Penske Shocks

Does any one have the model numbers and series of the shocks we are running on the WC cars? I can not find info.on the shock bodys. Thanks

Jim, I don't have a WC car but I do have Penskes. They are the single adjustable, coilover body 7500 series and I'm sure are the same thing that come on the GTS car. I got mine used / rebuilt from a local short track shop. I will measure them and let you know which ones I have.

Jim

http://www.penskeshocks.com/Sports_Car-Formula_Car-7500_Series.php

Jim;
How much of an improvement over the Konis are the Penskes? I've been debating this for a while, trying to rationalize the $3k. Common lore says that the Koni's are good for a few laps, but then they start to go away. Most of my races are sprint type last between 20 and 30 minutes, so I don't know if I need to worry.
If you don't mind telling the forum, what did you pay for your set?

Hi Jerry, I paid $1400 for a used set that were rebuilt. I wouldn't buy a new set. I'm very happy with them and the springs. Consistency is exactly what they did for the car. The car would go away during the session. It sort of felt like the tires were getting greasy. Now that's a non-issue and it's the same throughout.

The guy that did the work put 1 of our Konis on his shock dyno. As I recall he said they fell off 25% from what they should be in pretty short order. Once they got some heat in them they went away.

I would check around for circle track guys / shops. I think that shock is very common among that crowd and there is a shock guy that takes care of them somewhere nearby.

Jim

Jim;
How much of an improvement over the Konis are the Penskes? I've been debating this for a while, trying to rationalize the $3k. Common lore says that the Koni's are good for a few laps, but then they start to go away. Most of my races are sprint type last between 20 and 30 minutes, so I don't know if I need to worry.
If you don't mind telling the forum, what did you pay for your set?

I have asked my self the same question (Koni Vs Penske) and come to the following conclusions;

Shocks "going away over successive laps" is usually due to heat build up impacting dampening performance.

Both the Penske and Koni are alloy bodied and neither has a seperate oil reservoir. Both should therefore have similar heat dissipation capabilities.

Given this, it seems likely that the type of oil that is run in the shock is the most likely cause for deterioration of performance of the Koni.

I have had my Koni's serviced and the oil changed to a top quality synthetic shock oil. We have not experienced any issues with the "shocks going away" in either of the 6 hour races we have competed in (we cover approx 900kms over the 6 hours with average lap speeds up around 100mph).

While I cannot directly compare Penske Vs Koni lap time performance, given that they are both single adjustable shocks (Penske?) you have the same tuning options so should not be to much difference assuming that you do not have shock oil related fade issues.

Thoughts on this?

Kel.

Jim, I don't have a WC car but I do have Penskes. They are the single adjustable, coilover body 7500 series and I'm sure are the same thing that come on the GTS car. I got mine used / rebuilt from a local short track shop. I will measure them and let you know which ones I have.

Jim

http://www.penskeshocks.com/Sports_Car-Formula_Car-7500_Series.php


Thanks thats what I needed.We are looking at seperate nitrogen reserviors for the units. The rears are a pain to check.

I have asked my self the same question (Koni Vs Penske) and come to the following conclusions;

Shocks "going away over successive laps" is usually due to heat build up impacting dampening performance.

Both the Penske and Koni are alloy bodied and neither has a seperate oil reservoir. Both should therefore have similar heat dissipation capabilities.

Given this, it seems likely that the type of oil that is run in the shock is the most likely cause for deterioration of performance of the Koni.

I have had my Koni's serviced and the oil changed to a top quality synthetic shock oil. We have not experienced any issues with the "shocks going away" in either of the 6 hour races we have competed in (we cover approx 900kms over the 6 hours with average lap speeds up around 100mph).

While I cannot directly compare Penske Vs Koni lap time performance, given that they are both single adjustable shocks (Penske?) you have the same tuning options so should not be to much difference assuming that you do have shock oil related fade issues.

Kel.

I like the suggestion and general direction. I have a used set of Koni's. I think I'll get them rebuilt with higher temp rated syn oil. Any idea of the rating of the current oil? I'm sure Koni won't tell me. Maybe I'll go read the product info that came with the shocks.... What an idea.:loser:

I like the suggestion and general direction. I have a used set of Koni's. I think I'll get them rebuilt with higher temp rated syn oil. Any idea of the rating of the current oil? I'm sure Koni won't tell me. Maybe I'll go read the product info that came with the shocks.... What an idea.:loser:

Jerry, I took my shocks to my local Koni dealer and he suggested the oil upgrade. If you have a good dealer in your area that is what I would recommend.

The Koni's are also upgradable Jerry and can be converted into a 2 way adjustable shock as well for around $200 a peice. I have been told that the core shock unit is actually a very good unit and has been used on quite a few open wheel cars in various series over the years with great success.

