GT - Shorten lower front bump stops?

acalvi · #1 (**permalink**) 10-15-2009, 08:31 AM

In some pictures showing the front suspension of lowered GTs (for example @ Alfaholics), I saw shorter lower bump stops, about half the height of original.

I'm rebuilding my suspension (GT Junior 1300 stepnose) and have Alfaholics spring kit B, shall I cut mine?
Or shall I check travel / clearance without spring before?
Any advantages?
Sumpguard needed?

gattia86 · #2 (**permalink**) 10-19-2009, 10:48 PM

On all US-spec GTVs I've seen, there is a 1/4" steel spacer sandwiched between the front bumpstops and the chassis. I'm guessing these were installed for the taller US ride height. They're real easy to remove, and I would deffinately do so if lowering the car from stock US-spec height.

The rear of the car has a similar aluminum spacer sandwiched under the bumpstop, and I'd remove it, too, to gain a bit more suspension travel if you're lowering the car.

I haven't seen any shorter bumpstops offered, although this seems like a good idea, since when lowered, the car sits only an inch or so off the nose of the bumpstops.

Don't simply cut the stock ones shorter... it'll remove most of their progressive nature, and the ride will become much harsher over big bumps.

I've actually modified my stock front bumpstops by cutting them shorter, then cutting a new tapered shape and drilling out the center to restore the progressive spring rate of the bumpstop... but I haven't seen anyone else go to this length, and can't say that I feel any difference while driving. In the rear, I've replaced the stock bumpstops with ones from a Mercedes W114, which are softer and more progressive... and these work better than the stock ones with my very low rear ride height.

George

'74 GTV 2000

**davbert** · #3 (**permalink**) 10-21-2009, 12:14 AM

alcavi

if your refering to the alfaholics pic with the geomtry fix kit which moves the spindle up. that kit moves the hub up 2-2 1/2 inches i reckon so the bumpstops need to be trimmed.

if your running shorten 1200lbs up front i dont thinks its a problem but i think max's stuff has much lower rates.

let us know if he recommends trimming them or not.

db

george

how often doe your bumpstops come in contact with the suspension?

gattia86 · #4 (**permalink**) 10-21-2009, 06:08 AM

Quote:

Originally Posted by davbert

george

how often doe your bumpstops come in contact with the suspension?

**davbert** · #5 (**permalink**) 10-21-2009, 10:45 AM

something is seriously not correct if your bottoming out while driving.

in the front, bumpstop should only be in effect on extreme wheel travel situations to avoid damaging the suspension i.e. huge pot holes, inadvertent jumps, etc...

if your ride quality is affected by your bumpstops most likely your car's handling may snap spin in hard cornering which is a dangerous situation. your suspension should not come in contact with the bumpstops even in hard track driving.

my 2 cents

**101 Alfa Mike** · #6 (**permalink**) 10-21-2009, 03:52 PM

The books suggest putting tie wraps around the shock/strut shafts to see just how much suspenion travel you are using. It is good advice. I did it on my non-Alfa car and discovered that a leasurely tour around the block was enough to bottom the suspension at all 4 corners!

**davbert** · #7 (**permalink**) 10-21-2009, 03:56 PM

or you can use clay for a quick an dirty way to find out...

your wont have to take your springs out to check the travel.

gattia86 · #8 (**permalink**) 10-21-2009, 11:55 PM

Yes...yes... I know what you're saying, but take a look under a lowered 105/115 Alfa (when it's sitting on the ground) some time. There's simply not much suspension travel before the car contacts the bump stops.

This in itself is not a big deal, and is NOT the same thing as "bottoming the suspension", which, yes, is the end of suspension travel and can lead to a spin.

That's why the bump stops are progressive... to slow the suspension movement BEFORE it reaches the end of its travel. It's just another spring, really, with a given rate per inch of deflection.

Many OEM cars run at or near their bump stops by design.

Yes, I've checked shock travel, and the rear uses about 2" of travel fully burried in the bump stops (about 3" total bump travel from static ride height).

At any rate, I can't feel any difference with the shorter stops in the front, but can feel a dramatic difference by fiddling with the bump stops in the rear.

George

**smestas** · #9 (**permalink**) 10-22-2009, 02:27 AM

I'm no expert but I'd think if you are hitting your bump stops on a regular basis you need stiffer springs. My 2 cents.

Bjornbusen · #10 (**permalink**) 11-05-2009, 03:17 PM

Strange, this is a weird thread, are you seriously using rubber bumpstops as part of the springs on a lowered car? seriously? If you hit the bump stops, just remove them, if you after that still hit something, switch to springs that fit your car.

Bump stops are not part of the cars setup. If anything they are servicing aids.

Progressive bumpstops? Come on guys...

**101 Alfa Mike** · #11 (**permalink**) 11-05-2009, 04:06 PM

They are progressive -- as opposed to linear or digressive.

**davbert** · #12 (**permalink**) 11-05-2009, 07:21 PM

whether they are progressive or not they shouldnt come into play when driving you car. thats why they are called a bumpstop. they are there to prevent damage once the suspension is overextended during compression or rebound