IRS bushing replacement

ive searched on thesamba and can not get a definitive answer. in order to try and eliminate wheel hop im going to install saco bushings and rhino tran and engine mounts. i have a '69 rear end. trying to figure out the innner diamter of the bushings that i need. apparently they are sold in 2 sizes, 1-3/4" and 1-7/8". i have a set of new rubber bushings in front of me. the outer (round) measure 1.75". easy enough. the inner (knobby) bushings are coming in at 1.83". bigger than 1-3/4", smaller than 1-7/8". does it make sense that the inner diameter would be different? i could be splitting hairs.

paul

isnt wheel hop from the frame horns flexing under load?

i put in a kafer bar and my wheel hop was greatly reduced.

A 69 IRS should be using a 1 7/8" ID knobby on the inside and a 1 7/8" ID round on the outside. (Assuming you have stock spring plates.)

The rubber bushing sounds right for a 1 7/8". Rubber bushings are not usually designed so the parts can rotate in them. They are designed to solidly grip both pieces so it's the rubber itself that twists and distorts as the parts are rotated. Urethane is hard enough that it can withstand having parts rotate against it without wearing out.

Wheel hop is often from frame horn flexing or worn trans mounts.

Wheel hop is a combination of things. Frame horn flex, torsion / spring plate bushings being worn or weak, and if it is an IRS car the pivot bushings.

Tighten all these up and have a car that launches sweet and handles even better!!!

Yes, what Kevin said. Think about the soft rubber engine mounts. You get on it hard and the engine pushes down compressing the rubber as it rebounds it has more momentum to bring the frame horns up. That isn't the exact science but it's how I make sense of it. The rubber allows certain movement of all pieces. Also provides for a Cush ride. Slight Movement of your bushings at the spring plate are exaggerated by the time it gets to the wheel.

Kevin, don't think I can afford to brace the frame horns at this point... I'm freshening up the top end of my motor. I understand your brace can not be used with heater boxes, correct? If that's the case and you wouldn't mind could you suggest a brace that does work? I already contact the place in Canada, the name escapes me, but they don't fabricated the part anymore.

here is a pretty good link over on The Samba that discusses this. thought I would post it for future generations of speedster owners quick reference.

http://www.thesamba.com/vw/forum/viewtopic.php?t=495408&highlight=wheel+hop

That is correct, ours can not currently be used with heater boxes. We investigating a way to make a 6 point that can be used with heater boxes. until then I think the eyeball one can be used with heater boxes???

My Fast Fab kafer bar does work with my heater boxes.

But, I had to cut a little off the lever the cable attaches to on the driver side and bend the post it pivots on a bit.

The Fast Fab bar is 1" tubing. Some others are 3/4".

ive been waiting for a breather from fast fab for over 14 days since they received payment. they have not returned my phone calls concerning the order. they will not be receiving anymore of my hard earned money. there are options out there... too bad businesses forget that. but thank you for the heads up.

I am very surprised. Robert there was very responsive when I had questions.