Suspension travel

[jesseandersson]

I have a -71 911T with 2.7 p/c Weber IDS etc. built to a street beater in the late 80s with RS flares, 26mm rear TBs, new (standard, red 69-71) konis on all corners with 195/65/15 // 215/60/15 tires.

The car is low and I would probably need raised spindles in front to get the correct rake with current rear ride height. Also my current rear shock travel is very, very limited and it doesnt feel good..

I would like to be able to drive on somewhat uneven roads without loosing my kidneys and swallowing my fillings.. I know its a trade off but what is the somewhat shared consensus on my current setup? Will I have to buy shorter rear shocks?(Bilsteins sports) or am I OK if I raise the rear 3/4 inch...?

Grateful for input and/or discussion!





Jesse

[Jerry L]

I would not think your rough ride is due to shock travel unless they are stuffed full of buffers, the easy thing to do is measure the rear shock as mounted (fully weighted) then pull shocks and check extension & compression lengths and what buffers may be in the assembly. Check fronts as well. Yes the raised spindle will drop the nose but I think you have to figure out where your suspension is at before you start with more changes, 26 rears is not wild, what do you have on front? you say new Koni's why not figure out what is making the rough ride before jumping into different shocks? Have you used the front T bar adjustment bolts to see if you can drop the front a bit "if" that is the intention?

Regards

[RSTarga]

You need to raise the front too, you are riding on your shock buffers

[jesseandersson]

Sorry for being unclear!

The front feels OK, buffers cut off and no clonking or bottoming out so far.

I only have about 2" travel in the rear and thats almost the height of the buffers which I removed for the test ride. I'd like to run the rubbers as intended but the geometry doesnt seem to add up.

How much travel is needed for spirited driving( not rallying)?

I know this is a tricky request but please ellaborate if you have any experience!

Regards

[edmayo]

I'm not sure why you think you want the front so raked down, but here is how I determined suspension travel for autocross usage. You have to remove the dust collars, but to do that you must run a washer of the same I.D. as the collar on top of the shock or you will just drive it out the top mount. ( or just knock the ends out of some old collars) Now you can put a ty-wrap around the shock piston and drive around (without bumpstops) and see how far you have moved the ty-wrap. That's how much travel you need.

[jesseandersson]

My english is a bit rusty so please excuse me!

Im not looking to lower the front end but only concerned about the shock travel in the rear, if I decide to raise the rear I will (of course) follow up with the front.

Thank you for your input Ed! Thats how we set up travel on our motocross bikes so I'm familiar with the process

[keith]

sounds like you are bottoming the shocks to me. you've already said it; drop the front spindles to increase your usable stroke up front, shorter bodied shocks in the rear if you want to keep the ride height (which looks tasty from here.)

[chris_seven]

With a 26mm rear bar you need around 15mm of travel on the rear before the car touches the bump stop and then you still need further travel to allow the bump stop to deform progressively.

If you have a lowered rear ride height we normally fit a 38mm long progressive bump stop designed for the job along with a standard length damper.

Using a shorter damper would need a different arrangement of bump stops and is not something we have experience with.

If you shorten the standard bump stop the transition from not touching to using the bump stop will be quite abrupt and will seem 'crashy' when compared to a normal bump stop at standard ride height.

This is because the bump stop will effectively be stiffer and the progression curve will be less than ideal.

We generally set the cars we build about 1.5 degrees nose down.

We also modify the front bump stops on lowered cars and normally we don't move the spindles as RSR ride heights are generally too low for UK roads with all the 'blank-blank' speed humps.

[jesseandersson]

Very greatful for your help guys!

Will test the rear travel, adjust accordingly and give it a try!

Regards