first gen suspension stuff

[benracin]

My racing car is an '83 and been doing the racing gig for probably the last 8-10 years on and off. The car was new to me a couple years ago and now that the gift buying season is over I'm looking at throwing money at the car again. I know it's been a long time since the suspension had anything done to it so I'm thinking about replacing/upgrading all the little stuff that cars tend to need over time. Stuff like bushings, rubber bits, bearings, blah blah blah.

Towards the end of last year the car would get a loud rumble at high speeds that would be there some laps and gone the next. Looking around at websites I'm kind of thinking that maybe something in the rear end is binding and staying that way. The car has the Watts link set up.

So knowing that the car is old and can use a good tuning up, is there anything out there that you experienced folk know the car needs or anything you would recommend. I'd love to replace everything but I've got to save some money for shocks!

Thanks again and happy new year!

[Boswoj]

I assume that you are keeping up on the regular maintenence items? Sometimes that rumbling from the rear is axle bearings going away!

Boswoj

[benracin]

Axle bearings you say? That would be interesting. Would that cause a rumble that would be there some laps and not some others? It also seemed to me that when this rumbling was taking place I wouldn't have the same speed as normal. Once it was rumbling bad and I got easily passed by an ITB car on the straight only to get him back a bit later.

Thanks.

[benracin]

sorry, double post.


[This message has been edited by benracin (edited January 08, 2004).]

[Speed Raycer]

I've got the same thing, rumble/groan that happens after a long straight into a turn. Most say its either a rear bearing or rod ends.

The funny groove on my rear drivers disk leads me to believe that it might be a bearing.

------------------
Scott
It's not what you build...
it's how you build it
http://www.angelfire.com/mo3/rudder_racing/images/RX7_Pictures/SRsRX/sig58.jpg (http://www.izzyscustomcages.com) http://www.angelfire.com/mo3/rudder_racing/images/IzzysImgs/IzzysLogoDSsmall.jpg (http://www/izzyscustomcages.com)

[ddewhurst]

***I got easily passed by an ITB car on the straight only to get him back a bit later.***

he he he, ya better get that fixed or the Spec-7 will get ya next year. http://Forums.ImprovedTouring.com/it/smile.gif http://Forums.ImprovedTouring.com/it/smile.gif http://Forums.ImprovedTouring.com/it/smile.gif

Have Fun http://Forums.ImprovedTouring.com/it/wink.gif
David

[Tak]

Rumble on the straight...getting passed by ITB. Could also be engine knock or loose driveshaft u-joint. If you can rattle the U-joints, they need replacement. Always use a genuine Mazda U-joint. All the aftermarket ones seem slightly undersized. I also recommend balancing drive shafts.
Seriously, engine knock at high speed feels and sounds like a bad chassis vibration.

Tak

[Eagle7]

Originally posted by Tak:
...I also recommend balancing drive shafts...
Tak
(Trying without success to conceal my ignorance) How do you do that?

------------------
Marty Doane
ITS RX7 #13
CenDiv WMR

[bcarter]

Didn't I read here somewhere that the diff, if not tight, can also make a pounding noise in corners?

[Boswoj]

Well - I went so long before replacing my axle bearings that the endplay allowed the rear disk to touch the pads in high speed corners - slowing me down considerably! I like to think I am learning proper maintenece one mistake at a time......

[benracin]

Well now that brings up a big one. The first time I noticed this rumble was the carousel at Road America. Through that long high speed right hander a really bad noise/rattle started to develop and every now and then you would hear a popping like things were flying off the car. Wondering if I still had rear wheels made 'the kink' all that much more fun. But what you've described Boswoj sounds a lot like that. Could that show up on straights though?

And David, rumor has it that you'll be an IT7 car next year? If that's true I'll have to do more then just mess with your brakes to keep you away from me I guess. http://Forums.ImprovedTouring.com/it/smile.gif

Ben.

[jake7140]

Don't worry Ben, I'll be with ya in spec next year (hopefully watchin' you in my rear-view!) assuming new tranny and clutch get in, and some other bugs worked out.

I always make the mid-August RA event at least.

------------------
Steve
[email protected]
<A HREF="http://www.geocities.com/jake7140" TARGET=_blank>My racing page
</A><A HREF="http://www.geocities.com/elrss" TARGET=_blank>Elkhart Lake Racing_&_Sipping Society
</A>

[Tak]

Eagle-
I balance my driveshafts by taking them to a drive shaft shop that has a balancer. It should run about $60. At the shop they spin it, then weld weights on to balance it. They should only need balancing after replacing u-joints.

Ben-
If your vibration is happening on the straights, it is most likely not bearings.
Wheel bearings tend to make noise when unloaded. Ie, if there is bearing noise in a right hand turn, inspect the right side (unloaded) bearings. Differential bearings will whine, with the tone increasing with wheel speed. Additionally, if the diff is making noise, the noise will change with throttle on and throttle off.
If I run too much spark advance, I hear knock around 6500rpm in 4th gear only--I think engine speed changes too fast in lower gears (and I don't use 5th).

Originally posted by bcarter:
Didn't I read here somewhere that the diff, if not tight, can also make a pounding noise in corners?

oh yea, what hes descibing is what happened to me at laguna last year, third member was falling out, mostly shook the car and pounded at the end of the staights though, sometimes in corners right before a shift.



[This message has been edited by 7'sRracing (edited January 10, 2004).]

[benracin]

Thanks for the awesome advice gents. And sorry Steve, I'm one of those IT7's as well. http://Forums.ImprovedTouring.com/it/smile.gif I ran ITA by mistake this last year. Although I wasn't very competitive I managed 2nd in the championship! I won't tell you how many people were in that championship. Takes all the joy out of it. Lets just say I didn't have to beat many people. I'll just go hug my trophy.

3 cheers for strange rumbles!