Author Topic: Gordon kit for road race frame? (Read 3309 times)

gschuld · « **on:** July 16, 2015, 07:22:57 PM »

So I am preparing a bare cb750 K0 frame for a road racer. I was wondering whether putting a Gordon frame kit would be a benefit or not. Clearly, it would make light engine work a ton easier, but as I am also going to do some stripping of extraneous materials and some gusseting, would the Gordon kit be heading down the wrong path with frame stiffness? I don't recall any road racers using the kit, perhaps I missed it.

George

Old Scrambler · « **Reply #1 on:** July 17, 2015, 06:28:41 AM »

One or more of the sanctioning groups may not allow it. Personally, I think you would be adding some hinges to the frame

If rules allow, why not insert replacement frame-members that emulate the CB750A design? Or just get a CB750A frame to begin the project.

bwaller · « **Reply #2 on:** July 17, 2015, 08:07:01 AM »

I agree. Redesign that section to copy the auto. I doubt a race assn would kick at all, but full tubing is best on the track.

gschuld · « **Reply #3 on:** July 17, 2015, 08:45:36 AM »

Yeah, I agree that full tubing is best. I just removed a motor from it's frame last night and man what a frustrating deal that is in general, never mind when all you need to do is inspect or modify the top end of the motor.

I imagine the cb750a bent tube upper frame rail style would make fitting the factory tank impossible as the tank bottom would likely hit the raised frame rails. Bummer. This would require a custom tank, not ideal.

George

teebee67 · « **Reply #4 on:** July 17, 2015, 08:47:45 AM »

Isn't the CB750A too late for UK racing (end of 1972 is the cut off date), what is the cut off date in the USA?

gschuld · « **Reply #5 on:** July 17, 2015, 09:39:43 AM »

We have several separate vintage associations here in the US and Canada. In the USCRA for example 1972 is the cutoff in HWSV class, but all cb750 sohc models through 1978 are specifically allowed. I assume that the auto is not included in this exemption. Other associations have their own deal... so others may know.

George

Old Scrambler · « **Reply #6 on:** July 17, 2015, 10:14:11 AM »

Sooooo..........I grabbed an early K-tank and walked to my shed and trial-fitted the tank to a CB750A frame...............the lower rails are about a half-inch too wide for clearance. The inner shoulders of the tank-bottom would have to be 'crushed' to get the required clearance. The length of the crush would be about 5-inches and the height would be about 2-inches to assure all-around clearance. That would be about a pint-sized area on each side so maybe a 1/4-gallon of fuel capacity would be lost. Not hard to mod with 'cut & weld' or a press and some hammer strokes.Most race tanks are something less than perfect to begin with, and this type of mod would be out-of-sight.......................you could claim you have a WRINKLE tank

teebee67 · « **Reply #7 on:** July 17, 2015, 11:46:01 AM »

I have fitted one of the "Gordon" type kits to my race bike but not raced it with the kit fitted yet - we shall see!!!

gschuld · « **Reply #8 on:** July 17, 2015, 12:07:38 PM »

Old Scrambler,

That's about what I had expected. Thanks for checking. No ideal solutions it seems, but some options with varying levels of inconvenience associated with them. If I needed a custom tank anyway, I'd head down the dark path toward more significant frame modifications. I'm trying to avoid the nuclear approach with a first attempt at road racing.

George

MCRider · « **Reply #9 on:** July 17, 2015, 12:18:03 PM »

Quote from: teebee67 on July 17, 2015, 11:46:01 AM

I have fitted one of the "Gordon" type kits to my race bike but not raced it with the kit fitted yet - we shall see!!!

Back in the day, ca 1978-80, I had an APE frame kit (still do) on my CB750 I was then racing in WERA events. It was not nearly as robust as a Gordon Kit. More like a Carpy kit of today. Rode it in several 4 hr Endurance races and many sprint races.

Granted maybe not the ideal, but we were young and carefree. It and any of its possible side effects were way down my list of worries.

johno · « **Reply #10 on:** July 18, 2015, 01:34:55 AM »

If the Gordon kit is well fitted it will actually stiffen the bottom tube , not weaken it . If you dont believe me go and find a length of tube and put a solid slug in the middle and then do a bend test in a vice comparing plain tube and then tube with slug in middle, just use a dial gauge and scales.........This is what I done as I thought it would weaken the frame , after the test I realised I was wrong so I put one on my race bike coas its better than standard

johno

Sam Green Racing · « **Reply #11 on:** July 18, 2015, 01:49:25 AM »

Just a thought for anyone going the Automatic route, if you are using a K motor, be sure to use the K swingarm.

Sam.

voxonda · « **Reply #12 on:** July 18, 2015, 06:13:12 AM »

Raced for years with the Gordon kit. Better than stock tubes. Period! Look at how MV Agusta did it for all those years , exactly the same type of connection between the tubes. BTW a much better job then what Honda did with the DOHC frames.

gschuld · « **Reply #13 on:** July 18, 2015, 08:46:54 AM »

interesting. Good to know Rob.

Does anyone know which vintage road racing organizations allow or ban Gordon frame kits? USCRA, VRRA, and AHRMA specifically.

