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2000 forks- front wheel hits the radiator

4151 Views 17 Replies 9 Participants Last post by  Zenbiker
Radiator problems in over here in Germany. Last week my radiator had a leak. I sent it to a radiator builder, and he repaired it. It had a small crack at the rear - about two inches above the pulley. I'm just back from my garage (it's 2.40 am over here), and it's back in the bike now, and I'll test ride it tomorrow. I really hope it's not leaking any more. It shouldn't do, cause the radiator builder tested it under pressure- but you never know.
I ordered a new radiator at the factory, cause I don't really trust a repaired one. But it will not come in time for the European Bike Week, so I really hope the repaired one will make no trouble during the next 2 weeks.

My buddy Andy's front wheel/fender of his 2000 502 hits the fan if he ride a little too fast over a bump. The problem get worse if he additionaly brakes while riding over a bump. The fan hits the radiator, and it's producing a loud noise when the blades scratch the radiator. There's also a dented area about an inch in diameter in the center of the radiator where the fan engine hits the fins.

His weight is only 170 lbs- riding with two people is impossible...
Radiator, fan, fender is all stock.

We already extended the top pre-tension rod about 1", the radiator/crank pulley gap is only 1/4", the gap between front tire and fender is very tight, 20W fork oil .... the fender still hits the fan....

Someone else with this problem? What's the max length for these pre- tension rods we could work with? It's already hard to screw the top (fine thread) bolts in the fork tubes with the extended rods. I think we can't go much longer.

We don't know what else to do, and would appreciate every good advise.

Sauerkraut Loaf

PS: The radiator builder said we've got a high quality radiator in our bikes. He said such a high quality would be hard to find in europe. Seems like Ron Davis did a good job.
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Hi Olaf, The only thing I can think to do is add as much as you can, to the preload rod, and adjust the front fender as close as you can to the tire.
Hi Loaf,
may be the new style fender would make a small difference. I think its a little "thinner" than the old style. Hope you still have fun at the bike festival. :D
P.S. I am in Grand Haven, Michigan tonight. Could not make it to La Crosse, but may be next year.
Fender Hits Fan


I had this problem with my 2000 502. The crome front cover I got for the fan motor with a Boss Hoss logo (it mounted on top of the existing cover) made the fan motor stick out further to the front. In seems in 2000 they went with a different fan for the big block and the motor was "thicker". I took off the chrome cover and everything was fine.

The new fans have a chromed OEM cover rather than an "add on" cover over the top.

Could this be his problem?
Loaf...I once got a front end from the factory for my 2000 small block to replace inferior chroming. The bike seemed to ride lower and clunked when I hit a bump. When I checked, there were NO preload spacers and NO oil in the forks but the fender never hit the radiator. The fender shouldn't hit even when the forks are totally compressed. When did this start to happen with his bike. I assume it was OK at one time in the past.
Many thanks for all your replies.
Peter, what are you doing in Michigan? I thought you are on vacation in Canada..?.. Come back to Germany, soon. I know you've got one of the new style fenders laying around in your garage. Too bad that you can't make with us to the European Bike Week. I think Andy and I will have a lot of fun. :beer8: :beer2: :biker: :cop2:

Yes, I noticed the difference when I compared the fans of the bikes in my picture collection. When I ordered my chrome fan I told the factory I would like to have the old style with the chrome plated "Boss Hoss Cycles" cover. I thought they made the change for cost reasons :oops:
Andy's fan is one of the new style fan's with the chromed OEM cover, therefore that's not the problem - but it's good to know why they changed it.

Andy's fender hit the radiator - or better said the fan- from the beginning on. I was surprised when he told me about the problem, too- cause I never read something in the past about this problem in the internet boards.

You seem to found the key of the problem. We can't make the rod any longer, because otherwise we wouldn't be able to get the top-bolt in the threads, but there was a little too much gap between tire and fender. Andy had a tire/fender gap of 1.5", and we thought that would be tight. But I measured my bikes gap, and I have only 0.8" - I think this will solve Andy's problem.

Many thanks to you all,
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John & Loaf,

One thing to consider before you change the length of the tubes is the change to rake & trail.....and yes it does change it. If you have never ridden a bike with 0 or negative trail........make sure you grab a handful of super glue before you get on.........especially @ 1200+ # :D

I do not know what the current rake and trail measurements are on the Boss, but they can be calculated pretty easy........by the handling characteristics of the bike, they must be very close to neutral already because of the relatively light handling for its' weight.

I'm not a steering expert, but I fought this problem on a HD for 2 1/2 years and it had a "death wobble" that would literally twist the chassis under the tank and put the bike sideways at 100+........I finally disassembled the front end and sold it to another guy..........his bike had (has) the same wobble........look in JP Cycle website under tech and search for rake & trail. I believe they have the equation in there for calculating it as well.

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John...I noticed in your post that you believe the very stiff suspensions are cracking the frame. The funny thing is that my 2000 small block had the stiffest front end I've ever encountered. 300 lb. guys couldn't compress them at all and the machine was miserable to ride over the smallest bumps and expansion joints. After 16,000 miles of misery I decided to go to the inverted newer style front end which is MUCH more compliant and much more comfortable. By the way, not everyone has had this problem with the old style forks.
Interestingly after 10,000 miles with the new softer front end...the gusset cracked! Go figure. Just to say that the stiff front ends may not be related to the cracking problem....Joe
Okay, before somebody cuts my nads off, I looked at the calculator for the rake/trail, and lengthing the tubes will result in longer trail...better high speed handling......little worse at slow speeds......2" probably won't be felt slow, but could make a difference at high (100+) speeds.