For those that have the car feel greasy after a few laps, one thing to check is what your tire pressures are spiking to after 15 - 20 minutes of running. We had this happen in last years 6 hour at about the 4 hour mark. The car started oversteering in a 120mph sweeper. Happened to me about 10 laps in a row before I decided to trim back the pace a little. Turned out the LH rear tyre pressure had spiked up to 38 psi from our ideal hot running pressure of around 32 psi. We did not have this issue again this year due to different tyre pressure management. Another trick to prevent this is to run nitrogen in the tyres instead of air.

Kel.

Thanks Kel. I'll find the nearest Koni rebuilder to Albuquerque, and see about getting my spare set rebuilt with better spec syn oil and 2 way adjustable. Probably just one more way for me to screw up the cars handling. :iceslolan

What tires are you running? I've been slowly lowering my starting pressure in my Hoosiers for the past three races. The car is responding well to the lower pressures. I'm running them hot at about 36 psi. THat's where the Koni Cup guys say they are the fastest. I don't have the greasy feel as much. New scrubs are great at these temp as the car feels very neutral and turns in nice and sharp. As the tires have more temp cycles, and less rubber the car goes to a understeer condition, and I experience more rear wheel spin coming out of slow corners. Pretty predictable.

Thanks Kel. I'll find the nearest Koni rebuilder to Albuquerque, and see about getting my spare set rebuilt with better spec syn oil and 2 way adjustable. Probably just one more way for me to screw up the cars handling. :iceslolan

What tires are you running? I've been slowly lowering my starting pressure in my Hoosiers for the past three races. The car is responding well to the lower pressures. I'm running them hot at about 36 psi. THat's where the Koni Cup guys say they are the fastest. I don't have the greasy feel as much. New scrubs are great at these temp as the car feels very neutral and turns in nice and sharp. As the tires have more temp cycles, and less rubber the car goes to a understeer condition, and I experience more rear wheel spin coming out of slow corners. Pretty predictable.

Jerry, I am running 17" x 9" rims front and rear with Kumho Victoracer 255/40/17 fronts and 275/40/17 rears. We are getting great life from the Kumho's and they have proven to perform very consistenly over 6 hours if pressures are managed well.

We start with staggered pressures which are different front to rear and side to side which suits the track we are racing on the most. Cold pressures vary from 24 - 26 psi and we look for around 31 - 32 psi hot.

I have run Hoosiers in the past and was somewhat surprised by Hoosiers tyre pressure recommendations as these are a lot higher than we would normally run over here. I am sure they do a lot of testing in the States so know what works in their product over there.

Kel.

Thanks Kel. I'll find the nearest Koni rebuilder to Albuquerque, and see about getting my spare set rebuilt with better spec syn oil and 2 way adjustable. Probably just one more way for me to screw up the cars handling. :iceslolan

What tires are you running? I've been slowly lowering my starting pressure in my Hoosiers for the past three races. The car is responding well to the lower pressures. I'm running them hot at about 36 psi. THat's where the Koni Cup guys say they are the fastest. I don't have the greasy feel as much. New scrubs are great at these temp as the car feels very neutral and turns in nice and sharp. As the tires have more temp cycles, and less rubber the car goes to a understeer condition, and I experience more rear wheel spin coming out of slow corners. Pretty predictable.
one of my Koni shocks is leaking.. so living near Amarillo..what was the best and closest rebuilder..for Konis.. thanks Bill

I didn't find a local Koni rep that could rebuild the shocks. My suggestion is to try:


Pro Parts West
21417 Ingomar St. Unit #7
Canoga Park, CA 91304
(818)888-8904

Givre them a call and see what they charge for a rebuild. Let me know what they charge for a set of 4 shocks.

Jerry, thanks...talked to them, not a exact replacement available..
old # 30-1695(built for panoz)--new # 30-6436 --front $148.00 (less springs & adjusters)
old #30-1696( '' '' )--new # 30-7325 -- rear $148.00
went with old stock new from Joe ( 423-314-5041) who bought all of Gary Jones & Wire Wheel stock of parts . When the recession is over would like a good adjustable shock. thanks Bill

Jerry, thanks...talked to them, not a exact replacement available..
old # 30-1695(built for panoz)--new # 30-6436 --front $148.00 (less springs & adjusters)
old #30-1696( '' '' )--new # 30-7325 -- rear $148.00
went with old stock new from Joe ( 423-314-5041) who bought all of Gary Jones & Wire Wheel stock of parts . When the recession is over would like a good adjustable shock. thanks Bill

Have you got the steel yellow bodied Koni's or the black alloy bodied ones?

Reason I ask is that I have the black alloy bodied units (single adjustable) and these are definitely serviceable/rebuildable. They can also be modded to be 2 way adjustable at moderate cost. Just had mine serviced (dynoed, oil changed, recharged, re-dynoed) at our local Koni agent here in NZ.

Kel.

Kel, Wish they were the black rebuildable---yellow crimped together cheap ones. thanks Bill