I'd really like to be able to get to the top end with the motor in the frame, plus have the option to run a stock fuel tank if possible. The Gordon kit will allow that.

George

gschuld · « **Reply #14 on:** July 18, 2015, 10:34:44 AM »

I put in a call(voicemail message) to a cb750 owner/racer USCRA tech inspector I know about whether Gordon Kits are OK in their series. Also, Brent Waller is at the races in Grand Bend and should be able to find out for sure whether they are allowed in VRRA.

Just left a message with Carl Anderson, the main contact for rules questions for the road racing classes at AHRMA.

Rob, if you are confident that the Gordon kit is an improvement over stock for a road racer, that's good enough for me

As long as the sanctioning bodies allow the Gordon kits, I will order a pair right away. Such a maintenance restriction on the motor with the stock frame really bothers me with a high performance motor/bike.

George

Old Scrambler · « **Reply #15 on:** July 18, 2015, 12:44:16 PM »

Livin' & Learnin'..............I love this board

gschuld · « **Reply #16 on:** July 18, 2015, 01:21:05 PM »

Just got word back from USCRA rules tech. No problem with "Gordon" style frame kits in HWSV. Just AHMRA and VRRA to go.

George

754 · « **Reply #17 on:** July 18, 2015, 01:28:56 PM »

I would like to do a stiffness. Test between mine and the Gordon kit....
I think mine may be stiffer.. I know it's about 2.5 - 3 lbs lighter...... And nobody likes adding weight unless it's to aid traction..

gschuld · « **Reply #18 on:** July 18, 2015, 02:08:12 PM »

754,

2-3 lbs lighter? That's a lot of weight my friend...

Could you refresh my memory regarding your frame kits? Availability, price? I may be in the market very soon.

George

gschuld · « **Reply #19 on:** July 18, 2015, 06:50:51 PM »

Just got a call back from Carl Anderson, the main rules guy from AHRMA. He said that the Gordon style frame kit would be legal in Sportsman, Formula, and Superbike. Basically everything expect Historic Notice Production that requires a totally unmodified stock frame.

So the frame kit is allowed in USCRA Heavyweight Supervintage, And AHMRA Sportsman, Formula, and Superbike. Waiting to hear back from BWaller regarding VRRA.

George

Retro Rocket · « **Reply #20 on:** July 19, 2015, 01:01:40 AM »

Quote from: gschuld on July 18, 2015, 06:50:51 PM

Just got a call back from Carl Anderson, the main rules guy from AHRMA. He said that the Gordon style frame kit would be legal in Sportsman, Formula, and Superbike. Basically everything expect Historic Notice Production that requires a totally unmodified stock frame.

So the frame kit is allowed in USCRA Heavyweight Supervintage, And AHMRA Sportsman, Formula, and Superbike. Waiting to hear back from BWaller regarding VRRA.

George

I can't see it being a problem in the VRRA, Brents frame is far from stock....

PeWe · « **Reply #21 on:** July 19, 2015, 01:40:21 AM »

No news for you guys...
Frame kit is a must on a modified street bike.
I have had good use of it 8 times in 16 months.
Restored head, replaced all cyl studs, changed cam timing, changed cam. Used 4 different cams. Replaced valve cover. Easier when I replaced the carbs. Repaired cam stud threads in head twice... Retorque head nuts not complicated either.
EDIT: Adjust valve lash easier with valve cover off and see when rocker arms are on the base circle. Threads in valve cover might need to get new threads as well. A race head might have all threads helicoiled from the beginning...

I'll have use for it coming winter when I'll open the engine, change crank, rods and trans. I'll remove head and cyl block in frame before taking out the engine. Maybe same reverse order too. I'm not sure which cyl going back in. Current 836, my old "900" or something else....

Coils not needed to be removed when changing/timing cam only. I mount the dial indicator in frame when I time the cam. Small degree wheel mounted on ign side. Pamco/Dyna-S ign not needed to be removed either. Rotate engine with no plugs need not much force so I use the 23mm nut on ign side. Point plate however, need to be removed and hanging outside in its harness. Points have to much stickout

bwaller · « **Reply #22 on:** July 19, 2015, 05:43:28 AM »

Frame kit a.o.k. with VRRA tech, so is the more modern Davies fairing. They just don't want to see a 90's sport bike fairing grafted to a 70's motorcycle.

gschuld · « **Reply #23 on:** July 19, 2015, 05:56:42 AM »

Good deal with the frame kits. Thanks Brent! Good news regarding the more aero Davies fairing as well

So there you have it. "Gordon" style frame kits are legal in USCRA, AHMRA, and VRRA for those who want to install a set and go road racing...

George

Tintop · « **Reply #24 on:** July 19, 2015, 12:07:41 PM »

Quote from: bwaller on July 19, 2015, 05:43:28 AM

Frame kit a.o.k. with VRRA tech, so is the more modern Davies fairing. They just don't want to see a 90's sport bike fairing grafted to a 70's motorcycle.

Have you placed your order yet??

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Author Topic: Gordon kit for road race frame? (Read 3309 times)