Re: 2" over tubes

John Monticelli said:
Hi, Loaf,
I have found a source for 2" over stock tubes. This will let you reduce the preload, and have a nice soft ride with a little extra clearance to boot. This is something we have done on Harleys forever. I can't understand why, after discussing this with the factory, this option has not been available all along. They, instead, have taken other measures to combat the clearance problem, IE rake the neck, inverted front end(shorter, actually that the ones we have, as they have reduced the spring preload, and maintained the length), and changed the fender.
With a 2" over set of tubes, you can then drop the preload, which will give you about 1" of extra height, depending on how stiff you set up your springs. This is negligible, and will make the bike look and ride better, and provide extra ground clearance for the footpegs and pipes. All of this adds up to a safer machine.
Also, I think that the stiff ride is what is cracking the frames. It doesn't take a genious to visualize what is going on, here.
We are working up a price, which I feel will be very affordable, as all there is to the tubes is threading on one end, and a snap ring land on the other. This would be just too easy and cheap for the factory to offer, I guess. Still can't figure why they didn't know about this. Maybe they were afraid of getting the bike any higher, and making it harder to handle. That line of thinking has defeated itself and made the bike more expensive, which is probably what they really want............
Also, I have found that working on the front end, using a jack under the front, and various height blocks under the stand to stablize the bike, is very doable for the reasonably experienced mechanic to handle by himself. Have had mine apart twice to examine the problem and lube the triple tree bearings. Just like a Harley, only bigger. There is no reason why these front ends can't be a great performing unit if they are set up correctly.
Big John 8)
I like the idea of 2" over tubes. Andy couldn't test ride his 502 after the changes, because it's raining cats and dogs in Germany, but it seems to be better than before. We depart tomorrow - direction Austria. When we are back in two weeks we'll know more. If his fender still hits the fan while hard braking and riding over a big bump, then these 2" over forks tubes could be a great help for him. My forks are working perfect, but there's nothing wrong with a softer ride and 1" of extra height, therefore I would be interested, too. My rear end already has 1" extra height because my 265 rear tire has 29" of diameter, but I scratch the pegs in almost every curve. More ground clearance means more fun, and my legs are long enough to handle 10" of extra height :lol:
Please keep us informed about these tubes.

Isn't it possible that these 16000 miles of riding with your first, stiff fork made the preparatory work for the later crack/ the material weak?
Vibrations or poor material could be the reason for the cracked gusset - but what John said makes sense to me, too- the harder the ride, the more stress to the frame, and the higher the chance for a crack.

Hmmmm.....my God, a cracked steering head....what's next? I love this big "Tennessee Iron", but is there something really perfect on our bikes except the engine and maybe the drive belt? :cry:

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Loaf...I agree that the early stiff front end may have laid the stress scenario out for the later crack. As to what is perfect on these bikes...Aside from 2 trannies, a blown head gasket, melted fuse box and repeatedly failing rear master cylinders and now the cracked steering head gusset....everything is perfect on them!
Even with all the problems here and there with this bike, (and I've been pretty fortunate not to have had many) the smile this bike puts on my face every time I ride it makes it perfect to me!! :D :D :D
Well.......it does make me smile every time I ride it when it's not doing anything peculiar! Ha Ha!
Like I've always said, the dick heads that don't like or can't handle these bikes should sell 'em and buy a ****ing Harley or BMW. Quit your bitchin'

(Excuse my French)

2" tubes

I'm also interested in how you make out on these 2" tubes. I've had mine apart and tried to make some improvements. I reworked the green bushings as Carb Mike had done with his , and that helped. I measured the spring length, and rates, and pursued finding longer springs . I was trying to trade off some preload and use longer springs with a modified cap.
I tried a few spring companies and spoke with some one at Progressive Suspension . I ended up giving up dealing with all of them.
The dampening valve, if you want to call it that, has four 1/4" holes in it. I don't see it ever working unless its redesigned . These longer tubes could work out for me. I was planning on going inverted, but instead maybe I should go through the old ones again. As soon as I can get my bike into the garage, I'll measure a tube. I went for my first bike ride in 2 1/2 months on my wifes bike yesterday. It was great ! Jeff
I'm going to be pulling my front end apart this winter to have the lower legs rechromed and while I have it apart I will rebuild everything . I'd like to hear from you Jeff or anyone that has improvement Ideas so I can do the improvement to mine also while I'm in the process . Like I said , I like the idea of 2" longer tubes but I'd like to hear from someone who has tried and proven that this will be an improvement . I do think the Boss could use a little longer tube just for looks and road clearance.
the fender I have at home ist the old style, and I have to send it back to Rony. Sorry :cry:
Have fun in Austria :D
Grumpy...If this is not the place to talk about problems then what is? I think it's a "dickhead" that will accept any and all problems with the manufacture of these bikes and eat it all. Just my 2 cents...Joe
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