wheelbase difference

[rick]

Hi, it looks like I have 6mm (1/4") difference between lhs wheelbase and the rhs wheelbase, I can not (without cutting and welding) adjust the lower a-arm, question is will I notice 6mm on a street car that will not see any track-time at all ? or will I not notice this with the correct set up (caster/camber/toe..)

thanks, rick

 

[EGLITOM]

Hi Rick

you will probably notice nothing as long the other parameters are ok. Realy wonder if Caster can be the same than ? Just as a reference, try to measure old 911s up to even 94, they have siginificant differences, higher than the ones measured from you. Especially on true track running from front to rear.

Question would be where it comes from: is the rear running perpenticular to cars longitudenal axxis or the front or non of them. For example if the car got a hit on the left front, it could be that wheelbase is shorter on that side, but everything else is still ok ( caster ,camber) and toe in/out could have been corrected to still be ok.

So it would be interesting to find out what the reason is, but no i don´t think it will have a significant effect for your purpose.

TOM

 

[rick]

Hi Tom, it looks like I have 3mm at the front and 3mm at the rear. I still have to replace the rear bushes so maybe that will solve some of it.. caster at the front can be adjusted even if the wheelbase is not the same. I found a nice 38mm hole underneath the chassis that looks to be in the middle of all, measured from this hole the right front wheel seems to be 3mm out, well maybe i just cut it and weld it back to make it perfect.
thanks for the information, vielen grüßen, rick

 

[Bill Musarra]

Just having gotten my car on the road, I was interested in just this topic. So once on the ground and driving a little I took out the tape measure and long rail to check my inital settings of the beginnings of alignment. What I found was interesting. All tires were set to "dead level straight" as I call it. No toe or camber. Caster, who knows at this point. No tools much to get it. I had relied on an old post that DRB's needed 4º of caster and this is aproximated with my rudimentary tools(magnetic angle finder) til a professional can get to it. My rail was setup square with the frame rails and all measurements were done to get them straight, then level on the ground. I hadn't thought much about wheelbase until this thread cam up. So I measured and found one side was a good 1 1/2" off. I hadn't noticed anything amis while driving or taking a curve or two rather hard. What I did do was to get them lined up with the same distance from the front of the rear tires to the frame rail, as well as centered in the wheel well. Wasn't something you would really notice til you measure. Did notice that one rear had a slight rub mark about 3/4 of the way to the rear of the well. This told me it was too far back. The fronts are C-4 corvette units and there isn't much alignment you can do without a machine. Another "project to be done".

Bill

 

[EGLITOM]

Bill

interesting, if understood you correctly you measured from reference points on the frame and still got a difference of 1,5" ? Or did i missunderstand something?

Adjustment of suspension settings has been the first thing i did on my build and this included the wheelbase setting as well. Everything else ( bodywork) has to made fit that afterwards. I strongly recommand this order for every new build ( it is somehow a different scope in a rebuilt like yours).
http://www.gt40s.com/forum/gt40-build-logs/24525-toms-rcr-40-trackracer.html#post223405

THanks
TOM

 

[Bill Musarra]

I had to aproach my build a little differently than most. The spyder is set on the frame at the factory and all else is fitted from there. The spyder section involves welded panels and epoxyed fiberglass. So there isn't any adjustment in that area. The car was bought as a roller with a lot of work required as there were old worn out corvette parts on it. The trailing arms were soillid T bars with no adjustment mechanism. The suspension was not set until later on in the build as it spent several years on jack stands. When put on the ground I setup the suspension so it could be gotten around to the various shops it had to go. When I got close to the final stage I did what I could based on postings of others who had set up their suspensions with parralel bars and the like. It isn't meant to be exact but enough so I could get some test driving done.During that time the rear bars were replaced with rose joints and much beefier bars at or about the time I had the headers made and I am sure they were not set as the final setting and it just got overlooked. Before going out for the the test drives, I trued up the rear wheel settings to 0 toe and camber. I have an appointment with a qualified shop in the spring to do the corner weights and final setting of the suspension. I thought I had set the wheel positions some time ago, but with a long drawn out build, it just got missed.
When I was looking over the car after the first drives, it was then I noticed a rub on the rear of one of the wheel wells. That and this thread told me I needed to recheck them. The car is now garaged for the winter. It will have a through going over and some new additions will be done as well.

Bill

 

[Bill Musarra]

Tom,
I followed your link back to your build. Somehow I missed this early par of your build somehow. You lay things out very well. I will go back over my setup with modifications of your technique, since my spyder is fixed in place. I am sure I can get it better(the rear anyway). The front is C-4 corvette and will have to go to the shop for that one. Thanks

Bill

 

[rick]

Bill, 1.5 inch and you did not notice anything? wow I think I'll leave my 1/4 inch as is and go on with the build...

 

[Bill Musarra]

Rick,
Got to remember that the rear wheels were set to level and straight. So unless driving as in competition I don't think you could notice anything different in the ride. This was city driving with a little interstate at or slower than the traffic. There wasn't any binding of the axels or noise at any speed. At least none that I could detect. Go over Tom's link for setting the wheels and you will get them where they need to be. I am hampered by the fact that I have the Corvette front setup. So that is a shop item to setup. The rears are just measurements and adjustments(when you do it correctly). There I am hampered by the spyder being set and unmovable. That said I just have to alter the aproach. The results should be about the same.


Bill

 

[Vaughn]

Any suggestions for flexible cooling tubes to get air to the brakes?

 

[Fran Hall RCR]

Vaughn...unless you are braking repeatedly from very high to low speed there is no real requirement for cooling ducts/hose..

HRPWORLD.COM has a lot of ducts and hose available , should you need it

 

[Vaughn]

Nice to hear from you Fran-- Just finishing up the bodywork before we lay down the paint. Filling space to make everything clean and tidy.