment is as simple as: loosen the pinch bolt, use a 3/8 ratchet or breaker bar to rotate the cam for desired tension, then tighten the pinch bolt. Huge improvement! Has been through several races now with no issues.
I have more to come including runoffs recap, I am trying to make time for this sort of thing this week while it is rainy!
Sneak preview:
Goodyear offers bias ply and radial tires for sports racers. The radials are purported to be ~2s faster. Also there is some availability for poor guys like me to get good scrubs from P1 drivers, which is a pretty big deal on my budget. The problem is they are bigger.
Here is the difference:
I think you can see where this is going, and yes, it involves a sawzall....
Ok, moving on. I decided that I didn't want to go the the Runoffs with bias tires. I have very little time for working on the car this year, but I couldn't make peace with the idea that I was leaving a bunch of known time on the table. After a bunch of measuring, it became clear that the radials would never fit under the existing body work. So I decided to make them fit.
First step was widening the front suspension. I only needed a little bit as I also had to switch out wheel halves. I don't have any pictures but I just made new front lower control arms. No big deal. While I was at it, I replaced front wheel bearings and modified the uprights for larger diameter bolts at the steering arm to hopefully eliminate any chance of a repeat of Watkins Glen.
Once the suspension, wheels, and tires were all modified and installed, I was able to take measurements and determine what I needed to do. Step one looked like this:
Then first layer of glass on the back. This was my first time adding into the middle of a fiberglass part, but I think my plan worked out nicely:
And after curing, turn over and start on the front:
I used some thick mat and tiger hair to fill in the crack, then put a layer of glass on the front. This was my spare nose, and as you can see, it needed some TLC anyway.
Once that was done, I clamped it to the center section, cut the center, and blended it in. I also added some side vents to improve front downforce:
Similar process in the rear, although a lot simpler. I could have actually made the rear tires fit, but I wanted the hourglass shape and I didn't want to narrow the rear track.
Next up was a bunch of sheet metal work, Including a whole new front floor, front bulkhead, side vents, and front splitter Note the master paintwork on the splitter, my son (7) was hanging around the shop and really wanted to paint something..
Now the finished product. I wasn't quite satisfied with the finish quality, but I started on this 9/14, and the showed up at the Runoffs on 9/25, and still had to work several of those days, so all in all not bad (note these were taken mid-week at the runoffs and as you can see, testing and qualifying wasn't kind to my shiny new splitter, among other things. More details later.
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